JP2013033251A - Television receiving device and surface light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a television receiving device in which a surface light source device having almost no luminance unevenness (hot spot) in the vicinity of a light incidence surface of a light guide plate while using a plurality of point light sources is used as a liquid crystal display device.SOLUTION: A television receiving device comprises: a surface light source device including a light guide plate having a light emission surface, a counter surface facing the light emission surface, and at least one light incidence surface held between the light emission surface and the counter surface, and a plurality of point light sources disposed in the vicinity of the at least one light incidence surface of the light guide plate; a display panel disposed to face the light emission surface of the light guide plate and having a display area allowing display by adjusting light transmission and having a light-blocking frame defining the display area; and a tuner receiving a broadcasting video signal. The at least one light incidence surface of the light guide plate has a plurality of openings or concave parts or convex parts whose bottom planes have an anisotropic shape which is long in a direction perpendicular to the light emission plane.

Description

  The present invention relates to a so-called edge light type surface light source device, for example, a surface light source device suitable for use in a liquid crystal display device, and a television receiver using the surface light source device.

  In the liquid crystal display device, an edge light type surface light source device is often used. Such an edge light type surface light source device generally includes a light guide plate that emits light from the light source to the liquid crystal display panel side, and an LED (light emitting diode) or CCFL (cold cathode) disposed on the side of the light guide plate. Light source such as a tube) and a prism sheet (having a prism structure having a ridge line parallel to the light incident surface of the light guide plate on the surface) for directing light emitted from the light guide plate toward the liquid crystal display panel. The The light guide plate generally has a light exit surface, a facing surface facing the light exit surface, and at least one light incident surface sandwiched between the light exit surface and the facing surface, and is incident from a side portion (light entrance surface). The light to be reflected is repeatedly reflected inside the plate and guided, and the guided light is emitted from the light exit surface to the liquid crystal display panel side by a light emitting mechanism provided on the opposing surface.

  By the way, when such a light guide plate is used in combination with a plurality of point light sources, a uniform luminance can be obtained in the central region of the light exit surface (region away from each point light source to some extent), but it is close to the point light source. In the area near the light entrance surface, the partial area directly facing the portion between the point light source and the point light source is dark, but an extremely bright so-called hot spot appears in the partial area directly facing the point light source, resulting in uneven brightness. There is a disadvantage that it ends up.

  Therefore, in the surface light source device using a plurality of point light sources as the light source, there is a problem that substantially only the center portion of the light exit surface of the light guide plate can be used.

  As a light guide plate for preventing such luminance unevenness, Patent Document 1 provides a plurality of grooves that intersect with each other in an oblique direction with respect to the traveling direction of the light beam of incident light on the facing surface that faces the light exit surface. A light guide plate is disclosed.

  Patent Document 2 discloses a light guide plate having a trapezoidal concavo-convex structure in which a symmetrical triangular shape is formed on a light incident surface, and Patent Document 3 includes an opening on a light incident surface. Light guide plates each having a substantially quadrangular shape and a recess having an arcuate corner at the bottom are disclosed.

  Further, Patent Document 4 discloses a light guide plate that is knurled on the opposite surface and periodically finely cut such as a lenticular shape on the light incident surface. Patent Document 5 discloses a light guide plate on the light incident surface. A light guide plate provided with an anisotropic light diffusing adhesive layer comprising an adhesive and a needle-like filler is disclosed.

JP 2003-107247 A JP 2002-169034 A JP 2003-215346 A JP 2006-49286 A JP 2008-34234 A

  However, in the light guide plates disclosed in Patent Documents 1 to 5, improvement in luminance unevenness when used in combination with a plurality of point light sources is not sufficient, and hot spots near the light incident surface cannot be erased.

  Furthermore, the techniques disclosed in Patent Documents 2 and 3 are complicated in the structure of irregularities and depressions formed on the light incident surface, and thus are compatible with small LEDs having a light emitting surface width of 5 mm or less that have been used in recent years. It is difficult to provide a sufficient number of irregularities and depressions on the light emitting surface. Moreover, since the technique disclosed in Patent Document 4 needs to perform a rotlet cut on the opposite surface of the light guide plate, it is difficult to apply to a light guide plate used in a large-sized liquid crystal television, and costs increase. . Moreover, since the anisotropic light-diffusion adhesive layer in the technique currently disclosed by patent document 5 has the structure by which the acicular filler is disperse | distributed in an adhesive, the precision of anisotropy is low and it is immediately after light-guide plate light incidence. Light leakage is so severe that a quality sufficient for use in a display device cannot be obtained.

  The present invention has been made in view of the above points, and while using a plurality of point light sources, there is almost no occurrence of luminance unevenness (hot spots) in the vicinity of the light incident surface of the light guide plate. It is an object of the present invention to provide a surface light source device having a uniform luminance distribution over almost the entire light output surface and a television receiver using the surface light source device as a liquid crystal display device.

As a result of intensive studies on the light guide plate, the present inventors have provided a plurality of concave portions or convex portions having long anisotropic shapes in the direction perpendicular to the light exit surface on the light incident surface. It has been found that luminance unevenness derived from a point light source can be reduced.
In addition to this, in the area near the light entrance surface of the light guide plate and / or the light entrance surface thereof, the portion where the light scattering degree of the partial region directly facing the point light source faces the portion between the point light source and the point light source When light scattering processing is performed so that the light scattering degree of the region is lower, the effect of the plurality of concave portions or convex portions provided on the light incident surface and the effect of the light scattering processing are combined to produce a hot spot or other It was found that the luminance unevenness derived from the plurality of types of point light sources can be eliminated, and a uniform luminance distribution can be obtained over the entire light exit surface.

  Furthermore, a surface light source device or a display device can be obtained by subjecting a specific region or a partial region to light scattering processing for a region other than the light exit surface of the light guide plate and / or a region near the light incident surface of the light guide plate. It has also been found that not only unevenness visually recognized from the front of (light-emitting surface) but also occurrence of unevenness visually recognized from an oblique direction can be suppressed.

  If the light guide plate of the present invention is used, even when a plurality of point light sources are used as the light source, it is possible to provide a surface light source device and a display device with almost no luminance unevenness.

It is the schematic of an example of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a surface profile figure which shows an example of the some recessed part or convex part (groove structure) formed in the light-incidence surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a surface profile figure which shows an example of the some recessed part or convex part (groove structure) formed in the light-incidence surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is explanatory drawing of the specific example of the manufacturing method of an uneven structure. It is sectional drawing of the multilayer film for light-guide plate manufacture in which the uneven structure was formed. It is the schematic of the sealing sheet of the multilayer film (sealing) for light-guide plate manufacture in which the uneven structure was formed. It is explanatory drawing of the specific example of the manufacturing method of the multilayer film (tape) for light-guide plate manufacture in which the uneven structure was formed. Explanatory drawing of a diffusion angle. It is the front schematic of the surface light source device of this invention. It is the schematic of the point light source (LED) which can be utilized for the surface light source device / TV receiver of this invention. It is the front schematic diagram of the liquid crystal display panel using the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows an example of a structure of the television receiver of this invention. It is explanatory drawing of the pitch and the depth of the recessed part which the light-guide plate contained in the surface light source device / TV receiver of this invention has in a light-incidence surface. It is a microscope picture which shows an example of the recessed part formed in the light-incidence surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. Transmission of light incident from the normal direction to a multilayer film (seal) for manufacturing a light guide plate having a plurality of recesses or projections in a direction perpendicular to the major axis of the opening (bottom surface) of the recess (projection) It is an angle distribution map of light intensity. It is a microscope picture of the specific example of a moth eye structure. It is a microscope picture of the specific example of several recessed part which has a moth eye structure on the surface. It is a conceptual diagram which shows an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows the luminance distribution of manufacture example A1-4. It is a graph which shows the standard deviation of the brightness | luminance in the light emission surface of manufacture example A1-4. It is sectional drawing of the preferable example of a liquid crystal display device provided with the surface light source device of this invention. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a photograph of the specific example of the reel which can be used for manufacture of the film (tape) for light-guide plate manufacture which formed the several recessed part or convex part. It is explanatory drawing of a dot density. It is sectional drawing of an example of a liquid crystal display device provided with the surface light source device of this invention. It is the elements on larger scale which show the example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show the specific example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows the light-scattering process given to the opposing surface of the light-guide plate of the surface light source device of manufacture example A-5. It is a figure which shows the brightness nonuniformity (SD value) of the surface light source device of manufacture example A-5, and P / G. It is a figure which shows the light-scattering process given to the opposing surface of the light-guide plate of the surface light source device of manufacture example A-6. It is a figure which shows the light-scattering process given to the opposing surface of the light-guide plate of the surface light source device of manufacture example A-11. It is a figure which shows the relationship of the brightness nonuniformity (SD value) of manufacture example A-11, and P / G. It is a figure which shows the brightness nonuniformity (SD value) of manufacture example A-13, and the relationship of P / G. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows arrangement | positioning of the reflective sheet bonded by the side surface of the light-guide plate in manufacture example A-14-15. It is a figure which shows arrangement | positioning of the reflective sheet bonded by the side surface of the light-guide plate in manufacture example A-14-15. It is a figure which shows arrangement | positioning of the reflective sheet bonded by the side surface of the light-guide plate in manufacture example A-14-15. (A), (b) The schematic sectional drawing of the principal part of a light source unit for demonstrating the relationship between the distance of a light source and an optical sheet, the distance between light sources, and brightness | luminance unevenness is shown. (A) The projection area | region of the line light source which comprises a light source unit, and the projection area | region between line light sources are shown. (B) The projection area of the point light source which comprises a light source unit, and the projection area between point light sources are shown. (A) Explanatory drawing of a diffusion angle is shown. (B) A schematic diagram of transmitted light intensity when light enters from the normal direction of the diffusion sheet is shown. The distribution (for 1 period) of the diffusion angle with respect to the relative position in the diffusion sheet surface is shown. (A)-(f) The distribution with respect to the relative position in a surface of the diffusion angle of the diffusion sheet of specification 1st invention is shown. An example of arrangement | positioning of the high diffusion angle area | region and low diffusion angle area | region of the diffusion sheet of specification 1st invention is shown. An example of arrangement | positioning of the high diffusion angle area | region and low diffusion angle area | region of the diffusion sheet of specification 1st invention is shown. An example of arrangement | positioning of the high diffusion angle area | region and low diffusion angle area | region of the diffusion sheet of specification 1st invention is shown. (A) The schematic perspective view of an example of the light source unit of specification 1st invention is shown. (B) A schematic perspective view of another example of the light source unit of the first invention of the specification is shown. (A) The schematic perspective view of an example of the light source unit of specification 1st invention is shown. (B) A schematic perspective view of another example of the light source unit of the first invention of the specification is shown. (A) Explanatory drawing of a diffusion angle period and a light source space | interval in an example of the light source unit of specification 1st invention is shown. (B) Explanatory drawing of a diffusion angle period and light source space | interval in another example of the light source unit of 1st specification of this invention is shown. Explanatory drawing of an example of the relative positional relationship of the diffusion angle distribution of the diffusion sheet of specification 1st invention and a light source is shown. (A)-(c) The schematic perspective view of the specific structure of the light source unit of specification 1st invention is shown. (A), (b) The schematic perspective view of the specific structure of the light source unit of specification 1st invention is shown. (A)-(d) The schematic perspective view of the specific structure of the light source unit of specification 1st invention is shown. (A), (b) The schematic perspective view of the specific structure of the light source unit of specification 1st invention is shown. The arrangement pattern figure of the LED light source in manufacture example B is shown. (A) Explanatory drawing of the relative positional relationship of a diffusion angle distribution and a light source in the diffusion sheet of manufacture example B-7 is shown. (B) Explanatory drawing of the relative positional relationship of a diffusion angle distribution and a light source in the diffusion sheet of manufacture example B-8 is shown. It is the front schematic of the liquid crystal display panel using the light-guide plate contained in the surface light source device of this invention. It is a conceptual diagram which shows an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a conceptual diagram which shows an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows the luminance distribution of manufacture example C-1 to 3 and 11. It is a graph which shows the standard deviation of the brightness | luminance in the light emission surface of manufacture examples C-1 to 3 and 11. It is a graph which shows the relationship between light scattering processing, the overlap of a flame | frame, and in-plane brightness | luminance. It is the figure which plotted the result (relationship of P / G and ρ2 / ρ1) of the reference experiment C2. It is the schematic of an example (ceiling lighting apparatus) of an illuminating device. It is a front view of an example (evacuation guide light) of an illuminating device. It is a figure which shows the luminance distribution of manufacture example C-21 and 31-33. It is a figure which shows the relationship between the distance from the light-incidence surface of the light-emitting plate of manufacture example D and a reference, and a brightness | luminance. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the relationship between the luminance unevenness of the manufacture example D and a reference, and the direction of a vertical groove. It is a graph which shows the brightness nonuniformity at the time of providing a groove structure in the light-incident surface with a gap. It is a graph which shows the brightness nonuniformity at the time of providing a groove structure in the light-incident surface with a gap. Luminance unevenness of Production Examples D-16 and 17 (surface light source device using a light guide plate having a vertically long recess) and Production Examples D-35 and 36 (surface light source devices using a light guide plate having a lateral groove recess) are shown. It is a graph. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a figure which shows the relationship between the diffusion angle of a light-incidence surface, and luminance unevenness. It is a surface profile figure which shows an example of several recessed part or convex part (groove structure) formed in the light-incidence part of a light guide member. It is a surface profile figure which shows an example of several recessed part or convex part (groove structure) formed in the light-incidence part of a light guide member. It is a surface profile figure which shows an example of several recessed part or convex part (groove structure) formed in the light-incidence part of a light guide member. It is sectional drawing of an example of a light guide member. It is a brightness | luminance profile of the light emission surface of the light-guide plate of the surface light source device of manufacture example E-1A. It is a brightness | luminance profile of the light emission surface of the light-guide plate of the surface light source device of manufacture example E-1B. It is a graph showing the relationship between G 'and G _0'. It is the elements on larger scale which show the specific example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show the specific example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows the light-scattering process given to the opposing surface of the light-guide plate of the surface light source device of manufacture example F-11. It is a figure which shows the relationship of the brightness nonuniformity (SD value) of the surface light source device of manufacture example F-11, and P / G. It is a figure which shows the light-scattering process given to the opposing surface of the light-guide plate of the surface light source device of manufacture example F-12. It is explanatory drawing of an example of the light emission pattern curve to the 1st direction of the whole light-incidence surface of the light-guide plate of specification 2nd invention. It is an isometric view schematic diagram of an example of the light-guide plate of specification 2nd invention. In the light guide plate of the specification second invention, an example of a plurality of recesses (grooves) formed in regions (first partial region and second partial region) having anisotropic light diffusion characteristics of the light incident surface It is a top view. In the light guide plate according to the second aspect of the present invention, the plurality of recesses (grooves) formed in the regions (first partial region and second partial region) having anisotropic light diffusion characteristics on the light incident surface It is a top view of an example. (A)-(f) It is a schematic diagram which shows the example of the partial area | region formed in the light-incidence surface of the light-guide plate of specification 2nd invention. It is explanatory drawing of the determination method of angle distribution (diffusion angle) of the emitted light intensity of a partial area | region when the size of a partial area | region is small with respect to the laser diameter of the laser light source used for a measurement. It is angle distribution of the emitted light intensity to the 1st direction of the 1st partial region alone. It is a figure which shows an example of the bright line which generate | occur | produces in a light emission surface when a diffusion structure is formed in the light-incidence surface of a light-guide plate. It is a schematic diagram which shows an example of the lenticular lens shape which can be formed in the 1st surface and / or 2nd surface of the light-guide plate of specification 2nd invention. It is sectional drawing which shows the lenticular lens shape which can be formed in the 1st surface and / or 2nd surface of the light-guide plate of the manufacture example G. It is a perspective view which shows the random several groove | channel which can be formed in the 1st surface and / or 2nd surface of the light-guide plate of specification 2nd invention. (A) (b) (c) It is the light emission pattern curve to the 1st direction of the whole light-incidence surface of the light-guide plate of the manufacture example G. (D) (e) It is the light emission pattern curve to the 1st direction of the whole light-incidence surface of the light-guide plate of the manufacture example G. FIG. It is the surface shape of the light-diffusion sheet 3 used for manufacture example G. It is the surface shape of the light-diffusion sheet A used for manufacture example G. 6 is a diagram showing an evaluation direction of Production Example G. FIG. It is an overhead view of an example of the line-shaped illumination system which comprises the diffusion sheet which concerns on 1st Embodiment of specification 3rd invention. It is a figure which shows the relationship between the direction where the diffusion angle of the emitted light of the diffusion sheet which concerns on 2nd Embodiment of specification 3rd invention shows the minimum value, and a streak pattern. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-4. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-4. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-4. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-4. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-4. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-14. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-14. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-14. It is a perspective view which shows the one aspect | mode of the state which affixed the tape-shaped member on the end surface of the plate-shaped member which concerns on embodiment of specification 4th invention. It is a perspective view which shows the one aspect | mode of the state which affixed the tape-shaped member on the one end surface of the plate-shaped member stacked in multiple steps concerning embodiment of specification 4th invention. It is a perspective view which shows the one aspect | mode of the state which protruded to the end surface of the board which concerns on embodiment of specification 4th invention, and stuck the tape-shaped member. (A) It is a model side view which shows the method of bonding a tape-shaped member to the end surface of a plate-shaped member using the reel by which the tape-shaped member which concerns on embodiment of specification 4th invention was wound. (B) It is a model top view of the bonding part of (a). (A) It is a conceptual diagram which shows the method of bonding a tape-shaped member to the one end surface of a plate-shaped member using the bonding jig | tool which concerns on embodiment of specification 4th invention. (B) And (c) It is a schematic cross section which shows the deformation | transformation of the contact part of the bonding jig | tool at the time of bonding. (A) (b) (c) Description It is a schematic cross section which shows an example of the contact part of the bonding jig | tool which concerns on embodiment of 4th invention. (A) It is a perspective view of the bonding jig which concerns on manufacture example I-1 and 2. FIG. (B) It is sectional drawing of the bonding jig which concerns on Example 1 and 2. FIG. (A) It is a perspective view of the bonding jig | tool wrapped in the plastic bag which concerns on manufacture example I-1. (B) It is sectional drawing of the bonding jig | tool wrapped in the plastic bag which concerns on manufacture example I-1. (A) It is a perspective view of the bonding jig | tool provided with the slipperiness concerning the manufacture example I-2. (B) It is sectional drawing of the bonding jig | tool provided with the slipperiness concerning the manufacture example I-2. (A) It is a perspective view of the bonding jig which concerns on manufacture example I-8. (B) It is sectional drawing of the bonding jig which concerns on manufacture example I-8. (A) It is a perspective view of the bonding jig | tool provided with the slipperiness which concerns on manufacture example I-8. (B) It is sectional drawing of the bonding jig | tool provided with the slipperiness which concerns on manufacture example I-8. It is a schematic diagram which shows an example of the bonding jig | tool which concerns on embodiment of specification 4th invention. It is a photograph of an example of the bonding jig | tool which concerns on embodiment of specification 4th invention. It is explanatory drawing (photograph) of the bubble removal process in manufacture example I-13. It is explanatory drawing of the manufacturing process bonding method (process A1) of a longitudinal groove roll with an adhesive. It is explanatory drawing of the manufacturing process coating method (process A2) of a vertical groove roll with an adhesive material. It is explanatory drawing of the flow (in the case of TD direction high diffusion) of the manufacturing process B of a half slit sheet. It is explanatory drawing of the flow (in the case of MD direction high diffusion) of the manufacturing process C of a half slit sheet. It is explanatory drawing of process C2 (marking simultaneously with a sheeting (sheet | leaf) from a roll). It is explanatory drawing of process C3 (B3 is also substantially the same) details (half slit process to a sheet | seat sheet). It is explanatory drawing of process C4 (The half slit strip of both ends for dimensional accuracy adjustment is removed (slit white peeling)). It is explanatory drawing of the flow (rotary die method) of the manufacturing process D1 of a half slit small volume roll. Cutting process diagram D2 for small slit rolls (sheet cutting for rolls) It is explanatory drawing of marking process D3 (marking with respect to a sheet | seat sheet) of a half slit longitudinal groove sheet. It is explanatory drawing of the curvature direction of a suitable sheet | seat. It is explanatory drawing of the slit depth which reaches a suitable heavy peeling separator. It is explanatory drawing of the slit and strip deviation 1 which reach a heavy peeling separator. It is explanatory drawing of the slit and strip gap 2 which reach a heavy peeling separator. It is explanatory drawing of a Lambert LED. It is the schematic of high diffusion LED. It is a graph showing the light emission characteristic of the light which injected into the light-guide plate from LED. It is the schematic diagram which showed the spreading | diffusion inside the light-guide plate of the light which injected diagonally with respect to the light-incidence surface which does not have an uneven structure on the surface. It is the schematic diagram which showed the spread within the light-guide plate of the light which injected diagonally with respect to the light-incidence surface which has an uneven structure on the surface. 1 is a schematic diagram illustrating an embodiment of the present invention using a high diffusion LED. FIG.

Specific embodiments of the light guide plate that can be used in the present invention are as follows.
[1]
A light exit surface, a facing surface facing the light exit surface, and at least one light incident surface sandwiched between the light exit surface and the facing surface, wherein the at least one light incident surface is an opening or A light guide plate having a plurality of concave portions or convex portions having an anisotropic shape whose bottom surface is long in a direction perpendicular to the light exit surface.
[2]
A substrate, an adhesive layer laminated on at least one end surface of the substrate, and a plurality of recesses laminated on the adhesive layer and having an anisotropic shape with an opening or a bottom surface extending in one direction on the surface, or The light guide plate according to [1], including a layer having a convex portion.
[3]
The light guide plate according to [1] or [2], wherein the adhesive layer is made of a material having a storage elastic modulus G ′ at 100 ° C. of 10,000 to 45,000 Pa.
[4]
The layer having a plurality of recesses or projections having an anisotropic shape with an opening or bottom surface extending in one direction on the surface has a base film layer and an anisotropic shape with an opening or bottom surface extending in one direction on the surface. It consists of a resin layer having a plurality of recesses or protrusions,
A resin layer having a plurality of recesses or protrusions having an anisotropic shape with an opening or bottom surface extending in one direction on the surface,
Photopolymerizable resin containing (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group: 70 to 99.9% by mass, and (B) photopolymerization initiator: 0.1 to 30% by mass Including a cured product of the composition,
Any of [1] to [3], wherein (A) the addition polymerizable monomer having at least one terminal ethylenically unsaturated group includes a compound having a structure represented by the following general formula (I) having a biphenyl group: The light guide plate according to claim 1.
Formula (I)
(In the formula, R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.)
[5]
The light guide plate according to [4], wherein the compound having a structure represented by the general formula (I) has a structure represented by the following general formula (II).
Formula (II)
(In general formula (II), R represents a hydrogen atom or a methyl group, A independently represents an alkylene group having 1 to 4 carbon atoms, and n represents an integer of 1 to 3).
[6]
The adhesive layer and the surface having a plurality of recesses or protrusions having an anisotropic shape with an opening or bottom surface extending in one direction on the surface have a slipperiness-imparting layer made of a slip-providing material on the surface, Bonded to one end surface of the base material using a bonding jig having a shape following layer made of a material having a shape following property and having a rubber hardness of 10 to 70 located inside the slipperiness-imparting layer The light guide plate according to any one of [2] to [5].
[7]
The adhesive layer and a layer having a plurality of recesses or protrusions having an anisotropic shape having a long opening or bottom surface in one direction on the surface were bonded to one end surface of the substrate by the following bonding method. The light guide plate according to any one of [2] to [6]:
A laminated body in which an adhesive layer and a layer having a plurality of recesses or protrusions having an anisotropic shape with an opening or a bottom surface extending in one direction on the surface are laminated, and the thickness of the one end face of the substrate Preparing a laminate having substantially the same or narrower width; and
A laminating step in which the adhesive layer of the laminate is opposed to the one end surface, and the laminate is laminated on the one end surface;
A bonding jig comprising a member having a shape following property, while applying pressure on a layer having a plurality of concave portions or convex portions having an anisotropic shape with an opening or a bottom surface extending in one direction on the surface. A close contact process that is traced at least once in the longitudinal direction of the end face;
A laminating method.
[8]
Diffusion in a direction perpendicular to the one direction when light rays are incident on the surface having a plurality of recesses or protrusions having an anisotropic shape whose opening or bottom is long in one direction from the normal direction. The light guide plate according to any one of [1] to [7], wherein the angle is 30 ° to 120 °.
[9]
The entire light incident surface has anisotropic light diffusion characteristics in which the diffusion angle of incident light from the normal direction in the longitudinal direction of the incident surface is greater than the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface. And
The light emission pattern curve of the entire light incident surface with the horizontal axis representing the emission angle of the light emitted from the normal direction of the light incident surface in the longitudinal direction of the light incident surface and the vertical axis representing the intensity appears in the light emission pattern curve. When compared with a normal distribution curve passing through a total of three points: one peak point where the intensity of the emitted light is the peak intensity and two intermediate points where the intensity of the emitted light is half of the peak intensity, the following conditions 1. And / or condition 2. The light guide plate according to any one of [1] to [8], wherein:
Condition 1. The range of the emission angle where the intensity of the emitted light is 3/4 or more of the peak intensity is narrower than the normal distribution curve.
Condition 2. The range of the emission angle where the intensity of the emitted light is 1/10 or more of the peak intensity is wider than the normal distribution curve.

[10]
The light guide plate according to any one of [1] to [9], wherein the light exit surface and / or the opposing surface has a groove structure substantially parallel to a normal direction of the light incident surface.
[11]
The groove structure is a lenticular lens shape or a plurality of random grooves [9]
The light guide plate described in 1.

  An embodiment of the light guide plate of the present invention will be specifically described below with reference to FIG. 1 showing a schematic diagram of an example thereof.

The light guide plate 1 of the present invention has a light exit surface 11, a facing surface facing the light exiting surface, and at least one light incident surface 12 sandwiched between the light exiting surface and the facing surface.
In the light guide plate of the present invention, light from a light source arranged in the vicinity is incident on the light guide plate 12 from the light incident surface 12, is repeatedly reflected inside the plate and guided, and the guided light faces the light output surface. The light exits from the light exit surface 11 toward the light exit surface 11 by an opposing surface (not shown).

  In order to reduce luminance unevenness, the light guide plate has a plurality of concave portions or convex portions 13 having an anisotropic shape in which the opening portion or the bottom surface is long in the direction perpendicular to the light exit surface, on the light incident surface 12. In the light guide plate 1 of FIG. 1, the plurality of recesses or projections having an anisotropic shape whose opening or bottom is long in the direction perpendicular to the light exit surface are grooves substantially perpendicular to the light exit surface 11.

  When the angle between the major axis of the opening (bottom) of the recess (convex) and the direction perpendicular to the light exit surface is 40 degrees or less (even if it is not 0 degree), the opening of the recess (convex) (Bottom surface) shall be “having a long anisotropic shape in the direction perpendicular to the light exit surface”, but the length of the opening (bottom surface) of the recess (convex portion) and the direction perpendicular to the light exit surface. The angle is preferably 10 degrees or less, more preferably 8 degrees or less, more preferably 6 degrees or less, more preferably 4 degrees or less, and most preferably 0 degrees. Here, the major axis of the opening (bottom surface) refers to the long side of the circumscribed rectangle that minimizes the area circumscribing the opening (bottom surface).

  Concave part (convex part) in which the shape of the opening (bottom surface) is other than the anisotropic shape long in the direction perpendicular to the light exiting surface (for example, the opening (bottom surface) is isotropic such as a circle) There may be a shape or an opening (bottom surface) having an anisotropic shape, but the major axis is not parallel to the direction perpendicular to the light exit surface. However, the sum of the areas of the openings (bottom surfaces) of the recesses (projections) having an anisotropic shape with the opening (bottom surface) long in the direction perpendicular to the light exit surface is the opening of the other recesses (projections). It is preferable to exceed the total area of (bottom surface).

  The ratio of the major axis to the minor axis (major axis / minor axis) of the anisotropic shape is not limited, but is preferably 2 or more, more preferably 10 or more. Here, the minor axis and the major axis refer to the short side and the long side of the circumscribed rectangle having the smallest circumscribed area, respectively.

  The anisotropic shape is not limited, and specific examples thereof include a straight line (groove) as shown in FIG. 1 and a substantially elliptical shape as shown in FIG.

  The shape of the opening surface (bottom surface) of the concave portion (convex portion) can be determined by observing an arbitrary portion of the light incident surface with a microscope (such as a scanning electron microscope or a laser confocal microscope).

  The pitch in the direction parallel to the light exit surface of the recesses (projections) is not limited, but the average pitch is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The average pitch is preferably 580 nm (the central wavelength of visible light) or more, and more preferably 780 nm (the entire visible light region) or more.

  Since the light emitting surface size (width) of a commonly used point light source is about several millimeters, if the average pitch is set to such a value, a sufficient number of concave or convex portions are allocated to the light emitting surface of the point light source. This eliminates the need to strictly determine the alignment accuracy between the light source and the light guide plate. Further, when the average pitch is set to such a value, the claw or the like is hardly caught on the concave portion or the convex portion during handling, and the handling property is improved. Furthermore, since the light diffused by the light guide plate included in the surface light source device of the present invention is visible light (an electromagnetic wave of 380 nm to 780 nm), the average pitch is the above in order to sufficiently exhibit the diffusion effect by the concave portion or the convex portion. It is preferable that the value is as follows.

Here, the pitch in the direction parallel to the light exit surface of the concave portion (convex portion) means the adjacent valley bottom (in the case of the concave portion) or peak (in the case of the convex portion) in an arbitrary cross section parallel to the light exit surface of the light incident surface. The horizontal distance between them (the distance in the direction parallel to the light incident surface) (see FIG. 13). If the valley bottom (mountain peak) is flat, the pitch is determined with the center as the valley bottom (peak peak).
Further, the average pitch in the direction parallel to the light exit surface of the concave portion or the convex portion is the average pitch of the concave portion (convex portion) present at 100 μm arbitrarily extracted from an arbitrary vertical cross section parallel to the light exit surface of the light incident surface. Value.

  The (average) pitch in the direction parallel to the light exit surface of the concave portion (convex portion) is observed and measured with a microscope (such as a scanning electron microscope or a laser confocal microscope) in an arbitrary cross section parallel to the light exit surface. Can be determined by

There is no limitation on the size (depth / height) of each recess (projection).
For example, the minor axis of the opening (bottom surface) may be 580 nm to 100 μm, 780 nm to 60 μm, or 1 to 20 μm. Further, the major axis of the opening (bottom surface) may be, for example, 5 μm or more and 2 cm or less.
The depth (height) may be, for example, 500 nm to 50 μm, 700 nm to 30 μm, or 5 to 10 μm. The average depth (height) of the concave portion or convex portion is also preferably 500 nm to 50 μm, more preferably 700 nm to 30 μm, and further preferably 5 to 10 μm.

Here, the depth (height) of the concave portion (convex portion) is defined between the peak of the higher mountain and the valley bottom of the concave portion among the peaks on both sides constituting each concave portion in an arbitrary cross section of the light incident surface. The vertical distance (the distance in the direction perpendicular to the light incident surface) (the difference in elevation between the peak and the valley bottom) between the valley bottom of the lower valley and the peak of the peak among the valleys on both sides constituting the protrusion. (See FIG. 13) The average depth (height) of the concave portion or convex portion is the depth (height) of the concave portion (convex portion) existing at 100 μm arbitrarily extracted from an arbitrary vertical cross section of the light incident surface. The average value of
The size of the concave portion (convex portion) can be determined by observing and measuring an arbitrary portion of the light incident surface with a microscope (such as a scanning electron microscope or a laser confocal microscope).

  However, when the shape of the recess (projection) is a groove (ridge), the length is preferably larger than the length of the light emitting surface of the point light source in the thickness direction of the light guide plate. That is, it is preferable that the length of the groove (畝) is not less than the size of the light emitting surface of the point light source and not more than the thickness of the light guide plate. In FIG. 1, the groove has a length that traverses the light incident surface in the thickness direction of the light guide plate (from the light exit surface to the opposite surface), but the length of the groove (畝) is not necessarily light incident. It does not have to cross the plane.

The plurality of recesses (projections) is not a periodic structure as in the prior art, but the shape, size (depth, height) of the plurality of recesses (projections) and the pitch in the direction 15 parallel to the light exit surface It is preferable that at least one of them is randomly (irregularly) different because luminance unevenness reduction effect (especially hot spot reduction) is improved.
Here, being different at random means that a value (3 sigma) obtained by multiplying a standard deviation calculated from a plurality of measured values exceeds 10% of the average value.

  There is no particular limitation on the region where the concave portion or the convex portion on the light incident surface is arranged, and it can be appropriately determined according to the light emission distribution and arrangement of the light source used in combination with the light guide plate. That is, the light guide plate included in the surface light source device of the present invention may have a portion (region) having no concave portion or convex portion on the light incident surface. But it is preferable that the recessed part or convex part is arrange | positioned at least in the area | region facing the light emission surface of a light source.

  Moreover, although there is no limitation in the density of a recessed part or a convex part, about the area | region which opposes the light emission surface of a light source among the light-incidence surfaces of a light-guide plate, the sum total of the area of the opening part (bottom surface) of a recessed part (convex part). Occupy 25% or more (more preferably 50% or more, still more preferably 70% or more) of the region.

Specific examples of the plurality of concave portions or convex portions are shown in FIGS. 2, 3, and 24 </ b> A to 24 </ b> J.
In the examples of FIGS. 2 and 3, the concave portion or the convex portion is a groove. The plurality of grooves (groove structure) in FIG. 2 is anisotropic with a diffusion angle in a direction perpendicular to the groove (defined by FWHM described later) of 60 degrees and a diffusion angle in a direction parallel to the grooves of 1 degree. Has diffusion properties. The groove structure of FIG. 3 has anisotropic diffusion characteristics in which the diffusion angle in the direction perpendicular to the groove is 30 degrees and the diffusion angle in the direction parallel to the groove is 1 degree.
The diffusion angles, average pitches (average pitch in the direction perpendicular to the major axis direction (grooves) of the openings of the recesses), and average depths of FIGS. 24A to 24J are shown in Table 1. In Table 1, “horizontal” means a direction perpendicular to the direction of the major axis of the opening of the recess (perpendicular to the groove), and “vertical” means a direction parallel to the major axis of the opening of the recess ( The direction (parallel to the groove).

Table 1

  Another specific example of a plurality of concave portions or convex portions is shown in FIGS. In all the examples of FIG. 3, the concave portion or the convex portion is a groove. The plurality of grooves (groove structure) in FIG. E3 (a) has an anisotropic diffusion with a diffusion angle in a direction perpendicular to the groove (described later) of 83 degrees and a diffusion angle in a direction parallel to the grooves of 3 degrees. Has characteristics. The groove structure (b) has anisotropic diffusion characteristics in which the diffusion angle in the direction perpendicular to the groove is 75 degrees and the diffusion angle in the direction parallel to the grooves is 0.2 degrees. The groove structure (c) has anisotropic diffusion characteristics in which the diffusion angle in the direction perpendicular to the groove is 65 degrees and the diffusion angle in the direction parallel to the grooves is 7 degrees.

A moth-eye structure may be provided on the surface of the plurality of concave portions or convex portions for the purpose of reducing reflection on the light incident surface and efficiently using incident light. Here, the “moth eye structure” means that convex portions having substantially the same shape with a height of 1 μm or less are substantially periodic (for example, a square lattice shape, a rectangular lattice shape, a square quadrangular lattice shape, a triangular lattice shape (honeycomb)). Alternatively, it means a fine uneven structure provided in a hexagonal lattice pattern with a pitch of about 50 to 500 nm. Here, the “fine concavo-convex structure” refers to concavo-convex whose average height is 1/10 or less of the average depth (height) of the plurality of concave portions (convex portions). The height may be 50 to 500 nm or 100 to 300 nm.
The concavo-convex structure is preferably composed of a plurality of convex portions. There is no limitation in the shape of each convex part, For example, a tent shape, a cone shape, a bell shape, a polygonal pyramid shape, a hemispherical shape etc. are mentioned, It is preferable that the average height is 1 micrometer or less.
Specific examples of the moth-eye structure and the recess (groove) having the moth-eye structure on the surface are shown in FIGS. 16 and 17, respectively.

  A plurality of concave portions or convex portions (hereinafter sometimes referred to as “concave structure”) having an anisotropic shape whose opening or bottom is long in the direction perpendicular to the light exit surface on the light incident surface of the light guide plate of the present invention. There is no limitation on the method of forming the film. For example, (1) a method of injection molding a light guide plate using a mold having a concavo-convex pattern corresponding to the concavo-convex structure, (2) a light guide plate (base material) using a transfer mold having a concavo-convex pattern corresponding to the concavo-convex structure And (3) a method of bonding a layer having a concavo-convex structure on the surface to a light guide plate (base material) using a translucent adhesive (adhesive) or the like. Etc. can be used.

  It should be noted that the effect of the present invention is not exhibited unless the layer having the concavo-convex structure is attached to the light incident surface with a transparent optical adhesive or the like and integrated with the light guide plate. In other words, simply disposing the layer having the concavo-convex structure between the light incident surface of the light guide plate and the light source diffuses the incident light inside the light guide plate to a wide angle (and more, hot spots and other It is impossible to eliminate luminance unevenness derived from the point light source.

  As a method of (1), for example, a stamper having a concavo-convex pattern corresponding to the concavo-convex structure is disposed at a position corresponding to the light incident surface of a mold for forming the light guide plate, and the light guide plate having the concavo-convex structure is injection molded from the beginning. can do. This method is suitable for manufacturing a light guide plate for a surface light source device used for a relatively small (about 32 type or less) image display device.

  As a method of (2), for example, after forming a light guide plate (base material) (raw sheet for light guide plate production) that does not have a concavo-convex structure by extrusion molding or cast molding, a light incident surface (light incident surface) The concavo-convex structure can be transferred using a transfer mold having a concavo-convex pattern corresponding to the concavo-convex structure on the surface.

  FIG. 4 shows a specific example of this method. In the method of FIG. 4, a plurality of transparent substrates 41 cut to a predetermined size are stacked, and light incident on the transparent substrate while heating a transfer roller 42 having a concavo-convex pattern corresponding to a concavo-convex structure (here, a groove structure) on the surface. The uneven structure is transferred by pressing against the surface. According to this method, since transfer can be performed collectively on a plurality of light guide plates, mass production is possible and quality is improved.

  The specific procedure of the method (3) is not limited, and an adhesive layer and a layer having a concavo-convex structure on the surface may be sequentially bonded to the substrate (the layer having a concavo-convex structure on the surface is a transparent base film). When the layer and the resin layer having a concavo-convex structure on the surface, the adhesive layer may be bonded with a transparent base film layer and a resin layer, or the adhesive layer, the transparent base film layer, The resin layers may be bonded in this order). Alternatively, a laminate in which an adhesive layer and a layer having a concavo-convex structure are bonded in advance is prepared, and this may be bonded to a substrate.

In the case of sequentially bonding an adhesive layer and a layer having a concavo-convex structure on the surface to the substrate, a method of bonding an adhesive layer to the substrate, and a method of bonding a layer having a concavo-convex structure on the surface thereon There is no limitation.
Since the adhesive layer itself is sticky, each layer may be simply laminated, and after lamination, the layers are brought into close contact with each other by ventilating the air using a tool such as a spatula or a highly rigid roller. May be. As such a jig, a bonding jig according to the fourth invention of the present specification described later (for example, a shape having a slipperiness imparting layer made of a slippery imparting material on the surface and positioned inside the slipperiness imparting layer) It is preferable to use a bonding jig having a shape following layer made of a material having a following property and a rubber hardness of 10 to 70).

  According to the study by the present inventors, it was found that when the ratio of the portion where the air layer is interposed between the layers in the laminated region is 10% by area or less, delamination hardly occurs under high temperature and high humidity. . Therefore, it is very effective to use a jig to evacuate the air between the layers until the ratio of the portion where the air layer is interposed is 10 area% or less.

  Using an adhesive layer with a release sheet laminated on one side, sticking the adhesive layer to the substrate, venting as necessary, then peeling off the release sheet and forming a concavo-convex structure on the surface You may make it stick the layer which has.

  Also, prior to the bonding of the adhesive layer on the substrate, or the bonding of the layer having an uneven structure on the surface thereof, the uneven structure on the substrate and / or the adhesive layer, the adhesive layer and / or the surface. After the surface molecular bond is cut by applying a surface treatment such as excimer UV treatment or corona treatment to the layer having, the bonding strength can be improved by immediately bringing them into close contact.

In the case of preparing a laminate in which an adhesive layer and a layer having a concavo-convex structure on the surface are prepared in advance and pasting the laminate on a substrate, the following method can be employed. This method will be described in detail in the description related to the fourth invention of this specification described later.
A laminate in which an adhesive layer and a layer having a concavo-convex structure on the surface are laminated, and a step of preparing a laminate having a width substantially equal to or narrower than the thickness of one end surface of the substrate;
A laminating step in which the adhesive layer of the laminate is opposed to the one end surface, and the laminate is laminated on the one end surface;
An adhesion step comprising a member having a shape following property, while applying pressure on the surface having a concavo-convex structure on the surface, and an adhesion step of tracing one or more times in the longitudinal direction of the one end surface;
A laminating method.

As a specific example of a method of preparing a laminate in which an adhesive layer and a layer having a concavo-convex structure on the surface are previously prepared and affixing the laminate to a substrate, a. A sealing mold, and b. There are two types of tape-type methods.
a. Seal type For example, an ultraviolet curable resin layer is applied on a transparent base film made of polyethylene terephthalate, polycarbonate, polystyrene, etc., and an uneven structure is formed on the ultraviolet curable resin layer by a method using a speckle pattern described later. Then, a layer having a concavo-convex structure is formed on the surface. Although there is no limitation in the thickness of a base film, it can be 20-250 micrometers, for example, Preferably it is 50-125 micrometers.

  Next, an adhesive (adhesive) is applied to the surface of the base film opposite to the surface on which the concavo-convex structure is formed, and a release film made of polyethylene terephthalate or the like is bonded thereto, or a release film is attached. A multilayer film in which the adhesive side is covered with a release film is produced by bonding the adhesive layer of the adhesive film. A specific example of the layer structure of such a multilayer film is shown in FIG. 5a and 5b in FIG. 5 are both multilayer films provided with a release film on one side. In the multilayer film 5a, a release film 51, an adhesive layer 52, a base film 53, and a resin layer 54 having a concavo-convex structure (here, a groove structure) are laminated on the surface in order from the bottom. Further, in the multilayer film 5b, an adhesive layer 55 and a mount film layer 56 are further provided on the resin layer 54 on which the concavo-convex structure is formed, and a release film 51, an adhesive layer 52, a base film 53, A resin layer 54 having an uneven structure, an adhesive layer 55, and a mount film 56 are laminated. The release film 51 and the mount film 56 serve as a seal mount or a protective film during the manufacture of the light guide plate, and the thickness thereof is not limited. For example (depending on the material), 20 to 100 μm. It can be. However, in order to perform the half-cut processing more easily, the mount film is preferably 50 μm or more, and more preferably 75 μm or more. Moreover, the thickness of the contact bonding layer 52 can be 10-100 micrometers, for example. When considering the balance between performance and cost, it is preferably about 15 to 50 μm, and more preferably about 20 to 25 μm.

  Next, this multilayer film is cut in accordance with the length (width) of the light incident surface of the light guide plate. Next, in the case of the multilayer film 5a, only the release film 51 is left, and in the case of the multilayer film 5b, the mount film 56. The adhesive layer 55 is left, and the remaining layers are cut into half the same width as the thickness of the light incident surface (half-cut), thereby forming a film with an uneven structure having the same size as the light incident surface of the light guide plate ( A seal sheet is produced in which a plurality of uneven structure seals) are formed on the release film 51 (in the case of the multilayer film 5a) or the mount film 56 (in the case of the multilayer film 5b). In addition, as described above, in the case of the multilayer film 5a, since the blade of the cutting means enters from the side of the layer on which the concavo-convex structure is formed during the half-cut process, there is an advantage that there is less risk of the concavo-convex structure being broken, On the other hand, in the case of the multilayer film 5b, the blade of the cutting means enters from the side of the adhesive layer 52 during the half-cut process, so that the adhesive layer can be reliably cut and the adhesives (adhesives) stick together again. There is an advantage that the problem of “threading” is less likely to occur. Examples of the half-cutting method include, but are not limited to, a method of putting a Thomson blade in a cutting direction, a method of rolling a roll blade in a cutting direction, and a method of burning to a desired depth using a laser. In addition, there exists an advantage that cutting waste does not generate | occur | produce when a laser is used. A schematic front view of the seal sheet thus produced is shown in FIG. In FIG. 6, each vertical line indicates a groove 61.

  Then, in the manufacturing process of the light guide plate and the assembly process of the surface light source device having the light guide plate, in the case of the multilayer film 5a, the films having the uneven structure (uneven structure seal) are peeled off from the release film 51 one by one and bonded. It is bonded to the light incident surface of the light guide plate (base material) via the layer 52. In the case of the multilayer film 5 b, the film having the concavo-convex structure (the concavo-convex structure seal) is peeled off from the adhesive layer 55 one by one, and then the peelable film 51 is peeled off and bonded to the light incident surface through the adhesive layer 52. Finally, if necessary, the air between the film and the light incident surface may be brought into close contact by removing with a roller or the like.

  Prior to bonding, surface adhesion such as excimer UV treatment or corona treatment is applied to the adhesive layer 52 and / or the light incident surface to cut the surface molecular bonds, and immediately thereafter, the adhesive layer 52 and the light incident surface are formed. Bonding strength can also be improved by the close contact. Furthermore, by using such a surface treatment, it is possible to bond the base film of the film having a concavo-convex structure and the light guide plate without using an adhesive, thereby reducing the cost and improving the reliability. Can do.

  According to this seal-type method, the bonding operation to the light incident surface is facilitated, and the number of used (bonded) seals can be easily managed, so that the light guide plate can be easily manufactured. Furthermore, transportation of the light guide plate manufacturing material is facilitated.

  When manufacturing the seal sheet, the multilayer film (5a, 5b) is cut shorter than the length (width) of the light incident surface of the light guide plate, and two or more multilayer films (seal) are assembled when assembling the surface light source device. ) May be bonded to the light incident surface. At this time, the multilayer film (seal) covers 2 mm or more outside (up and down, left and right) from the area facing the light emitting surface of the light source on the light incident surface (the gap or seam between the films is in the area facing the light emitting surface). It is preferable to position and bond together.

b. Tape type b. A tape-type method will be described with reference to FIG.
a. In the same manner as in the case of the seal type, a multilayer film 71 having a layer in which an uneven structure is formed is manufactured. Next, this is cut into the same width as the thickness of the light incident surface to form a plurality of tapes, each wound on a reel (not shown) and processed into a roll 72. A specific example of the reel is shown in FIG. At this time, as shown in FIG. 25, it is preferable to wind up with a reel having a structure sandwiched between two disks so that the wound tape does not cause axial misalignment. The diameter of the wound tape is preferably smaller than the outer diameter of the disk.

  Then, in the manufacturing process of the light guide plate and the assembly process of the surface light source device and the illuminating device having the light guide plate, a tape (tape film) having a layer having a concavo-convex structure is fed out from the roll 72 to enter the light guide plate After cutting to the length of the light surface, it is bonded to the light incident surface, or after being bonded to the light incident surface, it is cut to the length of the light incident surface. For bonding, a. The same method as described in the seal-type method can be adopted.

  According to this method, the length for cutting the tape may be determined when the tape is bonded to the light guide plate. Therefore, one type of roll (a roll of a tape-like film having a layer on which a concavo-convex structure is formed) can be of various sizes. Can be used for manufacturing a light guide plate having a large thickness, and the versatility of the roll is high. Further, it is easy to automate and speed up the process of bonding the multilayer film 71 to the light guide plate.

  The concavo-convex pattern or concavo-convex structure corresponding to the concavo-convex structure is applied to the mold (stamper), transfer mold (transfer roller) used in the methods (1) and (2) or the film used in the method (3). There is no limitation on the forming method. For example, it may be formed by machining such as cutting or sandblasting, or may be formed by laser speckle pattern exposure. The method using speckle pattern exposure is suitable for forming a fine three-dimensional structure of about 10 μm or less, which is difficult by machining, and it is easy to obtain an appropriate irregularity.

  Specifically, when speckle pattern exposure is used, a random uneven structure can be formed as follows.

  For example, a random speckle pattern or a striped speckle pattern is generated by interference exposure using laser light, and this is irradiated to a photosensitive material such as a photoresist. Next, when the exposed photosensitive material is developed by a known method, a random uneven structure corresponding to the speckle pattern is formed on the photosensitive material.

  Note that the random speckle pattern or striped speckle pattern can be generated by, for example, diffusing laser light with a diffusion layer having strong anisotropy. Normally, when the laser beam is diffused by the diffusion layer and irradiated to the exposed surface, speckles are generated as circular unevenness. However, if the diffusion layer has a strong anisotropy, the speckles have a speckled or striped pattern. be able to. Furthermore, a desired random spot / striped pattern can be obtained by appropriately changing the wavelength of the laser light, the conditions for diffusing the laser light, and the like. Specifically, it can be generated by the method disclosed in paragraphs 0047 to 0057 of JP-T-2004-508585.

  The metal mold or transfer mold having a concavo-convex pattern corresponding to the concavo-convex structure is a sub-master mold formed by the above-described concavo-convex structure, and the metal is deposited on the sub-master mold by a method such as electroforming. It can be produced by transferring a concavo-convex pattern corresponding to the concavo-convex structure.

  In addition, a method for producing a fine concavo-convex pattern using a speckle pattern by interference exposure is well known. Yes.

When the above method (3) is adopted as a method for forming a plurality of concave portions or convex portions on the light incident surface of the light guide plate, the structure of the light guide plate is laminated on at least a part of the base material. And a layer having a plurality of recesses or protrusions on the surface laminated thereon (a layer having a concavo-convex structure on the surface).
Here, the region where the adhesive layer and the layer having the concavo-convex structure are provided on the surface is a light incident surface.
If the adhesive layer and the layer having a concavo-convex structure on the surface protrude outside the base material, when assembling a surface light source device or the like using the light guide plate of the present invention, it will come into contact with and interfere with other members. Since there is a risk that the layer having the concavo-convex structure may be peeled off or the other members may be damaged, it is preferable that these are within the plane.

  In the place where the adhesive layer of the base material and the layer having the concavo-convex structure on the surface are laminated, the microscopic air to escape the bubbles generated between the base material and the adhesive layer when the light guide plate is used under high temperature and high humidity etc. One or a plurality of grooves may be formed. There is no limitation on the width, cross-sectional shape, depth, and the like of such a groove, but the width is preferably 0.5 mm or less, more preferably 0.3 to 0.01 mm. Moreover, the depth can be 0.5-0.01 mm, for example. Although the length of the groove is not limited, it is preferable that the groove is crossed or longitudinally crossed over the region where the adhesive layer is laminated.

The material of the base material is not particularly limited as long as it is translucent. For example, it is generally used as a material for optical parts such as polymethyl methacrylate, polycarbonate, polystyrene, and methyl methacrylate-styrene copolymer. A high molecular weight material (for example, a total light transmittance of 90% or more and a haze of 1.0 or less) can be used.
In addition, base materials include organic and inorganic dyes and pigments, matting agents, heat stabilizers, flame retardants, antistatic agents, antifoaming agents, color stabilizers, antioxidants, UV absorbers, as necessary. Additives such as impurity scavengers, thickeners, surface conditioners, and mold release agents may be contained within a range not impairing the object of the present invention.

An example of a cross section of such a light guide plate is shown in FIG. E4. In FIG. E4, E41 is a substrate, E42 is an adhesive layer, and E43 is a layer having a concavo-convex structure on the surface.
The adhesive layer plays a role of fixing a layer having a concavo-convex structure on the surface to the base material. The material constituting the adhesive layer preferably has a storage elastic modulus G ′ at 100 ° C. of 40,000 to 180,000 Pa. When the light guide plate is incorporated into a surface light source device or a television receiver, it is used in a high temperature environment where the temperature is locally raised to about 100 ° C. or a humid environment where the temperature is about 95 RH% due to heat generated by the LED light source. When a conventionally used adhesive layer is used, adhesion of a layer having a concavo-convex structure on the surface to the substrate is not sufficient. Therefore, when it is used for a long period of time, bubbles are generated between layers having a concavo-convex structure on the surface of the substrate, or a layer having a concavo-convex structure on the surface is peeled off. However, as a result of intensive studies by the present inventors, such a problem can be solved by using a material having a storage elastic modulus G ′ at 100 ° C. of 40,000 to 180,000 Pa as a material constituting the adhesive layer. There was found.
The material constituting the adhesive layer is not limited except that the storage elastic modulus G ′ at 100 ° C. is 40,000 to 180,000 Pa, and generally used adhesives can be used. Examples of such adhesives include hot melt adhesives, thermosetting adhesives, pressure sensitive adhesives, energy ray curable adhesives, hygroscopic adhesives, dry adhesives, UV curable adhesives, Examples thereof include a polymerization type adhesive, a two-component reaction type adhesive, and an anaerobic type adhesive. Among these, a pressure-sensitive adhesive (adhesive) is most preferable from the viewpoint of workability.
In particular, according to the studies by the present inventors, when a pressure-sensitive adhesive having a storage elastic modulus G ′ at 100 ° C. of 40,000 to 180,000 is used, the substrate-adhesive layer and the adhesive layer-surface are used. It has been found that peeling between layers having a concavo-convex structure hardly occurs. Therefore, it is preferable to use such a material for the adhesive layer.
The storage elastic modulus at 100 ° C. of the material of the adhesive layer is more preferably 40,000 to 120,000 Pa, still more preferably 65,000 to 120,000 Pa, and particularly preferably 65,000 to 95,000 Pa. If the storage elastic modulus is too small, peeling or the like after sticking tends to occur, and if it is too large, the adhesiveness is inferior. Moreover, when the storage elastic modulus is too small, foaming occurs at the time of attachment when the substrate is an acrylic resin, which is not preferable.
The reason why peeling is difficult to occur when the storage elastic modulus G ′ at 100 ° C. is 40,000 to 180,000 Pa is not clear, but the high temperature resulting from the difference in coefficient of thermal expansion between the base material and the layer having an uneven structure on the surface. It is presumed that this is because the strain of time can be absorbed. However, the mechanism does not depend on this.

Here, the storage elastic modulus G ′ at 100 ° C. in the present invention means a value obtained by averaging the storage elastic modulus G ′ at 90 ° C. or more and less than 110 ° C. based on the results obtained by measurement under the following conditions. As the measuring device, for example, ARES manufactured by TA Instruments Inc. can be used.
-Deformation mode: Torsion-Measurement frequency: Constant frequency 1 Hz
-Rate of temperature increase: 5 ° C / min-Strain: 0.2%
・ Measurement temperature: Measured from near the glass transition temperature of the adhesive to 200 ℃ ・ Measurement part shape: Parallel plate 8mmφ
・ Sample thickness: 0.8-1mm
・ Pretreatment: Vacuum drying at a temperature of 50 ° C. and a degree of vacuum of −0.02 MPa for 30 minutes.

The storage elastic modulus G ′ at 100 ° C. in the present invention has a one-to-one correlation with the value (G ₀ ′) obtained in the same manner except that the following conditions are adopted as measurement conditions. Yes. The correspondence is shown in FIG. E19.
Deformation mode: Torsion Measurement frequency: Constant frequency 1 rad / s
-Rate of temperature increase: 5 ° C / min-Strain: 2%
・ Measurement temperature: Measured from near the glass transition temperature of the adhesive to 200 ℃ ・ Measurement shape: Parallel plate 25mmφ
・ Sample thickness: 0.8-2mm
・ Pretreatment: None

In terms of optical properties, the material of the adhesive layer is preferably such that the total light transmittance of the adhesive layer is 90% or more and the haze is 1.0 or less.
Furthermore, since the adhesive layer is disposed in the vicinity of the light source when the light guide member is incorporated in a surface light source device, an illumination device, or the like, it is also preferable that the adhesive layer can withstand the influence of heat from the light source. .

  From the viewpoints described above, a preferable material for the adhesive layer is a (meth) acrylic pressure-sensitive adhesive (hereinafter simply referred to as “acrylic pressure-sensitive adhesive”) ((meth) acrylic polymer (as a monomer component (meth ) (Polymer containing acrylic acid) as a base polymer (preferably containing 30% by mass, more preferably containing 50% by mass or more)), urethane type adhesives, and rubber type adhesives.

Examples of the rubber-based adhesive include natural rubber, a copolymer of natural rubber and an acrylic component such as methyl methacrylate, a styrene block copolymer and a hydrogenated product thereof, and a styrene-butadiene-styrene block copolymer and Examples thereof include hydrogenated products. Among these, a copolymer of natural rubber and an acrylic component such as methyl methacrylate is preferable.
These may be used singly or in combination of two or more.

As an acrylic adhesive, what was manufactured with the below-mentioned method, a commercially available acrylic adhesive, etc. are mentioned.
Examples of commercially available acrylic adhesives include, for example, MO-3006C (manufactured by Lintec Corporation), MO-3012C (manufactured by Lintec Corporation), 8171 JR (manufactured by 3M Corporation), 8172 JR (3M Corporation). Manufactured), Panaclean PD-S1 (manufactured by Panac Co., Ltd.), MASTACK TR-1801 (manufactured by Fujimori Kogyo Co., Ltd.), MASTAK TR-1802 (manufactured by Fujimori Kogyo Co., Ltd.), CCL / D2-L / T5T5 (manufactured by Fujimori Kogyo Co., Ltd.) New Tac Kasei Co., Ltd.), CCL / D1 / T3T3 (New Tac Kasei Co., Ltd.), EXC10-076 (Toyo Ink Co., Ltd.), LUCIACS CS9621T (Nitto Denko Co., Ltd.), LUCIACS HJ9150W ( Nitto Denko Co., Ltd.), DH425A (manufactured by Sanei Kaken Co., Ltd.), and the like, but are not particularly limited thereto.
For example, when the layer having a concavo-convex structure on the surface is polyethylene terephthalate and the material of the base material is polymethyl methacrylate and used in an environment of 85 ° C., among the above-mentioned adhesives, PD-S1, TR-1801A, CCL / D1 / T3T3, MO-3006C, and EXC10-076 are preferable. The pressure-sensitive adhesive that can withstand even in a high temperature environment of 100 ° C. is PD-S1, TR-1801A, CCL / D1 / T3T3.

As a (meth) acrylic-type polymer which is a base polymer of an acrylic adhesive, for example, 0.1 to 10% by mass of a hydroxyl group-containing monomer or 0.1 to 10% by mass of a carboxyl group-containing monomer is copolymerized ( A (meth) acrylic polymer is particularly preferred.
Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. Among these, it is preferable to use a hydroxyl group-containing monomer having 4 or more carbon atoms in the side chain because heat resistance is improved. These may be used singly or in combination of two or more.
The copolymerization ratio when using the hydroxyl group-containing monomer is preferably 0.1 to 10% by mass, and more preferably 0.3 to 7% by mass. If the content of the hydroxyl group-containing monomer is too small, the long-term durability may be lowered.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid and the like, and acrylic acid and methacrylic acid are particularly preferably used. These may be used singly or in combination of two or more. These carboxyl group-containing monomers are effective from the viewpoint of heat resistance due to improved adhesion and increased cohesive strength.
The copolymerization ratio of the carboxyl group-containing monomer is preferably 0.1 to 5% by mass, more preferably 0.2 to 3% by mass. If the amount of the carboxyl group-containing monomer is too small, the adhesiveness is inferior. If the amount is too large, the adhesive becomes hard and the durability may be inferior.

  In addition to these, as a monomer component of the (meth) acrylic polymer, a (meth) acrylic acid ester-based monomer having an alkyl group can be used. Examples of such (meth) acrylic acid ester monomers having an alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, Pentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isomyristyl (Meth) acrylate and the like. These may be used singly or in combination of two or more. Among these, from the viewpoint of imparting flexibility to the pressure-sensitive adhesive, n-butyl (meth) acrylate is preferably used, and in that case, 30 to 99% by mass is preferably used in the (meth) acrylic polymer. More preferably, it is 50-99 mass%.

Furthermore, you may copolymerize suitably the other monomer (monomer component) which can be copolymerized with a (meth) acrylic-type polymer. Examples of the copolymerizable monomer include vinyl acetate, acrylamide, dimethylaminoalkylamide, acryloylmorpholine, glycidyl acrylate, styrene derivatives such as styrene and α-methylstyrene, and derivatives such as vinyltoluene and α-vinyltoluene. And high refractive index monomers, benzyl (meth) acrylate, naphthyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxybutyl (meth) acrylate, and the like.

  In addition, as the (meth) acrylic polymer, in particular, a (meth) acrylic polymer containing 0.1 to 30% by mass of a carboxyl group-containing monomer and 30 to 99.9% by mass of n-butyl (meth) acrylate as a copolymerization component. Polymers are preferred, and those having a gel fraction adjusted to 30 to 90% by mass are preferred. As described above, the (meth) acrylic polymer can improve both the internal cohesive force and the flexibility of the adhesive layer, and therefore, when used by being bonded to the base material of the light guide member, No peeling from the material.

  The weight average molecular weight of the (meth) acrylic polymer is usually 600,000 or more, preferably 700,000 to 3,000,000. When the weight average molecular weight is too small, durability is poor, and when it is too large, workability is deteriorated.

The production of the (meth) acrylic polymer can employ any known production method such as solution polymerization, bulk polymerization, and emulsion polymerization.
For example, in solution polymerization, a polymerization initiator such as azobisisobutyronitrile (AIBN) is preferably used in an amount of 0.01 to 0.2 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. More preferably, 0.05 to 0.15 parts by mass are used. It can be obtained by reacting at 50 to 70 ° C. for 8 to 30 hours under a nitrogen stream using a polymerization solvent such as ethyl acetate.

Modification treatment can also be performed for the purpose of adjusting the refractive index of the (meth) acrylic polymer thus obtained, increasing the internal cohesive force, and increasing the heat resistance.
As the modification treatment, for example, in the presence of 100 parts by mass of the (meth) acrylic polymer, a monomer different from the monomer component of the (meth) acrylic polymer is 10 to 200 parts by mass, preferably 10 to 100 parts by mass. In addition to the above, the medium may be adjusted as necessary, and a graft polymerization reaction may be performed using 0.02 to 5 parts by mass of peroxide, preferably 0.04 to 2 parts by mass.
Here, the monomer different from the monomer component of the (meth) acrylic polymer is not particularly limited, and benzyl (meth) acrylate, phenoxy (meth) acrylate, naphthyl (meth) acrylate, isobornyl (meth) acrylate High refractive index monomers such as (meth) acrylic acid ester monomers such as styrene derivatives such as styrene and α-methylstyrene, and derivatives such as vinyltoluene and α-vinyltoluene. By using the high refractive index monomer, the refractive index of the (meth) acrylic polymer can be increased.

As a graft polymerization method, in the case of solution polymerization, a necessary monomer and a solvent whose viscosity is adjusted are added to a solution of a (meth) acrylic polymer, followed by nitrogen substitution, and then a peroxide of 0.02 to 5 A part by mass, preferably 0.04 to 2 parts by mass, is added and heated at 50 to 80 ° C. for 4 to 15 hours to carry out a graft polymerization reaction.
If it is emulsion polymerization, add water to adjust the solid content to the aqueous dispersion of (meth) acrylic polymer, add the necessary monomer, and replace with nitrogen while stirring. After the monomer is absorbed into the polymer particles, a water-soluble peroxide aqueous solution is added, and the reaction is terminated by heating at 50 to 80 ° C. for 4 to 15 hours.
Thus, by polymerizing the monomer in the presence of the (meth) acrylic polymer, a homopolymer of this monomer is also produced, but graft polymerization to the (meth) acrylic polymer also occurs. The polymer consisting of the homopolymer is uniformly present in the acrylic copolymer. In this case, if the amount of peroxide used as an initiator is small, it takes too much time for the graft polymerization reaction, and if it is too large, a large amount of monomer homopolymer is generated.

In addition to a base polymer such as a (meth) acrylic polymer, a tackifier such as a tackifier may be appropriately added to the adhesive.
Although it does not specifically limit as said tackifier, A non-colored and transparent thing is preferable. The transparency is preferably a Gardner hue of 1 or less in a 50% by weight toluene solution.
As the tackifier, for example, a tackifier having an aromatic ring and having a refractive index in the range of 1.51 to 1.75 is preferably used. Moreover, it is preferable that the weight average molecular weights of a tackifier are 1000-3000, and it is preferable that a softening point is 90 degrees C or less. If the weight average molecular weight exceeds 3000 or the softening point exceeds 90 ° C., the compatibility with the (meth) acrylic polymer may be reduced, and if the weight average molecular weight is less than 1000, the cohesive strength of the adhesive May decrease.
Specifically, a styrene oligomer, a phenoxyethyl acrylate oligomer, a copolymer of styrene and α-methylstyrene, a copolymer of vinyltoluene and α-methylstyrene,
Examples thereof include hydrogenated products of C9 petroleum resins, hydrogenated products of terpene phenol, and hydrogenated products of rosin and its derivatives. At this time, a tackifier having a softening point of 40 ° C. or lower is used in combination with a use amount of less than 30 parts by mass and a tackifier having a softening point of 50 ° C. or higher being used in combination of 20 parts by mass or more. In terms of surface.
The amount of these tackifiers used is 10 to 150 parts by mass, preferably 20 to 100 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer solid content, and is adjusted to a predetermined refractive index. If the amount is too small, the refractive index will not increase sufficiently, and if it is too large, it will become hard and the adhesiveness will deteriorate, which is not preferable.

A crosslinking agent can be appropriately used for the pressure-sensitive adhesive. In particular, when a (meth) acrylic polymer is used as a base polymer, the cohesive force and durability are improved by crosslinking, which is preferable.
Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an oxazoline crosslinking agent, and a peroxide.
Diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diisocyanate adducts modified with various polyols, isocyanurate rings, burettes, and allophanates And a polyisocyanate compound in which is formed. In particular, aliphatic and alicyclic isocyanates are preferably used because the cross-linked product becomes transparent.
In addition, in an aqueous dispersion of a modified (meth) acrylic polymer produced by emulsion polymerization, an isocyanate crosslinking agent is often not used, but when used, the isocyanate group easily reacts with water. An isocyanate-based cross-linking agent may be used.

As the peroxide, any peroxide can be used as long as it generates radicals by heating to advance the crosslinking of the base polymer of the pressure-sensitive adhesive. For example, di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate, t-hexyl Peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di ( 4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexylperoxy) cyclohexane and the like. Among these, di (4-t-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, dibenzoyl peroxide, and the like are preferably used because of particularly excellent crosslinking reaction efficiency.
The peroxide may be used alone, or two or more kinds may be mixed and used, but the total content is 0.1% of the peroxide with respect to 100 parts by mass of the base polymer. It is preferable to contain 03-2 mass parts, it is more preferable to contain 0.04-1.5 mass parts, and it is still more preferable to contain 0.05-1 mass part. If the amount is less than 0.03 parts by mass, the cohesive force may be insufficient. On the other hand, if the amount exceeds 2 parts by mass, the crosslinking may be excessively formed and the adhesiveness may be poor.

  However, when an aromatic isocyanate compound is used as a cross-linking agent, the cured adhesive may be colored, so the application of the present invention requiring light transparency (light guide member) In this case, aliphatic or alicyclic isocyanates are preferably used.

  As a compounding quantity of the above crosslinking agents, although it changes also with kinds of (meth) acrylic-type polymer to be used, it is 0.03-2 mass parts normally with respect to 100 mass parts of (meth) acrylic-type polymers, Preferably Is used in the range of 0.05 to 1 part by mass. When the amount is too small, the cohesive force is insufficient, and when the amount is too large, the adhesiveness is lowered, which is not preferable.

Moreover, a silane coupling agent can be suitably added to an adhesive.
Examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3,4-epoxycyclohexyl). Epoxy group-containing silane coupling agents such as ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1, (3-dimethylbutylidene) propylamine, amino group-containing silane coupling agents such as N-phenyl-3-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane ( (Meth) acrylic group-containing Silane coupling agents, such as Inshianeto group-containing silane coupling agents such as 3-isocyanate propyl triethoxysilane and the like. Use of such a silane coupling agent is preferable for improving the durability of the pressure-sensitive adhesive. Moreover, the adhesiveness with respect to the glass base material of an adhesive is also improved.
The silane coupling agent may be used alone or in combination of two or more, but the total content is 100 parts by weight of the (meth) acrylic polymer. It is preferable to contain 0.01-2 mass parts of silane coupling agents, and it is more preferable to contain 0.02-1 mass parts. If the amount is less than 0.01 part by mass, the durability improving effect may be inferior. On the other hand, if the amount exceeds 2 parts by mass, the adhesive force may increase excessively and the removability may be inferior.

  The adhesive may contain an organic solvent in a very small amount, such as methanol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, cyclohexanol, benzyl alcohol, ethyl ether, 1,4-dioxane, Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, chloroform, toluene, m-xylene, p-xylene, o-xylene, n-hexane, cyclohexane, methyl acetate, ethyl acetate , Isopropyl acetate, propyl acetate, isobutyl acetate, butyl acetate, pentyl acetate (amyl acetate), isopentyl acetate, acetone, methyl ethyl ketone (MEK), cyclohexanone, , N- dimethylformamide (DMF), dimethylsulfoxide (DMSO) or the like is used is not particularly limited. These organic solvents are preferably contained in an amount of 0.001 to 1 part by weight, more preferably 0.001 to 0.5 parts by weight, and more preferably 0.001 to 0.005 parts per 100 parts by weight of the (meth) acrylic polymer. It is more preferable to contain 1 part by mass. If it is contained in an amount of more than 1 part by mass, the organic solvent generated from the pressure-sensitive adhesive may dissolve a substrate or a layer having a concavo-convex structure on the surface, which is not preferable. On the other hand, when it contains less than 0.001 part by mass, drying time and drying cost may be required.

  The pressure-sensitive adhesive may contain other known additives such as vulcanizing agents, tackifiers, colorants, pigments and other powders, dyes, surfactants, plasticizers, surface lubricants. Depending on the use of leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, foils, etc. Can be added as appropriate. Moreover, you may employ | adopt the redox type | system | group which added the reducing agent within the controllable range.

In addition, the adhesive can be prepared in the form of being laminated on the support that has been subjected to the peeling treatment when the light guide member is manufactured. For example, the pressure-sensitive adhesive can be coated, dried and cross-linked onto a release-treated support to obtain a sheet with a pressure-sensitive adhesive layer. Specifically, a pressure-sensitive adhesive is applied and dried on a release-treated support, and a release-treated film having a relatively low peel strength is bonded thereon to produce a sheet with a pressure-sensitive adhesive. Alternatively, the pressure-sensitive adhesive may be applied and dried on the support that has been subjected to the peeling treatment, and then immediately bonded to the substrate.
As such a support material, for example, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, acrylic resins such as polymethyl methacrylate, thermoplastic resins such as polycarbonate resin, polystyrene resin, polymethylpentene resin, Transparent base material composed of a resin obtained by curing an ionizing radiation curable resin composed of an oligomer such as polyester acrylate, urethane acrylate, epoxy acrylate and / or an acrylate monomer with electromagnetic radiation such as ultraviolet rays or electron beams, etc. However, polyethylene terephthalate is generally used from the viewpoint of economy. Moreover, as a peeling process, a silicone layer is apply | coated or an emboss shape is provided.
The pressure-sensitive adhesive is applied by any coating method such as reverse coater, comma coater, lip coater, die coater, etc., so that the thickness of the pressure-sensitive adhesive after drying is usually 2 to 500 μm, preferably 5 to 100 μm. Is done.

When the pressure-sensitive adhesive contains a crosslinking agent, the gel fraction of the pressure-sensitive adhesive after crosslinking is 30 to 90% by mass, preferably 40 to 90% by mass, more preferably after coating and drying on the release-treated support. May be crosslinked so as to be 45 to 85% by mass.
If the gel fraction is too small, the cohesive force is inferior, and if it is too large, it is not preferable because the adhesiveness is inferior. Even if the monomer is generated, the foaming phenomenon at the adhesive interface between the substrate and the pressure-sensitive adhesive can be suppressed. Here, the gel fraction of the pressure-sensitive adhesive refers to the ratio of the pressure-sensitive adhesive that does not dissolve in ethyl acetate, and is an index indicating the ratio (% by mass) of the crosslinked one.
(Measurement of gel fraction)
The gel fraction can be measured as follows.
W ₁ g of the pressure-sensitive adhesive was taken out and immersed in ethyl acetate at room temperature (about 25 ° C.) for 7 days. Then, the pressure-sensitive adhesive (insoluble matter) subjected to the immersion treatment was taken out from ethyl acetate, and the mass W ₂ g after drying at 130 ° C. for 2 hours was measured. Gel fraction is gel fraction (mass%) = (W ₂ / W ₁ ) × 100
As calculated.

The displacement of TMA (thermomechanical analysis) at 100 ° C. of the material constituting the adhesive layer is preferably in the range of −1 to 2 μm, more preferably 0 to 1 μm, still more preferably 0 to 0.5 μm. is there. If the displacement of the TMA is too small, peeling or the like after sticking is likely to occur, and if it is too large, undulation is caused by heat, which is not preferable.
(Measurement of thermal mechanical analysis (TMA) displacement)
Thermomechanical analysis was performed under the following conditions.
・ Device: Seiko Instruments TMA / SS120
-Probe: Needle-in probe (tip diameter: 1 mm)
・ Load: 10mN (1.02g)
・ Atmosphere: Air ・ Temperature range: 30 to 200 ° C
Temperature rising time: 5 ° C./minute Measurement sample: 25 μm-thick adhesive layer was cut into 5 mm square and attached to a quartz disk (10 mmφ).

The TG / DTA (weight reduction rate) at 100 ° C. of the material constituting the adhesive layer is preferably in the range of 0 to −0.4%, more preferably 0 to −0.3%, still more preferably. Is 0 to -0.2%. If the TGA is too large, the adhesive layer is deteriorated by heat, which is not preferable.
(Measurement of thermogravimetric analysis)
Thermogravimetric analysis was performed under the following conditions.
・ Device: TG / DTA220 manufactured by Seiko Instruments Inc.
・ Atmosphere: Nitrogen (Flow rate: 250ml / min)
-Temperature range: 30 ° C to 200 ° C
Temperature rising time: 10 ° C./min Sample preparation: An adhesive layer having a thickness of 25 μm was folded so that the total mass was 10 mg and set in a sample container.

The peel strength of the material constituting the adhesive layer is preferably in the range of 0.3 to 1.5 N / mm, more preferably 0.4 to 1.2 N / mm, still more preferably 0.5 to 1.N. 0 N / mm. If the peel strength is too low, peeling or the like after sticking is likely to occur.
(Measurement of peel strength)
The peel strength was measured under the following conditions.
Apparatus: RTG-1210 manufactured by A & D
・ Peeling angle: 90 °
・ Peeling speed: 50 mm / min
・ Measurement distance: 50mm
Test environment: temperature 23 ° C, humidity 50%
-Adhesive sample: After affixing an adhesive layer to a polyethylene terephthalate film (Toyobo Cosmo Shine A4300, 75 μm thickness), the width was cut to 3.5 mm, and an acrylic plate (Kanase Industries, Kanaselite 1300, thickness: 2 mm, size 25 cm × 3 cm) and left for 1 day in an environment of temperature 23 ° C. and humidity 50% was used as a measurement sample.

The refractive index of the material constituting the adhesive layer is preferably in the range of 1.40 to 1.70, more preferably 1.45 to 1.65, and still more preferably 1.45 to 1.60.
(Measurement of refractive index)
The refractive index was measured under the following conditions.
Under an atmosphere of 25 ° C., sodium D line (589 nm) was irradiated, and the refractive index was measured using an Abbe refractometer (manufactured by ATAGO, DR = M4).

  The thickness of the adhesive layer is not limited. For example, the adhesive layer may be adjusted so that the total light transmittance of the adhesive layer is 90% or more and the haze is 1.0 or less, but the thickness of the adhesive layer is 5 to 200 μm. It is preferable because peeling between the base material and the adhesive layer and between the adhesive layer and the layer having a concavo-convex structure on the surface is unlikely to occur. The thickness of the adhesive layer is more preferably 10 to 100 μm, further preferably 15 to 50 μm, and further preferably 20 to 30 μm. If the thickness of the adhesive layer is too thin, if the substrate has fine irregularities, the adhesive layer cannot follow the irregularities (cannot absorb the irregularities), increasing the probability of poor bonding. To do. On the other hand, if the thickness of the adhesive layer is too large, the area of the cross section becomes large, so that the probability of occurrence of problems such as sticking out of the adhesive and occurrence of lumps increases during the manufacture of the light guide plate. Further, if the thickness of the adhesive layer is too thick, there is also a disadvantage that the length that can be wound around the same roll diameter is shortened when the adhesive layer is handled in a roll shape in the manufacturing process.

  One or more fine grooves are formed on the surface of the adhesive layer on the side in contact with the base material so that air bubbles generated between the base material and the adhesive layer escape when the light guide plate is used under high temperature and high humidity. It may be formed. There is no limitation on the width, cross-sectional shape, depth, and the like of such a groove, but the width is preferably 0.5 mm or less, more preferably 0.3 to 0.01 mm. Moreover, the depth can be 0.5-0.01 mm, for example. The length of the groove is not limited, but it is preferable that the groove is crossed or vertically cut.

Next, a layer having a concavo-convex structure on the surface will be described.
Although the thickness of the layer having a concavo-convex structure on the surface is not limited, it is preferably about 25 to 500 μm from the viewpoint of adhesiveness with the adhesive layer. If it is too thin, the stiffness will be insufficient, and the workability at the time of pasting on the substrate will be reduced. On the other hand, if it is too thick, the stiffness will be too strong and the workability of pasting will be reduced. It is more preferable that

The layer having a concavo-convex structure on the surface may have a multilayer structure including a transparent base film layer and a resin layer having a plurality of concave portions or convex portions on the surface laminated thereon.
In this case, the material of the resin layer having a concavo-convex structure on the surface is not limited, and examples thereof include a cured product of a photopolymerizable resin composition.
The material and thickness of the transparent base film layer are not limited, and examples of the material include highly transparent materials such as polyethylene terephthalate, polycarbonate, and polystyrene (for example, the total light transmittance is 90% or more, and the haze is 1). 0.0 or less), and the thickness can be, for example, 20 to 250 μm, more preferably 50 to 125 μm.

  The photopolymerizable resin composition is the same as the resin layer of the diffusion sheet of the first invention of the present specification described later, that is, (A) an addition polymerizable monomer having at least one terminal ethylenically unsaturated group. It is preferable to use those containing 70 to 99.9% by mass and (B) a photopolymerization initiator: 0.1 to 30% by mass.

  (A) As an addition polymerizable monomer having at least one terminal ethylenically unsaturated group, for example, a compound represented by the following general formula (I) having a biphenyl group can be used.

Formula (I)

(In general formula (I), R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.)

The compound having the structure represented by the general formula (I) is a compound in which the substitution position of the biphenyl group is an ortho position or a para position, and X is a divalent organic group having 1 to 12 carbon atoms. Preferably, it is a compound represented by the following general formula (II).
In general formula (II), R represents a hydrogen atom or a methyl group, A independently represents an alkylene group having 1 to 4 carbon atoms, and n represents an integer of 1 to 3.

Formula (II)

In addition, as the addition polymerizable monomer (A) having at least one terminal ethylenically unsaturated group, in addition to the compound represented by the above general formula (I), a compound having a known (meth) acrylate group or allyl group Can also be used.
For example, nonylphenol acrylate, alkoxylation (1) o-phenylphenol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, β-hydroxypropyl-β ′-(acryloyloxy) propyl phthalate, 1,4-tetramethylene glycol di ( (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, octapropylene glycol di (meth) acrylate, glycerol (meth) acrylate, 2-di (p-hydroxy) Phenyl) propane di (meth) acrylate, glycerol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, polyoxypropyltrimethylolpropane tri (meth) acrylate Polyoxyethyltrimethylolpropane tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane triglycidyl ether tri (meth) acrylate, bisphenol A diglycidyl ether di (Meth) acrylate, diallyl phthalate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, bis (triethylene glycol methacrylate) nonapropylene glycol, bis (tetraethylene glycol methacrylate) polypropylene glycol, bis (triethylene glycol) Methacrylate) polypropylene glycol, bisarylfluorene derivatives, bis (diethyl) (Lene glycol acrylate) polypropylene glycol, compounds containing both ethylene oxide chain and propylene oxide chain in the molecule of bisphenol A (meth) acrylate monomer. Among these, alkoxylated (1) o-phenylphenol acrylate is preferable from the viewpoint of refractive index, and ethoxylated (1) o-phenylphenol acrylate (for example, product name A-LEN-10, manufactured by Shin-Nakamura Chemical Co., Ltd.) is particularly preferable. preferable.
A urethanized compound of a polyvalent isocyanate compound such as hexamethylene diisocyanate or tolylene diisocyanate and a hydroxy acrylate compound such as 2-hydroxypropyl (meth) acrylate can also be used.
The urethanized compound in this case is preferably less than 10,000 in terms of polystyrene-reduced number average molecular weight by gel permeation chromatography (GPC).
The above-mentioned (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group may be used alone or in combination of two or more.

The content of the (A) addition polymerizable monomer in the photopolymerizable resin composition is preferably 70% by mass or more and 99.9% by mass or less based on the total mass of the photopolymerizable resin composition, and more preferably. Is 75 mass% or more and 95 mass% or less. From the viewpoint of sufficient curing, it is preferably 70% by mass or more, but it is preferably 99.9% by mass or less in consideration of blending an initiator component, other polymerization inhibitor, dye, and the like.
Moreover, it is preferable that the content rate of the compound represented by the said general formula (I) is 50-95 mass%. From the viewpoint of increasing the refractive index of the resin layer, 50% by mass or more is preferable, and from the viewpoint of preventing a decrease in photocurability, the content is preferably 95% by mass or less.

Examples of the photopolymerization initiator (B) in the photopolymerizable resin composition include benzyl dimethyl ketal, benzyl diethyl ketal, benzyl dipropyl ketal, benzyl diphenyl ketal, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, Benzoin phenyl ether, thioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diisopropylthioxanthone, 2-fluorothioxanthone, 4-fluorothioxanthone, 2-chloro Thioxanthone, 4-chlorothioxanthone, 1-chloro-4-propoxythioxanthone, benzophenone, 4,4'-bis (dimethylamino) benzofe Aromatic ketones such as non [Michler's ketone], 4,4′-bis (diethylamino) benzophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one , Biimidazole compounds such as 2- (o-chlorophenyl) -4,5-diphenylimidazolyl dimer, acridines such as 9-phenylacridine, α, α-dimethoxy-α-morpholino-methylthiophenylacetophenone, 2,4 , 6-trimethylbenzoyldiphenylphosphine oxide, phenylglycine, N-phenylglycine, 1-phenyl-1,2-propanedione-2-O-benzoyloxime, ethyl 2,3-dioxo-3-phenylpropionate 2- (O-benzoylcarbonyl) -oxime Oxime esters such as p-dimethylaminobenzoic acid, p-diethylaminobenzoic acid, and p-diisopropylaminobenzoic acid, and esterified products thereof with these alcohols, p-hydroxybenzoic acid ester, 3-mercapto-1,2 Triazoles such as 1,4-triazole, tetrazoles, N-phenylglycine, N-phenyl-N-phenylglycine, N-phenylglycine such as N-ethyl-N-phenylglycine, and 1-phenyl-3- Styryl-5-phenyl-pyrazoline, 1- (4-tert-butyl-phenyl) -3-styryl-5-phenyl-pyrazoline, 1-phenyl-3- (4-tert-butyl-styryl) -5- (4 And pyrazolines such as -tert-butyl-phenyl) -pyrazoline.
Among these, 2-hydroxy-2-methyl-1-phenyl-propan-1-one (for example, product name DAROCURE 1173, manufactured by Ciba Specialty Chemical) is preferable.

The content of the photopolymerization initiator (B) in the photopolymerizable resin composition is preferably 0.1% by mass or more and 30% by mass or less based on the total mass of the photopolymerizable resin composition, and more preferably. Is 1 mass% or more and 20 mass% or less.
When the content of (B) is 0.1% by mass or more, sufficient photocuring sensitivity is obtained, and when it is 30% by mass or less, storage stability as a liquid resin before photocuring is obtained.

In order to improve thermal stability and storage stability, it is preferable to contain a radical polymerization inhibitor in the photopolymerizable resin composition.
Examples of such radical polymerization inhibitors include p-methoxyphenol, hydroquinone, pyrogallol, naphthylamine, t-butylcatechol, cuprous chloride, 2,6-di-t-butyl-p-cresol, 2,2 Examples include '-methylenebis (4-ethyl-6-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), and the like.
The content of the radical polymerization inhibitor is preferably 0.001% by mass or more and 1% by mass or less based on the total mass of the photopolymerizable resin composition.
The photopolymerization resin composition may contain an organic solvent in a small amount. For example, methanol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, cyclohexanol, benzyl alcohol, ethyl ether, 1, 4 -Dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, chloroform, toluene, m-xylene, p-xylene, o-xylene, n-hexane, cyclohexane, methyl acetate , Ethyl acetate, isopropyl acetate, propyl acetate, isobutyl acetate, butyl acetate, pentyl acetate (amyl acetate), isopentyl acetate, acetone, methyl ethyl ketone (MEK), cyclohexane Sanon, N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO) or the like is used is not particularly limited. These organic solvents are preferably contained in an amount of 0.001 to 1 part by mass, more preferably 0.001 to 0.5 part by mass, and even more preferably 0.001 to 0.1 part by mass. If it is contained in an amount of 1 part by mass or more, other materials in contact with the organic solvent generated from the photopolymerization resin composition may be dissolved, which is not preferable. When it contains less than 0.001 part by mass, it is not preferable because it takes a drying time and a drying cost.

The refractive index of the photopolymerizable resin composition after curing is preferably in the range of 1.40 to 1.70, more preferably 1.45 to 1.65, still more preferably 1.45 to 1.60. .
When the refractive index is lower than 1.40, when the light guide plate of the present invention is used as a surface light source device, the ability of the resin layer having a concavo-convex structure on the surface to uniform the luminance unevenness derived from the light source decreases. If the refractive index is higher than 1.70, the production becomes difficult.
(Measurement of refractive index)
The refractive index was measured under the following conditions.
Under an atmosphere of 25 ° C., sodium D line (589 nm) was irradiated, and the refractive index was measured using an Abbe refractometer (manufactured by ATAGO, DR = M4).

As for the thickness of the resin layer having a concavo-convex structure on the surface, the concavo-convex structure cannot be formed if it is too thin. There is also a possibility that discoloration when left for a long time exceeds the allowable range. From such a viewpoint, the thickness can be set to 2 to 50 μm.
In addition, in order to improve optical performance, the resin layer having an uneven structure on the surface can be mixed with, for example, silicon fine particles having an average particle diameter of about 2 μm to give internal diffusion performance. In the embodiment, an ultraviolet curable resin having no such internal diffusion performance is used.

  In the light guide plate of the present invention, there may be at least one light incident surface, and there may be two or more. When two light incident surfaces are provided, the shape of the light guide plate is preferably a flat rectangular parallelepiped having a light exit surface and an opposite surface as a main surface, and the two light incident surfaces are preferably opposed to each other. In this case, since two opposing light incident surfaces have the same length, there is a merit that the number and type of point light sources can be made the same and parts can be shared.

  Although there is no limitation on the thickness of the light guide plate (the distance between the light exit surface and the facing surface facing this), it can be, for example, about 2.0 to 5.0 mm.

  The material of the light guide plate of the present invention is not particularly limited as long as it is translucent. For example, it is generally used as a material for optical parts such as polymethyl methacrylate, polycarbonate, polystyrene, and methyl methacrylate-styrene copolymer. A highly transparent polymer material or an inorganic material such as glass can be used.

  In addition, the light guide plate of the present invention includes organic and inorganic dyes and pigments, matting agents, heat stabilizers, flame retardants, antistatic agents, antifoaming agents, color stabilizers, antioxidants, UV absorption as necessary. An additive such as an agent, an impurity scavenger, a thickener, a surface conditioner, and a release agent may be contained within a range not impairing the object of the present invention.

  The concavo-convex structure (plurality of concave portions or convex portions) in the light guide plate of the present invention has an anisotropic shape in which the openings (bottom surfaces) of the plural concave portions (convex portions) are long in a specific direction. Depending on the surface shape, the diffusion angle in the direction perpendicular to the specific one direction (that is, the major axis direction of the opening (bottom surface) of the concave portion (convex portion)) is the maximum, and the direction parallel to the specific one direction An anisotropic diffusion characteristic with a minimum diffusion angle is shown.

The specific value of the diffusion angle (the diffusion angle (FWHM) of the emitted light when a light beam is incident on the light incident surface perpendicularly) is not limited, but the direction perpendicular to the specific one direction (parallel to the light output surface). The diffusion angle in the right direction) is preferably 30 ° or more, more preferably 40 ° or more, still more preferably 50 ° or more, and particularly preferably 65 ° or more. Moreover, it is preferable that the upper limit is 120 degrees or less, 100 degrees or less may be sufficient, and 90 degrees or less may be sufficient.
On the other hand, the diffusion angle in the one specific direction (direction perpendicular to the light exit surface) is recommended to be 10 ° or less, preferably 5 ° or less, more preferably 1 ° or less, Most preferably 0.5 ° or less.

  The ratio of the maximum value to the minimum value of the diffusion angle is preferably 200 or more, and more preferably 400 or more. By making the ratio of the maximum value to the minimum value of the diffusion angle in such a range, luminance unevenness can be further reduced. Note that the ratio of the maximum value to the minimum value of the diffusion angle will be described in detail in the description related to the third invention of the specification to be described later.

  Both the diffusion angle in the direction perpendicular to the specific direction and the direction parallel to the specific direction can be adjusted by appropriately changing the shape, depth (height), pitch, and the like of each recess (projection). When the groove structure is formed using the speckle pattern, these can be adjusted by appropriately changing the conditions for diffusing the laser beam.

  Except in the case of the second invention described below, the diffusion characteristics are preferably substantially constant over the entire region where the concavo-convex structure is formed.

Here, the “diffusion angle” refers to an angle (FWHM: Full Width Half Maximum) that is twice the angle (half-value angle) at which the transmitted light intensity attenuates to half of the peak intensity (see FIG. 8). This diffusion angle can be measured by, for example, Photon Inc. Transmission of light incident on the concavo-convex structure from the normal direction of the surface on which the concavo-convex structure is formed, using a variable angle color difference meter such as Photon or Beam Profiler NanoScan made by Nippon Denshoku Industries Co., Ltd. It can be obtained by measuring the angular distribution of light intensity (distribution of the intensity of transmitted light with respect to the emission angle). In particular, NanoScan is most suitable for measurement with respect to the characteristics with FWHM of 1 ° or less. Here, the normal direction of the surface on which the concavo-convex structure is formed refers to the direction indicated by 16 in FIG.
In addition, the definition of the diffusion angle is that the angle distribution of transmitted light intensity has a maximum peak near 0 degrees,
The definition is based on the assumption that the peak decreases monotonously on both sides of the maximum peak.
In the case where (1) the maximum peak is other than the center, or (2) peaky transmission intensity exists at a specific angle, that is, there is a peak whose maximum peak width (root width) is 10 ° or less. In light of the purpose of the main body that defines the diffusion angle, (1) the half-value width of the transmitted light intensity value near 0 degrees is applied, and (2) the transmission intensity obtained by taking a moving average in the range of ± 15 °. The full width at half maximum will be applied.

Note that the diffusion angle is theoretically (Snell's law), and if the substrate does not have internal diffusion performance, it is not affected by the refractive index of the substrate and is a material that forms the surface on which the concavo-convex structure is formed. Depends on refractive index. For this reason, if the manufacturing method of (3) above is adopted as a method for forming the concavo-convex structure on the light incident surface of the light guide plate, even if the diffusion angle is measured with the film having the concavo-convex structure alone, this is used as the light guide plate. Even if the diffusion angle is measured in the state of the final form bonded together, the measurement result does not change.
Further, if the production methods (1) and (2) are adopted, a thin piece cut by a plane parallel to the light incident surface may be produced and the diffusion angle thereof may be measured.

  In addition, when the surface facing the surface to be measured is not smooth, the surface is made smooth by cutting or the like, or the surface shape of the surface to be measured is the same refraction as the material forming the surface It can be measured by transferring to a material having a rate and using this (even if the irregularities are inverted, the angular distribution of transmitted light intensity incident from the 0 degree direction does not change, and thus the diffusion angle does not change).

  Further, when a light beam is incident on the light incident surface on which the concavo-convex structure is formed from the normal direction, the transmitted light intensity of the light is preferably 90% or more of the peak intensity at the emission angle = 0 °. .

Specific examples are shown in FIGS. 15A and 15B. FIGS. 15A and 15B are angular distributions of transmitted light intensity of a film having a concavo-convex structure alone, measured using a GC5000L manufactured by Nippon Denshoku Industries Co., Ltd.
The transmitted light intensity in the ◇ (outlined) portion in the figure is 90% or more of the peak intensity. In either angular distribution, the transmitted light intensity is 90% or more of the peak intensity at the emission angle = 0 °.
As described above, the surface shape of the light incident surface on which the concavo-convex structure is formed is such that the angular distribution of the transmitted light intensity of light when a light beam is incident from the normal direction does not have a plurality of peaks and changes gently. It is preferable that it is such.

  In the light guide plate of the present invention, it is presumed that the effect of reducing luminance unevenness such as hot spots is improved by the anisotropic diffusion characteristics derived from the surface shape of the plurality of concave portions or convex portions as described above.

  The anisotropic diffusion characteristic is also used in the technique disclosed in Patent Document 5, but it is difficult to obtain highly accurate anisotropy by the method of dispersing the filler. The diffusion angle in the direction cannot be maximized. When such a member having low accuracy of anisotropy is provided on the light incident surface, the light guide efficiency is deteriorated. Furthermore, light leakage immediately after entering the light guide plate becomes severe due to insufficient anisotropy, and quality suitable for display devices and surface light source devices cannot be obtained. In addition, in the technique disclosed in Patent Document 5, anisotropy is imparted using refraction between the pressure-sensitive adhesive and the filler. Since the difference in refractive index between the two is small, the light guide plate moves in one direction. The diffusion angle cannot be made sufficiently large.

  In contrast, in the light guide plate of the present invention, anisotropic diffusion characteristics are realized by the surface shape of the concavo-convex structure. By controlling the surface shape, highly accurate anisotropic diffusion characteristics can be stabilized. Can get to. Furthermore, in the present invention that realizes anisotropic diffusion characteristics by the surface shape, refraction that causes anisotropic diffusion is a material (resin or resin composition) that forms an uneven structure with air (refractive index of approximately 1) ( The refractive index is about 1.3 to 1.6), and compared with the technique disclosed in Patent Document 5 that utilizes the refraction between the adhesive and the filler, the opening of the recess (convex) The diffusion angle in the direction perpendicular to the major axis direction of the (bottom surface) can be set to a large value.

When the light incident surface of the light guide plate of the present invention further satisfies the following requirements, the luminance unevenness is further reduced.
The entire light incident surface has anisotropic light diffusion characteristics in which the diffusion angle of incident light from the normal direction in the longitudinal direction of the incident surface is greater than the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface. ,
The light emission pattern curve of the entire light incident surface with the horizontal axis representing the emission angle of the light emitted from the normal direction of the light incident surface in the longitudinal direction of the light incident surface and the vertical axis representing the intensity appears in the light emission pattern curve. When compared with a normal distribution curve passing through a total of three points: one peak point where the intensity of the emitted light is the peak intensity and two intermediate points where the intensity of the emitted light is half of the peak intensity, the following conditions 1. And / or condition 2. Meet.
Condition 1. The range of the emission angle where the intensity of the emitted light is 3/4 or more of the peak intensity is narrower than the normal distribution curve.
Condition 2. The range of the emission angle where the intensity of the emitted light is 1/10 or more of the peak intensity is wider than the normal distribution curve.
Such a requirement will be described in detail in the description related to the second invention of the specification below.

Next, the light output surface and the opposing surface of the light guide plate of the present invention will be described.
A groove structure substantially parallel to the normal direction of the light incident surface can be provided on the light exit surface and / or the opposite surface of the light guide plate of the present invention. Providing such a groove structure on the light exit surface can improve the straightness that suppresses the spread of the light emitted from the light exit surface, so that the light guide plate can be suitable for local dimming.
The groove structure is preferably a lenticular lens shape or a plurality of random grooves. Whether the groove structure is provided on the light exit surface or the facing surface may be appropriately determined in consideration of ease of manufacture, ease of handling, and the like. Although it may be provided on both the light exit surface and the facing surface, for example, when the light scattering processing described later is provided on the facing surface, it is preferably provided only on the light exiting surface.
Furthermore, from the viewpoint of reducing hot spots in the area near the light incident surface, the groove structure starts from a position 1 to 50 mm inside from the light incident surface side end of the light exit surface and / or the opposite surface. It is preferable to provide it so that it may extend in the opposite direction.

  The lenticular lens shape preferably extends in a direction substantially parallel to the normal direction of the light incident surface and is provided in parallel. The pitch of the lenticular lens shape is preferably 20 to 500 μm, and the depth is preferably 20 to 500 μm (see FIG. G19). If the pitch is too small, accurate processing of the lenticular lens is difficult, and if the pitch is too large, moire between the pixels of the liquid crystal panel is likely to occur. If the depth is too shallow, the straightness of light decreases, and if the depth is too deep, accurate machining becomes difficult or easily damaged.

Next, a plurality of random grooves will be described.
That the plurality of grooves are random means that at least one of the cross-sectional shape, pitch, and depth of the plurality of grooves is randomly (irregularly) different.
FIG. G19 shows an example in which a plurality of random grooves substantially parallel to the normal direction of the light incident surface are provided on the light exit surface.

There is no limitation in the cross-sectional shape of each groove | channel, For example, it can be set as V shape or U shape.
The pitch of the grooves refers to a horizontal distance between the valley bottoms of adjacent grooves (a horizontal distance in a direction parallel to a surface having a plurality of random grooves). When the valley bottom is flat, the pitch is determined with the center as the valley bottom. The cross-sectional shape and width of the groove may change along the extending direction of the groove.
The depth of the groove is the vertical distance between the peak of the higher peak of the peaks on both sides of each groove and the valley bottom of the groove (distance in the direction perpendicular to the surface having a plurality of random grooves). (Elevation difference between mountain top and valley bottom).
The depth of the groove may change gently or steeply along the extending direction, and as a result, there may be a portion where the groove is interrupted, but it is preferable that it does not change if possible.
Specific examples of a plurality of random grooves that can be preferably used in the present invention are shown in FIGS. G21A and G21B. FIG. G21A shows a specific example of a plurality of random grooves having anisotropic light diffusion characteristics in which the diffusion angle in the direction perpendicular to the groove (described later) is 30 degrees and the diffusion angle in the direction horizontal to the groove is 1 degree. FIG. G21B is a surface showing a specific example of a plurality of random grooves having anisotropic light diffusion characteristics in which the diffusion angle in the direction perpendicular to the grooves is 60 degrees and the diffusion angle in the direction horizontal to the grooves is 1 degree. It is a profile figure.

The average pitch of a plurality of random grooves is not limited, but is preferably 30 μm or less, more preferably 20 μm or less, still more preferably 15 μm or less, and particularly preferably 10 μm or less. The average pitch of the plurality of random grooves is preferably 580 nm (the central wavelength of visible light) or more, more preferably 780 nm (the entire visible light region) or more.
Since the pixel pitch of the display panel used in combination with the light guide plate and the structure pitch of the optical sheet are approximately 100 to 600 μm and 50 to 150 μm, respectively, the average pitch of a plurality of random grooves is set to such a value. If set, generation of moire due to spatial interference with a display panel or an optical sheet used in combination with the light guide plate can be prevented. Furthermore, if the average pitch is set to such a value, the claw and the like are not easily caught in the groove during handling, and handling is improved. Furthermore, since the light guided by the light guide plate of the present invention is visible light (an electromagnetic wave of 380 nm to 780 nm), in order to sufficiently exhibit the effect of direct evolution of light by a plurality of random grooves, the average pitch is The lower limit is preferably a value as described above.
The average depth of the plurality of random grooves is not limited, but is preferably 1 to 50 μm, more preferably 5 to 10 μm.

The slope angle of the groove has a great influence on the straightness of light. In other words, when a groove structure is provided on the light exit surface or the opposite surface, light that spreads outward in the light guide plate is reflected by the slope of the groove and returned to the light guide plate, thereby improving the straightness of the light. It is done. Therefore, the slope angle of each groove is preferably 40 to 60 degrees. Accordingly, it is preferable that the proportion of the plurality of random grooves provided on the light exit surface or the opposing surface is within a range of 40 degrees to 60 degrees of the slope angle of the grooves is 5% or more. More preferably, it is 10% or more. Of these, the greater the proportion occupied by 45 ± 5 degrees contributes to the improvement in straightness.
Here, the “slope angle” is a general term for an angle formed by a surface tangent to each groove and a surface having a groove structure in a cross section perpendicular to the groove of a surface having a plurality of random grooves.
And about the ratio which a slope angle has in the range of 40 degree-60 degree | times, the arbitrary perpendicular | vertical of the surface which has a random several groove | channel by microscope observation (a scanning electron microscope, a laser confocal microscope, etc.) A range with a distance of 300 μm is extracted arbitrarily from the cross section (cross section perpendicular to the groove structure), and tangents with points at 0.5 μm points from the end of the range are extracted. It is determined by measuring an angle (acute angle) formed by the surface having the groove.

In addition, a light scattering process having a gradation toward the direction away from the light incident surface may be formed on the opposite surface of the light guide plate of the present invention in order to make the light distribution on the light output surface uniform. In addition, in a display device, it is preferable that a uniform mountain-shaped light distribution with the highest luminance at the center of the screen is easily visible while improving the uniformity of the light distribution.
As light scattering processing, for example, a dot or uneven shape is made into a gradation pattern in which the area gradually increases as it moves away from the light incident surface, or the same size dot or uneven shape becomes narrower as it moves away from the light source. A gradation pattern that can be used. In this case, examples of the shape of the dots and irregularities include a circle and a quadrangle, and the size can be, for example, about 0.1 to 2.0 mm.

The light guide plate having a concavo-convex structure on the light incident surface as in the present invention is slightly different from that in which the light incident surface is smooth in the direction perpendicular to the light incident surface (light propagation direction). In other words, the amount of light emitted from the light exit surface in the region close to the light entrance surface is larger than that of the light guide plate having a smooth light entrance surface, while the amount of light emitted from the light exit surface in the region far from the light entrance surface is incident. The light surface tends to be smaller than that of a light guide plate having a smooth surface. Therefore, compared to a light guide plate having a smooth light incident surface, the partial light scattering pattern close to the light incident surface of the reflective surface has a shape that is more difficult to scatter than conventional ones (for example, the area of dots and uneven shapes has been further reduced) Or the density is preferably sparse.
However, when the change in the light propagation direction of the amount of light emitted from the light exit surface is too large, there is a limit in the correspondence with the pattern having gradation (for example, when the area is changed, the area is 0% or more and 100% or less). Can only be changed to a range).

FIG. D16 shows the brightness of the light exit surface with the distance from the light entrance surface (light propagation direction, the direction of arrow 16 in FIG. 1) on the X axis and the brightness on the Y axis. However, this is the light incident surface of the light guide plate. In the region from the light incident surface to the inside of 16.5 mm, since the light-shielding plate is fixed to fix the distance between the light guide plate and the light source, the luminance is zero. A light guide plate having a smooth light entrance surface (reference), a light guide plate of the present invention (Production Example D-20), and a general diffusion sheet pasted on the light entrance surface of the light guide plate Comparing the luminance of (Production Example D-37), the brightness of Production Examples D-20 and D-37 is higher near the light incident surface than that of the reference, and the production example is farther from the light incident surface. The brightness of D-20 and D-37 is low.
In the light guide plate of the present invention, the brightness at each position on the light exit surface is preferably in the range of 50% or more and 150% or less as compared to the value when the light entrance surface is smooth. More preferably, they are 60% or more and 140% or less, More preferably, they are 70% or more and 130% or less.
Compared with the value when the light incident surface is smooth, the light scattering pattern on the reflective surface can be easily redesigned within this range.

Alternatively, in the light guide plate of the present invention, the light exiting surface and / or the opposing surface is provided near the light incident surface of the light shielding portion shielded by the frame (surface light source device) and / or the light shielding frame (TV receiver device). In the region B, it is possible to provide a light scattering process configured such that the light scattering degree of the partial region directly facing the light source is lower than the light scattering degree of the partial region directly facing the portion between the light sources.
In the region B in the vicinity of the light incident surface of the light shielding portion, a light scattering process is provided so that the light scattering degree of the partial region facing the light source is lower than the light scattering degree of the partial region facing the light source. Thus, in combination with the concavo-convex structure provided on the light incident surface (the light scattering process provided in the vicinity of the light incident surface of such a light exit surface and / or its opposite surface and the concavo-convex structure provided on the light incident surface. Complementing portions where the luminance unevenness reduction effect is mutually lacking), the uniformity of the luminance of the light exit surface is dramatically improved, and the P / G described later can be increased.
The “partial region directly facing the point light source (or the portion between the point light source and the point light source)” refers to the direction parallel to the light incident surface of the light exit surface as the X axis and the direction perpendicular to the light incident surface as the Y axis. Is a partial area having substantially the same X coordinate as the point light source (or the part between the point light source and the point light source), and “the light scattering degree of the partial area directly facing the point light source is the point light source and the point light source. "A lower than (or substantially equal to) the light scattering degree of the partial region directly facing the portion between" means that the partial region directly facing the point light source (substantially the light source) is compared when the partial regions having the same Y coordinate are compared. (Partial region having the same X coordinate) The light scattering degree of the partial region directly facing the portion between the point light source and the point light source (partial region having substantially the same X coordinate as the portion between the point light source and the point light source) It is lower (or approximately equal) than the degree of scattering.

  In the light shielding part shielded by the frame (surface light source device) or the light shielding frame (television receiving device) on the light exit surface and / or the opposing surface, the light scattering degree of the partial area directly facing the point light source is between the point light source and the point light source. A region B in the vicinity of the light incident surface on which light scattering processing is performed so as to be lower than the light scattering degree of the partial region directly facing the portion is a band-like area parallel to the light incident surface in the light shielding portion. However, it is not always necessary to start from the light incident surface side end (Y = 0).

  As a specific aspect of the configuration in which “the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing the portion between the point light source”, for example, a . Light scattering processing is performed in a region other than the partial region directly facing the point light source (light scattering processing is performed on the partial region directly facing the portion between the point light source and the point light source), b. Light scattering processing is applied to almost the entire area near the light incident surface, and the degree of light scattering is lower in the partial areas facing the point light source than in the other partial areas (the area between the point light source and the point light source is positive). For the partial area, the degree of light scattering is higher than that of the other partial areas).

  There is no limitation in light scattering processing, and those generally employed in the field of optical materials can be used. For example, a plurality of diffusive dot patterns made of a reflective or diffusive material may be provided by stacking or printing, or a plurality of three-dimensional dot patterns such as concavo-convex shapes may be formed. There is no limitation in the shape of a dot, For example, circular, a square, etc. are mentioned, The magnitude | size can be about 0.1-2.0 mm, for example.

  The light scattering degree is, for example, the concentration of a reflective (diffusible) substance in a diffusive dot made of a reflective (diffusive) material (the higher the density, the higher the light scattering degree), and the shape of the uneven three-dimensional dot. (For example, the higher the height, the higher the light scattering degree), and the ratio of the area of the dot-formed portion (hereinafter referred to as “dot density.” In this case, the dot density in the region is surrounded by vertical bisectors 26a to 26f connecting the center of the dot 26 and the centers of the adjacent dots A to F as shown in FIG. It can be controlled by adjusting the ratio (%) of the area of the dot 26 to the area of the square 262, and the higher the dot density, the higher the light scattering degree. Dot density, for example, changes the area of each dot with a constant number of dots per unit area, or conversely changes the number of dots per unit area with a constant area of each dot (dot pitch) It is possible to make adjustments by changing both of them.

In the present invention, a region A (at least a non-light-shielding portion) that covers at least a non-light-shielding portion that is not shielded by the frame (surface light source device) or the light-shielding frame (television receiver) on the light exit surface and / or the opposing surface of the light guide plate. Light-scattering processing can also be performed. At this time, the range of the region A is preferably set as appropriate so that a region C described later exists between the region A and the region B.
In the region A, at least in the non-light-shielding part, the light scattering degree of the partial area directly facing the point light source and the light scattering degree of the partial area directly facing the part between the point light source and the point light source are substantially equal. It is preferable.

The region C sandwiched between the region A and the region B is preferably a band-like region parallel to the light incident surface, in which case the width of the region C is preferably 0.2 mm or more, more preferably 0.5 mm or more. And most preferably 1 mm or more. Further, the upper limit of the width of the region C is preferably 3.0 mm or less, more preferably 2.0 mm or less, and most preferably 1.5 mm or less.
In the region C, it is preferable that light scattering processing is not provided at least in a partial region directly facing the portion between the point light source and the light source processing may not be provided at all in the region C. .

  18 and 19 show specific examples of the light scattering processing applied to the light exit surface and / or the facing surface. Further, in the example of FIG. 18, in the region B near the light incident surface, the light scattering process is not provided in the partial region directly facing the point light source, thereby facing the point light source in the region near the light incident surface. The light scattering degree of the partial area is set to be lower than the light scattering degree of the partial area directly facing the portion between the point light source and the point light source. In the example of FIG. 19, in the region B near the light incident surface, the area of each dot in the partial region facing the point light source is small, and in the portion between the point light source and the point light source near the light incident surface. By increasing the area of each dot of the facing partial area, the light scattering degree of the partial area directly facing the point light source in the area near the light incident surface is the light of the partial area facing the part between the point light source and the point light source. It is set to be lower than the scattering degree.

  FIG. 27 shows a cross-sectional view of an example of the surface light source device and the television receiver of the present invention. The light emitting area of the surface light source device is defined (restricted) by a frame (BL frame), and the display area of the television receiving device is defined (restricted) by a light shielding frame (black matrix).

FIG. 28 shows another specific example of the light scattering processing of the light exit surface and / or the opposing surface in the present invention.
In the example of FIG. 28, a partial area directly facing the point light source is located in a region B (a strip-shaped area parallel to the light incident surface) in the vicinity of the light incident surface in the light shielding portion (that is, outside the display area or the light emitting area). Light scattering processing is applied so that the light scattering degree is lower than the light scattering degree of the partial area directly facing the part between the point light source and the light scattering of the partial area directly facing the point light source. In the light scattering processing that is configured so that the degree of light scattering is lower than the light scattering degree of the partial region that directly faces the portion between the point light source and each of the partial regions that face the point light source in the region near the light incident surface By reducing the area of the dots, and by increasing the area of each dot in the partial area facing the part between the point light source and the point light source in the area near the light incident surface, the point light source in the area near the light incident surface Light scattering degree of the partial region facing directly It is set to be lower than the degree of light scattering of directly opposite partial region a portion between the point light source and a point light source.
In the non-light-shielding part (that is, the display area or the light emitting area), the light scattering degree of the partial area directly facing the point light source is substantially equal to the light scattering degree of the partial area directly facing the part between the point light source and the point light source. Is light-scattered. Specifically, when the light scattering degree is controlled by the dot density, the dot density ρ1 in the lowest dot density region and the highest dot density among the regions having the same distance from the light incident surface (regions having the same Y coordinate). The ratio (ρ2 / ρ1) of the dot density ρ2 in the high region is preferably ρ2 / ρ1 ≦ 1.2, more preferably ρ2 / ρ1 ≦ 1.1, and ρ2 / ρ1 = 1. Is most preferred.
A light scattering process configured such that the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing the part between the point light source and the light shielding part / non-light shielding part; The light scattering degree of the partial area directly facing the point light source is configured to be lower than the light scattering degree of the partial area directly facing the part between the point light source and the point light source. By placing the light scattering process in the light shielding portion), it is possible to prevent the luminance unevenness of the light emitting surface / display surface from being viewed not only from the front but also from an oblique direction.

FIG. 29 shows another specific example of the light scattering processing of the light exit surface and / or the opposing surface in the present invention.
In the example of FIG. 29, a region B (light incident surface) in the vicinity of the light incident surface that is set about several millimeters outside (light incident surface side) from the boundary with the non-light-shielded portion (display area or light emitting area) in the light shield portion. In a strip-like area parallel to the point light source), dots are formed at a density that is twice to 20 times higher than the dot density of the non-light-shielding part only in the partial region directly facing the part between the point light source and the point light source. The density is preferably 5 to 15 times, and most preferably about 10 times.
In this way, by performing light scattering processing only on the partial region directly facing the portion between the point light source and the point light source in the region B in the vicinity of the light incident surface of the light-shielding portion, a pseudo between the point light source and the point light source is obtained. By generating a light source and overlapping this with an image of an actual light source, it is possible to reduce luminance unevenness derived from a point light source.
Further, in the example of FIG. 29, the light scattering degree and the point light source of the partial area directly facing the point light source in the non-light-shielding part and the surrounding area (boundary area in the vicinity of the boundary between the light-shielding part and the non-light-shielding part). The region A is formed by performing light scattering processing so that the light scattering degree of the partial region facing the portion between the point light source and the point light source becomes substantially equal.
And between the area | region A and the area | region B, the area | region C (band-like area | region parallel to a light-incidence surface) in which the light-scattering process is not provided exists.

The region B preferably starts from the outside of 1 mm or more from the boundary between the light shielding part and the non-light shielding part. By doing so, the above-described pseudo light source can be prevented from being visually recognized by the user when the surface light source device or the television receiver is used.
In addition, the light scattering processing (light scattering processing to be a pseudo light source) applied to the partial region facing the portion between the point light source and the point light source in the region B near the light incident surface is the center (light source and light source). It is preferable to apply a gradation in which the degree of light scattering increases toward the middle). By doing so, the light reaching from the left and right point light sources is strongly scattered toward the central part in the partial area facing the part between the point light source and the point light source, and a dark part is generated in the center of the pseudo light source scattering processing part. It is possible to provide a natural pseudo light source unit. In addition, the density distribution of the gradation is normal to the point light source with respect to the partial region (the central region in the direction parallel to the light-scattering light incident surface that becomes a pseudo light source) that is directly opposite the point light source. The density in the vicinity of the corresponding partial area (both ends in the direction parallel to the light incident surface of the light scattering process as a pseudo light source) is preferably a gradation set in a range of about 5% to 80%, preferably 10% -70% is more suitable, 20%-50% is still more suitable, and 30%-40% is the most suitable.

When the light scattering degree is controlled by the dot density, the dot density ρ1 of the lowest dot density among the partial areas directly facing the point light source in the area B near the light incident surface and the point light source in the area B near the light incident surface The dot density so that the ratio (ρ2 / ρ1) of the dot density ρ2 of the region having the highest dot density among the partial regions directly facing the portion between the point light sources satisfies the following relationship: It is preferable to adjust ρ1 and ρ2.
2.9 ≦ 1.4 × (P / G) −ρ2 / ρ1 ≦ 3.1
Here, the dot density ρ (%) of a certain area is a specific dot (26) included in the area.
) And a perpendicular bisector (26a-f) of a line segment connecting the center point of the dot (A to F) adjacent to the specific dot so as to surround the specific dot The area ratio of the polygon (263) that can be formed as the denominator and the area ratio of the specific dot (26) as the numerator is expressed in% (see FIG. 26).

FIGS. A1 to 10 show still another specific example of the light scattering process applied to the light exit surface and / or the facing surface.
Further, in the table below, these light scattering processing and the light scattering processing of FIG. 33 employed in Production Example A-11 described later, and the optical sheet (diffusion sheet (DS)) laminated on the LED array pitch and the light guide plate , A preferred combination of prism sheet (Prism) and reflective polarizing sheet (DBEF).
In addition, when there is no description in the table | surface, it is normal to the light-incidence surface (a several recessed part (convex part) which has an anisotropic shape with an opening (bottom surface) long in a direction perpendicular | vertical to an output surface) of a light-guide plate. When a light beam is incident from the direction, the diffusion angle in a direction parallel to the light exit surface (in the table, indicated as “surface direction”) is preferably 50 ° to 100 °, and preferably 60 ° to 85 °. More preferably, it is 70 ° or more and 80 ° or less.
In addition, unless otherwise specified in the table, the normal to the light incident surface of the light guide plate (a plurality of concave portions (convex portions) having an opening (bottom surface) having a long anisotropic shape in a direction perpendicular to the light output surface) When a light beam is incident from the direction, the diffusion angle in the direction perpendicular to the light exit surface (in the table, “displayed as the thickness direction”) is preferably 20 ° or less, more preferably 1 ° or less. 0.5 ° or less is most preferable.

The effect of the pseudo light source between the light sources formed by the light scattering processing shown in FIG. A9 will be described.
The light scattering process of FIG. A9 is performed on the opposing surface of the light guide plate (material: polymethyl methacrylate, thickness: 3.0 mm, width: 409 mm, length: 721 mm), and is composed of diffusion beads and a binder. Circular diffusive dots with a diameter of 0.8 mm to 1.3 mm are arranged in a staggered pattern (in a triangular lattice pattern), 2.5 to 3.5 mm from the light incident surface side end (light-shielding portion, region near the light incident surface) In the partial area directly facing between the light sources of B), 4.5 to 6 mm from the end on the light incident surface side (shielding part (boundary area), area A) so that ρ = 50 to 100%. In FIG. 5, ρ = 10% is provided so that ρ = 9% after 6 mm from the light incident surface side end portion (non-light-shielding portion, region A), and in other regions. Are not provided with diffusive dots.
A polyethylene terephthalate film having an average thickness of 125 μm and having a groove structure having the surface profile shown in FIG. 24C is pasted on the light incident surface of the light guide plate subjected to light scattering processing in FIG. The LEDs (light emitting surface size 5.0 mm (width direction) × 3.0 mm (thickness direction), 42 LEDs) were arranged so that the array pitch P was 16.0 mm along the light incident surface.
On top of this, from the light guide plate side, a diffusion sheet (DS) / prism sheet (having a groove structure having a ridge line parallel to the light incident surface on which the LED is arranged on the surface) / DBEF are laminated in this order, Furthermore, a surface light source device is manufactured by disposing a frame having an opening of 395 mm × 700 mm in a size that sufficiently covers the light guide plate and the LED so as to face the light exit surface side of the light guide plate. When evaluated, the area of the pseudo light source formed between the light sources by light scattering processing is 2.5 to 3.5 mm even in the range of 1.5 to 2.5 mm from the light incident surface side end. Compared with the light guide plate in which the diffusive dots were formed with the density ρ similar to that in the range, the hot spot was suppressed more effectively, that is, it worked more strongly as a pseudo light source.
This indicates that the light scattering processing at the light incident surface side end 1.5 mm to 2.5 mm does not contribute much to the suppression of hot spots, and rather the light incident surface side end 2.5 mm to 3.5 mm. This suggests that reducing the amount of light that arrives reduces the effect of a pseudo-light source.
Also in the light scattering processing shown in FIGS. A2 to A8 and FIG. 33, the light incident surface edge portion is between 2.5 mm to 3.5 mm (corresponding to one line of dot lines in the size of diffusive dots applied thereto) The above-described effect can be obtained by replacing only the pattern of the part with the pattern between 2.5 mm and 3.5 mm in FIG.
In this case, since the dot lines are as simple as one line, the design is relatively easy and the development speed is improved. And it is also preferable to respond | correspond by forming only this dot 1 line part by the additional printing of another process, or bonding an additional dot seal to a back surface.

In order to achieve further uniformity of the light distribution on the light exit surface, the light scattering processing in the region near the light entrance surface and the light scattering processing in other regions are further performed in a direction away from the light entrance surface. A gradation that increases the degree of scattering (for example, a gradation in which the dot area increases as the distance from the light incident surface increases, or a gradation in which the pitch of the same size dot decreases as the distance from the light source decreases) can also be provided. .
Further, in the case of a surface light source device for a display device, it is preferable that a uniform mountain-shaped light distribution with the highest luminance at the center of the screen is easy to visually recognize while improving the uniformity of the light output distribution. The light scattering processing provided on the light exit surface and / or the opposing surface may be further configured to increase the light scattering degree of the central portion.

The light scattering process in the vicinity of the light incident surface described above may be provided on either the light exit surface or the opposing surface, or may be provided on both. However, when the light scattering process is easily visible, it is preferable that the light scattering process is provided only on the facing surface.
Moreover, you may provide the groove | channel structure substantially parallel to the normal line direction of the light-incidence surface mentioned above in the direction which does not perform light-scattering processing among a light emission surface and / or an opposing surface. Providing such a groove structure on the light exit surface and / or the opposing surface can suppress the spread of light emitted from the light exit surface, so that the light guide plate can be made suitable for local dimming.

As another aspect, the light scattering degree of the partial region directly facing the point light source in the region near the light incident surface on the light exit surface and / or the opposing surface of the light guide plate of the present invention is between the point light source and the point light source. It is also possible to provide a light scattering process configured so as to be lower than the light scattering degree of the partial region directly facing the portion.
By providing such light scattering processing on the light exit surface and / or the opposing surface, in combination with the concavo-convex structure provided on the light incident surface (such light scattering processing and the concavo-convex structure provided on the light incident surface are Complementing portions where the luminance unevenness reduction effect is mutually lacking), the uniformity of the luminance of the light exit surface is dramatically improved, and the P / G described later can be increased.
The “partial region directly facing the point light source (or the portion between the point light source and the point light source)” refers to the direction parallel to the light incident surface of the light exit surface as the X axis and the direction perpendicular to the light incident surface as the Y axis. Is a portion of a region having substantially the same Y coordinate, and a partial region having substantially the same X coordinate as a point light source (or a portion between the point light source and the point light source).

  Regarding a region where light scattering processing is performed on the light exit surface and / or the opposing surface (hereinafter also referred to as “light scattering processing region”), “in the region near the light incident surface, light in a partial region directly facing the point light source There is no limitation as long as the condition that the scattering degree is lower than the light scattering degree of the partial region directly facing the portion between the point light source and the point light source is satisfied, not necessarily the light incident surface side It is not necessary that the light scattering processing region starts from the end (Y = 0). For example, when the surface light source device has a frame (a frame having an opening that defines a light emitting area) and the outer peripheral portion of the light emitting surface is covered with this frame, only the central portion of the light emitting surface of the light guide plate emits light. When used as an area, the light scattering processing starts from a position where the overlap between the light scattering processing region and the frame on the light incident surface side is about 10 mm or less (more preferably about 6 mm or less). It is preferable from the viewpoint of in-plane (in the light emitting area) average luminance. However, from the viewpoint of preventing the start line of light scattering processing from being visible when used in a display device or the like, the overlap should be present to some extent, preferably 1 mm or more, more preferably about 2 mm. preferable.

  Specific aspect of configuration in which “in the region near the light incident surface, the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing the portion between the point light source” For example, a. Performing light scattering processing in a region near the light incident surface other than a partial region facing the point light source; b. Performing light scattering processing only on a partial region directly facing a portion between the point light source in the region near the light incident surface; c. Apply light scattering processing to substantially the entire area of the light exit surface and / or the opposing surface so that the light scattering degree of the partial region directly facing the point light source in the region near the light incident surface is lower than the other partial regions, and / or Alternatively, in a region near the light incident surface, a light scattering degree of a partial region directly facing a portion between the point light source and the point light source may be higher than that of other partial regions.

  There is no limitation in light scattering processing, and those generally employed in the field of optical materials can be used. For example, a pattern of a plurality of diffusive dots (hereinafter also simply referred to as “dots”) made of a reflective or diffusive material is provided by stacking or printing, or a pattern of a plurality of three-dimensional dots such as an uneven shape is formed. Forming. There is no limitation in the shape of a dot, For example, circular, a square, etc. are mentioned, The magnitude | size can be about 0.1-2.0 mm, for example.

  The light scattering degree is, for example, the concentration of a reflective (diffusible) substance in a diffusive dot made of a reflective (diffusive) material (the higher the density, the higher the light scattering degree), and the shape of the uneven three-dimensional dot. (For example, the higher the height, the higher the light scattering degree), the proportion of the area where the dots are formed (hereinafter referred to as “dot density”) (the higher the dot density, the higher the light scattering degree) It can be controlled by adjusting). Dot density, for example, changes the area of each dot with a constant number of dots per unit area, or conversely changes the number of dots per unit area with a constant area of each dot (dot pitch) It is possible to make adjustments by changing both of them.

  C18 and C19 show specific examples of light scattering processing. Further, in the example of FIG. C18, by not providing dots in the partial region that faces the point light source in the region near the light incident surface, the light in the partial region that faces the point light source in the region near the light incident surface. The scattering degree is set to be lower than the light scattering degree of the partial region directly facing the portion between the point light source and the point light source. Further, in the example of FIG. C19, the area of each dot in the partial area facing the point light source is small in the area near the light incident surface, and in the area between the point light source and the point light source in the area near the light incident surface. By increasing the area of each dot of the facing partial area, the light scattering degree of the partial area directly facing the point light source in the area near the light incident surface is the light of the partial area facing the part between the point light source and the point light source. It is set to be lower than the scattering degree.

When the light scattering degree is controlled by the dot density, the dot light source ρ1 and the point light source in the region near the light incident surface and the dot density ρ1 of the region having the lowest dot density among the partial regions directly facing the point light source in the region near the light incident surface. The dot density ρ1, so that the ratio (ρ2 / ρ1) of the dot density ρ2 of the region with the highest dot density in the partial region directly facing the portion between the two and P / G described later satisfies the following relationship: It is preferable to adjust ρ2.
2.9 ≦ 1.4 × (P / G) −ρ2 / ρ1 ≦ 3.1
However, when the dot density in each partial area changes stepwise, the dot density of a partial area is the center point of the specific dot (26) included in the partial area and the specific point. Of a polygon (263) that is formed by a perpendicular bisector (26a-f) of a line segment connecting the center point of the dots (A to F) adjacent to the particular dot, and can surround the specific dot With the area as the denominator, the area ratio with the area of the specific dot (26) as the numerator is expressed as a percentage (see FIG. 26).

In order to achieve further uniformity of the light emission distribution on the light exit surface, the light scattering processing further includes a gradation in which the light scattering degree increases toward the direction away from the light entrance surface (for example, dots as the distance from the light entrance surface increases). A gradation that increases the area, and a gradation in which dots having the same area are arranged so that the pitch becomes narrower as they move away from the light incident surface can also be given.
Further, in the case of a surface light source device for a display device, it is preferable that a uniform mountain-shaped light distribution with the highest luminance at the center of the screen is easy to visually recognize while improving the uniformity of the light output distribution. The light scattering processing provided on the light exit surface and / or the opposing surface may be further configured to increase the light scattering degree of the central portion.

The light scattering process described above may be provided on either the light exit surface or the opposing surface, or may be provided on both. However, when the light scattering process is easily visible, it is preferable that the light scattering process is provided only on the facing surface.
Moreover, you may provide the groove | channel structure substantially parallel to the normal line direction of the light-incidence surface mentioned above in the direction which does not perform light-scattering processing among a light emission surface and / or an opposing surface. Providing such a groove structure on the light exit surface and / or the opposing surface can suppress the spread of light emitted from the light exit surface, so that the light guide plate can be made suitable for local dimming.

As yet another aspect, the light exit surface and / or the opposing surface of the light guide plate of the present invention has a light entrance surface in a light shielding portion shielded by a frame (surface light source device) and / or a light shielding frame (display device). A light scattering process configured so that the light scattering degree of the partial area directly facing the point light source is lower than the light scattering degree of the partial area directly facing the part between the point light sources is provided in a nearby area. You can also.
The light scattering processing is performed so that the light scattering degree of the partial region facing the point light source is lower than the light scattering degree of the partial region facing the point light source. By providing it in a region in the vicinity of the light incident surface of the surface, in combination with the concavo-convex structure provided on the light incident surface (the light scattering degree of the partial region directly facing the point light source on such a light emitting surface and / or its opposite surface) The light scattering processing configured to be lower than the light scattering degree of the partial region directly facing between the point light source and the point light source and the uneven structure provided on the light incident surface are insufficient in reducing the uneven brightness. Complementing the portions), the uniformity of the brightness of the light exit surface is dramatically improved, and the P / G described later can be increased.
The “partial region directly facing the point light source (or the portion between the point light source and the point light source)” refers to the direction parallel to the light incident surface of the light exit surface as the X axis and the direction perpendicular to the light incident surface as the Y axis. Is a portion of an area having substantially the same Y coordinate and having an X coordinate substantially the same as that of the point light source (or the portion between the point light source and the point light source). The light scattering degree of the partial region is lower than (or substantially equal to) the light scattering degree of the partial region directly facing the portion between the point light source and the partial region facing the point light source (substantially the point light source) (Partial region having the same X coordinate) The light scattering degree of the partial region directly facing the portion between the point light source and the point light source (partial region having substantially the same X coordinate as the portion between the point light source and the point light source) It is lower (or approximately equal) than the degree of scattering.

The light scattering degree of the partial region directly facing the point light source applied in the light shielding part shielded by the frame (surface light source device) or the light shielding frame (display device) on the light emitting surface and / or the opposing surface is a point light source and a point light source. The light scattering processing that is configured to be lower than the light scattering degree of the partial region that directly faces the portion in between may be applied to at least a part of the region near the light incident surface of the light shielding portion. It is applied in a band-shaped area parallel to the light incident surface of the portion or in a band-shaped area parallel to the light incident surface 1 mm or more (light incident surface side) outside the boundary with the non-light-shielding portion. It is preferable.
Further, this light scattering processing does not necessarily have to start from the light incident surface side end (Y = 0).

The light scattering degree of the partial area directly facing the point light source of the light-shielding part of the light exit surface and / or the opposing surface is configured to be lower than the light scattering degree of the partial area directly facing the part between the point light source and the point light source. A region other than a region subjected to light scattering processing (for example, a boundary area sandwiched between a non-light-shielding portion and the vicinity of a light incident surface (located near the boundary between the light-shielding portion and the non-light-shielding portion), or a light guide plate (Area parallel to the side perpendicular to the light incident surface) may or may not be provided with light scattering processing, but the portion between the point light source and the point light source on the light exit surface (opposite surface) As for the partial region directly facing the surface, it is preferable that the light scattering degree does not change suddenly in the Y-axis direction through the surface (through the light-shielding part and the non-light-shielding part) (the light scattering degree is continuous). So that the degree of light scattering does not change rapidly in the Y-axis direction. It is preferable to provide an appropriate light scattering process.
Further, in the boundary area described above, the light scattering degree of the partial area directly facing the point light source and the light scattering degree of the partial area directly facing the part between the point light source and the point light source may be substantially equal. preferable.

  As a specific aspect of the configuration in which the “light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the region facing the part between the point light source and the point light source”, for example, a. Light scattering processing is performed in a region other than the partial region directly facing the point light source (light scattering processing is performed on the partial region directly facing the portion between the point light source and the point light source), b. Light scattering is applied to almost the entire area in the area near the light entrance surface, and the degree of light scattering is lower in the partial area facing the point light source than in other partial areas (in the part between the point light source and the point light source). For a partial region that faces directly, the degree of light scattering is higher than that of other partial regions).

  There is no limitation in light scattering processing, and those generally employed in the field of optical materials can be used. For example, a pattern of a plurality of diffusive dots (hereinafter also simply referred to as “dots”) made of a reflective or diffusive material is provided by stacking or printing, or a pattern of a plurality of three-dimensional dots such as an uneven shape is formed. Forming. There is no limitation in the shape of a dot, For example, circular, a square, etc. are mentioned, The magnitude | size can be about 0.1-2.0 mm, for example.

  The light scattering degree is, for example, the concentration of a reflective (diffusible) substance in a diffusive dot made of a reflective (diffusive) material (the higher the density, the higher the light scattering degree), and the shape of the uneven three-dimensional dot. (For example, the higher the height, the higher the light scattering degree), and the ratio of the area of the dot-formed portion (hereinafter referred to as “dot density.” In this case, the dot density in the region is surrounded by vertical bisectors 26a to 26f connecting the center of the dot 26 and the centers of the adjacent dots A to F as shown in FIG. It can be controlled by adjusting the ratio (%) of the area of the dot 26 to the area of the square 262, and the higher the dot density, the higher the light scattering degree. Dot density, for example, changes the area of each dot with a constant number of dots per unit area, or conversely changes the number of dots per unit area with a constant area of each dot (dot pitch) It is possible to make adjustments by changing both of them.

  In this aspect, in a region composed of a non-light-shielding portion that is not shielded by the frame (surface light source device) or the light-shielding frame (display device) on the light exit surface and / or the opposing surface of the light guide plate, the partial region directly facing the point light source It is preferable that the light scattering degree of the light source is substantially equal to the light scattering degree of the partial region directly facing the portion between the point light source and the point light source. The non-light-shielding part may or may not be provided with light scattering processing, but for the partial region facing the part between the point light source and the point light source on the light exit surface (opposing surface), through the surface, Since it is preferable that the light scattering degree does not change abruptly in the Y-axis direction (since it is preferable that the light scattering degree is continuous), light scattering is appropriately performed so that the light scattering degree does not change rapidly in the Y-axis direction. It is preferable to provide processing.

  C18 and C19 show specific examples of light scattering processing performed on the light exit surface and / or the opposite surface. Further, in the example of FIG. C18, by not providing a light scattering process in the partial region that faces the point light source in the region near the light incident surface, the partial region that faces the point light source in the region near the light incident surface. The light scattering degree is lower than the light scattering degree of the partial region directly facing the portion between the point light source and the point light source. Further, in the example of FIG. C19, the area of each dot in the partial area facing the point light source is small in the area near the light incident surface, and in the area between the point light source and the point light source in the area near the light incident surface. By increasing the area of each dot of the facing partial area, the light scattering degree of the partial area directly facing the point light source in the area near the light incident surface is the light of the partial area facing the part between the point light source and the point light source. It is set to be lower than the scattering degree.

  FIG. 27 shows a cross-sectional view of an example of the surface light source device and the display device of the present invention. The light emitting area of the surface light source device is defined (limited) by a frame (BL frame), and the display area of the display device is defined (limited) by a light shielding frame (black matrix).

FIG. F28 shows a light scattering process configured such that the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing between the point light source and the light shielding part / non-shielding portion. A specific example of the positional relationship with the light shielding portion will be shown.
In the example of FIG. F28, the light scattering degree of the partial area directly facing the point light source in the light-shielding part (that is, the outside of the display area or the light emitting area) parallel to the light incident surface is the point light source and the point light source. Light scattering processing is performed so that the light scattering degree of the partial area facing the part is lower than the point light source, and the light scattering degree of the partial area facing the point light source is between the point light source and the point light source. In the light scattering processing configured to be lower than the light scattering degree of the partial area directly facing the part, the area of each dot in the partial area directly facing the point light source is reduced in the area near the light incident surface. By increasing the area of each dot in the partial area that faces the portion between the point light source and the point light source in the area near the light surface, the light scattering degree of the partial area that faces the point light source in the area near the light incident surface is increased. Between point light source and point light source It is set to be lower than the degree of light scattering of the positive against partial zones within.
In the non-light-shielding part (that is, the display area or the light emitting area), the light scattering degree of the partial area directly facing the point light source is substantially equal to the light scattering degree of the partial area directly facing the part between the point light source and the point light source. Is light-scattered. Specifically, when the light scattering degree is controlled by the dot density, the dot density ρ1 of the partial area with the lowest dot density and the highest dot density among the partial areas belonging to the same area (partial areas having the same Y coordinate). The ratio (ρ2 / ρ1) of the dot density ρ2 of the partial region is preferably ρ2 / ρ1 ≦ 1.2, more preferably ρ2 / ρ1 ≦ 1.1, and ρ2 / ρ1 = 1. Is most preferred.
A light scattering process configured such that the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing the part between the point light source and the light shielding part / non-light shielding part; Is configured as described above (that is, the light scattering degree of the partial area directly facing the point light source is lower than the light scattering degree of the partial area directly facing the part between the point light source and the point light source) By placing the light scattering process in the light shielding portion), it is possible to prevent the luminance unevenness of the light emitting surface / display surface from being viewed not only from the front but also from the oblique direction.

In FIG.F29, the light scattering processing is configured such that the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing the portion between the point light source and the point light source; Another specific example of the positional relationship between the light shielding part / non-light shielding part will be shown.
In the example of FIG. F29, as in FIG. C18, light scattering processing is performed only on (a part of) a partial area directly facing a portion between the point light source and the point light source in the area near the light incident surface in the light shielding portion. In addition, the light scattering process is not applied to the partial region directly facing the point light source.
Specifically, it is parallel to the light incident surface set outside (light incident surface side) by 0 mm or more (for example, about several mm) from the boundary between the light shielding portion and the non-light shielding portion (display area or light emitting area). Dots are formed at a density two to ten times higher than the dot density of the non-light-shielding portion only in the partial area directly facing the portion between the point light sources in the band-like area B.
In this way, by performing light scattering processing only on the partial region directly facing the portion between the point light source and the point light source of the light shielding portion, a pseudo light source is generated between the point light source and the point light source. By overlapping the image of the point light source, unevenness derived from the point light source can be reduced.
In the example of FIG. F29, in the light shielding portion, the area near the boundary with the non-light shielding portion (boundary area) includes the light scattering degree of the partial region directly facing the point light source and between the point light source and the point light source. Light scattering processing is performed so that the light scattering degree of the partial region facing the portion is substantially equal, and the area A is formed together with the non-light-shielding portion.

The area B is preferably outside by 1 mm or more from the boundary between the light shielding part and the non-light shielding part. By doing so, the above-described pseudo light source can be prevented from being visually recognized by the user when the surface light source device or the display device is used.
In addition, the light scattering processing portion (light scattering processing applied to the partial area directly facing the portion between the point light source and the point light source in the area near the light incident surface) serving as a pseudo light source is the center (point It is preferable to apply a gradation that increases the degree of light scattering toward the middle of the light source and the point light source. By doing so, the light arriving from the left and right point light sources strongly scatters toward the center part between the point light source and the point light source, and the natural pseudo-light source is not generated in the center of the pseudo light source scattering processed part. A light source unit can be provided.

In the case of controlling the light scattering degree by the dot density, the dot density ρ1 of the partial area having the lowest dot density among the partial areas facing the point light source in the area near the light incident surface and the point light source and the point in the area near the light incident surface The dot density so that the ratio (ρ2 / ρ1) of the dot density ρ2 of the partial region having the highest dot density among the partial regions directly facing the portion between the light sources satisfies the following relationship: It is preferable to adjust ρ1 and ρ2.
2.9 ≦ 1.4 × (P / G) −ρ2 / ρ1 ≦ 3.1
However, when the dot density in each partial area changes stepwise, the dot density of a partial area is the center point of the specific dot (26) included in the partial area and the specific point. Of a polygon (263) that is formed by a perpendicular bisector (26a-f) of a line segment connecting the center point of the dots (A to F) adjacent to the particular dot, and can surround the specific dot With the area as the denominator, the area ratio with the area of the specific dot (26) as the numerator is expressed as a percentage (see FIG. 26).

In order to achieve further uniformity of the light distribution on the light exit surface, light scattering processing near the light entrance surface and other light scattering treatments that are appropriately performed are further scattered in the direction away from the light entrance surface. A gradation that increases the degree (for example, a gradation in which the dot area increases as the distance from the light incident surface increases, or a gradation in which dots having the same area are arranged so that the pitch decreases as the distance from the light incident surface) is also given. it can.
Further, in the case of a surface light source device for a display device, it is preferable that a uniform mountain-shaped light distribution with the highest luminance at the center of the screen is easy to visually recognize while improving the uniformity of the light output distribution. The light scattering processing provided on the light exit surface and / or the opposing surface may be further configured to increase the light scattering degree of the central portion.

The light scattering process in the vicinity of the light incident surface described above may be provided on either the light exit surface or the opposing surface, or may be provided on both. However, when the light scattering process is easily visible, it is preferable that the light scattering process is provided only on the facing surface.
Moreover, you may provide the groove | channel structure substantially parallel to the normal line direction of the light-incidence surface mentioned above in the direction which does not perform light-scattering processing among a light emission surface and / or an opposing surface. Providing such a groove structure on the light exit surface and / or the opposing surface can suppress the spread of light emitted from the light exit surface, so that the light guide plate can be made suitable for local dimming.

Next, the surface light source device of the present invention will be described.
FIG. 9 shows a schematic diagram of an example of the surface light source device of the present invention.
The surface light source device 9 of the present invention includes a light guide plate 91, a plurality of point light sources 92 disposed in the vicinity of the light incident surface 93 of the light guide plate, and a frame disposed so as to face the light exit surface of the light guide plate 91 ( (Not shown).

  Although there is no limitation in a point light source, it is preferable to use LED (light emitting diode). Since the LED can obtain high-luminance light with low power consumption and emit light brightly even when the temperature is low, it is possible to provide a surface light source device and a lighting device having sufficient illuminance immediately after lighting. There is no limitation on the type of LED, for example, a one-chip type pseudo white LED that excites green and red phosphors by a blue LED, a multi-chip type that combines white / red / green / blue LEDs to produce white light, and the near ultraviolet One-chip type pseudo white LED that combines an LED and a red / green / blue phosphor may be used.

  FIG. 10 shows a schematic diagram of an example of a box-type LED 10 that can be used in the present invention. The outer shape of the LED and the size of the light emitting surface are not limited, but the outer shape is about 5.6 mm (width) × 3.0 mm (height) × 1.0 mm (thickness), and the lateral width 102 of the light emitting surface 101 is 5 mm. The following are commonly used:

  The distance between the light emitting surface of the point light source and the light incident surface of the light guide plate is preferably 0.1 mm or more and 1.5 mm or less. More preferably, it is 0.3 mm or more and 1.0 mm or less. When the distance between the light guide plate and the light emitting surface is increased, the amount of light incident on the light guide plate is reduced by the inverse square law, and as a result, the total amount of light emitted from the light output surface is also reduced. Therefore, the distance between the light emitting surface of the point light source and the light incident surface of the light guide plate is preferably short. On the other hand, since heat is generated around the point light source and the light guide plate expands, it is necessary to leave a gap that can withstand the expansion.

  Although there is no limitation on the arrangement method of the point light source, it is arranged on the straight line along the light incident surface of the light guide plate (parallel to the light emitting surface) at regular intervals (“equal interval” includes an error of ± 10%). It is preferable to do. In this case, the arrangement pitch P of the point light sources is generally, for example, about the width (outer shape) of the point light source to about 200 mm. From the viewpoint of preventing uneven brightness, the point light sources are preferably arranged as densely as possible, and in view of mounting restrictions on the substrate, it is preferable that the distance is increased to some extent. The arrangement pitch of the point light sources is preferably 5 mm to 200 mm, more preferably 10 to 100 mm.

  However, in the surface light source device of the present invention, the light guide plate with reduced luminance unevenness in the vicinity of the light incident surface on the light exit surface is used as the light guide plate, so even if the arrangement pitch of the point light sources is somewhat large, No light exit surface can be realized. Specifically, for example, if it is about 20 mm to 50 mm, 30 mm to 50 mm, or 40 mm to 50 mm, the luminance unevenness can be suppressed within an allowable range.

  In the above, description has been made on the assumption that the LED is a Lambertian LED as shown in FIG. A Lambertian LED is an LED having a light emitting surface that is substantially flat and has a layer in which a highly diffusible phosphor is dispersed inside, and emits light with a light distribution close to the Lambert model in all directions. Is a feature.

  Here, the effect of the concavo-convex structure provided on the light incident surface of the light guide plate of the present invention is not simply that the light is spread by the concavo-convex structure, but the light originally emitted from the LED in a wide direction is from the light incident surface. When the light enters the light guide plate, the spread is prevented from being suppressed by refraction as shown in FIG. K4, and the light is made incident at a wide angle as shown in FIG. K5.

  Therefore, if a high diffusion LED having a lens as shown in FIG. K2 is used as a point light source, the angle distribution of the light emission intensity of the LED can be as shown in FIG. Can distribute light. Light in a wide angle direction can enter the light guide plate at a wide angle through the uneven surface as shown in FIG. K5.

Therefore, in the present invention, as a point light source, an LED (high diffusion LED) having a lens in which a portion facing the center of the LED in a cross section cut parallel to the length direction of the light incident surface is recessed on the surface. It is also preferable to use it.
By combining the uneven structure on the light incident surface of the light guide plate and the above-described high diffusion LED (for example, FIG. K6), the hot spot suppressing ability greatly exceeds the effect obtained by the combination of the Lambertian LED and the uneven structure. As a result, it contributes to the reduction of LEDs and the narrowing of frames. In addition, the effect can be further increased by a combination with the light emitting surface and / or the light scattering processing of the opposing surface represented by FIG.

The surface light source device of the present invention further includes a frame that defines a light emitting area (irradiation area) of the surface light source device, which is disposed to face the light exit surface of the light guide plate. The frame is made of a material that does not transmit the light from the point light source, and the region corresponding to the light emitting area is made of, for example, an opening.
The frame may further include a cover portion that can accommodate the light guide plate and the point light source therein, and the surface light source device may have a clean appearance by concealing the light source and the like therein. it can.

The frame is configured such that the light emitting area starts from the inside of the light incident surface of the light guide plate.
Furthermore, in the case where the light scattering surface as described above is applied to the light exit surface and / or the facing surface of the light guide plate, the light emitting area is near the light entrance surface of the light exit surface and / or the facing surface of the light guide plate, The light scattering degree of the partial region that faces the point light source is lower than the light scattering processing that is configured so that the light scattering degree of the partial region that faces the part between the point light source and the point light source is lower. It is preferable to be configured to start from the inside.
In other words, the region where the light scattering surface of the light guide plate and / or the opposite surface is subjected to the light scattering process is outside of the range facing the opening of the frame on at least one light incident surface side, preferably 0 to 0. 10 mm (excluding 0 mm), more preferably 1 to 6 mm, still more preferably 1 to 4 mm, and particularly preferably 2 mm outside. If it does in this way, while there is no possibility that the start line of light scattering processing can be visually recognized from the screen side, high in-plane (light-emitting area) average brightness can be secured.

  In the surface light source device of the present invention, in addition to the light guide plate, the point light source, and the frame, an optical element generally employed in a so-called edge light type surface light source device such as a diffusion sheet and a reflection sheet can be further included. Specifically, the diffusion sheet can be disposed above the light exit surface of the light guide plate, and the reflection sheet can be disposed below the facing surface of the light guide plate. Furthermore, above the light exit surface of the light guide plate, in addition to the diffusion sheet, a polarizing sheet for avoiding optical loss in a prism sheet, a condensing sheet such as a lenticular lens sheet and a micro lens sheet, and a polarizing plate of a liquid crystal panel A reflection sheet or the like can also be arranged.

  In particular, when a lens sheet having a groove structure having a ridge line substantially perpendicular to the light incident surface on which the LEDs are arranged is laminated above the light exit surface of the light guide plate, the luminance unevenness reducing effect of the present invention is very strong. Since it is obtained, the lens sheet is preferably a prism sheet in which the groove structure is formed of a substantially triangular prism. In addition, it is preferable to combine a lens sheet having a groove structure having a ridge line substantially parallel to the light incident surface on which the LEDs are disposed, since luminance unevenness when viewed from an oblique direction is improved. In this case, it is preferable to interpose a diffusion sheet between the prism sheet and the light guide plate because light scattering processing of the light guide plate becomes difficult to be visually recognized and fine unevenness is improved. Further, in order to prevent the optical sheet from being damaged due to interference with the display panel used in combination, a diffusion sheet is provided on the outermost side (the diffusion property is lower than the diffusion property of the diffusion sheet described above). It is preferable to dispose.

  In the surface light source device of the present invention, in particular, a prism sheet having, on the surface thereof, a groove structure having at least a ridge line substantially perpendicular to the light incident surface on which the diffusion sheet and the LED are disposed above the light exit surface of the light guide plate. When four optical sheets, a prism sheet having a groove structure having a ridge line substantially parallel to the light incident surface on which the LEDs are arranged, and a diffusion sheet, are laminated in this order (see FIG. 23), luminance is increased. A very high-quality surface light source device is obtained in which there is almost no unevenness and the light scattering processing provided on the light guide plate is not visually recognized.

As the prism sheet and the diffusion sheet, those generally used in a surface light source device or the like can be used. For example, as a diffusion sheet (hereinafter referred to as “lower diffusion sheet”) in contact with the light exit surface of the light guide plate, the total thickness is 215 μm, and the breakdown is several μm to several on the display surface side on the 188 μm thick PET substrate. Transparent particles such as silica beads of the order of 10 μm are dispersed, and the beads are coated with UV or thermosetting resin as a binder around 10 μm thick (wherein most of the beads are coated so as to protrude from the binder). Thus, an appropriate diffusibility and light collecting property are obtained), and a coating layer for preventing charging and adhesion is provided on the opposite side as viewed from the display surface side with a thickness of about 10 μm (by the coating layer, This prevents problems caused by adhesion to the light guide plate, etc. A small amount of beads and a fatty acid salt for reducing the surface resistance are added to this coating layer. That.
The diffusion sheet disposed on the display surface side (hereinafter referred to as “upper diffusion sheet”) has a total thickness of 220 μm, and the breakdown is several μm to several tens of μm on the display surface side on the 188 μm thick PET substrate.
Transparent particles such as m-order silica beads are dispersed less than the lower diffusion sheet, and the beads are coated with a UV or thermosetting resin around 10 μm thick as a binder (where most of the beads are embedded in the binder) It is coated to prevent damage due to interference with the panel, etc. while suppressing appropriate diffusivity.) On the opposite side as seen from the display surface side, it prevents charging and adhesion as well as the lower diffusion sheet. (The coating layer prevents defects due to adhesion to the prism sheet. The coating layer includes a small amount of beads and a fatty acid salt for reducing surface resistance.) In the case of an upper diffusion sheet, the display surface side often takes the same design from the viewpoint of preventing adhesion to the panel.) Can do.

  As the prism sheet, for example, an optical sheet in which a UV curable resin is formed on a display surface side of a PET substrate having a thickness of 250 μm and a prism having a thickness of 15 μm to 20 μm and an apex angle of approximately 90 ° is formed at a pitch of approximately 50 μm. Can be used. On the opposite side when viewed from the display surface side, a coating layer for preventing charging and adhesion is provided in a thickness of 15 μm to 20 μm like the diffusion sheet, and adhesion with other laminated optical sheets and friction It prevents problems such as scratches due to increased coefficients. A small amount of beads and a fatty acid salt for reducing the surface resistance are added to this coat layer.

  The surface light source device may include a power source that supplies power to the point light source, and may include a control circuit that controls the amount of current and on / off.

The surface light source device of the present invention can also be used as a general lighting device. The case where the surface light source device of the present invention is used for a general lighting device will be described below.
FIG. C2-11 shows a sectional view of an example of the lighting device of the present invention (indoor ceiling lighting), and FIG. C2-9 shows a schematic diagram of the inside thereof.
The illumination device C2-9 of the present invention includes a frame C2-90 (not shown in FIG. 9) having an opening C2-901 that defines a light emitting area (irradiation area), a light guide plate C2-91, and a light guide plate. And a plurality of point light sources (not shown in FIG. C2-11) arranged in the vicinity of the light incident surface (the back surface of the frame).

Even when the surface light source device of the present invention is used as a general lighting device, the point light source is not limited, but an LED (light emitting diode) is preferably used. Since the LED can obtain high-luminance light with low power consumption and emit light brightly even when the room temperature is low, it is possible to provide an illumination device having sufficient illuminance immediately after lighting. There is no limitation on the type of LED, for example, a one-chip type pseudo white LED that excites green and red phosphors (or yellow phosphors such as YAG) by blue LEDs, and two or more blue LED chips in one LED package 2in1 pseudo white LED that excites green and red phosphors (or yellow phosphors such as YAG), multi-color chip type that combines red / green / blue LEDs to produce white light, and near ultraviolet LED A one-chip type pseudo white LED in which red / green / blue phosphors are combined is exemplified.
FIG. 10 shows a schematic diagram of an example of a box-type LED 10 that can be used. There is no limitation on the outer shape of the LED and the size of the light emitting surface. In the backlight of a liquid crystal display device or the like, the outer shape is generally about 5.6 mm (width) × 3.0 mm (height) × 1.0 mm (thickness), and the width 102 of the light emitting surface 101 is generally 5 mm or less. However, in general lighting devices, those slightly larger than those used in backlights such as liquid crystal display devices are preferable, and the outer shape is 6.0 mm (width) × 5.0 mm (height) × 1. It is preferable that the width 102 of the light-emitting surface 101 is about 5.5 mm (thickness) or less and about 5.5 mm or less.
Moreover, although the supply current of a general LED is about 20 mA to 160 mA, a large chip type high output LED having a supply current of 200 mA to 1 A class can also be used in a general lighting device. When such a high-power LED is used, the number of LEDs to be used is drastically reduced and the manufacturing cost is reduced. On the other hand, the problem of hot spots is increased. Therefore, the effect of the present invention of reducing hot spots becomes more important.

The distance between the light emitting surface of the point light source and the light incident surface of the light guide plate is preferably 0.1 mm or more and 1.5 mm or less. More preferably, it is 0.3 mm or more and 1.0 mm or less.
This is because if the distance between the light guide plate and the light emitting surface is increased, the amount of light incident on the light guide plate is reduced by the inverse square law, and as a result, the total amount of light emitted from the light exit surface is also reduced. Therefore, the distance between the light emitting surface of the point light source and the light incident surface of the light guide plate is preferably close. Further, since heat is generated around the point light source and the light guide plate expands, it is necessary to leave a gap that can withstand the expansion.

Although there is no limitation on the arrangement method of the point light source, it is arranged on the straight line along the light incident surface of the light guide plate (parallel to the light emitting surface) at regular intervals (“equal interval” includes an error of ± 10%). It is preferable to do. In this case, the arrangement pitch P of the point light sources can be, for example, about the width (outer shape) of the point light source to about 200 mm. From the viewpoint of preventing luminance unevenness, the point light sources are preferably arranged as densely as possible, and it is preferable that the distance is increased to some extent from the viewpoint of mounting restrictions on the substrate and manufacturing cost. The arrangement pitch of the point light sources is preferably 6 mm to 200 mm, more preferably 10 to 100 mm.
However, in the present invention, a light guide plate in which luminance unevenness in the vicinity of the light incident surface on the light exit surface is reduced is used as the light guide plate. Therefore, even if the arrangement pitch of the point light sources is somewhat large, specifically, 80 mm to 200 mm. Even if it is about 100 mm to 200 mm, or about 120 mm to 200 mm, a light exit surface with suppressed hot spots can be realized.

The frame may be configured such that the light guide plate or the point light source can be accommodated therein, whereby the light source or the like can be hidden behind the frame to make the lighting device have a clean appearance.
Since luminance unevenness occurs in the vicinity of the light incident surface of the light guide plate, the opening of the frame is preferably designed such that the light emitting area starts from the inside of the light incident surface of the light guide plate.
That is, the horizontal distance G between the light incident surface 93 of the light guide plate 91 and the opening of the frame (the region 94 and the light incident surface 93 when the region 94 corresponding to the frame opening is projected on the light guide plate 91) Is preferably designed so as to ensure a certain distance (see FIG. 9).

However, in the light guide plate of the present invention, the luminance unevenness in the vicinity of the light incident surface is reduced. Therefore, in a general lighting device using the light guide plate, it is necessary to form the light emitting area on the inner side as the conventional light guide plate is used. No (no need to increase G).
Specifically, the horizontal distance G between the light incident surface of the light guide plate and the display area can be set to G <P (P / G> 1) with respect to the arrangement pitch P of the point light sources. May be G <P / 2 (P / G> 2), or G <P / 4 (P / G> 4).
If the relationship between P and G can be designed as described above, a stylish lighting device with a thin frame can be realized, and the number of point light sources to be used can be reduced. I can plan. In addition, although the magnitude | size of G is decided by balance with P as above-mentioned, it can be set to 0.1-30 mm, 0.1-20 mm, or 0.1-10 mm, for example.
In addition, as shown in the Example mentioned later, even if it changes the arrangement pitch P of a point light source, or even if the horizontal distance G between the light-incidence surface of a light-guide plate and a light emission area is changed, P / G will be. If the value is the same, the same luminance unevenness reduction performance is exhibited.

When the light guide plate has two light incident surfaces, the arrangement pitch of the point light sources arranged near the first light incident surface is P1, and the arrangement pitch of the point light sources arranged near the second light incident surface is P1 / G1: where P2, the horizontal distance between the first light incident surface and the opening is G1, and the horizontal distance between the second light incident surface and the opening is G2. P2 / G2 = 100: 90 to 100: 110 is preferable, P1 / G1: P2 / G2 = 100: 95 to 100: 105 is more preferable, and P1 / G1 = P2 / G2 is preferred.
G1 and G2 are not necessarily the same.

  The general lighting device may further include optical elements such as a diffusion sheet and a reflection sheet in addition to the light guide plate and the point light source. Specifically, the diffusion sheet can be disposed so as to face the light exit surface side of the light guide plate, or the reflection sheet can be disposed so as to face the facing surface side of the light guide plate. In addition to the diffusion sheet, a light collecting sheet such as a prism sheet, a lenticular lens sheet, or a microlens sheet can be disposed on the light exit surface side of the light guide plate. In addition, a power source that supplies power to the point light source may be included, and a control circuit that controls the amount of current and on / off may be included.

In the general lighting device, a cover may be provided on the light exit surface side of the light guide plate for the purpose of preventing contamination.
Moreover, when using as an evacuation guide light (FIG. C2-12), the panel which displays an evacuee's guidance direction is arrange | positioned on the light emission surface side of a light-guide plate.

When the surface light source device of the present invention is used as a general lighting device, the maximum luminance is not limited, but the luminance unevenness is improved in the surface light source device of the present invention. If the brightness of the bright part is equal to or less than the surface brightness of the HCFL (hot cathode tube, so-called fluorescent lamp) widely used in general lighting devices, the performance as general lighting is sufficient. In addition, the user is not dazzled. From such a point of view, in the general lighting device using the surface light source device of the present invention, the maximum luminance of the light emitting surface when lighting a plurality of point light sources is 10,000 cd / m ² or less regardless of which direction is measured. It is preferably 8,000 cd / m ^{2 to} 10,000 cd / m ^2, more preferably 9,000 cd / m ^{2 to} 10,000 d / cm ² .

Next, the display device of the present invention will be described.
A display device according to the present invention includes a display panel having a display area for displaying light by adjusting light transmission of the surface light source device, a light shielding frame for defining the display area, and a surface light source device disposed on the back surface of the display panel. And have.
In the display device of the present invention, the surface light source device described above can be used as the surface light source device.

The display area (active area) of the display panel should be designed to start from the inside of the light incident surface of the light guide plate, because uneven brightness occurs near the light incident surface of the light guide plate and sufficient display quality cannot be guaranteed. Is preferred.
That is, the horizontal distance G between the light incident surface 93 of the light guide plate 91 and the display area (the distance between the region 94 and the light incident surface 93 when the region 94 corresponding to the display area is projected on the light guide plate 91 ( It is preferably designed to ensure a certain level or more).

  However, since the light guide plate of the present invention has reduced luminance unevenness in the vicinity of the light incident surface, in the display device of the present invention using the light guide plate, the display area is formed on the inner side as the conventional light guide plate is used. There is no need to do this (G need not be increased).

  Specifically, in the display device of the present invention, the horizontal distance G between the light incident surface of the light guide plate and the display area is set to G <P / 2.5 (P /G>2.5), or G <P / 3 (P / G> 3) and G <P / 4 (P / G> 4).

  If the relationship between P and G can be designed as described above, a stylish display device in which the outer frame portion of the display area formed on the display panel called a frame is thin can be realized and used. Since the number of point light sources can be reduced, power can be saved. It should be noted that the relationship between P and G in the conventional display device is at most about P / G ≦ 0.7. In addition, although the magnitude | size of G is decided by balance with P as above-mentioned, it can be set to 0.1-30 mm, 0.1-20 mm, or 0.1-10 mm, for example.

  Even if the arrangement pitch P of the point light sources is changed or the horizontal distance G between the light incident surface of the light guide plate and the display area is changed, if the P / G is the same value, the same luminance unevenness reduction performance Indicates.

  When the light guide plate included in the display device of the present invention has two light incident surfaces, the arrangement pitch of the point light sources disposed in the vicinity of the first light incident surface is P1, and is disposed in the vicinity of the second light incident surface. The arrangement pitch of the point light sources is P2, the horizontal distance between the first light incident surface and the display area is G1, and the horizontal distance between the second light incident surface and the display area is G2. P1 / G1: P2 / G2 = 100: 90 to 100: 110 is preferable, and P1 / G1: P2 / G2 = 100: 95 to 100: 105 is preferable. More preferred.

  G1 and G2 are not necessarily the same. For example, since a speaker or the like may be provided on the lower side portion of the display device, it is possible to reduce G only on the lower side portion in order to secure a space.

  The display panel is preferably a liquid crystal display panel. Conventionally used liquid crystal display panels can be used as the liquid crystal display panel. An example of the configuration is schematically shown in FIG. 11 and described below.

  FIG. 11 is a schematic front view of an example of the liquid crystal display panel 11. The outer side of the dotted line 111 is a light shielding frame (black matrix) 113, and the inner side is a display area 112. Panel wiring (not shown) and the like exist behind the light shielding frame (black matrix) 113. In FIG. 11, reference numerals 114 and 115 denote a source chip which is a driver IC for applying a voltage to a source line (described later, not shown) and a voltage for applying a voltage to a gate line (described later, not shown). It is a gate chip which is a driver IC.

  In a transmissive liquid crystal display panel, generally, a large number of pixel electrodes arranged in a matrix on a transparent substrate are driven by active matrix elements arranged on the transparent substrate. An active matrix substrate in which an active matrix element and pixel electrodes are provided on a transparent substrate is provided with a liquid crystal layer in a stacked state, and a counter substrate is disposed so as to face the active matrix substrate with the liquid crystal layer interposed therebetween. ing. The counter substrate is a transparent substrate provided with a counter electrode, and this counter electrode is opposed to the display region in the liquid crystal layer.

  The active matrix element provided on the active matrix substrate is provided with a TFT (thin film transistor) as an active element connected to each pixel electrode. The active matrix element includes a plurality of gate lines arranged in parallel to each other along the row direction and a plurality of source lines arranged in parallel to each other along the column direction orthogonal to each gate line. Each TFT is disposed in the vicinity of the intersection between each gate line and each source line. Each TFT is connected to each of a gate line and a source line that form adjacent intersections.

  Each TFT is configured to be turned on by a gate signal supplied from a gate line to which each TFT is connected, and to supply a source signal supplied from a source line to which each TFT is connected to a pixel electrode connected thereto. Has been.

  In such a liquid crystal display panel, gate signals (horizontal synchronization) are usually line-sequentially arranged in the order along the column direction for each gate line arranged along the row direction on the active matrix substrate for each frame. Signal), and gate signals are continuously supplied to gate lines adjacent in the column direction.

The display panel of the display device of the present invention has a light shielding frame that defines a display area of the display device.
The light shielding frame is made of a material that does not transmit the light from the point light source, and the region corresponding to the display area is an opening or is made of a material that transmits the light from the point light source. A specific example of such a light shielding frame includes a glass substrate on which a color filter mixed with a light shielding agent such as carbon black is applied only to a region (frame portion) other than the display area.

The light shielding frame is configured so that the display area of the display device starts from the inside of the light incident surface of the light guide plate, and the display area is provided near the light incident surface of the light guide plate and / or the opposing surface. The light scattering degree of the region facing the light source is configured to start from the inner side of the light scattering processing configured to be lower than the light scattering degree of the region facing the part between the light source and the light source.
In other words, the region where the light scattering surface of the light exit surface and / or the opposing surface of the light guide plate is subjected to the light scattering processing is outside of the line facing the inner frame of the light shielding frame on the at least one light incident surface side, preferably 0. 10 mm (however, 0 mm is not included), more preferably 1 to 6 mm, still more preferably 1 to 4 mm, and particularly preferably 2 mm outside. In this way, there is no possibility that the start line of the light scattering process can be visually recognized from the screen side, and high in-plane (display area) average luminance can be ensured.

  The display device of the present invention can be used for various applications such as a portable information terminal and a monitor of a personal computer. For example, by combining the display device of the present invention with a tuner that receives a broadcast video signal, the television receiver of the present invention can be obtained. FIG. 12 shows an example of the configuration of such a television receiver 12. 12 includes a display cabinet 121 of the present invention, a front cabinet 122 provided with a speaker 1221; various circuit boards such as a television tuner circuit board 123, a power supply circuit board 124, and a control circuit board 125; 126, stand 127 and the like.

Next, a resin layer (light diffusion layer) which is bonded to the light incident surface of the light guide plate used in the present invention and has a plurality of concave portions or convex portions having an anisotropic shape with a long opening or bottom surface in one direction. The first invention of the present application relating to the light diffusing layer of the diffusing sheet, which can also be suitably used as a).
Description 1st invention relates to the diffusion sheet used for back lighting, such as a liquid crystal display device, especially to the light-diffusion layer.

Currently, liquid crystal display devices are used in a wide range of fields such as mobile phones, PDA terminals, digital cameras, televisions, personal computer displays, and notebook computers.
When the light source unit used in the liquid crystal display device is roughly classified, when the liquid crystal display panel arrangement side is set to the upper side, a direct type light source unit having a configuration in which a plurality of light sources are arranged directly under the liquid crystal display panel, and an arrangement directly under the liquid crystal panel There is an edge light type light source unit having a configuration in which a light source is arranged on the side end face of the light guide.

The light source unit used in the various liquid crystal display devices as described above is required to supply uniform light to the liquid crystal display panel and supply as much light as possible in order to make the display image easy to see.
That is, the light source unit is required to have optical characteristics that are excellent in light diffusibility and high brightness.

By the way, in the edge light type light source unit described above, since the light source is arranged on the side end surface of the light guide, the light source unit itself can be thinned. However, the luminance is lowered by passing the light guide. It has the disadvantage of becoming.
On the other hand, the direct type light source unit has an advantage that high luminance can be obtained, but has a disadvantage that the luminance between the upper part of the light source on the liquid crystal display panel surface and the upper part between the light sources tends to be uneven. have. Therefore, in the direct type light source unit, an optical sheet having a function of diffusing light with a certain distance between the light source and the liquid crystal display panel, for example, a diffusion plate, is disposed between the light source and the liquid crystal display panel. I am doing so.

  As the diffusing plate, a resin plate containing light diffusing particles and bubbles, or a structure having a fine uneven shape on the surface of a transparent substrate are known. The latter with less loss of light transmittance is more preferable.

  As a method of imparting the uneven shape to the surface of the diffusion plate, there are a method of injection molding a resin using a predetermined mold, and a method of processing the uneven structure into a roll with a diamond blade and extrusion using the method. is there.

However, the method of mechanically forming the unevenness as described above has a problem that it takes a lot of time and is expensive. Further, in the method of mechanically forming the unevenness as described above, there is a problem that the structure of about several tens of μm is the limit, and further, it is not easy to improve the shape uniformity.
On the other hand, the concave / convex shape is recorded on the photosensitive medium by the speckle of the laser beam, and a mold for pattern transfer is manufactured. A technique for forming a holographic light guide plate by forming irregularities on the surface is proposed (see, for example, FIG. 41 in JP-A-2001-23422).

On the other hand, in recent years, liquid crystal display devices have been made thinner, and the distance between a light source and an optical sheet (for example, the above-described hologram light guide plate and diffusion plate) for diffusing light from the light source. There is a request to make more.
There is also a demand to reduce the number of light sources in the light source unit in order to reduce cost and power consumption.

However, as schematically shown in FIGS. B1 (a) and (b), in the light source unit, the ratio of the pitch (p) of the light source to the distance (h) between the light source B1 and the optical sheet B2 (p / As h) becomes larger, that is, as h becomes smaller (ha in FIG. B1 (a)) and / or p becomes larger (pa in FIG. B1 (b)), the luminance unevenness becomes more conspicuous.
Here, “brightness unevenness” refers to a phenomenon in which light and darkness derived from the intensity distribution of light source illuminance can be seen on the screen of a liquid crystal display panel.
Liquid crystal display devices are required to reduce such luminance unevenness.

In the prior art disclosed in Japanese Patent Laid-Open No. 2001-23422, the luminance unevenness cannot be sufficiently reduced, and the liquid crystal display device cannot be made thin and the number of light sources can be reduced.
SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, the object of the present invention is to provide a diffusion sheet and a light source unit that can reduce luminance unevenness.

The inventor of the specification first invention has intensively studied to solve the above-described problems of the related art relating to the diffusion sheet. As a result, the light diffusion layer is formed of a specific material and has a specific refractive index. The inventors have found that the above-described problems of the prior art can be solved by the diffusion sheet, and have completed the first invention of the specification.
The first invention of the specification is as follows.

[1]
A diffusion sheet in which a resin layer having an uneven structure is laminated on at least one main surface of a sheet-like base material,
The refractive index of the resin layer is 1.55 to 1.70,
And the resin layer is
Photopolymerizable resin containing (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group: 70 to 99.9% by mass, and (B) photopolymerization initiator: 0.1 to 30% by mass Consisting of a cured product of the composition,
The diffusion sheet containing (A) a compound having a structure represented by the following general formula (I) in which the addition polymerizable monomer having at least one terminal ethylenically unsaturated group has a biphenyl group.

Formula (I)

(In general formula (I), R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.)

  The compound having the structure represented by the general formula (I) is preferably a compound represented by the following general formula (II).

Formula (II)

  In general formula (II), R represents a hydrogen atom or a methyl group, A represents a C1-C4 alkylene group each independently, and n represents an integer of 1-3.

[2]
The content of the compound having the structure represented by the general formula (I) or (II) in the addition polymerizable monomer (A) having at least one terminal ethylenically unsaturated group is 50 to 95% by mass. The diffusion sheet according to [1].

[3]
The diffusion sheet according to [1] or [2], wherein a diffusion angle periodically changes along a predetermined direction in the surface of the diffusion sheet when a light beam is incident on the surface of the diffusion sheet in a vertical direction.

[4]
In the diffusion angle distribution diagram taking the relative position in the predetermined direction in the diffusion sheet surface on the horizontal axis, the diffusion angle in the relative position on the vertical axis,
There are a plurality of peak points at which the diffusion angle indicates a peak value and a plurality of bottom points at which the diffusion angle indicates a bottom value, and the arithmetic average value of the peak value and the bottom value indicated by the adjacent peak point and the bottom point is The diffusion sheet according to [3], which is larger than an arithmetic average value of diffusion angles at all points distributed between the adjacent peak point and bottom point.

[5]
The diffusion sheet according to any one of [1] to [4], wherein a diffusion angle is controlled by the uneven structure.

[6]
The concavo-convex structure is a concavo-convex structure formed using a speckle pattern by interference exposure, and the diffusion angle is controlled by the average size and shape of speckles of the concavo-convex structure. ] The diffusion sheet as described in any one of.

[7]
A light source unit comprising two or more light sources and the diffusion sheet according to any one of [1] to [6] disposed to face the light sources.

[8]
The light source unit according to [7], wherein the light source is a linear light source.

[9]
The light source unit according to [7], wherein the light source is a point light source.

[10]
A period of diffusion angle distribution of the diffusion sheet;
Period of illuminance distribution on the light incident surface of the diffusion sheet;
Is the light source unit according to any one of [7] to [9].

[11]
A diffusion plate containing a diffusing agent is disposed between the diffusion sheet and the light source, and a reflection sheet is disposed on the opposite side of the diffusion plate from the light source via the light source. [7] The light source unit according to any one of [10].

[12]
The light source unit according to any one of [7] to [11], wherein a surface-shaped diffusion sheet is further arranged on the diffusion sheet arrangement side.

[13]
The light source unit according to any one of [7] to [12], wherein a prism sheet is further arranged on the diffusion sheet arrangement side.

[14]
The light source unit according to any one of [7] to [13], wherein a reflective polarizing sheet is further arranged on the diffusion sheet arrangement side.

[15]
A liquid crystal display panel, and the light source unit according to any one of [7] to [14] for supplying light to the liquid crystal display panel,
A liquid crystal display device in which the light source unit is disposed on the back side of the liquid crystal display panel, and display is performed by entering light from the light source unit.

  According to the first invention of the specification, a diffusion sheet, a light source unit, and a liquid crystal display device using the diffusion sheet that can effectively reduce luminance unevenness can be obtained.

Hereinafter, modes for carrying out the specification first invention (hereinafter referred to as embodiments) will be described with reference to the drawings.
In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
Further, in each drawing, unless otherwise specified, the positional relationship such as up, down, left, and right is based on the positional relationship shown in the drawing, and the dimensional ratio in the drawing is not limited to the illustrated ratio.
Furthermore, in the present specification, the term “abbreviated” indicates the meaning of the term excluding the “abbreviation” within the scope of technical common knowledge of those skilled in the art, Shall also be included.

[Diffusion sheet]
In the diffusion sheet of the embodiment, a resin layer having a concavo-convex structure is laminated on at least one main surface of a sheet-like substrate.
The refractive index of the resin layer is 1.55 to 1.70,
And the resin layer is
(A) Addition polymerizable monomer having at least one terminal ethylenically unsaturated group: 70 to 99.9% by mass, (B) Photopolymerization initiator: Photopolymerizable resin composition containing 0.1 to 30% by mass Made of cured products,
The (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group contains a compound having a structure represented by the following general formula (I) having a biphenyl group.

Formula (I)

(In general formula (I), R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.)

  The compound having a structure represented by the general formula (I) preferably has a structure represented by the following general formula (II).

Formula (II)

  In general formula (II), R represents a hydrogen atom or a methyl group, A represents a C1-C4 alkylene group each independently, and n represents an integer of 1-3.

(Base material)
The base material constituting the diffusion sheet of the embodiment is a sheet-like base material, and may be a light-transmitting base material made of a material such as resin or glass. In particular, the light transmittance of the base material alone is 75. % Or more is preferable.
In this case, “light” is not particularly limited as long as it is visible light, but is, for example, light emitted from a light source in a light source unit using the diffusion sheet of the embodiment.
The light transmittance is determined by, for example, using a UV-visible spectrophotometer (MPC-2200) manufactured by Shimadzu Corporation, and setting the base material between the light source and the detector, and the incident light intensity at a wavelength of 550 nm. And after detecting transmitted light intensity, it is computable by following formula (II).
Light transmittance (%) = (transmitted light intensity at 550 nm) / (incident light intensity at 550 nm) × 100 (II)
Although the thickness of a base material is not specifically limited, Usually, it exists in the range of 50 micrometers-500 micrometers.
Examples of the resin material of the substrate include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, acrylic resins such as polymethyl methacrylate, thermoplastic resins such as polycarbonate resin, polystyrene resin, and polymethylpentene resin, and polyester. Examples include resins obtained by curing an ionizing radiation curable resin composed of oligomers such as acrylate, urethane acrylate, epoxy acrylate, and / or acrylate monomers with electromagnetic radiation such as ultraviolet rays or electron beams.
As the glass, soda glass, borosilicate glass, or the like is used.

(Resin layer)
<Uneven structure>
The resin layer is formed on at least one main surface of the base material described above and has a concavo-convex structure.
The said main surface means the surface and the back surface when not including the thickness part of the base material mentioned above and seeing a base material as a plane.
The uneven structure is a structure in which a large number of protrusions are provided on the surface.
The shape of the protrusion is not particularly limited, and examples thereof include a substantially conical shape, a substantially spherical shape, a substantially ellipsoidal shape, a substantially lenticular lens shape, and a substantially parabolic shape.
The protrusions may be regularly arranged or irregularly arranged. Further, the protrusions may be connected by a continuous curved surface.
Further, a pseudo random structure in which irregular irregularities are connected by a continuous curved surface can also be preferably used. This pseudo-random structure is preferably a fine three-dimensional structure characterized by non-planar speckles.

  In order to obtain favorable characteristics regarding the light diffusion performance, the height of the protrusions is preferably in the range of 1 μm to 15 μm, and the pitch is preferably in the range of 1 μm to 30 μm.

The three-dimensional structure characterized by the non-planar speckle is suitable for forming a fine concavo-convex structure of 10 μm or less, which is difficult by machining.
In particular, the method of forming irregularities using non-planar speckles is a manufacturing method suitable when the diffusion angle is changed according to the region on the diffusion sheet.
A method for manufacturing the concavo-convex structure using this non-planar speckle will be described later.

  An isotropic uneven structure such as a microlens and an anisotropic uneven structure such as a lenticular lens are also preferable as the uneven structure of the resin layer of the diffusion sheet.

The uneven structure formed in the resin layer of the diffusion sheet preferably has an irregular height and pitch from the viewpoint of suppressing moire.
When the uneven shape is present on the surface of the sheet, it becomes possible to diffuse the light incident on the diffusion sheet.

  The diffusion sheet of the embodiment may be any part of the sheet surface where the uneven shape as described above is arranged and has a portion showing a function of diffusing light, and a portion that does not need to have a diffusion function, for example, an end In the portion, there may be a portion where the sheet surface is smooth.

<Refractive index>
The refractive index of the resin layer of the diffusion sheet of the embodiment is 1.55 to 1.70.
The refractive index of the resin layer is measured according to JIS K7142, and specifically, can be measured using a refractometer MODEL 2 010 PRISM COUPLER (manufactured by Metricon) manufactured by Metricon.
If the refractive index of the resin layer is 1.55 or more, light from the light source can be efficiently launched, and uneven brightness can be effectively reduced.
If the refractive index is 1.70 or less, (1) introducing a halogen such as chlorine or bromine into the addition polymerizable monomer molecule, (2) introducing an inorganic molecule into the composition, (3) into the composition It can be produced without using a technique such as adding a large amount of an addition polymerizable monomer having a specific structure such as a bisphenol skeleton or a fluorene skeleton. In the case of (1), the burden on the environment is high. In the case of (2), compatibility and moldability as a resin are deteriorated. In the case of (3), the resin viscosity becomes high and handling is difficult. Each has the demerits that it becomes difficult, the curing shrinkage is too large, the transferability is inferior, and the cured resin is too hard and the impact resistance is inferior. The refractive index of the resin layer is preferably 1.58 to 1.70, more preferably 1.60 to 1.70.
When the refractive index is in the range of 1.55 to 1.70, even if the concavo-convex structure is the same as the dimensional shape, the light diffusibility is relatively high compared to the case where the refractive index is low. A diffusion sheet having a high diffusion angle can be realized more easily.
Moreover, the brightness nonuniformity suppression effect of a backlight can be heightened by using the diffusion sheet of embodiment which comprises the resin layer which has a refractive index as mentioned above for a direct type light source unit. Furthermore, when the refractive index of the resin layer having a concavo-convex structure is in the range of 1.55 to 1.70, even if the dimensional shape is the same concavo-convex structure, it is incident obliquely compared to the case where the refractive index is low. Since it becomes easy to raise light directly above, it becomes possible to improve the brightness | luminance of a backlight, for example in an edge light type light source unit.

<Material of resin layer>
The resin constituting the resin layer of the diffusion sheet of the embodiment is a cured product of the photopolymerizable resin composition.
The photopolymerizable resin composition comprises (A) 70-99.9% by mass of an addition polymerizable monomer having at least one terminal ethylenically unsaturated group, and (B) a photopolymerization initiator: 0.1-30% by mass. %.

(A) As the addition polymerizable monomer having at least one terminal ethylenically unsaturated group, a compound having a known (meth) acrylate group or allyl group can be used. For example, nonylphenol acrylate, alkoxylation (1) o-phenylphenol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, β-hydroxypropyl-β ′-(acryloyloxy) propyl phthalate, 1,4-tetramethylene glycol di ( (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, octapropylene glycol di (meth) acrylate, glycerol (meth) acrylate, 2-di (p-hydroxy) Phenyl) propane di (meth) acrylate, glycerol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, polyoxypropyltrimethylolpropane tri (meth) acrylate Polyoxyethyltrimethylolpropane tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane triglycidyl ether tri (meth) acrylate, bisphenol A diglycidyl ether di (Meth) acrylate, diallyl phthalate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, bis (triethylene glycol methacrylate) nonapropylene glycol, bis (tetraethylene glycol methacrylate) polypropylene glycol, bis (triethylene glycol) Methacrylate) polypropylene glycol, bisarylfluorene derivatives, bis (diethyl) (Lene glycol acrylate) polypropylene glycol, compounds containing both ethylene oxide chain and propylene oxide chain in the molecule of bisphenol A (meth) acrylate monomer. A urethanized compound of a polyvalent isocyanate compound such as hexamethylene diisocyanate or tolylene diisocyanate and a hydroxy acrylate compound such as 2-hydroxypropyl (meth) acrylate can also be used.
The urethanized compound in this case is preferably less than 10,000 in terms of polystyrene-reduced number average molecular weight by gel permeation chromatography (GPC).
The above-mentioned (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group may be used alone or in combination of two or more.
When combining 2 or more types, for example, by copolymerizing with methyl methacrylate, these (A) addition polymerizable monomers having at least one terminal ethylenically unsaturated group may be used as the side chain component of the PMMA polymer. For example, alkoxylated phenylphenol acrylate may be used as the side chain component of the PMMA polymer.
From the viewpoint of curing with high sensitivity to irradiated light, those having three or more (meth) acrylate groups are preferable. For example, triacrylate obtained by adding an average of 3 moles of ethylene oxide to trimethylolpropane (Shin-Nakamura Chemical A-TMPT-3EO, product name), pentaerythritol tetraacrylate (Shin-Nakamura Chemical A-TMMT, product name), ethoxy Pentaerythritol tetraacrylate (Shinnakamura Chemical ATM-35E, product name), dipentaerythritol pentaacrylate (Sartomer SR399, product name), ethoxylated (4) pentaerythritol tetraacrylate (Sartomer SR494, product name), etc. Is mentioned.
From the viewpoint of improving the adhesion between the cured resin and the substrate, 2-phenoxyethyl acrylate (Sartomer SR339A, product name), 2-phenoxyethyl methacrylate (Sartomer SR340, product name), alkoxylated tetrahydrofur Furyl acrylate (Sartomer CD611, product name), tetrahydrofurfuryl acrylate (Sartomer SR285, product name), tetrahydrofurfuryl methacrylate (Sartomer SR203, product name) and the like are preferable.
From the viewpoint of imparting flexibility to the cured product after light irradiation, a monomer having a urethane bond or an isocyanuric bond is preferable. For example, pentaerythritol triacrylate hexameric range isocyanate urethane prepolymer (UA306H manufactured by Kyoeisha Chemicals, product name), ε-caprolactone-modified tris (acryloxyethyl) isocyanurate (M-327 manufactured by Toagosei Co., Ltd.), polyol modified Bifunctional urethane acrylate (Kyoeisha Chemical M-1600, product name), bifunctional aliphatic urethane acrylate (Sartomer CN9001, product name), polyester-modified bifunctional urethane acrylate (Sartomer CN981, product name), polyester-modified trifunctional Examples thereof include urethane acrylate (CN929 manufactured by Sartomer, product name).
From the viewpoint of refractive index, 2-phenoxyalkyl (meth) acrylate, nonylphenol-modified (meth) acrylate, isocyanuric-modified (meth) acrylate, tricyclodecane-modified (meth) acrylate, and fluorene-modified (meth) acrylate are preferable. Examples of 2-phenoxyalkyl (meth) acrylate include 2-phenoxyethyl acrylate (Sartomer SR339A, product name), 2-phenoxyethyl methacrylate (Sartomer SR340, product name), and nonylphenol-modified (meth) acrylate. As ethoxylated (4) nonylphenol acrylate (M-113 manufactured by Toa Gosei, product name), 4-nonylphenylheptaethylene glycol dipropylene glycol acrylate (LS-100A manufactured by NOF, product name), isocyanuric modified (meta) Examples of acrylates include isocyanuric acid EO-modified di and triacrylate (M-315, M-313, product name) manufactured by Toagosei, and examples of tricyclodecane-modified (meth) acrylate include tricyclodecane dimethanol dimeta. Examples of Relate (DCP manufactured by Shin-Nakamura Chemical, product name), tricyclodecane dimethanol diacrylate (A-DCP manufactured by Shin-Nakamura Chemical, product name), and fluorene-modified (meth) acrylate include -(2-acryloyloxyethoxy) phenyl] fluorene (Shin-Nakamura Chemical A-BPEF, trade name or Osaka Gas Chemical BPEF-A) and its derivatives (Osaka Gas Chemicals, Ogsol EA-0200, Ogsol EA-0500, Ogsol EA-1000, Ogsol EA-F5003, Ogsol EA-F5503) and the like.
Moreover, the compound shown by the following general formula (X) is also preferable.

Formula (X)

(Wherein R ₁ and R ₂ are each independently H or CH ₃ , and A and B are each independently an alkylene group having 1 to 4 carbon atoms. A1, a2, b1 and b2 is 0 or a positive integer, and the sum of a1, a2, b1, and b2 is 2 to 40.)
Examples of the compound represented by the general formula (X) include 2,2-bis {(4-acryloxypolyethyleneoxy) phenyl} propane or 2,2-bis {(4-methacryloxypolyethyleneoxy) phenyl} propane. Can be mentioned. The polyethyleneoxy group possessed by the compound is monoethyleneoxy group, diethyleneoxy group, triethyleneoxy group, tetraethyleneoxy group, pentaethyleneoxy group, hexaethyleneoxy group, heptaethyleneoxy group, octaethyleneoxy group, nonaethylene It is any group selected from the group consisting of oxy group, decaethyleneoxy group, undecaethyleneoxy group, dodecaethyleneoxy group, tridecaethyleneoxy group, tetradecaethyleneoxy group, and pentadecaethyleneoxy group Compounds are preferred. Further, 2,2-bis {(4-acryloxypolyalkyleneoxy) phenyl} propane or 2,2-bis {(4-methacryloxypolyalkyleneoxy) phenyl} propane can be given. Examples of the polyalkyleneoxy group possessed by the compound include a mixture of an ethyleneoxy group and a propyleneoxy group, an adduct having a block structure or a random structure having an octaethyleneoxy group and a dipropyleneoxy group, and tetraethyleneoxy. An adduct having a block structure of a group and a tetrapropyleneoxy group or an adduct having a random structure, an adduct having a block structure of a pentadecaethyleneoxy group and a dipropyleneoxy group, or an adduct having a random structure is preferable. In the formula, a3, a4, b3 and b4 are 0 or a positive integer, and the total of a3, a4, b3 and b4 is preferably 2 to 30. Among these, ethoxylated bisphenol A dimethacrylate (manufactured by Shin-Nakamura Chemical, BPE-100, BPE-200, BPE-500, BPE-900, BPE-1300N, product names), ethoxylated bisphenol A diacrylate (Shin Nakamura Chemical) ABE-300, A-BPE-10, A-BPE-20, A-BPE-30, A-BPE-4, product name), propoxylated bisphenol A diacrylate (manufactured by Shin-Nakamura Chemical, A-BPP- 3, product name), propoxylated ethoxylated bisphenol A diacrylate (manufactured by Shin-Nakamura Chemical Co., A-B1206PE, product name) and 2,2-bis {(4-methacryloxypentaethyleneoxy) phenyl} propane are most preferred.
Among these, a compound represented by the following general formula (I) is preferred from the viewpoint of refractive index, and a compound represented by the following general formula (II) is most preferred.

Formula (I)

(In the formula, R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.)

Formula (II)

(In the formula, R represents a hydrogen atom or a methyl group, A independently represents an alkylene group having 1 to 4 carbon atoms, and n represents an integer of 1 to 3).

Examples of compounds represented by general formula (I) include alkylated (1) o-phenylphenol (meth) acrylate, alkylated (2) o-phenylphenol (meth) acrylate, alkylated (3) o-phenyl. Phenol (meth) acrylate, alkylated (4) o-phenylphenol (meth) acrylate, alkoxylated (1) o-phenylphenol (meth) acrylate, alkoxylated (2) o-phenylphenol (meth) acrylate, alkoxylated (3) o-phenylphenol (meth) acrylate, alkoxylation (4) o-phenylphenol (meth) acrylate, alkoxylation (5) o-phenylphenol (meth) acrylate, alkoxylation (6) o-phenylphenol ( (Meth) acrylate, alkenylation 1) o-phenylphenol (meth) acrylate, alkylation (1) alkoxylation (1) o-phenylphenol (meth) acrylate, alkylation (2) alkoxylation (2) o-phenylphenol (meth) acrylate, alkyl (2) alkoxylation (3) o-phenylphenol (meth) acrylate. Among these, alkoxylated (1) o-phenylphenol acrylate is preferable from the viewpoint of refractive index, and ethoxylated (1) o-phenylphenol acrylate (for example, product name A-LEN-10, manufactured by Shin-Nakamura Chemical) is particularly preferable. .
Further, in these compounds, a compound in which a residue is bonded to the meta position or para position in place of the ortho position of the biphenyl group, for example, ethoxylated (1) m-phenylphenol acrylate, ethoxylated (1) p-phenylphenol Acrylates are also preferred.

Examples of the compound represented by the general formula (II) include methoxylated (1) o-phenylphenol (meth) acrylate, methoxylated (2) o-phenylphenol (meth) acrylate, and methoxylated (3) o-phenyl. Phenol (meth) acrylate, ethoxylated (1) o-phenylphenol (meth) acrylate, ethoxylated (2) o-phenylphenol (meth) acrylate, ethoxylated (3) o-phenylphenol (meth) acrylate, propoxylated (1) o-phenylphenol (meth) acrylate, propoxylated (2) o-phenylphenol (meth) acrylate, propoxylated (3) o-phenylphenol (meth) acrylate, butoxylated (1) o-phenylphenol ( (Meth) acrylate, butoxylation ( ) O-phenylphenol (meth) acrylate, butoxy reduction (3) o-phenylphenol (meth) acrylate.
Among these, ethoxylated (1) o-phenylphenol acrylate (for example, product name A-LEN-10, manufactured by Shin-Nakamura Chemical Co., Ltd.) is preferable.

The content ratio of the compound represented by the general formula (I) or (II) in the addition polymerizable monomer (A) having at least one terminal ethylenically unsaturated group is 50 to 95% by mass. preferable.
From the viewpoint of increasing the refractive index of the resin layer, 50% by mass or more is preferable, and from the viewpoint of preventing a decrease in photocurability, the content is preferably 95% by mass or less.

As the above-mentioned (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group, in addition to the compound represented by the above general formula (I) or (II), a known (meth) acrylate group or allyl Compounds having groups can be used.
For example, nonylphenol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, β-hydroxypropyl-β ′-(acryloyloxy) propyl phthalate, 1,4-tetramethylene glycol di (meth) acrylate, 1,6-hexanediol di (Meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, octapropylene glycol di (meth) acrylate, glycerol (meth) acrylate, 2-di (p-hydroxyphenyl) propane di (meth) acrylate, glycerol tri ( (Meth) acrylate, trimethylolpropane tri (meth) acrylate, polyoxypropyltrimethylolpropane tri (meth) acrylate, polyoxyethyltrimethylolpropane tri (meth) Acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane triglycidyl ether tri (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, diallyl phthalate, polyethylene glycol di ( (Meth) acrylate, polypropylene glycol di (meth) acrylate, bis (triethylene glycol methacrylate) nonapropylene glycol, bis (tetraethylene glycol methacrylate) polypropylene glycol, bis (triethylene glycol methacrylate) polypropylene glycol, bis (diethylene glycol acrylate) polypropylene glycol , Bisphenol A-based (meth) ac Examples thereof include compounds containing both an ethylene oxide chain and a propylene oxide chain in the molecule of the acrylate monomer.

A urethanized compound of a polyvalent isocyanate compound such as hexamethylene diisocyanate or tolylene diisocyanate and a hydroxy acrylate compound such as 2-hydroxypropyl (meth) acrylate can also be used.
The urethanized compound in this case is preferably less than 10,000 in terms of polystyrene-reduced number average molecular weight by gel permeation chromatography (GPC).

  The above-mentioned (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group may be used alone or in combination of two or more.

  The content of the (A) addition polymerizable monomer in the photopolymerizable resin composition is 70% by mass or more and 99.9% by mass or less based on the total mass of the photopolymerizable resin composition. Preferably they are 75 mass% or more and 95 mass% or less. From the viewpoint of sufficient curing, the content is 70% by mass or more, and is 99.9% by mass or less in consideration of blending an initiator component, other polymerization inhibitors, dyes, and the like.

Examples of the photopolymerization initiator (B) in the photopolymerizable resin composition include benzyl dimethyl ketal, benzyl diethyl ketal, benzyl dipropyl ketal, benzyl diphenyl ketal, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, Benzoin phenyl ether, thioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diisopropylthioxanthone, 2-fluorothioxanthone, 4-fluorothioxanthone, 2-chloro Thioxanthone, 4-chlorothioxanthone, 1-chloro-4-propoxythioxanthone, benzophenone, 4,4'-bis (dimethylamino) benzofe Aromatic ketones such as non [Michler's ketone], 4,4′-bis (diethylamino) benzophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one , Biimidazole compounds such as 2- (o-chlorophenyl) -4,5-diphenylimidazolyl dimer, acridines such as 9-phenylacridine, α, α-dimethoxy-α-morpholino-methylthiophenylacetophenone, 2,4 , 6-trimethylbenzoyldiphenylphosphine oxide, phenylglycine, N-phenylglycine, 1-phenyl-1,2-propanedione-2-O-benzoyloxime, ethyl 2,3-dioxo-3-phenylpropionate 2- (O-benzoylcarbonyl) -oxime Oxime esters such as p-dimethylaminobenzoic acid, p-diethylaminobenzoic acid, and p-diisopropylaminobenzoic acid, and esterified products thereof with these alcohols, p-hydroxybenzoic acid ester, 3-mercapto-1,2 Triazoles such as 1,4-triazole, tetrazoles, N-phenylglycine, N-phenyl-N-phenylglycine, N-phenylglycine such as N-ethyl-N-phenylglycine, and 1-phenyl-3- Styryl-5-phenyl-pyrazoline, 1- (4-tert-butyl-phenyl) -3-styryl-5
-Phenyl-pyrazoline, 1-phenyl-3- (4-tert-butyl-styryl) -5
And pyrazolines such as-(4-tert-butyl-phenyl) -pyrazoline.
Among these, 2-hydroxy-2-methyl-1-phenyl-propan-1-one (for example, product name DAROCURE 1173, manufactured by Ciba Specialty Chemical) is preferable.

The content of the photopolymerization initiator (B) in the photopolymerizable resin composition is 0.1% by mass or more and 30% by mass or less, preferably 1% by mass based on the total mass of the photopolymerizable resin composition. It is 20 mass% or less.
When the content of (B) is 0.1% by mass or more, sufficient photocuring sensitivity can be obtained, and when it is 30% by mass or less, storage stability as a liquid resin before photocuring is obtained. .

In order to improve thermal stability and storage stability, it is preferable to contain a radical polymerization inhibitor in the photopolymerizable resin composition.
Examples of such radical polymerization inhibitors include p-methoxyphenol, hydroquinone, pyrogallol, naphthylamine, t-butylcatechol, cuprous chloride, 2,6-di-t-butyl-p-cresol, 2,2 Examples include '-methylenebis (4-ethyl-6-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), and the like.
The content of the radical polymerization inhibitor is preferably 0.001% by mass or more and 1% by mass or less based on the total mass of the photopolymerizable resin composition.

(Diffusion sheet characteristics)
In the diffusion sheet of the embodiment, it is preferable that the diffusion angle is periodically changed along a predetermined direction in the plane when light rays are incident on the diffusion sheet surface vertically.
Thereby, since the diffusibility can be changed according to the illuminance distribution in the sheet surface, the effect that the luminance unevenness can be reduced more uniformly is obtained.

The diffusion sheet of the embodiment constitutes a light source unit to be described later by combining with a predetermined light source.
Here, in order to explain the optical function of the diffusion sheet, the relationship between the diffusion sheet and the light source of the embodiment in the light source unit will be described.
FIGS. B2 (a) and (b) show the projection area of the light source and the projection area between the light sources when the light sources B101 and 102 are arranged facing the diffusion sheet B15, respectively.
When configuring the light source unit, other optical sheets having other predetermined functions can be arranged between the diffusion sheet B15 and the light sources B101 and 102, but in FIGS. B2 (a) and (b) Is omitted.

A plurality (at least two) of light sources are arranged.
As the light source, a line light source such as a cold cathode fluorescent lamp (CCFL) B101 as shown in FIG. B2 (a), or a point light source such as an LED (light emitting diode) B102 or a laser as shown in FIG. B2 (b). Can be used.
In FIGS. B2 (a) and (b), symbol B103 indicates a projection area immediately above the light source, and symbol B104 indicates a projection area between the light sources.
The projection area directly above the light source requires high diffusivity, and the projection area between the light sources does not require high diffusivity. By dividing the area in this way, the diffusion angle can be designed reliably. .
FIGS. B2 (a) and (b) show an example in which the entire area is divided into a projection area B103 immediately above the light source and a projection area B104 between the light sources. There may be an area other than the projection area B103 and the projection area B104 between the light sources, for example, end portions such as four corners.
Further, the projection area B104 between the light sources may not be adjacent to the projection area B103 immediately above the light source, and is an area located in the middle of the adjacent light sources (for example, a broken line in FIGS. B2 (a) and (b)). An intermediate region of the light source disposed along the light source).

The “diffusion angle” refers to an angle (FWHM: Full Width Half Maximum) that is twice the angle at which the transmitted light intensity attenuates to half of the peak intensity (half-value angle).
FIG. B3 (a) shows an explanatory diagram of the diffusion angle. The horizontal axis represents the outgoing angle of the transmitted light, and the vertical axis represents the transmitted light intensity (relative value).

This diffusion angle is, for example, Gotonometric Radiometers Real-Time manufactured by Photon Corporation.
It can be obtained by measuring the angular distribution of transmitted light intensity with respect to light incident from the uneven surface side, using the Far-Field Angular Profile Model LD8900 (hereinafter referred to as LD8900) from the normal direction of the uneven surface of the diffusion sheet B15.
Here, in FIG. B3 (b), the transmitted light intensity is schematically shown when light is incident on the uneven surface side of the diffusion sheet B15 from the normal direction.

In addition, as the diffusion sheet of the embodiment, both an isotropic sheet capable of obtaining substantially the same diffusion angle regardless of the measurement direction and an anisotropic sheet having a different diffusion angle depending on the measurement direction can be used.
An anisotropic sheet is, for example, a sheet having different diffusion angles when the diffusion angles are measured in two orthogonal directions.

As described above, the diffusion sheet of the embodiment preferably has a diffusion angle that periodically changes along a predetermined direction in the sheet surface.
Here, “cyclically changing” means that the repeated patterns are compared with each other, and the peak value corresponding to the same repetition and the displacement from the start point of the period giving the peak value are the average value of all the repeated patterns. Within a range of ± 15% (preferably within 10%, more preferably within 5%), the bottom value and the displacement from the start point of the cycle giving the bottom value are ± 15% of the average value of all repeated patterns Within the range (preferably within 10%, more preferably within 5%), it corresponds to a periodically changing one.
The direction showing the periodicity may be at least one in the diffusion sheet surface, and can be specified by creating a distribution of diffusion angles on the diffusion sheet surface.
In the embodiment, the diffusion angle of a plurality of repeated peak values is preferably such that the difference in the diffusion angles of all the measured peak values is within 5 °, more preferably within 3 °, and within 2 °. Most preferably it is. The same applies to the bottom value.

The diffusion capability of such a diffusion sheet is represented by a diffusion angle distribution diagram in which the horizontal axis represents the relative position in the sheet surface in the predetermined direction, and the vertical axis represents the diffusion angle at the relative position in the sheet surface. be able to.
FIG. B4 is a diagram illustrating one cycle of the distribution of the diffusion angle with respect to the relative position in the surface of the diffusion sheet in the example of the diffusion sheet described above.
In this diffusion sheet, when a light beam is incident perpendicularly to the sheet surface, the diffusion angle of the emitted light periodically changes along a predetermined direction in the sheet surface.
In the diffusion angle distribution diagram shown in FIG. B4, the horizontal position represents the relative position within the sheet surface in a predetermined direction within the diffusion sheet surface, and the vertical axis represents the diffusion angle at the relative position within the sheet surface.

The diffusion sheet of the embodiment preferably includes a plurality of peak points where the diffusion angle indicates a peak value and a plurality of bottom points where the diffusion angle indicates a bottom value (in FIG. B4, there is one peak point and a bottom point). Two are shown).
The peak value refers to the highest diffusion angle value in one cycle of the diffusion angle distribution, and the bottom value refers to the lowest diffusion angle value in one cycle of the diffusion angle distribution.
In the diffusion sheet of the embodiment, in such a diffusion angle distribution diagram, the arithmetic average value of the peak value and the bottom value indicated by the adjacent peak point and the bottom point is between the adjacent peak point and the bottom point. It is preferably larger than the arithmetic average value of the diffusion angles at all points distributed in the range.
The “all points” described here mean all the measurement points.

The change in the diffusion angle is the arithmetic average value of the diffusion angle at all points where the arithmetic average value of the peak value and the bottom value indicated by the adjacent peak point and the bottom point is distributed between the adjacent peak point and the bottom point. If it is larger, it does not have to be strictly linear, curved, or stepped, but may vary from linear, curved, stepped, or a mixture of straight and curved due to variations in measurement of diffusion angle, etc. There may be.
When transitioning from the region directly above the light source on the diffusion sheet to the region between the light sources, the light incident angle with respect to that position increases linearly.

Considering that the intensity of light reflected downward from the diffusion sheet (that is, the light source side) and light transmitted in an oblique direction with respect to the normal direction of the diffusion sheet increases as the incident light angle increases. The amount of light to be diffused is not linear as it transitions from the region directly above the light source to the region between the light sources, and it is preferable that the amount of light attenuate more than that.
That is, the diffusion sheet in which the arithmetic average value of the peak value and the bottom value indicated by the adjacent peak point and the bottom point is larger than the arithmetic average value of the diffusion angles at all points distributed between the adjacent peak point and the bottom point. If so, it is possible to reduce luminance unevenness in accordance with attenuation of light to be diffused.
In FIG. B5 (a) to FIG. B5 (f), the horizontal axis is the relative position on the surface of the diffusion sheet, and the vertical axis is the diffusion angle (FWHM). The example of the diffusion angle distribution figure of the diffusion sheet which has changed to the mixed shape is shown.

In general, it is preferable to arrange a region having a relatively high diffusion angle immediately above the light source, but when the diffusion angle is extremely high as a whole, the illuminance immediately above the light source A region having a relatively low diffusion angle in the diffusion sheet may be disposed in a region having a high value.
Moreover, it is preferable that the diffusion angle between each area | region changes smoothly.
In particular, it is preferable that there is a shape including a plurality of continuous peak values in the high diffusion angle region from the viewpoint of reducing luminance unevenness, and the shape is a straight line or a downwardly convex curve or a straight line and a downwardly convex curve. A mixed shape is preferable (FIGS. B5 (d) and (f)). Such a pattern is particularly effective when the light source is a line light source.

Further, there is a bottom value of the diffusion angle, and the diffusion angle distribution in the low diffusion angle region including the bottom value is preferably a downward convex curve with the bottom value being the minimum value from the viewpoint of reducing luminance unevenness. (FIG. B5 (a)-(d)).
FIG. B5 (c) shows a first section in which the distribution of the diffusion angle includes the peak value and has an upward convex curve shape, and the distribution of the diffusion angle includes the bottom value and has a downward convex curve shape. Such a pattern is particularly effective when the light source is a point light source. For example, when an LED (light emitting diode) is used as the point light source, the diffusion angle in the diffusion sheet of the embodiment can be designed with respect to the illuminance distribution regardless of the light emission angle. Specifically, assuming that the illuminance is distributed in a relative numerical step, there is a case where the diffusion angle is designed corresponding to the numerical value.

Here, the “high diffusion angle region” is an angle region larger than the arithmetic average value of the maximum value of the peak value and the minimum value of the bottom value, and the “low diffusion angle region” is the maximum value and the bottom value of the peak value. The angle region is smaller than the arithmetic average value of the minimum value of.
The arithmetic average value of the peak value and the bottom value is calculated using a distribution of diffusion angles based on the above definition.
In one cycle, the peak value and the bottom value are not limited to one, and a plurality of the same values may exist.
Further, the diffusion angle at all points distributed between adjacent peak points and bottom points refers to the diffusion angle existing in the broken line section of FIG. B4.
That is, when there are a plurality of peak points, it means the diffusion angle existing at all points in the section between the position corresponding to the adjacent bottom point and the position corresponding to the peak point.

B6 to B8 are diagrams illustrating examples of arrangement of the high diffusion angle region and the low diffusion angle region of the diffusion sheet of the embodiment.
B6 and B7 show that the high diffusion angle region B301 and the low diffusion angle region B302 periodically exist in the x-axis direction within the diffusion sheet surface, that is, the diffusion angles are as shown in FIGS. ) As shown in FIG.
The patterns shown in FIGS. B6 and B7 are preferably used for a line light source, but may be used for a point light source.

FIG. B8 is a diagram in which a high diffusion angle region B303 and a low diffusion angle region B304 periodically exist in the x-axis direction and the y-axis direction in the sheet surface.
Again, in the cross section of the diffusion sheet in the x-axis or y-axis direction, the diffusion angle changes as shown in FIGS.
The pattern as shown in FIG. B8 is preferably used for a point light source, but may be used for a line light source.

A diffusion sheet having a concavo-convex structure on the surface and whose diffusion angle varies depending on the position on the surface can be produced as follows.
First, a sub-master mold in which a speckle pattern is formed so that a diffusion angle changes depending on a position by irradiating a photosensitive material or a photoresist with a laser beam through a lens or a mask in advance by interference exposure.
It is possible to control the range of the diffusion angle by changing the distance and size between the members constituting the laser irradiation system and adjusting the size, shape and direction of the speckle pattern, and record the uneven structure with different diffusion angles. it can.

The range of the diffusion angle is formed and controlled by the concavo-convex structure, and generally depends on the average size and shape of the speckle.
If speckle is small, the angle range is wide.
Moreover, the unit structure of the unevenness is not limited to an isotropic one, and an anisotropic one can be formed, or an uneven structure in which both are combined can be formed.
If the speckle is an oval in the horizontal direction, the shape of the angular distribution is an oval in the vertical direction.
In this way, a sub-master type in which the diffusion angle changes depending on the position is manufactured.
A metal is deposited on the sub-master mold by a method such as electroforming, and a speckle pattern is transferred to the metal to produce a master mold.
The speckle pattern is transferred to the resin layer by shaping the uncured resin layer made of the above-described photopolymerizable resin composition with ultraviolet rays using the master mold.
A detailed manufacturing method of this diffusion sheet in which the diffusion angle is changed depending on the position is disclosed in JP-T-2003-525472 (International Publication No. 01/065469).
Specifically, a light source, a mask provided with an aperture of variable size and shape provided in the optical path of light projected from the light source, a plate for recording a diffusion pattern generated by the light projected from the light source, Using a diffuser plate that diffuses light disposed between the mask and the plate, and a blocker provided between the diffuser plate and the plate to block part of the light, the size and shape of the mask opening and blocker, It is produced by changing the diffusion degree of the diffusion plate and the distance between the constituent members.

For example, the following method is mentioned.
(1) By making the opening shape of the mask vertically long, the shape of the bottom surface of the convex portion recorded on the plate is made into a horizontally long ellipse and exhibits a vertically long elliptical diffusing ability (diffusing angles in two orthogonal directions are different). Form a region.
(2) By making the opening shape of the mask square, the shape of the bottom surface of the convex portion recorded on the plate is isotropic, and isotropic diffusion ability (the diffusion angle is the same in all directions) Form.
When the periodic patterns are formed by combining the patterns (1) and (2), the diffusion sheet of the embodiment, that is, the diffusion sheet whose diffusion angle periodically changes in the plane can be manufactured.

The uneven height of the surface structure of the diffusion sheet can be determined from the pitch, aspect ratio, surface roughness, etc. of the cross-sectional shape of the diffusion sheet observed with a scanning electron microscope, for example.
Further, the pitch, aspect ratio, surface roughness, and the like can also be read from an observation image of the diffusion sheet surface by a laser confocal microscope.
For example, as the pitch is shorter, the aspect ratio is larger, or the surface roughness is larger, it can be considered that the unevenness height is higher.

[Light source unit]
The light source unit of the embodiment includes two or more light sources and the above-described diffusion sheet disposed to face the light sources.
B9 (a), (b), FIG. B10 (a), and (b) are schematic configuration diagrams of the light source unit of the embodiment.
The light source unit of the embodiment uses a plurality of light sources. As the light source, a linear light source B11 such as a cold cathode tube (CCFL) as shown in FIG. B9, an LED (light emitting diode) as shown in FIG. A point light source B12 such as a laser can be used.
In this case, the light sources B11 and 12 are arranged directly below the light incident surface and the light outgoing surface of the diffusion sheet B15.
The light source unit basically includes a light source (a linear light source B11 or a point light source B12) and a diffusion sheet B15 according to the embodiment disposed to face the light sources B11 and 12 (see FIG. B9 (a), FIG. B10 (a) reference).
Moreover, it is preferable that a reflection sheet B13 having a function of reflecting light is disposed on the back side of the line light source B11 and the point light source B12, that is, on the side opposite to the diffusion sheet arrangement side.

Further, if the optical unit has the above-described configuration, a predetermined optical sheet, a diffusion plate containing a diffusing agent (reference numeral 14 in common) and the like may be further disposed. For example, the light source B11 , 12 and the diffusion sheet B15, a diffusion plate or a predetermined optical sheet B14 can be provided (FIG. B9 (b), FIG. B10 (b)).
As the diffusing plate B14, a conventionally known one can be used as long as it has a function of diffusing light. For example, polystyrene, acrylic resin, polycarbonate, cycloolefin polymer, or the like added with an organic polymer or inorganic fine particles having an effect of diffusing light can be used. These diffusers have the effect of diffusing light and making the light from the lower light source uniform. Moreover, the uneven | corrugated shape may be formed in the said diffusion plate on the surface.
A diffusion plate in which two or more components are mixed and stretched to form a sheet can also be used.

As the reflection sheet B13, a conventionally known material can be used as long as it has a function of reflecting light.
For example, a resin such as polyester or polycarbonate is foamed and fine air particles are put inside to form a sheet, a sheet formed by mixing two or more resins, and a resin layer with a different refractive index is laminated. Any of the sheets can be used.
In addition, the reflective sheet B13 may have an uneven shape on the surface.
As these, those having inorganic fine particles added to the surface can be used as necessary.

In the light source unit of the embodiment, when a diffusion sheet whose diffusion angle periodically changes along a predetermined direction in the above-described plane is used, the period of the diffusion angle distribution of the diffusion sheet and the light incident surface of the diffusion sheet It is preferable that the period of the illuminance distribution at is substantially equal.
As described above, the period of the diffusion angle distribution controls the distance, size, speckle pattern, shape, and direction between the members constituting the laser irradiation system when recording the uneven structure on the surface in the manufacturing process of the diffusion sheet. Can be adjusted.
The illuminance distribution on the light incident surface of the diffusion sheet B15 can be measured by, for example, EZCONTRASTXL88 manufactured by ELDIM. Specifically, in the light source unit provided with the diffusion sheet B15, the omnidirectional luminance distribution is measured by setting the focal point of the apparatus at the position where the light incident surface of the diffusion sheet is located, excluding the diffusion sheet, and integrating from the result Measurement is performed by repeating the process of obtaining an integrated intensity in the in-plane measurement target range.
B11 (a) and (b) are schematic perspective views of a specific configuration example of the light source unit of the embodiment.
In the light source unit shown in FIGS. B11 (a) and (b), the diffusion sheet B15 has a direction in which the diffusion angles are periodically distributed in the plane, and the diffusion angles are periodically distributed. It arrange | positions so that the direction orthogonal to a longitudinal direction may correspond.
Note that FIG. B11 (b) has a configuration in which a predetermined optical sheet B14 is added to the configuration of FIG. B11 (a).

FIG. B12 is a diagram showing the relationship between the relative position of the light source and the diffusion angle distribution period of the diffusion sheet in the light source unit.
In FIGS. B11 (a) and (b), since the period of the illuminance distribution on the light incident surface of the diffusion sheet is equal to the interval between the light sources, the diffusion angle distribution period in the diffusion sheet surface is made approximately equal to the light source interval. Thus, the period of the illuminance distribution can be made substantially equal to the period of the diffusion angle distribution described above.
In the illuminance distribution on the light incident surface of the diffusion sheet, when the illuminance in the region directly above the light source is high, it is preferable to dispose a high diffusion angle region of the diffusion sheet from the viewpoint of eliminating luminance unevenness.
FIG. B12 shows an example of the diffusion angle distribution designed to correspond to the illuminance distribution on the light incident surface of the diffusion sheet.
Further, the difference in diffusion angle, uneven height in the projection area between the light source B11, 12 and the projection area between the light sources B11, 12 and how the diffusion angle / concave height changes depending on the position in the diffusion sheet surface, In order to make the luminance uniform, it can be appropriately adjusted.

Hereinafter, a specific configuration example of the light source unit of the embodiment will be described.
For example, the arrangement shown in FIGS. B13 (a) to B13 (c) can be adopted as the configuration of the light source unit.
In these, CCFL which is line light source B11 is illustrated as a light source, but the light source may be a point light source B12 such as an LED as shown in FIG. B14, for example.

FIG. B13 (a) shows the configuration of the light source unit shown in FIG. B9 (b) described above, between the diffusion plate B14 disposed directly above the light source B11 and the diffusion sheet B15 with reference to the vertical direction in the drawing. 1 shows a light source unit in which a surface-shaped diffusion sheet B16 having a fine concavo-convex structure formed thereon is disposed, and the surface-shaped diffusion sheet B16 is disposed immediately above the diffusion sheet B15. Here, as the surface-shaped diffusion sheet B16, a sheet in which spherical beads made of an acrylic resin are coated on a sheet of polyester resin, triacetyl cellulose, polycarbonate, or the like can be used.
Further, as the surface-shaped diffusion sheet B16, a sheet in which a fine concavo-convex structure by an ultraviolet curable resin is transferred onto a sheet of polyester resin, triacetyl cellulose, polycarbonate, or the like can be used.
Such a surface shaping type diffusion sheet B16 has a function of condensing the light diffused by the diffusion plate B14, together with the effect of diffusing and uniformizing the light. By using these surface-shaped diffusion sheet B16 and diffusion sheet B15 in combination, luminance unevenness can be reduced, and the light source unit can be made thinner and the number of light sources can be reduced.

FIG. B13 (b) shows an array-like prism arrangement structure above the diffusion plate B14 and the diffusion sheet B15 arranged immediately above the light source B11 with reference to the vertical direction in the drawing in the configuration shown in FIG. B9 (b). A light source unit in which an optical sheet (hereinafter also referred to as “prism sheet”) 17 having a surface and a surface-shaped diffusion sheet B16 on which the fine uneven structure described above is formed is arranged in this order. .
FIG. B13 (c) shows a fine concavo-convex structure in the configuration shown in FIG. B9 (b) above the diffusion plate B14 and the diffusion sheet B15 arranged immediately above the light source B11 with reference to the vertical direction in the drawing. Shows a light source unit in which a surface-shaped diffusion sheet B16 formed on the surface and a reflective polarizing sheet B18 are arranged.
As the prism sheet B17, it is possible to use an optical sheet in which prism rows having a substantially triangular shape, a substantially trapezoidal shape, and a substantially elliptical shape are arranged in an array on the surface.
A shape obtained by rounding the apex of the cross-sectional shape can be preferably used from the viewpoint of improving scratch resistance. These prism sheets B17 can be used in a form in which a prism array made of an ultraviolet curable resin is transferred onto a base material sheet such as polyester resin, triacetyl cellulose, or polycarbonate. Since such a prism sheet B17 exhibits retroreflectivity, it has a function of collecting incident light to the front. By using this prism sheet in combination with the diffusion sheet of the embodiment, it is possible to reduce luminance unevenness, reduce the thickness of the light source unit, and reduce the number of light sources.

FIG. B14 (a) shows a surface having a fine concavo-convex structure above the diffusion plate B14 and the diffusion sheet B15 arranged immediately above the light source B12 with reference to the vertical direction in the drawing in the configuration shown in FIG. B10 (b). 2 shows a light source unit in which two surface-shaped diffusion sheets B16 formed in the above are arranged and a reflective polarizing sheet B18 is arranged in this order.
FIG. B14 (b) shows the configuration shown in FIG. B10 (b), in which a prism sheet B17 is disposed above the diffusion plate B14 and the diffusion sheet B15 disposed immediately above the light source B12 with reference to the vertical direction in the drawing. Further, a light source unit in which a reflective polarizing sheet B18 is arranged in this order is shown.
As the reflective polarizing sheet B18, a sheet having a function of separating linearly polarized light from natural light or polarized light can be used.
As a sheet | seat which isolate | separates the said linearly polarized light, the film etc. which permeate | transmit one of the linearly polarized light orthogonal to an axial direction, and reflect the other are mentioned, for example.
Specifically, as the reflective polarizing sheet B18, a resin (polycarbonate, acrylic resin, polyester resin, etc.) having a large birefringence retardation and a resin (cycloolefin polymer, etc.) having a small birefringence retardation are alternately used. A sheet obtained by laminating and uniaxially stretching, a sheet having a structure in which several hundred layers of birefringent polyester resin are laminated (trade name DBEF, manufactured by 3M Co., Ltd.), and the like can be used.

In addition, as the configuration of the light source unit, for example, the arrangement configuration shown in FIGS. B15 and B16 can be adopted. In the following, the arrangement configuration is shown with reference to the vertical direction in the drawing, as in the example described above.
FIG. B15 (a) shows a configuration shown in FIG. B9 (a), in which a diffusion plate B14 is disposed between the light source B11 and the diffusion sheet B15, and a surface-shaped diffusion sheet B16 is disposed immediately above the diffusion sheet B15. A light source unit is shown.
Moreover, FIG. B15 (b) shows the light source unit which arrange | positions in order of the diffusion plate B14 and the surface shaping type | mold diffusion sheet B16 above the diffusion sheet B15 in the structure shown to FIG. B9 (a).
FIG. B15 (c) shows a configuration shown in FIG. B9 (a), in which a diffusion plate B14 is disposed between the light source B11 and the diffusion sheet B15, and further above the diffusion sheet B15, a prism sheet B17 and a reflective polarizing sheet B18. The light source units arranged in this order are shown.
FIG. B15 (d) shows a configuration in which the diffusion plate B14 is disposed between the light source B11 and the diffusion sheet B15 in the configuration shown in FIG. B9 (a), and the prism array direction of the prism sheet B17 is disposed above the diffusion sheet B15. A light source unit in which two sheets are arranged so as to be orthogonal to each other and a surface-shaped diffusion sheet B16 is further disposed thereon is shown.

  FIG. B16 (a) shows a configuration shown in FIG. B9 (a), in which a diffusion plate B14 is disposed between the light source B11 and the diffusion sheet B15, and further, a surface-shaped diffusion sheet B16 and a prism are disposed above the diffusion sheet B15. A light source unit in which a sheet B17 and a reflective polarizing sheet B18 are arranged in this order is shown. Further, FIG. B16 (b) shows that in the configuration shown in FIG. B9 (a), the diffusion plate B14, the surface shaping type diffusion sheet B16, the prism sheet B17, and the reflection type polarizing sheet B18 are disposed above the diffusion sheet B15. The light source units arranged in order are shown.

[Liquid Crystal Display]
The liquid crystal display device according to the embodiment includes a predetermined display unit and the light source unit according to the embodiment described above.
For example, a liquid crystal display panel having a liquid crystal layer between two polarizing plates is provided above the light source unit of the embodiment as shown in FIG. B10 (b).

  The diffusion sheet and light source unit of the first invention of the specification have industrial applicability as a diffusion sheet and light source unit for liquid crystal display devices.

  Next, a description will be given of a second invention of the present specification relating to a light guide plate that can be suitably used in the present invention.

  The second specification relates to a light guide member, for example, a so-called edge light type surface light source device and a light guide plate that can be used in various illumination devices.

In the liquid crystal display device, since the liquid crystal display panel itself does not emit light, a surface light source device is required. As the surface light source device, two types are used: a direct type surface light source device in which the light source is installed on the back surface of the liquid crystal display panel, and an edge light type surface light source device in which the light source is installed on the side surface of the liquid crystal display panel. When importance is attached to thinning of a display device, an edge light type surface light source device suitable for thinning is often used.
Such an edge light type surface light source device generally includes a light guide plate that emits light from the light source to the liquid crystal display panel side, and an LED (light emitting diode) or CCFL (cold cathode) disposed on the side of the light guide plate. A light source such as a tube) and a prism sheet that directs light emitted from the light guide plate toward the liquid crystal display panel.
The light guide plate generally has a first surface (hereinafter also referred to as “light-emitting surface”), a second surface (hereinafter also referred to as “opposing surface”) facing the first surface, and the light-emitting surface facing the first surface. Light having at least one light incident surface sandwiched between surfaces, light that is incident from the side (light incident surface) is repeatedly reflected inside the plate and guided, and the light guided is provided on the opposing surface The light is emitted from the light emission surface to the liquid crystal display panel side by the emission mechanism.

By the way, when such a light guide plate is used in combination with a plurality of point light sources, a uniform brightness can be obtained at the center of the light exit surface (a part away from the point light source), but near the light entrance surface close to the point light source. In this area, the partial area directly facing the portion between the point light source and the point light source is dark, whereas an extremely bright so-called hot spot appears in the partial area directly facing the point light source, resulting in luminance unevenness. There are drawbacks.
Therefore, in the surface light source device using a plurality of point light sources as the light source, there is a problem that substantially only the center portion of the light exit surface of the light guide plate can be used.
As a method for preventing such luminance unevenness, an optical structure for diffusing incident light on the light incident surface (hereinafter also referred to as “diffusion structure”) has been studied.

  For example, Japanese Patent Laid-Open No. 2002-169034 discloses a light guide plate provided with a trapezoidal concavo-convex structure in which a symmetrical triangular shape is formed on a light incident surface. A light guide plate is disclosed in which a light-receiving surface is provided with a recess having a substantially square opening and an arcuate corner at the bottom.

  Furthermore, Japanese Patent Laid-Open No. 2006-49286 discloses a light guide plate in which a knurled cut is made on the opposing surface and a periodic fine cut such as a lenticular shape is made on the light incident surface. The gazette discloses a light guide plate in which an anisotropic light diffusing adhesive layer comprising an adhesive and a needle-like filler is provided on the light incident surface.

By the way, in a CRT display device that scans a phosphor surface with an electron gun and displays an image, each pixel on the image display surface emits light only for an instant for one frame, whereas in a liquid crystal display device, each pixel is lit by an illumination device. The light is emitted all the while. Therefore, in the liquid crystal display device, a decrease in contrast and blurring of moving images occur due to the afterglow characteristics of human eyes. As a countermeasure, the light exit surface portion of the light guide plate is divided into a plurality of parts, and only a part of the light exit surface portion of the light guide plate is caused to emit light by lighting only a part of the plurality of light sources. A technique for performing area control so as not to emit light, or a technique for adjusting the amount of light in each section (hereinafter referred to as “local dimming”) is known. In addition to improving the contrast of the display image described above, local dimming reduces power consumption and reduces the phenomenon (crosstalk) in which the right eye image and the left eye image can be seen simultaneously when displaying a 3D image. Is also a useful technique that can be used.
In the liquid crystal display device using the edge light type surface illumination device, in order to perform the above-mentioned local dimming, a plurality of light sources arranged in the vicinity of the light incident surface of the light guide plate are divided into two or more sections (for example, “upper half” ”And“ lower half ”), and only the necessary sections are lit. At this time, since the light emitted from the light source is diffusive, it is totally reflected between the light exit surface and the opposing surface in accordance with the critical angle of the material of the light guide plate in the sections other than the section where the light exit surface is desired to emit light. Since the light spreads in the range where the light source continues, there is a problem that the section adjacent to the section where the light source is turned on also emits light.
Thus, as one form for realizing local dimming, there has been proposed an illuminating device in which the light emitting area of the light exit surface is divided into a plurality of strip-shaped areas (see, for example, JP-A-2001-210122). Further, it is proposed to provide a convex part on the light incident surface of the light guide plate and arrange a light source on the top, and to arrange a lenticular lens on the light incident surface of the light guide plate and to arrange a light source at the focal position. (Japanese Patent Laid-Open No. 2009-199927).

The inventor of the second invention of the specification has sought to obtain an edge light type surface illumination device that achieves both suppression of hot spots and local dimming. However, if the technique described in Japanese Patent Laid-Open No. 2001-210122 described above is used to perform local dimming, the method is a method of dividing the light guide plate, and there is a concern about an increase in assembly man-hours and a decrease in strength. In addition, dark lines are generated in the divided portions. On the other hand, the technique described in Japanese Patent Application Laid-Open No. 2009-199927 provides an optical structure for condensing light on the incident surface portion, and what is an optical structure for diffusing light provided on the incident surface side to suppress hot spots. It is difficult to combine.
Therefore, the inventor of the specification 2nd invention provides a substantially parallel groove structure extending in the normal direction of the light incident surface on the light exit surface in order to perform local dimming, and on the light incident surface in order to eliminate hot spots. A light guide plate having a groove shape extending in the direction of the facing surface from the light exit surface was produced. However, a light guide plate having a diffusion structure on the light incident surface and a groove structure on the light output surface that is substantially parallel to the normal direction of the light incident surface contributes to the reduction of hot spots. The inventors of the second invention of the specification have found that a so-called bright line is generated in which a relatively high portion extends linearly (see FIG. G18).
The second invention of the specification has been made in view of the above points, and a light guide plate capable of local dimming with less luminance unevenness such as hot spots and bright lines in the vicinity of the light incident surface on the light exit surface, and the light guide plate. It is an object of the present invention to provide a surface light source device having an optical plate, a display device having the surface light source device, and a television receiver having the display device.

  As a result of intensive studies on the light guide plate, the inventors of the second invention of the specification can eliminate the above-described hot spots and bright lines by providing a light diffusion portion having controlled light diffusion characteristics on the light incident surface. The inventors have found that a uniform luminance distribution can be obtained over the entire light emitting surface, and have completed the second invention of the specification.

That is, the second invention of the specification is as follows.
[1]
At least one light incident surface for receiving light from the light source;
A first surface that is substantially orthogonal to the light incident surface and emits light incident from the light incident surface;
A light guide plate having a second surface substantially orthogonal to the light incident surface and facing the first surface,
The first surface and / or the second surface has a groove structure substantially parallel to the normal direction of the light incident surface,
The entire light incident surface has anisotropic light diffusion characteristics in which the diffusion angle of incident light from the normal direction in the longitudinal direction of the incident surface is greater than the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface. And
The light emission pattern curve of the entire light incident surface with the horizontal axis representing the emission angle of the light emitted from the normal direction of the light incident surface in the longitudinal direction of the light incident surface and the vertical axis representing the intensity appears in the light emission pattern curve. When compared with a normal distribution curve passing through a total of three points: one peak point where the intensity of the emitted light is the peak intensity and two intermediate points where the intensity of the emitted light is half of the peak intensity, the following conditions 1. And / or condition 2. A light guide plate that meets the requirements.
Condition 1. The range of the emission angle where the intensity of the emitted light is 3/4 or more of the peak intensity is narrower than the normal distribution curve.
Condition 2. The range of the emission angle where the intensity of the emitted light is 1/10 or more of the peak intensity is wider than the normal distribution curve.
[2]
The light guide plate according to [1], wherein a diffusion angle of light incident on the light incident surface from the normal direction in the longitudinal direction of the light incident surface is greater than 0 ° and less than 40 °.
[3]
The light guide plate according to [1] or [2], wherein a diffusion angle of light incident on the light incident surface from the normal direction in the longitudinal direction of the light incident surface is greater than 0 ° and not greater than 30 °.
[4]
The light incident surface is divided into two or more partial regions having different light diffusion characteristics;
The two or more types of partial regions are
A first partial region having an anisotropic light diffusion characteristic in which the diffusion angle of the incident light from the normal direction in the longitudinal direction of the incident surface is greater than the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface;
Anisotropy of incident light from the normal direction in the longitudinal direction of the incident surface is smaller than that of the first partial region and larger than the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface The second partial region having the above light diffusion characteristics and / or the diffusion angle of the incident light from the normal direction in the longitudinal direction of the incident surface and the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface are approximately A third partial region having equal isotropic light diffusion properties;
The light guide plate according to any one of the preceding items [1] to [3].
[5]
The light guide plate according to [4], wherein a ratio of at least one of the first to third partial regions per 20 square millimeters of the light incident surface is substantially constant in the surface.
[6]
[4] or [5] ].
[7]
The first to third partial regions are each divided into a plurality of small regions, and the area of at least one small region of the first to third partial regions is 0.2 to 4 square millimeters [4] ] To [6] The light guide plate according to any one of items.
[8]
Any one of [4] to [7] above, wherein the first partial region includes a plurality of concave portions or convex portions having an anisotropic shape in which an opening or a bottom surface is long in a direction substantially perpendicular to a light incident surface longitudinal direction. The light guide plate according to claim 1.
[9]
The light guide plate according to [8] above, wherein at least one of the pitch, depth, and height of the plurality of concave portions or convex portions is irregularly different.
[10]
The light guide plate according to [8] or [9], wherein an angle formed between a major axis direction of the plurality of concave portions or convex portions and a direction perpendicular to the longitudinal direction of the light incident surface is 10 ° or less.
[11]
The light guide plate according to any one of [8] to [10], wherein an average pitch of the plurality of concave portions or convex portions is 50 μm or less.
[12]
The light guide plate according to any one of [8] to [11], wherein an average depth or height of the plurality of concave portions or convex portions is 1 to 50 μm.
[13]
The light guide plate according to any one of [8] to [12], wherein the plurality of concave portions or convex portions are formed by speckle pattern exposure.
[14]
The light guide plate according to any one of [4] to [13], wherein a diffusion angle of light incident on the first partial region from the normal direction in the longitudinal direction of the light incident surface is 5 ° or more and less than 40 °. .
[15]
The light guide plate according to any one of [4] to [14] above, wherein a diffusion angle of light incident on the first partial region from the normal direction in the longitudinal direction of the light incident surface is not less than 0 ° and not more than 30 °. .
[16]
In the distribution with respect to the emission angle of the incident light intensity in the longitudinal direction of the incident surface and the direction perpendicular to the longitudinal direction of the incident surface of the light incident on the first partial region from the normal direction, the emission angle is 0 °. The light guide plate according to any one of [4] to [15] above, wherein the transmitted light intensity is 90% or more of the peak intensity.
[17]
The preceding items [4] to [16], wherein a diffusion angle of light incident on the second partial region or the third partial region from the normal direction in the longitudinal direction of the light incident surface is not less than 0 ° and less than 20 °. The light guide plate according to any one of the above.
[18]
In the distribution with respect to the emission angle of the incident light intensity in the longitudinal direction of the light incident surface of the light incident from the normal direction to the second partial region or the third partial region and the direction perpendicular to the longitudinal direction. The light guide plate according to any one of [4] to [17], wherein the emitted light intensity at an angle = 0 ° is 90% or more of the peak intensity.
[19]
An adhesive layer in which at least a part of the region having an anisotropic light diffusion characteristic existing on the light incident surface is laminated on the light incident surface, and an anisotropic light diffusion layer laminated on the adhesive layer are provided. The light guide plate according to any one of [1] to [18] above.
[20]
The light guide plate according to [19], wherein the adhesive layer is made of a material having a storage elastic modulus G ′ at 100 ° C. of 40,000 to 180,000 Pa.
[21]
The light guide plate according to any one of [1] to [20], wherein the groove structure has a lenticular lens shape.
[22]
The light guide plate according to any one of [1] to [20], wherein the groove structure includes a plurality of random grooves.
[23]
The light guide plate according to [22], wherein an average pitch of the plurality of random grooves is 30 μm or less.
[24]
The light guide plate according to [22] or [23] above, wherein an average depth of the plurality of random grooves is 1 to 50 μm.
[25]
The light guide plate according to any one of [1] to [24], wherein the groove structure is formed from a position 1 to 50 mm inside from the light incident surface side end of the first surface and / or the second surface.
[26]
The light guide plate according to any one of [1] to [25] above,
A plurality of point light sources arranged in the vicinity of the at least one light incident surface of the light guide plate;
A surface light source device.
[27]
A display panel having a display area for displaying light by adjusting light transmission;
The surface light source device according to the preceding item [26] disposed on the back surface of the display panel;
A display device.
[28]
The display device according to [27], wherein the display panel is a liquid crystal display panel.
[29]
The display device according to [27] or [28],
A tuner for receiving broadcast video signals;
A television receiver.

  When a light source comprising a plurality of point light sources is used by the light guide plate of the second invention, a surface light source device capable of local dimming with less luminance unevenness including hot spots and bright lines near the light incident surface on the light exit surface A display device including the surface light source device and a television receiver including the display device can be provided.

An embodiment of the light guide plate of the specification second invention will be specifically described below.
The light guide plate 2 according to the second invention has at least one light incident surface G22 that receives light from a light source, a first surface G21 that emits light incident from the light incident surface, and a first surface that faces the first surface. A groove structure having two surfaces, the first surface and the second surface being substantially orthogonal to the light incident surface, and the first surface and / or the second surface being substantially parallel to the normal direction of the light incident surface (See FIG. G2).

The light incident surface as a whole has a diffusion angle of outgoing light in the light incident surface longitudinal direction G24 (hereinafter also referred to as “first direction”) of incident light from the normal direction thereof. It is larger than the diffusion angle in the direction G25 perpendicular to the longitudinal direction (hereinafter also referred to as “second direction”).
Here, the longitudinal direction of the light incident surface refers to the direction of the long side of the circumscribed rectangle that minimizes the area circumscribed by the light incident surface.
In the light guide plate of the second invention of the specification, as shown in FIG. G1, the horizontal axis represents the emission angle of the incident light from the normal direction of the light incident surface in the first direction, and the vertical axis represents the intensity. The light emission pattern curve of the entire light incident surface has a total of three points: one peak point where the intensity of the emitted light is the peak intensity and two intermediate points where the intensity of the emitted light is half the peak intensity. When compared with the normal distribution curve that passes, at least one of the following two conditions is satisfied.
Condition 1. 1. Conditions where the range of the emission angle where the intensity of the emitted light is 3/4 or more of the peak intensity is narrower than the normal distribution curve The range of the emission angle where the intensity of the emitted light is 1/10 or more of the peak intensity is wider than the normal distribution curve There is no limitation on the difference in the range of the emission angle, but the range of the emission angle where the intensity of the emitted light is 3/4 or more of the peak intensity Is preferably 3% or more narrower (smaller) than that of the normal distribution curve.
In addition, the range of the emission angle that is 1/10 or more of the peak intensity is preferably 5% or more (large), more preferably 10% or more, relative to that of the normal distribution curve.

The light emission pattern curve of the entire light incident surface is, for example, transmitted light of light incident on the surface from the normal direction of the light incident surface using a variable angle color difference meter such as GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. It can be obtained by measuring the angular distribution in the first direction of intensity (distribution of the intensity of transmitted light with respect to the emission angle). In addition, the laser diameter of the light source of the incident laser beam used in that case shall be 3 mm.
Here, when the light incident surface is divided into a plurality of partial regions having different light diffusivities as will be described later, the average value of the light emission pattern curve measured for 10 or more arbitrary points (output for each emission angle). The distribution of the average value of the incident light intensity) is defined as the light emission pattern curve of the entire light incident surface.

The diffusion angle in the first direction and the second direction of the entire light incident surface is not limited, but is preferably in the following range. Here, the “diffusion angle” refers to an angle (FWHM: Full Width Half Maximum) that is twice the angle of the emitted light (the angle at which it attenuates to half the peak intensity (half-value angle)) (see FIG. G1).
The diffusion angle in the first direction and the second direction is appropriately determined according to the arrangement of the point light sources used in combination when the light guide plate is used in the surface light source device and the type of other optical elements such as the diffusion sheet and the reflection sheet. In general, the diffusion angle in the first direction is preferably greater than 0 ° and less than 40 °, more preferably 5 ° or more and less than 25 °. Further, the diffusion angle in the second direction is preferably smaller than the diffusion angle in the first direction and more than 0 ° and less than 30 °, more preferably less than 15 °, and still more preferably 10 °. Is less than.

In addition, the diffusion angle of the entire light incident surface is, for example, Photo Inc. Using a variable angle color difference meter such as Photon manufactured by Nippon Steel and GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. described above, the angular distribution of the output light intensity of the light incident on the light incident surface from the normal direction of the light incident surface (output It can be determined by measuring the distribution of the intensity of the incident light with respect to the emission angle.
Here, when the light incident surface is divided into a plurality of partial regions having different light diffusivities as will be described later, the average value of the angular distributions of the emitted light intensity measured at 10 or more arbitrary points (each outgoing light The distribution of the average value of the outgoing light intensity with respect to the angle) is defined as the angular distribution of the outgoing light intensity over the entire light incident surface.

The light emission pattern curve as described above is obtained by, for example, dividing the light incident surface into two or more types of partial regions having different light diffusion characteristics, and at least one type of partial region (first partial region) is determined by the method. This can be realized by configuring the diffusion angle of the outgoing light in the first direction of the incident light from the linear direction to have anisotropic light diffusion characteristics larger than the diffusion angle in the second direction.
At this time, for example, as shown in FIG. G5, the light incident surface is divided into two or more types of partial regions having different light diffusion characteristics, and at least one type of partial region is divided into a plurality of small regions. It can be preferably used.

  The two or more types of partial regions are at least a first portion having anisotropic light diffusion characteristics in which the diffusion angle in the first direction of incident light from the normal direction is larger than the diffusion angle in the second direction. And a second partial region having an anisotropic light diffusion characteristic in which the diffusion angle in the first direction of incident light from the normal direction is greater than the diffusion angle in the second direction, the first direction The diffusion angle of the incident light from the normal direction to the second partial region smaller than that of the first partial region and / or the diffusion angle in the second direction is substantially the same. And a third partial region having equal isotropic light diffusion characteristics.

  In addition, each light emission pattern curve of each of the first to third partial regions is the same as the condition 1. Alternatively, the condition 2. Is not necessarily satisfied, and may be represented by a normal distribution curve.

  In order to more effectively prevent luminance unevenness, it is preferable that the two or more types of partial regions are present in an appropriate ratio in the light incident surface.

Although there is no specific limitation on the ratio of the area occupied by each partial region in the light incident surface, at least one of the first to third partial regions is divided into a plurality of small regions, and the small regions are incident on the light incident surface. The ratio of the area per 20 square millimeters is preferably 10 to 80%, and the ratio of at least one of the first to third partial areas per 20 square millimeters of the incident surface is substantially constant throughout the surface. It is preferable.
Here, “substantially constant” means that when the proportion of the at least one partial region per 20 square millimeters is measured at any 10 or more locations on the light incident surface, the variance of the proportion is 10% of the average value. It means the following.

  Further, each of the first to third partial regions is divided into a plurality of small regions, and an area of at least one of the first to third partial regions is 0.2 to 4 square millimeters. Is preferred. By setting the area of the small area of each partial area sufficiently small, when using the light guide plate of the second invention of the specification as a surface light source device, the accuracy of alignment of the light source and the light guide plate is strict. No need to ask.

  There is no limitation on the arrangement of the first partial region, the second partial region, and / or the third partial region on the light incident surface. For example, the respective partial regions may be regularly arranged (FIG. G5 (a) to (e)) or may be randomly arranged (FIG. G5 (f)). Each partial region may be arranged so as to cross the light incident surface in the second direction (FIGS. G5 (a) and (b)), or arranged in an island shape without crossing (FIG. G5 (c) ) To (f)). Furthermore, it may be divided into three or more types of partial regions (FIG. G5 (e)).

There is no limitation on the diffusion angle of light incident on each partial region from the normal direction, but it is preferable to be in the following range.
The diffusion angle in the first direction of the first partial region is preferably 5 ° or more and less than 40 °, more preferably 5 ° or more and less than 20 °. The diffusion angle in the second direction is preferably smaller than the diffusion angle in the first direction and greater than 0 ° and less than 40 °, more preferably less than 15 °.

  The diffusion angle in the first direction of the second partial region is smaller than that of the first partial region, and is preferably 0 ° or more and less than 20 °, more preferably less than 10 °. The diffusion angle in the second direction is smaller than the diffusion angle in the first direction of the second partial region, and is preferably 0 ° or more and less than 20 °, more preferably less than 10 °.

  The third partial region has substantially the same diffusion angle in the first direction and the second direction, and is preferably 0 ° or more and less than 20 °, more preferably less than 10 °. Here, “substantially equal” means that the ratio of both is in the range of 0.9 or more and less than 1.1. The diffusion angle in the first and / or second direction of the third partial region may be 0 °.

  In addition, the diffusion angle of each partial region is, for example, Photo Inc. Using a variable angle color difference meter such as Photon manufactured by Nippon Steel and GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. described above, the angular distribution of the outgoing light intensity of the light incident on each partial region from the normal direction of the light incident surface (output It can be determined by measuring the distribution of the intensity of the incident light with respect to the emission angle.

Also, if the size of each partial area is smaller than the laser diameter of the laser light source used for measurement, the diffusion angle of each partial area can be expressed when the angular distribution of the emitted light intensity of each partial area can be expressed as a normal distribution. Is obtained by approximating the angular distribution of transmitted light intensity of light incident on a surface where a plurality of partial areas intersect with each other as an addition of the angular distribution (normal distribution) of outgoing light intensity of each partial area. Is possible (FIG. G10). The normal distribution curve is a curve represented by the following equation, where C is a constant and σ is a standard deviation.

By changing C and σ of each of the two normal distribution curves and determining each value so that the difference between the approximate value obtained by adding the intensities at each angle and the actual measurement value becomes small, the output of each partial region is obtained. An approximate normal distribution of the angular distribution of the incident light intensity is determined. For accurate approximation, the sum of the absolute values of the difference between the approximate value obtained for a total of 171 points and the actual measurement value at every emission angle from −85 ° to 85 ° is less than 150. It is preferable to obtain C and σ. When calculating approximate values, use the Microsoft MICROSOFT EXCEL (registered trademark) solver tool to calculate the C and σ of each of the two normal distribution curves so that the sum of the differences between the approximate values and the measured values is minimized. Changing is useful because C and σ of each normal distribution curve can be obtained in a short time. Further, the same function can be executed by various programming languages, but the method of obtaining the approximate value in the second invention of the specification is not limited to these. The FWHM of the two normal distributions obtained by the above method is defined as the diffusion angle of the first partial region and the second partial region or the third partial region.

In each of the first to third partial regions, the transmitted light intensity of the light at the emission angle = 0 ° is the peak intensity in the angular distribution of the emitted light intensity in the first and second directions of the light rays incident from the normal direction. It is preferable that it becomes 90% or more.
A specific example is shown in FIG. FIG. G16 is an angular distribution of the emitted light intensity in the first direction of the first partial region alone measured using a GC5000L manufactured by Nippon Denshoku Industries Co., Ltd.
In the figure, the intensity of the emitted light at the ◇ (outlined) portion is 90% or more of the peak intensity. In either angular distribution, the outgoing light intensity is 90% or more of the peak intensity at the outgoing angle = 0 °.
As described above, the light diffusion characteristics of the first to third partial regions have a plurality of angular distributions of the emitted light intensity of the emitted light in the first and second directions when a light ray is incident from the normal direction. It is preferable that it does not have a peak and changes gently.

  In the light guide plate according to the second aspect of the specification, it is sufficient that there is at least one light incident surface, and there may be two or more. When two light incident surfaces are provided, the shape of the light guide plate is preferably a flat rectangular parallelepiped having the first surface and the second surface as main surfaces, and the two light incident surfaces are opposed to each other. preferable. In this case, since two opposing light incident surfaces have the same length, there is a merit that the number and type of point light sources can be made the same and parts can be shared.

There is no limitation on the method of imparting anisotropic light diffusion characteristics to the light incident surface (partial region thereof) of the light guide plate of the second specification.
For example, a method of mixing an anisotropic diffusing agent or the like in a translucent film or pressure-sensitive adhesive so that the direction of the major axis is oriented in a specific direction and bonding them to the corresponding region of the light incident surface can be mentioned. It is done. Specifically, an acicular filler having a major axis of 10 to 300 μm and a minor axis of 0.3 to 5 μm, which is added with an acicular filler having a refractive index different from that of the adhesive, is applied while applying a shearing force. By processing, the direction of the major axis can be aligned along the coating direction, and anisotropic light diffusion characteristics can be imparted to the coated region (see JP 2008-34234 A).

In addition, it is also preferable to provide a plurality of concave portions or convex portions having an anisotropic shape in which the opening portion or the bottom surface is long in a specific direction in the region where the light incident surface has anisotropic light diffusion characteristics. The one specific direction is preferably a direction parallel to the second direction.
In addition, when the angle formed by the major axis of the opening (bottom) of the recess (projection) with a specific direction is 40 degrees or less (not 0 degree), the opening of the recess (projection) (Bottom) shall be “having a long anisotropic shape in one specific direction”, but the angle between the major axis of the opening (bottom) of the recess (convex) and the specific one direction is 10 degrees. Preferably, it is 8 degrees or less, more preferably 6 degrees or less, more preferably 4 degrees or less, and most preferably 0 degrees. Here, the major axis of the opening (bottom surface) refers to the long side of the circumscribed rectangle that minimizes the area circumscribing the opening (bottom surface).

  Other than the anisotropic shape where the shape of the opening (bottom surface) is mixed with the concave portion (convex portion) which is the shape of the anisotropic shape long in one specific direction, and the shape of the opening (bottom surface) is long in one specific direction Concave part (convex part) having a shape of (for example, the opening part (bottom surface) is an isotropic shape such as a circle, or the opening part (bottom surface) is an anisotropic shape, but the major axis has a specific direction. May not exist in parallel). However, in the region where the opening (bottom) of the recess (projection) having an anisotropic shape having an opening (bottom surface) long in a specific direction is provided, the recess (projection) having an anisotropic shape. It is preferable that the sum of the areas of the openings (bottom surface) exceeds the sum of the areas of the openings (bottom surface) of the other recesses (projections).

  The ratio of the major axis to the minor axis (major axis / minor axis) of the anisotropic shape is not limited, but is preferably 2 or more, more preferably 10 or more. Here, the minor axis and the major axis refer to the short side and the long side of the circumscribed rectangle having the smallest circumscribed area, respectively.

The anisotropic shape is not limited, and specific examples thereof include a straight line (groove) as shown in FIG. G2 and a substantially elliptical shape as shown in FIG.
The shape of the opening (bottom surface) of the concave portion (convex portion) can be determined by observing an arbitrary portion of the light incident surface with a microscope (such as a scanning electron microscope or a laser confocal microscope).

  The pitch in the first direction of the recesses (projections) is not limited, but the average pitch is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The average pitch is preferably 580 nm (the central wavelength of visible light) or more, and more preferably 780 nm (the entire visible light region) or more.

  When the average pitch is set to such a value, a claw or the like is hardly caught on the concave portion or the convex portion at the time of handling, and handling properties are improved. Furthermore, since the light diffused by the light guide plate included in the surface light source device of the specification second invention is visible light (electromagnetic wave of 380 nm to 780 nm), it is average to sufficiently exhibit the diffusion effect by the concave portion or the convex portion. The pitch is preferably a value as described above.

Here, the pitch in the first direction of the concave portions (convex portions) is between adjacent valley bottoms (in the case of concave portions) or peaks (in the case of convex portions) in an arbitrary cross section parallel to the first direction of the light incident surface. This refers to the horizontal distance (the distance in the direction parallel to the light incident surface) (see FIG. 13). If the valley bottom (mountain peak) is flat, the pitch is determined with the center as the valley bottom (peak peak).
Further, the average pitch in the first direction of the concave portions or convex portions is a concave portion present in 100 μm arbitrarily extracted from an arbitrary vertical cross section parallel to the light exit surface of the region where the concave portion (convex portion) of the light incident surface is formed. It is set as the average value of the pitch of (convex part).
The (average) pitch in the first direction of the concave portion (convex portion) is determined by using an arbitrary cross section parallel to the first direction of the region where the concave portion (convex portion) of the light incident surface is formed. It can be determined by observing and measuring with a focusing microscope or the like.

There is no limitation on the size (depth / height) of each recess (projection).
For example, the minor axis of the opening (bottom surface) may be 580 nm to 50 μm, 780 nm to 20 μm, or 1 to 10 μm. Further, the major axis of the opening (bottom surface) may be, for example, 5 μm or more and 2 cm or less.
The depth (height) may be, for example, 500 nm to 50 μm, 700 nm to 30 μm, or 5 to 10 μm. The average depth (height) of the concave portion or convex portion is also preferably 500 nm to 50 μm, more preferably 700 nm to 30 μm, and further preferably 5 to 10 μm.

  Here, the depth (height) of the concave portion (convex portion) is the higher peak among the peaks on both sides constituting each concave portion in an arbitrary cross section of the region where the concave portion (convex portion) of the light incident surface is formed. Vertical distance (between the bottom of the lower valley and the top of the convex part of the valleys on both sides constituting each convex part) (the distance in the direction perpendicular to the light incident surface) ( This refers to the difference in elevation between the top of the mountain and the bottom of the valley (see FIG. 13). Moreover, the average depth (height) of the concave portion or the convex portion is that of the concave portion (convex portion) existing at 100 μm arbitrarily extracted from an arbitrary vertical cross section of the region where the concave portion (convex portion) of the light incident surface is formed. The average value of depth (height). The size of the concave portion (convex portion) can be determined by observing and measuring an arbitrary portion of the light incident surface with a microscope (such as a scanning electron microscope or a laser confocal microscope).

  However, when the shape of the concave portion (convex portion) is a groove (ridge) parallel to the second direction, the length is preferably larger than the length of the light emitting surface of the point light source in the second direction. That is, the length of the groove (畝) is preferably equal to or larger than the size of the light emitting surface of the point light source. In FIG. G2, the groove 23 has a length that crosses the light incident surface 22 in the second direction 25, but the length of the groove (溝) does not necessarily cross the light guide plate. Good.

It is preferable that at least one of the shape, size (depth, height) and pitch in the first direction of the plurality of concave portions (convex portions) is randomly (irregularly) different because the luminance unevenness reducing effect is improved. .
Here, the difference in size and pitch means that the value obtained by multiplying the standard deviation by 3 (3 sigma) exceeds 10% of the average value.

  There is no limitation on the method of forming a plurality of recesses or projections having an anisotropic shape having an opening or a bottom that is long in a specific direction on the light incident surface of the light guide plate of the second invention of the specification. The above-described methods ((1) to (3)) can be employed. Moreover, the same thing as what was mentioned above can be used also about the adhesive layer used in that case, and the resin layer which has a some recessed part or convex part on the surface.

[Light diffusion layer]
Next, the light diffusion layer will be described. The light diffusing layer is a layer that can be used to give anisotropic or isotropic light diffusing characteristics to the first to third partial regions of the light incident surface. A film having a concavo-convex structure in a method of forming a plurality of concave portions or convex portions on a light incident surface by laminating a film having a light guide plate using a translucent adhesive or the like, an anisotropic shape in the film This corresponds to a translucent film mixed with an anisotropic diffusing agent when a translucent film mixed with a diffusing agent is bonded to a light guide plate using an adhesive or the like.
The light diffusion layer may be a layer having a function of diffusing incident light anisotropically or isotropically, and a conventionally known layer can be used, and the material, shape, and the like are not limited.
The thickness of the light diffusion layer is not limited, but is preferably about 25 to 500 μm from the viewpoint of adhesiveness with the adhesive layer. If it is too thin, the stiffness will be insufficient, and the workability at the time of pasting on the substrate will be reduced. On the other hand, if it is too thick, the stiffness will be too strong and the workability of pasting will be reduced. It is more preferable that

The light diffusing layer may be a layer having a concavo-convex structure on its surface, like the film having a concavo-convex structure in the method (3) described above, and further, on the surface laminated on the transparent base film layer. You may have a multilayer structure containing the transparent resin layer which has an uneven structure.
In this case, the material of the light diffusion layer or the transparent resin layer having a concavo-convex structure on the surface is not limited, and examples thereof include a cured product of a photopolymerizable resin composition.
The material and thickness of the transparent base film layer are not limited, and examples of the material include highly transparent materials such as polyethylene terephthalate, polycarbonate, and polystyrene (for example, the total light transmittance is 90% or more, and the haze is 1). 0.0 or less), and the thickness can be, for example, 20 to 250 μm, more preferably 50 to 125 μm.

  As the photopolymerizable resin composition, the same photopolymerizable resin composition as that described above for the present invention and the first invention of the specification can be used.

[Light scattering processing of facing surface]
In the second surface of the light guide plate of the specification second invention, in order to make the light distribution on the first surface uniform, a light scattering process having a gradation that becomes dense toward the direction away from the light incident surface is formed. Can do. In the case of a surface light source device for a display device, it is preferable that a uniform mountain-shaped light emission distribution with the highest luminance at the center of the screen is easy to visually recognize while improving the uniformity of the light emission distribution. The density of the light scattering process at the central portion of the second surface may be increased.

  Examples of light scattering processing having gradation that becomes denser in the direction away from the light incident surface include, for example, a layered (printed) part of reflective or diffusive material or a part formed with uneven shapes (hereinafter collectively referred to as “dots”). ))) With a gradation pattern that gradually increases in area as it moves away from the incident surface (in the case of printing, it may be a gradation pattern that gradually becomes darker) The gradation pattern provided so that a pitch may become narrow as it leaves | separates from a surface is mentioned. Examples of the shape of the dots in this case include a circle and a quadrangle, and the size can be, for example, about 0.1 to 2.0 mm.

  In the case where the light scattering process as described above is provided on the second surface of the light guide plate of the specification second invention, in order to further reduce the luminance unevenness, as shown in FIG. It is preferable not to form dots at the facing positions, or to reduce the dot density or to make each dot small (thin). By doing so, luminance unevenness can be further reduced, so that P / G described later can be further increased.

[Groove structure of first surface and / or second surface]
The light guide plate of the second invention of the specification has a groove structure substantially parallel to the normal direction of the light incident surface on the first surface and / or the second surface. The groove structure is preferably a lenticular lens shape or a plurality of random grooves. Whether the groove structure is provided on the first surface or the second surface may be appropriately determined in consideration of ease of manufacturing, ease of handling, and the like. Although it may be provided on both the first surface and the second surface, for example, when the light scattering process as described above is provided on the second surface, it is preferably provided only on the first surface.
Furthermore, from the viewpoint that the hot spots near the light incident part can be reduced, the groove structure starts from a position 1 to 50 mm inside from the light incident surface side end of the first surface and / or the second surface. It is preferable to provide it so that it may extend in the opposite direction.

  The lenticular lens shape preferably extends in a direction substantially parallel to the normal direction of the light incident surface and is provided in parallel. The pitch of the lenticular lens shape is preferably 20 to 500 μm, and the depth is preferably 20 to 500 μm (see FIG. G19). If the pitch is too small, accurate processing of the lenticular lens is difficult, and if the pitch is too large, moire between the pixels of the liquid crystal panel is likely to occur. If the depth is too shallow, the straightness of light decreases, and if the depth is too deep, accurate machining becomes difficult or easily damaged.

Next, a plurality of random grooves will be described.
That the plurality of grooves are random means that at least one of the cross-sectional shape, pitch, and depth of the plurality of grooves is randomly (irregularly) different.
FIG. G19 shows an example in which a plurality of random grooves substantially parallel to the normal direction of the light incident surface are provided on the first surface.

There is no limitation in the cross-sectional shape of each groove | channel, For example, it can be set as V shape or U shape.
The pitch of the grooves refers to a horizontal distance between the valley bottoms of adjacent grooves (a horizontal distance in a direction parallel to a surface having a plurality of random grooves). When the valley bottom is flat, the pitch is determined with the center as the valley bottom. The cross-sectional shape and width of the groove may change along the extending direction of the groove. The depth of the groove is the vertical distance between the peak of the higher peak of the peaks on both sides of each groove and the valley bottom of the groove (distance in the direction perpendicular to the surface having a plurality of random grooves). (Elevation difference between mountain top and valley bottom).
The depth of the groove may change gently or steeply along the extending direction, and as a result, there may be a portion where the groove is interrupted, but it is preferable that it does not change if possible.
Specific examples of a plurality of random grooves that can be preferably used in the second invention of the specification are shown in FIGS. G21A and G21B. FIG. G21A shows a specific example of a plurality of random grooves having anisotropic light diffusion characteristics in which the diffusion angle in the direction perpendicular to the groove (described later) is 30 degrees and the diffusion angle in the direction horizontal to the groove is 1 degree. FIG. G21B is a surface showing a specific example of a plurality of random grooves having anisotropic light diffusion characteristics in which the diffusion angle in the direction perpendicular to the grooves is 60 degrees and the diffusion angle in the direction horizontal to the grooves is 1 degree. It is a profile figure.

The average pitch of a plurality of random grooves is not limited, but is preferably 30 μm or less, more preferably 20 μm or less, still more preferably 15 μm or less, and particularly preferably 10 μm or less. The average pitch of the plurality of random grooves is preferably 580 nm (the central wavelength of visible light) or more, more preferably 780 nm (the entire visible light region) or more.
Since the pixel pitch of the display panel used in combination with the light guide plate and the structure pitch of the optical sheet are approximately 100 to 600 μm and 50 to 150 μm, respectively, the average pitch of a plurality of random grooves is set to such a value. If set, generation of moire due to spatial interference with a display panel or an optical sheet used in combination with the light guide plate can be prevented. Furthermore, if the average pitch is set to such a value, the claw and the like are not easily caught in the groove during handling, and handling is improved. Furthermore, since the light guided by the light guide plate of the specification second invention is visible light (electromagnetic wave of 380 nm to 780 nm), in order to sufficiently exhibit the effect of direct evolution of light by a plurality of random grooves. The lower limit value of the average pitch is preferably a value as described above.
The average depth of the plurality of random grooves is not limited, but is preferably 1 to 50 μm, more preferably 5 to 10 μm.

The slope angle of the groove has a great influence on the straightness of light. That is, when a groove structure is provided on the first surface or the second surface, light that spreads outside is reflected by the slope of the groove in the light guide plate and returned to the light guide plate to improve the straightness of the light. it is conceivable that. Therefore, the slope angle of each groove is preferably 40 to 60 degrees. Therefore, it is preferable that the plurality of random grooves provided on the first surface or the second surface account for 5% or more of the groove angle within the range of 40 degrees to 60 degrees. More preferably, it is 10% or more. Of these, the greater the proportion occupied by 45 ± 5 degrees contributes to the improvement in straightness.
Here, the “slope angle” is a general term for an angle formed by a surface tangent to each groove and a surface having a groove structure in a cross section perpendicular to the groove of a surface having a plurality of random grooves.
And about the ratio which a slope angle has in the range of 40 degree-60 degree | times, the arbitrary perpendicular | vertical of the surface which has a random several groove | channel by microscope observation (a scanning electron microscope, a laser confocal microscope, etc.) A range with a distance of 300 μm is extracted arbitrarily from the cross section (cross section perpendicular to the groove structure), and tangents with points at 0.5 μm points from the end of the range are extracted. It is determined by measuring an angle (acute angle) formed by the surface having the groove.

The light guide plate of the second invention of the specification can be incorporated into a surface light source device and used for various display devices such as a notebook PC, a portable information terminal, a desktop PC monitor, a digital camera, and a television receiver.
In particular, the surface light source device incorporating the light guide plate of the second invention of the specification uses a plurality of point light sources as the light source, and has less luminance unevenness (hot spots / bright lines) in the vicinity of the light incident surface and is uniform over the entire light exit surface. Therefore, it is suitable for use in a liquid crystal display device because a large and thin liquid crystal display device can be provided at low cost and / or in a narrow frame.
The specific modes of the surface light source device, the display device, and the television receiver incorporating the light guide plate of the second invention of the specification may be the same as those of the surface light source device, the display device, and the television receiver of the present invention. it can.

  Next, in the present invention, also as a light guide plate (or a layer having a plurality of concave portions or convex portions having an anisotropic shape whose opening or bottom surface is long in one direction, which is bonded to the light incident surface of the light guide plate). The third invention of the present specification relating to a suitably usable diffusion sheet will be described.

  The third invention of the specification relates to a sheet that diffuses light from a light source, and more particularly to a diffusion sheet that diffuses only in one direction and hardly diffuses in a direction orthogonal to a certain direction.

  Currently, various lighting fixtures using light emitting diodes (LEDs) have been developed and sold. However, since the LED is a point light source with strong directivity, there is a drawback that a large number of LEDs are required to irradiate a wide area. Then, the technique regarding the diffusion plate and diffusion sheet for installing between a light source and irradiation object is examined.

  For example, Japanese Patent No. 3413519 discloses a light homogenizing device that forms a fine engraving surface texture on a photosensitive medium by exposing the photosensitive medium with irregular non-planar speckles.

  In Japanese Patent Publication No. 2004-508585, a desired speckle pattern is realized by appropriately selecting various lens combinations, aperture dimensions, and distances of respective members used for exposure, and exposure is performed on a photosensitive medium. Thus, a method for producing a master for an anisotropic diffuser is disclosed. Also, final masters having output angles of 100 ° x90 °, 60 ° x40 °, 50 ° x10 °, 20 ° x1 °, 6 ° x0.3 °, 60 ° x0.5 °, 130 ° x70 ° are produced. An embodiment to that effect has been disclosed. The notation “A ° × B °” means that the diffusion angle in the direction in which the diffusion angle is maximum is A ° and the diffusion angle in the direction in which the diffusion angle is minimum in the diffuser manufactured using the master. It means that the value is B °.

  Japanese Patent Laid-Open No. 2005-24886 discloses that only light incident from a specific direction is scattered, light incident from a direction other than the specific direction is transmitted, and scattered light intensity of light incident from the specific direction is transmitted. A projection-type image display device is disclosed in which anisotropic scattering films having different half-value widths on two scattering surfaces are arranged on the front surface as a screen. A holographic method has been disclosed as a method for producing such a film. The screen has a vertical diffusion angle of 32 °, a horizontal diffusion angle of 75 °, and a vertical diffusion angle of the screen of 42 °. An embodiment with a directional diffusion angle of 103 ° is disclosed.

  Japanese Patent Application Laid-Open No. 2006-337906 discloses a light diffusion film having an anisotropic diffusion angle. As a method for producing such a light diffusing film, a method of sandblasting in a state where a blast gun is laid on a mold base material is disclosed. Further, a mold having an average unevenness interval of 0.13 mm in the X-axis direction and 0.07 mm in the Y-axis direction is produced, a light diffusion film is produced using the mold, and a vertical direction is produced using the light diffusion film. An example in which an anisotropic screen having a diffusion angle of 32 ° and a horizontal diffusion angle of 51 ° is produced is disclosed.

  In order to realize a line illumination system such as a line illumination for inspection in a factory by using a plurality of point light sources such as LEDs, the point light sources are arranged in a line and light is arranged in a line by the diffusion sheet. (Hereinafter referred to as “horizontal direction”).

  In the diffusion sheet, the low horizontal diffusibility corresponds to a portion corresponding to a vertical foot from the point light source and a vertical foot from an intermediate point between the adjacent point light sources on the irradiated surface. This is not preferable because unevenness in brightness and darkness is generated between the portion and the portion to be performed. Although it is conceivable to reduce the unevenness of light and darkness by increasing the number of point light sources and reducing the intervals, there is a tendency to increase power consumption and manufacturing cost.

  Further, the diffusion sheet has a high diffusivity in a direction orthogonal to the direction in which the point light sources are arranged (hereinafter referred to as “vertical direction”). Since the intensity of the light applied to the portion corresponding to the perpendicular foot from the point light source is lowered, it is not preferable as a line illumination system.

  In addition, when the line of the said linear illumination system is short, you may diffuse the light to a specific direction with the said diffusion sheet by using the said point light source as one. Also in this case, it is preferable that the light diffusibility is high in the specific direction and the light diffusivity in the direction orthogonal to the specific direction is low, as in the case where there are a plurality of point light sources.

  Therefore, a diffusion sheet that diffuses light from a point light source in the horizontal direction and does not diffuse in the vertical direction is preferable. As a means for expanding the light from the point light source only in one direction as described above, a regular surface structure such as a lens array is known. However, when a regular surface structure is used, for example, the irradiated light is changed. Moire interference fringes may occur when taking an image. For this reason, the image quality may be impaired, which is not preferable.

  Therefore, the third invention of the specification is that in a line illumination system using a point light source, even when the number of point light sources is reduced and the interval is widened, the uniformity of light on the irradiated surface is high and the light on the irradiated surface is It is an object of the present invention to provide a diffusion sheet that can suppress a decrease in the intensity of light and does not generate moire interference fringes, and a lighting device having the diffusion sheet.

  The inventors of the third invention of the specification have made extensive studies in order to achieve the above object, and as a result, the interference light diffused through the holographic diffuser having a minimum value of the diffusion angle of the emitted light of 0.1 degrees or less. A diffusion sheet produced by transferring from a sub-master mold obtained by exposing and developing a photosensitive medium with a speckle pattern obtained by diffusing light in only one direction and orthogonal to a certain direction The inventors have found that almost no diffusion occurs in the direction, and have completed the third invention of the specification.

That is, the third invention of the specification is as follows.
[1]
There is a non-periodic surface uneven structure on at least one surface, and there are a direction in which the diffusion angle of outgoing light of the light incident on the surface uneven structure from the normal direction has a maximum value and a direction in which the minimum value is present. A diffusion sheet wherein the ratio of the maximum value to the minimum value is 200 or more, the maximum value is 40 degrees or more and less than 100 degrees, and the minimum value is less than 0.5 degrees.

[2]
The diffusion sheet according to [1], wherein a ratio of the maximum value of the diffusion angle to the minimum value of the diffusion angle is 400 or more.
[3]
The diffusion sheet according to [1] or [2], wherein a streak pattern is provided in an oblique direction with respect to a direction in which the diffusion angle of the emitted light has a minimum value.
[4]
The diffusion sheet according to [3], wherein an angle formed between the streak pattern and a direction in which a diffusion angle of emitted light has a minimum value is 5 degrees or more.
[5]
The diffusion sheet according to [3] or [4], wherein the streak pattern is aperiodic.
[6]
The diffusion sheet according to any one of [3] to [5], wherein the streak pattern is discontinuous.
[7]
The diffusion sheet according to any one of [1] to [6], wherein the minimum value of the diffusion angle of the emitted light is 0.2 degrees or less.
[8]
The diffusion sheet according to any one of [1] to [7], wherein a minimum average pitch of the surface uneven structure is 20 μm or less.
[9]
The diffusion sheet according to any one of [1] to [8], wherein a maximum average pitch of the surface uneven structure is 5 mm or more.
[10]
The diffusion sheet according to [1] to [9], wherein the ratio of the maximum average pitch of the surface uneven structure to the minimum average pitch of the surface uneven structure is 200 or more.
[11]
The diffusion sheet according to [10], wherein the ratio of the maximum average pitch of the surface uneven structure to the minimum average pitch of the surface uneven structure is 400 or more.
[12]
The diffusion sheet according to any one of [1] to [11], wherein the maximum average aspect ratio of the surface uneven structure is 0.5 or more.
[13]
The diffusion sheet according to any one of [1] to [12], wherein the surface uneven structure is formed using a speckle pattern by interference exposure.
[14]
The diffusion sheet according to [13], wherein the speckle pattern is obtained by interference light diffused through a holographic diffuser having a minimum value of a diffusion angle of outgoing light of 0.1 degrees or less.
[15]
The diffusion sheet according to any one of [3] to [6], wherein the streak pattern is formed by sandblasting.
[16]
The diffusion sheet according to any one of [3] to [6], wherein the streak pattern is formed by a density distribution of the surface uneven structure.
[17]
A line illumination system comprising at least one point light source and the diffusion sheet according to any one of [1] to [16].
[18]
The line illumination system according to any one of [3] to [6], wherein the point light source is a light emitting diode (LED).
[19]

  By exposing and developing the photosensitive medium with the speckle pattern obtained by the interference light diffused through the holographic diffuser having a minimum value of the diffusion angle of the emitted light of 0.1 degrees or less, the non-difference derived from the speckle pattern is obtained. The method for producing a diffusion sheet according to any one of [1] to [16], wherein a submaster mold having a periodic surface irregularity structure is produced and transferred from the submaster mold at least once.

  According to the diffusion sheet of the third specification of the present invention, even when the interval is widened by reducing the number of point light sources in a line illumination system using point light sources, the uniformity of light on the irradiated surface is high, and the irradiated surface It is possible to suppress a decrease in the intensity of light at, and no moiré fringes are generated.

  Next, an embodiment (hereinafter referred to as “embodiment”) of the third invention of the specification will be described in detail with reference to the drawings. However, the third invention of the specification is not limited to the following description, and various modifications can be made within the scope of the gist thereof. In addition, the dimension ratio of drawing is not limited to the ratio of illustration.

  FIG. H1 is a schematic diagram illustrating the configuration of the line illumination system according to the first embodiment as viewed obliquely from above. As shown in FIG. H1, the light from the plurality of point light sources H1 arranged in the horizontal direction has a non-periodic surface uneven structure on at least one surface according to the first embodiment, and is in the normal direction. A direction in which the diffusion angle of the outgoing light of the light incident on the surface concavo-convex structure has a maximum value and a direction in which the minimum value is present, and the ratio of the maximum value of the diffusion angle to the minimum value of the diffusion angle is 200 or more The irradiation surface H3 is irradiated through the diffusion sheet H2 having the maximum value of 40 degrees or more and less than 100 degrees and the minimum value of less than 0.5 degrees.

  The point light source H1 has a function of emitting light, and its display form, dimensions, and light distribution range are not limited. Although it is preferable to use a self-light-emitting light source as the point light source H1, the method is not limited, and examples thereof include an LED, an incandescent lamp, a halogen lamp, a mercury lamp, a xenon lamp, a sodium lamp, and a visible light laser. Among them, the LED is preferable because it has a low divergence of emitted light, so that it is easy to obtain a line-shaped illumination system that maintains high brightness even on the irradiation surface, high luminous efficiency, and miniaturization of the light source. Alternatively, the light source may be a single light source such as a COB type (Chip On Board type) LED or a plurality of light sources having a configuration in which a plurality of LED chips are mounted.

  Further, instead of the point light source, a linear light source such as a hot cathode tube or a cold cathode tube may be used.

  The diffusion sheet H2 includes a base material layer made of a light-transmitting and flat base material, and has a surface uneven structure on at least one surface of the base material layer. When using as a line-shaped illumination system, it is preferable to install the point light source H1 on the surface side having the surface uneven structure with respect to the diffusion sheet H2.

  As the base material layer, a light-transmitting sheet, film, film, plate, or the like can be used. As a material of the base material layer, an organic material, an inorganic material, or a composite material composed of an organic material and an inorganic material can be used. Here, an organic material such as an organic polymer material is a preferable material because it is excellent in workability such as cutting. Examples of the organic polymer include polycarbonate, polyurethane, polyacrylonitrile, polyvinyl alcohol, polyvinyl acetal, polyester, polyamide, polystyrene, polysulfone, cellulose, triacetyl cellulose, cellulose acetate, polyethylene, polypropylene, polyvinyl fluoride, polyvinylidene fluoride, Polytrifluorochlorovinyl, vinylidene fluoride-tetrafluoroethylene copolymer, polyethersulfone, poly (meth) acrylate, butadiene-acrylonitrile copolymer, polyether-polyamide block copolymer, ethylene-vinyl alcohol copolymer, cycloolefin polymer, etc. However, it is not limited to these. The thickness of the base material layer is preferably 40 μm or more. Moreover, it is preferable that the light transmittance of a base material layer is 85% or more.

  The concavo-convex structure on the surface of the diffusion sheet H2 is a structure composed of a large number of fine protrusions, and the protrusions are any of a substantially conical shape, a substantially spherical shape, a substantially ellipsoidal shape, a substantially lenticular lens shape, and a substantially parabolic shape. Alternatively, the protrusions may be connected by a continuous curved surface. It is preferable that at least one of the height and pitch of the protrusions is aperiodic. “Aperiodic” as used herein means that at least one of the height and pitch of several adjacent protrusions is random.

  Specifically, the uneven surface structure of the diffusion sheet H2 can be formed as follows. First, a submaster mold in which a speckle pattern is formed in advance by interference exposure is manufactured, and a master mold is manufactured by applying a metal to the submaster mold by a method such as electroforming to transfer the speckle pattern to the metal. . Furthermore, a speckle pattern is transferred to the surface of the light-transmitting substrate by shaping the light-transmitting substrate with an ultraviolet curable resin using a master mold (speckle pattern made of a cured ultraviolet curable resin) Form the layer on the surface of the substrate.). This speckle pattern corresponds to the surface uneven structure of the diffusion sheet H2.

  The speckle pattern is a light distribution pattern having random intensity generated by interference in the space after coherent light passes through the diffusion plate. A substrate having a photosensitive resin layer is installed in the space. By being exposed and developed, the surface is converted into a random surface uneven structure, and a submaster mold having the structure can be manufactured. In the present specification, this random surface uneven structure is also referred to as a speckle pattern.

  As for the detailed manufacturing method of the above-mentioned submaster type, a submaster having a non-periodic surface uneven structure derived from a speckle pattern by exposing and developing a photosensitive medium with interference light diffused through a holographic diffuser. A sheet having a concavo-convex structure can be obtained by producing a mold and transferring the surface structure from the sub-master mold to the sheet. By adjusting the size, shape, and direction of the speckle pattern, the surface uneven structure of the diffusion sheet H2 is adjusted, and the average pitch of the uneven structure can be controlled. As a method for adjusting the size / shape and direction of the speckle pattern, for example, a known method disclosed in Japanese Patent No. 3390954 can be used.

  Further, the uneven surface structure of the diffusion sheet H2 characterized by the speckle pattern may be provided only on one side of the diffusion sheet H2, or may be provided on both sides.

  In the case of the line illumination system according to the first embodiment, the diffusion sheet H2 is light-transmitting in order to irradiate light from the point light source onto the irradiation surface H3, and corresponds to the minimum value of the diffusion angle of the emitted light. The ratio of the maximum value of the diffusion angle of the emitted light is 200 or more, more preferably 400 or more. By using such a diffusion sheet H2, for example, in a line illumination system using a point light source, even when the number of point light sources is reduced and the interval is widened, the uniformity of light on the irradiated surface is increased. Is possible. Such a diffusion sheet H2 can be obtained by using a holographic diffuser having a speckle pattern with high anisotropy as a holographic diffuser used in the exposure for producing the above-mentioned sub-master type. The anisotropy in the holographic diffuser is given by the ratio of the maximum value of the diffusion angle to the minimum value of the diffusion angle of the holographic diffuser when the light transmitted through the holographic diffuser exhibits a different diffusion angle depending on the direction. It is done. The holographic diffuser having a highly anisotropic speckle pattern used to increase the ratio of the maximum value of the diffusion angle to the minimum value of the diffusion angle of the diffusion sheet H2 is specifically the minimum of the diffusion angle. The value is preferably 0.1 degrees or less, more preferably 0.05 degrees or less, and still more preferably 0.03 degrees or less. Further, the maximum diffusion angle is preferably 5 degrees or more, more preferably 10 degrees or more, and still more preferably 20 degrees or more.

  In the above-described method for producing a diffusion sheet by interference exposure, conventionally, a diffusion sheet has been produced using other diffusers such as a holographic diffuser filed glass having a certain level of diffusibility. However, by using a holographic diffuser having a diffusibility of a certain level or more, it is possible to manufacture the diffusion sheet H2 in which the ratio of the maximum value of the diffusion angle of the emitted light to the minimum value of the diffusion angle of the emitted light is 200 or more. Impossible. On the other hand, by using the holographic diffuser having the minimum value of the diffusion angle described above, the diffusion sheet H2 in which the ratio of the maximum value of the diffusion angle of the outgoing light to the minimum value of the diffusion angle of the outgoing light is 200 or more Can be manufactured.

  The minimum value (perpendicular direction) of the diffusion angle of the emitted light from the diffusion sheet H2 is preferably less than 0.5 degrees, more preferably less than 0.5 degrees in order to efficiently irradiate the irradiation surface H3 with light from the point light source. It is 2 degrees or less, more preferably 0.1 degrees or less.

  The maximum value (horizontal direction) of the diffusion angle of the emitted light from the diffusion sheet H2 is preferably 40 degrees or more, and more preferably 60 degrees or more in order to suppress unevenness of light between point light sources. The maximum value of the diffusion angle is preferably less than 100 degrees.

The diffusion angle of the emitted light is, for example, a variable angle photometer (GC-5000L) manufactured by Nippon Denshoku Industries Co., Ltd. or a beam profiler (NanoS) manufactured by Photon Inc.
The distribution of transmitted light intensity with respect to the emission angle of the light incident on the surface layer having the concavo-convex structure of the diffusion sheet H2 from the normal direction to the diffusion sheet H2 is measured using Can be obtained by obtaining a range (half-value width) of the diffusion angle that is a value of more than half of the above. The normal direction with respect to the diffusion sheet H2 is a direction perpendicular to the surface of the diffusion sheet H2.

  As a specific size of the surface uneven structure, the maximum ratio of the maximum value of the diffusion angle of the outgoing light to the minimum value of the diffusion angle of the outgoing light is set to 200 or more, particularly from the viewpoint of increasing the maximum diffusion angle. The average aspect ratio is preferably 0.5-3. The aspect ratio is defined by the ratio (height / width) of the height of the convex portion to the width of the convex portion at a position that is 1/2 the height of the convex portion. The maximum average aspect ratio is given by the maximum value of the average aspect ratio in each direction obtained by scanning the surface of the diffusion sheet in various directions.

  The minimum value of the average pitch of the surface concavo-convex structure of the diffusion sheet H2 is that the ratio of the maximum value of the diffusion angle of the outgoing light to the minimum value of the diffusion angle of the outgoing light is increased to 200 or more, in particular, the maximum diffusion angle is increased. From a viewpoint, it is preferable that it is 100 micrometers or less, More preferably, it is 20 micrometers or less, More preferably, it is 10 micrometers or less, More preferably, it is 5 micrometers or less. Here, by setting the thickness to 20 μm or less, it is possible to further suppress a rough feeling on the appearance of the diffusion sheet H2. Further, the minimum value of the average pitch is preferably 580 nm (the central wavelength of visible light) or more, and more preferably 780 nm (the upper limit wavelength of visible light) or more. The average pitch is the average of the pitches between the peaks or the bottoms of the surface uneven structure of the diffusion sheet H2, and is observed using an optical microscope, a scanning electron microscope, a laser microscope, and a surface shape measuring instrument. Can be measured. The minimum value of the average pitch is given by the minimum value of the average pitch in each direction obtained by scanning the surface of the diffusion sheet in various directions.

  The maximum value of the average pitch of the surface concavo-convex structure of the diffusion sheet H2 is that the ratio of the maximum value of the diffusion angle of the outgoing light to the minimum value of the diffusion angle of the outgoing light is 200 or more. From the viewpoint, it is preferably 1 mm or more, more preferably 5 mm or more, and further preferably 10 mm or more. The maximum value of the average pitch is given by the maximum value of the average pitch in each direction obtained by scanning the surface of the diffusion sheet in various directions.

  Further, the diffusion sheet H2 has a ratio of the maximum average pitch to the minimum average pitch of the surface uneven structure from the viewpoint that the ratio of the maximum value of the diffusion angle of the output light to the minimum value of the diffusion angle of the output light is 200 or more. However, it is preferable that it is 200 or more, More preferably, it is 400 or more, More preferably, it is 600 or more.

  The diffusion sheet H2 may be composed of two or more layers. For example, a surface layer having a surface concavo-convex structure may be formed on a smooth substrate layer with an ultraviolet curable resin.

  FIG. H2 is a schematic diagram showing the diffusion sheet H2 according to the second embodiment as viewed from above. The diffusion sheet H2 has a non-periodic anisotropic surface uneven structure on at least one surface, and as shown in FIG. H2, streaks obliquely with respect to the direction H6 in which the diffusion angle of the emitted light shows the minimum value. A pattern H5 is formed in the same plane. The streak pattern H5 includes, for example, a plurality of grooves or protrusions (ridges) provided substantially parallel to the diffusion sheet H2. Alternatively, the streak pattern H5 is formed by changing the density distribution of the surface uneven structure into a streak. By forming the streak pattern H5, when the surface having the concavo-convex structure is rubbed and scratched, the effect that the scratch is lost in the streak pattern H5 is less visible. In addition, since the streak pattern H5 is formed, when the uneven surface is stressed, an effect of preventing the occurrence of scratches by rubbing along the streak pattern H5 is also exhibited.

  The average pitch of the streak pattern H5 is preferably 2 mm or less, more preferably 1 mm or less, and still more preferably 0.5 mm or less for improving the scratch resistance.

  Here, the average pitch of the streak pattern H5 is the average of the pitch of the streak pattern that can be visually confirmed, and can be measured by observing using an optical microscope, a loupe, or the like. As will be described later, in the case of the streak pattern H5 formed by sandblasting or the like, the interval between the irregularities of the streak pattern H5 can be measured as a pitch. Further, when the streak pattern H5 is formed by the density distribution of the surface uneven structure, the density density interval can be measured as the pitch.

  The angle H7 of the streak pattern H5 with respect to the direction H6 that gives the minimum value of the diffusion angle of the emitted light is preferably 5 degrees or more, more preferably 10 degrees or more for sufficient scratch resistance.

  In order not to inhibit the diffusibility of the diffusion sheet H2, the angle H7 is preferably less than 30 degrees, more preferably less than 20 degrees.

  The non-periodic streak pattern H5 means that moire interference fringes occur when the diffusion sheet H2 is used between a light source and a display device composed of regularly arranged pixels such as a liquid crystal panel. It is preferable because it is difficult to do.

  For sufficient abrasion resistance, the streak pattern H5 is preferably discontinuous.

  The streak pattern H5 can be formed by subjecting the sub-master type or diffusion sheet H2 having a surface uneven structure to sand blasting obliquely in the direction H6 that gives the minimum value of the diffusion angle of the emitted light, for example. it can.

  For example, rubbing with a roll or a wire having a sandpaper or a concavo-convex surface obliquely against the submaster type or diffusion sheet H2 having a surface concavo-convex structure, for example, in a direction H6 giving the minimum value of the diffusion angle of the emitted light It can be used as a method for forming the streak pattern H5.

  When the streak pattern H5 is formed by sandblasting, sandpaper, roll, wire, or the like, the average aspect ratio of the streak pattern H5 is 0.2 or less in order to avoid adverse effects on the diffusibility of the diffusion sheet H2. Is preferable, more preferably 0.1 or less, and still more preferably 0.05 or less.

  Another method for forming the streaky pattern H5 is to adjust the exposure intensity and the pitch of the speckle pattern when producing a sub-master type by interference exposure, thereby distributing the density of the sub-master type surface uneven structure. You can also have it. By providing the density of the surface uneven structure, the streak pattern H5 can be visually recognized in an oblique direction with respect to the direction H6 that gives the minimum value of the diffusion angle of the emitted light.

  The third invention of the specification can be suitably used in the field of an illuminating device having a line light source system and an inspection device.

Next, a description will be given of a fourth invention of the present specification relating to a bonding method and a bonding jig that can be suitably used for manufacturing a light guide plate used in the present invention.
Specification 4th invention relates to a pasting method and a pasting jig, especially relates to a pasting method and a pasting jig suitable for pasting an optical film on one end face of a plate-like member.

  The main surface of a film-like member having two substantially parallel principal surfaces, or the principal surface of a plate-like member having a substantially parallel two principal surfaces and a narrow end face located between the edges of the two principal surfaces, are optical. Products and methods of pasting films and protective films are well known. On the other hand, the product which bonded the optical film to the end surface of a plate-shaped member, and the method to bond were few and were not common. One reason for this is that the end face rarely had a positive function in the use of the plate-like member.

  However, in recent years, a plate-like member whose end face has a positive function has been proposed. As an example, a light guide plate used as a component of an edge light type surface light source device in a liquid crystal display device can be given. In the edge light type surface light source device, a light guide plate is disposed on the back surface of the liquid crystal display panel, and a light source is disposed on one end surface (side surface) of the light guide plate. With this structure, it is possible to reduce the thickness as compared with a direct surface light source device in which a light source is directly disposed on the back surface of a liquid crystal display panel. A normal light guide plate is a rectangular transparent resin plate having a thickness of about 0.5 to 10 mm and slightly larger than the liquid crystal display panel. One end surface (side surface) is a light incident surface, and the main surface on the liquid crystal display panel side is Used as a light exit surface. Such a light guide plate is used in lighting applications including indoor lighting and automobile lighting in addition to liquid crystal display devices.

  Some light guide plates described above have a tape-like optical sheet bonded to one end surface for the purpose of improving optical characteristics. Specifically, a light guide plate in which a reflective sheet is bonded to an end surface other than the light incident surface for the purpose of reducing light leakage from the end surface, or anisotropic light on the light incident surface (end surface) for the purpose of reducing luminance unevenness. A light guide plate on which a diffuser sheet is bonded has been proposed (see, for example, JP-A-2011-3532).

  However, in JP 2011-3532 A, there is a description that the anisotropic light diffuser sheet is bonded to the light guide plate with a highly transparent double-sided adhesive tape. There is no description.

  In addition, when an optical film is bonded to one end surface of a plate-like member having two substantially parallel principal surfaces and one or more end surfaces, it may be necessary to bond so that air bubbles do not enter the interface. . For example, in the example of the light guide plate described above, when a reflection sheet is bonded to the end face, even if bubbles enter the interface, the same effect can be obtained, so that there is no major problem if it does not peel off. However, in the case where the above-mentioned anisotropic light diffuser sheet is bonded to the light incident surface, the presence of bubbles adversely affects the optical characteristics and a desired light diffusion effect cannot be obtained. Furthermore, the presence of bubbles often becomes a problem in appearance.

  Therefore, if air bubbles enter the interface where the optical film is bonded, the optical film may be peeled off and reattached, or the air bubble may be pushed out by hand to allow air inside the air bubbles to escape from the interface. Although considered, these methods are not productive. In particular, when an optical film is bonded to a plurality of stacked light guide plates, for example, several tens of centimeters with respect to the side end surfaces of the light guide plates that are recessed due to unevenness of the end surfaces of the light guide plates. It is difficult to paste a strip-shaped optical film without deviating over the above length, and it is also difficult to eliminate bubbles by the above method. Moreover, even if it is one plate-shaped member, when one end surface is rough, similarly, it is difficult to eliminate air bubbles in the recessed portion.

  The fourth invention of the specification has been made in view of the above points, and an object thereof is to provide a method for efficiently bonding an optical film to one end face of a plate-like member without bubbles.

  The inventors of the specification 4th invention, as a result of earnest study, a bonding jig provided with a member having shape followability, and a bonding method using the bonding jig solved the above-mentioned problems. As a result, the fourth invention of the specification was completed.

That is, the specification 4th invention is as follows.
[1]
A tape-like member in which an adhesive material layer and an optical film layer are laminated on one end face of a plate-like member having two substantially parallel principal surfaces and one or more end faces, and the one end face of the plate-like member A method of laminating a tape-shaped member having a width substantially equal to or narrower than the thickness,
A laminating step in which the adhesive layer of the tape-shaped member is opposed to the one end surface, and the tape-shaped member is laminated on the one end surface;
A sticking jig comprising a member having shape followability, and an adhesion step of tracing the optical film layer one or more times while applying pressure in the longitudinal direction of the one end face;
A laminating method.
[2]
The laminating method according to [1], wherein the laminating step includes a step of pressing a plurality of locations on the optical film layer laminated on the one end surface to the one end surface.
[3]
The laminating method according to the preceding item [1] or [2], wherein the laminating step and the adhesion step are performed in a state where a plurality of the plate-like members having the same shape are stacked in a multistage manner.
[4]
The bonding method according to [3], wherein the adhesion step includes a step of simultaneously tracing one end surface of the plurality of plate-like members in the longitudinal direction with a member having the shape following property.
[5]
In the above item [3] or [4], the laminating step and the adhesion step are steps performed in a state where a plurality of plate-like members are stacked in a multi-step manner with a step between adjacent plate-like members being 500 micrometers or more. The bonding method described.
[6]
The preceding item is a step that is performed in a state where the plurality of plate-like members having the same shape are stacked in a multi-stage, and the adhesion step is a step that is performed in a state where the plate-like members are made one by one The pasting method according to [1] or [2].
[7]
The bonding method according to any one of [1] to [6], wherein a surface roughness of one end surface of the plate-shaped member is 500 micrometers or more.
[8]
The bonding method according to any one of [1] to [7], wherein the thickness of the plate member is in a range of 0.5 to 10 millimeters.
[9]
The bonding method according to any one of [1] to [8], wherein the surface of the optical film layer has an uneven structure having light diffusibility.
[10]
The bonding method according to any one of [1] to [9], wherein the optical film layer has a pencil hardness of 5H or less.
[11]
The lamination step and the adhesion step are such that the length of the tape-like member is longer than the length of one end surface of the plate-like member, and at least one end of the tape-like member protrudes in the longitudinal direction from the one end surface. The bonding method according to any one of [1] to [10], wherein the bonding step includes a cutting step of cutting a portion of the tape-shaped member protruding from one end surface of the plate-shaped member. [12]
The bonding method according to any one of [1] to [11], wherein the tape-shaped member has both ends, and has a marking in the vicinity of at least one end.
[13]
The bonding method according to any one of [1] to [12], wherein the tape-shaped member is supplied from a reel onto one end surface of the plate-shaped member in the stacking step.
[14]
A laminating jig for tracing an optical film laminated on an end face of a plate-like member via an adhesive material layer, comprising a member having shape followability.
[15]
Located on the surface of the bonding jig, a slipperiness-imparting layer made of a slipperiness-providing material,
A shape following layer made of a material having a shape following property located inside the slipperiness-imparting layer;
A bonding jig according to the preceding item [14].
[16]
The bonding jig according to [14] or [15] above, wherein the material having the shape following property is a material having a rubber hardness of 10 to 70.
[17]
[16] The bonding jig according to [14] or [15] above, wherein the material having the shape following property is an elastic body.
[18]
The bonding jig according to [17], wherein the elastic body is made of rubber or sponge.
[19]
The bonding jig according to [17], wherein the elastic body is a sponge having a sponge hardness of 5 to 50. [20]
The bonding jig according to [14] or [15], wherein the material having the shape following property is a plastic deformable body.
[21]
A bonding jig for tracing the optical film laminated on the end face of the plate-like member via an adhesive material layer, the bonding jig comprising a member having shape following property;
A reel for holding the tape-shaped member wound in order to supply a tape-shaped member including the laminated adhesive material layer and the optical film on one end surface of the plate-shaped member;
And a pinch roller for moving along the one end face with the two main surfaces of the plate-like member sandwiched therebetween.

  According to the bonding method and the bonding jig according to the fourth specification of the present invention, it becomes possible to efficiently bond the optical film to the one end surface of the plate-shaped member without bubbles.

  Hereinafter, modes for carrying out the specification fourth invention (hereinafter abbreviated as “embodiments”) will be described in detail with reference to the drawings as appropriate. The fourth specification invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the invention.

  In the bonding method according to the embodiment, an adhesive material layer and an optical film layer are laminated on one end surface of a plate-like member I1 having two substantially parallel main surfaces and one or more end surfaces as shown in FIG. This is a method of laminating a tape-like member I2 having a width substantially equal to or narrower than the thickness of one end surface of the plate-like member I1. The laminating step according to the embodiment includes a laminating step in which the adhesive material layer of the tape-like member I2 is opposed to one end face of the plate-like member I1, and the tape-like member I2 is laminated on one end face of the plate-like member I1. A bonding jig provided with a member having shape followability, and an adhesion step of tracing the optical film layer one or more times while applying pressure in the longitudinal direction of one end surface of the plate-like member I1.

  The plate-like member I1 used in the bonding method according to the embodiment is a member having two substantially parallel main surfaces and one or more end surfaces, and is made of, for example, transparent resin or glass, and the main surface is rectangular. A plate-shaped member, more specifically, a light guide plate. The thickness of the plate-like member I1 to which the bonding method according to the embodiment can be preferably applied is 0.5 mm to 10 mm, more preferably 1 mm to 5 mm, and most preferably 1.5 mm to 4 mm.

  The tape-like member I2 used in the bonding method according to the embodiment refers to a tape-like member in which an adhesive material layer and an optical film are laminated, for example. Such a tape-like member I2 is a known laminate in which a pressure-sensitive adhesive dissolved in a solvent is applied to one of the main surfaces of the optical film and dried, or a double-sided pressure-sensitive adhesive sheet is stacked on one of the main surfaces of the optical film. The laminated body produced without bubbles can be produced by a method of cutting into a tape shape.

  In the following, the bonding method according to the embodiment is a light diffusion film (optical) in which the plate-like member I1 is a light guide plate, one end face is a light incident surface of the light guide plate, and the tape-like member I2 is laminated with an adhesive layer. An example of a kind of film will be described.

  In the case of a light guide plate for a television, the size of the main surface of the light guide plate is determined by the size of the television screen. For example, the length of the long side is about 70 cm in the case of a 32-inch television, but reaches 133 cm in the case of a 60-inch television. For example, when the light guide plate has a thickness of 3 mm and is bonded over the long side of the light guide plate for a 32-inch television, the size of the light diffusion film to be bonded is, for example, a width of 2.8 mm and a length of 70 cm. Become.

  The width of the light diffusing film is set between 110% and 20% with respect to the thickness of the light guide plate, depending on the optical performance required, preferably 100% to 40%, more preferably 99% to 50%, Most preferably, it is 95% to 80%. If the width of the light diffusing film is 110% or less with respect to the thickness of the light guide plate, there is little possibility of partial peeling due to being caught by interference with other members. If the width is 20% or more, desired optical characteristics such as light diffusibility can be obtained.

  The lower limit of the length of the light diffusion film is a length that can secure an area in which light sources (LED chips) are arranged, and the upper limit can be several cm longer than the length of one end face of the light guide plate to be bonded.

  As shown in FIG. 12, in the state where a plurality of light guide plates 1 are stacked in the main surface direction, when the light diffusion film 2 is bonded to one end surface of each light guide plate, each end surface is adjacent to each light guide plate. There is a difference in level, and there are things that are deep and those that have popped out. At this time, if the light diffusion film is pasted by hand on one end surface of the recessed light guide plate, and the light guide plate is thin, for example, 3 mm, and the hand does not enter the recessed portion, the light diffusion film If one end of the light guide plate protrudes in the longitudinal direction of the one end face of the light guide plate, it is preferable because the position is adjusted so that it does not deviate from the width of the one end face of the light guide plate over the length of the film. Moreover, you may perform a close_contact | adherence process in the state which made the plate-shaped member one sheet at a time.

  It is more preferable that the end portion on the bonding end side protrudes in the longitudinal direction so that it can be securely gripped, and it is also possible to suitably adopt a state where both end portions of the light diffusion film protrude from one side surface of the light guide plate. By making the light diffusing film protrude from one end face of the light guide plate, the visibility is improved, and when sticking one by one to the stacked plate-like members, it is possible to prevent forgetting to stick. This has the advantage that it can be easily inspected. In addition, there is an advantage that it is easy to peel off when re-bonding is necessary, for example, when the film has deviated from the width of one end face of the light guide plate.

  The protruding length is an amount sufficient for gripping, and is preferably 5 mm to 30 mm. If it is less than 5 mm, it is difficult to grip, and if it is 30 mm or more, the light diffusion film tends to be wasted. It is preferable to remove the protruding portion by using a cutter at least in the stage before the product is finished and at least before becoming a product.

  The thickness of the light diffusion film is preferably 30 to 300 μm. If thickness is 30 micrometers or more, it exists in the tendency for it to reduce at the time of bonding. In addition, when the thickness is 300 μm or less, bubbles tend to be easily extracted in the adhesion process. Further, the thickness of the adhesive layer is preferably 10 to 70 μm. If the thickness is 10 μm or more, the adhesive force can be sufficiently secured, and it tends to be possible to suppress natural peeling due to thermal shock or the like. Moreover, if thickness is 70 micrometers or less, it exists in the tendency for it to become easier to extract a bubble by the contact | adherence process.

  In the bonding method according to the embodiment, the optical film layer and one end face of the plate-like member are traced once or more in the longitudinal direction of the one end face while applying pressure on the optical film layer with a member having shape followability. Air bubbles between them can be easily removed. The member having the shape following property will be described later. At this time, in the laminating process before the adhesion process, it is possible to include a temporary fixing process in which a plurality of locations on the optical film layer are pressed against one end surface.

  Moreover, a lamination | stacking process and a contact | adherence process can be performed in the state which piled up the several plate-shaped member which has the same shape. Furthermore, a lamination process can be performed in a state where a plurality of plate-like members having the same shape are stacked in multiple stages, and a contact process can be performed in a state where the plate-like members are made one by one.

  When the optical film layer is transparent, as shown in FIG. I3, a marking I3 can be provided on one or both ends of the tape-like member I2 in order to improve visibility. When one end surface of the plate-like member I1 is longer than about 1 m, it is possible to bond with two optical films. In this case, for example, two markings provided on the tape-like member are attached to the plate-like member. Aligned with both ends of one end surface of the tape, or bonded after aligning the center of the marking, or by bonding two films after aligning the marking with the end surface and the center respectively. It becomes easy to paste in position. Moreover, when bonding one sheet at a time to a multi-layered plate-like member, there is an advantage that it is possible to prevent forgetting to bond and to facilitate inspection.

  In the case where the tape-like member sticks out from the one end surface of the plate-like member in the longitudinal direction, the marking position can be appropriately selected depending on the end of the tape-like member or the end of the plate-like member. As a marking method, there are a method of drawing a line with a marker and a method of pasting a colored tape on a portion to be marked. As the marker, commercially available sign pens, magic inks, pens using thermal fading ink, and the like can be used. Pens using thermal fading ink are marked on the final product because the marking disappears due to frictional heat generated in the process of sliding on the film layer while applying pressure with a shape-following member after pasting the tape-like member It can be preferably used when there is a need not to leave. Various tapes can be used as colored tapes, but if there is a need to leave no marking on the final product, the tape can be peeled off after bonding by marking with a slightly sticky tape. Can be preferably used.

  As shown in FIG. I4, the tape-like member I2 can be supplied to one end surface of the plate-like member I1 by a reel cartridge. The reel cartridge is a tape-like member I2 wound around a reel, and the tape-like member I2 composed of an optical film layer, an adhesive material layer, and a release paper layer is peeled off from the release paper I5 and wound up. The plate-like member I1 is supplied onto one end surface of the plate-like member I1 so that the side faces the one end surface of the plate-like member I1. The guide roller I10 can be provided so as not to deviate from the width of one end surface of the guide. Further, it is preferable to provide a pinch roller I9 that sandwiches the two main surfaces of the plate-like member I1 from both sides. Moreover, a lamination process and an adhesion | attachment process can also be performed simultaneously or continuously by providing the bonding jig I4 which has the shape followability mentioned later in a supply port. In the tape-like member I2, the optical film layer may have a function of a release layer. In this case, the tape-like member I2 may not include the release paper I5.

  A bonding jig I4 according to the embodiment shown in FIG. I5 is a jig suitable for performing the adhesion process in the bonding method according to the embodiment. The bonding jig I4 according to the embodiment includes a contact portion I6 that comes into contact with the surface of the optical film layer, and the contact portion I6 is a member having shape followability, so that one of the plate-like members I1 is applied while applying pressure. By tracing once or more in the longitudinal direction of the end face, the tape-like member I2 can be brought into close contact with the one end face of the plate-like member I1 while eliminating bubbles. Here, “tracing” includes both a case where the bonding jig I4 including a member having a shape following property is slid on the surface of the optical film layer and a case where it is rolled.

  The member having the shape following property of the bonding jig I4 is preferably an elastic body such as rubber or sponge, or a plastic deformation body having the shape following property. Further, the hardness of the material having the shape following property is preferably 10 to 70, more preferably 35 to 65, and most preferably 40 to 60. In addition, when the material which has shape followability cannot measure rubber hardness with sponge etc., sponge hardness can be substituted, and it is preferable that it is 5-50 in that case. By using such a shape-following member, especially when the hardness is 5 or more, the applied stress is efficiently propagated to the stress in the direction perpendicular to the one end surface, effectively eliminating bubbles. However, it tends to be able to be in close contact. At this time, the elastic body can withstand long-term use. If the hardness is 70 or less, the shape followability to the applied stress is excellent, the contact area can be secured above a certain level even if the jig is slightly inclined with respect to the width direction, and the uniformity of the bubble removal in the width direction of one end face is excellent. There is a tendency.

  As shown in FIGS. I5 (b) and I5 (c), the labeling jig 4 according to the embodiment has a surface roughness of one end face of the plate-like member I1 of 500 μm or more, or multistage stacking. Even in the case where the step between adjacent one end faces of the plate-like member I1 is about 500 μm to 5 mm, the shape following property is sufficient, so that it is possible to remove bubbles by tracing a plurality of plate-like members I1 at a time. Furthermore, even if there is a concavo-convex structure having light diffusibility on the surface of the optical film, even if the optical film is a flexible film having a pencil hardness of 5H or less, it is difficult to be scratched. Can be maintained.

  In addition, in the state which applied the pressure in a close_contact | adherence process, the length (contact length) which the bonding jig | tool I4 which concerns on embodiment is contacting with the longitudinal direction of the tape-shaped member I2 is 0.5 mm-15 mm. Preferably, 0.8 mm to 5 mm is more preferable, and 1 mm to 3 mm is most preferable. When the contact length is 0.5 mm or more, bubbles tend to be efficiently eliminated, and when the contact length is 15 mm or less, the applied force tends to be propagated to stress for efficiently eliminating bubbles, The operator is less tired when manually pasting.

Materials of shape-following members are acrylic rubber, nitrile rubber, isoprene rubber, urethane rubber, ethylene propylene rubber, chlorosulfonated polyethylene, epichlorohydrin rubber, chloroprene rubber, silicone rubber, styrene / butadiene rubber, butadiene rubber, fluorine rubber , Polyisobutylene, butyl rubber, nitrile / butadiene rubber, tetrafluoroethylene / propylene rubber, hydrogenated NBR, chlorinated polyethylene, ethylene acrylate rubber, norbornene rubber, fluorosilicone rubber, natural rubber, polyurethane foam, polyethylene foam, EVA It is selected from foam, silicone foam, acrylic foam, polyimide foam, EPDM foam, and the like. Specifically, silicone foam manufactured by Dow Corning Bar Silastic J-RTV and Code Seal <Soft> manufactured by Nippon Valqua Industries, Ltd. can be preferably used.

  Contact part I6 of bonding jig I4 concerning an embodiment may consist only of shape following layer I8 which consists of material of a member which has shape followability, as shown in Drawing I6 (a). Alternatively, as shown in FIGS. I6 (b) and I6 (c), on the outermost surface portion of the contact portion I6 of the bonding jig I4, a slip applying layer 7 made of a slip providing material can be provided smoothly. One end surface can be traced in the longitudinal direction, and workability can be further improved. In particular, when the surface of the optical film layer in contact with the contact portion I6 of the bonding jig is smooth, the effect is remarkable. In this case, the slip-imparting layer 7 may be a laminate with the shape following layer I8 existing on the inner side, or may have an inclined structure. In the case of lamination, the shape following layer I8 may be coated with a slip-providing material, or the slip-providing material may be fixed to the shape following layer I8. The presence of this slip-imparting material gives the effect of extending the life of the internal shape tracking layer I8 and the effect of preventing the scattering of the shape tracking material, and by appropriately replacing only the slip-imparting layer 7, the bonding jig is lengthened. It can also be used.

  As the slipperiness imparting material, polyethylene, polypropylene, vinyl chloride, fluororesin, polyoxymethylene and the like are selected. In the case of a film or tube having heat shrinkability, the shape following layer I8 is coated with a slipperiness-imparting material, and then adhered by heating and shrinking, so that wear of the material due to slippage between the two can be suppressed and bonding treatment can be performed. The tool life can be extended.

  The bonding jig I4 can include a grip portion by a human hand or a robot arm in addition to the contact portion I6. In this case, it is preferable that the contact portion I6 and the grip portion are integrated, and the contact portion I6 is slid in the longitudinal direction of the one end face while applying pressure. In other words, the applied stress can be propagated to the stress for efficiently eliminating the bubbles by controlling and applying the dynamic friction better than the rolling friction. In that case, a rectangular parallelepiped, a square weight, or the like is selected as the shape of the bonding jig I4, and one side or one vertex thereof is set as the contact portion I6, and pressure is applied.

  Moreover, if it adheres one piece at a time, it can also be set as the shape which has the groove | channel which matched the shape of the bonding jig 4 with the thickness of the plate-shaped member I1.

  On the other hand, the shape of the bonding jig is a roll, and both sides of the plate-like member, for example, both end faces are sandwiched and pressed so as not to give a moment with the rolls, and the plate-like member is fed while being rotated and bonded. it can. In this case, since the perpendicular stress is applied to the one end face almost efficiently by pressing with the roll, it is possible to achieve close contact while removing bubbles.

  As one of the methods for producing the light guide plate of the present invention, the method for pasting the pressure-sensitive adhesive sheet (seal) having a concavo-convex structure to the light guide plate substrate has been described above. About this invention specification 5 invention regarding the manufacturing method of the sheet | seat with an adhesive material in which the uneven structure was formed in the surface suitable for using in this method, an opening part or a bottom face which shows a remarkable effect also in a concavo-convex structure is one direction. The following description will be given in the form of an example of a concavo-convex structure (hereinafter referred to as “vertical groove structure”) composed of a plurality of concave portions or convex portions having a long anisotropic shape. However, the fifth invention of the specification is not limited to the illustrated longitudinal groove structure, and can be applied to a sheet with an adhesive (seal) having various uneven structures.

(Vertical groove sheet roll manufacturing method)
First, a sheet in which a resin layer having a longitudinal groove structure (also referred to as a “longitudinal groove layer”) is laminated on a base material is wound around a core tube in a roll shape (hereinafter referred to as “longitudinal groove sheet roll”). .) Will be described.
A base material wound in a roll shape around a core tube is unwound from the core tube (unwinding step), a photopolymerizable resin composition is applied (application step), and a cylindrical shape having a concavo-convex structure on the surface of the cylindrical surface By irradiating with ultraviolet rays while pressing against the mold, a UV curable resin layer obtained by curing the photopolymerizable resin composition is formed on one side of the substrate (curing step), and the substrate and the resin layer are laminated. A method for producing a roll-shaped film having a concavo-convex structure on the surface by winding the resulting sheet in a roll shape around another core tube (winding step) is well known (for example, JP-A-7-32476). reference).
In this method, by using a cylindrical mold having a longitudinal groove structure on the surface of the cylindrical surface, a longitudinal groove sheet roll J1 in which a sheet made of a base material and a longitudinal groove layer is wound in a roll shape can be produced. At this time, in order to prevent the longitudinal groove layer from being damaged, it is preferable to wind up so that the longitudinal groove layer is inside the roll. Preferable examples include a longitudinal groove sheet roll J1 in which the base material is a PET film having a thickness of 125 μm and the longitudinal groove layer is a UV curable resin layer having a thickness of 15 μm.

(Manufacturing method A1: Adhesive vertical groove sheet roll)
Secondly, a sheet in which a heavy release separator, an adhesive layer, a base material, and a longitudinal groove layer are laminated in this order using the longitudinal groove sheet roll wound around a core tube in a roll shape (hereinafter referred to as “adhesive”). A first method for producing a longitudinal groove sheet roll with material ”will be described (FIG. J1).
A material prepared by laminating a pressure-sensitive adhesive film in which a heavy release separator, a pressure-sensitive adhesive layer, and a light release separator are laminated in this order on a core tube (hereinafter referred to as “pressure-sensitive film roll”) is prepared.
While unwinding the sheet 1 which consists of a base material and a longitudinal groove layer from the said longitudinal groove sheet roll J1 (longitudinal groove sheet roll unwinding process), unwinding an adhesive film from the said adhesive film roll (adhesive film roll unwinding process) The light release separator is peeled from the unrolled adhesive film to form a sheet 2 composed of a heavy release separator and an adhesive layer (peeling step), and laminated so that the adhesive layer of the sheet 2 and the base material of the sheet 1 are in contact with each other. Bonding is performed by applying pressure with a sheet roll (bonding step).
By winding the sheet, in which the heavy release separator, the adhesive layer, the base material, and the longitudinal groove layer are laminated, in a roll shape onto another core tube after the pasting (adhesive longitudinal groove sheet roll winding step) The fluted sheet roll J2 with adhesive is manufactured. Also in the longitudinal groove sheet roll J2 with an adhesive, it is preferable to wind up so that the longitudinal groove layer is inside the roll. Preferable examples include PET film having a heavy release separator having a thickness of 75 μm, an adhesive for an optical adhesive having a thickness of 25 μm, a PET film having a thickness of 125 μm, and a UV curing having a vertical groove layer having a thickness of 15 μm. The adhesive grooved fluted sheet roll J2 which is a resin layer is illustrated.

(Manufacturing method A2 of longitudinal groove sheet roll with adhesive material: coating method)
Third, a sheet in which a heavy release separator, an adhesive layer, a base material, and a longitudinal groove layer are laminated in this order using the longitudinal groove sheet roll is wound around a core tube in a roll shape (hereinafter referred to as “adhesive”). A second method for producing a “longitudinal groove sheet roll with a material” will be described (FIG. J2).
A heavy release separator is prepared by winding a core tube in a roll (hereinafter referred to as “heavy release separator roll”).
The sheet 1 composed of a substrate and a longitudinal groove layer is unwound from the longitudinal groove sheet roll J1 (longitudinal groove sheet roll unwinding step), and a coating device (for example, a die coater) is used to apply a solvent Apply the adhesive material dissolved in (application process), volatilize the solvent by heating to form a sheet 2 with an adhesive layer (drying process), and unwind the heavy release separator from the heavy release separator roll (heavy release) Separator roll unwinding step), laminating so that the heavy release separator and the adhesive layer of the sheet 2 are in contact, and applying pressure with a roll (bonding step). By winding the sheet, in which the heavy release separator, the adhesive layer, the base material, and the longitudinal groove layer are laminated, in a roll shape onto another core tube after the pasting (adhesive longitudinal groove sheet roll winding step) The fluted sheet roll J2 with adhesive is manufactured. About the suitable aspect of the longitudinal groove sheet roll J2 with an adhesive material, it is the same as the 1st method mentioned above.
However, since the adhesive material is directly applied in the second production method, it takes time to store the adhesive material before use, called a curing period, in order to stabilize the physical properties of the adhesive material. The curing period is preferably about 2 weeks, although it depends on the adhesive used.

(Half slit sheet manufacturing method)
Fourth, a method for producing a half slit sheet using the longitudinal groove sheet roll with longitudinal groove adhesive will be described.
The sheet wound in a roll shape includes a direction in which the sheet is unwound from the roll and wound (hereinafter referred to as “MD direction”) and a width direction of the roll (hereinafter referred to as “TD direction”).
On the other hand, in the case of a sheet composed of a base material laminated on the light incident surface of the light guide plate used in the present invention via an adhesive layer (adhesive layer) and a resin layer having a longitudinal groove structure, the diffusion angle of the longitudinal groove structure is The low direction (direction parallel to the ridge line of the longitudinal groove) is the thickness direction (short side direction) of the light incident surface, and the direction in which the diffusion angle of the longitudinal groove structure is high (the direction perpendicular to the ridge line of the longitudinal groove) is the incident light. The width direction of the surface (long side direction) is required.
Therefore, in the following, a half slit processing method in the case where the longitudinal groove sheet roll J2 is a highly diffusive sheet in the TD direction will be described with reference to FIG. The half slit processing method in the case of a sheet will be described.

(Manufacturing method B of a half slit sheet in the case of high diffusion in the TD direction)
FIG. J3 shows a processing flow from the upper left to the lower right.
In the case of a sheet roll having a high diffusion in the TD direction, a fluted sheet roll (21 with a high diffusion in the TD direction) J21 is used with a single blade so that the length in the MD direction becomes the sheet width of the final product of the half slit sheet. To cut in the TD direction (step B1). The width at this time is parallel to the direction in which the half slits are inserted in the subsequent process, and is performed to determine how many half slits are to be formed on one sheet.
Next, it cuts in MD direction with a single blade so that the length of a TD direction may become the length of the long side of the sheet | seat bonded to the light-incidence surface of a light-guide plate, and it is set as the longitudinal groove sheet J3 with an adhesive material (process). B2). At this time, one end portion in the TD direction may be cut or both end portions may be cut, but the latter is preferable from the viewpoint of quality uniformity. However, the length of the long side of the sheet to be bonded to the light incident surface of the light guide plate need not be limited to the same length as the long side of the light incident surface of the light guide plate. This includes cases where the length is shorter than the length. This is because a plurality of individual longitudinal groove seals J5 with adhesive material may be bonded in the long side direction, or may be bonded slightly short.
Finally, the flute separator with adhesive material is cut off in the TD direction with a single blade so that the longitudinal groove sheet J3 with adhesive is the length of the short side of the sheet bonded to the light incident surface of the light guide plate. The half slit which cuts to a vertical groove layer, a base material, and an adhesion layer is performed, and it is set as the half slit sheet J4 (process B3). At this time, the direction of inserting the half slit is substantially parallel to the high diffusion direction and is perpendicular to the ridgeline of the longitudinal groove structure.

(Method C of producing a half slit sheet in the case of high diffusion in the MD direction)
FIG. J4 shows a processing flow from the upper left to the lower right.
In the case of sheet rolls with high diffusion in the MD direction, the longitudinal groove sheet roll with adhesive (MD direction high diffusion) J22 is slit into small rolls so that the width in the TD direction is the sheet width of the final product of the half slit sheet. And rewinding (step C1). The width at this time is orthogonal to the direction in which the half slits are inserted in the subsequent process, and is performed in order to determine how many half slits are formed on one sheet. The dimension that restricts the number of strip-like individual adhesive-attached longitudinal groove seals in the case of the half-slit sheet J4 is the TD direction in J22. The roll roll J221 is more versatile as an intermediate stock. Because the light guide plate has many types of light incident surface lengths, the thickness of the individual strips with adhesive material corresponding to the thickness of the light incident surface is limited to some extent, so it corresponds to the light guide plate This is because the length to be determined can be determined in a later step.
Next, the longitudinal groove sheet roll small roll J221 with adhesive is cut in the TD direction with a single blade so that the length in the MD direction is the length of the long side of the sheet to be bonded to the light incident surface of the light guide plate. Thus, a longitudinal groove sheet J3 with an adhesive material is formed (step C2).
Finally, the longitudinally peeled sheet J3 with adhesive is cut off in the MD direction with a single blade so that the length in the TD direction is the length of the short side of the sheet bonded to the light incident surface of the light guide plate. The half slit which cuts to a longitudinal groove layer, a base material, and an adhesion layer is performed, and it is set as the half slit sheet J4 (process C3). At this time, in order to reliably divide the adhesive-attached longitudinal groove seal J5, the cross section as shown in detail in FIG. Don't do this.

(marking)
Since the adhesive-attached fluted seal J5 bonded to the light guide plate is an optical member, the transparency is high, and the light guide plate to which the adhesive-attached fluted seal J5 is bonded is distinguished from the non-bonded light guide plate. It is very difficult. For this reason, it is difficult to inspect the missing product in which the adhesive-attached longitudinal groove seal J5 is not bonded in the light guide plate manufacturing process. In addition, there is no alignment mark at the time of bonding, and some mark is necessary for automation even in manual work. For this reason, it is preferable to make a visible marking on the longitudinal groove seal J5 with adhesive according to the present invention.
As a position for marking, a position where the surface light source device can be easily set as a position that does not affect optically, for example, a position described in a half slit sheet J41 with marking shown in FIG. In addition, as shown in the figure, the half slit sheet J41 with marking is illustrated as being marked at two places on both sides, but if necessary, one marked at one place, Marking may be performed near the center of the half slit sheet J41 with marking.

(Method of marking from the roll at the same time as sheeting)
A marking adding method using the above-described step C2 will be described with reference to FIG.
The pressure-sensitive adhesive-equipped longitudinal groove sheet roll small roll J221 manufactured in step C1 is unwound so that the longitudinal groove layer formed in the inner winding becomes front. Then, using the marking head, one line is drawn in the TD direction, the roll is further fed out, and the second line is drawn (step C2-1). As a result, a line is drawn in the TD direction on both sides of the scheduled cutting position. In Fig. J5, only one head is illustrated, but if two heads are used, it is possible to draw two lines at the same time. For example, it is not necessary to work while successively stopping the feeding of the roll, and the machining speed can be increased. However, if all of them are realized, the apparatus becomes large and expensive. Therefore, it is preferable to design the apparatus according to the production amount.
Next, the marking-equipped longitudinal groove sheet J31 is manufactured by cutting between the two markings in the TD direction with a single blade (step C2-2).
When cutting, make sure to insert a blade between the markings, and to minimize the influence of marking as a surface light source device (optical interference such as blocking or coloring the LED light as a point light source) Therefore, the marking position is preferably 0 mm or more and 20 mm or less, more preferably 0.5 mm or more and 10 mm or less, and most preferably 1 mm or more and 5 mm or less from the end of the longitudinal groove sheet J31 with marking. In this way, it is possible to place a marking on the edge where the LED does not exist when a single longitudinal groove seal J5 with a dressing material is pasted on the light incident surface, and when a plurality of sheets are pasted, the marking position is Optical interference can be suppressed by being between LED and adjacent LED in a surface light source device.

(Marking type)
Further, as a method for preventing the optical interference, the marking color is preferably black or gray. Accordingly, it is possible to prevent the light entering the light guide plate from the LED from being colored. The marking line thickness is preferably 50 μm to 2 mm, more preferably 100 μm to 1 mm, and most preferably 200 μm to 500 μm. By setting the marking line thickness within this range, it has been confirmed that the optical interference can be suppressed to the minimum while the function as a visual mark is sufficiently exhibited. In this case, even if the marking is on the surface facing the LED when the surface light source device is obtained, good quality can be ensured.
As a marking method, laser, ink jet, stamp roller, pen, and the like can be considered. In this production example, ink jet is suggested. As the ink material for inkjet, a dye system or a pigment system can be selected. However, in consideration of bleeding, the pigment system is often preferable. Moreover, water, an organic solvent (MEK, ethanol) etc. can be considered as a solvent. In the case of water, since there is no volatile substance, it is effective as a countermeasure against volatile organic compound VOC (Volatile Organic Compounds). If the organic solvent is taken into consideration for VOC countermeasures, the drying time is fast, so that the processing time can be shortened, and the organic solvent can be properly used as necessary.

(Marking for single sheet)
Moreover, it may be difficult to perform marking from the state of a roll by some processing methods, such as the above-mentioned manufacturing method B and the manufacturing method D mentioned later. FIG. J10 illustrates the marking method in that case. In step D3, sheets to be marked are sequentially sent out toward the marking head, and marking is performed on both ends of the sheet. The object of marking shown is the slit slit peeled half-slit longitudinal groove sheet (sheet) J42, but this device can mark the longitudinal groove sheet J3 with adhesive, the half-slit sheet J4, etc. as necessary. Can also be used. Various combinations of the processing steps are possible, and the fifth invention of the specification is not limited only to the processing flow shown in the manufacturing example.
In addition, as a marking method for a single sheet, a manual pen method can be used by using a jig or the like (a ruler, a mask, etc.) for aligning positions. When the production volume is small, it is possible to select manual operation.

(Half slit processing method C3 and B3 to a single wafer sheet)
A method for half-sliting the marked longitudinal groove sheet J31 manufactured in the process B2 of the manufacturing method B or the process C2 of the manufacturing method C to form the marking-equipped half-slit sheet J41 will be described with reference to FIG.
The flute sheet J31 with marking manufactured in the process C2 or the flute sheet J31 with marking that has undergone the marking processing on the single wafer through the process B2 is peeled off from the feed stage on the front and back sides. Set to be a separator. The flute sheet with marking J31 is fed to the place where it is placed under the single blade on the feed stage, and the depth from which the heavy peel separator does not break while reaching the heavy peel separator to the width corresponding to the thickness of the light guide plate Then, a half slit sheet (sheet) J41 with marking can be manufactured.

(Slit white peeling process) Process C4
At this time, one sheet of adhesive-attached fluted seal J5 (hereinafter also referred to as "strip") made by the first slit and a strip made by the last slit are sent out to one fluted sheet J31 with marking. Since it is influenced not only by the feed accuracy of the stage but also by the setting position accuracy of the longitudinal groove sheet J31 with marking, it is not easy to make the width to maintain the optical performance corresponding to the thickness of the light guide plate. For this reason, FIG. J7 illustrates a method of removing strips at both ends of a half slit sheet (sheet) J41 with marking.
The technique is generally performed manually, but can be mechanized and peeled off. In this way, the half slit sheet (sheet) J43 with the marking slit peeled off can be manufactured. This form is packed in a plurality of bags and cardboard packed, and transported to a step of bonding to the light incident surface of the light guide plate or sold to a manufacturer for bonding to the light incident surface of the light guide plate.

(Number of strips at half slit)
When half slits are inserted in the process shown in Fig. J6, the number of half slits increases because the strip is driven in the slit insertion start direction (left direction in Fig. J6) on the sheet by the thickness of the blade. When coming, the strip may float greatly from the heavy release separator, or the strip may ride on the adjacent strip. In addition, it is better that the number of strips per sheet is larger in consideration of packing efficiency. From the above two restrictions, the number of strips on the slit slit peeled half slit sheet (sheet) J41 or the marking slit slit half peel sheet (sheet) J43 is preferably 10 or more and 100 or less, 25 The number is more preferably 75 or more and 75 or less, and 50 is the most preferable in the industry, which is a sharp number in view of inventory management.

(Slit white width)
The width of the slit white is set for the purpose of improving the accuracy of the strip width and for preventing the strip from being peeled off from the half slit sheet (sheet) J4 by friction or the like during packing or transportation. However, if the width of the slit white is made too large, the taking efficiency deteriorates. Considering such a problem, the width of the slit white needs to be about 0 mm or more and 20 mm or less, preferably 1 mm or more and 10 mm or less, more preferably 2 mm or more and 5 mm or less. Further, if the width of the strip is equal to the thickness of the corresponding light guide plate, it is preferable because it can be easily manufactured without changing the feed conditions of the feed stage in FIG. For example, a strip width of 2.8 mm is suitable for a 3 mm-thick light guide plate that is mainly used for televisions in the market. In this case, the slit white is about 3 mm ± 1.5 mm in consideration of processing accuracy. It is preferable to set.

(Manufacturing method D1 of half-slit small roll) Rotary die method As described above, the strip length that can exist as a product (various types of light incident surface of the light guide plate) is very many, and the thickness of the light guide plate Since some types are limited to some extent, if you keep the state of the small roll with half slit (half slit small roll J222) as an intermediate stock, you will receive an order for the required strip length size In this case, it will be possible to handle delivery in a very short period of time, which has a great industrial significance.
The method will be described with reference to FIG. Unroll the fluted sheet roll small roll J221 with adhesive material and press the rotary blade provided with a cylinder-shaped blade over the circumference to insert the half slit while flowing the roll seamlessly (step D1-1). ). Thereafter, the slit white portion is removed from the end of the sheet (step D1-2). Thereafter, the longitudinal groove layer is taken up as an inner side, and a half slit small roll J222 can be manufactured (winding step).

(Half slit roll roll cutting method D2 and marking method D3)
A method of manufacturing a half slit sheet (sheet) J43 with a marking slit peeled off from the half slit roll J222 will be described.
As shown in Fig. J9, the half slit small roll J222 is unwound and cut and sheeted according to the length of the light incident surface of the light guide plate with a single blade (process D2). A slit longitudinal groove sheet (sheet) J42 can be manufactured. Depending on the assembly process of the light guide plate, the marking may not be necessary. Therefore, it is preferable that a plurality of sheets are packed in this form and transported or sold.
Then, as illustrated in FIG. J10, the slit slit peeled half-slit longitudinal groove sheet (sheet) J42 is set on the delivery stage with the longitudinal groove layer as the front and the heavy release separator layer as the back, and the stage is fed. In accordance with the above, a marking line is made near the edge of the sheet. In this way, a half slit sheet (sheet) J43 with a marking slit peeled off can be manufactured.

(Half slit sheet warping direction)
The half slit sheet J4 is finally manufactured on the premise that the longitudinal groove seal J5 with adhesive is individually peeled from the heavy release separator in the bonding step to the light incident surface of the light guide plate. A preferred warping direction of the half slit sheet J4 assuming that will be described with reference to FIG. J11.
In FIG. J11, the longitudinal groove layer is set as a convex side so as to warp on the convex side in a cross section perpendicular to the direction in which the half slit is formed. In this way, as shown in the enlarged cross-sectional view, it is possible to set a tendency for the plurality of adhesive-attached fluted seals J5 to be separated so as to be slightly opened. It is easy to peel off and is very suitable. In addition, it is possible to minimize the concern that the adhesive material may be re-welded (stringing failure) when exposed to a high temperature or the like with the slit surface of the adhesive material in contact.
This warpage can be controlled by the pressing depth using the slit depth inserted into the heavy release separator or the roll in each processing step.

(Slit depth reaching the heavy release separator)
So far, the method of performing half slitting by means such as a single blade or a rotary die has been exemplified. FIG. J12 illustrates a suitable depth J6 where the slit extends to the heavy release separator.
As shown in FIG. J12, the slit direction is set substantially perpendicular to the ridge line of the longitudinal groove of the longitudinal groove layer and substantially perpendicular to the surface of the separator. In order to surely slit to the adhesive layer, it is preferable to insert slits J6 of 0 μm or more into the heavy release separator, and it is necessary to keep the heavy release separator to a depth at which it does not break. In consideration of the stable production in consideration of the accuracy of the half slitting apparatus and the strength at which the heavy release separator is not broken by handling or the like, the slit depth J6 reaching the heavy release separator is preferably 2 μm or more and less than half the thickness of the heavy release separator, More preferably, it is 5 μm or more and 25 μm or less.

(Slit and strip misalignment over heavy release separator)
In FIG. J13 and FIG. J14, the form which was suitable by controlling the shift | offset | difference of the slit J6 and the strip J5 which reach the heavy peeling separator mentioned above is illustrated.
In FIG. J13, the left cross section of the sheet is manufactured such that the slit J6 extending to the heavy release separator and the strip J5 are largely displaced. In step B3 or step C3, this can be realized by inserting a half slit from the left in FIG. J13 and controlling the angle of the blade edge of one blade. Specifically, there is a method of making the blade angle asymmetric. In this way, the longitudinal groove seal (strip) J5 with adhesive is removed from the heavy release separator by manufacturing the adhesive longitudinal groove seal (strip) J5 and the slit J6 extending to the heavy release separator. The risk of the heavy release separator breaking together when peeling individually is greatly reduced.
Moreover, in FIG. J14, the suitable shift | offset | difference at the time of processing by the rotary die method D1 shown in FIG. J8 is illustrated. Due to the nature of the rotary blade, the gap between the slit J6 and the strip J5 reaching the heavy release separator to some extent near the center is small, but in order to minimize the risk of breakage of the heavy release separator, the strip J5 on the left and right on FIG. Is manufactured outside the gap. This can be realized by changing the angle of the rotary blade individually in the length direction of the cylinder.
In addition, as shown in FIG. J13 and FIG. J14, a plurality of adhesive-attached longitudinal groove seals can be produced by trying to manufacture the adhesive-attached longitudinal groove seal (strip) J5 and the slit J6 extending over the heavy release separator. (Stripes) It is possible to prevent the problem of riding on the J5 and to stabilize the entire manufacturing process.

(An alternative to marking)
In this production example, the description of the marking has been described above as a visible mark. Instead of the above, it is also possible to select a method in which a colored protective film is bonded to the entire surface or a part of the longitudinal groove surface and formed integrally with the adhesive longitudinal groove seal J5. The former applies heat to the light guide plate after bonding. The latter peels only the colored protective film after bonding the adhesive-attached longitudinal groove seal J5 on the light incident surface of the light guide plate. If these methods are used, no marking remains on the light incident surface.

  In this production example, the invention has been described by limiting to a specific form within the scope of the purpose of explaining the invention. However, the present invention is not limited to the configuration, and can be appropriately combined and changed.

(Adhesive material)
In the present production example, the adhesive layer has been described with a thickness of 25 μm. However, in the fifth specification, the present invention is not limited to this thickness. A thickness of 5 μm or more and 250 μm or less is suitable. If the thickness is too thin, problems such as reliability are likely to occur. However, a thicker adhesive layer may be selected because air may not enter easily in the bonding process to the light incident surface of the light guide plate. In consideration of the circumstances, it is more preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 60 μm or less.

(Heavy release separator)
In this production example, the heavy release separator has been described with PET having a thickness of 75 μm, but in the specification 5th invention, it is not limited to this thickness. The material can be selected as long as it is a film-like member such as PC, PP, TAC, COP, PS, PMMA, MS, paper, and resin-coated paper. Further, the thickness needs to be 10 μm or more in order to insert a half slit, but the upper limit depends on the cost and the thickness that can be wound. In consideration of the circumstances around this, 10 μm or more and 500 μm or less is realistic, 25 μm or more and 250 μm or less is preferable, and 35 μm or more and 100 μm or less is more preferable. Further, 37 μm, 50 μm, and 75 μm are most suitable from the generally available PET base materials in terms of production stability and cost.

(Vertical groove layer and vertical groove sheet roll)
In this production example, the longitudinal groove layer has been described as a UV-cured resin layer having a longitudinal groove having a thickness of 15 μm, and the base material has been described as having a thickness of 125 μm of PET. It is not something. A transfer method using a thermosetting resin, a thermoplastic resin, or the like can be selected as the longitudinal groove layer, and optical materials such as PC, PP, TAC, COP, PS, PMMA, and MS can be used as the base material. Any film-like member having transparency that can be used for applications can be selected. As for the thickness of the base material, it can be implemented if it has a thickness of 10 μm or more. However, if it is too thin, handling at the time of bonding to the light incident surface of the light guide plate is poor, and workability is poor. This is not preferable because the risk of boarding increases. Therefore, in consideration of cost and performance, the thickness is preferably 25 μm or more and 250 μm or less, more preferably 38 μm or more and less than 150 μm, and most preferably 50 μm or more and 125 μm or less.

Specific embodiments of the half slit sheet that can be used in the fifth invention of the specification are as follows.
[1]
A half slit sheet in which a plurality of strip-like optical films integrated with an adhesive material are formed on a separator film,
On the surface of the optical film, there are a plurality of recesses or projections having an anisotropic shape that is long in the direction perpendicular to the side of any of the half slit sheets, or the bottom or bottom of the recess or projection. The back surface side of the optical film layer is substantially flat and an adhesive layer is integrally formed, and the separator film faces the surface facing the plane and the adhesive layer so that the adhesive layer can be easily peeled off. The optical film layer and the adhesive layer are cut in parallel with substantially the same width so as to form a plurality of strips on the separator film, and the cut direction is different from the plurality of recesses or projections. Half slit sheet that is oriented perpendicular to the long axis of the isotropic shape.
[2]
The half slit sheet according to [1], wherein at least one marking is applied to all of the plurality of strip-shaped optical films.
[3]
The half slit sheet according to the above [2], wherein the marking is applied in a line shape, and the thickness of the line is in the range of 50 μm to 2 mm.
[4]
The half slit sheet according to [2] or [3], wherein the marking is applied in a range of 1 mm to 5 mm from a short side end of the plurality of strip-shaped optical films.
[5]
The half slit sheet according to any one of [2] to [4], wherein the color of the marking is black or gray.
[6]
The size of the short side of the plurality of strip-shaped optical films is larger than the portion of the separator films on which the plurality of strip-shaped optical films are placed, and the separator film is set to have a protruding portion. The half slit sheet according to any one of the above [1] to [5], wherein
[7]
The half slit sheet according to [6], wherein a protruding portion of the separator film is set in a range of 1 mm to 5 mm.
[8]
Any one of the above [1] to [7], wherein the separator film has partial slits having a depth of 2 μm or more and half or less of the thickness of the separator film, the number of the plurality of strip-like optical films plus one. The half slit sheet according to crab.
[9]
The half slit sheet according to [8], wherein the position of the partial slit in the separator film is partially or entirely deviated from the position of the boundary between the strip-shaped optical films.
[10]
The half slit sheet according to [9], wherein the shift increases as the distance increases with the strip-shaped optical film near the center in the plane of the half-slit sheet or the strip-shaped optical film near either end.
[11]
Any one of the above [1] to [10], wherein the cross-section in the short side direction of the strip-shaped optical film warps the surface on which the strip-shaped optical film is placed, or is warped on the convex. The described half slit sheet.
[12]
The half slit sheet according to any one of [1] to [11], wherein the plurality of concave portions or convex portions having the anisotropic shape has a longitudinal groove structure.
[13]
The manufacturing method of the light-guide plate which bonds the strip-shaped optical film peeled from the half slit sheet in any one of said [1]-[12] to the light-incident surface at least 1 sheet.
[14]
The television receiver which has a light-guide plate as described in said [13].
[15]
A surface light source device having the light guide plate according to [13].

Hereinafter, a specific production example will be described.
The present invention is not limited to the above-described embodiment and the following manufacturing examples, and can be implemented with various modifications.
For example, the material, arrangement, shape, and the like of the members in the manufacturing examples are illustrative and can be implemented with appropriate changes. Further, the television receiver and the surface light source device can be configured by appropriately combining the configurations shown in the manufacturing examples. In addition, various modifications can be made without departing from the scope of the present invention.

<Production Example A>

[Production Example A-1]
The light incident surface is a mirror surface, and light scattering processing is uniformly applied to the opposite surface (circular diffusive dots made of diffusing beads and a binder having a diameter of 0.8 mm to 1.3 mm have a pitch of 2.55 mm × 1.5 mm. In a staggered arrangement (in a triangular lattice pattern), at the same distance from the end on the light incident surface side, the diameters of the dots in the partial area facing the LED and the dots in the partial area facing the LED are the same. (With a uniform dot density) light guide plate model (material: polymethyl methacrylate, thickness: 3.0 mm, width: 500 mm, length: 100 mm), LED (light emitting surface size: 4.5 mm) (Width direction) × 2.5 mm (thickness direction, 10 LEDs) are arranged along the light incident surface so that the arrangement pitch P is 27.5 mm, and a (light ray tracing simulation model of the surface light source device is produced. Shi It was.
A measurement model similar to the measurement detection model of a two-dimensional color luminance meter typified by Konica Minolta CA2000A is produced, and 7 mm inside (P / G = 3. Light Tools (Optical Research Associates) version 7. The luminance distribution when viewed from the front direction (V = 0 °, H = 0 °) in the direction equivalent to 3.93) is observed in a direction parallel to the light incident surface. 1 was used for calculation. [Production Example A-2]
The light guide plate model is subjected to light scattering processing on the opposite surface as shown in FIG. 19 (ρ = 18.0% to 45.0 in the vicinity of the light incident surface (region near 7 mm inside (G = 7 mm) from the light incident surface side end). % In the central portion of the facing surface, except that it is uniform at ρ = 8%). The luminance distribution when observed from the front direction (V = 0 °, H = 0 °) was calculated.
[Production Example A-3]
The light guide plate model is a transparent double-sided polyethylene terephthalate film with an average thickness of 125 μm on which the groove structure having the surface profile shown in FIG. 2 (average pitch: about 6 μm, average depth: about 4 μm) is formed. From the front direction (V = 0 °, H = 0 °) 7 mm inward from the light incident surface side end of the light exit surface, except that the adhesive sheet was used for attachment. The luminance distribution when observed was calculated.
[Production Example A-4]
The light guide plate model is a transparent double-sided polyethylene terephthalate film with an average thickness of 125 μm on which the groove structure having the surface profile shown in FIG. 2 (average pitch: about 6 μm, average depth: about 4 μm) is formed. Adhering using an adhesive sheet, the light scattering processing of the opposing surface is shown in FIG. 19 (ρ = 18.0% in the vicinity of the light incident surface (region near 7 mm inside (G = 7 mm) from the light incident surface side end). ˜45.0%, variation is uniform at ρ = 8% in the central portion of the opposing surface), in the same manner as in Production Example A-1, on the light incident surface side end of the light exit surface The luminance distribution when observed from the front direction (V = 0 °, H = 0 °) inside 7 mm from the top was calculated.

The luminance distribution when observed from the front direction (V = 0 °, H = 0 °) 7 mm inside from the light incident surface side end of the light exit surface of the surface light source devices of Production Examples A-1 to A-4 is shown in FIG. The standard deviation (SD value) is shown in FIG. 21 and Table A-1.
In FIG. 20, the vertical axis represents luminance, and the horizontal axis represents the position in the direction parallel to the light incident surface on the light exit surface. Further, in FIG. 21, the chain line indicates an S.D. allowable for use in an image display device. D. Value (0.2), and the alternate long and short dash line is sufficient S.D. D. The value (0.1) is shown.

[Table A-1]

In the surface light source device of Production Example A-1, the luminance is not constant and a hot spot (maximum portion) appears, and even in the surface light source devices of Production Examples A-2 and 3, this luminance unevenness cannot be resolved. . That is, the light configured such that the light scattering degree of the partial area directly facing the point light source is lower than the light scattering degree of the partial area directly facing the portion between the point light source and the light incident surface of the opposing surface. In Production Example A-2 subjected to scattering processing, the luminance of the portion directly facing the LEDs could be suppressed, but the luminance of the portion directly facing between the LEDs could not be increased. On the other hand, in Production Example A-3 in which a groove structure was formed on the light incident surface of the light guide plate, the luminance of the portion directly facing between the LEDs could be suppressed to some extent, and the luminance of the portion corresponding to between the LEDs could be increased. It wasn't.
On the other hand, in the surface light source device of Production Example A-4, the luminance was almost constant regardless of the location, and no hot spot appeared.
The surface light source device of Production Example A-4 is not provided with a frame and the light emitting area is not defined. However, in order to achieve a display device with a narrow frame that is currently in trend, G (light incident surface) In the surface light source device (P = 27.5 mm) of Production Example A-4, 7 mm from the light incident surface side end of the light exit surface is required. S. of luminance when observed from the front direction on the inside. D. The value was very low at 0.04. Therefore, even if the LED array pitch is expanded to about 30 mm under the condition of G = 7 mm, that is, P / G> 4, it is acceptable for use in an image display device as long as it is observed from the front direction. S. D. The value (0.2) is considered to be obtained. However, in the surface light source device of Production Example A-4, the light scattering degree of the partial region directly facing the point light source is 7 mm inside (area corresponding to the light emitting area) from the light incident surface side end of the opposing surface of the light guide plate. Since it is lower than the light scattering degree of the partial region directly facing the portion between the point light source and the point light source (ρ1 = 18.0%, ρ2 = 45.0%), the oblique direction (V = 0 °, H = 20 °) ) Of the luminance as measured from D. The calculated value was 0.05 or more. Therefore, when the LED array pitch is widened, the allowable S.D. D. The value may not be obtained.

[Production Example A-5]
A polyethylene terephthalate film having an average thickness of 125 μm and having a groove structure having the surface profile (average pitch: about 6 μm, average depth: about 4 μm) shown in FIG. Attached and subjected to light scattering processing shown in FIG. 30 on the opposite surface (circular diffusive dots made of diffusing beads and a binder having a diameter of 0.8 mm to 1.3 mm in a staggered arrangement (in a triangular lattice shape) ), Ρ = 20 to 60% in a partial region directly facing between the point light source and the point light source of 1 to 4 mm (light shielding portion, region B in the vicinity of the light incident surface) from the end portion on the light incident surface side, 4 mm or more from the light incident surface side end portion (non-light shielding portion, region A) so that ρ = 7 to 20% in the light incident surface side end portion 4 to 6 mm (light shielding portion (boundary area), region A). ) Is set so that ρ = 8%. A) Light guide plate (material: polymethyl methacrylate, thickness: 3.0 mm, width: 409 mm, length: 721 mm), LED (light emitting surface size 5.0 mm (width direction) × 3.0 mm (thickness direction), LED (Several 36) were arranged along the light incident surface so that the arrangement pitch P was 19.2 mm.
On top of this, from the light guide plate side, a diffusion sheet (DS), a prism sheet (having a groove structure having a ridge line parallel to the light incident surface on which the LED is disposed on the surface), and a reflective polarizing sheet (manufactured by 3M) DBEF) is laminated in this order, and a frame having an opening of 395 mm × 700 mm in a size that sufficiently covers the light guide plate and the LED is arranged on the light guide plate so as to face the light output surface side of the light guide plate. A light source device was produced.
Using a secondary color luminance meter (CA2000A manufactured by Konica Minolta), the luminance is measured from the front direction (V = 0 °, H = 0 °) of the light emitting surface, and the standard deviation (SD value) of the luminance of the light emitting surface is calculated. Asked.
The results are shown in FIG. The luminance S.D. D. The value was as very low as 0.02 or less in P / G = 1 to 2.6 (G is a distance (mm) from the light incident surface).

Further, when the light emitting surface is viewed from an oblique direction (V (Vertical) = 45 ° or H (Horizontal) = 20 °) (the measurement direction of the luminance meter is V = 45 ° or H = 20 with respect to the front surface of the light emitting surface). (Measured at an angle of inclination), the luminance S.D. D. Values are shown in Table A-2. Here, H and V indicate the inclination angles of the luminance meter, and the inclination angles in directions parallel to the light incident surface (inclination angles rotated around an axis perpendicular to the light incident surface), the light incident surface, respectively. Is a direction in which a positive value falls at the center of the light emitting area or the display area at an inclination angle in a direction perpendicular to (an inclination angle rotated about an axis parallel to the light incident surface).
In the surface light source device of Production Example A-5, not only from the front, but also luminance unevenness when viewing the light exit surface from an oblique direction was reduced. In addition to the measurement using a two-dimensional color luminance meter, the luminance unevenness is also evaluated in parallel with the visual evaluation. D. It was confirmed that the result was the same as the result of the value.

[Table A-2]

[Production Example A-6]
The light scattering processing of the opposing surface of the light guide plate was as shown in FIG. 32 (circular diffusive dots having a diameter of 0.8 mm to 1.3 mm made of diffusion beads and a binder in a staggered arrangement (in a triangular lattice shape) Ρ = 20 to 60% in the partial region facing directly between the point light source and the point light source of 1.5 to 4.5 mm (light shielding portion, region B in the vicinity of the light incident surface) from the light incident surface side end. In addition, 4.5 mm to 6 mm from the light incident surface side end (light shielding portion (boundary area), region A) is 6 mm or more from the light incident surface side end (non-light shielding) so that ρ = 10 to 13%. In the part, region A), ρ = 8 to 9% is provided, and when compared with the light scattering processing in Production Example A-5, between the partial region directly facing the point light source in the boundary area and between the point light source and the point light source Except for the small difference in the light scattering degree of the partial region directly facing to the same as in Production Example A-5, It was observed uneven brightness of the light plane.
The luminance unevenness was observed in Production Example A-5 when observed from either the front (V = H = 0 °) or the oblique direction (V = 0 °, H = 20 °, V = 45 °, H = 0 °). It was smaller than that.

[Production Example A-7]
In the surface light source device of Production Example A-6, a display panel having a configuration similar to that shown in FIG. ) Was arranged so as to face the light exit surface side of the light guide plate, and a display device was manufactured, and luminance unevenness in the display area was observed.
The luminance unevenness in the display area is a manufacturing example even when observed from either the front (V = H = 0 °) or the oblique direction (V = 0 °, H = 20 °, V = 45 °, H = 0 °). It was smaller than that of A-5.

[Production Example A-11]
A polyethylene terephthalate film having an average thickness of 125 μm and having a groove structure having the surface profile shown in FIG. 24C is attached to the light incident surface using a transparent double-sided adhesive sheet, and the light scattering shown in FIG. 33 is applied to the opposite surface. Processed (circular diffusive dots of 0.8 mm to 1.3 mm in diameter consisting of diffusing beads and a binder in a staggered arrangement (in a triangular lattice shape), 1.5 to 3 from the light incident side end .5 mm (light-shielding portion, region B in the vicinity of the light incident surface) of the partial region directly facing between the point light source and the light source surface side end portion so that ρ = 20 to 60%. 5 to 6 mm (light-shielding part (boundary area), region A) is ρ = 10%, and ρ = 9% is 6 mm or less (non-light-shielding part, region A) from the light incident surface side end. From the end of the light incident surface. .5 mm (no light scattering processing is provided in other regions including the light shielding portion, region C)) on the light guide plate (material: polymethyl methacrylate, thickness: 3.0 mm, width: 409 mm, length: 721 mm), The LEDs (light emitting surface size 5.0 mm (width direction) × 3.0 mm (thickness direction), 36 LEDs) were arranged along the light incident surface so that the arrangement pitch P was 19.2 mm.
On this, from the light guide plate side, a diffusion sheet (DS) / prism sheet (having a groove structure having a ridge line perpendicular to the light incident surface on which the LED is disposed on the surface) / prism sheet (the LED is disposed) (A groove structure having a ridge line parallel to the light incident surface is provided on the surface) / diffusion sheet (DS) is laminated in this order, and further, the outer shape sufficiently covers the light guide plate and the LED and is 395 mm × A frame having an opening of 700 mm is disposed so as to face the light exit surface side of the light guide plate, a surface light source device is manufactured, and the luminance distribution S.D. of the light exit surface is manufactured in the same manner as in Production Example A-5. D. The value was determined.
Further, a liquid crystal display panel is laminated on the surface light source device, and the luminance distribution S.D. D. Values were also determined.
The results are shown in FIG.

  The luminance unevenness is 0.01 or less in the front (V = H = 0 °) and 0.01 or less in the oblique direction (V = 45 °, H = 0 °), and the oblique direction (V = 0 °, H = 20 °), which was 0.01 or less, even when observed from any of these, it was even smaller than that of Production Example A-6.

In Production Example A-11, in addition to the light scattering processing of the light exit surface, there is a prism sheet (having a groove structure on the surface having a ridge line perpendicular to the light entrance surface on which the LED is disposed) as an optical sheet. The brightness unevenness reduction effect can be obtained very strongly, and when viewed from an oblique direction by adding a prism sheet (having a groove structure having a ridge line parallel to the light incident surface on which the LED is arranged) on the surface Further improvement in luminance unevenness was also obtained.
Moreover, the light scattering process provided in the light guide plate was not visually recognized by the diffusion sheet disposed between the light guide plate and the prism sheet.

[Production Example A-12]
The light scattering processing of the opposite surface of the light guide plate was as follows (not shown) (circular diffusive dots made of diffusing beads and a binder having a diameter of 0.8 mm to 1.3 mm in a staggered arrangement (triangular lattice) ) = Ρ = 50 in a partial region directly facing a portion between the point light source and the point light source of 1.5 to 3.5 mm (light shielding portion, region B in the vicinity of the light incident surface) from the light incident surface side end. In the range from 4.5 to 6 mm from the light incident surface side end so as to be ˜100% (light shielding portion (boundary area), region A), from the light incident surface side end so that ρ = 10%. After 6 mm (non-light-shielding part, area A), ρ = 9% is provided, and other areas including 3.5 to 4.5 mm (light-shielding part, area C) from the end of the light incident surface are provided. Except that light scattering processing is not provided), luminance unevenness on the light exit surface was observed in the same manner as in Production Example A-5.
Even when the luminance unevenness was observed from either the front or the oblique direction, a quality better than that of Production Example A-6 was obtained.

  In Production Example A-12, since the prism sheet used was only one sheet having a groove structure having a ridge line parallel to the light incident surface on which the LEDs are arranged, the luminance unevenness reducing effect is Although not as good as in Production Example A-11, substantially the same effect was obtained.

[Production Example A-13]
The LED arrangement pitch P was changed to 13.4 mm, and the light scattering processing of the opposing surface of the light guide plate was as follows (not shown) (with a diameter of 0.8 mm to 1.3 mm consisting of diffusion beads and a binder) The circular diffusive dots are arranged in a staggered arrangement (in a triangular lattice pattern) with a point light source and a point light source of 1.5 to 3.5 mm (light shielding portion, region B in the vicinity of the light incident surface) from the light incident surface side end. In the partial region directly facing the intermediate portion (width 4.5 mm), 4.5 to 6 mm (light-shielding portion (boundary area), region A) from the light incident surface side end so that ρ = 50 to 100%. Is provided so that ρ = 9% after 6 mm from the light incident surface side end portion (non-light-shielding portion, region A) so that ρ = 10%, and light scattering processing is performed in other regions. In the same manner as in Production Example A-5, the luminance distribution S.D. D. The value was determined.
Even when the luminance unevenness was observed from either the front or the oblique direction, a quality better than that of Production Example A-6 was obtained.
The results are shown in FIG.

  In Production Example A-13, since the prism sheet used was only one sheet having a groove structure having a ridge line parallel to the light incident surface on which the LEDs are arranged, the luminance unevenness reducing effect is Although not as good as in Production Example A-11, the pitch between point light sources was suppressed more than in Production Example A-11, and almost the same effect was obtained.

[Production Examples A-14 to 16]
In the 32ML10 type television receiver manufactured by Mitsubishi Electric Corporation, the arrangement pitch of LEDs in the surface light source device is changed to 19.2 mm, and the light guide plate is subjected to light scattering processing shown in Table A-3 on the opposite surface (FIG. A1 or FIG. 33), and instead of the reflective sheet bonded to the side surface (side surface perpendicular to the light incident surface) shown in Table A-3 (FIGS. A11 to A13), Production Example A-14 ( Television receivers a) to (d) were produced.
On the light incident surface of the light guide plate, a polyethylene terephthalate film having an ultraviolet curable resin layer having a plurality of recesses (FWHM: 83 (width) × 3 (length)) shown in FIG. Television receivers of Production Examples A-15 (a) to (d) were produced in the same manner as in Production Example A-14 except that they were bonded together using PD-S1 manufactured by Panac.
On the light incident surface of the light guide plate, a polyethylene terephthalate film having a prism with apex angle R (pitch: about 50 μm: the ridge line direction of the prism coincides with the thickness direction of the light guide plate) on the surface is a transparent double-sided adhesive sheet (PD-made by Panac) Except having bonded together using S1), it carried out similarly to manufacture example A-14, and produced the television receiver of manufacture example A-16 (a)-(d).
For these television receivers, the in-plane average luminance of the secondary color luminance meter (CA2000A manufactured by Konica Minolta) and the in-plane average chromaticity x and y were measured through a liquid crystal panel. The (a) no unevenness was used as a reference, the luminance was relative luminance%, and the chromaticities x and y were arranged as differences Δx and Δy from the reference. The results are shown in Tables A-3 to 5 below.

[Table A-3]

[Table A-4]

[Table A-5]

In Production Examples A-14 to 16, the light scattering pattern on the opposite surface of the light guide plate may be the one shown in FIG. A1 or the one shown in FIG. As long as the arrangement of the reflection sheet and the shape of the light incident surface) were the same, there was no significant difference in luminance and chromaticity.
Moreover, when it has a several recessed part or convex part in the light-incidence surface of a light-guide plate (manufacture example A-15), in-plane average compared with the case where a light-incidence surface is a mirror surface (manufacture example A-14) Although the brightness tends to decrease, the average brightness could be recovered by applying a reflective sheet to the entire side surface of the light guide plate (arrangement of FIG. A11). In addition, when the reflective sheet is partially attached to the side surface of the light guide plate, the average in-plane is more likely to be applied in the vicinity of the light incident surface as shown in FIG. The brightness could be increased.

[reference]
In a system in which the pitch of LEDs is denser (P = 10.0 mm), light scattering processing is applied to a region A that covers at least a non-light-shielding portion that is not shielded by a light-shielding frame on the light exit surface and / or the opposing surface of the light guide plate. In addition, in the region B in the vicinity of the light incident surface of the light shielding part that is shielded by the light shielding frame, the light scattering degree of the partial region that directly faces the point light source is a partial region that faces the part between the point light source and the point light source. In a region C that is subjected to light scattering processing configured to be lower than the light scattering degree and is sandwiched between the region A and the region B, at least a partial region that faces at least a portion between the point light source and the point light source If light scattering processing is not provided in the case, even if a plurality of concave portions or convex portions are not formed on the light incident surface (even if the light incident surface is a substantially mirror surface), a certain degree of luminance unevenness reduction effect is obtained. can get.
Conventionally, in the region A, a light guide plate has been proposed in which the light scattering degree of the partial region facing the point light source is higher than the partial region facing the point light source, but the oblique quality in the H direction is particularly poor. The optimum quality for TV etc. could not be obtained. Further, in the region A, the partial region directly facing the point light source and the partial region directly facing between the point light source and the point light source have the same light scattering degree, and in the region B, the portion facing directly between the point light source and the point light source. It is a specification in which light scattering processing is performed only on the region, and even when the region C is not provided and the region A and the region B are in contact, the quality in the H direction is not sufficient.
Luminance unevenness on the light exit surface was observed in the same manner as in Production Example A-11 except that a film having a groove structure was not pasted on the light entrance surface of the light guide plate and the LED array pitch P was 10 mm.
Even when observed from the front or oblique direction, the luminance unevenness is a light guide plate in which a film having a groove structure formed on the light incident surface is not pasted by light scattering processing as shown in FIG. Compared to a light guide plate that does not have a groove structure on the light surface and is not subjected to light scattering processing corresponding to the position of the point light source).

<Production Example B>

(Diffusion sheet)
In Production Example B, using a master mold having a predetermined speckle pattern, the photopolymerizable resin composition is filled between the substrate and the master mold, and cured through ultraviolet irradiation through the substrate. Next, it was made to peel between the master type | mold and the resin layer which consists of hardened | cured material of a photopolymerizable resin composition, and the resin layer which has an uneven structure was formed in the single side | surface of a base material.
Production Examples B-1 to 6, 9, and 10 all used the same master mold.
In addition, Production Examples B-7 and 8 are different from the master type in which the diffusion angle differs depending on the projection area immediately above the light source and the projection area between the light sources, as will be described later, and Production Examples B-7, 8 A master mold with a different distribution shape was used.
In the ultraviolet irradiation, irradiation was performed using a high-pressure mercury lamp with an irradiation condition of 250 mJ / cm ² .
The thickness of the resin layer was 15 μm.

(Various optical sheets used in Production Example B)
Reflective sheet: White reflective sheet made of polyester resin (hereinafter abbreviated as “RS”, trade name: Lumirror E6SL, manufactured by Toray)
Diffusion plate: Diffusion plate made of polystyrene and having a thickness of 1.5 mm and a diffusing agent concentration of 13000 ppm (hereinafter abbreviated as “DP”, trade name DSF60, manufactured by Asahi Kasei E-Materials)
Surface-shaped diffusion sheet: An optical sheet (hereinafter abbreviated as “MLF”) in which a hemispherical lens is shaped with a UV curable resin on a PET substrate having a thickness of 250 μm. Product name: PTR-733, manufactured by Shinfa Intertec )
Optical sheet having an arrayed prism array structure: an optical sheet in which a prism array having a vertex angle of 90 ° and a pitch of 50 μm is formed by a UV curable resin on a PET substrate having a thickness of 250 μm (hereinafter referred to as “prism sheet”) (Product name: BEF-III, 3M)
Reflective polarizing sheet: reflective polarizing sheet (hereinafter abbreviated as “DBEF”, trade name DBEF, manufactured by 3M)
Were used respectively.

(Light source and light source unit used in Production Example B)
As a light source of the light source unit, a white LED light source (trade name: LM6-EWN1-03-N3 manufactured by CREE) having a 3.5 mm square and a height of 2.0 mm was used.
133 LEDs were arranged and arranged in a pattern as shown in FIG. B17 to produce a light source unit.

Hereinafter, a method for measuring characteristics in Production Example B will be described.
(Diffusion angle)
The diffusion angle is made incident from the surface of the diffusion sheet having a fine concavo-convex structure, and manufactured by Photon Co., Ltd. Goniometric Radiometers Real-Time Far-Field Angular Profiles Model LD89.
Measured at 00.
In Production Example B below, for example, when the diffusion angle is expressed as 5 °, it indicates that the FWHM (diffusion angle) of light in any direction is also 5 °.
For the diffusion angle distribution, FWHM was measured at intervals of 1 mm with respect to the x-axis direction and / or the y-axis direction of the diffusion sheet, and a diffusion angle distribution diagram was created.

(Brightness and brightness unevenness)
The luminance was determined by using a two-dimensional color luminance meter (CA2000) manufactured by Konica Minolta, installed 70 cm away from the light source unit, and an average luminance value measured in a range of 120 mm × 120 mm at the center of the light source unit as luminance.
The luminance unevenness was an average value of values calculated in two directions of the x-axis direction and the y-axis direction.
First, an average luminance value in the x-axis (120 mm) direction is obtained, and in the y-axis direction, luminance is obtained as a standard deviation of a value obtained by dividing the luminance value at each point by the average luminance value for ± 15.2 mm from each point. I asked for unevenness.
Similarly, the average luminance value in the y-axis (120 mm) direction is obtained, and the standard deviation of the value obtained by dividing the luminance value at each point by the luminance average value for ± 20.8 mm from each point in the x-axis direction. Luminance unevenness was obtained.
Finally, a value obtained by averaging the standard deviation in the x-axis direction and the standard deviation in the y-axis direction (hereinafter, <Production Example B>
Inside, it is expressed as “SD”. ) Is the luminance unevenness of the light source unit.
Since the LED light source is a point light source, the diffusion angle distribution is considered on a line (a broken line in FIG. 2B (b)) where the linear distance between adjacent light sources is the maximum, as shown in FIG. B2 (b). .
The brightness unevenness was measured from the normal direction to the screen.
Here, the criteria for determining the luminance unevenness were classified into two stages (◯, ×) as follows.
○: S. D. ≦ 0.005
X: 0.005 <S. D.

(Refractive index of resin layer)
The refractive index of the resin layer was measured by removing the resin layer having a thickness of 15 μm from the substrate and measuring only the resin layer with a refractometer MODEL 2 010 PRISM COUPLER (manufactured by Metricon).
The measurement results are shown in Table B-1 below for each resin used.

[Production Example B-1]
As shown in FIG. B14 (b), above the light source (LED) 12, a diffusion plate (DP) 14, a diffusion sheet 15, a prism sheet 17, a reflective polarizing sheet (DBEF) 18 of Production Example B-1, which will be described later, Were arranged in this order to obtain a light source unit of Production Example B-1.
The diffusion sheet 15 of Production Example B-1 is formed on one surface of a base material of a polyethylene terephthalate film (Cosmo Shine A4300, manufactured by Toyobo Co., Ltd., hereinafter referred to as “PET base material”) having a thickness of 250 μm. The resin layer (resin 1) which consists of a hardened | cured material of the photopolymerizable resin composition which has a composition shown to Table B-1 and Table B-2 is formed, and this resin layer has a speckle pattern by interference exposure on the surface. It has an irregular concavo-convex structure derived from
In Tables B-1 and B-2, (A-1) to (A-5) correspond to “(A): addition polymerizable monomer having at least one terminal ethylenically unsaturated group”. Among them, (A-1) corresponds to the compound represented by the above general formula (I). (B-1) corresponds to (B): a photopolymerization initiator.
This diffusion sheet 15 was used so that the concavo-convex structure surface was the light exit surface.
The diffusion angle (FWHM) of the diffusion sheet 15 of Production Example B-1 was 83 °.
Here, the distance h between the reflection sheet (RS) 13 and the light incident surface of the diffusion plate (DP) 14 was set to 21.0 mm.
The luminance unevenness in the light source unit of Production Example B-1 was calculated by the above method.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-2]
The photopolymerizable resin composition was changed to (Resin 2) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-2 was 85 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-3]
The photopolymerizable resin composition was changed to (Resin 3) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-3 was 90 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-4]
The photopolymerizable resin composition was changed to (Resin 4) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-4 was 80 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-5]
The photopolymerizable resin composition was changed to (Resin 5) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-5 was 87 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-6]
The photopolymerizable resin composition was changed to (Resin 6) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-6 was 86 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-7]
As shown in FIG. B14 (a), above the light source 12, a diffusion plate (DP) 14, a diffusion sheet 15 of Production Example B-7 to be described later, a surface shaping type diffusion sheet (MLF) 16, a surface shaping type. A diffusion sheet (MLF) 16 and a reflective polarizing sheet (DBEF) 18 were arranged in this order to constitute the light source unit of Production Example B-7.
The diffusion sheet of Production Example B-7 comprises a cured product of a photopolymerizable resin composition having a composition shown in Table B-1 and Table B-2 below on one surface of a PET substrate having a thickness of 250 μm. It has a resin layer (resin 1), and the resin layer has an irregular uneven structure derived from a speckle pattern by interference exposure on the surface.
In the diffusion sheet of Production Example B-7, the diffusion angle of the projection area of the light source is 83 °, the diffusion angle of the projection area of the intermediate point between the light source and the light source is 28 °, and the diffusion angle is as shown in FIG. changed.
In addition, the horizontal axis of FIG. B18 (a) shows the predetermined position on the diffusion sheet surface, and the round mark described in the horizontal axis shows the position of the light source.
The diffusion sheet of Production Example B-7 was used so that the layer on which the irregular concavo-convex pattern shape was formed became the light exit surface.
Here, the distance h between the reflection sheet (RS) 13 and the light incident surface of the diffusion plate (DP) 14 was set to 19.0 mm.
The luminance unevenness in the light source unit of Production Example B-7 was calculated by the above method.
The evaluation results of the luminance unevenness are shown in Table B-3 below.
Moreover, all the measurement points distributed between the arithmetic mean value (Av1) of the diffusion angle peak value and the diffusion angle bottom value in the diffusion sheet of Production Example B-7, and the continuous diffusion angle peak value and the diffusion angle bottom value. Table B-3 below shows the arithmetic average value (Av2) of the diffusion angles.

[Production Example B-8]
As shown in FIG. B14 (a), a diffusion plate (DP) 14 above the light source 12, a diffusion sheet 15 of Production Example B-8 to be described later, a surface shaping diffusion sheet (MLF) 16, a surface shaping diffusion. The sheet (MLF) 16 and the reflective polarizing sheet (DBEF) 18 were arranged in this order to constitute the light source unit of Production Example B-8.
The diffusion sheet of Production Example B-8 is composed of a cured product of a photopolymerizable resin composition having a composition shown in Table B-1 and Table B-2 below on one surface of a PET substrate having a thickness of 250 μm. The resin layer (resin 1) was provided, and the resin layer had an irregular uneven structure derived from a speckle pattern by interference exposure on the surface.
In the diffusion sheet of Production Example B-8, the diffusion angle of the projection region of the light source is 83 °, the diffusion angle of the projection region of the intermediate point between the light source and the light source is 28 °, and the diffusion angle is as shown in FIG. B18 (b). changed.
Note that the horizontal axis in FIG. B18 (b) indicates a predetermined position on the diffusion sheet surface, and the circles described in the horizontal axis indicate the position of the light source.
The diffusion sheet of Production Example B-8 was used so that the layer provided with the irregular concavo-convex pattern shape was the light exit surface.
Here, the distance h between the reflection sheet (RS) 13 and the light incident surface of the diffusion plate (DP) 14 was set to 17.0 mm.
The luminance unevenness in the light source unit of Production Example B-8 was calculated by the above method.
The evaluation results of the luminance unevenness are shown in Table B-3 below.
Further, all measurement points distributed between the arithmetic average value (Av1) of the diffusion angle peak value and the diffusion angle bottom value in the diffusion sheet of Production Example B-8, and the continuous diffusion angle peak value and the diffusion angle bottom value. Table B-3 below shows the arithmetic average value (Av2) of the diffusion angles.

[Production Example B-11]
The photopolymerizable resin composition was changed to (Resin 7) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-11 was 75 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-12]
The photopolymerizable resin composition was changed to (Resin 8) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-12 was 70 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Table B-1]

[Table B-2]

[Table B-3]

As shown in Table B-1, the diffusion sheets of Production Examples B-1 to B-6 are diffusion sheets having a resin layer having an uneven structure on the light exit surface of the diffusion sheet, and the refractive index of the resin layer is 1.55. To 1.70, and the resin is (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group: 70 to 99.9% by mass, (B) photopolymerization initiator: 0.1 A cured product of a photopolymerizable resin composition containing -30% by mass, wherein the (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group is represented by the general formula (I) Since the compound which has a structure represented is contained, the brightness nonuniformity reduction capability was favorable and it turned out that the distance between a light source and an optical sheet can be shortened.
Moreover, although it is usually difficult to obtain a diffusion sheet having a diffusion angle (FWHM) of 76 ° or more, if the above-mentioned photopolymerizable resin composition is used, the transfer rate is reduced due to curing shrinkage or the cured product is too hard. It has been found that it is possible to obtain a diffusion sheet that can be achieved without causing defects due to the above, and that has a good ability to reduce uneven brightness.

Moreover, since the diffusion angle of the diffusion sheet of Production Example B-7 periodically changes along a predetermined direction in the diffusion sheet surface, the luminance unevenness reduction ability is better, and the reflection sheet (RS) 13 and It was found that the distance h from the light incident surface of the diffusing plate (DP) 14, that is, the distance between the light source and the optical sheet can be further shortened.
Further, in the diffusion sheet of Production Example B-8, all the measurement points distributed between the diffusion angle peak value and the diffusion angle bottom value in which the arithmetic average value (Av1) of the diffusion angle peak value and the diffusion angle bottom value continues. Is larger than the arithmetic average value (Av2) of the diffusion angle, and thus the luminance unevenness reduction capability is very good, and the distance h between the reflection sheet (RS) 13 and the light incident surface of the diffusion plate (DP) 14, that is, the light source It was found that the distance between the optical sheet and the optical sheet can be further shortened.

<Production Example C>

[Production Example C-1]
The light incident surface is a mirror surface, and light scattering processing is uniformly applied to the opposite surface (circular diffusive dots made of diffusing beads and a binder having a diameter of 0.8 mm to 1.3 mm have a pitch of 2.55 mm × 1.5 mm. In a staggered arrangement (in a triangular lattice pattern), at the same distance from the end on the light incident surface side, the diameter of the dots in the area facing the LED and the dots in the area facing the LED are the same ( Light guide plate model (material: polymethyl methacrylate, thickness: 3.0 mm, width: 500 mm, length: 100 mm) provided on LED (light emitting surface size 4.5 mm (width)) Direction) × 2.5 mm (thickness direction, 10 LEDs) was prepared along a light incident surface so that a light tracing simulation model of a surface light source device was arranged so that the arrangement pitch P was 27.5 mm.
A measurement model similar to the measurement detection model of a two-dimensional color luminance meter typified by Konica Minolta CA2000A is produced, and 7 mm inside (P / G = (Corresponding to 3.93) was calculated using Light Tools (Optical Research Associates) version 7.1 over a direction parallel to the light incident surface.
[Production Example C-2]
C19 (rho1 = 18.0%, ρ2 = 45.0% in the vicinity of the light incident surface (near 7 mm inside (G = 7 mm) near the light incident surface side end) of the light guide plate model. The brightness distribution 7 mm inside from the light incident surface side end of the light exit surface was calculated in the same manner as in Production Example C-1 except that the above was changed.
[Production Example C-3]
The light guide plate model is a transparent double-sided polyethylene terephthalate film with an average thickness of 125 μm on which the groove structure having the surface profile shown in FIG. 2 (average pitch: about 6 μm, average depth: about 4 μm) is formed. A luminance distribution 7 mm inward from the light incident surface side end of the light exit surface was calculated in the same manner as in Production Example C-1, except that the adhesive sheet was used.
[Production Example C-11]
The light guide plate model is a transparent double-sided polyethylene terephthalate film with an average thickness of 125 μm on which the groove structure having the surface profile shown in FIG. 2 (average pitch: about 6 μm, average depth: about 4 μm) is formed. Attaching using an adhesive sheet, the light scattering processing of the opposite surface is shown in FIG. C19 (rho1 = 18.0%, rho2 = near the light incident surface (near 7 mm inside (G = 7 mm) near the light incident surface side end)) 45.0%) A luminance distribution 7 mm inside from the light incident surface side end of the light exit surface was calculated in the same manner as in Production Example C-1.

The luminance distribution 7 mm inside from the light incident surface side end of the light exit surface of the surface light source devices of Production Examples C-1 to C3 and 11 is shown in FIG. C20, and its standard deviation (SD value) is shown in FIG. Show.
In FIG. C20, the vertical axis represents luminance, and the horizontal axis represents the position in the direction parallel to the light incident surface on the light exit surface. In FIG. C21, a chain line indicates an SD value (0.2) that is acceptable for use in an image display device, and a one-dot chain line indicates an SD value (0.1) that is sufficient for use in an image display device. ing.

[Table C-1]

In the surface light source device of Production Example C-1, the luminance is not constant, and a hot spot (maximum part) appears, and even in the surface light source devices of Production Examples C-2 and 3, this luminance unevenness cannot be resolved. . That is, in Production Example C-2 in which the light scattering degree of the area facing the light source on the opposite surface is lower than the light scattering degree of the area facing the portion between the light sources Although it was possible to suppress the luminance of the portion facing the LEDs, it was not possible to increase the luminance of the portion facing the LEDs. On the other hand, in Production Example C-3 in which the groove structure was formed on the light incident surface of the light guide plate, the luminance of the portion directly facing between the LEDs could be suppressed to some extent, and the luminance of the portion corresponding to between the LEDs could be increased. It wasn't.
On the other hand, in the surface light source device of Production Example C-11, the luminance was almost constant regardless of the location, and no hot spot appeared.
Further, in order to achieve a narrow-frame display device that is currently in trend, it is necessary to set G (horizontal distance between the light incident surface and the display area) to about 7 mm. In the surface light source device (P = 27.5 mm), the SD value of the luminance 7 mm inside from the light incident surface side end of the light exit surface was as extremely low as 0.04. Therefore, the light incident surface of the light guide plate has a plurality of concave portions or convex portions, and the opening portion or the bottom surface thereof has a plurality of concave portions or convex portions having a long anisotropic shape in a direction perpendicular to the light emitting surface. The light scattering degree of the area facing the light source is lower than the light scattering degree of the area facing the portion between the light sources on the light exiting surface and / or the opposing surface of the light guide plate. In the surface light source device configured to have the light scattering processing, even if the LED array pitch is expanded to about 30 mm under the condition of G = 7 mm, that is, P / G> 4, at least the image It is believed that an SD value (0.2) acceptable for use in a display device is obtained.

[Reference Experiment C1]
The optimum values of light scattering processing and frame overlap were investigated.
Take out the surface light source device part (the one with the opening starting from the position corresponding to 8 mm inside from the light incident surface end of the light guide plate) from the commercially available LED TV (BRAVIA EX710 manufactured by Sony Corporation), The light incident surface is a mirror surface, and the opposite surface is 2 mm, 6 mm, or 10 mm from the end of the light incident surface. What was applied uniformly (with uniform dot density) in a staggered arrangement with a pitch of 2.55 mm × 1.5 mm (ie, the overlap between the frame and the light scattering process was 6 mm, 2 mm or − 2 mm (without overlap)) or a groove structure on the light incident surface in the same manner as in Production Example C-11, and 2 mm, 6 mm, or 10 m from the light incident surface side end on the opposite surface The in-plane average luminance of the light emitting area was measured in place of the light scattering process from m.
FIG. C22 shows values obtained by dividing the in-plane average luminance of the light-emitting areas of these surface light source devices by the input power (value obtained by correcting variations in luminance efficiency and input power).
From FIG. C22, the in-plane average brightness is reduced if there is no overlap between the light scattering process and the frame. On the other hand, the in-plane average brightness is reduced even if the overlap is too large. It was confirmed that it was preferable.

[Reference Experiment C2]
A ray tracing simulation model 1 of the same surface light source device as in Production Example C-11, and a simulation model 2 and a simulation model 3 in which the LED array pitch P was changed to 22.5 mm and 25 mm were prepared.
Using these simulation models 1 to 3, using Light Tools (Optical Research Associates) version 7.1, the luminance distribution at the inner side (G = 7 mm) 7 mm from the light incident side edge of the light exit surface of the light guide plate The light in the region directly facing the dot density ρ1 of the light scattering processing pattern in the region facing the light source near the light incident surface and the portion between the light source near the light incident surface and the light source, where the SD value is less than 0.2. When the combination of the dot density ρ2 of the scattering pattern was calculated, the following results were obtained.
When the results are plotted with ρ2 / ρ1 as the vertical axis and P / G as the horizontal axis, linearity (ρ2 / ρ1 = 1.4 × (P / G) −3.0) as shown in FIG. C23 is recognized. It was. Thereby, if ρ1 and ρ2 are adjusted so that ρ2 / ρ1 satisfies the following relational expression, it is possible to realize an outgoing light distribution without luminance unevenness at a desired P / G.
2.9 ≦ 1.4 × (P / G) −ρ2 / ρ1 ≦ 3.1

[Table C-2]

[Standard Reference C]
The arrangement pitch P of LEDs is 10.5 mm, and the horizontal distance G between the light incident surface of the light guide plate (material: polymethyl methacrylate, thickness: 4 mm) and the display area is 16.5 mm (P / G = 0.64). From the commercially available LED TV (BRAVIA KDL-32EX700 manufactured by Sony Corporation), only the surface light source device part is taken out, and the LEDs are rearranged so that the LED arrangement pitch is about 42 mm (P / G = 2.55) The luminance at the position 16.5 mm inside (corresponding to the display area start portion) from the light incident surface side edge of the light exit surface of the light guide plate and further 10 mm inside (26.5 mm inside from the light incident surface side edge) is obtained. Measurement was performed using a two-dimensional color luminance meter (CA-2000) manufactured by Konica Minolta.

[Production Example C-21]
In the above surface light source device, a polyethylene terephthalate film having an average thickness of 125 μm and having the groove structure of the present invention formed on the light incident surface of the light guide plate is pasted using a transparent double-sided adhesive sheet (CS9621T manufactured by Nitto Denko Corporation). The luminance at a position 26.5 mm inside from the light incident surface side end of the light exit surface was measured. The groove structure has the surface profile shown in FIG. 2 manufactured by speckle pattern exposure, and the average pitch is about 6 μm and the average depth is about 4 μm.

[Production Examples C-31 to 33]
In the surface light source device, the light guide plate was replaced with the following, and the luminance at a position 26.5 mm inside from the light incident surface side end of the light exit surface was measured. As with the light guide plate of Production Example C-21, each of the light guide plates is made of a polyethylene terephthalate film having a predetermined microstructure and an average thickness of 125 μm on the light incident surface of the standard reference light guide plate. It was manufactured by sticking using
Manufacture example C-31: Light guide plate having a prism with a 90 ° apex angle (pitch: about 50 μm) on the light entrance surface Production example C-32: Light guide plate having a lenticular lens (pitch: about 120 μm) on the light entrance surface C-33: Light guide plate having prisms with apex angle R (pitch: about 50 μm) on the light incident surface

A variation in luminance of the surface light source device using the manufacturing example and the light guide plate of the standard reference C is shown in FIG. In FIG. C3-13, the vertical axis indicates the luminance at a position 26.5 mm inside from the light incident surface side end of the light exit surface, and the horizontal axis indicates the position in the width direction of the light incident surface of the light guide plate.
In the surface light source device of Production Example C-21, the luminance was almost constant regardless of the location, and no hot spot appeared. On the other hand, in the case of using a light guide plate (standard reference C) used in a commercial television or a light guide plate corresponding to the light guide plate disclosed in the prior art documents (Production Examples C-31 to 33). The brightness was not constant, a hot spot (maximum part) appeared, and the brightness unevenness could not be solved.

<Production Example D>

In the following Production Examples D-1 to 17, 42, and 43, an ultraviolet curable resin layer in which a vertically long or isotropic depression having the surface shape of FIGS. 24A to 24J is formed on the light incident surface of the light guide plate. It manufactured by sticking the base material which consists of a polyethylene terephthalate film which has this using a transparent double-sided adhesive sheet (PD-S1 by a Panac company).
The diffusion angle, the average pitch of the recesses, the average depth of the recesses, and the substrate thickness of the films of FIGS.

[Table D-1]

[Reference 1]
The arrangement pitch P of LEDs is 10.5 mm, and the horizontal distance G between the light incident surface of the light guide plate (material: polymethyl methacrylate, thickness: 4 mm) and the display area is 16.5 mm (P / G = 0.64). From the commercially available LED television (BRAVIA KDL-32EX700 manufactured by Sony Corporation), only the surface light source device part was taken out, and the LEDs were rearranged so that the LED array pitch P was about 21 mm.
A diffusion sheet (installed in BRAVIA KDL-32EX700 manufactured by Sony Corporation) is disposed on the light exit surface side of the light guide plate, and at a position 1 m from the normal direction of the light exit surface, a two-dimensional color luminance meter manufactured by Konica Minolta ( CA-2000) was installed and the luminance of the light exit surface was measured.

[Evaluation of luminance unevenness suppression ability]
From the light emission surface luminance data measured by the two-dimensional color luminance meter (CA-2000), the distance G from the light incident surface side end of the light emission surface is 20 mm, 25 mm, 30 mm, 35 mm and 40 mm (light incident Luminance profiles were extracted in a direction parallel to the light incident surface (in the direction (A) in FIG. 9) 20 mm, 25 mm, 30 mm, 35 mm, and 40 mm inside from the surface side end.
In order to cancel the luminance gradient unrelated to the hot spot from each of the luminance profiles L (X) (X axis: distance in the direction parallel to the light incident surface, Y axis: luminance L), the LED pitch P (in this case) Is a value smoothed by taking an average value in a range corresponding to about 21 mm) (moving average value)

And a standard deviation value (SD value) obtained by dividing the luminance profile by the moving average value of the luminance profile was obtained and used as an index of luminance unevenness, that is, hot spot by the LED.
A graph in which P / G (P = 21 mm, G = 20, 25, 30, 35, 40 mm) is taken on the X axis and the standard deviation value (indicator of luminance unevenness) is taken on the Y axis is shown in FIG. D17.

[Evaluation of achievement]
In order to cancel the uneven brightness of the hot spot, the brightness profile in the light propagation direction (direction (B) in FIG. 9) from the brightness data of the light exit surface measured by the two-dimensional color luminance meter (CA-2000). The average value T (X ′) of L (X) in the range of ± 1.5 P (P is the LED pitch) from the central LED in the evaluation range in the direction parallel to the light incident surface (A direction in FIG. 9). ) Was calculated and plotted with the distance in the direction perpendicular to the light incident surface (direction B in FIG. 9) as the X ′ axis and the Y axis as T (X ′) (FIG. 16). In this luminance profile, a shielding plate for fixing the light guide plate is installed in the range (X = 0 to 16.5 mm) from the light incident surface of the light guide plate to the inside of 16.5 mm. Is zero. Next, X = 16.5 mm to 390 mm of this luminance profile was extracted.

[Production Example D-1]
In the surface light source device of Reference 1, a polyethylene terephthalate film having an average thickness of 250 μm and having a groove structure to be described later formed on the light incident surface of the light guide plate is pasted using a transparent double-sided adhesive sheet (PD-S1 manufactured by Panac Corporation). Except for the above, a luminance profile in the direction parallel to the light incident surface of the light exit surface was measured in the same manner as in Reference 1, and the luminance unevenness was obtained.
The groove structure has the surface profile shown in FIG. 24A manufactured by speckle pattern exposure, and has an average pitch of about 7.3 μm and an average depth of about 2.5 μm. Moreover, the diffusion angle (FWHM) when measured using GC-5000L in the state of the film alone was 47 ° × 4 °.
Similarly to the reference 1, X = 16.5 to 390 mm are extracted from the luminance profile in the light propagation direction, and the ratio of the luminance value to the reference 1 for each measurement point included in this range (each measurement The value obtained by dividing the luminance value of the point by the luminance value at the same location (X) of the reference 1) was determined, and the minimum value (MIN) and the maximum value (MAX) were listed in Table D-2.

[Production Example D-2]
In the surface light source device of Reference 1, a polyethylene terephthalate film having an average thickness of 100 μm and having a groove structure described later formed on the light incident surface of the light guide plate is pasted using a transparent double-sided adhesive sheet (PD-S1 manufactured by Panac Corporation). Except for the above, a luminance profile in the direction parallel to the light incident surface of the light exit surface was measured in the same manner as in Reference 1, and the luminance unevenness was obtained.
Further, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured in the same manner as in Reference 1, and the values of MIN and MAX were obtained in the same manner as in Production Example D-1.
The groove structure has the surface profile shown in FIG. 24B manufactured by speckle pattern exposure, and has an average pitch of about 5.4 μm and an average depth of about 3.6 μm. Moreover, FWHM when measured using GC-5000L in the state of the film alone was 63 ° x 1 °.

[Reference 2]
Except for setting the LED arrangement pitch P to about 31.5 mm, the luminance unevenness suppressing ability and the reach were evaluated in the same manner as in Reference 1.
[Production Example D-3]
Reference 2 except that a polyethylene terephthalate film having an average thickness of 250 μm and having the same groove structure as in Production Example D-1 formed on the light incident surface of the light guide plate was attached using the same transparent double-sided adhesive sheet as in Production Example D-1. In the same manner as described above, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured to determine the luminance unevenness.
Similarly to Reference 2, the luminance profile in the light propagation direction (the direction perpendicular to the light incident surface) is measured, and MIN and MAX are the same as in Production Example D-1, except that the reference is set to Reference 2. The value was determined.
[Production Example D-4]
Reference 2 except that a polyethylene terephthalate film having an average thickness of 100 μm and having the same groove structure as in Production Example D-2 formed on the light incident surface of the light guide plate was attached using the same transparent double-sided adhesive sheet as in Production Example D-2.
In the same manner as described above, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured to determine the luminance unevenness.
Similarly to Reference 2, the luminance profile in the light propagation direction (the direction perpendicular to the light incident surface) is measured, and MIN and MAX are the same as in Production Example D-1, except that the reference is set to Reference 2. The value was determined.

[Reference 3]
Except for setting the LED arrangement pitch P to about 42 mm, the luminance unevenness suppressing ability and the reach were evaluated in the same manner as in Reference 1.
[Production Example D-5]
Reference 3 except that a polyethylene terephthalate film having an average thickness of 250 μm and having the same groove structure as in Production Example D-1 formed on the light incident surface of the light guide plate was attached using the same transparent double-sided adhesive sheet as in Production Example D-1. In the same manner as described above, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured to determine the luminance unevenness.
Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.
[Production Example D-6]
Reference 3 except that a polyethylene terephthalate film having an average thickness of 100 μm and having the same groove structure as in Production Example D-2 formed on the light incident surface of the light guide plate was attached using the same transparent double-sided adhesive sheet as in Production Example D-2. In the same manner as described above, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured to determine the luminance unevenness.
Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.

Graphs with luminance unevenness (SD values) of Production Examples D-1 to 6 as Y-axis and P / G as X-axis are shown in FIGS.
Table 2 summarizes the evaluation results of the degree of achievement (MIN, MAX).

FIGS. D17A, B, and C compare the performance differences of the light guide plates by aligning conditions other than the shape of the light incident surface (LED pitch P of the surface light source device). From any of the figures, it can be confirmed that the manufacturing examples D-1 to 6 have smaller luminance unevenness than the reference. Further, when P / G is small as in FIGS. D17A and D17B, there is a difference between the reference and the manufacturing example, but there is almost no difference between the manufacturing examples. (Furthermore, when P / G is 1 or less, the luminance unevenness is originally small, so the difference between the manufacturing example and the reference is also small.) Compared to Example D-5 (surface shape in FIG. 24A (the vertical diffusion angle is 47 °)), Production Example D-6 (surface shape in FIG. 24B (the vertical diffusion angle is 63 °)) )) Is better performance.
FIGS. D17D, E, and F compare the cases where the LED pitch P is changed using the same light guide plate. From these figures, in the light guide plate of Production Example D as well as the reference, the same performance (luminance unevenness reduction performance) is obtained as long as P / G is the same value even if the LED arrangement pitch P is changed. Can be confirmed.

[Table D-2]

  Looking at the degree of achievement (MAX, MIN), the films of Production Examples D-1, 3, 5 are generally better.

In the subsequent production examples, the same LED arrangement as that of the reference 3 was adopted, and the luminance unevenness and the reach were evaluated in the same manner as in the reference 3 [Production Examples D-7 to 11].
A film was prepared in which longitudinal grooves having an angle of −10 °, −5 °, 0 °, 5 ° or 10 ° with respect to the thickness direction of the light guide plate were formed on a polyethylene terephthalate film having an average thickness of 125 μm. In the same manner as in Reference 3, except that the above film was attached to the light incident surface of the light guide plate using a transparent double-sided adhesive sheet (PD-S1 manufactured by Panac Co., Ltd.). A luminance profile was measured to determine luminance unevenness.
Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.
The groove structure has the surface profile of FIG. 24C manufactured by speckle pattern exposure, and the average pitch is about 6.6 μm and the average depth is about 3.4 μm. Moreover, FWHM when measured using GC-5000L in the state of the film alone was 83 ° x 3 °.
The suppression ability of Production Examples D-7 to 11 is shown in FIG. D18, and the reach (MIN, MAX) is shown in Table D-3.

[Table D-3]

  Even when the direction of the longitudinal groove was changed in the range of −10 ° to 10 °, the luminance unevenness suppressing ability (FIG. D18) and the degree of achievement (Table D-3) did not change significantly.

[Production Examples D-12 to 15, 12 ′ to 15 ′]
Reference 3 except that the same film as the film having the groove structure of Production Example D-1 was cut to a width of 4 mm and pasted with a gap (seam) of 0 to 1.5 mm on the light incident surface. In the same manner as described above, the luminance profile in the direction parallel to the light incident surface of the light emitting surface was measured to obtain luminance unevenness.
Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.
At that time, the gap (seam) between the films does not cover the LED light emitting surface (and the facing portion) (Production Examples D-12 to 15) and the LED light emitting surface of the LED (Manufacturing) Two types of examples D-12 ′ to 15 ′) were prepared.
The luminance unevenness suppressing ability of Production Examples D-12 to 15 and Production Examples D-12 ′ to 15 ′ are shown in FIGS. D19 and D20, and the reach (MIN, MAX) is shown in Table D-4. In addition, the thing (equivalent to manufacture example D-6) which affixed the film in which the groove | channel structure was formed without cutting (without opening a clearance gap) was made into the reference 4.

[Table D-4]

  There was no significant difference in the degree of achievement (Table D-4) depending on the presence / absence and position of a gap (seam). On the other hand, with respect to luminance unevenness, when there was a gap (seam) on the LED light emitting surface, the luminance unevenness increased significantly (Fig. D19), but a gap (seam) was formed between the LED light emitting surfaces. There was no problem in performance (Fig. D20).

[Production Examples D-16, 17]
On the light incident surface of the light guide plate, a polyethylene terephthalate film having a diffusion angle (FWHM) of 83 ° × 3 ° (surface shape diagram 24C) and an average thickness of 125 μm, and a diffusion angle (FWHM) of 92 ° × 50 ° ( 24D), a polyethylene terephthalate film having an average thickness of 250 [mu] m was applied in the same manner as in Reference 3 except that the same transparent double-sided adhesive sheet as in Production Example D-1 was applied. The luminance profile in the direction parallel to the surface was measured to determine the luminance unevenness.
Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.
[Production Examples D-35, 36]
Luminance unevenness, MIN, and MAX were measured in the same manner as in Production Example D-16 or 17 except that the surface shape was rotated by 90 ° (that is, the indentation was horizontally long).
The results are shown in FIG. D21 and Table D-5.

[Table C2-5]

  In the case where the shape of the indentation was horizontally long, the luminance unevenness suppressing ability decreased (FIG. D21), and the degree of achievement (Table D-5) also deteriorated.

[Production Example D-37 to 40]
Except that the light guide plate was replaced with the following, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured in the same manner as in Reference 3, and the luminance unevenness was obtained. Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.
Each light guide plate is made of a polyethylene terephthalate film having an average thickness of 250 μm (Production Example D-38 only 400 μm) having a predetermined fine structure, as in the light guide plates of Production Examples D-1 to 6. It manufactured by sticking to the light-incidence surface of the light-guide plate using a transparent double-sided adhesive sheet (PD-S1 by Panac Co., Ltd.).
Production Example D-37: A hemisphere having a radius of 30 μm is randomly arranged on the light incident surface with an average pitch of 70.6 μm.
Production Example D-38: A prism with a 90 ° apex angle arranged on the light incident surface periodically (grating) with a pitch of about 60 μm.
Production Example D-39: A prism with apex angle R arranged on the light incident surface periodically (grating) with a pitch of about 50 μm.
Production Example D-40: A lens in which lenticular lenses are periodically arranged at a pitch of about 150 μm on the light incident surface.
The results are shown in FIG. D22 and Table D-6. For comparison, FIG. D22 and Table D-6 show a groove structure of Production Example D-6 (surface profile: FIG. 24B, average pitch: about 5.4 μm, average depth: about 3.6 μm). The data of a production example in which a polyethylene terephthalate film formed with affixed to the light incident surface was also posted.

[Table D-6]

  Production Example D-37 had poor reach, and Production Examples D-38, 39, and 40 had low suppression ability.

[Production Examples D-19 to 23] [Production Examples D-42 and 43]
Except that the light guide plate was replaced with one having the following surface shape, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured in the same manner as in Reference 3 to obtain luminance unevenness.
Production Example D-19: FIG. 24 (E)
Production Example D-20: FIG. 24A (corresponding to Production Example D-5)
Production Example D-21: FIG. 24 (G)
Production Example D-22: FIG. 24 (F)
Production Example D-23: FIG. 24 (H)
Production Example D-42: FIG. 24 (I) (isotropic depressions that are not vertically long are formed)
Production Example D-43: FIG. 24 (J) (isotropic depressions that are not vertically long are formed)
With respect to the luminance unevenness measured above, 0.020 or less was evaluated as ○, 0.020 or more and less than 0.050 as Δ, 0.050 or more as ×, and vertical FWHM (in the thickness direction of the light guide plate ( FWHM (in the plane perpendicular to the light exit surface), calculated from the transmitted light intensity cross section in the same direction as the longitudinal direction of the longitudinal groove), horizontal axis FWHM (in the plane parallel to the light exit surface) in the width direction of the light guide plate FWHM) was plotted as the vertical axis. The results are shown in FIG. D23.
Regarding the luminance unevenness suppressing ability (FIG. D23), it can be said that the lateral FWHM is preferably 60 ° or more.

  For the light guide plates of Production Examples D-19 to 22, 42 and 43, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured in the same manner as in Reference 3, and the reference was set as Reference 3. Except for the above, the values of MIN and MAX were determined in the same manner as in Production Example D-1, and the results are shown in Table D-7.

[Table C2-7]

  Taking the reach (Table D-7) into consideration, it can be said that Production Example D-17 is not an optimal shape.

<Production Example E>

[Production Example E-1A]
PMMA light guide plate (flat plate of width 400mm, length 700mm, thickness 4mm) used in Sony liquid crystal television BRAVIA 32EX700 as a base material, acrylic adhesive (laminated on release paper as adhesive layer) G ′ = 77,000 Pa (G ₀ ′ = 18,000)
00Pa)) film (PD-S1 manufactured by Panac Co., Ltd., pressure-sensitive adhesive film thickness: 25 μm, TG / DTA (weight reduction rate) at 100 ° C.−0.06%), and as a light diffusion layer, from polyethylene terephthalate A multilayer film in which a layer made of an ultraviolet curable resin having a groove structure with a diffusion angle of 60 ° × 1 ° on the surface was prepared on a transparent base film (A4300 manufactured by Toyobo Co., Ltd.) having a thickness of 125 μm.
Next, prepare two sheets each of the adhesive layer and the light diffusion layer cut to the size of the side surface in the longitudinal direction of the base material (the light diffusion layer is cut so that the direction of the diffusion angle is 60 degrees in the longitudinal direction) The adhesive layer and the light diffusing layer were adhered to both side surfaces in the longitudinal direction of the base material in this order using a roller to form a light incident part (light incident surface), and a light guide plate was produced.
Specifically, first, the pressure-sensitive adhesive film is temporarily fixed to the side surface of the base material so that the pressure-sensitive adhesive and the base material are in contact with each other. Squeezing and removing air bubbles. After that, the release film of the adhesive film is peeled off, and the light diffusion layer is temporarily fixed thereon so that the surface opposite to the surface having the concavo-convex structure is in contact with the adhesive, and from one end of the substrate side surface. The other end of the concavo-convex structure was squeezed with a roller and pasted.
One diffusion sheet (TDF187 manufactured by Toray Sehan Co., Ltd.) is laminated on one main surface of the light guide plate produced as described above, and 18 pieces (9 on each light incident surface) along the light incident surface. ) Were arranged substantially evenly so that the arrangement pitch was 42 mm (distance between the LED and the light incident surface: 0.8 mm), and a surface light source device was produced.
Using a two-dimensional color luminance meter (CA-2000) manufactured by Konica Minolta, the brightness at a position corresponding to the inner side 10 mm from the light incident surface side end on the diffusion sheet laminated on the light guide plate is turned on. It was measured along the longitudinal direction of the light guide plate. The obtained luminance profile is shown in FIG. E17.

[Production Example E-1B]
A surface light source device was prepared in the same manner as in Production Example E-1A, except that the light diffusion layer was not used as an adhesive layer, and only both ends were fixed with a 4 mm square adhesive tape and laminated on both side surfaces in the longitudinal direction of the base material. A luminance profile 10 mm inside from the end of the light incident surface was measured. The obtained luminance profile is shown in FIG. E18.

  In the surface light source device of Production Example E-1A in which the light diffusion layer was fixed to the base material via the adhesive layer, the luminance was substantially constant along the longitudinal direction of the light guide plate, but the production without using the adhesive layer In the surface light source device of Example E-1B, the luminance unevenness in the longitudinal direction of the light guide plate was severe.

[Production Example E-2A]
A base plate made of PMMA LX N865 manufactured by Mitsubishi Rayon Co., Ltd., having a width of 30 mm, a length of 250 mm and a thickness of 4 mm, and an acrylic pressure-sensitive adhesive (G ′ = 77,000 Pa) laminated on a release paper as an adhesive layer (G ₀ ′ = 18,000 Pa)) film (PD-S1, manufactured by Panac Corporation, pressure-sensitive adhesive film thickness: 25 μm, peel strength: 0.75 N / mm), and a light diffusion layer having a thickness of 125 μm On the base film polyethylene terephthalate (A4300 manufactured by Toyobo Co., Ltd.) layer, a multilayer film having a layer made of an ultraviolet curable resin having a fine concavo-convex structure on its surface was prepared.
Next, the adhesive layer and the light diffusing layer are cut to the size of the side surface in the longitudinal direction of the base material, and the light is incident on one side of the base material in the longitudinal direction by adhering the adhesive layer and the light diffusing layer in this order using a roller. The light guide member was produced. Specifically, first, the pressure-sensitive adhesive film is temporarily fixed to the side surface of the base material so that the pressure-sensitive adhesive and the base material are in contact with each other. Squeezing and removing air bubbles. After that, the release film of the adhesive film is peeled off, and the light diffusion layer is temporarily fixed thereon so that the surface opposite to the surface having the concavo-convex structure is in contact with the adhesive, and from one end of the substrate side surface. The other end of the concavo-convex structure was squeezed with a roller and pasted.

[Production Example E-2B]
A light guide plate was produced in the same manner as in Production Example E-2A except that the thickness of the transparent base film layer of the light diffusion layer was changed to 250 μm.
[Production Example E-2C]
A light guide plate was produced in the same manner as in Production Example E-2A except that the thickness of the substrate was changed to 3.5 mm.
[Production Example E-2D]
A light guide plate was produced in the same manner as in Production Example E-2C except that the thickness of the transparent base film layer of the light diffusion layer was changed to 250 μm.
[Production Example E-2E]
Acrylic pressure-sensitive adhesive (G ′ = 84,000 Pa (G ₀ ′ = 19,800 Pa)) film (TR-1801A manufactured by Fujimori Kogyo Co., Ltd., pressure-sensitive adhesive film thickness) laminated on release paper. A light guide plate was produced in the same manner as in Production Example E-2A, except that TG / DTA (weight reduction rate) -0.05% at 25 [mu] m, 100 [deg.] C.-0.05%, peel strength: 0.63 N / mm).
[Production Example E-2F]
Acrylic pressure-sensitive adhesive (G ′ = 68,000 Pa (G ₀ ′ = 16,900 Pa)) film (CCL / D1 / T3T3 manufactured by New Tack Kasei Co., Ltd., pressure-sensitive adhesive film) A light guide plate was produced in the same manner as in Production Example E-2A except that the thickness was changed to 25 μm and the peel strength was 0.61 N / mm.
[Production Example E-2G]
Acrylic pressure-sensitive adhesive (G ′ = 44,000 Pa (G ′ ₀ = 10,700 Pa)) film (EXC10-076 manufactured by Toyo Ink Co., Ltd., pressure-sensitive adhesive film thickness) laminated on the release paper. A light guide plate was produced in the same manner as in Production Example E-2A except that the thickness was changed to 50 μm).
[Production Example E-2H]
A film (MO-3006C manufactured by Lintec Corporation) made of an acrylic pressure-sensitive adhesive (G ′ = 160,000 Pa (G ₀ ′ = 44,600 Pa)) laminated on release paper.
A light guide plate was produced in the same manner as in Production Example E-2A except that the pressure-sensitive adhesive film thickness was changed to 25 μm, TG / DTA (weight reduction rate) at 100 ° C.—0.09%.
[Production Example E-2I]
A film (MO-3012C manufactured by Lintec Corporation, pressure-sensitive adhesive film thickness) made of an acrylic pressure-sensitive adhesive (G ′ = 30,000 Pa (G ₀ ′ = 6,100 Pa)) laminated on a release paper. A light guide plate was produced in the same manner as in Production Example E-2A, except that TG / DTA (weight reduction rate) at 0.10 / 25 μm and 100 ° C. (0.10%) was changed.

In the light guide plates of Production Examples E-2A to 2I, the light diffusion layer was firmly fixed to the base material. After these light guide plates were allowed to stand under the following conditions a to d, the occurrence of peeling between the base material and the adhesive layer and between the adhesive layer and the light diffusion layer was visually observed and evaluated based on the following criteria.
(conditions)
a. 250 hours at 90 ° C. and 30% RH b. 12 hours at 100 ° C. dry c. 1000 hours under dry conditions at 100 ° C. d. 24 hours under 85 ° C dry conditions (evaluation criteria)
A: No peeling at all O: Peeling is less than 1% of the bonding area Δ: Peeling is from 1% to less than 30% of the bonding area ×: Peeling is at least 30% of the bonding area

  The results are shown in Table E1-1. In the light guide plates of Production Examples E-2A to 2H, in which the adhesive layer is composed of an adhesive with G ′ = 40,000 to 180,000 Pa, the light diffusion layer can be peeled off even when placed under high temperature (humidity) for a long time. It didn't happen much.

[Table E1-1]

[Production Example E-3A]
As a base material, a PMMA LX N865 manufactured by Mitsubishi Rayon Co., Ltd., a flat plate with a width of 30 mm, a length of 250 mm, and a thickness of 3.5 mm, an acrylic pressure-sensitive adhesive (G ′ = 77) laminated on a release paper as an adhesive layer , 000 Pa (G ₀ ′ = 18,000 Pa)) film (PD-S1 manufactured by Panac Corporation, pressure-sensitive adhesive film thickness: 25 μm), and a transparent base film having a thickness of 125 μm made of polyethylene terephthalate as a light diffusion layer (Toyobo) A multilayer film provided with a layer made of an ultraviolet curable resin having a groove structure with a diffusion angle of 60 ° × 1 ° on the surface was prepared on an A4300) layer.
Next, a laminator is used to laminate an adhesive layer on the surface of the light diffusion layer opposite to the surface having the concavo-convex structure to form a laminate, and this laminate is cut into the size of the side surface in the longitudinal direction of the substrate. The release paper of the adhesive layer was peeled off, and a light incident part was formed on one of the side surfaces in the longitudinal direction of the base material by using a roller so as to be in the order of the adhesive layer and the light diffusion layer, and a light guide plate was produced. .
One diffusion sheet (TDF187 manufactured by Toray Sehan Co., Ltd.) is laminated on one main surface of the light guide plate produced as described above, and 18 pieces (9 on each light incident surface) along the light incident surface. ) LEDs were arranged substantially evenly so that the arrangement pitch was 26 mm (distance between LED and light incident surface: 0.8 mm), and a surface light source device was produced.
Next, the LED is turned on, and using a Konica Minolta two-dimensional color luminance meter (CA-2000), the distance from the light incident surface side end on the diffusion sheet laminated on the light guide plate is X mm ( The operation of obtaining the luminance profile by measuring the luminance at the Xmm inner side from the light incident surface side end portion along the longitudinal direction of the light guide plate was repeated in increments of 1 mm for a range of X = 10 to 20 mm. Based on the brightness profile obtained in this way, the distance (X) from the light incident surface side end that can be judged to have eliminated the brightness unevenness was found to be 13 mm. [Production Example E-3B]
Similar to Production Example E-3A, except that the jig used for laminating the laminate of the adhesive layer and the light diffusion layer is changed to a spatula made of polypropylene resin. It was 14 mm when the distance (X) from was measured.
[Production Example E-3C]
Production Example E-, except that a polyethylene terephthalate film having a thickness of 250 μm was inserted between the spatula and the laminate when laminating the laminate of the adhesive layer and the light diffusion layer with a spatula (squeezed with a spatula through the film). In the same manner as in 3B, the distance (X) from the end portion on the light incident surface side where there was no luminance unevenness was measured and found to be 13 mm.

<Production Example F>

[Production Example F-11]
A polyethylene terephthalate film having an average thickness of 125 μm and having a groove structure having the surface profile (average pitch: about 6 μm, average depth: about 4 μm) shown in FIG. The light scattering processing shown in FIG. F30 was applied to the opposite surface (circular diffusive dots having a diameter of 0.8 mm to 1.3 mm made of diffusing beads and a binder were arranged in a staggered arrangement (in a triangular lattice pattern). ) Ρ1 = 0% and ρ2 = 60% from 1 to 4 mm (light shielding portion) from the light incident surface side end portion, and ρ1 = from 4 to 6 mm (light shielding portion (boundary area)) from the light incident surface side edge portion. 7%, ρ2 = 20%, light guide plate (provided to be ρ1 = ρ2 = 8% after 6 mm from the light incident surface side end portion (non-light-shielding portion)) (material: polymethyl methacrylate, thickness: 3.0mm, : 409 mm, length: 721 mm), LED (light emitting surface size 5.0 mm (width direction) × 3.0 mm (thickness direction), 36 LEDs)) The arrangement pitch P is 19.2 mm along the light incident surface. It arranged so that it might become. On top of this, a diffusion sheet, a prism sheet, and a reflective polarizing sheet (DBEF manufactured by 3M) are laminated in this order, and on top of that, an opening having a size that sufficiently covers the light guide plate and the LED is 395 mm × 700 mm. The surface light source device was produced by arranging the frame having the light guide plate so as to face the light exit surface side.
Using a secondary color luminance meter (CA2000A manufactured by Konica Minolta), the luminance is measured from the front direction (V = 0 °, H = 0 °) of the light emitting surface, and the standard deviation (SD value) of the luminance of the light emitting surface is calculated. Asked.
The results are shown in FIG. The luminance S.D. D. The value was as very low as 0.02 or less in P / G = 1 to 2.6 (G is a distance (mm) from the light incident surface).

Further, when the light emitting surface is viewed from an oblique direction (V (Vertical) = 45 ° or H (Horizontal) = 20 °) (the measurement direction of the luminance meter is V = 45 ° or H = 20 with respect to the front surface of the light emitting surface). (Measured at an angle of inclination), the luminance S.D. D. Values are shown in Table F-2. Here, H and V indicate the inclination angles of the luminance meter, and the inclination angles in directions parallel to the light incident surface (inclination angles rotated around an axis perpendicular to the light incident surface), the light incident surface, respectively. Is a direction in which a positive value falls at the center of the light emitting area or the display area at an inclination angle in a direction perpendicular to (an inclination angle rotated about an axis parallel to the light incident surface).
In the surface light source device of Production Example F-11, not only from the front but also from the front, the luminance unevenness when viewing the light exit surface from an oblique direction was reduced.

[Table F-2]

[Production Example F-12]
The light scattering processing of the opposing surface of the light guide plate is as shown in FIG. F32 (circular diffusive dots having a diameter of 0.8 mm to 1.3 mm made of diffusion beads and a binder are arranged in a staggered manner (in a triangular lattice pattern), Ρ1 = 0% and ρ2 = 60% from the light incident surface side edge portion to 1.5 to 4.5 mm (light shielding portion), 4.5 to 6 mm from the light incident surface side edge portion (light shielding portion (boundary area)) Ρ1 = 10%, ρ2 = 13%, and after 6 mm from the light incident side end (non-light-shielding portion), ρ1 = 8% and ρ2 = 9%. 11 in the same manner as in Production Example F-11 except that the difference in light scattering between the region facing the light source and the region facing the light source in the boundary area is small. Of the luminance distribution of D. The value was determined.
The luminance unevenness is observed in Production Example F-11 when observed from either the front (V = H = 0 °) or the oblique direction (V = 0 °, H = 20 °, V = 45 °, H = 0 °). It was smaller than that.

[Production Example F-13]
In the surface light source device of Production Example F-12, the frame is removed and the display panel has the same configuration as that shown in FIG. F28 (the size of the display frame 392. 4 mm × 696.4 mm) was arranged so as to face the light exit surface side of the light guide plate, a display device was created, and luminance unevenness in the display area was observed.
The luminance unevenness in the display area is a manufacturing example even when observed from either the front (V = H = 0 °) or the oblique direction (V = 0 °, H = 20 °, V = 45 °, H = 0 °). It was smaller than that of F-11.

<Production example G>

First, the evaluation method of Production Example G will be described.
1. Evaluation system (hot spot evaluation)
The following evaluation system 1 is used for Production Examples G-1 to 12 and 21 to 30, and the following evaluation system 2 is used for Production Examples G-13 to 15 and Production Examples G-31 and 32. Evaluation was performed.
Evaluation system 1
Five LEDs are arranged approximately evenly along the light incident surface of the light guide plate so that the light emitting surface of the LED is parallel to the light incident surface and the arrangement pitch is 18.8 mm (LED and light incident surface). The surface light source device was fabricated by laminating an optical sheet (described later) on the light exit surface side of the light guide plate. The external shape of the LED is 5.6 mm wide × 3.0 mm high.
Evaluation system 2
Five LEDs are arranged approximately evenly along the light incident surface of the light guide plate so that the light emitting surface of the LED is parallel to the light incident surface and the arrangement pitch is 9.4 mm (LED and light incident surface). The surface light source device was fabricated by laminating an optical sheet (described later) on the light exit surface side of the light guide plate. The external shape of the LED is 5.6 mm wide × 3.0 mm high.
Specifically, the LED is turned on, from the normal line direction of the light output surface of the optical sheet laminated on the light guide plate at a position 0.5 m from the light output surface (hot spot evaluation when viewed from the front) and from the normal direction. A Konica Minolta two-dimensional color luminance meter (CA-2000) is installed at a position 0.5 m from the light exit surface in the direction of 30 degrees obliquely (Fig. G26) (hot spot evaluation when viewed obliquely). The luminance distribution was measured. From the luminance data of the light exit surface measured by a two-dimensional color luminance meter (CA-2000), the distance from the light incident surface side end of the light exit surface is 7.5 mm (evaluation system 1), 3 mm (evaluation system) The luminance profile L (X) (X axis: distance in the direction parallel to the light incident surface, Y axis: luminance L) in the direction parallel to the light incident surface (2A direction) of 2) is extracted. did.

In order to cancel the brightness gradient unrelated to the hot spot from each brightness profile L (X), the LED pitch P (in this case, about 18.8 mm (evaluation system 1) or 9.4 mm (evaluation system 2)). Value smoothed by taking the average value in the range corresponding to (moving average value)

  In the evaluation of the standard deviation value (SD value), the range of X is the range excluding the LEDs at both ends, that is, from the position of the second LED from the end of the point light source group. The position from the end to the position of the second LED is used.

(Evaluation of bright lines)
For the bright line (see FIG. G18), the LED is turned on, and the optical sheet laminated on the light output surface of the light guide plate is visually observed from the normal direction of the light output surface and from an oblique direction of 30 degrees from the normal direction. The presence or absence was judged.
In addition, the hot spot and the bright line were specifically evaluated according to the criteria of Table G-1.

[Table G-1]

2. Method for Producing Light Guide Plate of Production Example G The light guide plates of Production Examples G-1 to 15 and Production Examples G-22, 24, 26, 28, 30, and 32 are provided on a light guide plate substrate to be described later via an adhesive layer. It produced by bonding a light-diffusion layer.
Specifically, an acrylic pressure-sensitive adhesive film (PANAC) laminated on release paper on the surface opposite to the light diffusion layer of a light diffusion sheet (which is provided with a light diffusion layer on a base film) to be described later PD-S1 manufactured by Co., Ltd., pressure-sensitive adhesive film thickness: 25 μm, storage elastic modulus G ′ at 100 ° C .: 77,000 Pa) was laminated to produce a multilayer film with an adhesive layer. Next, after slitting the multilayer film with an adhesive layer with a predetermined width, the release paper of the adhesive layer was peeled off and bonded to the light incident surface of the light guide plate using a roller, and the light diffusion layer was bonded.
Production Examples G-21, 23, 25, 27, 29, and 31 were light guide plates in which a light diffusion layer was not bonded to the light incident surface, and the light guide plate base material was used as it was.

3. Explanation of used members Next, various members used in Production Example G will be described.
A. Optical sheet The following optical sheet was used in combination with the light guide plate.
(A) Diffusion sheet (DS) TDF-187 manufactured by Toray Sehan
(A) Prism sheet: LG Electronics SOS-07H
(C) Reflective polarizing sheet (DBEF): DBEF-D400 manufactured by 3M
These optical sheets were used by being laminated on the light exit surface of the light guide plate during measurement.
In Production Examples G-1 to G-5 and Production Examples G-21 to G-24, one DS was laminated as an optical sheet on the light exit surface of the light guide plate.
In Production Examples G-6 to 8 and Production Examples G-25 and 26, the DS and Prism (the prism rows are orthogonal to the LED arrangement direction) are stacked one by one on the light output surface of the light guide plate.
In Production Examples G-10, 11, 13-15, and Production Examples G-27, 28, 31, 32, the above DS and Prism (the prism row is orthogonal to the LED arrangement direction) on the light exit surface of the light guide plate And DBEF were laminated one by one in the order.
In Production Example G-12 and Production Examples G-29 and 30, Prism (the prism rows are parallel to the LED arrangement direction) and Prism (the prism rows are orthogonal to the LED arrangement direction) on the light exit surface of the light guide plate ) And DBEF.

B. Light Guide Plate Base In Production Example G, the following A and B were used as the light guide plate base. A and B are both 3 mm thick flat plates made of PMMA, and the first surface is provided with a lenticular lens shape extending in a direction perpendicular to the light incident surface.
・ Light guide plate base material-A
The first surface (light exit surface) has a lenticular lens as shown in FIG. G20A, and the shape of the lenticular lens is 60 μm in height and 290 μm in pitch. The second surface (opposite surface) has a dot pattern (starting from the inside 3 mm from the light incident surface) provided by printing white ink.
・ Light guide plate base material-B
The first surface (light exit surface) has a lenticular lens as shown in FIG. G20B, and the shape of the lenticular lens is 80 μm in height and 290 μm in pitch. The second surface (opposite surface) has a dot pattern (started from the inside 3 mm from the light incident surface) provided by laser engraving.

C. Light Diffusion Sheet The light guide plate of some Production Examples G was prepared by adhering the following film with a light diffusion layer (light diffusion sheet) to the light guide plate substrate light incident surface.
・ Light diffusion sheet 1
On a transparent base film (A4300, manufactured by Toyobo Co., Ltd.) made of polyethylene terephthalate having a thickness of 125 μm, the first partial region and the second partial region having different light diffusion characteristics as shown in FIG. A light diffusing sheet having a light diffusing layer having a proportion equal to 50%. The light diffusing layer is UV-cured in which a plurality of recesses (grooves) having openings that are long in one direction (direction perpendicular to the longitudinal direction of the light incident surface (second direction)) are formed by speckle pattern exposure. It consists of resin hardened | cured material, and the average depth and average pitch of a recessed part differ in a 1st partial region and a 2nd partial region.
The diffusion angle of the entire light incident surface is 11 ° in the first direction and 1 ° in the second direction, and the range of emission angles with a peak intensity of 3/4 or more in the light emission pattern curve in the first direction is a normal distribution curve. The emission angle range with a peak intensity of 1/10 or more is narrower by 16% than that of the normal distribution curve (FIG. G22A (a)).
Each partial region has the following characteristics.
(First partial area)
Each of the divided areas has an equal area of 1.65 square millimeters, an anisotropic light diffusion characteristic in which the diffusion angle in the first direction is 17 °, and the diffusion angle in the second direction is 1 °, Has an average pitch of 15 μm and an average depth of 8 μm.
(Second partial area)
The area of each divided region is equal to 1.65 square millimeters, has an anisotropic light diffusion characteristic in which the diffusion angle in the first direction is 8 °, and the diffusion angle in the second direction is 1 °, Has an average pitch of 25 μm and an average depth of 5 μm.

・ Light diffusion sheet 2
On a transparent base film (A4300, manufactured by Toyobo Co., Ltd.) made of polyethylene terephthalate having a thickness of 125 μm, the first partial region and the second partial region having different light diffusion characteristics on the surface as shown in FIG. A light diffusing sheet having a light diffusing layer having a ratio of the first partial region occupied by 38% and the second partial region occupied by 62%. The light diffusion layer is an ultraviolet curable resin cured product in which a plurality of concave portions having openings that are long in one direction (direction perpendicular to the longitudinal direction of the light incident surface (second direction)) is formed by speckle pattern exposure. Consists of.
The diffusion angle of the entire light diffusing layer is 6 ° in the first direction and 1 ° in the second direction, and the range of the emission angle with a peak intensity of 3/4 or more in the light emission pattern curve in the first direction is a normal distribution curve. The range of the emission angle that is 5% narrower than that and 1/10 or more peak intensity is 40% larger than that of the normal distribution curve (FIG. G22A (b)).
Each partial region has the following characteristics.
(First partial area)
The area of each divided partial region is equal to 0.45 square millimeters, and has an anisotropic light diffusion characteristic in which the diffusion angle in the first direction is 10 ° and the diffusion angle in the second direction is 1 °, The average pitch of the recesses is 20 μm, and the average depth is 5 μm.
(Second partial area)
The area of each divided partial area is equal to 0.75 square millimeters, has an anisotropic light diffusion characteristic in which the diffusion angle in the first direction is 5 °, and the diffusion angle in the second direction is 1 °, The average pitch of the recesses is 33 μm and the average depth is 3 μm.

・ Light diffusion sheet 3
On a transparent base film (A4300, manufactured by Toyobo Co., Ltd.) made of polyethylene terephthalate having a thickness of 125 μm, the speckle pattern is uniformly exposed on the surface in one direction (perpendicular to the longitudinal direction of the incident surface) as shown in FIG. A light diffusing sheet having a light diffusing layer made of an ultraviolet curable resin cured product in which a plurality of concave portions having openings having a long shape in the direction (second direction) is formed.
The diffusion angle of the entire light diffusion layer is 16 ° in the first direction and 1 ° in the second direction, and the range of the emission angle with a peak intensity of 3/4 or more in the light emission pattern curve in the first direction is a normal distribution curve. The range of the emission angle that is 8% larger than that and 1/10 or more of the peak intensity is 6% larger than that of the normal distribution curve (FIG. G22A (c)).
The average pitch of the recesses is 5.2 μm, and the average depth is 1.2 μm.
・ Light diffusion sheet 4
On a transparent base film (A4300, manufactured by Toyobo Co., Ltd., made of polyethylene terephthalate) with a thickness of 125 μm, uniformly on the surface by speckle pattern exposure (direction perpendicular to the light incident surface longitudinal direction (second direction)) A light diffusing sheet having a light diffusing layer made of an ultraviolet curable resin cured product in which a plurality of recesses having long openings are formed.
The diffusion angle of the entire light diffusion layer is 14 ° in the first direction and 1 ° in the second direction, and the range of the emission angle with a peak intensity of 3/4 or more in the light emission pattern curve in the first direction is a normal distribution curve. The range of the emission angle that is 12.5% smaller than that and 1/10 or more of the peak intensity is 7.4% larger than that of the normal distribution curve (FIG. G22B (d)).
The average pitch of the recesses is 3.5 μm, and the average depth is 1.2 μm.
・ Light diffusion sheet 5
On a transparent base film (A4300, manufactured by Toyobo Co., Ltd., made of polyethylene terephthalate) with a thickness of 125 μm, uniformly on the surface by speckle pattern exposure (direction perpendicular to the light incident surface longitudinal direction (second direction)) A light diffusing sheet having a light diffusing layer made of an ultraviolet curable resin cured product in which a plurality of recesses having long openings are formed.
The diffusion angle of the entire light diffusion layer is 25 ° in the first direction and 1 ° in the second direction, and the range of the emission angle with a peak intensity of 3/4 or more in the light emission pattern curve in the first direction is a normal distribution curve. The range of the emission angle that is 6% smaller than that and the peak intensity is 1/10 or more is equal to that of the normal distribution curve (FIG. G22B (e)).
The average pitch of the recesses is 7.0 μm, and the average depth is 1.9 μm.

・ Light diffusion sheet A
Toray Saehan having a light diffusing layer on the transparent base film having a plurality of recesses (average pitch 16 μm, average depth 5 μm) having isotropic openings as shown in FIG. G24 on the surface. Diffusion sheet TDF-187

[Table G-2]

  Moreover, in addition to the determination based on the measuring instrument as described above in Production Example G, a combination suitable for the display device by visual determination (LED arrangement pitch, uneven structure on the light incident surface of the light guide plate, and lamination on the light guide plate) Examples of the combination of optical sheets) are as follows.

  The determination was performed according to the following criteria. It was judged comprehensively based on observations from all directions as to whether the display device was suitable for display.

In the standard model with a frame (horizontal distance between the light incident surface and the display area) G = 7 mm according to the above judgment criteria, suitable combinations considering the reduction of LEDs are shown in the table below for each optical sheet arrangement. Illustrate.
In the table, “light diffusion sheet” means a light diffusion sheet bonded to the light incident surface of the light guide plate substrate.

  Assuming a narrow frame with a frame G = 4 mm in accordance with the above criteria, suitable combinations that provide good quality will be exemplified below for each optical sheet arrangement.

<Production Example H>

  Production Example H will be described. In the following Production Example H, the major axis direction (the direction in which the diffusion angle is low) of the surface uneven structure of the diffusion sheet is installed perpendicular to the point light source array.

[Production Example H-1]
When producing the diffusion sheet according to Production Example H-1, the photosensitive medium is exposed and developed with the interference light diffused through the holographic diffuser described in Japanese Patent No. 3341519, thereby developing a speckle pattern. A sub-master type having a non-periodic surface uneven structure was produced. As a holographic diffuser when exposing the photosensitive medium, a diffusion plate having a diffusion angle in the direction horizontal to the diffusion sheet of 30 degrees and a diffusion angle in the vertical direction of 0.08 degrees was used. A photo-curing resin (adhesive for optics made by Norland) applied between the sub-master mold and the base material (toyobo PET base material A4300 having a thickness of 80 microns) so as to have a thickness of about 20 micrometers. After photocuring the agent NOA63), the sub-master mold was peeled to produce a diffusion sheet according to Production Example H-1 in which a surface layer having a surface uneven structure was formed on a substrate.

  The following five types of diffusion sheets were obtained by adjusting the size, shape and direction of the speckle pattern. The direction of the speckle pattern is adjusted in consideration of the vertical and horizontal directions of the diffusion sheet to be manufactured.

[Table H-1]

[Production Example H-2]
The minimum value of the diffusion angle of each diffusion sheet obtained in Production Example H-1 was measured using a beam profiler (NanoScan) manufactured by Photon Inc., and a helium neon (He-Ne) laser 1107P manufactured by JDS Uniphase. Was measured by irradiating from the surface of each diffusion sheet having a surface uneven structure, and the following results were obtained.

[Table H-2]

[Production Example H-3]
The maximum value of the diffusion angle of each diffusion sheet obtained in Production Example H-1 was measured using a variable angle photometer (GC-5000L) manufactured by Nippon Denshoku Industries Co., Ltd., and the light from the light source was applied to the surface of each diffusion sheet. When the measurement was performed by irradiating from the surface having the concavo-convex structure, the following results were obtained.

[Table H-3]

[Production Example H-4]
A line illumination system in which five point light sources 1 are horizontally arranged on the back surface of the diffusion sheet 2 with respect to the irradiation surface 3 as shown in FIG. The point light source 1 is an LED that emits parallel light having a wavelength of 488 nm, an output of 0.18 W, an intensity of Gaussian distribution, and a range of 1 / e ² of the maximum intensity of 3 mm. The distance between adjacent point light sources was 80 cm.

  Using a 1936-C power meter manufactured by Newport, the 918D-UV-OD3 detector is used to irradiate the horizontal distribution of the irradiation light 4 on the irradiation surface 3 when the distance between the diffusion sheet 2 and the irradiation surface 3 is 1 m. Measurements were made at each point on the surface. FIG. H3 shows a case where DS174-4 is used as the diffusion sheet 2, FIG. H4 shows a case where DS175-1 is used, FIG. H5 shows a case where DS175-2 is used, FIG. H6 shows a case where DS176-1 is used, FIG. Is the intensity distribution when DS176-2 is used.

  For comparison, the maximum and minimum values of the light intensity between the positions in FIGS. H3 to H7 between −800 mm and 800 mm and the ratio of the minimum value to the maximum value of the light intensity were determined as follows. Results were obtained.

[Table H-4]

It can be seen that the ratio of the minimum intensity to the maximum intensity of light is 0.7 or more and the irradiation surface is illuminated in a uniform line shape, although the intensity is approximately 4 mW / cm ² or more regardless of which diffusion sheet is used. It was. In addition, DS174-4, DS175-1, and DS175-2 had good light intensity of 7.0 mW / cm ² or more even at the minimum value.

[Production Example H-5]
Of each diffusion sheet obtained in Production Example H-1, the surface unevenness of the diffusion sheet is obtained by sandblasting from the direction of 10 degrees obliquely with respect to the direction in which the diffusion angle of the emitted light of DS176-2 shows the minimum value. A streak pattern was formed on the surface having the structure. The processed diffusion sheet is designated DS176-2S.
About DS176-2S, when the pitch of the streak pattern was measured under an optical microscope,
The average pitch was 0.2 mm.

Next, a part of DS176-2S was cut, and the height of the streak pattern was measured from the cross-sectional shape. The average height was 0.02 mm.

[Production Example H-6]
When producing a diffusion sheet according to Production Example H-6, a photosensitive medium is exposed and developed with interference light diffused through a holographic diffuser described in Japanese Patent No. 3341519, thereby developing a speckle pattern. When producing a submaster mold having a non-periodic surface irregularity structure derived from it, the diffusion angle of the emitted light of the submaster mold is minimized by partially adjusting the size and shape of the speckle pattern during exposure. A sub-master type having a streak pattern in the direction of 8 degrees obliquely with respect to the direction indicating the value was obtained.

  Next, a diffusion sheet DS177-1V was obtained by transferring the pattern from the submaster mold obtained in this Production Example in the same manner as in Production Example H-1. Regarding DS1777-1V, the density pitch of the speckle pattern density was measured under an optical microscope, and the average pitch was 1 mm.

[Production Example H-7]
When the minimum value of the diffusion angle of the diffusion sheets obtained in Production Examples H-5 and 6 was measured in the same manner as in Production Example H-2, the following results were obtained.

[Table H-5]

[Production Example H-8]
When the maximum value of the diffusion angle of the diffusion sheets obtained in Production Examples H-5 and 6 was measured in the same manner as in Production Example H-3, the following results were obtained.

[Table H-6]

[Production Example H-9]
The diffusion sheets obtained in Production Examples H-1, 5, and 6 were subjected to a scratch resistance test in which a surface having a surface concavo-convex structure was rubbed with a pencil having a hardness of HB five times. The upper part of the pencil is sandwiched between two fingers and applied with a load of about 10 g so as to form an angle of about 30 degrees with respect to the surface of the test piece. Was moved at a speed of about 5 mm / sec. The results were as follows. In addition, (circle) in a table | surface represents that the damage | wound by rubbing with a pencil could not be visually recognized but was passed, and x represents that the damage | wound was visually recognizable and was unacceptable.

[Table H-7]

  It was found that the diffusion sheet having the streak pattern formed in the oblique direction has improved scratch resistance.

[Production Example H-11]
Similar to Production Example H-1, the following three types of diffusion sheets were obtained by adjusting the size, shape and direction of the speckle pattern. As a holographic diffuser for exposing the photosensitive medium, a diffusion plate having a diffusion angle in the vertical direction with respect to the horizontal plane of the screen and a diffusion angle in the horizontal direction was 5 degrees.

[Table H-8]

[Production Example H-12]
When the minimum value of the diffusion angle of each diffusion sheet obtained in Production Example H-11 was measured in the same manner as in Production Example H-2, the following results were obtained.

[Table H-9]

[Production Example H-13]
When the maximum value of the diffusion angle of each diffusion sheet obtained in Production Example H-11 was measured in the same manner as in Production Example H-3, the following results were obtained.

[Table H-10]

[Production Example H-14]
In the same manner as in Production Example H-4, the intensity distribution of the irradiation light 4 on the irradiation surface 3 was measured in the manufactured line illumination system. FIG. H8 shows the intensity distribution when DS142-8 is used as the diffusion sheet 2, FIG. H9 shows the intensity distribution when DS154-1 is used, and FIG. H10 shows the intensity distribution when DS156-1 is used.

  For comparison, in the same manner as in Production Example H-4, the maximum and minimum values of the light intensity between the positions in FIGS. H8 to H10 between −800 mm and 800 mm and the ratio of the minimum value to the maximum value were obtained. The following results were obtained. In DS 154-1 and DS 156-1, since the light is also diffused in the vertical direction, the maximum intensity in the horizontal direction is reduced as shown in Table H-11.

[Table H-11]

When DS142-8 was used for the diffusion sheet 2, the unevenness of the light intensity on the irradiated surface 3 was large, and it was unbearable. When DS154-1 and DS156-1 were used, the intensity was much less than 5 mW / cm ² , but the irradiated surface could not be illuminated sufficiently brightly.

<Production Example I>

  Next, Production Example I will be described.

  The optical film used in Production Example I has a plurality of openings having a long shape in one direction by speckle pattern exposure on the surface of a transparent base film (A4300, manufactured by Toyobo Co., Ltd.) made of polyethylene terephthalate and having a thickness of 125 μm. Acrylic pressure-sensitive adhesive film (Panac Co., Ltd.) laminated on release paper on the surface of the light diffusion sheet that has a light diffusion layer made of a cured UV-cured resin with depressions and does not have a light diffusion layer The product was manufactured by laminating PD-S1 manufactured by a company and a pressure-sensitive adhesive film thickness: 25 μm.

In Production Example I, the following operation was performed, and bubbles were observed visually.
Work 1: First, the release paper was peeled from the optical film. Next, both ends of the optical film were held by hand, and the angle with the one end surface of 713 mm × 3 mm of the light guide plate having a main surface of 713 mm × 410 mm and a thickness of 3 mm was adjusted. Next, the left end portion of the optical film was pressed onto one end surface of the light guide plate. Further, with the hand held at the right end of the optical film, a portion about 25 cm away from the left end of the optical film was pressed onto one end surface of the light guide plate (hereinafter referred to as “temporary sticking”). Thereafter, the optical film was pressed onto one end surface of the light guide plate at intervals of about 25 cm while moving the left hand about 25 cm. Finally, it was traced once while applying pressure to the optical film layer using a bonding jig.
Operation 2: The main surface has a rectangular shape of 713 mm × 410 mm, the light guide plates having a thickness of 3 mm are stacked in 25 layers, and the unevenness difference (displacement of the end surface) between the adjacent light guide plates is randomly 500 μm to 1 mm. The optical films were temporarily pasted one by one on a surface of 713 mm × 3 mm. After all 25 sheets were temporarily attached, 5-6 adjacent sheets were simultaneously traced once while applying pressure to the optical film layer using a bonding jig.

(Measurement of hardness)
The hardness of the elastic body was measured according to JIS K 6253. A type A durometer is typically used as a measuring instrument. For a porous material having a large pore size, such as a sponge, which is difficult to measure with a type A durometer, the rubber hardness with a type E durometer or the Asker C type durometer described in SRIS 0101 is measured and shown as the sponge hardness. .

(Production Example I-1)
In Production Example I-1, as a bonding jig, a silicone rubber Silastic J-RTV manufactured by Dow Corning was molded into a shape shown in FIG. I7 (rubber hardness 55), as shown in FIG. What was wrapped in a bag and provided with slipperiness was used. The contact length of the bonding jig to the light guide plate in a state where pressure was applied was about 3 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind.

(Production Example I-2)
In Production Example I-2, as a bonding jig, Dow Corning silicone rubber Silastic J-RTV was molded into a shape shown in FIG. I7 (rubber hardness 55), and as shown in FIG. (Registered trademark) was pasted to give slipperiness. The contact length of the bonding jig to the light guide plate in a state where pressure was applied was about 3 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind.

(Production Example I-3)
In Production Example I-3, as a bonding jig, a commercially available chloroprene rubber piece (3 mm × 50 mmφ, rubber hardness 62) was wrapped in a polyethylene plastic bag and provided with slipperiness. Although the rubber hardness of the bonding jig is high, it is thin, so that the contact length of the bonding jig to the light guide plate in a state where pressure is applied is as long as about 10 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind. Compared to Production Example I-1, the rubber hardness was high and the shape followability was slightly deteriorated. Therefore, a higher pressure was required, and workability was slightly deteriorated, but there was no problem.

(Production Example I-4)
In Production Example I-4, a sabo made by Sanshin Kosan Co., Ltd. (50 mm × 50 mm × 3 mm, rubber hardness 32) was wrapped in a polyethylene plastic bag and provided with slipperiness as a bonding jig. Since the bonding jig was soft and thin, the contact length of the bonding jig with respect to the light guide plate in a state where pressure was applied was as long as about 15 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind. Since the rubber hardness is lower than that of Production Example I-1, the efficiency with which the applied stress propagates to the stress in the direction perpendicular to the end face is reduced, so a higher pressure is required and workability is slightly deteriorated. There was no problem.

(Production Example I-5)
In Production Example I-5, VALQUA Code Seal Software (35 mm × 10 mm × 3 mm, rubber hardness 55) manufactured by Nippon Valqua Industries, Ltd. was used as a bonding jig. Since the plastic deformation property of the bonding jig was strong, the contact length of the bonding jig with respect to the light guide plate in a state where pressure was applied was as short as about 2 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind. Since it is a plastic deformation body as compared with Production Example I-1, the shape followability decreases and becomes harder each time it is used, so the life of the jig is slightly shorter, but there is no problem. .

(Production Example I-6)
In Production Example I-6, as a bonding jig, a commercially available EVA foam (95 mm × 25 mm × 10 mm, rubber hardness 28) was wrapped in a polyethylene plastic bag and provided with slipperiness. The rubber hardness of the bonding jig was low, but because of the thickness, the contact length of the bonding jig with respect to the light guide plate in a state where pressure was applied was as short as about 3 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind. Since the rubber hardness is lower than that of Production Example I-1, the efficiency with which the applied stress propagates to the stress in the direction perpendicular to the end face is reduced, so a higher pressure is required and workability is slightly deteriorated. There was no problem.

(Production Example I-7)
In Production Example I-7, as a bonding jig, a polyurethane resin (Seika No. 3 mm × 40 mmφ, rubber hardness 8) manufactured by Devica Co., Ltd. was wrapped in a polyethylene plastic bag and provided with slipperiness. Since the bonding jig is soft and thin, the contact length of the bonding jig with respect to the light guide plate in a state where pressure is applied was as long as about 15 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind. Since the rubber hardness is lower than that of Production Example I-1, the efficiency with which the applied stress propagates to the stress in the direction perpendicular to the end face is reduced, so a higher pressure is required and workability is slightly deteriorated. There was no problem.

(Production Example I-8)
In Production Example I-8, as a bonding jig, a silicone rubber Silastic J-RTV manufactured by Dow Corning was molded into a shape with a guide as shown in FIG. I10 (rubber hardness 55), as shown in FIG. Nichiban cellophane tape (registered trademark) was used to provide slipperiness. The contact length of the bonding jig with respect to the light guide plate in a state where pressure was applied was about 8 mm.

  In operation 1, bubbles could be removed. In operation 2, since the guide shape interfered with the light guide plate, the bubbles could not be removed.

(Production Example I-11)
In Production Example I-11, as a bonding jig, a commercially available bamboo spatula (rubber hardness 98) was bonded to a cello tape (registered trademark) manufactured by Nichiban Co., Ltd. to give a slip property. The contact length of the bamboo spatula with the light guide plate under pressure was 0.3 mm.

  In operation 1, in the process of tracing the optical film layer, the jig was inclined and the contact area decreased, so that the bubbles could not be removed successfully. In the operation 2, since there is no shape following property, the bubbles in the light guide plate slightly recessed cannot be removed.

(Production Example I-12)
In the case of using a bonding jig such as Production Example I-8, a work for removing bubbles can be performed only for each light guide plate (because it cannot be applied to work 2), and thus a plurality of sheets were laminated. In order to remove air bubbles from the light guide plate in a state, it is necessary to individually remove the air bubbles one by one, and the workability for removing the air bubbles is complicated. Therefore, operation 2 was performed using a rubber roller having a width substantially the same as the thickness of the light guide plate as shown in FIG. Air bubbles could be efficiently removed by rubbing along the light incident surface of the light guide plate in a state where the rollers were stacked. In particular, as the material constituting the roller surface, it was most preferable to use a material made of a soft material such as rubber so that the surface slips.
(Production Example I-13)
Operation 2 was performed using a bonding jig in which three rollers (similar to the roller in FIG. I12) were arranged in parallel as shown in FIG. I13. Specifically, when the work was performed by rubbing the roller against the light incident surface of the light guide plate in the form shown in FIG. I14, the bubbles could be efficiently removed. When this bonding jig was used, bubbles were removed continuously by three rollers only by performing a tracing operation once, so that the efficiency of removing bubbles was improved.

The surface light source device of the present invention can be used for various display devices such as notebook PCs, portable information terminals, desktop PC monitors, digital cameras, and general lighting devices.
In particular, the surface light source device of the present invention is large and thin because a plurality of point light sources are used as a light source, and luminance unevenness (hot spots) in the vicinity of the light incident surface is small and uniform luminance can be obtained over the entire light exit surface. The liquid crystal display device (television receiver) can be provided at low cost and / or in a narrow frame. In addition, since uniform light emission can be obtained over a wide range, natural lighting that does not give a sense of discomfort or discomfort even when looking directly can be realized, so (indoor) ceiling lighting and its external shape are strictly regulated by law. It is also suitable for the evacuation guide lights specified in the above.

DESCRIPTION OF SYMBOLS 1 Light guide plate 11 Light exit surface 12 Light entrance surface 13 Groove 14 Thickness direction 15 of a light guide plate 16 Direction parallel to a light exit surface 16 Normal direction 41 of a light entrance surface Transparent substrate 42 Transfer roller 5a It has a layer in which the groove structure was formed. Multilayer film 5b Multilayer film 51 having a layer having a groove structure Release film 52 Adhesive layer 53 Base film 54 Layer having a groove structure 55 Adhesive layer 56 Mount film 61 Groove 71 Multilayer having a layer having a groove structure Film 72 Roll 9 Surface light source device 91 Light guide plate 92 Point light source 93 Light incident surface 94 Area corresponding to display area 10 LED
DESCRIPTION OF SYMBOLS 101 Light emission surface 102 Width of light emission surface 11 Liquid crystal display panel 112 Display area 113 Black matrix 114 Source chip 115 Gate chip 12 Television receiver 121 Display device 122 Front cabinet 1221 Speaker 123 TV tuner circuit board 124 Power supply circuit board 125 Control circuit board 126 Back cabinet 127 Stand 26 Specific dot 26a-f Vertical bisector 262 of the line segment which connects the center point of a specific dot and the center point of an adjacent dot Polygon AF surrounding a specific dot Adjacent dot G Horizontal distance P between light incident surface of light guide plate and display area Pitch arrangement of point light source B1 Light source B2 Optical sheet B11 Linear light source (cold cathode tube (CCFL))
B12 Point light source (LED)
B13 Reflective sheet B14 Optical sheet, diffusion plate B15 Diffusion sheet B16 Surface-shaped diffusion sheet B17 Prism sheet B18 Reflective polarization sheet B101 Cold cathode tube (CCFL)
B102 LED
B103 Projection area directly above the light source B104 Projection area between the light sources B301 High diffusion angle area B302 Low diffusion angle area B303 High diffusion angle area B304 Low diffusion angle area C2-9 Illuminator C2-90 Frame C2-901 Opening C2-91 Light plate E28 Light guide member E281a Light incident portion E281b Light incident portion E282 Light exit surface E283 Light guide surface E41 Base material E42 Adhesive layer E43 Light diffusion layer G2 Light guide plate G21 First surface G22 Light incident surface G23 Groove G24 Light incident surface longitudinal direction ( (First direction)
G25 Direction perpendicular to light incident surface longitudinal direction (second direction)
H1 Point light source H2 Diffusion sheet H3 Irradiation surface H4 Irradiation light H5 Diagonal streak pattern H6 A direction H7 that gives the minimum value of the diffusion angle of the emitted light H7 A streak pattern 5 with respect to the direction 6 that gives the minimum value of the diffusion angle of the emitted light Angle I1. . . Plate member I2. . . Tape-like member I3. . . Marking I4. . . Bonding jig I5. . . Release paper I6. . . Contact part I7. . . Slip property imparting layer I8. . . Shape following layer I9. . . Pinch roller I10. . . Guide roller J1 Vertical groove sheet roll J2 Adhesive vertical groove sheet roll J21 Adhesive vertical groove sheet roll (TD direction high diffusion)
J22 Vertical groove sheet roll with adhesive (MD direction high diffusion)
J221 Small roll with fluted sheet roll with adhesive (MD high diffusion)
J222 Half slit roll roll J3 Longitudinal groove sheet with adhesive (sheet-fed)
J31 Vertical groove sheet with marking J4 Half slit sheet (sheet-fed)
J41 Half slit sheet with marking (sheet-fed)
J42 Slit white stripped half slit sheet (single wafer)
J43 Marking Slit white stripped half slit sheet (single wafer)
J5 Vertical groove seal with adhesive (strip)
J6 Slit spanning heavy release separator

  The present invention relates to a so-called edge light type surface light source device, for example, a surface light source device suitable for use in a liquid crystal display device, and a television receiver using the surface light source device.

  In the liquid crystal display device, an edge light type surface light source device is often used. Such an edge light type surface light source device generally includes a light guide plate that emits light from the light source to the liquid crystal display panel side, and an LED (light emitting diode) or CCFL (cold cathode) disposed on the side of the light guide plate. Light source such as a tube) and a prism sheet (having a prism structure having a ridge line parallel to the light incident surface of the light guide plate on the surface) for directing light emitted from the light guide plate toward the liquid crystal display panel. The The light guide plate generally has a light exit surface, a facing surface facing the light exit surface, and at least one light incident surface sandwiched between the light exit surface and the facing surface, and is incident from a side portion (light entrance surface). The light to be reflected is repeatedly reflected inside the plate and guided, and the guided light is emitted from the light exit surface to the liquid crystal display panel side by a light emitting mechanism provided on the opposing surface.

  By the way, when such a light guide plate is used in combination with a plurality of point light sources, a uniform luminance can be obtained in the central region of the light exit surface (region away from each point light source to some extent), but it is close to the point light source. In the area near the light entrance surface, the partial area directly facing the portion between the point light source and the point light source is dark, but an extremely bright so-called hot spot appears in the partial area directly facing the point light source, resulting in uneven brightness. There is a disadvantage that it ends up.

  Therefore, in the surface light source device using a plurality of point light sources as the light source, there is a problem that substantially only the center portion of the light exit surface of the light guide plate can be used.

  As a light guide plate for preventing such luminance unevenness, Patent Document 1 provides a plurality of grooves that intersect with each other in an oblique direction with respect to the traveling direction of the light beam of incident light on the facing surface that faces the light exit surface. A light guide plate is disclosed.

  Patent Document 2 discloses a light guide plate having a trapezoidal concavo-convex structure in which a symmetrical triangular shape is formed on a light incident surface, and Patent Document 3 includes an opening on a light incident surface. Light guide plates each having a substantially quadrangular shape and a recess having an arcuate corner at the bottom are disclosed.

  Further, Patent Document 4 discloses a light guide plate that is knurled on the opposite surface and periodically finely cut such as a lenticular shape on the light incident surface. Patent Document 5 discloses a light guide plate on the light incident surface. A light guide plate provided with an anisotropic light diffusing adhesive layer comprising an adhesive and a needle-like filler is disclosed.

JP 2003-107247 A JP 2002-169034 A JP 2003-215346 A JP 2006-49286 A JP 2008-34234 A

  However, in the light guide plates disclosed in Patent Documents 1 to 5, improvement in luminance unevenness when used in combination with a plurality of point light sources is not sufficient, and hot spots near the light incident surface cannot be erased.

  Furthermore, the techniques disclosed in Patent Documents 2 and 3 are complicated in the structure of irregularities and depressions formed on the light incident surface, and thus are compatible with small LEDs having a light emitting surface width of 5 mm or less that have been used in recent years. It is difficult to provide a sufficient number of irregularities and depressions on the light emitting surface. Moreover, since the technique disclosed in Patent Document 4 needs to perform a rotlet cut on the opposite surface of the light guide plate, it is difficult to apply to a light guide plate used in a large-sized liquid crystal television, and costs increase. . Moreover, since the anisotropic light-diffusion adhesive layer in the technique currently disclosed by patent document 5 has the structure by which the acicular filler is disperse | distributed in an adhesive, the precision of anisotropy is low and it is immediately after light-guide plate light incidence. Light leakage is so severe that a quality sufficient for use in a display device cannot be obtained.

  The present invention has been made in view of the above points, and while using a plurality of point light sources, there is almost no occurrence of luminance unevenness (hot spots) in the vicinity of the light incident surface of the light guide plate. It is an object of the present invention to provide a surface light source device having a uniform luminance distribution over almost the entire light output surface and a television receiver using the surface light source device as a liquid crystal display device.

As a result of intensive studies on the light guide plate, the present inventors have provided a plurality of concave portions or convex portions having long anisotropic shapes in the direction perpendicular to the light exit surface on the light incident surface. It has been found that luminance unevenness derived from a point light source can be reduced.
In addition to this, in the area near the light entrance surface of the light guide plate and / or the light entrance surface thereof, the portion where the light scattering degree of the partial region directly facing the point light source faces the portion between the point light source and the point light source When light scattering processing is performed so that the light scattering degree of the region is lower, the effect of the plurality of concave portions or convex portions provided on the light incident surface and the effect of the light scattering processing are combined to produce a hot spot or other It was found that the luminance unevenness derived from the plurality of types of point light sources can be eliminated, and a uniform luminance distribution can be obtained over the entire light exit surface.

  Furthermore, a surface light source device or a display device can be obtained by subjecting a specific region or a partial region to light scattering processing for a region other than the light exit surface of the light guide plate and / or a region near the light incident surface of the light guide plate. It has also been found that not only unevenness visually recognized from the front of (light-emitting surface) but also occurrence of unevenness visually recognized from an oblique direction can be suppressed.

  If the light guide plate of the present invention is used, even when a plurality of point light sources are used as the light source, it is possible to provide a surface light source device and a display device with almost no luminance unevenness.

It is the schematic of an example of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a surface profile figure which shows an example of the some recessed part or convex part (groove structure) formed in the light-incidence surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a surface profile figure which shows an example of the some recessed part or convex part (groove structure) formed in the light-incidence surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is explanatory drawing of the specific example of the manufacturing method of an uneven structure. It is sectional drawing of the multilayer film for light-guide plate manufacture in which the uneven structure was formed. It is the schematic of the sealing sheet of the multilayer film (sealing) for light-guide plate manufacture in which the uneven structure was formed. It is explanatory drawing of the specific example of the manufacturing method of the multilayer film (tape) for light-guide plate manufacture in which the uneven structure was formed. Explanatory drawing of a diffusion angle. It is the front schematic of the surface light source device of this invention. It is the schematic of the point light source (LED) which can be utilized for the surface light source device / TV receiver of this invention. It is the front schematic diagram of the liquid crystal display panel using the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows an example of a structure of the television receiver of this invention. It is explanatory drawing of the pitch and the depth of the recessed part which the light-guide plate contained in the surface light source device / TV receiver of this invention has in a light-incidence surface. It is a microscope picture which shows an example of the recessed part formed in the light-incidence surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. Transmission of light incident from the normal direction to a multilayer film (seal) for manufacturing a light guide plate having a plurality of recesses or projections in a direction perpendicular to the major axis of the opening (bottom surface) of the recess (projection) It is an angle distribution map of light intensity. It is a microscope picture of the specific example of a moth eye structure. It is a microscope picture of the specific example of several recessed part which has a moth eye structure on the surface. It is a conceptual diagram which shows an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows the luminance distribution of manufacture example A1-4. It is a graph which shows the standard deviation of the brightness | luminance in the light emission surface of manufacture example A1-4. It is sectional drawing of the preferable example of a liquid crystal display device provided with the surface light source device of this invention. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a surface profile figure which shows an example of several recessed part or a convex part. It is a photograph of the specific example of the reel which can be used for manufacture of the film (tape) for light-guide plate manufacture which formed the several recessed part or convex part. It is explanatory drawing of a dot density. It is sectional drawing of an example of a liquid crystal display device provided with the surface light source device of this invention. It is the elements on larger scale which show the example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show the specific example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows the light-scattering process given to the opposing surface of the light-guide plate of the surface light source device of manufacture example A-5. It is a figure which shows the brightness nonuniformity (SD value) of the surface light source device of manufacture example A-5, and P / G. It is a figure which shows the light-scattering process given to the opposing surface of the light-guide plate of the surface light source device of manufacture example A-6. It is a figure which shows the light-scattering process given to the opposing surface of the light-guide plate of the surface light source device of manufacture example A-11. It is a figure which shows the relationship of the brightness nonuniformity (SD value) of manufacture example A-11, and P / G. It is a figure which shows the brightness nonuniformity (SD value) of manufacture example A-13, and the relationship of P / G. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows arrangement | positioning of the reflective sheet bonded by the side surface of the light-guide plate in manufacture example A-14-15. It is a figure which shows arrangement | positioning of the reflective sheet bonded by the side surface of the light-guide plate in manufacture example A-14-15. It is a figure which shows arrangement | positioning of the reflective sheet bonded by the side surface of the light-guide plate in manufacture example A-14-15. (A), (b) The schematic sectional drawing of the principal part of a light source unit for demonstrating the relationship between the distance of a light source and an optical sheet, the distance between light sources, and brightness | luminance unevenness is shown. (A) The projection area | region of the line light source which comprises a light source unit, and the projection area | region between line light sources are shown. (B) The projection area of the point light source which comprises a light source unit, and the projection area between point light sources are shown. (A) Explanatory drawing of a diffusion angle is shown. (B) A schematic diagram of transmitted light intensity when light enters from the normal direction of the diffusion sheet is shown. The distribution (for 1 period) of the diffusion angle with respect to the relative position in the diffusion sheet surface is shown. (A)-(f) The distribution with respect to the relative position in a surface of the diffusion angle of the diffusion sheet of specification 1st invention is shown. An example of arrangement | positioning of the high diffusion angle area | region and low diffusion angle area | region of the diffusion sheet of specification 1st invention is shown. An example of arrangement | positioning of the high diffusion angle area | region and low diffusion angle area | region of the diffusion sheet of specification 1st invention is shown. An example of arrangement | positioning of the high diffusion angle area | region and low diffusion angle area | region of the diffusion sheet of specification 1st invention is shown. (A) The schematic perspective view of an example of the light source unit of specification 1st invention is shown. (B) A schematic perspective view of another example of the light source unit of the first invention of the specification is shown. (A) The schematic perspective view of an example of the light source unit of specification 1st invention is shown. (B) A schematic perspective view of another example of the light source unit of the first invention of the specification is shown. (A) Explanatory drawing of a diffusion angle period and a light source space | interval in an example of the light source unit of specification 1st invention is shown. (B) Explanatory drawing of a diffusion angle period and light source space | interval in another example of the light source unit of 1st specification of this invention is shown. Explanatory drawing of an example of the relative positional relationship of the diffusion angle distribution of the diffusion sheet of specification 1st invention and a light source is shown. (A)-(c) The schematic perspective view of the specific structure of the light source unit of specification 1st invention is shown. (A), (b) The schematic perspective view of the specific structure of the light source unit of specification 1st invention is shown. (A)-(d) The schematic perspective view of the specific structure of the light source unit of specification 1st invention is shown. (A), (b) The schematic perspective view of the specific structure of the light source unit of specification 1st invention is shown. The arrangement pattern figure of the LED light source in manufacture example B is shown. (A) Explanatory drawing of the relative positional relationship of a diffusion angle distribution and a light source in the diffusion sheet of manufacture example B-7 is shown. (B) Explanatory drawing of the relative positional relationship of a diffusion angle distribution and a light source in the diffusion sheet of manufacture example B-8 is shown. It is the front schematic of the liquid crystal display panel using the light-guide plate contained in the surface light source device of this invention. It is a conceptual diagram which shows an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a conceptual diagram which shows an example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows the luminance distribution of manufacture example C-1 to 3 and 11. It is a graph which shows the standard deviation of the brightness | luminance in the light emission surface of manufacture examples C-1 to 3 and 11. It is a graph which shows the relationship between light scattering processing, the overlap of a flame | frame, and in-plane brightness | luminance. It is the figure which plotted the result (relationship of P / G and ρ2 / ρ1) of the reference experiment C2. It is the schematic of an example (ceiling lighting apparatus) of an illuminating device. It is a front view of an example (evacuation guide light) of an illuminating device. It is a figure which shows the luminance distribution of manufacture example C-21 and 31-33. It is a figure which shows the relationship between the distance from the light-incidence surface of the light-emitting plate of manufacture example D and a reference, and a brightness | luminance. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a graph which shows the relationship between the luminance unevenness of the manufacture example D and a reference, and the direction of a vertical groove. It is a graph which shows the brightness nonuniformity at the time of providing a groove structure in the light-incident surface with a gap. It is a graph which shows the brightness nonuniformity at the time of providing a groove structure in the light-incident surface with a gap. Luminance unevenness of Production Examples D-16 and 17 (surface light source device using a light guide plate having a vertically long recess) and Production Examples D-35 and 36 (surface light source devices using a light guide plate having a lateral groove recess) are shown. It is a graph. It is a graph which shows the luminance unevenness of manufacture example D and a reference, and the relationship of P / G. It is a figure which shows the relationship between the diffusion angle of a light-incidence surface, and luminance unevenness. It is a surface profile figure which shows an example of several recessed part or convex part (groove structure) formed in the light-incidence part of a light guide member. It is a surface profile figure which shows an example of several recessed part or convex part (groove structure) formed in the light-incidence part of a light guide member. It is a surface profile figure which shows an example of several recessed part or convex part (groove structure) formed in the light-incidence part of a light guide member. It is sectional drawing of an example of a light guide member. It is a brightness | luminance profile of the light emission surface of the light-guide plate of the surface light source device of manufacture example E-1A. It is a brightness | luminance profile of the light emission surface of the light-guide plate of the surface light source device of manufacture example E-1B. It is a graph showing the relationship between G 'and G _0'. It is the elements on larger scale which show the specific example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is the elements on larger scale which show the specific example of the light-scattering process given to the light emission surface and / or opposing surface of the light-guide plate contained in the surface light source device / TV receiver of this invention. It is a figure which shows the light-scattering process given to the opposing surface of the light-guide plate of the surface light source device of manufacture example F-11. It is a figure which shows the relationship of the brightness nonuniformity (SD value) of the surface light source device of manufacture example F-11, and P / G. It is a figure which shows the light-scattering process given to the opposing surface of the light-guide plate of the surface light source device of manufacture example F-12. It is explanatory drawing of an example of the light emission pattern curve to the 1st direction of the whole light-incidence surface of the light-guide plate of specification 2nd invention. It is an isometric view schematic diagram of an example of the light-guide plate of specification 2nd invention. In the light guide plate of the specification second invention, an example of a plurality of recesses (grooves) formed in regions (first partial region and second partial region) having anisotropic light diffusion characteristics of the light incident surface It is a top view. In the light guide plate according to the second aspect of the present invention, the plurality of recesses (grooves) formed in the regions (first partial region and second partial region) having anisotropic light diffusion characteristics on the light incident surface It is a top view of an example. (A)-(f) It is a schematic diagram which shows the example of the partial area | region formed in the light-incidence surface of the light-guide plate of specification 2nd invention. It is explanatory drawing of the determination method of angle distribution (diffusion angle) of the emitted light intensity of a partial area | region when the size of a partial area | region is small with respect to the laser diameter of the laser light source used for a measurement. It is angle distribution of the emitted light intensity to the 1st direction of the 1st partial region alone. It is a figure which shows an example of the bright line which generate | occur | produces in a light emission surface when a diffusion structure is formed in the light-incidence surface of a light-guide plate. It is a schematic diagram which shows an example of the lenticular lens shape which can be formed in the 1st surface and / or 2nd surface of the light-guide plate of specification 2nd invention. It is sectional drawing which shows the lenticular lens shape which can be formed in the 1st surface and / or 2nd surface of the light-guide plate of the manufacture example G. It is a perspective view which shows the random several groove | channel which can be formed in the 1st surface and / or 2nd surface of the light-guide plate of specification 2nd invention. (A) (b) (c) It is the light emission pattern curve to the 1st direction of the whole light-incidence surface of the light-guide plate of the manufacture example G. (D) (e) It is the light emission pattern curve to the 1st direction of the whole light-incidence surface of the light-guide plate of the manufacture example G. FIG. It is the surface shape of the light-diffusion sheet 3 used for manufacture example G. It is the surface shape of the light-diffusion sheet A used for manufacture example G. 6 is a diagram showing an evaluation direction of Production Example G. FIG. It is an overhead view of an example of the line-shaped illumination system which comprises the diffusion sheet which concerns on 1st Embodiment of specification 3rd invention. It is a figure which shows the relationship between the direction where the diffusion angle of the emitted light of the diffusion sheet which concerns on 2nd Embodiment of specification 3rd invention shows the minimum value, and a streak pattern. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-4. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-4. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-4. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-4. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-4. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-14. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-14. It is a graph which shows the light intensity distribution of the horizontal direction of the irradiation surface in manufacture example H-14. It is a perspective view which shows the one aspect | mode of the state which affixed the tape-shaped member on the end surface of the plate-shaped member which concerns on embodiment of specification 4th invention. It is a perspective view which shows the one aspect | mode of the state which affixed the tape-shaped member on the one end surface of the plate-shaped member stacked in multiple steps concerning embodiment of specification 4th invention. It is a perspective view which shows the one aspect | mode of the state which protruded to the end surface of the board which concerns on embodiment of specification 4th invention, and stuck the tape-shaped member. (A) It is a model side view which shows the method of bonding a tape-shaped member to the end surface of a plate-shaped member using the reel by which the tape-shaped member which concerns on embodiment of specification 4th invention was wound. (B) It is a model top view of the bonding part of (a). (A) It is a conceptual diagram which shows the method of bonding a tape-shaped member to the one end surface of a plate-shaped member using the bonding jig | tool which concerns on embodiment of specification 4th invention. (B) And (c) It is a schematic cross section which shows the deformation | transformation of the contact part of the bonding jig | tool at the time of bonding. (A) (b) (c) Description It is a schematic cross section which shows an example of the contact part of the bonding jig | tool which concerns on embodiment of 4th invention. (A) It is a perspective view of the bonding jig which concerns on manufacture example I-1 and 2. FIG. (B) It is sectional drawing of the bonding jig which concerns on Example 1 and 2. FIG. (A) It is a perspective view of the bonding jig | tool wrapped in the plastic bag which concerns on manufacture example I-1. (B) It is sectional drawing of the bonding jig | tool wrapped in the plastic bag which concerns on manufacture example I-1. (A) It is a perspective view of the bonding jig | tool provided with the slipperiness concerning the manufacture example I-2. (B) It is sectional drawing of the bonding jig | tool provided with the slipperiness concerning the manufacture example I-2. (A) It is a perspective view of the bonding jig which concerns on manufacture example I-8. (B) It is sectional drawing of the bonding jig which concerns on manufacture example I-8. (A) It is a perspective view of the bonding jig | tool provided with the slipperiness which concerns on manufacture example I-8. (B) It is sectional drawing of the bonding jig | tool provided with the slipperiness which concerns on manufacture example I-8. It is a schematic diagram which shows an example of the bonding jig | tool which concerns on embodiment of specification 4th invention. It is a photograph of an example of the bonding jig | tool which concerns on embodiment of specification 4th invention. It is explanatory drawing (photograph) of the bubble removal process in manufacture example I-13. It is explanatory drawing of the manufacturing process bonding method (process A1) of a longitudinal groove roll with an adhesive. It is explanatory drawing of the manufacturing process coating method (process A2) of a vertical groove roll with an adhesive material. It is explanatory drawing of the flow (in the case of TD direction high diffusion) of the manufacturing process B of a half slit sheet. It is explanatory drawing of the flow (in the case of MD direction high diffusion) of the manufacturing process C of a half slit sheet. It is explanatory drawing of process C2 (marking simultaneously with a sheeting (sheet | leaf) from a roll). It is explanatory drawing of process C3 (B3 is also substantially the same) details (half slit process to a sheet | seat sheet). It is explanatory drawing of process C4 (The half slit strip of both ends for dimensional accuracy adjustment is removed (slit white peeling)). It is explanatory drawing of the flow (rotary die method) of the manufacturing process D1 of a half slit small volume roll. Cutting process diagram D2 for small slit rolls (sheet cutting for rolls) It is explanatory drawing of marking process D3 (marking with respect to a sheet | seat sheet) of a half slit longitudinal groove sheet. It is explanatory drawing of the curvature direction of a suitable sheet | seat. It is explanatory drawing of the slit depth which reaches a suitable heavy peeling separator. It is explanatory drawing of the slit and strip deviation 1 which reach a heavy peeling separator. It is explanatory drawing of the slit and strip gap 2 which reach a heavy peeling separator. It is explanatory drawing of a Lambert LED. It is the schematic of high diffusion LED. It is a graph showing the light emission characteristic of the light which injected into the light-guide plate from LED. It is the schematic diagram which showed the spreading | diffusion inside the light-guide plate of the light which injected diagonally with respect to the light-incidence surface which does not have an uneven structure on the surface. It is the schematic diagram which showed the spread within the light-guide plate of the light which injected diagonally with respect to the light-incidence surface which has an uneven structure on the surface. 1 is a schematic diagram illustrating an embodiment of the present invention using a high diffusion LED. FIG.

Specific embodiments of the light guide plate that can be used in the present invention are as follows.
[1]
A light exit surface, a facing surface facing the light exit surface, and at least one light incident surface sandwiched between the light exit surface and the facing surface, wherein the at least one light incident surface is an opening or A light guide plate having a plurality of concave portions or convex portions having an anisotropic shape whose bottom surface is long in a direction perpendicular to the light exit surface.
[2]
A substrate, an adhesive layer laminated on at least one end surface of the substrate, and a plurality of recesses laminated on the adhesive layer and having an anisotropic shape with an opening or a bottom surface extending in one direction on the surface, or The light guide plate according to [1], including a layer having a convex portion.
[3]
The light guide plate according to [1] or [2], wherein the adhesive layer is made of a material having a storage elastic modulus G ′ at 100 ° C. of 10,000 to 45,000 Pa.
[4]
The layer having a plurality of recesses or projections having an anisotropic shape with an opening or bottom surface extending in one direction on the surface has a base film layer and an anisotropic shape with an opening or bottom surface extending in one direction on the surface. It consists of a resin layer having a plurality of recesses or protrusions,
A resin layer having a plurality of recesses or protrusions having an anisotropic shape with an opening or bottom surface extending in one direction on the surface,
Photopolymerizable resin containing (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group: 70 to 99.9% by mass, and (B) photopolymerization initiator: 0.1 to 30% by mass Including a cured product of the composition,
Any of [1] to [3], wherein (A) the addition polymerizable monomer having at least one terminal ethylenically unsaturated group includes a compound having a structure represented by the following general formula (I) having a biphenyl group: The light guide plate according to claim 1.
Formula (I)

(In the formula, R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.)
[5]
The light guide plate according to [4], wherein the compound having a structure represented by the general formula (I) has a structure represented by the following general formula (II).
Formula (II)

(In general formula (II), R represents a hydrogen atom or a methyl group, A independently represents an alkylene group having 1 to 4 carbon atoms, and n represents an integer of 1 to 3).
[6]
The adhesive layer and the surface having a plurality of recesses or protrusions having an anisotropic shape with an opening or bottom surface extending in one direction on the surface have a slipperiness-imparting layer made of a slip-providing material on the surface, Bonded to one end surface of the base material using a bonding jig having a shape following layer made of a material having a shape following property and having a rubber hardness of 10 to 70 located inside the slipperiness-imparting layer The light guide plate according to any one of [2] to [5].
[7]
The adhesive layer and a layer having a plurality of recesses or protrusions having an anisotropic shape having a long opening or bottom surface in one direction on the surface were bonded to one end surface of the substrate by the following bonding method. The light guide plate according to any one of [2] to [6]:
A laminated body in which an adhesive layer and a layer having a plurality of recesses or protrusions having an anisotropic shape with an opening or a bottom surface extending in one direction on the surface are laminated, and the thickness of the one end face of the substrate Preparing a laminate having substantially the same or narrower width; and
A laminating step in which the adhesive layer of the laminate is opposed to the one end surface, and the laminate is laminated on the one end surface;
A bonding jig comprising a member having a shape following property, while applying pressure on a layer having a plurality of concave portions or convex portions having an anisotropic shape with an opening or a bottom surface extending in one direction on the surface. A close contact process that is traced at least once in the longitudinal direction of the end face;
A laminating method.
[8]
Diffusion in a direction perpendicular to the one direction when light rays are incident on the surface having a plurality of recesses or protrusions having an anisotropic shape whose opening or bottom is long in one direction from the normal direction. The light guide plate according to any one of [1] to [7], wherein the angle is 30 ° to 120 °.
[9]
The entire light incident surface has anisotropic light diffusion characteristics in which the diffusion angle of incident light from the normal direction in the longitudinal direction of the incident surface is greater than the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface. And
The light emission pattern curve of the entire light incident surface with the horizontal axis representing the emission angle of the light emitted from the normal direction of the light incident surface in the longitudinal direction of the light incident surface and the vertical axis representing the intensity appears in the light emission pattern curve. When compared with a normal distribution curve passing through a total of three points: one peak point where the intensity of the emitted light is the peak intensity and two intermediate points where the intensity of the emitted light is half of the peak intensity, the following conditions 1. And / or condition 2. The light guide plate according to any one of [1] to [8], wherein:
Condition 1. The range of the emission angle where the intensity of the emitted light is 3/4 or more of the peak intensity is narrower than the normal distribution curve.
Condition 2. The range of the emission angle where the intensity of the emitted light is 1/10 or more of the peak intensity is wider than the normal distribution curve.

[10]
The light guide plate according to any one of [1] to [9], wherein the light exit surface and / or the opposing surface has a groove structure substantially parallel to a normal direction of the light incident surface.
[11]
The groove structure is a lenticular lens shape or a plurality of random grooves [9]
The light guide plate described in 1.

  An embodiment of the light guide plate of the present invention will be specifically described below with reference to FIG. 1 showing a schematic diagram of an example thereof.

The light guide plate 1 of the present invention has a light exit surface 11, a facing surface facing the light exiting surface, and at least one light incident surface 12 sandwiched between the light exiting surface and the facing surface.
In the light guide plate of the present invention, light from a light source arranged in the vicinity is incident on the light guide plate 12 from the light incident surface 12, is repeatedly reflected inside the plate and guided, and the guided light faces the light output surface. The light exits from the light exit surface 11 toward the light exit surface 11 by an opposing surface (not shown).

  In order to reduce luminance unevenness, the light guide plate has a plurality of concave portions or convex portions 13 having an anisotropic shape in which the opening portion or the bottom surface is long in the direction perpendicular to the light exit surface, on the light incident surface 12. In the light guide plate 1 of FIG. 1, the plurality of recesses or projections having an anisotropic shape whose opening or bottom is long in the direction perpendicular to the light exit surface are grooves substantially perpendicular to the light exit surface 11.

  When the angle between the major axis of the opening (bottom) of the recess (convex) and the direction perpendicular to the light exit surface is 40 degrees or less (even if it is not 0 degree), the opening of the recess (convex) (Bottom surface) shall be “having a long anisotropic shape in the direction perpendicular to the light exit surface”, but the length of the opening (bottom surface) of the recess (convex portion) and the direction perpendicular to the light exit surface. The angle is preferably 10 degrees or less, more preferably 8 degrees or less, more preferably 6 degrees or less, more preferably 4 degrees or less, and most preferably 0 degrees. Here, the major axis of the opening (bottom surface) refers to the long side of the circumscribed rectangle that minimizes the area circumscribing the opening (bottom surface).

  Concave part (convex part) in which the shape of the opening (bottom surface) is other than the anisotropic shape long in the direction perpendicular to the light exiting surface (for example, the opening (bottom surface) is isotropic such as a circle) There may be a shape or an opening (bottom surface) having an anisotropic shape, but the major axis is not parallel to the direction perpendicular to the light exit surface. However, the sum of the areas of the openings (bottom surfaces) of the recesses (projections) having an anisotropic shape with the opening (bottom surface) long in the direction perpendicular to the light exit surface is the opening of the other recesses (projections). It is preferable to exceed the total area of (bottom surface).

  The ratio of the major axis to the minor axis (major axis / minor axis) of the anisotropic shape is not limited, but is preferably 2 or more, more preferably 10 or more. Here, the minor axis and the major axis refer to the short side and the long side of the circumscribed rectangle having the smallest circumscribed area, respectively.

  The anisotropic shape is not limited, and specific examples thereof include a straight line (groove) as shown in FIG. 1 and a substantially elliptical shape as shown in FIG.

  The shape of the opening surface (bottom surface) of the concave portion (convex portion) can be determined by observing an arbitrary portion of the light incident surface with a microscope (such as a scanning electron microscope or a laser confocal microscope).

  The pitch in the direction parallel to the light exit surface of the recesses (projections) is not limited, but the average pitch is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The average pitch is preferably 580 nm (the central wavelength of visible light) or more, and more preferably 780 nm (the entire visible light region) or more.

  Since the light emitting surface size (width) of a commonly used point light source is about several millimeters, if the average pitch is set to such a value, a sufficient number of concave or convex portions are allocated to the light emitting surface of the point light source. This eliminates the need to strictly determine the alignment accuracy between the light source and the light guide plate. Further, when the average pitch is set to such a value, the claw or the like is hardly caught on the concave portion or the convex portion during handling, and the handling property is improved. Furthermore, since the light diffused by the light guide plate included in the surface light source device of the present invention is visible light (an electromagnetic wave of 380 nm to 780 nm), the average pitch is the above in order to sufficiently exhibit the diffusion effect by the concave portion or the convex portion. It is preferable that the value is as follows.

Here, the pitch in the direction parallel to the light exit surface of the concave portion (convex portion) means the adjacent valley bottom (in the case of the concave portion) or peak (in the case of the convex portion) in an arbitrary cross section parallel to the light exit surface of the light incident surface. The horizontal distance between them (the distance in the direction parallel to the light incident surface) (see FIG. 13). If the valley bottom (mountain peak) is flat, the pitch is determined with the center as the valley bottom (peak peak).
Further, the average pitch in the direction parallel to the light exit surface of the concave portion or the convex portion is the average pitch of the concave portion (convex portion) present at 100 μm arbitrarily extracted from an arbitrary vertical cross section parallel to the light exit surface of the light incident surface. Value.

  The (average) pitch in the direction parallel to the light exit surface of the concave portion (convex portion) is observed and measured with a microscope (such as a scanning electron microscope or a laser confocal microscope) in an arbitrary cross section parallel to the light exit surface. Can be determined by

There is no limitation on the size (depth / height) of each recess (projection).
For example, the minor axis of the opening (bottom surface) may be 580 nm to 100 μm, 780 nm to 60 μm, or 1 to 20 μm. Further, the major axis of the opening (bottom surface) may be, for example, 5 μm or more and 2 cm or less.
The depth (height) may be, for example, 500 nm to 50 μm, 700 nm to 30 μm, or 5 to 10 μm. The average depth (height) of the concave portion or convex portion is also preferably 500 nm to 50 μm, more preferably 700 nm to 30 μm, and further preferably 5 to 10 μm.

Here, the depth (height) of the concave portion (convex portion) is defined between the peak of the higher mountain and the valley bottom of the concave portion among the peaks on both sides constituting each concave portion in an arbitrary cross section of the light incident surface. The vertical distance (the distance in the direction perpendicular to the light incident surface) (the difference in elevation between the peak and the valley bottom) between the valley bottom of the lower valley and the peak of the peak among the valleys on both sides constituting the protrusion. (See FIG. 13) The average depth (height) of the concave portion or convex portion is the depth (height) of the concave portion (convex portion) existing at 100 μm arbitrarily extracted from an arbitrary vertical cross section of the light incident surface. The average value of
The size of the concave portion (convex portion) can be determined by observing and measuring an arbitrary portion of the light incident surface with a microscope (such as a scanning electron microscope or a laser confocal microscope).

  However, when the shape of the recess (projection) is a groove (ridge), the length is preferably larger than the length of the light emitting surface of the point light source in the thickness direction of the light guide plate. That is, it is preferable that the length of the groove (畝) is not less than the size of the light emitting surface of the point light source and not more than the thickness of the light guide plate. In FIG. 1, the groove has a length that traverses the light incident surface in the thickness direction of the light guide plate (from the light exit surface to the opposite surface), but the length of the groove (畝) is not necessarily light incident. It does not have to cross the plane.

The plurality of recesses (projections) is not a periodic structure as in the prior art, but the shape, size (depth, height) of the plurality of recesses (projections) and the pitch in the direction 15 parallel to the light exit surface It is preferable that at least one of them is randomly (irregularly) different because luminance unevenness reduction effect (especially hot spot reduction) is improved.
Here, being different at random means that a value (3 sigma) obtained by multiplying a standard deviation calculated from a plurality of measured values exceeds 10% of the average value.

  There is no particular limitation on the region where the concave portion or the convex portion on the light incident surface is arranged, and it can be appropriately determined according to the light emission distribution and arrangement of the light source used in combination with the light guide plate. That is, the light guide plate included in the surface light source device of the present invention may have a portion (region) having no concave portion or convex portion on the light incident surface. But it is preferable that the recessed part or convex part is arrange | positioned at least in the area | region facing the light emission surface of a light source.

  Moreover, although there is no limitation in the density of a recessed part or a convex part, about the area | region which opposes the light emission surface of a light source among the light-incidence surfaces of a light-guide plate, the sum total of the area of the opening part (bottom surface) of a recessed part (convex part). Occupy 25% or more (more preferably 50% or more, still more preferably 70% or more) of the region.

Specific examples of the plurality of recesses or protrusions shown in FIGS. 2 and 3 and FIGS. 23 to 32.
In the examples of FIGS. 2 and 3, the concave portion or the convex portion is a groove. The plurality of grooves (groove structure) in FIG. 2 is anisotropic with a diffusion angle in a direction perpendicular to the groove (defined by FWHM described later) of 60 degrees and a diffusion angle in a direction parallel to the grooves of 1 degree. Has diffusion properties. The groove structure of FIG. 3 has anisotropic diffusion characteristics in which the diffusion angle in the direction perpendicular to the groove is 30 degrees and the diffusion angle in the direction parallel to the groove is 1 degree.
Table 1 shows the diffusion angle, average pitch (average pitch in the direction perpendicular to the major axis direction (groove) of the recess), and average depth in FIGS . In Table 1, “horizontal” means a direction perpendicular to the direction of the major axis of the opening of the recess (perpendicular to the groove), and “vertical” means a direction parallel to the major axis of the opening of the recess ( The direction (parallel to the groove).

Table 1

Another specific example of a plurality of concave portions or convex portions is shown in FIGS . In all the examples of FIG. 3, the concave portion or the convex portion is a groove. The plurality of grooves (groove structures) in FIG. 98 have anisotropic diffusion characteristics in which a diffusion angle in a direction perpendicular to the grooves (described later) is 83 degrees and a diffusion angle in a direction parallel to the grooves is 3 degrees. . The groove structure (b) has anisotropic diffusion characteristics in which the diffusion angle in the direction perpendicular to the groove is 75 degrees and the diffusion angle in the direction parallel to the grooves is 0.2 degrees. The groove structure (c) has anisotropic diffusion characteristics in which the diffusion angle in the direction perpendicular to the groove is 65 degrees and the diffusion angle in the direction parallel to the grooves is 7 degrees.

A moth-eye structure may be provided on the surface of the plurality of concave portions or convex portions for the purpose of reducing reflection on the light incident surface and efficiently using incident light. Here, the “moth eye structure” means that convex portions having substantially the same shape with a height of 1 μm or less are substantially periodic (for example, a square lattice shape, a rectangular lattice shape, a square quadrangular lattice shape, a triangular lattice shape (honeycomb)). Alternatively, it means a fine uneven structure provided in a hexagonal lattice pattern with a pitch of about 50 to 500 nm. Here, the “fine concavo-convex structure” refers to concavo-convex whose average height is 1/10 or less of the average depth (height) of the plurality of concave portions (convex portions). The height may be 50 to 500 nm or 100 to 300 nm.
The concavo-convex structure is preferably composed of a plurality of convex portions. There is no limitation in the shape of each convex part, For example, a tent shape, a cone shape, a bell shape, a polygonal pyramid shape, a hemispherical shape etc. are mentioned, It is preferable that the average height is 1 micrometer or less.
Specific examples of the moth-eye structure and the recess (groove) having the moth-eye structure on the surface are shown in FIGS. 16 and 17, respectively.

  A plurality of concave portions or convex portions (hereinafter sometimes referred to as “concave structure”) having an anisotropic shape whose opening or bottom is long in the direction perpendicular to the light exit surface on the light incident surface of the light guide plate of the present invention. There is no limitation on the method of forming the film. For example, (1) a method of injection molding a light guide plate using a mold having a concavo-convex pattern corresponding to the concavo-convex structure, (2) a light guide plate (base material) using a transfer mold having a concavo-convex pattern corresponding to the concavo-convex structure And (3) a method of bonding a layer having a concavo-convex structure on the surface to a light guide plate (base material) using a translucent adhesive (adhesive) or the like. Etc. can be used.

  It should be noted that the effect of the present invention is not exhibited unless the layer having the concavo-convex structure is attached to the light incident surface with a transparent optical adhesive or the like and integrated with the light guide plate. In other words, simply disposing the layer having the concavo-convex structure between the light incident surface of the light guide plate and the light source diffuses the incident light inside the light guide plate to a wide angle (and more, hot spots and other It is impossible to eliminate luminance unevenness derived from the point light source.

  As a method of (1), for example, a stamper having a concavo-convex pattern corresponding to the concavo-convex structure is disposed at a position corresponding to the light incident surface of a mold for forming the light guide plate, and the light guide plate having the concavo-convex structure is injection molded from the beginning. can do. This method is suitable for manufacturing a light guide plate for a surface light source device used for a relatively small (about 32 type or less) image display device.

  As a method of (2), for example, after forming a light guide plate (base material) (raw sheet for light guide plate production) that does not have a concavo-convex structure by extrusion molding or cast molding, a light incident surface (light incident surface) The concavo-convex structure can be transferred using a transfer mold having a concavo-convex pattern corresponding to the concavo-convex structure on the surface.

  FIG. 4 shows a specific example of this method. In the method of FIG. 4, a plurality of transparent substrates 41 cut to a predetermined size are stacked, and light incident on the transparent substrate while heating a transfer roller 42 having a concavo-convex pattern corresponding to a concavo-convex structure (here, a groove structure) on the surface. The uneven structure is transferred by pressing against the surface. According to this method, since transfer can be performed collectively on a plurality of light guide plates, mass production is possible and quality is improved.

  The specific procedure of the method (3) is not limited, and an adhesive layer and a layer having a concavo-convex structure on the surface may be sequentially bonded to the substrate (the layer having a concavo-convex structure on the surface is a transparent base film). When the layer and the resin layer having a concavo-convex structure on the surface, the adhesive layer may be bonded with a transparent base film layer and a resin layer, or the adhesive layer, the transparent base film layer, The resin layers may be bonded in this order). Alternatively, a laminate in which an adhesive layer and a layer having a concavo-convex structure are bonded in advance is prepared, and this may be bonded to a substrate.

In the case of sequentially bonding an adhesive layer and a layer having a concavo-convex structure on the surface to the substrate, a method of bonding an adhesive layer to the substrate, and a method of bonding a layer having a concavo-convex structure on the surface thereon There is no limitation.
Since the adhesive layer itself is sticky, each layer may be simply laminated, and after lamination, the layers are brought into close contact with each other by ventilating the air using a tool such as a spatula or a highly rigid roller. May be. As such a jig, a bonding jig according to the fourth invention of the present specification described later (for example, a shape having a slipperiness imparting layer made of a slippery imparting material on the surface and positioned inside the slipperiness imparting layer) It is preferable to use a bonding jig having a shape following layer made of a material having a following property and a rubber hardness of 10 to 70).

  According to the study by the present inventors, it was found that when the ratio of the portion where the air layer is interposed between the layers in the laminated region is 10% by area or less, delamination hardly occurs under high temperature and high humidity. . Therefore, it is very effective to use a jig to evacuate the air between the layers until the ratio of the portion where the air layer is interposed is 10 area% or less.

  Using an adhesive layer with a release sheet laminated on one side, sticking the adhesive layer to the substrate, venting as necessary, then peeling off the release sheet and forming a concavo-convex structure on the surface You may make it stick the layer which has.

  Also, prior to the bonding of the adhesive layer on the substrate, or the bonding of the layer having an uneven structure on the surface thereof, the uneven structure on the substrate and / or the adhesive layer, the adhesive layer and / or the surface. After the surface molecular bond is cut by applying a surface treatment such as excimer UV treatment or corona treatment to the layer having, the bonding strength can be improved by immediately bringing them into close contact.

In the case of preparing a laminate in which an adhesive layer and a layer having a concavo-convex structure on the surface are prepared in advance and pasting the laminate on a substrate, the following method can be employed. This method will be described in detail in the description related to the fourth invention of this specification described later.
A laminate in which an adhesive layer and a layer having a concavo-convex structure on the surface are laminated, and a step of preparing a laminate having a width substantially equal to or narrower than the thickness of one end surface of the substrate;
A laminating step in which the adhesive layer of the laminate is opposed to the one end surface, and the laminate is laminated on the one end surface;
An adhesion step comprising a member having a shape following property, while applying pressure on the surface having a concavo-convex structure on the surface, and an adhesion step of tracing one or more times in the longitudinal direction of the one end surface;
A laminating method.

As a specific example of a method of preparing a laminate in which an adhesive layer and a layer having a concavo-convex structure on the surface are previously prepared and affixing the laminate to a substrate, a. A sealing mold, and b. There are two types of tape-type methods.
a. Seal type For example, an ultraviolet curable resin layer is applied on a transparent base film made of polyethylene terephthalate, polycarbonate, polystyrene, etc., and an uneven structure is formed on the ultraviolet curable resin layer by a method using a speckle pattern described later. Then, a layer having a concavo-convex structure is formed on the surface. Although there is no limitation in the thickness of a base film, it can be 20-250 micrometers, for example, Preferably it is 50-125 micrometers.

  Next, an adhesive (adhesive) is applied to the surface of the base film opposite to the surface on which the concavo-convex structure is formed, and a release film made of polyethylene terephthalate or the like is bonded thereto, or a release film is attached. A multilayer film in which the adhesive side is covered with a release film is produced by bonding the adhesive layer of the adhesive film. A specific example of the layer structure of such a multilayer film is shown in FIG. 5a and 5b in FIG. 5 are both multilayer films provided with a release film on one side. In the multilayer film 5a, a release film 51, an adhesive layer 52, a base film 53, and a resin layer 54 having a concavo-convex structure (here, a groove structure) are laminated on the surface in order from the bottom. Further, in the multilayer film 5b, an adhesive layer 55 and a mount film layer 56 are further provided on the resin layer 54 on which the concavo-convex structure is formed, and a release film 51, an adhesive layer 52, a base film 53, A resin layer 54 having an uneven structure, an adhesive layer 55, and a mount film 56 are laminated. The release film 51 and the mount film 56 serve as a seal mount or a protective film during the manufacture of the light guide plate, and the thickness thereof is not limited. For example (depending on the material), 20 to 100 μm. It can be. However, in order to perform the half-cut processing more easily, the mount film is preferably 50 μm or more, and more preferably 75 μm or more. Moreover, the thickness of the contact bonding layer 52 can be 10-100 micrometers, for example. When considering the balance between performance and cost, it is preferably about 15 to 50 μm, and more preferably about 20 to 25 μm.

  Next, this multilayer film is cut in accordance with the length (width) of the light incident surface of the light guide plate. Next, in the case of the multilayer film 5a, only the release film 51 is left, and in the case of the multilayer film 5b, the mount film 56. The adhesive layer 55 is left, and the remaining layers are cut into half the same width as the thickness of the light incident surface (half-cut), thereby forming a film with an uneven structure having the same size as the light incident surface of the light guide plate ( A seal sheet is produced in which a plurality of uneven structure seals) are formed on the release film 51 (in the case of the multilayer film 5a) or the mount film 56 (in the case of the multilayer film 5b). In addition, as described above, in the case of the multilayer film 5a, since the blade of the cutting means enters from the side of the layer on which the concavo-convex structure is formed during the half-cut process, there is an advantage that there is less risk of the concavo-convex structure being broken, On the other hand, in the case of the multilayer film 5b, the blade of the cutting means enters from the side of the adhesive layer 52 during the half-cut process, so that the adhesive layer can be reliably cut and the adhesives (adhesives) stick together again. There is an advantage that the problem of “threading” is less likely to occur. Examples of the half-cutting method include, but are not limited to, a method of putting a Thomson blade in a cutting direction, a method of rolling a roll blade in a cutting direction, and a method of burning to a desired depth using a laser. In addition, there exists an advantage that cutting waste does not generate | occur | produce when a laser is used. A schematic front view of the seal sheet thus produced is shown in FIG. In FIG. 6, each vertical line indicates a groove 61.

  Then, in the manufacturing process of the light guide plate and the assembly process of the surface light source device having the light guide plate, in the case of the multilayer film 5a, the films having the uneven structure (uneven structure seal) are peeled off from the release film 51 one by one and bonded. It is bonded to the light incident surface of the light guide plate (base material) via the layer 52. In the case of the multilayer film 5 b, the film having the concavo-convex structure (the concavo-convex structure seal) is peeled off from the adhesive layer 55 one by one, and then the peelable film 51 is peeled off and bonded to the light incident surface through the adhesive layer 52. Finally, if necessary, the air between the film and the light incident surface may be brought into close contact by removing with a roller or the like.

  Prior to bonding, surface adhesion such as excimer UV treatment or corona treatment is applied to the adhesive layer 52 and / or the light incident surface to cut the surface molecular bonds, and immediately thereafter, the adhesive layer 52 and the light incident surface are formed. Bonding strength can also be improved by the close contact. Furthermore, by using such a surface treatment, it is possible to bond the base film of the film having a concavo-convex structure and the light guide plate without using an adhesive, thereby reducing the cost and improving the reliability. Can do.

  According to this seal-type method, the bonding operation to the light incident surface is facilitated, and the number of used (bonded) seals can be easily managed, so that the light guide plate can be easily manufactured. Furthermore, transportation of the light guide plate manufacturing material is facilitated.

  When manufacturing the seal sheet, the multilayer film (5a, 5b) is cut shorter than the length (width) of the light incident surface of the light guide plate, and two or more multilayer films (seal) are assembled when assembling the surface light source device. ) May be bonded to the light incident surface. At this time, the multilayer film (seal) covers 2 mm or more outside (up and down, left and right) from the area facing the light emitting surface of the light source on the light incident surface (the gap or seam between the films is in the area facing the light emitting surface). It is preferable to position and bond together.

b. Tape type b. A tape-type method will be described with reference to FIG.
a. In the same manner as in the case of the seal type, a multilayer film 71 having a layer in which an uneven structure is formed is manufactured. Next, this is cut into the same width as the thickness of the light incident surface to form a plurality of tapes, each wound on a reel (not shown) and processed into a roll 72. A specific example of the reel is shown in FIG . At this time, as shown in FIG. 33 , it is preferable to wind up with a reel having a structure sandwiched between two disks so that the wound tape does not cause axial misalignment. The diameter of the wound tape is preferably smaller than the outer diameter of the disk.

  Then, in the manufacturing process of the light guide plate and the assembly process of the surface light source device and the illuminating device having the light guide plate, a tape (tape film) having a layer having a concavo-convex structure is fed out from the roll 72 to enter the light guide plate After cutting to the length of the light surface, it is bonded to the light incident surface, or after being bonded to the light incident surface, it is cut to the length of the light incident surface. For bonding, a. The same method as described in the seal-type method can be adopted.

  According to this method, the length for cutting the tape may be determined when the tape is bonded to the light guide plate. Therefore, one type of roll (a roll of a tape-like film having a layer on which a concavo-convex structure is formed) can be of various sizes. Can be used for manufacturing a light guide plate having a large thickness, and the versatility of the roll is high. Further, it is easy to automate and speed up the process of bonding the multilayer film 71 to the light guide plate.

  The concavo-convex pattern or concavo-convex structure corresponding to the concavo-convex structure is applied to the mold (stamper), transfer mold (transfer roller) used in the methods (1) and (2) or the film used in the method (3). There is no limitation on the forming method. For example, it may be formed by machining such as cutting or sandblasting, or may be formed by laser speckle pattern exposure. The method using speckle pattern exposure is suitable for forming a fine three-dimensional structure of about 10 μm or less, which is difficult by machining, and it is easy to obtain an appropriate irregularity.

  Specifically, when speckle pattern exposure is used, a random uneven structure can be formed as follows.

  For example, a random speckle pattern or a striped speckle pattern is generated by interference exposure using laser light, and this is irradiated to a photosensitive material such as a photoresist. Next, when the exposed photosensitive material is developed by a known method, a random uneven structure corresponding to the speckle pattern is formed on the photosensitive material.

  Note that the random speckle pattern or striped speckle pattern can be generated by, for example, diffusing laser light with a diffusion layer having strong anisotropy. Normally, when the laser beam is diffused by the diffusion layer and irradiated to the exposed surface, speckles are generated as circular unevenness. However, if the diffusion layer has a strong anisotropy, the speckles have a speckled or striped pattern. be able to. Furthermore, a desired random spot / striped pattern can be obtained by appropriately changing the wavelength of the laser light, the conditions for diffusing the laser light, and the like. Specifically, it can be generated by the method disclosed in paragraphs 0047 to 0057 of JP-T-2004-508585.

  The metal mold or transfer mold having a concavo-convex pattern corresponding to the concavo-convex structure is a sub-master mold formed by the above-described concavo-convex structure, and the metal is deposited on the sub-master mold by a method such as electroforming. It can be produced by transferring a concavo-convex pattern corresponding to the concavo-convex structure.

  In addition, a method for producing a fine concavo-convex pattern using a speckle pattern by interference exposure is well known. Yes.

When the above method (3) is adopted as a method for forming a plurality of concave portions or convex portions on the light incident surface of the light guide plate, the structure of the light guide plate is laminated on at least a part of the base material. And a layer having a plurality of recesses or protrusions on the surface laminated thereon (a layer having a concavo-convex structure on the surface).
Here, the region where the adhesive layer and the layer having the concavo-convex structure are provided on the surface is a light incident surface.
If the adhesive layer and the layer having a concavo-convex structure on the surface protrude outside the base material, when assembling a surface light source device or the like using the light guide plate of the present invention, it will come into contact with and interfere with other members. Since there is a risk that the layer having the concavo-convex structure may be peeled off or the other members may be damaged, it is preferable that these are within the plane.

  In the place where the adhesive layer of the base material and the layer having the concavo-convex structure on the surface are laminated, the microscopic air to escape the bubbles generated between the base material and the adhesive layer when the light guide plate is used under high temperature and high humidity etc. One or a plurality of grooves may be formed. There is no limitation on the width, cross-sectional shape, depth, and the like of such a groove, but the width is preferably 0.5 mm or less, more preferably 0.3 to 0.01 mm. Moreover, the depth can be 0.5-0.01 mm, for example. Although the length of the groove is not limited, it is preferable that the groove is crossed or longitudinally crossed over the region where the adhesive layer is laminated.

The material of the base material is not particularly limited as long as it is translucent. For example, it is generally used as a material for optical parts such as polymethyl methacrylate, polycarbonate, polystyrene, and methyl methacrylate-styrene copolymer. A high molecular weight material (for example, a total light transmittance of 90% or more and a haze of 1.0 or less) can be used.
In addition, base materials include organic and inorganic dyes and pigments, matting agents, heat stabilizers, flame retardants, antistatic agents, antifoaming agents, color stabilizers, antioxidants, UV absorbers, as necessary. Additives such as impurity scavengers, thickeners, surface conditioners, and mold release agents may be contained within a range not impairing the object of the present invention.

An example of a cross section of such a light guide plate is shown in FIG . In FIG. 101 , E41 is a substrate, E42 is an adhesive layer, and E43 is a layer having an uneven structure on the surface.
The adhesive layer plays a role of fixing a layer having a concavo-convex structure on the surface to the base material. The material constituting the adhesive layer preferably has a storage elastic modulus G ′ at 100 ° C. of 40,000 to 180,000 Pa. When the light guide plate is incorporated into a surface light source device or a television receiver, it is used in a high temperature environment where the temperature is locally raised to about 100 ° C. or a humid environment where the temperature is about 95 RH% due to heat generated by the LED light source. When a conventionally used adhesive layer is used, adhesion of a layer having a concavo-convex structure on the surface to the substrate is not sufficient. Therefore, when it is used for a long period of time, bubbles are generated between layers having a concavo-convex structure on the surface of the substrate, or a layer having a concavo-convex structure on the surface is peeled off. However, as a result of intensive studies by the present inventors, such a problem can be solved by using a material having a storage elastic modulus G ′ at 100 ° C. of 40,000 to 180,000 Pa as a material constituting the adhesive layer. There was found.
The material constituting the adhesive layer is not limited except that the storage elastic modulus G ′ at 100 ° C. is 40,000 to 180,000 Pa, and generally used adhesives can be used. Examples of such adhesives include hot melt adhesives, thermosetting adhesives, pressure sensitive adhesives, energy ray curable adhesives, hygroscopic adhesives, dry adhesives, UV curable adhesives, Examples thereof include a polymerization type adhesive, a two-component reaction type adhesive, and an anaerobic type adhesive. Among these, a pressure-sensitive adhesive (adhesive) is most preferable from the viewpoint of workability.
In particular, according to the studies by the present inventors, when a pressure-sensitive adhesive having a storage elastic modulus G ′ at 100 ° C. of 40,000 to 180,000 is used, the substrate-adhesive layer and the adhesive layer-surface are used. It has been found that peeling between layers having a concavo-convex structure hardly occurs. Therefore, it is preferable to use such a material for the adhesive layer.
The storage elastic modulus at 100 ° C. of the material of the adhesive layer is more preferably 40,000 to 120,000 Pa, still more preferably 65,000 to 120,000 Pa, and particularly preferably 65,000 to 95,000 Pa. If the storage elastic modulus is too small, peeling or the like after sticking tends to occur, and if it is too large, the adhesiveness is inferior. Moreover, when the storage elastic modulus is too small, foaming occurs at the time of attachment when the substrate is an acrylic resin, which is not preferable.
The reason why peeling is difficult to occur when the storage elastic modulus G ′ at 100 ° C. is 40,000 to 180,000 Pa is not clear, but the high temperature resulting from the difference in coefficient of thermal expansion between the base material and the layer having an uneven structure on the surface. It is presumed that this is because the strain of time can be absorbed. However, the mechanism does not depend on this.

Here, the storage elastic modulus G ′ at 100 ° C. in the present invention means a value obtained by averaging the storage elastic modulus G ′ at 90 ° C. or more and less than 110 ° C. based on the results obtained by measurement under the following conditions. As the measuring device, for example, ARES manufactured by TA Instruments Inc. can be used.
-Deformation mode: Torsion-Measurement frequency: Constant frequency 1 Hz
-Rate of temperature increase: 5 ° C / min-Strain: 0.2%
・ Measurement temperature: Measured from near the glass transition temperature of the adhesive to 200 ℃ ・ Measurement part shape: Parallel plate 8mmφ
・ Sample thickness: 0.8-1mm
・ Pretreatment: Vacuum drying at a temperature of 50 ° C. and a degree of vacuum of −0.02 MPa for 30 minutes.

The storage elastic modulus G ′ at 100 ° C. in the present invention has a one-to-one correlation with the value (G ₀ ′) obtained in the same manner except that the following conditions are adopted as measurement conditions. Yes. The correspondence is shown in FIG .
Deformation mode: Torsion Measurement frequency: Constant frequency 1 rad / s
-Rate of temperature increase: 5 ° C / min-Strain: 2%
・ Measurement temperature: Measured from near the glass transition temperature of the adhesive to 200 ℃ ・ Measurement shape: Parallel plate 25mmφ
・ Sample thickness: 0.8-2mm
・ Pretreatment: None

In terms of optical properties, the material of the adhesive layer is preferably such that the total light transmittance of the adhesive layer is 90% or more and the haze is 1.0 or less.
Furthermore, since the adhesive layer is disposed in the vicinity of the light source when the light guide member is incorporated in a surface light source device, an illumination device, or the like, it is also preferable that the adhesive layer can withstand the influence of heat from the light source. .

  From the viewpoints described above, a preferable material for the adhesive layer is a (meth) acrylic pressure-sensitive adhesive (hereinafter simply referred to as “acrylic pressure-sensitive adhesive”) ((meth) acrylic polymer (as a monomer component (meth ) (Polymer containing acrylic acid) as a base polymer (preferably containing 30% by mass, more preferably containing 50% by mass or more)), urethane type adhesives, and rubber type adhesives.

Examples of the rubber-based adhesive include natural rubber, a copolymer of natural rubber and an acrylic component such as methyl methacrylate, a styrene block copolymer and a hydrogenated product thereof, and a styrene-butadiene-styrene block copolymer and Examples thereof include hydrogenated products. Among these, a copolymer of natural rubber and an acrylic component such as methyl methacrylate is preferable.
These may be used singly or in combination of two or more.

As an acrylic adhesive, what was manufactured with the below-mentioned method, a commercially available acrylic adhesive, etc. are mentioned.
Examples of commercially available acrylic adhesives include, for example, MO-3006C (manufactured by Lintec Corporation), MO-3012C (manufactured by Lintec Corporation), 8171 JR (manufactured by 3M Corporation), 8172 JR (3M Corporation). Manufactured), Panaclean PD-S1 (manufactured by Panac Co., Ltd.), MASTACK TR-1801 (manufactured by Fujimori Kogyo Co., Ltd.), MASTAK TR-1802 (manufactured by Fujimori Kogyo Co., Ltd.), CCL / D2-L / T5T5 (manufactured by Fujimori Kogyo Co., Ltd.) New Tac Kasei Co., Ltd.), CCL / D1 / T3T3 (New Tac Kasei Co., Ltd.), EXC10-076 (Toyo Ink Co., Ltd.), LUCIACS CS9621T (Nitto Denko Co., Ltd.), LUCIACS HJ9150W ( Nitto Denko Co., Ltd.), DH425A (manufactured by Sanei Kaken Co., Ltd.), and the like, but are not particularly limited thereto.
For example, when the layer having a concavo-convex structure on the surface is polyethylene terephthalate and the material of the base material is polymethyl methacrylate and used in an environment of 85 ° C., among the above-mentioned adhesives, PD-S1, TR-1801A, CCL / D1 / T3T3, MO-3006C, and EXC10-076 are preferable. The pressure-sensitive adhesive that can withstand even in a high temperature environment of 100 ° C. is PD-S1, TR-1801A, CCL / D1 / T3T3.

As a (meth) acrylic-type polymer which is a base polymer of an acrylic adhesive, for example, 0.1 to 10% by mass of a hydroxyl group-containing monomer or 0.1 to 10% by mass of a carboxyl group-containing monomer is copolymerized ( A (meth) acrylic polymer is particularly preferred.
Specific examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 6-hydroxyhexyl (meth) acrylate. Among these, it is preferable to use a hydroxyl group-containing monomer having 4 or more carbon atoms in the side chain because heat resistance is improved. These may be used singly or in combination of two or more.
The copolymerization ratio when using the hydroxyl group-containing monomer is preferably 0.1 to 10% by mass, and more preferably 0.3 to 7% by mass. If the content of the hydroxyl group-containing monomer is too small, the long-term durability may be lowered.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, itaconic acid, maleic acid and the like, and acrylic acid and methacrylic acid are particularly preferably used. These may be used singly or in combination of two or more. These carboxyl group-containing monomers are effective from the viewpoint of heat resistance due to improved adhesion and increased cohesive strength.
The copolymerization ratio of the carboxyl group-containing monomer is preferably 0.1 to 5% by mass, more preferably 0.2 to 3% by mass. If the amount of the carboxyl group-containing monomer is too small, the adhesiveness is inferior. If the amount is too large, the adhesive becomes hard and the durability may be inferior.

  In addition to these, as a monomer component of the (meth) acrylic polymer, a (meth) acrylic acid ester-based monomer having an alkyl group can be used. Examples of such (meth) acrylic acid ester monomers having an alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, Pentyl (meth) acrylate, isoamyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isomyristyl (Meth) acrylate and the like. These may be used singly or in combination of two or more. Among these, from the viewpoint of imparting flexibility to the pressure-sensitive adhesive, n-butyl (meth) acrylate is preferably used, and in that case, 30 to 99% by mass is preferably used in the (meth) acrylic polymer. More preferably, it is 50-99 mass%.

Furthermore, you may copolymerize suitably the other monomer (monomer component) which can be copolymerized with a (meth) acrylic-type polymer. Examples of the copolymerizable monomer include vinyl acetate, acrylamide, dimethylaminoalkylamide, acryloylmorpholine, glycidyl acrylate, styrene derivatives such as styrene and α-methylstyrene, and derivatives such as vinyltoluene and α-vinyltoluene. And high refractive index monomers, benzyl (meth) acrylate, naphthyl (meth) acrylate, phenoxyethyl (meth) acrylate, phenoxybutyl (meth) acrylate, and the like.

  In addition, as the (meth) acrylic polymer, in particular, a (meth) acrylic polymer containing 0.1 to 30% by mass of a carboxyl group-containing monomer and 30 to 99.9% by mass of n-butyl (meth) acrylate as a copolymerization component. Polymers are preferred, and those having a gel fraction adjusted to 30 to 90% by mass are preferred. As described above, the (meth) acrylic polymer can improve both the internal cohesive force and the flexibility of the adhesive layer, and therefore, when used by being bonded to the base material of the light guide member, No peeling from the material.

  The weight average molecular weight of the (meth) acrylic polymer is usually 600,000 or more, preferably 700,000 to 3,000,000. When the weight average molecular weight is too small, durability is poor, and when it is too large, workability is deteriorated.

The production of the (meth) acrylic polymer can employ any known production method such as solution polymerization, bulk polymerization, and emulsion polymerization.
For example, in solution polymerization, a polymerization initiator such as azobisisobutyronitrile (AIBN) is preferably used in an amount of 0.01 to 0.2 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer. More preferably, 0.05 to 0.15 parts by mass are used. It can be obtained by reacting at 50 to 70 ° C. for 8 to 30 hours under a nitrogen stream using a polymerization solvent such as ethyl acetate.

Modification treatment can also be performed for the purpose of adjusting the refractive index of the (meth) acrylic polymer thus obtained, increasing the internal cohesive force, and increasing the heat resistance.
As the modification treatment, for example, in the presence of 100 parts by mass of the (meth) acrylic polymer, a monomer different from the monomer component of the (meth) acrylic polymer is 10 to 200 parts by mass, preferably 10 to 100 parts by mass. In addition to the above, the medium may be adjusted as necessary, and a graft polymerization reaction may be performed using 0.02 to 5 parts by mass of peroxide, preferably 0.04 to 2 parts by mass.
Here, the monomer different from the monomer component of the (meth) acrylic polymer is not particularly limited, and benzyl (meth) acrylate, phenoxy (meth) acrylate, naphthyl (meth) acrylate, isobornyl (meth) acrylate High refractive index monomers such as (meth) acrylic acid ester monomers such as styrene derivatives such as styrene and α-methylstyrene, and derivatives such as vinyltoluene and α-vinyltoluene. By using the high refractive index monomer, the refractive index of the (meth) acrylic polymer can be increased.

As a graft polymerization method, in the case of solution polymerization, a necessary monomer and a solvent whose viscosity is adjusted are added to a solution of a (meth) acrylic polymer, followed by nitrogen substitution, and then a peroxide of 0.02 to 5 A part by mass, preferably 0.04 to 2 parts by mass, is added and heated at 50 to 80 ° C. for 4 to 15 hours to carry out a graft polymerization reaction.
If it is emulsion polymerization, add water to adjust the solid content to the aqueous dispersion of (meth) acrylic polymer, add the necessary monomer, and replace with nitrogen while stirring. After the monomer is absorbed into the polymer particles, a water-soluble peroxide aqueous solution is added, and the reaction is terminated by heating at 50 to 80 ° C. for 4 to 15 hours.
Thus, by polymerizing the monomer in the presence of the (meth) acrylic polymer, a homopolymer of this monomer is also produced, but graft polymerization to the (meth) acrylic polymer also occurs. The polymer consisting of the homopolymer is uniformly present in the acrylic copolymer. In this case, if the amount of peroxide used as an initiator is small, it takes too much time for the graft polymerization reaction, and if it is too large, a large amount of monomer homopolymer is generated.

In addition to a base polymer such as a (meth) acrylic polymer, a tackifier such as a tackifier may be appropriately added to the adhesive.
Although it does not specifically limit as said tackifier, A non-colored and transparent thing is preferable. The transparency is preferably a Gardner hue of 1 or less in a 50% by weight toluene solution.
As the tackifier, for example, a tackifier having an aromatic ring and having a refractive index in the range of 1.51 to 1.75 is preferably used. Moreover, it is preferable that the weight average molecular weights of a tackifier are 1000-3000, and it is preferable that a softening point is 90 degrees C or less. If the weight average molecular weight exceeds 3000 or the softening point exceeds 90 ° C., the compatibility with the (meth) acrylic polymer may be reduced, and if the weight average molecular weight is less than 1000, the cohesive strength of the adhesive May decrease.
Specifically, a styrene oligomer, a phenoxyethyl acrylate oligomer, a copolymer of styrene and α-methylstyrene, a copolymer of vinyltoluene and α-methylstyrene,
Examples thereof include hydrogenated products of C9 petroleum resins, hydrogenated products of terpene phenol, and hydrogenated products of rosin and its derivatives. At this time, a tackifier having a softening point of 40 ° C. or lower is used in combination with a use amount of less than 30 parts by mass and a tackifier having a softening point of 50 ° C. or higher being used in combination of 20 parts by mass or more. In terms of surface.
The amount of these tackifiers used is 10 to 150 parts by mass, preferably 20 to 100 parts by mass with respect to 100 parts by mass of the (meth) acrylic polymer solid content, and is adjusted to a predetermined refractive index. If the amount is too small, the refractive index will not increase sufficiently, and if it is too large, it will become hard and the adhesiveness will deteriorate, which is not preferable.

A crosslinking agent can be appropriately used for the pressure-sensitive adhesive. In particular, when a (meth) acrylic polymer is used as a base polymer, the cohesive force and durability are improved by crosslinking, which is preferable.
Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an oxazoline crosslinking agent, and a peroxide.
Diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diisocyanate adducts modified with various polyols, isocyanurate rings, burettes, and allophanates And a polyisocyanate compound in which is formed. In particular, aliphatic and alicyclic isocyanates are preferably used because the cross-linked product becomes transparent.
In addition, in an aqueous dispersion of a modified (meth) acrylic polymer produced by emulsion polymerization, an isocyanate crosslinking agent is often not used, but when used, the isocyanate group easily reacts with water. An isocyanate-based cross-linking agent may be used.

As the peroxide, any peroxide can be used as long as it generates radicals by heating to advance the crosslinking of the base polymer of the pressure-sensitive adhesive. For example, di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxyneodecanoate, t-hexyl Peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di ( 4-methylbenzoyl) peroxide, dibenzoyl peroxide, t-butylperoxyisobutyrate, 1,1-di (t-hexylperoxy) cyclohexane and the like. Among these, di (4-t-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, dibenzoyl peroxide, and the like are preferably used because of particularly excellent crosslinking reaction efficiency.
The peroxide may be used alone, or two or more kinds may be mixed and used, but the total content is 0.1% of the peroxide with respect to 100 parts by mass of the base polymer. It is preferable to contain 03-2 mass parts, it is more preferable to contain 0.04-1.5 mass parts, and it is still more preferable to contain 0.05-1 mass part. If the amount is less than 0.03 parts by mass, the cohesive force may be insufficient. On the other hand, if the amount exceeds 2 parts by mass, the crosslinking may be excessively formed and the adhesiveness may be poor.

  However, when an aromatic isocyanate compound is used as a cross-linking agent, the cured adhesive may be colored, so the application of the present invention requiring light transparency (light guide member) In this case, aliphatic or alicyclic isocyanates are preferably used.

  As a compounding quantity of the above crosslinking agents, although it changes also with kinds of (meth) acrylic-type polymer to be used, it is 0.03-2 mass parts normally with respect to 100 mass parts of (meth) acrylic-type polymers, Preferably Is used in the range of 0.05 to 1 part by mass. When the amount is too small, the cohesive force is insufficient, and when the amount is too large, the adhesiveness is lowered, which is not preferable.

Moreover, a silane coupling agent can be suitably added to an adhesive.
Examples of the silane coupling agent include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2- (3,4-epoxycyclohexyl). Epoxy group-containing silane coupling agents such as ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1, (3-dimethylbutylidene) propylamine, amino group-containing silane coupling agents such as N-phenyl-3-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane ( (Meth) acrylic group-containing Silane coupling agents, such as Inshianeto group-containing silane coupling agents such as 3-isocyanate propyl triethoxysilane and the like. Use of such a silane coupling agent is preferable for improving the durability of the pressure-sensitive adhesive. Moreover, the adhesiveness with respect to the glass base material of an adhesive is also improved.
The silane coupling agent may be used alone or in combination of two or more, but the total content is 100 parts by weight of the (meth) acrylic polymer. It is preferable to contain 0.01-2 mass parts of silane coupling agents, and it is more preferable to contain 0.02-1 mass parts. If the amount is less than 0.01 part by mass, the durability improving effect may be inferior. On the other hand, if the amount exceeds 2 parts by mass, the adhesive force may increase excessively and the removability may be inferior.

  The adhesive may contain an organic solvent in a very small amount, such as methanol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, cyclohexanol, benzyl alcohol, ethyl ether, 1,4-dioxane, Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, chloroform, toluene, m-xylene, p-xylene, o-xylene, n-hexane, cyclohexane, methyl acetate, ethyl acetate , Isopropyl acetate, propyl acetate, isobutyl acetate, butyl acetate, pentyl acetate (amyl acetate), isopentyl acetate, acetone, methyl ethyl ketone (MEK), cyclohexanone, , N- dimethylformamide (DMF), dimethylsulfoxide (DMSO) or the like is used is not particularly limited. These organic solvents are preferably contained in an amount of 0.001 to 1 part by weight, more preferably 0.001 to 0.5 parts by weight, and more preferably 0.001 to 0.005 parts per 100 parts by weight of the (meth) acrylic polymer. It is more preferable to contain 1 part by mass. If it is contained in an amount of more than 1 part by mass, the organic solvent generated from the pressure-sensitive adhesive may dissolve a substrate or a layer having a concavo-convex structure on the surface, which is not preferable. On the other hand, when it contains less than 0.001 part by mass, drying time and drying cost may be required.

  The pressure-sensitive adhesive may contain other known additives such as vulcanizing agents, tackifiers, colorants, pigments and other powders, dyes, surfactants, plasticizers, surface lubricants. Depending on the use of leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, foils, etc. Can be added as appropriate. Moreover, you may employ | adopt the redox type | system | group which added the reducing agent within the controllable range.

In addition, the adhesive can be prepared in the form of being laminated on the support that has been subjected to the peeling treatment when the light guide member is manufactured. For example, the pressure-sensitive adhesive can be coated, dried and cross-linked onto a release-treated support to obtain a sheet with a pressure-sensitive adhesive layer. Specifically, a pressure-sensitive adhesive is applied and dried on a release-treated support, and a release-treated film having a relatively low peel strength is bonded thereon to produce a sheet with a pressure-sensitive adhesive. Alternatively, the pressure-sensitive adhesive may be applied and dried on the support that has been subjected to the peeling treatment, and then immediately bonded to the substrate.
As such a support material, for example, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, acrylic resins such as polymethyl methacrylate, thermoplastic resins such as polycarbonate resin, polystyrene resin, polymethylpentene resin, Transparent base material composed of a resin obtained by curing an ionizing radiation curable resin composed of an oligomer such as polyester acrylate, urethane acrylate, epoxy acrylate and / or an acrylate monomer with electromagnetic radiation such as ultraviolet rays or electron beams, etc. However, polyethylene terephthalate is generally used from the viewpoint of economy. Moreover, as a peeling process, a silicone layer is apply | coated or an emboss shape is provided.
The pressure-sensitive adhesive is applied by any coating method such as reverse coater, comma coater, lip coater, die coater, etc., so that the thickness of the pressure-sensitive adhesive after drying is usually 2 to 500 μm, preferably 5 to 100 μm. Is done.

When the pressure-sensitive adhesive contains a crosslinking agent, the gel fraction of the pressure-sensitive adhesive after crosslinking is 30 to 90% by mass, preferably 40 to 90% by mass, more preferably after coating and drying on the release-treated support. May be crosslinked so as to be 45 to 85% by mass.
If the gel fraction is too small, the cohesive force is inferior, and if it is too large, it is not preferable because the adhesiveness is inferior. Even if the monomer is generated, the foaming phenomenon at the adhesive interface between the substrate and the pressure-sensitive adhesive can be suppressed. Here, the gel fraction of the pressure-sensitive adhesive refers to the ratio of the pressure-sensitive adhesive that does not dissolve in ethyl acetate, and is an index indicating the ratio (% by mass) of the crosslinked one.
(Measurement of gel fraction)
The gel fraction can be measured as follows.
W ₁ g of the pressure-sensitive adhesive was taken out and immersed in ethyl acetate at room temperature (about 25 ° C.) for 7 days. Then, the pressure-sensitive adhesive (insoluble matter) subjected to the immersion treatment was taken out from ethyl acetate, and the mass W ₂ g after drying at 130 ° C. for 2 hours was measured. Gel fraction is gel fraction (mass%) = (W ₂ / W ₁ ) × 100
As calculated.

The displacement of TMA (thermomechanical analysis) at 100 ° C. of the material constituting the adhesive layer is preferably in the range of −1 to 2 μm, more preferably 0 to 1 μm, still more preferably 0 to 0.5 μm. is there. If the displacement of the TMA is too small, peeling or the like after sticking is likely to occur, and if it is too large, undulation is caused by heat, which is not preferable.
(Measurement of thermal mechanical analysis (TMA) displacement)
Thermomechanical analysis was performed under the following conditions.
・ Device: Seiko Instruments TMA / SS120
-Probe: Needle-in probe (tip diameter: 1 mm)
・ Load: 10mN (1.02g)
・ Atmosphere: Air ・ Temperature range: 30 to 200 ° C
Temperature rising time: 5 ° C./minute Measurement sample: 25 μm-thick adhesive layer was cut into 5 mm square and attached to a quartz disk (10 mmφ).

The TG / DTA (weight reduction rate) at 100 ° C. of the material constituting the adhesive layer is preferably in the range of 0 to −0.4%, more preferably 0 to −0.3%, still more preferably. Is 0 to -0.2%. If the TGA is too large, the adhesive layer is deteriorated by heat, which is not preferable.
(Measurement of thermogravimetric analysis)
Thermogravimetric analysis was performed under the following conditions.
・ Device: TG / DTA220 manufactured by Seiko Instruments Inc.
・ Atmosphere: Nitrogen (Flow rate: 250ml / min)
-Temperature range: 30 ° C to 200 ° C
Temperature rising time: 10 ° C./min Sample preparation: An adhesive layer having a thickness of 25 μm was folded so that the total mass was 10 mg and set in a sample container.

The peel strength of the material constituting the adhesive layer is preferably in the range of 0.3 to 1.5 N / mm, more preferably 0.4 to 1.2 N / mm, still more preferably 0.5 to 1.N. 0 N / mm. If the peel strength is too low, peeling or the like after sticking is likely to occur.
(Measurement of peel strength)
The peel strength was measured under the following conditions.
Apparatus: RTG-1210 manufactured by A & D
・ Peeling angle: 90 °
・ Peeling speed: 50 mm / min
・ Measurement distance: 50mm
Test environment: temperature 23 ° C, humidity 50%
-Adhesive sample: After affixing an adhesive layer to a polyethylene terephthalate film (Toyobo Cosmo Shine A4300, 75 μm thickness), the width was cut to 3.5 mm, and an acrylic plate (Kanase Industries, Kanaselite 1300, thickness: 2 mm, size 25 cm × 3 cm) and left for 1 day in an environment of temperature 23 ° C. and humidity 50% was used as a measurement sample.

The refractive index of the material constituting the adhesive layer is preferably in the range of 1.40 to 1.70, more preferably 1.45 to 1.65, and still more preferably 1.45 to 1.60.
(Measurement of refractive index)
The refractive index was measured under the following conditions.
Under an atmosphere of 25 ° C., sodium D line (589 nm) was irradiated, and the refractive index was measured using an Abbe refractometer (manufactured by ATAGO, DR = M4).

  The thickness of the adhesive layer is not limited. For example, the adhesive layer may be adjusted so that the total light transmittance of the adhesive layer is 90% or more and the haze is 1.0 or less, but the thickness of the adhesive layer is 5 to 200 μm. It is preferable because peeling between the base material and the adhesive layer and between the adhesive layer and the layer having a concavo-convex structure on the surface is unlikely to occur. The thickness of the adhesive layer is more preferably 10 to 100 μm, further preferably 15 to 50 μm, and further preferably 20 to 30 μm. If the thickness of the adhesive layer is too thin, if the substrate has fine irregularities, the adhesive layer cannot follow the irregularities (cannot absorb the irregularities), increasing the probability of poor bonding. To do. On the other hand, if the thickness of the adhesive layer is too large, the area of the cross section becomes large, so that the probability of occurrence of problems such as sticking out of the adhesive and occurrence of lumps increases during the manufacture of the light guide plate. Further, if the thickness of the adhesive layer is too thick, there is also a disadvantage that the length that can be wound around the same roll diameter is shortened when the adhesive layer is handled in a roll shape in the manufacturing process.

  One or more fine grooves are formed on the surface of the adhesive layer on the side in contact with the base material so that air bubbles generated between the base material and the adhesive layer escape when the light guide plate is used under high temperature and high humidity. It may be formed. There is no limitation on the width, cross-sectional shape, depth, and the like of such a groove, but the width is preferably 0.5 mm or less, more preferably 0.3 to 0.01 mm. Moreover, the depth can be 0.5-0.01 mm, for example. The length of the groove is not limited, but it is preferable that the groove is crossed or vertically cut.

Next, a layer having a concavo-convex structure on the surface will be described.
Although the thickness of the layer having a concavo-convex structure on the surface is not limited, it is preferably about 25 to 500 μm from the viewpoint of adhesiveness with the adhesive layer. If it is too thin, the stiffness will be insufficient, and the workability at the time of pasting on the substrate will be reduced. On the other hand, if it is too thick, the stiffness will be too strong and the workability of pasting will be reduced. It is more preferable that

The layer having a concavo-convex structure on the surface may have a multilayer structure including a transparent base film layer and a resin layer having a plurality of concave portions or convex portions on the surface laminated thereon.
In this case, the material of the resin layer having a concavo-convex structure on the surface is not limited, and examples thereof include a cured product of a photopolymerizable resin composition.
The material and thickness of the transparent base film layer are not limited, and examples of the material include highly transparent materials such as polyethylene terephthalate, polycarbonate, and polystyrene (for example, the total light transmittance is 90% or more, and the haze is 1). 0.0 or less), and the thickness can be, for example, 20 to 250 μm, more preferably 50 to 125 μm.

  The photopolymerizable resin composition is the same as the resin layer of the diffusion sheet of the first invention of the present specification described later, that is, (A) an addition polymerizable monomer having at least one terminal ethylenically unsaturated group. It is preferable to use those containing 70 to 99.9% by mass and (B) a photopolymerization initiator: 0.1 to 30% by mass.

  (A) As an addition polymerizable monomer having at least one terminal ethylenically unsaturated group, for example, a compound represented by the following general formula (I) having a biphenyl group can be used.

Formula (I)

(In general formula (I), R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.)

The compound having the structure represented by the general formula (I) is a compound in which the substitution position of the biphenyl group is an ortho position or a para position, and X is a divalent organic group having 1 to 12 carbon atoms. Preferably, it is a compound represented by the following general formula (II).
In general formula (II), R represents a hydrogen atom or a methyl group, A independently represents an alkylene group having 1 to 4 carbon atoms, and n represents an integer of 1 to 3.

Formula (II)

In addition, as the addition polymerizable monomer (A) having at least one terminal ethylenically unsaturated group, in addition to the compound represented by the above general formula (I), a compound having a known (meth) acrylate group or allyl group Can also be used.
For example, nonylphenol acrylate, alkoxylation (1) o-phenylphenol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, β-hydroxypropyl-β ′-(acryloyloxy) propyl phthalate, 1,4-tetramethylene glycol di ( (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, octapropylene glycol di (meth) acrylate, glycerol (meth) acrylate, 2-di (p-hydroxy) Phenyl) propane di (meth) acrylate, glycerol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, polyoxypropyltrimethylolpropane tri (meth) acrylate Polyoxyethyltrimethylolpropane tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane triglycidyl ether tri (meth) acrylate, bisphenol A diglycidyl ether di (Meth) acrylate, diallyl phthalate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, bis (triethylene glycol methacrylate) nonapropylene glycol, bis (tetraethylene glycol methacrylate) polypropylene glycol, bis (triethylene glycol) Methacrylate) polypropylene glycol, bisarylfluorene derivatives, bis (diethyl) (Lene glycol acrylate) polypropylene glycol, compounds containing both ethylene oxide chain and propylene oxide chain in the molecule of bisphenol A (meth) acrylate monomer. Among these, alkoxylated (1) o-phenylphenol acrylate is preferable from the viewpoint of refractive index, and ethoxylated (1) o-phenylphenol acrylate (for example, product name A-LEN-10, manufactured by Shin-Nakamura Chemical Co., Ltd.) is particularly preferable. preferable.
A urethanized compound of a polyvalent isocyanate compound such as hexamethylene diisocyanate or tolylene diisocyanate and a hydroxy acrylate compound such as 2-hydroxypropyl (meth) acrylate can also be used.
The urethanized compound in this case is preferably less than 10,000 in terms of polystyrene-reduced number average molecular weight by gel permeation chromatography (GPC).
The above-mentioned (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group may be used alone or in combination of two or more.

The content of the (A) addition polymerizable monomer in the photopolymerizable resin composition is preferably 70% by mass or more and 99.9% by mass or less based on the total mass of the photopolymerizable resin composition, and more preferably. Is 75 mass% or more and 95 mass% or less. From the viewpoint of sufficient curing, it is preferably 70% by mass or more, but it is preferably 99.9% by mass or less in consideration of blending an initiator component, other polymerization inhibitor, dye, and the like.
Moreover, it is preferable that the content rate of the compound represented by the said general formula (I) is 50-95 mass%. From the viewpoint of increasing the refractive index of the resin layer, 50% by mass or more is preferable, and from the viewpoint of preventing a decrease in photocurability, the content is preferably 95% by mass or less.

Examples of the photopolymerization initiator (B) in the photopolymerizable resin composition include benzyl dimethyl ketal, benzyl diethyl ketal, benzyl dipropyl ketal, benzyl diphenyl ketal, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, Benzoin phenyl ether, thioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diisopropylthioxanthone, 2-fluorothioxanthone, 4-fluorothioxanthone, 2-chloro Thioxanthone, 4-chlorothioxanthone, 1-chloro-4-propoxythioxanthone, benzophenone, 4,4'-bis (dimethylamino) benzofe Aromatic ketones such as non [Michler's ketone], 4,4′-bis (diethylamino) benzophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one , Biimidazole compounds such as 2- (o-chlorophenyl) -4,5-diphenylimidazolyl dimer, acridines such as 9-phenylacridine, α, α-dimethoxy-α-morpholino-methylthiophenylacetophenone, 2,4 , 6-trimethylbenzoyldiphenylphosphine oxide, phenylglycine, N-phenylglycine, 1-phenyl-1,2-propanedione-2-O-benzoyloxime, ethyl 2,3-dioxo-3-phenylpropionate 2- (O-benzoylcarbonyl) -oxime Oxime esters such as p-dimethylaminobenzoic acid, p-diethylaminobenzoic acid, and p-diisopropylaminobenzoic acid, and esterified products thereof with these alcohols, p-hydroxybenzoic acid ester, 3-mercapto-1,2 Triazoles such as 1,4-triazole, tetrazoles, N-phenylglycine, N-phenyl-N-phenylglycine, N-phenylglycine such as N-ethyl-N-phenylglycine, and 1-phenyl-3- Styryl-5-phenyl-pyrazoline, 1- (4-tert-butyl-phenyl) -3-styryl-5-phenyl-pyrazoline, 1-phenyl-3- (4-tert-butyl-styryl) -5- (4 And pyrazolines such as -tert-butyl-phenyl) -pyrazoline.
Among these, 2-hydroxy-2-methyl-1-phenyl-propan-1-one (for example, product name DAROCURE 1173, manufactured by Ciba Specialty Chemical) is preferable.

The content of the photopolymerization initiator (B) in the photopolymerizable resin composition is preferably 0.1% by mass or more and 30% by mass or less based on the total mass of the photopolymerizable resin composition, and more preferably. Is 1 mass% or more and 20 mass% or less.
When the content of (B) is 0.1% by mass or more, sufficient photocuring sensitivity is obtained, and when it is 30% by mass or less, storage stability as a liquid resin before photocuring is obtained.

In order to improve thermal stability and storage stability, it is preferable to contain a radical polymerization inhibitor in the photopolymerizable resin composition.
Examples of such radical polymerization inhibitors include p-methoxyphenol, hydroquinone, pyrogallol, naphthylamine, t-butylcatechol, cuprous chloride, 2,6-di-t-butyl-p-cresol, 2,2 Examples include '-methylenebis (4-ethyl-6-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), and the like.
The content of the radical polymerization inhibitor is preferably 0.001% by mass or more and 1% by mass or less based on the total mass of the photopolymerizable resin composition.
The photopolymerization resin composition may contain an organic solvent in a small amount. For example, methanol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, cyclohexanol, benzyl alcohol, ethyl ether, 1, 4 -Dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, chloroform, toluene, m-xylene, p-xylene, o-xylene, n-hexane, cyclohexane, methyl acetate , Ethyl acetate, isopropyl acetate, propyl acetate, isobutyl acetate, butyl acetate, pentyl acetate (amyl acetate), isopentyl acetate, acetone, methyl ethyl ketone (MEK), cyclohexane Sanon, N, N-dimethylformamide (DMF), dimethylsulfoxide (DMSO) or the like is used is not particularly limited. These organic solvents are preferably contained in an amount of 0.001 to 1 part by mass, more preferably 0.001 to 0.5 part by mass, and even more preferably 0.001 to 0.1 part by mass. If it is contained in an amount of 1 part by mass or more, other materials in contact with the organic solvent generated from the photopolymerization resin composition may be dissolved, which is not preferable. When it contains less than 0.001 part by mass, it is not preferable because it takes a drying time and a drying cost.

The refractive index of the photopolymerizable resin composition after curing is preferably in the range of 1.40 to 1.70, more preferably 1.45 to 1.65, still more preferably 1.45 to 1.60. .
When the refractive index is lower than 1.40, when the light guide plate of the present invention is used as a surface light source device, the ability of the resin layer having a concavo-convex structure on the surface to uniform the luminance unevenness derived from the light source decreases. If the refractive index is higher than 1.70, the production becomes difficult.
(Measurement of refractive index)
The refractive index was measured under the following conditions.
Under an atmosphere of 25 ° C., sodium D line (589 nm) was irradiated, and the refractive index was measured using an Abbe refractometer (manufactured by ATAGO, DR = M4).

As for the thickness of the resin layer having a concavo-convex structure on the surface, the concavo-convex structure cannot be formed if it is too thin. There is also a possibility that discoloration when left for a long time exceeds the allowable range. From such a viewpoint, the thickness can be set to 2 to 50 μm.
In addition, in order to improve optical performance, the resin layer having an uneven structure on the surface can be mixed with, for example, silicon fine particles having an average particle diameter of about 2 μm to give internal diffusion performance. In the embodiment, an ultraviolet curable resin having no such internal diffusion performance is used.

  In the light guide plate of the present invention, there may be at least one light incident surface, and there may be two or more. When two light incident surfaces are provided, the shape of the light guide plate is preferably a flat rectangular parallelepiped having a light exit surface and an opposite surface as a main surface, and the two light incident surfaces are preferably opposed to each other. In this case, since two opposing light incident surfaces have the same length, there is a merit that the number and type of point light sources can be made the same and parts can be shared.

  Although there is no limitation on the thickness of the light guide plate (the distance between the light exit surface and the facing surface facing this), it can be, for example, about 2.0 to 5.0 mm.

  The material of the light guide plate of the present invention is not particularly limited as long as it is translucent. For example, it is generally used as a material for optical parts such as polymethyl methacrylate, polycarbonate, polystyrene, and methyl methacrylate-styrene copolymer. A highly transparent polymer material or an inorganic material such as glass can be used.

  In addition, the light guide plate of the present invention includes organic and inorganic dyes and pigments, matting agents, heat stabilizers, flame retardants, antistatic agents, antifoaming agents, color stabilizers, antioxidants, UV absorption as necessary. An additive such as an agent, an impurity scavenger, a thickener, a surface conditioner, and a release agent may be contained within a range not impairing the object of the present invention.

  The concavo-convex structure (plurality of concave portions or convex portions) in the light guide plate of the present invention has an anisotropic shape in which the openings (bottom surfaces) of the plural concave portions (convex portions) are long in a specific direction. Depending on the surface shape, the diffusion angle in the direction perpendicular to the specific one direction (that is, the major axis direction of the opening (bottom surface) of the concave portion (convex portion)) is the maximum, and the direction parallel to the specific one direction An anisotropic diffusion characteristic with a minimum diffusion angle is shown.

The specific value of the diffusion angle (the diffusion angle (FWHM) of the emitted light when a light beam is incident on the light incident surface perpendicularly) is not limited, but the direction perpendicular to the specific one direction (parallel to the light output surface). The diffusion angle in the right direction) is preferably 30 ° or more, more preferably 40 ° or more, still more preferably 50 ° or more, and particularly preferably 65 ° or more. Moreover, it is preferable that the upper limit is 120 degrees or less, 100 degrees or less may be sufficient, and 90 degrees or less may be sufficient.
On the other hand, the diffusion angle in the one specific direction (direction perpendicular to the light exit surface) is recommended to be 10 ° or less, preferably 5 ° or less, more preferably 1 ° or less, Most preferably 0.5 ° or less.

  The ratio of the maximum value to the minimum value of the diffusion angle is preferably 200 or more, and more preferably 400 or more. By making the ratio of the maximum value to the minimum value of the diffusion angle in such a range, luminance unevenness can be further reduced. Note that the ratio of the maximum value to the minimum value of the diffusion angle will be described in detail in the description related to the third invention of the specification to be described later.

  Both the diffusion angle in the direction perpendicular to the specific direction and the direction parallel to the specific direction can be adjusted by appropriately changing the shape, depth (height), pitch, and the like of each recess (projection). When the groove structure is formed using the speckle pattern, these can be adjusted by appropriately changing the conditions for diffusing the laser beam.

  Except in the case of the second invention described below, the diffusion characteristics are preferably substantially constant over the entire region where the concavo-convex structure is formed.

Here, the “diffusion angle” refers to an angle (FWHM: Full Width Half Maximum) that is twice the angle (half-value angle) at which the transmitted light intensity attenuates to half of the peak intensity (see FIG. 8). This diffusion angle can be measured by, for example, Photon Inc. Transmission of light incident on the concavo-convex structure from the normal direction of the surface on which the concavo-convex structure is formed, using a variable angle color difference meter such as Photon or Beam Profiler NanoScan made by Nippon Denshoku Industries Co., Ltd. It can be obtained by measuring the angular distribution of light intensity (distribution of the intensity of transmitted light with respect to the emission angle). In particular, NanoScan is most suitable for measurement with respect to the characteristics with FWHM of 1 ° or less. Here, the normal direction of the surface on which the concavo-convex structure is formed refers to the direction indicated by 16 in FIG.
In addition, the definition of the diffusion angle is that the angle distribution of transmitted light intensity has a maximum peak near 0 degrees,
The definition is based on the assumption that the peak decreases monotonously on both sides of the maximum peak.
In the case where (1) the maximum peak is other than the center, or (2) peaky transmission intensity exists at a specific angle, that is, there is a peak whose maximum peak width (root width) is 10 ° or less. In light of the purpose of the main body that defines the diffusion angle, (1) the half-value width of the transmitted light intensity value near 0 degrees is applied, and (2) the transmission intensity obtained by taking a moving average in the range of ± 15 °. The full width at half maximum will be applied.

Note that the diffusion angle is theoretically (Snell's law), and if the substrate does not have internal diffusion performance, it is not affected by the refractive index of the substrate and is a material that forms the surface on which the concavo-convex structure is formed. Depends on refractive index. For this reason, if the manufacturing method of (3) above is adopted as a method for forming the concavo-convex structure on the light incident surface of the light guide plate, even if the diffusion angle is measured with the film having the concavo-convex structure alone, this is used as the light guide plate. Even if the diffusion angle is measured in the state of the final form bonded together, the measurement result does not change.
Further, if the production methods (1) and (2) are adopted, a thin piece cut by a plane parallel to the light incident surface may be produced and the diffusion angle thereof may be measured.

  In addition, when the surface facing the surface to be measured is not smooth, the surface is made smooth by cutting or the like, or the surface shape of the surface to be measured is the same refraction as the material forming the surface It can be measured by transferring to a material having a rate and using this (even if the irregularities are inverted, the angular distribution of transmitted light intensity incident from the 0 degree direction does not change, and thus the diffusion angle does not change).

  Further, when a light beam is incident on the light incident surface on which the concavo-convex structure is formed from the normal direction, the transmitted light intensity of the light is preferably 90% or more of the peak intensity at the emission angle = 0 °. .

Specific examples are shown in FIGS. 15A and 15B. FIGS. 15A and 15B are angular distributions of transmitted light intensity of a film having a concavo-convex structure alone, measured using a GC5000L manufactured by Nippon Denshoku Industries Co., Ltd.
The transmitted light intensity in the ◇ (outlined) portion in the figure is 90% or more of the peak intensity. In either angular distribution, the transmitted light intensity is 90% or more of the peak intensity at the emission angle = 0 °.
As described above, the surface shape of the light incident surface on which the concavo-convex structure is formed is such that the angular distribution of the transmitted light intensity of light when a light beam is incident from the normal direction does not have a plurality of peaks and changes gently. It is preferable that it is such.

  In the light guide plate of the present invention, it is presumed that the effect of reducing luminance unevenness such as hot spots is improved by the anisotropic diffusion characteristics derived from the surface shape of the plurality of concave portions or convex portions as described above.

  The anisotropic diffusion characteristic is also used in the technique disclosed in Patent Document 5, but it is difficult to obtain highly accurate anisotropy by the method of dispersing the filler. The diffusion angle in the direction cannot be maximized. When such a member having low accuracy of anisotropy is provided on the light incident surface, the light guide efficiency is deteriorated. Furthermore, light leakage immediately after entering the light guide plate becomes severe due to insufficient anisotropy, and quality suitable for display devices and surface light source devices cannot be obtained. In addition, in the technique disclosed in Patent Document 5, anisotropy is imparted using refraction between the pressure-sensitive adhesive and the filler. Since the difference in refractive index between the two is small, the light guide plate moves in one direction. The diffusion angle cannot be made sufficiently large.

  In contrast, in the light guide plate of the present invention, anisotropic diffusion characteristics are realized by the surface shape of the concavo-convex structure. By controlling the surface shape, highly accurate anisotropic diffusion characteristics can be stabilized. Can get to. Furthermore, in the present invention that realizes anisotropic diffusion characteristics by the surface shape, refraction that causes anisotropic diffusion is a material (resin or resin composition) that forms an uneven structure with air (refractive index of approximately 1) ( The refractive index is about 1.3 to 1.6), and compared with the technique disclosed in Patent Document 5 that utilizes the refraction between the adhesive and the filler, the opening of the recess (convex) The diffusion angle in the direction perpendicular to the major axis direction of the (bottom surface) can be set to a large value.

When the light incident surface of the light guide plate of the present invention further satisfies the following requirements, the luminance unevenness is further reduced.
The entire light incident surface has anisotropic light diffusion characteristics in which the diffusion angle of incident light from the normal direction in the longitudinal direction of the incident surface is greater than the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface. ,
The light emission pattern curve of the entire light incident surface with the horizontal axis representing the emission angle of the light emitted from the normal direction of the light incident surface in the longitudinal direction of the light incident surface and the vertical axis representing the intensity appears in the light emission pattern curve. When compared with a normal distribution curve passing through a total of three points: one peak point where the intensity of the emitted light is the peak intensity and two intermediate points where the intensity of the emitted light is half of the peak intensity, the following conditions 1. And / or condition 2. Meet.
Condition 1. The range of the emission angle where the intensity of the emitted light is 3/4 or more of the peak intensity is narrower than the normal distribution curve.
Condition 2. The range of the emission angle where the intensity of the emitted light is 1/10 or more of the peak intensity is wider than the normal distribution curve.
Such a requirement will be described in detail in the description related to the second invention of the specification below.

Next, the light output surface and the opposing surface of the light guide plate of the present invention will be described.
A groove structure substantially parallel to the normal direction of the light incident surface can be provided on the light exit surface and / or the opposite surface of the light guide plate of the present invention. Providing such a groove structure on the light exit surface can improve the straightness that suppresses the spread of the light emitted from the light exit surface, so that the light guide plate can be suitable for local dimming.
The groove structure is preferably a lenticular lens shape or a plurality of random grooves. Whether the groove structure is provided on the light exit surface or the facing surface may be appropriately determined in consideration of ease of manufacture, ease of handling, and the like. Although it may be provided on both the light exit surface and the facing surface, for example, when the light scattering processing described later is provided on the facing surface, it is preferably provided only on the light exiting surface.
Furthermore, from the viewpoint of reducing hot spots in the area near the light incident surface, the groove structure starts from a position 1 to 50 mm inside from the light incident surface side end of the light exit surface and / or the opposite surface. It is preferable to provide it so that it may extend in the opposite direction.

The lenticular lens shape preferably extends in a direction substantially parallel to the normal direction of the light incident surface and is provided in parallel. The pitch of the lenticular lens shape is preferably 20 to 500 μm, and the depth is preferably 20 to 500 μm (see FIG. 118 ). If the pitch is too small, accurate processing of the lenticular lens is difficult, and if the pitch is too large, moire between the pixels of the liquid crystal panel is likely to occur. If the depth is too shallow, the straightness of light decreases, and if the depth is too deep, accurate machining becomes difficult or easily damaged.

Next, a plurality of random grooves will be described.
That the plurality of grooves are random means that at least one of the cross-sectional shape, pitch, and depth of the plurality of grooves is randomly (irregularly) different.
FIG. 118 shows an example in which a plurality of random grooves substantially parallel to the normal direction of the light incident surface are provided on the light exit surface.

There is no limitation in the cross-sectional shape of each groove | channel, For example, it can be set as V shape or U shape.
The pitch of the grooves refers to a horizontal distance between the valley bottoms of adjacent grooves (a horizontal distance in a direction parallel to a surface having a plurality of random grooves). When the valley bottom is flat, the pitch is determined with the center as the valley bottom. The cross-sectional shape and width of the groove may change along the extending direction of the groove.
The depth of the groove is the vertical distance between the peak of the higher peak of the peaks on both sides of each groove and the valley bottom of the groove (distance in the direction perpendicular to the surface having a plurality of random grooves). (Elevation difference between mountain top and valley bottom).
The depth of the groove may change gently or steeply along the extending direction, and as a result, there may be a portion where the groove is interrupted, but it is preferable that it does not change if possible.
Specific examples of the random plurality of grooves which can be preferably used in the present invention shown in FIGS. 120 A and FIG. 120 B. FIG. 120A shows a specific example of a plurality of random grooves having anisotropic light diffusion characteristics in which a diffusion angle in a direction perpendicular to the groove (described later) is 30 degrees and a diffusion angle in a direction horizontal to the groove is 1 degree. It is a surface profile figure which shows an example. FIG. 120B shows a specific example of a plurality of random grooves having anisotropic light diffusion characteristics in which the diffusion angle in the direction perpendicular to the grooves is 60 degrees and the diffusion angle in the direction horizontal to the grooves is 1 degree. It is a surface profile figure.

The average pitch of a plurality of random grooves is not limited, but is preferably 30 μm or less, more preferably 20 μm or less, still more preferably 15 μm or less, and particularly preferably 10 μm or less. The average pitch of the plurality of random grooves is preferably 580 nm (the central wavelength of visible light) or more, more preferably 780 nm (the entire visible light region) or more.
Since the pixel pitch of the display panel used in combination with the light guide plate and the structure pitch of the optical sheet are approximately 100 to 600 μm and 50 to 150 μm, respectively, the average pitch of a plurality of random grooves is set to such a value. If set, generation of moire due to spatial interference with a display panel or an optical sheet used in combination with the light guide plate can be prevented. Furthermore, if the average pitch is set to such a value, the claw and the like are not easily caught in the groove during handling, and handling is improved. Furthermore, since the light guided by the light guide plate of the present invention is visible light (an electromagnetic wave of 380 nm to 780 nm), in order to sufficiently exhibit the effect of direct evolution of light by a plurality of random grooves, the average pitch is The lower limit is preferably a value as described above.
The average depth of the plurality of random grooves is not limited, but is preferably 1 to 50 μm, more preferably 5 to 10 μm.

The slope angle of the groove has a great influence on the straightness of light. In other words, when a groove structure is provided on the light exit surface or the opposite surface, light that spreads outward in the light guide plate is reflected by the slope of the groove and returned to the light guide plate, thereby improving the straightness of the light. It is done. Therefore, the slope angle of each groove is preferably 40 to 60 degrees. Accordingly, it is preferable that the proportion of the plurality of random grooves provided on the light exit surface or the opposing surface is within a range of 40 degrees to 60 degrees of the slope angle of the grooves is 5% or more. More preferably, it is 10% or more. Of these, the greater the proportion occupied by 45 ± 5 degrees contributes to the improvement in straightness.
Here, the “slope angle” is a general term for an angle formed by a surface tangent to each groove and a surface having a groove structure in a cross section perpendicular to the groove of a surface having a plurality of random grooves.
And about the ratio which a slope angle has in the range of 40 degree-60 degree | times, the arbitrary perpendicular | vertical of the surface which has a random several groove | channel by microscope observation (a scanning electron microscope, a laser confocal microscope, etc.) A range with a distance of 300 μm is extracted arbitrarily from the cross section (cross section perpendicular to the groove structure), and tangents with points at 0.5 μm points from the end of the range are extracted. It is determined by measuring an angle (acute angle) formed by the surface having the groove.

In addition, a light scattering process having a gradation toward the direction away from the light incident surface may be formed on the opposite surface of the light guide plate of the present invention in order to make the light distribution on the light output surface uniform. In addition, in a display device, it is preferable that a uniform mountain-shaped light distribution with the highest luminance at the center of the screen is easily visible while improving the uniformity of the light distribution.
As light scattering processing, for example, a dot or uneven shape is made into a gradation pattern in which the area gradually increases as it moves away from the light incident surface, or the same size dot or uneven shape becomes narrower as it moves away from the light source. A gradation pattern that can be used. In this case, examples of the shape of the dots and irregularities include a circle and a quadrangle, and the size can be, for example, about 0.1 to 2.0 mm.

The light guide plate having a concavo-convex structure on the light incident surface as in the present invention is slightly different from that in which the light incident surface is smooth in the direction perpendicular to the light incident surface (light propagation direction). In other words, the amount of light emitted from the light exit surface in the region close to the light entrance surface is larger than that of the light guide plate having a smooth light entrance surface, while the amount of light emitted from the light exit surface in the region far from the light entrance surface is incident. The light surface tends to be smaller than that of a light guide plate having a smooth surface. Therefore, compared to a light guide plate having a smooth light incident surface, the partial light scattering pattern close to the light incident surface of the reflective surface has a shape that is more difficult to scatter than conventional ones (for example, the area of dots and uneven shapes has been further reduced) Or the density is preferably sparse.
However, when the change in the light propagation direction of the amount of light emitted from the light exit surface is too large, there is a limit in the correspondence with the pattern having gradation (for example, when the area is changed, the area is 0% or more and 100% or less). Can only be changed to a range).

FIG. 85 shows the brightness of the light exit surface with the distance from the light entrance surface (the propagation direction of light, the direction of arrow 16 in FIG. 1) on the X axis and the brightness on the Y axis. However, this is the light incident surface of the light guide plate. In the region from the light incident surface to the inside of 16.5 mm, since the light-shielding plate is fixed to fix the distance between the light guide plate and the light source, the luminance is zero. A light guide plate having a smooth light entrance surface (reference), a light guide plate of the present invention (Production Example D-20), and a general diffusion sheet pasted on the light entrance surface of the light guide plate Comparing the luminance of (Production Example D-37), the brightness of Production Examples D-20 and D-37 is higher near the light incident surface than that of the reference, and the production example is farther from the light incident surface. The brightness of D-20 and D-37 is low.
In the light guide plate of the present invention, the brightness at each position on the light exit surface is preferably in the range of 50% or more and 150% or less as compared to the value when the light entrance surface is smooth. More preferably, they are 60% or more and 140% or less, More preferably, they are 70% or more and 130% or less.
Compared with the value when the light incident surface is smooth, the light scattering pattern on the reflective surface can be easily redesigned within this range.

Alternatively, in the light guide plate of the present invention, the light exiting surface and / or the opposing surface is provided near the light incident surface of the light shielding portion shielded by the frame (surface light source device) and / or the light shielding frame (TV receiver device). In the region B, it is possible to provide a light scattering process configured such that the light scattering degree of the partial region directly facing the light source is lower than the light scattering degree of the partial region directly facing the portion between the light sources.
In the region B in the vicinity of the light incident surface of the light shielding portion, a light scattering process is provided so that the light scattering degree of the partial region facing the light source is lower than the light scattering degree of the partial region facing the light source. Thus, in combination with the concavo-convex structure provided on the light incident surface (the light scattering process provided in the vicinity of the light incident surface of such a light exit surface and / or its opposite surface and the concavo-convex structure provided on the light incident surface. Complementing portions where the luminance unevenness reduction effect is mutually lacking), the uniformity of the luminance of the light exit surface is dramatically improved, and the P / G described later can be increased.
The “partial region directly facing the point light source (or the portion between the point light source and the point light source)” refers to the direction parallel to the light incident surface of the light exit surface as the X axis and the direction perpendicular to the light incident surface as the Y axis. Is a partial area having substantially the same X coordinate as the point light source (or the part between the point light source and the point light source), and “the light scattering degree of the partial area directly facing the point light source is the point light source and the point light source. "A lower than (or substantially equal to) the light scattering degree of the partial region directly facing the portion between" means that the partial region directly facing the point light source (substantially the light source) is compared when the partial regions having the same Y coordinate are compared. (Partial region having the same X coordinate) The light scattering degree of the partial region directly facing the portion between the point light source and the point light source (partial region having substantially the same X coordinate as the portion between the point light source and the point light source) It is lower (or approximately equal) than the degree of scattering.

  In the light shielding part shielded by the frame (surface light source device) or the light shielding frame (television receiving device) on the light exit surface and / or the opposing surface, the light scattering degree of the partial area directly facing the point light source is between the point light source and the point light source. A region B in the vicinity of the light incident surface on which light scattering processing is performed so as to be lower than the light scattering degree of the partial region directly facing the portion is a band-like area parallel to the light incident surface in the light shielding portion. However, it is not always necessary to start from the light incident surface side end (Y = 0).

  As a specific aspect of the configuration in which “the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing the portion between the point light source”, for example, a . Light scattering processing is performed in a region other than the partial region directly facing the point light source (light scattering processing is performed on the partial region directly facing the portion between the point light source and the point light source), b. Light scattering processing is applied to almost the entire area near the light incident surface, and the degree of light scattering is lower in the partial areas facing the point light source than in the other partial areas (the area between the point light source and the point light source is positive). For the partial area, the degree of light scattering is higher than that of the other partial areas).

  There is no limitation in light scattering processing, and those generally employed in the field of optical materials can be used. For example, a plurality of diffusive dot patterns made of a reflective or diffusive material may be provided by stacking or printing, or a plurality of three-dimensional dot patterns such as concavo-convex shapes may be formed. There is no limitation in the shape of a dot, For example, circular, a square, etc. are mentioned, The magnitude | size can be about 0.1-2.0 mm, for example.

The light scattering degree is, for example, the concentration of a reflective (diffusible) substance in a diffusive dot made of a reflective (diffusive) material (the higher the density, the higher the light scattering degree), and the shape of the uneven three-dimensional dot. (For example, the higher the height, the higher the light scattering degree), the ratio of the area of the portion where the dots are formed (hereinafter referred to as “dot density”. Note that the dot density changes stepwise within the region. 34 , the dot density of the region is surrounded by vertical bisectors 26a to 26f of line segments connecting the center of the dot 26 and the centers of the adjacent dots A to F as shown in FIG. It can be controlled by adjusting the ratio (%) of the area of the dot 26 to the area of the square 262, and the higher the dot density, the higher the light scattering degree. Dot density, for example, changes the area of each dot with a constant number of dots per unit area, or conversely changes the number of dots per unit area with a constant area of each dot (dot pitch) It is possible to make adjustments by changing both of them.

In the present invention, a region A (at least a non-light-shielding portion) that covers at least a non-light-shielding portion that is not shielded by the frame (surface light source device) or the light-shielding frame (television receiver) on the light exit surface and / or the opposing surface of the light guide plate. Light-scattering processing can also be performed. At this time, the range of the region A is preferably set as appropriate so that a region C described later exists between the region A and the region B.
In the region A, at least in the non-light-shielding part, the light scattering degree of the partial area directly facing the point light source and the light scattering degree of the partial area directly facing the part between the point light source and the point light source are substantially equal. It is preferable.

The region C sandwiched between the region A and the region B is preferably a band-like region parallel to the light incident surface, in which case the width of the region C is preferably 0.2 mm or more, more preferably 0.5 mm or more. And most preferably 1 mm or more. Further, the upper limit of the width of the region C is preferably 3.0 mm or less, more preferably 2.0 mm or less, and most preferably 1.5 mm or less.
In the region C, it is preferable that light scattering processing is not provided at least in a partial region directly facing the portion between the point light source and the light source processing may not be provided at all in the region C. .

  18 and 19 show specific examples of the light scattering processing applied to the light exit surface and / or the facing surface. Further, in the example of FIG. 18, in the region B near the light incident surface, the light scattering process is not provided in the partial region directly facing the point light source, thereby facing the point light source in the region near the light incident surface. The light scattering degree of the partial area is set to be lower than the light scattering degree of the partial area directly facing the portion between the point light source and the point light source. In the example of FIG. 19, in the region B near the light incident surface, the area of each dot in the partial region facing the point light source is small, and in the portion between the point light source and the point light source near the light incident surface. By increasing the area of each dot of the facing partial area, the light scattering degree of the partial area directly facing the point light source in the area near the light incident surface is the light of the partial area facing the part between the point light source and the point light source. It is set to be lower than the scattering degree.

FIG. 35 shows a cross-sectional view of an example of the surface light source device and the television receiver of the present invention. The light emitting area of the surface light source device is defined (restricted) by a frame (BL frame), and the display area of the television receiving device is defined (restricted) by a light shielding frame (black matrix).

FIG. 36 shows another specific example of the light scattering processing of the light exit surface and / or the opposing surface in the present invention.
In the example of FIG. 36, a partial region directly facing the point light source is located in a region B (a strip-shaped area parallel to the light incident surface) in the vicinity of the light incident surface of the light shielding portion (that is, outside the display area or the light emitting area). Light scattering processing is applied so that the light scattering degree is lower than the light scattering degree of the partial area directly facing the part between the point light source and the light scattering of the partial area directly facing the point light source. In the light scattering processing that is configured so that the degree of light scattering is lower than the light scattering degree of the partial region that directly faces the portion between the point light source and each of the partial regions that face the point light source in the region near the light incident surface By reducing the area of the dots, and by increasing the area of each dot in the partial area facing the part between the point light source and the point light source in the area near the light incident surface, the point light source in the area near the light incident surface Light scattering degree of the partial region facing directly It is set to be lower than the degree of light scattering of directly opposite partial region a portion between the point light source and a point light source.
In the non-light-shielding part (that is, the display area or the light emitting area), the light scattering degree of the partial area directly facing the point light source is substantially equal to the light scattering degree of the partial area directly facing the part between the point light source and the point light source. Is light-scattered. Specifically, when the light scattering degree is controlled by the dot density, the dot density ρ1 in the lowest dot density region and the highest dot density among the regions having the same distance from the light incident surface (regions having the same Y coordinate). The ratio (ρ2 / ρ1) of the dot density ρ2 in the high region is preferably ρ2 / ρ1 ≦ 1.2, more preferably ρ2 / ρ1 ≦ 1.1, and ρ2 / ρ1 = 1. Is most preferred.
A light scattering process configured such that the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing the part between the point light source and the light shielding part / non-light shielding part; The light scattering degree of the partial area directly facing the point light source is configured to be lower than the light scattering degree of the partial area directly facing the part between the point light source and the point light source. By placing the light scattering process in the light shielding portion), it is possible to prevent the luminance unevenness of the light emitting surface / display surface from being viewed not only from the front but also from an oblique direction.

FIG. 37 shows another specific example of the light scattering processing of the light exit surface and / or the opposing surface in the present invention.
In the example of FIG. 37 , a region B (light incident surface) in the vicinity of the light incident surface that is set to be approximately several mm outside (light incident surface side) from the boundary with the non-light-shielded portion (display area or light emitting area). In a strip-like area parallel to the point light source), dots are formed at a density that is twice to 20 times higher than the dot density of the non-light-shielding part only in the partial region directly facing the part between the point light source and the point light source. The density is preferably 5 to 15 times, and most preferably about 10 times.
In this way, by performing light scattering processing only on the partial region directly facing the portion between the point light source and the point light source in the region B in the vicinity of the light incident surface of the light-shielding portion, a pseudo between the point light source and the point light source is obtained. By generating a light source and overlapping this with an image of an actual light source, it is possible to reduce luminance unevenness derived from a point light source.
Further, in the example of FIG. 37 , the light scattering degree and the point light source of the partial area directly facing the point light source in the non-light-shielded part and the surrounding area (boundary area in the vicinity of the boundary between the light-shielded part and the non-light-shielded part). The region A is formed by performing light scattering processing so that the light scattering degree of the partial region facing the portion between the point light source and the point light source becomes substantially equal.
And between the area | region A and the area | region B, the area | region C (band-like area | region parallel to a light-incidence surface) in which the light-scattering process is not provided exists.

The region B preferably starts from the outside of 1 mm or more from the boundary between the light shielding part and the non-light shielding part. By doing so, the above-described pseudo light source can be prevented from being visually recognized by the user when the surface light source device or the television receiver is used.
In addition, the light scattering processing (light scattering processing to be a pseudo light source) applied to the partial region facing the portion between the point light source and the point light source in the region B near the light incident surface is the center (light source and light source). It is preferable to apply a gradation in which the degree of light scattering increases toward the middle). By doing so, the light reaching from the left and right point light sources is strongly scattered toward the central part in the partial area facing the part between the point light source and the point light source, and a dark part is generated in the center of the pseudo light source scattering processing part. It is possible to provide a natural pseudo light source unit. In addition, the density distribution of the gradation is normal to the point light source with respect to the partial region (the central region in the direction parallel to the light-scattering light incident surface that becomes a pseudo light source) that is directly opposite the point light source. The density in the vicinity of the corresponding partial area (both ends in the direction parallel to the light incident surface of the light scattering process as a pseudo light source) is preferably a gradation set in a range of about 5% to 80%, preferably 10% -70% is more suitable, 20%-50% is still more suitable, and 30%-40% is the most suitable.

When the light scattering degree is controlled by the dot density, the dot density ρ1 of the lowest dot density among the partial areas directly facing the point light source in the area B near the light incident surface and the point light source in the area B near the light incident surface The dot density so that the ratio (ρ2 / ρ1) of the dot density ρ2 of the region having the highest dot density among the partial regions directly facing the portion between the point light sources satisfies the following relationship: It is preferable to adjust ρ1 and ρ2.
2.9 ≦ 1.4 × (P / G) −ρ2 / ρ1 ≦ 3.1
Here, the dot density ρ (%) of a certain area is a specific dot (26) included in the area.
) And a perpendicular bisector (26a-f) of a line segment connecting the center point of the dot (A to F) adjacent to the specific dot so as to surround the specific dot The area ratio of the polygon (263) that can be generated is expressed as a percentage with the area of the specific dot (26) as the numerator (see FIG. 34 ).

44 to 53 show still another specific example of the light scattering processing applied to the light exit surface and / or the facing surface.
Further, in the table below, these light scattering processing and the light scattering processing of FIG. 41 employed in Production Example A-11 described later, and the optical sheet (diffusion sheet (DS)) laminated on the LED array pitch and the light guide plate , A preferred combination of prism sheet (Prism) and reflective polarizing sheet (DBEF).
In addition, when there is no description in the table | surface, it is normal to the light-incidence surface (a several recessed part (convex part) which has an anisotropic shape with an opening (bottom surface) long in a direction perpendicular | vertical to an output surface) of a light-guide plate. When a light beam is incident from the direction, the diffusion angle in a direction parallel to the light exit surface (in the table, indicated as “surface direction”) is preferably 50 ° to 100 °, and preferably 60 ° to 85 °. More preferably, it is 70 ° or more and 80 ° or less.
In addition, unless otherwise specified in the table, the normal to the light incident surface of the light guide plate (a plurality of concave portions (convex portions) having an opening (bottom surface) having a long anisotropic shape in a direction perpendicular to the light output surface) When a light beam is incident from the direction, the diffusion angle in the direction perpendicular to the light exit surface (in the table, “displayed as the thickness direction”) is preferably 20 ° or less, more preferably 1 ° or less. 0.5 ° or less is most preferable.

The effect of the pseudo light source between the light sources formed by the light scattering processing shown in FIG. 52 will be described.
The light scattering process of FIG. 52 is performed on the opposing surface of a light guide plate (material: polymethyl methacrylate, thickness: 3.0 mm, width: 409 mm, length: 721 mm), and is composed of diffusion beads and a binder. Circular diffusive dots with a diameter of 0.8 mm to 1.3 mm are arranged in a staggered pattern (in a triangular lattice pattern), 2.5 to 3.5 mm from the light incident surface side end (light-shielding portion, region near the light incident surface) In the partial area directly facing between the light sources of B), 4.5 to 6 mm from the end on the light incident surface side (shielding part (boundary area), area A) so that ρ = 50 to 100%. In FIG. 5, ρ = 10% is provided so that ρ = 9% after 6 mm from the light incident surface side end portion (non-light-shielding portion, region A), and in other regions. Are not provided with diffusive dots.
A polyethylene terephthalate film having a groove structure having the surface profile shown in FIG. 25 and having an average thickness of 125 μm is pasted on the light incident surface of the light guide plate subjected to the light scattering processing of FIG. 52 using a transparent double-sided adhesive sheet. The LEDs (light emitting surface size 5.0 mm (width direction) × 3.0 mm (thickness direction), 42 LEDs) were arranged so that the array pitch P was 16.0 mm along the light incident surface.
On top of this, from the light guide plate side, a diffusion sheet (DS) / prism sheet (having a groove structure having a ridge line parallel to the light incident surface on which the LED is arranged on the surface) / DBEF are laminated in this order, Furthermore, a surface light source device is manufactured by disposing a frame having an opening of 395 mm × 700 mm in a size that sufficiently covers the light guide plate and the LED so as to face the light exit surface side of the light guide plate. When evaluated, the area of the pseudo light source formed between the light sources by light scattering processing is 2.5 to 3.5 mm even in the range of 1.5 to 2.5 mm from the light incident surface side end. Compared with the light guide plate in which the diffusive dots were formed with the density ρ similar to that in the range, the hot spot was suppressed more effectively, that is, it worked more strongly as a pseudo light source.
This indicates that the light scattering processing at the light incident surface side end 1.5 mm to 2.5 mm does not contribute much to the suppression of hot spots, and rather the light incident surface side end 2.5 mm to 3.5 mm. This suggests that reducing the amount of light that arrives reduces the effect of a pseudo-light source.
Also in the light scattering processing shown in FIG . 45 to FIG. 51 and FIG. 41 , the light incident surface edge portion is between 2.5 mm to 3.5 mm (corresponding to one line of dot lines in the size of the diffusive dots applied thereto) The above-described effect can be obtained by replacing only the pattern of the part with the pattern between 2.5 mm and 3.5 mm in FIG .
In this case, since the dot lines are as simple as one line, the design is relatively easy and the development speed is improved. And it is also preferable to respond | correspond by forming only this dot 1 line part by the additional printing of another process, or bonding an additional dot seal to a back surface.

In order to achieve further uniformity of the light distribution on the light exit surface, the light scattering processing in the region near the light entrance surface and the light scattering processing in other regions are further performed in a direction away from the light entrance surface. A gradation that increases the degree of scattering (for example, a gradation in which the dot area increases as the distance from the light incident surface increases, or a gradation in which the pitch of the same size dot decreases as the distance from the light source decreases) can also be provided. .
Further, in the case of a surface light source device for a display device, it is preferable that a uniform mountain-shaped light distribution with the highest luminance at the center of the screen is easy to visually recognize while improving the uniformity of the light output distribution. The light scattering processing provided on the light exit surface and / or the opposing surface may be further configured to increase the light scattering degree of the central portion.

The light scattering process in the vicinity of the light incident surface described above may be provided on either the light exit surface or the opposing surface, or may be provided on both. However, when the light scattering process is easily visible, it is preferable that the light scattering process is provided only on the facing surface.
Moreover, you may provide the groove | channel structure substantially parallel to the normal line direction of the light-incidence surface mentioned above in the direction which does not perform light-scattering processing among a light emission surface and / or an opposing surface. Providing such a groove structure on the light exit surface and / or the opposing surface can suppress the spread of light emitted from the light exit surface, so that the light guide plate can be made suitable for local dimming.

As another aspect, the light scattering degree of the partial region directly facing the point light source in the region near the light incident surface on the light exit surface and / or the opposing surface of the light guide plate of the present invention is between the point light source and the point light source. It is also possible to provide a light scattering process configured so as to be lower than the light scattering degree of the partial region directly facing the portion.
By providing such light scattering processing on the light exit surface and / or the opposing surface, in combination with the concavo-convex structure provided on the light incident surface (such light scattering processing and the concavo-convex structure provided on the light incident surface are Complementing portions where the luminance unevenness reduction effect is mutually lacking), the uniformity of the luminance of the light exit surface is dramatically improved, and the P / G described later can be increased.
The “partial region directly facing the point light source (or the portion between the point light source and the point light source)” refers to the direction parallel to the light incident surface of the light exit surface as the X axis and the direction perpendicular to the light incident surface as the Y axis. Is a portion of a region having substantially the same Y coordinate, and a partial region having substantially the same X coordinate as a point light source (or a portion between the point light source and the point light source).

  Regarding a region where light scattering processing is performed on the light exit surface and / or the opposing surface (hereinafter also referred to as “light scattering processing region”), “in the region near the light incident surface, light in a partial region directly facing the point light source There is no limitation as long as the condition that the scattering degree is lower than the light scattering degree of the partial region directly facing the portion between the point light source and the point light source is satisfied, not necessarily the light incident surface side It is not necessary that the light scattering processing region starts from the end (Y = 0). For example, when the surface light source device has a frame (a frame having an opening that defines a light emitting area) and the outer peripheral portion of the light emitting surface is covered with this frame, only the central portion of the light emitting surface of the light guide plate emits light. When used as an area, the light scattering processing starts from a position where the overlap between the light scattering processing region and the frame on the light incident surface side is about 10 mm or less (more preferably about 6 mm or less). It is preferable from the viewpoint of in-plane (in the light emitting area) average luminance. However, from the viewpoint of preventing the start line of light scattering processing from being visible when used in a display device or the like, the overlap should be present to some extent, preferably 1 mm or more, more preferably about 2 mm. preferable.

  Specific aspect of configuration in which “in the region near the light incident surface, the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing the portion between the point light source” For example, a. Performing light scattering processing in a region near the light incident surface other than a partial region facing the point light source; b. Performing light scattering processing only on a partial region directly facing a portion between the point light source in the region near the light incident surface; c. Apply light scattering processing to substantially the entire area of the light exit surface and / or the opposing surface so that the light scattering degree of the partial region directly facing the point light source in the region near the light incident surface is lower than the other partial regions, and / or Alternatively, in a region near the light incident surface, a light scattering degree of a partial region directly facing a portion between the point light source and the point light source may be higher than that of other partial regions.

  There is no limitation in light scattering processing, and those generally employed in the field of optical materials can be used. For example, a pattern of a plurality of diffusive dots (hereinafter also simply referred to as “dots”) made of a reflective or diffusive material is provided by stacking or printing, or a pattern of a plurality of three-dimensional dots such as an uneven shape is formed. Forming. There is no limitation in the shape of a dot, For example, circular, a square, etc. are mentioned, The magnitude | size can be about 0.1-2.0 mm, for example.

  The light scattering degree is, for example, the concentration of a reflective (diffusible) substance in a diffusive dot made of a reflective (diffusive) material (the higher the density, the higher the light scattering degree), and the shape of the uneven three-dimensional dot. (For example, the higher the height, the higher the light scattering degree), the proportion of the area where the dots are formed (hereinafter referred to as “dot density”) (the higher the dot density, the higher the light scattering degree) It can be controlled by adjusting). Dot density, for example, changes the area of each dot with a constant number of dots per unit area, or conversely changes the number of dots per unit area with a constant area of each dot (dot pitch) It is possible to make adjustments by changing both of them.

76 and 77 show specific examples of light scattering processing. Further, in the example of FIG. 76 , by not providing dots in the partial region that faces the point light source in the region near the light incident surface, the light in the partial region that faces the point light source in the region near the light incident surface. The scattering degree is set to be lower than the light scattering degree of the partial region directly facing the portion between the point light source and the point light source. In the example of FIG. 77, the area of each dot in the partial area that faces the point light source is small in the area near the light incident surface, and the area between the point light source and the point light source in the area near the light incident surface. By increasing the area of each dot of the facing partial area, the light scattering degree of the partial area directly facing the point light source in the area near the light incident surface is the light of the partial area facing the part between the point light source and the point light source. It is set to be lower than the scattering degree.

When the light scattering degree is controlled by the dot density, the dot light source ρ1 and the point light source in the region near the light incident surface and the dot density ρ1 of the region having the lowest dot density among the partial regions directly facing the point light source in the region near the light incident surface. The dot density ρ1, so that the ratio (ρ2 / ρ1) of the dot density ρ2 of the region with the highest dot density in the partial region directly facing the portion between the two and P / G described later satisfies the following relationship: It is preferable to adjust ρ2.
2.9 ≦ 1.4 × (P / G) −ρ2 / ρ1 ≦ 3.1
However, when the dot density in each partial area changes stepwise, the dot density of a partial area is the center point of the specific dot (26) included in the partial area and the specific point. Of a polygon (263) formed by a perpendicular bisector (26a-f) of a line segment connecting the center point of the dots (A to F) adjacent to the particular dot, and surrounding the specific dot With the area as the denominator, the area ratio with the area of the specific dot (26) as the numerator is expressed as a percentage (see FIG. 34 ).

In order to achieve further uniformity of the light emission distribution on the light exit surface, the light scattering processing further includes a gradation in which the light scattering degree increases toward the direction away from the light entrance surface (for example, dots as the distance from the light entrance surface increases). A gradation that increases the area, and a gradation in which dots having the same area are arranged so that the pitch becomes narrower as they move away from the light incident surface can also be given.
Further, in the case of a surface light source device for a display device, it is preferable that a uniform mountain-shaped light distribution with the highest luminance at the center of the screen is easy to visually recognize while improving the uniformity of the light output distribution. The light scattering processing provided on the light exit surface and / or the opposing surface may be further configured to increase the light scattering degree of the central portion.

The light scattering process described above may be provided on either the light exit surface or the opposing surface, or may be provided on both. However, when the light scattering process is easily visible, it is preferable that the light scattering process is provided only on the facing surface.
Moreover, you may provide the groove | channel structure substantially parallel to the normal line direction of the light-incidence surface mentioned above in the direction which does not perform light-scattering processing among a light emission surface and / or an opposing surface. Providing such a groove structure on the light exit surface and / or the opposing surface can suppress the spread of light emitted from the light exit surface, so that the light guide plate can be made suitable for local dimming.

As yet another aspect, the light exit surface and / or the opposing surface of the light guide plate of the present invention has a light entrance surface in a light shielding portion shielded by a frame (surface light source device) and / or a light shielding frame (display device). A light scattering process configured so that the light scattering degree of the partial area directly facing the point light source is lower than the light scattering degree of the partial area directly facing the part between the point light sources is provided in a nearby area. You can also.
The light scattering processing is performed so that the light scattering degree of the partial region facing the point light source is lower than the light scattering degree of the partial region facing the point light source. By providing it in a region in the vicinity of the light incident surface of the surface, in combination with the concavo-convex structure provided on the light incident surface (the light scattering degree of the partial region directly facing the point light source on such a light emitting surface and / or its opposite surface) The light scattering processing configured to be lower than the light scattering degree of the partial region directly facing between the point light source and the point light source and the uneven structure provided on the light incident surface are insufficient in reducing the uneven brightness. Complementing the portions), the uniformity of the brightness of the light exit surface is dramatically improved, and the P / G described later can be increased.
The “partial region directly facing the point light source (or the portion between the point light source and the point light source)” refers to the direction parallel to the light incident surface of the light exit surface as the X axis and the direction perpendicular to the light incident surface as the Y axis. Is a portion of an area having substantially the same Y coordinate and having an X coordinate substantially the same as that of the point light source (or the portion between the point light source and the point light source). The light scattering degree of the partial region is lower than (or substantially equal to) the light scattering degree of the partial region directly facing the portion between the point light source and the partial region facing the point light source (substantially the point light source) (Partial region having the same X coordinate) The light scattering degree of the partial region directly facing the portion between the point light source and the point light source (partial region having substantially the same X coordinate as the portion between the point light source and the point light source) It is lower (or approximately equal) than the degree of scattering.

The light scattering degree of the partial region directly facing the point light source applied in the light shielding part shielded by the frame (surface light source device) or the light shielding frame (display device) on the light emitting surface and / or the opposing surface is a point light source and a point light source. The light scattering processing that is configured to be lower than the light scattering degree of the partial region that directly faces the portion in between may be applied to at least a part of the region near the light incident surface of the light shielding portion. It is applied in a band-shaped area parallel to the light incident surface of the portion or in a band-shaped area parallel to the light incident surface 1 mm or more (light incident surface side) outside the boundary with the non-light-shielding portion. It is preferable.
Further, this light scattering processing does not necessarily have to start from the light incident surface side end (Y = 0).

The light scattering degree of the partial area directly facing the point light source of the light-shielding part of the light exit surface and / or the opposing surface is configured to be lower than the light scattering degree of the partial area directly facing the part between the point light source and the point light source. A region other than a region subjected to light scattering processing (for example, a boundary area sandwiched between a non-light-shielding portion and the vicinity of a light incident surface (located near the boundary between the light-shielding portion and the non-light-shielding portion), or a light guide plate (Area parallel to the side perpendicular to the light incident surface) may or may not be provided with light scattering processing, but the portion between the point light source and the point light source on the light exit surface (opposite surface) As for the partial region directly facing the surface, it is preferable that the light scattering degree does not change suddenly in the Y-axis direction through the surface (through the light-shielding part and the non-light-shielding part) (the light scattering degree is continuous). So that the degree of light scattering does not change rapidly in the Y-axis direction. It is preferable to provide an appropriate light scattering process.
Further, in the boundary area described above, the light scattering degree of the partial area directly facing the point light source and the light scattering degree of the partial area directly facing the part between the point light source and the point light source may be substantially equal. preferable.

  As a specific aspect of the configuration in which the “light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the region facing the part between the point light source and the point light source”, for example, a. Light scattering processing is performed in a region other than the partial region directly facing the point light source (light scattering processing is performed on the partial region directly facing the portion between the point light source and the point light source), b. Light scattering is applied to almost the entire area in the area near the light entrance surface, and the degree of light scattering is lower in the partial area facing the point light source than in other partial areas (in the part between the point light source and the point light source). For a partial region that faces directly, the degree of light scattering is higher than that of other partial regions).

  There is no limitation in light scattering processing, and those generally employed in the field of optical materials can be used. For example, a pattern of a plurality of diffusive dots (hereinafter also simply referred to as “dots”) made of a reflective or diffusive material is provided by stacking or printing, or a pattern of a plurality of three-dimensional dots such as an uneven shape is formed. Forming. There is no limitation in the shape of a dot, For example, circular, a square, etc. are mentioned, The magnitude | size can be about 0.1-2.0 mm, for example.

The light scattering degree is, for example, the concentration of a reflective (diffusible) substance in a diffusive dot made of a reflective (diffusive) material (the higher the density, the higher the light scattering degree), and the shape of the uneven three-dimensional dot. (For example, the higher the height, the higher the light scattering degree), the ratio of the area of the portion where the dots are formed (hereinafter referred to as “dot density”. Note that the dot density changes stepwise within the region. 34 , the dot density of the region is surrounded by vertical bisectors 26a to 26f of line segments connecting the center of the dot 26 and the centers of the adjacent dots A to F as shown in FIG. It can be controlled by adjusting the ratio (%) of the area of the dot 26 to the area of the square 262, and the higher the dot density, the higher the light scattering degree. Dot density, for example, changes the area of each dot with a constant number of dots per unit area, or conversely changes the number of dots per unit area with a constant area of each dot (dot pitch) It is possible to make adjustments by changing both of them.

  In this aspect, in a region composed of a non-light-shielding portion that is not shielded by the frame (surface light source device) or the light-shielding frame (display device) on the light exit surface and / or the opposing surface of the light guide plate, the partial region directly facing the point light source It is preferable that the light scattering degree of the light source is substantially equal to the light scattering degree of the partial region directly facing the portion between the point light source and the point light source. The non-light-shielding part may or may not be provided with light scattering processing, but for the partial region facing the part between the point light source and the point light source on the light exit surface (opposing surface), through the surface, Since it is preferable that the light scattering degree does not change abruptly in the Y-axis direction (since it is preferable that the light scattering degree is continuous), light scattering is appropriately performed so that the light scattering degree does not change rapidly in the Y-axis direction. It is preferable to provide processing.

76 and 77 show specific examples of the light scattering processing performed on the light exit surface and / or the opposite surface. In the example of FIG. 76, the partial region that faces the point light source in the region near the light incident surface is provided by not providing light scattering processing in the partial region that faces the point light source in the region near the light incident surface. The light scattering degree is lower than the light scattering degree of the partial region directly facing the portion between the point light source and the point light source. In the example of FIG. 77, the area of each dot in the partial area that faces the point light source is small in the area near the light incident surface, and the area between the point light source and the point light source in the area near the light incident surface. By increasing the area of each dot of the facing partial area, the light scattering degree of the partial area directly facing the point light source in the area near the light incident surface is the light of the partial area facing the part between the point light source and the point light source. It is set to be lower than the scattering degree.

FIG. 35 shows a cross-sectional view of an example of the surface light source device and the display device of the present invention. The light emitting area of the surface light source device is defined (limited) by a frame (BL frame), and the display area of the display device is defined (limited) by a light shielding frame (black matrix).

FIG. 105 shows a light scattering process configured such that the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing between the point light source and the light shielding portion / non-shielding portion. A specific example of the positional relationship with the light shielding portion will be shown.
In the example of FIG. 105 , the light scattering degree of the partial area directly facing the point light source in the light-shielding part (that is, outside the display area or the light emitting area) parallel to the light incident surface is the point light source and the point light source. Light scattering processing is performed so that the light scattering degree of the partial area facing the part is lower than the point light source, and the light scattering degree of the partial area facing the point light source is between the point light source and the point light source. In the light scattering processing configured to be lower than the light scattering degree of the partial area directly facing the part, the area of each dot in the partial area directly facing the point light source is reduced in the area near the light incident surface. By increasing the area of each dot in the partial area that faces the portion between the point light source and the point light source in the area near the light surface, the light scattering degree of the partial area that faces the point light source in the area near the light incident surface is increased. Between point light source and point light source It is set to be lower than the degree of light scattering of the positive against partial zones within.
In the non-light-shielding part (that is, the display area or the light emitting area), the light scattering degree of the partial area directly facing the point light source is substantially equal to the light scattering degree of the partial area directly facing the part between the point light source and the point light source. Is light-scattered. Specifically, when the light scattering degree is controlled by the dot density, the dot density ρ1 of the partial area with the lowest dot density and the highest dot density among the partial areas belonging to the same area (partial areas having the same Y coordinate). The ratio (ρ2 / ρ1) of the dot density ρ2 of the partial region is preferably ρ2 / ρ1 ≦ 1.2, more preferably ρ2 / ρ1 ≦ 1.1, and ρ2 / ρ1 = 1. Is most preferred.
A light scattering process configured such that the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing the part between the point light source and the light shielding part / non-light shielding part; Is configured as described above (that is, the light scattering degree of the partial area directly facing the point light source is lower than the light scattering degree of the partial area directly facing the part between the point light source and the point light source) By placing the light scattering process in the light shielding portion), it is possible to prevent the luminance unevenness of the light emitting surface / display surface from being viewed not only from the front but also from the oblique direction.

In FIG. 106 , the light scattering processing configured such that the light scattering degree of the partial region directly facing the point light source is lower than the light scattering degree of the partial region directly facing the portion between the point light source and the point light source; Another specific example of the positional relationship between the light shielding part / non-light shielding part will be shown.
In the example of FIG. 106 , similarly to FIG. 76 , light scattering processing is performed only on (part of) a partial region that is directly opposite to the portion between the point light source in the region near the light incident surface in the light shielding portion. In addition, the light scattering process is not applied to the partial region directly facing the point light source.
Specifically, it is parallel to the light incident surface set outside (light incident surface side) by 0 mm or more (for example, about several mm) from the boundary between the light shielding portion and the non-light shielding portion (display area or light emitting area). Dots are formed at a density two to ten times higher than the dot density of the non-light-shielding portion only in the partial area directly facing the portion between the point light sources in the band-like area B.
In this way, by performing light scattering processing only on the partial region directly facing the portion between the point light source and the point light source of the light shielding portion, a pseudo light source is generated between the point light source and the point light source. By overlapping the image of the point light source, unevenness derived from the point light source can be reduced.
In the example of FIG. 106 , in the light shielding portion, the area near the boundary with the non-light shielding portion (boundary area) includes the light scattering degree of the partial region directly facing the point light source and between the point light source and the point light source. Light scattering processing is performed so that the light scattering degree of the partial region facing the portion is substantially equal, and the area A is formed together with the non-light-shielding portion.

The area B is preferably outside by 1 mm or more from the boundary between the light shielding part and the non-light shielding part. By doing so, the above-described pseudo light source can be prevented from being visually recognized by the user when the surface light source device or the display device is used.
In addition, the light scattering processing portion (light scattering processing applied to the partial area directly facing the portion between the point light source and the point light source in the area near the light incident surface) serving as a pseudo light source is the center (point It is preferable to apply a gradation that increases the degree of light scattering toward the middle of the light source and the point light source. By doing so, the light arriving from the left and right point light sources strongly scatters toward the center part between the point light source and the point light source, and the natural pseudo-light source is not generated in the center of the pseudo light source scattering processed part. A light source unit can be provided.

In the case of controlling the light scattering degree by the dot density, the dot density ρ1 of the partial area having the lowest dot density among the partial areas facing the point light source in the area near the light incident surface and the point light source and the point in the area near the light incident surface The dot density so that the ratio (ρ2 / ρ1) of the dot density ρ2 of the partial region having the highest dot density among the partial regions directly facing the portion between the light sources satisfies the following relationship: It is preferable to adjust ρ1 and ρ2.
2.9 ≦ 1.4 × (P / G) −ρ2 / ρ1 ≦ 3.1
However, when the dot density in each partial area changes stepwise, the dot density of a partial area is the center point of the specific dot (26) included in the partial area and the specific point. Of a polygon (263) formed by a perpendicular bisector (26a-f) of a line segment connecting the center point of the dots (A to F) adjacent to the particular dot, and surrounding the specific dot With the area as the denominator, the area ratio with the area of the specific dot (26) as the numerator is expressed as a percentage (see FIG. 34 ).

In order to achieve further uniformity of the light distribution on the light exit surface, light scattering processing near the light entrance surface and other light scattering treatments that are appropriately performed are further scattered in the direction away from the light entrance surface. A gradation that increases the degree (for example, a gradation in which the dot area increases as the distance from the light incident surface increases, or a gradation in which dots having the same area are arranged so that the pitch decreases as the distance from the light incident surface) is also given. it can.
Further, in the case of a surface light source device for a display device, it is preferable that a uniform mountain-shaped light distribution with the highest luminance at the center of the screen is easy to visually recognize while improving the uniformity of the light output distribution. The light scattering processing provided on the light exit surface and / or the opposing surface may be further configured to increase the light scattering degree of the central portion.

The light scattering process in the vicinity of the light incident surface described above may be provided on either the light exit surface or the opposing surface, or may be provided on both. However, when the light scattering process is easily visible, it is preferable that the light scattering process is provided only on the facing surface.
Moreover, you may provide the groove | channel structure substantially parallel to the normal line direction of the light-incidence surface mentioned above in the direction which does not perform light-scattering processing among a light emission surface and / or an opposing surface. Providing such a groove structure on the light exit surface and / or the opposing surface can suppress the spread of light emitted from the light exit surface, so that the light guide plate can be made suitable for local dimming.

Next, the surface light source device of the present invention will be described.
FIG. 9 shows a schematic diagram of an example of the surface light source device of the present invention.
The surface light source device 9 of the present invention includes a light guide plate 91, a plurality of point light sources 92 disposed in the vicinity of the light incident surface 93 of the light guide plate, and a frame disposed so as to face the light exit surface of the light guide plate 91 ( (Not shown).

  Although there is no limitation in a point light source, it is preferable to use LED (light emitting diode). Since the LED can obtain high-luminance light with low power consumption and emit light brightly even when the temperature is low, it is possible to provide a surface light source device and a lighting device having sufficient illuminance immediately after lighting. There is no limitation on the type of LED, for example, a one-chip type pseudo white LED that excites green and red phosphors by a blue LED, a multi-chip type that combines white / red / green / blue LEDs to produce white light, and the near ultraviolet One-chip type pseudo white LED that combines an LED and a red / green / blue phosphor may be used.

  FIG. 10 shows a schematic diagram of an example of a box-type LED 10 that can be used in the present invention. The outer shape of the LED and the size of the light emitting surface are not limited, but the outer shape is about 5.6 mm (width) × 3.0 mm (height) × 1.0 mm (thickness), and the lateral width 102 of the light emitting surface 101 is 5 mm. The following are commonly used:

  The distance between the light emitting surface of the point light source and the light incident surface of the light guide plate is preferably 0.1 mm or more and 1.5 mm or less. More preferably, it is 0.3 mm or more and 1.0 mm or less. When the distance between the light guide plate and the light emitting surface is increased, the amount of light incident on the light guide plate is reduced by the inverse square law, and as a result, the total amount of light emitted from the light output surface is also reduced. Therefore, the distance between the light emitting surface of the point light source and the light incident surface of the light guide plate is preferably short. On the other hand, since heat is generated around the point light source and the light guide plate expands, it is necessary to leave a gap that can withstand the expansion.

  Although there is no limitation on the arrangement method of the point light source, it is arranged on the straight line along the light incident surface of the light guide plate (parallel to the light emitting surface) at regular intervals (“equal interval” includes an error of ± 10%). It is preferable to do. In this case, the arrangement pitch P of the point light sources is generally, for example, about the width (outer shape) of the point light source to about 200 mm. From the viewpoint of preventing uneven brightness, the point light sources are preferably arranged as densely as possible, and in view of mounting restrictions on the substrate, it is preferable that the distance is increased to some extent. The arrangement pitch of the point light sources is preferably 5 mm to 200 mm, more preferably 10 to 100 mm.

  However, in the surface light source device of the present invention, the light guide plate with reduced luminance unevenness in the vicinity of the light incident surface on the light exit surface is used as the light guide plate, so even if the arrangement pitch of the point light sources is somewhat large, No light exit surface can be realized. Specifically, for example, if it is about 20 mm to 50 mm, 30 mm to 50 mm, or 40 mm to 50 mm, the luminance unevenness can be suppressed within an allowable range.

In the above, description has been made on the assumption that the LED is a Lambertian LED as shown in FIG . A Lambertian LED is an LED having a light emitting surface that is substantially flat and has a layer in which a highly diffusible phosphor is dispersed inside, and emits light with a light distribution close to the Lambert model in all directions. Is a feature.

Here, the effect of the concavo-convex structure provided on the light incident surface of the light guide plate of the present invention is not simply that the light is spread by the concavo-convex structure, but the light originally emitted from the LED in a wide direction is from the light incident surface. When entering the inside of the light guide plate, the spread is prevented from being suppressed by refraction as shown in FIG. 167, and it is also possible to make it enter with a wide angle as shown in FIG .

Therefore, if a high diffusion LED having a lens as shown in FIG. 165 is used as a point light source, the angle distribution of the light emission intensity of the LED can be as shown in FIG. Can distribute light. As shown in FIG. 168 , the light in the wide angle direction can enter the light guide plate at a wide angle through the uneven surface.

Therefore, in the present invention, as a point light source, an LED (high diffusion LED) having a lens in which a portion facing the center of the LED in a cross section cut parallel to the length direction of the light incident surface is recessed on the surface. It is also preferable to use it.
By combining the uneven structure on the light incident surface of the light guide plate and the above-described high diffusion LED (for example, FIG. 169 ), the hot spot suppressing ability greatly exceeds the effect obtained by the combination of the Lambertian LED and the uneven structure. As a result, it contributes to the reduction of LEDs and the narrowing of frames. Further, the effect by the combination of the light scattering process light emitting surface and / or the opposing surface is represented by such Figure 41 can be further increased.

The surface light source device of the present invention further includes a frame that defines a light emitting area (irradiation area) of the surface light source device, which is disposed to face the light exit surface of the light guide plate. The frame is made of a material that does not transmit the light from the point light source, and the region corresponding to the light emitting area is made of, for example, an opening.
The frame may further include a cover portion that can accommodate the light guide plate and the point light source therein, and the surface light source device may have a clean appearance by concealing the light source and the like therein. it can.

The frame is configured such that the light emitting area starts from the inside of the light incident surface of the light guide plate.
Furthermore, in the case where the light scattering surface as described above is applied to the light exit surface and / or the facing surface of the light guide plate, the light emitting area is near the light entrance surface of the light exit surface and / or the facing surface of the light guide plate, The light scattering degree of the partial region that faces the point light source is lower than the light scattering processing that is configured so that the light scattering degree of the partial region that faces the part between the point light source and the point light source is lower. It is preferable to be configured to start from the inside.
In other words, the region where the light scattering surface of the light guide plate and / or the opposite surface is subjected to the light scattering process is outside of the range facing the opening of the frame on at least one light incident surface side, preferably 0 to 0. 10 mm (excluding 0 mm), more preferably 1 to 6 mm, still more preferably 1 to 4 mm, and particularly preferably 2 mm outside. If it does in this way, while there is no possibility that the start line of light scattering processing can be visually recognized from the screen side, high in-plane (light-emitting area) average brightness can be secured.

  In the surface light source device of the present invention, in addition to the light guide plate, the point light source, and the frame, an optical element generally employed in a so-called edge light type surface light source device such as a diffusion sheet and a reflection sheet can be further included. Specifically, the diffusion sheet can be disposed above the light exit surface of the light guide plate, and the reflection sheet can be disposed below the facing surface of the light guide plate. Furthermore, above the light exit surface of the light guide plate, in addition to the diffusion sheet, a polarizing sheet for avoiding optical loss in a prism sheet, a condensing sheet such as a lenticular lens sheet and a micro lens sheet, and a polarizing plate of a liquid crystal panel A reflection sheet or the like can also be arranged.

  In particular, when a lens sheet having a groove structure having a ridge line substantially perpendicular to the light incident surface on which the LEDs are arranged is laminated above the light exit surface of the light guide plate, the luminance unevenness reducing effect of the present invention is very strong. Since it is obtained, the lens sheet is preferably a prism sheet in which the groove structure is formed of a substantially triangular prism. In addition, it is preferable to combine a lens sheet having a groove structure having a ridge line substantially parallel to the light incident surface on which the LEDs are disposed, since luminance unevenness when viewed from an oblique direction is improved. In this case, it is preferable to interpose a diffusion sheet between the prism sheet and the light guide plate because light scattering processing of the light guide plate becomes difficult to be visually recognized and fine unevenness is improved. Further, in order to prevent the optical sheet from being damaged due to interference with the display panel used in combination, a diffusion sheet is provided on the outermost side (the diffusion property is lower than the diffusion property of the diffusion sheet described above). It is preferable to dispose.

In the surface light source device of the present invention, in particular, a prism sheet having, on the surface thereof, a groove structure having at least a ridge line substantially perpendicular to the light incident surface on which the diffusion sheet and the LED are disposed above the light exit surface of the light guide plate. When four optical sheets, a prism sheet having a groove structure having a ridge line substantially parallel to the light incident surface on which the LEDs are arranged, and a diffusion sheet, are laminated in this order (see FIG. 22 ), luminance is increased. A very high-quality surface light source device is obtained in which there is almost no unevenness and the light scattering processing provided on the light guide plate is not visually recognized.

As the prism sheet and the diffusion sheet, those generally used in a surface light source device or the like can be used. For example, as a diffusion sheet (hereinafter referred to as “lower diffusion sheet”) in contact with the light exit surface of the light guide plate, the total thickness is 215 μm, and the breakdown is several μm to several on the display surface side on the 188 μm thick PET substrate. Transparent particles such as silica beads of the order of 10 μm are dispersed, and the beads are coated with UV or thermosetting resin as a binder around 10 μm thick (wherein most of the beads are coated so as to protrude from the binder). Thus, an appropriate diffusibility and light collecting property are obtained), and a coating layer for preventing charging and adhesion is provided on the opposite side as viewed from the display surface side with a thickness of about 10 μm (by the coating layer, This prevents problems caused by adhesion to the light guide plate, etc. A small amount of beads and a fatty acid salt for reducing the surface resistance are added to this coating layer. That.
The diffusion sheet disposed on the display surface side (hereinafter referred to as “upper diffusion sheet”) has a total thickness of 220 μm, and the breakdown is several μm to several tens of μm on the display surface side on the 188 μm thick PET substrate.
Transparent particles such as m-order silica beads are dispersed less than the lower diffusion sheet, and the beads are coated with a UV or thermosetting resin around 10 μm thick as a binder (where most of the beads are embedded in the binder) It is coated to prevent damage due to interference with the panel, etc. while suppressing appropriate diffusivity.) On the opposite side as seen from the display surface side, it prevents charging and adhesion as well as the lower diffusion sheet. (The coating layer prevents defects due to adhesion to the prism sheet. The coating layer includes a small amount of beads and a fatty acid salt for reducing surface resistance.) In the case of an upper diffusion sheet, the display surface side often takes the same design from the viewpoint of preventing adhesion to the panel.) Can do.

  As the prism sheet, for example, an optical sheet in which a UV curable resin is formed on a display surface side of a PET substrate having a thickness of 250 μm and a prism having a thickness of 15 μm to 20 μm and an apex angle of approximately 90 ° is formed at a pitch of approximately 50 μm. Can be used. On the opposite side when viewed from the display surface side, a coating layer for preventing charging and adhesion is provided in a thickness of 15 μm to 20 μm like the diffusion sheet, and adhesion with other laminated optical sheets and friction It prevents problems such as scratches due to increased coefficients. A small amount of beads and a fatty acid salt for reducing the surface resistance are added to this coat layer.

  The surface light source device may include a power source that supplies power to the point light source, and may include a control circuit that controls the amount of current and on / off.

The surface light source device of the present invention can also be used as a general lighting device. The case where the surface light source device of the present invention is used for a general lighting device will be described below.
FIG. 82 shows a cross-sectional view of an example of the lighting device of the present invention (indoor ceiling lighting), and FIG. 9 shows a schematic diagram thereof.
The illumination device C2-9 of the present invention includes a frame C2-90 (not shown in FIG. 9) having an opening C2-901 that defines a light emitting area (irradiation area), a light guide plate C2-91, and a light guide plate. And a plurality of point light sources (not shown in FIG. 82 ) arranged in the vicinity of the light incident surface (the back surface of the frame).

Even when the surface light source device of the present invention is used as a general lighting device, the point light source is not limited, but an LED (light emitting diode) is preferably used. Since the LED can obtain high-luminance light with low power consumption and emit light brightly even when the room temperature is low, it is possible to provide an illumination device having sufficient illuminance immediately after lighting. There is no limitation on the type of LED, for example, a one-chip type pseudo white LED that excites green and red phosphors (or yellow phosphors such as YAG) by blue LEDs, and two or more blue LED chips in one LED package 2in1 pseudo white LED that excites green and red phosphors (or yellow phosphors such as YAG), multi-color chip type that combines red / green / blue LEDs to produce white light, and near ultraviolet LED A one-chip type pseudo white LED in which red / green / blue phosphors are combined is exemplified.
FIG. 10 shows a schematic diagram of an example of a box-type LED 10 that can be used. There is no limitation on the outer shape of the LED and the size of the light emitting surface. In the backlight of a liquid crystal display device or the like, the outer shape is generally about 5.6 mm (width) × 3.0 mm (height) × 1.0 mm (thickness), and the width 102 of the light emitting surface 101 is generally 5 mm or less. However, in general lighting devices, those slightly larger than those used in backlights such as liquid crystal display devices are preferable, and the outer shape is 6.0 mm (width) × 5.0 mm (height) × 1. It is preferable that the width 102 of the light-emitting surface 101 is about 5.5 mm (thickness) or less and about 5.5 mm or less.
Moreover, although the supply current of a general LED is about 20 mA to 160 mA, a large chip type high output LED having a supply current of 200 mA to 1 A class can also be used in a general lighting device. When such a high-power LED is used, the number of LEDs to be used is drastically reduced and the manufacturing cost is reduced. On the other hand, the problem of hot spots is increased. Therefore, the effect of the present invention of reducing hot spots becomes more important.

The distance between the light emitting surface of the point light source and the light incident surface of the light guide plate is preferably 0.1 mm or more and 1.5 mm or less. More preferably, it is 0.3 mm or more and 1.0 mm or less.
This is because if the distance between the light guide plate and the light emitting surface is increased, the amount of light incident on the light guide plate is reduced by the inverse square law, and as a result, the total amount of light emitted from the light exit surface is also reduced. Therefore, the distance between the light emitting surface of the point light source and the light incident surface of the light guide plate is preferably close. Further, since heat is generated around the point light source and the light guide plate expands, it is necessary to leave a gap that can withstand the expansion.

Although there is no limitation on the arrangement method of the point light source, it is arranged on the straight line along the light incident surface of the light guide plate (parallel to the light emitting surface) at regular intervals (“equal interval” includes an error of ± 10%). It is preferable to do. In this case, the arrangement pitch P of the point light sources can be, for example, about the width (outer shape) of the point light source to about 200 mm. From the viewpoint of preventing luminance unevenness, the point light sources are preferably arranged as densely as possible, and it is preferable that the distance is increased to some extent from the viewpoint of mounting restrictions on the substrate and manufacturing cost. The arrangement pitch of the point light sources is preferably 6 mm to 200 mm, more preferably 10 to 100 mm.
However, in the present invention, a light guide plate in which luminance unevenness in the vicinity of the light incident surface on the light exit surface is reduced is used as the light guide plate. Therefore, even if the arrangement pitch of the point light sources is somewhat large, specifically, 80 mm to 200 mm. Even if it is about 100 mm to 200 mm, or about 120 mm to 200 mm, a light exit surface with suppressed hot spots can be realized.

The frame may be configured such that the light guide plate or the point light source can be accommodated therein, whereby the light source or the like can be hidden behind the frame to make the lighting device have a clean appearance.
Since luminance unevenness occurs in the vicinity of the light incident surface of the light guide plate, the opening of the frame is preferably designed such that the light emitting area starts from the inside of the light incident surface of the light guide plate.
That is, the horizontal distance G between the light incident surface 93 of the light guide plate 91 and the opening of the frame (the region 94 and the light incident surface 93 when the region 94 corresponding to the frame opening is projected on the light guide plate 91) Is preferably designed so as to ensure a certain distance (see FIG. 9).

However, in the light guide plate of the present invention, the luminance unevenness in the vicinity of the light incident surface is reduced. Therefore, in a general lighting device using the light guide plate, it is necessary to form the light emitting area on the inner side as the conventional light guide plate is used. No (no need to increase G).
Specifically, the horizontal distance G between the light incident surface of the light guide plate and the display area can be set to G <P (P / G> 1) with respect to the arrangement pitch P of the point light sources. May be G <P / 2 (P / G> 2), or G <P / 4 (P / G> 4).
If the relationship between P and G can be designed as described above, a stylish lighting device with a thin frame can be realized, and the number of point light sources to be used can be reduced. I can plan. In addition, although the magnitude | size of G is decided by balance with P as above-mentioned, it can be set to 0.1-30 mm, 0.1-20 mm, or 0.1-10 mm, for example.
In addition, as shown in the Example mentioned later, even if it changes the arrangement pitch P of a point light source, or even if the horizontal distance G between the light-incidence surface of a light-guide plate and a light emission area is changed, P / G will be. If the value is the same, the same luminance unevenness reduction performance is exhibited.

When the light guide plate has two light incident surfaces, the arrangement pitch of the point light sources arranged near the first light incident surface is P1, and the arrangement pitch of the point light sources arranged near the second light incident surface is P1 / G1: where P2, the horizontal distance between the first light incident surface and the opening is G1, and the horizontal distance between the second light incident surface and the opening is G2. P2 / G2 = 100: 90 to 100: 110 is preferable, P1 / G1: P2 / G2 = 100: 95 to 100: 105 is more preferable, and P1 / G1 = P2 / G2 is preferred.
G1 and G2 are not necessarily the same.

  The general lighting device may further include optical elements such as a diffusion sheet and a reflection sheet in addition to the light guide plate and the point light source. Specifically, the diffusion sheet can be disposed so as to face the light exit surface side of the light guide plate, or the reflection sheet can be disposed so as to face the facing surface side of the light guide plate. In addition to the diffusion sheet, a light collecting sheet such as a prism sheet, a lenticular lens sheet, or a microlens sheet can be disposed on the light exit surface side of the light guide plate. In addition, a power source that supplies power to the point light source may be included, and a control circuit that controls the amount of current and on / off may be included.

In the general lighting device, a cover may be provided on the light exit surface side of the light guide plate for the purpose of preventing contamination.
When used as an evacuation guide light ( FIG. 83 ), a panel for displaying the evacuee's guidance direction is disposed on the light exit surface side of the light guide plate.

When the surface light source device of the present invention is used as a general lighting device, the maximum luminance is not limited, but the luminance unevenness is improved in the surface light source device of the present invention. If the brightness of the bright part is equal to or less than the surface brightness of the HCFL (hot cathode tube, so-called fluorescent lamp) widely used in general lighting devices, the performance as general lighting is sufficient. In addition, the user is not dazzled. From such a point of view, in the general lighting device using the surface light source device of the present invention, the maximum luminance of the light emitting surface when lighting a plurality of point light sources is 10,000 cd / m ² or less regardless of which direction is measured. It is preferably 8,000 cd / m ^{2 to} 10,000 cd / m ^2, more preferably 9,000 cd / m ^{2 to} 10,000 d / cm ² .

Next, the display device of the present invention will be described.
A display device according to the present invention includes a display panel having a display area for displaying light by adjusting light transmission of the surface light source device, a light shielding frame for defining the display area, and a surface light source device disposed on the back surface of the display panel. And have.
In the display device of the present invention, the surface light source device described above can be used as the surface light source device.

The display area (active area) of the display panel should be designed to start from the inside of the light incident surface of the light guide plate, because uneven brightness occurs near the light incident surface of the light guide plate and sufficient display quality cannot be guaranteed. Is preferred.
That is, the horizontal distance G between the light incident surface 93 of the light guide plate 91 and the display area (the distance between the region 94 and the light incident surface 93 when the region 94 corresponding to the display area is projected on the light guide plate 91 ( It is preferably designed to ensure a certain level or more).

  However, since the light guide plate of the present invention has reduced luminance unevenness in the vicinity of the light incident surface, in the display device of the present invention using the light guide plate, the display area is formed on the inner side as the conventional light guide plate is used. There is no need to do this (G need not be increased).

  Specifically, in the display device of the present invention, the horizontal distance G between the light incident surface of the light guide plate and the display area is set to G <P / 2.5 (P /G>2.5), or G <P / 3 (P / G> 3) and G <P / 4 (P / G> 4).

  If the relationship between P and G can be designed as described above, a stylish display device in which the outer frame portion of the display area formed on the display panel called a frame is thin can be realized and used. Since the number of point light sources can be reduced, power can be saved. It should be noted that the relationship between P and G in the conventional display device is at most about P / G ≦ 0.7. In addition, although the magnitude | size of G is decided by balance with P as above-mentioned, it can be set to 0.1-30 mm, 0.1-20 mm, or 0.1-10 mm, for example.

  Even if the arrangement pitch P of the point light sources is changed or the horizontal distance G between the light incident surface of the light guide plate and the display area is changed, if the P / G is the same value, the same luminance unevenness reduction performance Indicates.

  When the light guide plate included in the display device of the present invention has two light incident surfaces, the arrangement pitch of the point light sources disposed in the vicinity of the first light incident surface is P1, and is disposed in the vicinity of the second light incident surface. The arrangement pitch of the point light sources is P2, the horizontal distance between the first light incident surface and the display area is G1, and the horizontal distance between the second light incident surface and the display area is G2. P1 / G1: P2 / G2 = 100: 90 to 100: 110 is preferable, and P1 / G1: P2 / G2 = 100: 95 to 100: 105 is preferable. More preferred.

  G1 and G2 are not necessarily the same. For example, since a speaker or the like may be provided on the lower side portion of the display device, it is possible to reduce G only on the lower side portion in order to secure a space.

  The display panel is preferably a liquid crystal display panel. Conventionally used liquid crystal display panels can be used as the liquid crystal display panel. An example of the configuration is schematically shown in FIG. 11 and described below.

  FIG. 11 is a schematic front view of an example of the liquid crystal display panel 11. The outer side of the dotted line 111 is a light shielding frame (black matrix) 113, and the inner side is a display area 112. Panel wiring (not shown) and the like exist behind the light shielding frame (black matrix) 113. In FIG. 11, reference numerals 114 and 115 denote a source chip which is a driver IC for applying a voltage to a source line (described later, not shown) and a voltage for applying a voltage to a gate line (described later, not shown). It is a gate chip which is a driver IC.

  In a transmissive liquid crystal display panel, generally, a large number of pixel electrodes arranged in a matrix on a transparent substrate are driven by active matrix elements arranged on the transparent substrate. An active matrix substrate in which an active matrix element and pixel electrodes are provided on a transparent substrate is provided with a liquid crystal layer in a stacked state, and a counter substrate is disposed so as to face the active matrix substrate with the liquid crystal layer interposed therebetween. ing. The counter substrate is a transparent substrate provided with a counter electrode, and this counter electrode is opposed to the display region in the liquid crystal layer.

  The active matrix element provided on the active matrix substrate is provided with a TFT (thin film transistor) as an active element connected to each pixel electrode. The active matrix element includes a plurality of gate lines arranged in parallel to each other along the row direction and a plurality of source lines arranged in parallel to each other along the column direction orthogonal to each gate line. Each TFT is disposed in the vicinity of the intersection between each gate line and each source line. Each TFT is connected to each of a gate line and a source line that form adjacent intersections.

  Each TFT is configured to be turned on by a gate signal supplied from a gate line to which each TFT is connected, and to supply a source signal supplied from a source line to which each TFT is connected to a pixel electrode connected thereto. Has been.

  In such a liquid crystal display panel, gate signals (horizontal synchronization) are usually line-sequentially arranged in the order along the column direction for each gate line arranged along the row direction on the active matrix substrate for each frame. Signal), and gate signals are continuously supplied to gate lines adjacent in the column direction.

The display panel of the display device of the present invention has a light shielding frame that defines a display area of the display device.
The light shielding frame is made of a material that does not transmit the light from the point light source, and the region corresponding to the display area is an opening or is made of a material that transmits the light from the point light source. A specific example of such a light shielding frame includes a glass substrate on which a color filter mixed with a light shielding agent such as carbon black is applied only to a region (frame portion) other than the display area.

The light shielding frame is configured so that the display area of the display device starts from the inside of the light incident surface of the light guide plate, and the display area is provided near the light incident surface of the light guide plate and / or the opposing surface. The light scattering degree of the region facing the light source is configured to start from the inner side of the light scattering processing configured to be lower than the light scattering degree of the region facing the part between the light source and the light source.
In other words, the region where the light scattering surface of the light exit surface and / or the opposing surface of the light guide plate is subjected to the light scattering processing is outside of the line facing the inner frame of the light shielding frame on the at least one light incident surface side, preferably 0. 10 mm (however, 0 mm is not included), more preferably 1 to 6 mm, still more preferably 1 to 4 mm, and particularly preferably 2 mm outside. In this way, there is no possibility that the start line of the light scattering process can be visually recognized from the screen side, and high in-plane (display area) average luminance can be ensured.

  The display device of the present invention can be used for various applications such as a portable information terminal and a monitor of a personal computer. For example, by combining the display device of the present invention with a tuner that receives a broadcast video signal, the television receiver of the present invention can be obtained. FIG. 12 shows an example of the configuration of such a television receiver 12. 12 includes a display cabinet 121 of the present invention, a front cabinet 122 provided with a speaker 1221; various circuit boards such as a television tuner circuit board 123, a power supply circuit board 124, and a control circuit board 125; 126, stand 127 and the like.

Next, a resin layer (light diffusion layer) which is bonded to the light incident surface of the light guide plate used in the present invention and has a plurality of concave portions or convex portions having an anisotropic shape with a long opening or bottom surface in one direction. The first invention of the present application relating to the light diffusing layer of the diffusing sheet, which can also be suitably used as a).
Description 1st invention relates to the diffusion sheet used for back lighting, such as a liquid crystal display device, especially to the light-diffusion layer.

Currently, liquid crystal display devices are used in a wide range of fields such as mobile phones, PDA terminals, digital cameras, televisions, personal computer displays, and notebook computers.
When the light source unit used in the liquid crystal display device is roughly classified, when the liquid crystal display panel arrangement side is set to the upper side, a direct type light source unit having a configuration in which a plurality of light sources are arranged directly under the liquid crystal display panel, and an arrangement directly under the liquid crystal panel There is an edge light type light source unit having a configuration in which a light source is arranged on the side end face of the light guide.

The light source unit used in the various liquid crystal display devices as described above is required to supply uniform light to the liquid crystal display panel and supply as much light as possible in order to make the display image easy to see.
That is, the light source unit is required to have optical characteristics that are excellent in light diffusibility and high brightness.

By the way, in the edge light type light source unit described above, since the light source is arranged on the side end surface of the light guide, the light source unit itself can be thinned. However, the luminance is lowered by passing the light guide. It has the disadvantage of becoming.
On the other hand, the direct type light source unit has an advantage that high luminance can be obtained, but has a disadvantage that the luminance between the upper part of the light source on the liquid crystal display panel surface and the upper part between the light sources tends to be uneven. have. Therefore, in the direct type light source unit, an optical sheet having a function of diffusing light with a certain distance between the light source and the liquid crystal display panel, for example, a diffusion plate, is disposed between the light source and the liquid crystal display panel. I am doing so.

  As the diffusing plate, a resin plate containing light diffusing particles and bubbles, or a structure having a fine uneven shape on the surface of a transparent substrate are known. The latter with less loss of light transmittance is more preferable.

  As a method of imparting the uneven shape to the surface of the diffusion plate, there are a method of injection molding a resin using a predetermined mold, and a method of processing the uneven structure into a roll with a diamond blade and extrusion using the method. is there.

However, the method of mechanically forming the unevenness as described above has a problem that it takes a lot of time and is expensive. Further, in the method of mechanically forming the unevenness as described above, there is a problem that the structure of about several tens of μm is the limit, and further, it is not easy to improve the shape uniformity.
On the other hand, the concave / convex shape is recorded on the photosensitive medium by the speckle of the laser beam, and a mold for pattern transfer is manufactured. A technique for forming a holographic light guide plate by forming irregularities on the surface is proposed (see, for example, FIG. 41 in JP-A-2001-23422).

On the other hand, in recent years, liquid crystal display devices have been made thinner, and the distance between a light source and an optical sheet (for example, the above-described hologram light guide plate and diffusion plate) for diffusing light from the light source. There is a request to make more.
There is also a demand to reduce the number of light sources in the light source unit in order to reduce cost and power consumption.

However, as schematically shown in FIGS. 57A and 57B, in the light source unit, the ratio (p /) between the pitch (p) of the light source and the distance (h) between the light source B1 and the optical sheet B2. As h) becomes larger, that is, as h becomes smaller (ha in FIG. 57 (a)) and / or p becomes larger (pa in FIG. 57 (b)), the luminance unevenness becomes more conspicuous.
Here, “brightness unevenness” refers to a phenomenon in which light and darkness derived from the intensity distribution of light source illuminance can be seen on the screen of a liquid crystal display panel.
Liquid crystal display devices are required to reduce such luminance unevenness.

In the prior art disclosed in Japanese Patent Laid-Open No. 2001-23422, the luminance unevenness cannot be sufficiently reduced, and the liquid crystal display device cannot be made thin and the number of light sources can be reduced.
SUMMARY OF THE INVENTION In view of the above-described problems of the prior art, the object of the present invention is to provide a diffusion sheet and a light source unit that can reduce luminance unevenness.

The inventor of the specification first invention has intensively studied to solve the above-described problems of the related art relating to the diffusion sheet. As a result, the light diffusion layer is formed of a specific material and has a specific refractive index. The inventors have found that the above-described problems of the prior art can be solved by the diffusion sheet, and have completed the first invention of the specification.
The first invention of the specification is as follows.

[1]
A diffusion sheet in which a resin layer having an uneven structure is laminated on at least one main surface of a sheet-like base material,
The refractive index of the resin layer is 1.55 to 1.70,
And the resin layer is
Photopolymerizable resin containing (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group: 70 to 99.9% by mass, and (B) photopolymerization initiator: 0.1 to 30% by mass Consisting of a cured product of the composition,
The diffusion sheet containing (A) a compound having a structure represented by the following general formula (I) in which the addition polymerizable monomer having at least one terminal ethylenically unsaturated group has a biphenyl group.

Formula (I)

(In general formula (I), R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.)

  The compound having the structure represented by the general formula (I) is preferably a compound represented by the following general formula (II).

Formula (II)

  In general formula (II), R represents a hydrogen atom or a methyl group, A represents a C1-C4 alkylene group each independently, and n represents an integer of 1-3.

[2]
The content of the compound having the structure represented by the general formula (I) or (II) in the addition polymerizable monomer (A) having at least one terminal ethylenically unsaturated group is 50 to 95% by mass. The diffusion sheet according to [1].

[3]
The diffusion sheet according to [1] or [2], wherein a diffusion angle periodically changes along a predetermined direction in the surface of the diffusion sheet when a light beam is incident on the surface of the diffusion sheet in a vertical direction.

[4]
In the diffusion angle distribution diagram taking the relative position in the predetermined direction in the diffusion sheet surface on the horizontal axis, the diffusion angle in the relative position on the vertical axis,
There are a plurality of peak points at which the diffusion angle indicates a peak value and a plurality of bottom points at which the diffusion angle indicates a bottom value, and the arithmetic average value of the peak value and the bottom value indicated by the adjacent peak point and the bottom point is The diffusion sheet according to [3], which is larger than an arithmetic average value of diffusion angles at all points distributed between the adjacent peak point and bottom point.

[5]
The diffusion sheet according to any one of [1] to [4], wherein a diffusion angle is controlled by the uneven structure.

[6]
The concavo-convex structure is a concavo-convex structure formed using a speckle pattern by interference exposure, and the diffusion angle is controlled by the average size and shape of speckles of the concavo-convex structure. ] The diffusion sheet as described in any one of.

[7]
A light source unit comprising two or more light sources and the diffusion sheet according to any one of [1] to [6] disposed to face the light sources.

[8]
The light source unit according to [7], wherein the light source is a linear light source.

[9]
The light source unit according to [7], wherein the light source is a point light source.

[10]
A period of diffusion angle distribution of the diffusion sheet;
Period of illuminance distribution on the light incident surface of the diffusion sheet;
Is the light source unit according to any one of [7] to [9].

[11]
A diffusion plate containing a diffusing agent is disposed between the diffusion sheet and the light source, and a reflection sheet is disposed on the opposite side of the diffusion plate from the light source via the light source. [7] The light source unit according to any one of [10].

[12]
The light source unit according to any one of [7] to [11], wherein a surface-shaped diffusion sheet is further arranged on the diffusion sheet arrangement side.

[13]
The light source unit according to any one of [7] to [12], wherein a prism sheet is further arranged on the diffusion sheet arrangement side.

[14]
The light source unit according to any one of [7] to [13], wherein a reflective polarizing sheet is further arranged on the diffusion sheet arrangement side.

[15]
A liquid crystal display panel, and the light source unit according to any one of [7] to [14] for supplying light to the liquid crystal display panel,
A liquid crystal display device in which the light source unit is disposed on the back side of the liquid crystal display panel, and display is performed by entering light from the light source unit.

  According to the first invention of the specification, a diffusion sheet, a light source unit, and a liquid crystal display device using the diffusion sheet that can effectively reduce luminance unevenness can be obtained.

Hereinafter, modes for carrying out the specification first invention (hereinafter referred to as embodiments) will be described with reference to the drawings.
In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.
Further, in each drawing, unless otherwise specified, the positional relationship such as up, down, left, and right is based on the positional relationship shown in the drawing, and the dimensional ratio in the drawing is not limited to the illustrated ratio.
Furthermore, in the present specification, the term “abbreviated” indicates the meaning of the term excluding the “abbreviation” within the scope of technical common knowledge of those skilled in the art, Shall also be included.

[Diffusion sheet]
In the diffusion sheet of the embodiment, a resin layer having a concavo-convex structure is laminated on at least one main surface of a sheet-like substrate.
The refractive index of the resin layer is 1.55 to 1.70,
And the resin layer is
(A) Addition polymerizable monomer having at least one terminal ethylenically unsaturated group: 70 to 99.9% by mass, (B) Photopolymerization initiator: Photopolymerizable resin composition containing 0.1 to 30% by mass Made of cured products,
The (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group contains a compound having a structure represented by the following general formula (I) having a biphenyl group.

Formula (I)

(In general formula (I), R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.)

  The compound having a structure represented by the general formula (I) preferably has a structure represented by the following general formula (II).

Formula (II)

  In general formula (II), R represents a hydrogen atom or a methyl group, A represents a C1-C4 alkylene group each independently, and n represents an integer of 1-3.

(Base material)
The base material constituting the diffusion sheet of the embodiment is a sheet-like base material, and may be a light-transmitting base material made of a material such as resin or glass. In particular, the light transmittance of the base material alone is 75. % Or more is preferable.
In this case, “light” is not particularly limited as long as it is visible light, but is, for example, light emitted from a light source in a light source unit using the diffusion sheet of the embodiment.
The light transmittance is determined by, for example, using a UV-visible spectrophotometer (MPC-2200) manufactured by Shimadzu Corporation, and setting the base material between the light source and the detector, and the incident light intensity at a wavelength of 550 nm. And after detecting transmitted light intensity, it is computable by following formula (II).
Light transmittance (%) = (transmitted light intensity at 550 nm) / (incident light intensity at 550 nm) × 100 (II)
Although the thickness of a base material is not specifically limited, Usually, it exists in the range of 50 micrometers-500 micrometers.
Examples of the resin material of the substrate include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, acrylic resins such as polymethyl methacrylate, thermoplastic resins such as polycarbonate resin, polystyrene resin, and polymethylpentene resin, and polyester. Examples include resins obtained by curing an ionizing radiation curable resin composed of oligomers such as acrylate, urethane acrylate, epoxy acrylate, and / or acrylate monomers with electromagnetic radiation such as ultraviolet rays or electron beams.
As the glass, soda glass, borosilicate glass, or the like is used.

(Resin layer)
<Uneven structure>
The resin layer is formed on at least one main surface of the base material described above and has a concavo-convex structure.
The said main surface means the surface and the back surface when not including the thickness part of the base material mentioned above and seeing a base material as a plane.
The uneven structure is a structure in which a large number of protrusions are provided on the surface.
The shape of the protrusion is not particularly limited, and examples thereof include a substantially conical shape, a substantially spherical shape, a substantially ellipsoidal shape, a substantially lenticular lens shape, and a substantially parabolic shape.
The protrusions may be regularly arranged or irregularly arranged. Further, the protrusions may be connected by a continuous curved surface.
Further, a pseudo random structure in which irregular irregularities are connected by a continuous curved surface can also be preferably used. This pseudo-random structure is preferably a fine three-dimensional structure characterized by non-planar speckles.

  In order to obtain favorable characteristics regarding the light diffusion performance, the height of the protrusions is preferably in the range of 1 μm to 15 μm, and the pitch is preferably in the range of 1 μm to 30 μm.

The three-dimensional structure characterized by the non-planar speckle is suitable for forming a fine concavo-convex structure of 10 μm or less, which is difficult by machining.
In particular, the method of forming irregularities using non-planar speckles is a manufacturing method suitable when the diffusion angle is changed according to the region on the diffusion sheet.
A method for manufacturing the concavo-convex structure using this non-planar speckle will be described later.

  An isotropic uneven structure such as a microlens and an anisotropic uneven structure such as a lenticular lens are also preferable as the uneven structure of the resin layer of the diffusion sheet.

The uneven structure formed in the resin layer of the diffusion sheet preferably has an irregular height and pitch from the viewpoint of suppressing moire.
When the uneven shape is present on the surface of the sheet, it becomes possible to diffuse the light incident on the diffusion sheet.

  The diffusion sheet of the embodiment may be any part of the sheet surface where the uneven shape as described above is arranged and has a portion showing a function of diffusing light, and a portion that does not need to have a diffusion function, for example, an end In the portion, there may be a portion where the sheet surface is smooth.

<Refractive index>
The refractive index of the resin layer of the diffusion sheet of the embodiment is 1.55 to 1.70.
The refractive index of the resin layer is measured according to JIS K7142, and specifically, can be measured using a refractometer MODEL 2 010 PRISM COUPLER (manufactured by Metricon) manufactured by Metricon.
If the refractive index of the resin layer is 1.55 or more, light from the light source can be efficiently launched, and uneven brightness can be effectively reduced.
If the refractive index is 1.70 or less, (1) introducing a halogen such as chlorine or bromine into the addition polymerizable monomer molecule, (2) introducing an inorganic molecule into the composition, (3) into the composition It can be produced without using a technique such as adding a large amount of an addition polymerizable monomer having a specific structure such as a bisphenol skeleton or a fluorene skeleton. In the case of (1), the burden on the environment is high. In the case of (2), compatibility and moldability as a resin are deteriorated. In the case of (3), the resin viscosity becomes high and handling is difficult. Each has the demerits that it becomes difficult, the curing shrinkage is too large, the transferability is inferior, and the cured resin is too hard and the impact resistance is inferior. The refractive index of the resin layer is preferably 1.58 to 1.70, more preferably 1.60 to 1.70.
When the refractive index is in the range of 1.55 to 1.70, even if the concavo-convex structure is the same as the dimensional shape, the light diffusibility is relatively high compared to the case where the refractive index is low. A diffusion sheet having a high diffusion angle can be realized more easily.
Moreover, the brightness nonuniformity suppression effect of a backlight can be heightened by using the diffusion sheet of embodiment which comprises the resin layer which has a refractive index as mentioned above for a direct type light source unit. Furthermore, when the refractive index of the resin layer having a concavo-convex structure is in the range of 1.55 to 1.70, even if the dimensional shape is the same concavo-convex structure, it is incident obliquely compared to the case where the refractive index is low. Since it becomes easy to raise light directly above, it becomes possible to improve the brightness | luminance of a backlight, for example in an edge light type light source unit.

<Material of resin layer>
The resin constituting the resin layer of the diffusion sheet of the embodiment is a cured product of the photopolymerizable resin composition.
The photopolymerizable resin composition comprises (A) 70-99.9% by mass of an addition polymerizable monomer having at least one terminal ethylenically unsaturated group, and (B) a photopolymerization initiator: 0.1-30% by mass. %.

(A) As the addition polymerizable monomer having at least one terminal ethylenically unsaturated group, a compound having a known (meth) acrylate group or allyl group can be used. For example, nonylphenol acrylate, alkoxylation (1) o-phenylphenol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, β-hydroxypropyl-β ′-(acryloyloxy) propyl phthalate, 1,4-tetramethylene glycol di ( (Meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, octapropylene glycol di (meth) acrylate, glycerol (meth) acrylate, 2-di (p-hydroxy) Phenyl) propane di (meth) acrylate, glycerol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, polyoxypropyltrimethylolpropane tri (meth) acrylate Polyoxyethyltrimethylolpropane tri (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane triglycidyl ether tri (meth) acrylate, bisphenol A diglycidyl ether di (Meth) acrylate, diallyl phthalate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, bis (triethylene glycol methacrylate) nonapropylene glycol, bis (tetraethylene glycol methacrylate) polypropylene glycol, bis (triethylene glycol) Methacrylate) polypropylene glycol, bisarylfluorene derivatives, bis (diethyl) (Lene glycol acrylate) polypropylene glycol, compounds containing both ethylene oxide chain and propylene oxide chain in the molecule of bisphenol A (meth) acrylate monomer. A urethanized compound of a polyvalent isocyanate compound such as hexamethylene diisocyanate or tolylene diisocyanate and a hydroxy acrylate compound such as 2-hydroxypropyl (meth) acrylate can also be used.
The urethanized compound in this case is preferably less than 10,000 in terms of polystyrene-reduced number average molecular weight by gel permeation chromatography (GPC).
The above-mentioned (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group may be used alone or in combination of two or more.
When combining 2 or more types, for example, by copolymerizing with methyl methacrylate, these (A) addition polymerizable monomers having at least one terminal ethylenically unsaturated group may be used as the side chain component of the PMMA polymer. For example, alkoxylated phenylphenol acrylate may be used as the side chain component of the PMMA polymer.
From the viewpoint of curing with high sensitivity to irradiated light, those having three or more (meth) acrylate groups are preferable. For example, triacrylate obtained by adding an average of 3 moles of ethylene oxide to trimethylolpropane (Shin-Nakamura Chemical A-TMPT-3EO, product name), pentaerythritol tetraacrylate (Shin-Nakamura Chemical A-TMMT, product name), ethoxy Pentaerythritol tetraacrylate (Shinnakamura Chemical ATM-35E, product name), dipentaerythritol pentaacrylate (Sartomer SR399, product name), ethoxylated (4) pentaerythritol tetraacrylate (Sartomer SR494, product name), etc. Is mentioned.
From the viewpoint of improving the adhesion between the cured resin and the substrate, 2-phenoxyethyl acrylate (Sartomer SR339A, product name), 2-phenoxyethyl methacrylate (Sartomer SR340, product name), alkoxylated tetrahydrofur Furyl acrylate (Sartomer CD611, product name), tetrahydrofurfuryl acrylate (Sartomer SR285, product name), tetrahydrofurfuryl methacrylate (Sartomer SR203, product name) and the like are preferable.
From the viewpoint of imparting flexibility to the cured product after light irradiation, a monomer having a urethane bond or an isocyanuric bond is preferable. For example, pentaerythritol triacrylate hexameric range isocyanate urethane prepolymer (UA306H manufactured by Kyoeisha Chemicals, product name), ε-caprolactone-modified tris (acryloxyethyl) isocyanurate (M-327 manufactured by Toagosei Co., Ltd.), polyol modified Bifunctional urethane acrylate (Kyoeisha Chemical M-1600, product name), bifunctional aliphatic urethane acrylate (Sartomer CN9001, product name), polyester-modified bifunctional urethane acrylate (Sartomer CN981, product name), polyester-modified trifunctional Examples thereof include urethane acrylate (CN929 manufactured by Sartomer, product name).
From the viewpoint of refractive index, 2-phenoxyalkyl (meth) acrylate, nonylphenol-modified (meth) acrylate, isocyanuric-modified (meth) acrylate, tricyclodecane-modified (meth) acrylate, and fluorene-modified (meth) acrylate are preferable. Examples of 2-phenoxyalkyl (meth) acrylate include 2-phenoxyethyl acrylate (Sartomer SR339A, product name), 2-phenoxyethyl methacrylate (Sartomer SR340, product name), and nonylphenol-modified (meth) acrylate. As ethoxylated (4) nonylphenol acrylate (M-113 manufactured by Toa Gosei, product name), 4-nonylphenylheptaethylene glycol dipropylene glycol acrylate (LS-100A manufactured by NOF, product name), isocyanuric modified (meta) Examples of acrylates include isocyanuric acid EO-modified di and triacrylate (M-315, M-313, product name) manufactured by Toagosei, and examples of tricyclodecane-modified (meth) acrylate include tricyclodecane dimethanol dimeta. Examples of Relate (DCP manufactured by Shin-Nakamura Chemical, product name), tricyclodecane dimethanol diacrylate (A-DCP manufactured by Shin-Nakamura Chemical, product name), and fluorene-modified (meth) acrylate include -(2-acryloyloxyethoxy) phenyl] fluorene (Shin-Nakamura Chemical A-BPEF, trade name or Osaka Gas Chemical BPEF-A) and its derivatives (Osaka Gas Chemicals, Ogsol EA-0200, Ogsol EA-0500, Ogsol EA-1000, Ogsol EA-F5003, Ogsol EA-F5503) and the like.
Moreover, the compound shown by the following general formula (X) is also preferable.

Formula (X)

(Wherein R ₁ and R ₂ are each independently H or CH ₃ , and A and B are each independently an alkylene group having 1 to 4 carbon atoms. A1, a2, b1 and b2 is 0 or a positive integer, and the sum of a1, a2, b1, and b2 is 2 to 40.)
Examples of the compound represented by the general formula (X) include 2,2-bis {(4-acryloxypolyethyleneoxy) phenyl} propane or 2,2-bis {(4-methacryloxypolyethyleneoxy) phenyl} propane. Can be mentioned. The polyethyleneoxy group possessed by the compound is monoethyleneoxy group, diethyleneoxy group, triethyleneoxy group, tetraethyleneoxy group, pentaethyleneoxy group, hexaethyleneoxy group, heptaethyleneoxy group, octaethyleneoxy group, nonaethylene It is any group selected from the group consisting of oxy group, decaethyleneoxy group, undecaethyleneoxy group, dodecaethyleneoxy group, tridecaethyleneoxy group, tetradecaethyleneoxy group, and pentadecaethyleneoxy group Compounds are preferred. Further, 2,2-bis {(4-acryloxypolyalkyleneoxy) phenyl} propane or 2,2-bis {(4-methacryloxypolyalkyleneoxy) phenyl} propane can be given. Examples of the polyalkyleneoxy group possessed by the compound include a mixture of an ethyleneoxy group and a propyleneoxy group, an adduct having a block structure or a random structure having an octaethyleneoxy group and a dipropyleneoxy group, and tetraethyleneoxy. An adduct having a block structure of a group and a tetrapropyleneoxy group or an adduct having a random structure, an adduct having a block structure of a pentadecaethyleneoxy group and a dipropyleneoxy group, or an adduct having a random structure is preferable. In the formula, a3, a4, b3 and b4 are 0 or a positive integer, and the total of a3, a4, b3 and b4 is preferably 2 to 30. Among these, ethoxylated bisphenol A dimethacrylate (manufactured by Shin-Nakamura Chemical, BPE-100, BPE-200, BPE-500, BPE-900, BPE-1300N, product names), ethoxylated bisphenol A diacrylate (Shin Nakamura Chemical) ABE-300, A-BPE-10, A-BPE-20, A-BPE-30, A-BPE-4, product name), propoxylated bisphenol A diacrylate (manufactured by Shin-Nakamura Chemical, A-BPP- 3, product name), propoxylated ethoxylated bisphenol A diacrylate (manufactured by Shin-Nakamura Chemical Co., A-B1206PE, product name) and 2,2-bis {(4-methacryloxypentaethyleneoxy) phenyl} propane are most preferred.
Among these, a compound represented by the following general formula (I) is preferred from the viewpoint of refractive index, and a compound represented by the following general formula (II) is most preferred.

Formula (I)

(In the formula, R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.)

Formula (II)

(In the formula, R represents a hydrogen atom or a methyl group, A independently represents an alkylene group having 1 to 4 carbon atoms, and n represents an integer of 1 to 3).

Examples of compounds represented by general formula (I) include alkylated (1) o-phenylphenol (meth) acrylate, alkylated (2) o-phenylphenol (meth) acrylate, alkylated (3) o-phenyl. Phenol (meth) acrylate, alkylated (4) o-phenylphenol (meth) acrylate, alkoxylated (1) o-phenylphenol (meth) acrylate, alkoxylated (2) o-phenylphenol (meth) acrylate, alkoxylated (3) o-phenylphenol (meth) acrylate, alkoxylation (4) o-phenylphenol (meth) acrylate, alkoxylation (5) o-phenylphenol (meth) acrylate, alkoxylation (6) o-phenylphenol ( (Meth) acrylate, alkenylation 1) o-phenylphenol (meth) acrylate, alkylation (1) alkoxylation (1) o-phenylphenol (meth) acrylate, alkylation (2) alkoxylation (2) o-phenylphenol (meth) acrylate, alkyl (2) alkoxylation (3) o-phenylphenol (meth) acrylate. Among these, alkoxylated (1) o-phenylphenol acrylate is preferable from the viewpoint of refractive index, and ethoxylated (1) o-phenylphenol acrylate (for example, product name A-LEN-10, manufactured by Shin-Nakamura Chemical) is particularly preferable. .
Further, in these compounds, a compound in which a residue is bonded to the meta position or para position in place of the ortho position of the biphenyl group, for example, ethoxylated (1) m-phenylphenol acrylate, ethoxylated (1) p-phenylphenol Acrylates are also preferred.

Examples of the compound represented by the general formula (II) include methoxylated (1) o-phenylphenol (meth) acrylate, methoxylated (2) o-phenylphenol (meth) acrylate, and methoxylated (3) o-phenyl. Phenol (meth) acrylate, ethoxylated (1) o-phenylphenol (meth) acrylate, ethoxylated (2) o-phenylphenol (meth) acrylate, ethoxylated (3) o-phenylphenol (meth) acrylate, propoxylated (1) o-phenylphenol (meth) acrylate, propoxylated (2) o-phenylphenol (meth) acrylate, propoxylated (3) o-phenylphenol (meth) acrylate, butoxylated (1) o-phenylphenol ( (Meth) acrylate, butoxylation ( ) O-phenylphenol (meth) acrylate, butoxy reduction (3) o-phenylphenol (meth) acrylate.
Among these, ethoxylated (1) o-phenylphenol acrylate (for example, product name A-LEN-10, manufactured by Shin-Nakamura Chemical Co., Ltd.) is preferable.

The content ratio of the compound represented by the general formula (I) or (II) in the addition polymerizable monomer (A) having at least one terminal ethylenically unsaturated group is 50 to 95% by mass. preferable.
From the viewpoint of increasing the refractive index of the resin layer, 50% by mass or more is preferable, and from the viewpoint of preventing a decrease in photocurability, the content is preferably 95% by mass or less.

As the above-mentioned (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group, in addition to the compound represented by the above general formula (I) or (II), a known (meth) acrylate group or allyl Compounds having groups can be used.
For example, nonylphenol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, β-hydroxypropyl-β ′-(acryloyloxy) propyl phthalate, 1,4-tetramethylene glycol di (meth) acrylate, 1,6-hexanediol di (Meth) acrylate, 1,4-cyclohexanediol di (meth) acrylate, octapropylene glycol di (meth) acrylate, glycerol (meth) acrylate, 2-di (p-hydroxyphenyl) propane di (meth) acrylate, glycerol tri ( (Meth) acrylate, trimethylolpropane tri (meth) acrylate, polyoxypropyltrimethylolpropane tri (meth) acrylate, polyoxyethyltrimethylolpropane tri (meth) Acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane triglycidyl ether tri (meth) acrylate, bisphenol A diglycidyl ether di (meth) acrylate, diallyl phthalate, polyethylene glycol di ( (Meth) acrylate, polypropylene glycol di (meth) acrylate, bis (triethylene glycol methacrylate) nonapropylene glycol, bis (tetraethylene glycol methacrylate) polypropylene glycol, bis (triethylene glycol methacrylate) polypropylene glycol, bis (diethylene glycol acrylate) polypropylene glycol , Bisphenol A-based (meth) ac Examples thereof include compounds containing both an ethylene oxide chain and a propylene oxide chain in the molecule of the acrylate monomer.

A urethanized compound of a polyvalent isocyanate compound such as hexamethylene diisocyanate or tolylene diisocyanate and a hydroxy acrylate compound such as 2-hydroxypropyl (meth) acrylate can also be used.
The urethanized compound in this case is preferably less than 10,000 in terms of polystyrene-reduced number average molecular weight by gel permeation chromatography (GPC).

  The above-mentioned (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group may be used alone or in combination of two or more.

  The content of the (A) addition polymerizable monomer in the photopolymerizable resin composition is 70% by mass or more and 99.9% by mass or less based on the total mass of the photopolymerizable resin composition. Preferably they are 75 mass% or more and 95 mass% or less. From the viewpoint of sufficient curing, the content is 70% by mass or more, and is 99.9% by mass or less in consideration of blending an initiator component, other polymerization inhibitors, dyes, and the like.

Examples of the photopolymerization initiator (B) in the photopolymerizable resin composition include benzyl dimethyl ketal, benzyl diethyl ketal, benzyl dipropyl ketal, benzyl diphenyl ketal, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, Benzoin phenyl ether, thioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 4-isopropylthioxanthone, 2,4-diisopropylthioxanthone, 2-fluorothioxanthone, 4-fluorothioxanthone, 2-chloro Thioxanthone, 4-chlorothioxanthone, 1-chloro-4-propoxythioxanthone, benzophenone, 4,4'-bis (dimethylamino) benzofe Aromatic ketones such as non [Michler's ketone], 4,4′-bis (diethylamino) benzophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one , Biimidazole compounds such as 2- (o-chlorophenyl) -4,5-diphenylimidazolyl dimer, acridines such as 9-phenylacridine, α, α-dimethoxy-α-morpholino-methylthiophenylacetophenone, 2,4 , 6-trimethylbenzoyldiphenylphosphine oxide, phenylglycine, N-phenylglycine, 1-phenyl-1,2-propanedione-2-O-benzoyloxime, ethyl 2,3-dioxo-3-phenylpropionate 2- (O-benzoylcarbonyl) -oxime Oxime esters such as p-dimethylaminobenzoic acid, p-diethylaminobenzoic acid, and p-diisopropylaminobenzoic acid, and esterified products thereof with these alcohols, p-hydroxybenzoic acid ester, 3-mercapto-1,2 Triazoles such as 1,4-triazole, tetrazoles, N-phenylglycine, N-phenyl-N-phenylglycine, N-phenylglycine such as N-ethyl-N-phenylglycine, and 1-phenyl-3- Styryl-5-phenyl-pyrazoline, 1- (4-tert-butyl-phenyl) -3-styryl-5
-Phenyl-pyrazoline, 1-phenyl-3- (4-tert-butyl-styryl) -5
And pyrazolines such as-(4-tert-butyl-phenyl) -pyrazoline.
Among these, 2-hydroxy-2-methyl-1-phenyl-propan-1-one (for example, product name DAROCURE 1173, manufactured by Ciba Specialty Chemical) is preferable.

The content of the photopolymerization initiator (B) in the photopolymerizable resin composition is 0.1% by mass or more and 30% by mass or less, preferably 1% by mass based on the total mass of the photopolymerizable resin composition. It is 20 mass% or less.
When the content of (B) is 0.1% by mass or more, sufficient photocuring sensitivity can be obtained, and when it is 30% by mass or less, storage stability as a liquid resin before photocuring is obtained. .

In order to improve thermal stability and storage stability, it is preferable to contain a radical polymerization inhibitor in the photopolymerizable resin composition.
Examples of such radical polymerization inhibitors include p-methoxyphenol, hydroquinone, pyrogallol, naphthylamine, t-butylcatechol, cuprous chloride, 2,6-di-t-butyl-p-cresol, 2,2 Examples include '-methylenebis (4-ethyl-6-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), and the like.
The content of the radical polymerization inhibitor is preferably 0.001% by mass or more and 1% by mass or less based on the total mass of the photopolymerizable resin composition.

(Diffusion sheet characteristics)
In the diffusion sheet of the embodiment, it is preferable that the diffusion angle is periodically changed along a predetermined direction in the plane when light rays are incident on the diffusion sheet surface vertically.
Thereby, since the diffusibility can be changed according to the illuminance distribution in the sheet surface, the effect that the luminance unevenness can be reduced more uniformly is obtained.

The diffusion sheet of the embodiment constitutes a light source unit to be described later by combining with a predetermined light source.
Here, in order to explain the optical function of the diffusion sheet, the relationship between the diffusion sheet and the light source of the embodiment in the light source unit will be described.
FIGS. 58A and 58B show the projection area of the light source and the projection area between the light sources when the light sources B101 and 102 are arranged facing the diffusion sheet B15, respectively.
When configuring the light source unit, other optical sheets having other predetermined functions can be arranged between the diffusion sheet B15 and the light sources B101 and 102. In FIGS. 58 (a) and (b), Is omitted.

A plurality (at least two) of light sources are arranged.
As the light source, a line light source such as a cold cathode fluorescent lamp (CCFL) B101 as shown in FIG. 58 (a), or a point light source such as an LED (light emitting diode) B102 or a laser as shown in FIG. 58 (b) . Can be used.
Figure 58 (a), (b), the reference numeral B103 denotes a projection area directly above the light source, reference numeral B104 denotes a projection area between the light sources.
The projection area directly above the light source requires high diffusivity, and the projection area between the light sources does not require high diffusivity. By dividing the area in this way, the diffusion angle can be designed reliably. .
In FIG. 58 (a), (b) , the entire region, and the projection region B103 of light right above light source, an example being divided into two and the projection region B104 between the light source, the light source directly above There may be an area other than the projection area B103 and the projection area B104 between the light sources, for example, end portions such as four corners.
Further, the projection area B104 between the light sources does not have to be adjacent to the projection area B103 immediately above the light source, and is an area located in the middle of the adjacent light sources (for example, a broken line in FIGS. 58A and 58B) . An intermediate region of the light source disposed along the light source).

The “diffusion angle” refers to an angle (FWHM: Full Width Half Maximum) that is twice the angle at which the transmitted light intensity attenuates to half of the peak intensity (half-value angle).
FIG. 59A is an explanatory diagram of the diffusion angle. The horizontal axis represents the outgoing angle of the transmitted light, and the vertical axis represents the transmitted light intensity (relative value).

This diffusion angle is, for example, Gotonometric Radiometers Real-Time manufactured by Photon Corporation.
It can be obtained by measuring the angular distribution of transmitted light intensity with respect to light incident from the uneven surface side, using the Far-Field Angular Profile Model LD8900 (hereinafter referred to as LD8900) from the normal direction of the uneven surface of the diffusion sheet B15.
Here, in FIG. 59B, transmitted light intensity is schematically shown when light is incident on the uneven surface side of the diffusion sheet B15 from the normal direction.

In addition, as the diffusion sheet of the embodiment, both an isotropic sheet capable of obtaining substantially the same diffusion angle regardless of the measurement direction and an anisotropic sheet having a different diffusion angle depending on the measurement direction can be used.
An anisotropic sheet is, for example, a sheet having different diffusion angles when the diffusion angles are measured in two orthogonal directions.

As described above, the diffusion sheet of the embodiment preferably has a diffusion angle that periodically changes along a predetermined direction in the sheet surface.
Here, “cyclically changing” means that the repeated patterns are compared with each other, and the peak value corresponding to the same repetition and the displacement from the start point of the period giving the peak value are the average value of all the repeated patterns. Within a range of ± 15% (preferably within 10%, more preferably within 5%), the bottom value and the displacement from the start point of the cycle giving the bottom value are ± 15% of the average value of all repeated patterns Within the range (preferably within 10%, more preferably within 5%), it corresponds to a periodically changing one.
The direction showing the periodicity may be at least one in the diffusion sheet surface, and can be specified by creating a distribution of diffusion angles on the diffusion sheet surface.
In the embodiment, the diffusion angle of a plurality of repeated peak values is preferably such that the difference in the diffusion angles of all the measured peak values is within 5 °, more preferably within 3 °, and within 2 °. Most preferably it is. The same applies to the bottom value.

The diffusion capability of such a diffusion sheet is represented by a diffusion angle distribution diagram in which the horizontal axis represents the relative position in the sheet surface in the predetermined direction, and the vertical axis represents the diffusion angle at the relative position in the sheet surface. be able to.
FIG. 60 is a diagram showing one cycle of the distribution of the diffusion angle with respect to the relative position in the surface of the diffusion sheet in the example of the diffusion sheet described above.
In this diffusion sheet, when a light beam is incident perpendicularly to the sheet surface, the diffusion angle of the emitted light periodically changes along a predetermined direction in the sheet surface.
In the diffusion angle distribution diagram shown in FIG. 60 , the horizontal position represents the relative position in the sheet surface in a predetermined direction within the diffusion sheet surface, and the vertical axis represents the diffusion angle at the relative position in the sheet surface.

The diffusion sheet of the embodiment preferably includes a plurality of peak points where the diffusion angle indicates a peak value and a plurality of bottom points where the diffusion angle indicates a bottom value (in FIG. 60 , there is one peak point and a bottom point). Two are shown).
The peak value refers to the highest diffusion angle value in one cycle of the diffusion angle distribution, and the bottom value refers to the lowest diffusion angle value in one cycle of the diffusion angle distribution.
In the diffusion sheet of the embodiment, in such a diffusion angle distribution diagram, the arithmetic average value of the peak value and the bottom value indicated by the adjacent peak point and the bottom point is between the adjacent peak point and the bottom point. It is preferably larger than the arithmetic average value of the diffusion angles at all points distributed in the range.
The “all points” described here mean all the measurement points.

The change in the diffusion angle is the arithmetic average value of the diffusion angle at all points where the arithmetic average value of the peak value and the bottom value indicated by the adjacent peak point and the bottom point is distributed between the adjacent peak point and the bottom point. If it is larger, it does not have to be strictly linear, curved, or stepped, but may vary from linear, curved, stepped, or a mixture of straight and curved due to variations in measurement of diffusion angle, etc. There may be.
When transitioning from the region directly above the light source on the diffusion sheet to the region between the light sources, the light incident angle with respect to that position increases linearly.

Considering that the intensity of light reflected downward from the diffusion sheet (that is, the light source side) and light transmitted in an oblique direction with respect to the normal direction of the diffusion sheet increases as the incident light angle increases. The amount of light to be diffused is not linear as it transitions from the region directly above the light source to the region between the light sources, and it is preferable that the amount of light attenuate more than that.
That is, the diffusion sheet in which the arithmetic average value of the peak value and the bottom value indicated by the adjacent peak point and the bottom point is larger than the arithmetic average value of the diffusion angles at all points distributed between the adjacent peak point and the bottom point. If so, it is possible to reduce luminance unevenness in accordance with attenuation of light to be diffused.
61 (a) to 61 (f), the horizontal axis is the relative position on the surface of the diffusion sheet, and the vertical axis is the diffusion angle (FWHM). The diffusion angle is linear, curved, straight and curved. The example of the diffusion angle distribution figure of the diffusion sheet which has changed to the mixed shape is shown.

In general, it is preferable to arrange a region having a relatively high diffusion angle immediately above the light source, but when the diffusion angle is extremely high as a whole, the illuminance immediately above the light source A region having a relatively low diffusion angle in the diffusion sheet may be disposed in a region having a high value.
Moreover, it is preferable that the diffusion angle between each area | region changes smoothly.
In particular, it is preferable that there is a shape including a plurality of continuous peak values in the high diffusion angle region from the viewpoint of reducing luminance unevenness, and the shape is a straight line or a downwardly convex curve or a straight line and a downwardly convex curve. A mixed shape is preferred ( FIGS. 61 (d) and (f)). Such a pattern is particularly effective when the light source is a line light source.

Further, there is a bottom value of the diffusion angle, and the diffusion angle distribution in the low diffusion angle region including the bottom value is preferably a downwardly convex curved shape having the bottom value as a minimum value from the viewpoint of reducing luminance unevenness. ( FIG. 61 (a)-(d)).
FIG. 61C shows a first section in which the distribution of the diffusion angle includes the peak value and has an upward convex curve shape, and the distribution of the diffusion angle includes the bottom value and has a downward convex curve shape. Such a pattern is particularly effective when the light source is a point light source. For example, when an LED (light emitting diode) is used as the point light source, the diffusion angle in the diffusion sheet of the embodiment can be designed with respect to the illuminance distribution regardless of the light emission angle. Specifically, assuming that the illuminance is distributed in a relative numerical step, there is a case where the diffusion angle is designed corresponding to the numerical value.

Here, the “high diffusion angle region” is an angle region larger than the arithmetic average value of the maximum value of the peak value and the minimum value of the bottom value, and the “low diffusion angle region” is the maximum value and the bottom value of the peak value. The angle region is smaller than the arithmetic average value of the minimum value of.
The arithmetic average value of the peak value and the bottom value is calculated using a distribution of diffusion angles based on the above definition.
In one cycle, the peak value and the bottom value are not limited to one, and a plurality of the same values may exist.
Further, the diffusion angle at all points distributed between adjacent peak points and bottom points refers to the diffusion angle existing in the broken line section of FIG .
That is, when there are a plurality of peak points, it means the diffusion angle existing at all points in the section between the position corresponding to the adjacent bottom point and the position corresponding to the peak point.

Figure 62 through Figure 64 are views showing an example of arrangement of the high diffusion angle region and a low diffusion angle region of the diffusion sheet embodiment.
62 and 63 , the high diffusion angle region B301 and the low diffusion angle region B302 are periodically present in the x-axis direction within the diffusion sheet surface, that is, the diffusion angles are as shown in FIGS. It shows that it changes periodically as shown in f).
The patterns shown in FIGS. 62 and 63 are preferably used for a line light source, but may be used for a point light source.

FIG. 64 is a diagram in which a high diffusion angle region B303 and a low diffusion angle region B304 periodically exist in the x-axis direction and the y-axis direction in the sheet surface.
This is also, in the x-axis or y-axis direction of the cross-section of the diffusion sheet, the diffusion angle as shown in FIG. 61 (a) ~ (f) have remained.
The pattern as shown in FIG. 64 is preferably used for a point light source, but may be used for a line light source.

A diffusion sheet having a concavo-convex structure on the surface and whose diffusion angle varies depending on the position on the surface can be produced as follows.
First, a sub-master mold in which a speckle pattern is formed so that a diffusion angle changes depending on a position by irradiating a photosensitive material or a photoresist with a laser beam through a lens or a mask in advance by interference exposure.
It is possible to control the range of the diffusion angle by changing the distance and size between the members constituting the laser irradiation system and adjusting the size, shape and direction of the speckle pattern, and record the uneven structure with different diffusion angles. it can.

The range of the diffusion angle is formed and controlled by the concavo-convex structure, and generally depends on the average size and shape of the speckle.
If speckle is small, the angle range is wide.
Moreover, the unit structure of the unevenness is not limited to an isotropic one, and an anisotropic one can be formed, or an uneven structure in which both are combined can be formed.
If the speckle is an oval in the horizontal direction, the shape of the angular distribution is an oval in the vertical direction.
In this way, a sub-master type in which the diffusion angle changes depending on the position is manufactured.
A metal is deposited on the sub-master mold by a method such as electroforming, and a speckle pattern is transferred to the metal to produce a master mold.
The speckle pattern is transferred to the resin layer by shaping the uncured resin layer made of the above-described photopolymerizable resin composition with ultraviolet rays using the master mold.
A detailed manufacturing method of this diffusion sheet in which the diffusion angle is changed depending on the position is disclosed in JP-T-2003-525472 (International Publication No. 01/065469).
Specifically, a light source, a mask provided with an aperture of variable size and shape provided in the optical path of light projected from the light source, a plate for recording a diffusion pattern generated by the light projected from the light source, Using a diffuser plate that diffuses light disposed between the mask and the plate, and a blocker provided between the diffuser plate and the plate to block part of the light, the size and shape of the mask opening and blocker, It is produced by changing the diffusion degree of the diffusion plate and the distance between the constituent members.

For example, the following method is mentioned.
(1) By making the opening shape of the mask vertically long, the shape of the bottom surface of the convex portion recorded on the plate is made into a horizontally long ellipse and exhibits a vertically long elliptical diffusing ability (diffusing angles in two orthogonal directions are different). Form a region.
(2) By making the opening shape of the mask square, the shape of the bottom surface of the convex portion recorded on the plate is isotropic, and isotropic diffusion ability (the diffusion angle is the same in all directions) Form.
When the periodic patterns are formed by combining the patterns (1) and (2), the diffusion sheet of the embodiment, that is, the diffusion sheet whose diffusion angle periodically changes in the plane can be manufactured.

The uneven height of the surface structure of the diffusion sheet can be determined from the pitch, aspect ratio, surface roughness, etc. of the cross-sectional shape of the diffusion sheet observed with a scanning electron microscope, for example.
Further, the pitch, aspect ratio, surface roughness, and the like can also be read from an observation image of the diffusion sheet surface by a laser confocal microscope.
For example, as the pitch is shorter, the aspect ratio is larger, or the surface roughness is larger, it can be considered that the unevenness height is higher.

[Light source unit]
The light source unit of the embodiment includes two or more light sources and the above-described diffusion sheet disposed to face the light sources.
FIGS. 65 (a), (b), 66 (a), and (b) are schematic configuration diagrams of the light source unit of the embodiment.
The light source unit of the embodiment uses a plurality of light sources. As the light source, a linear light source B11 such as a cold cathode tube (CCFL) as shown in FIG. 65 , an LED (light emitting diode) as shown in FIG. A point light source B12 such as a laser can be used.
In this case, the light sources B11 and 12 are arranged directly below the light incident surface and the light outgoing surface of the diffusion sheet B15.
The light source unit basically includes a light source (a linear light source B11 or a point light source B12) and a diffusion sheet B15 according to the embodiment disposed to face the light sources B11 and 12 (see FIG. 65 (a), see FIG. 66 (a)).
Moreover, it is preferable that a reflection sheet B13 having a function of reflecting light is disposed on the back side of the line light source B11 and the point light source B12, that is, on the side opposite to the diffusion sheet arrangement side.

Further, if the optical unit has the above-described configuration, a predetermined optical sheet, a diffusion plate containing a diffusing agent (reference numeral 14 in common) and the like may be further disposed. For example, the light source B11 , 12 and the diffusion sheet B15, a diffusion plate or a predetermined optical sheet B14 may be provided ( FIGS. 65 (b) and 66 (b)).
As the diffusing plate B14, a conventionally known one can be used as long as it has a function of diffusing light. For example, polystyrene, acrylic resin, polycarbonate, cycloolefin polymer, or the like added with an organic polymer or inorganic fine particles having an effect of diffusing light can be used. These diffusers have the effect of diffusing light and making the light from the lower light source uniform. Moreover, the uneven | corrugated shape may be formed in the said diffusion plate on the surface.
A diffusion plate in which two or more components are mixed and stretched to form a sheet can also be used.

As the reflection sheet B13, a conventionally known material can be used as long as it has a function of reflecting light.
For example, a resin such as polyester or polycarbonate is foamed and fine air particles are put inside to form a sheet, a sheet formed by mixing two or more resins, and a resin layer with a different refractive index is laminated. Any of the sheets can be used.
In addition, the reflective sheet B13 may have an uneven shape on the surface.
As these, those having inorganic fine particles added to the surface can be used as necessary.

In the light source unit of the embodiment, when a diffusion sheet whose diffusion angle periodically changes along a predetermined direction in the above-described plane is used, the period of the diffusion angle distribution of the diffusion sheet and the light incident surface of the diffusion sheet It is preferable that the period of the illuminance distribution at is substantially equal.
As described above, the period of the diffusion angle distribution controls the distance, size, speckle pattern, shape, and direction between the members constituting the laser irradiation system when recording the uneven structure on the surface in the manufacturing process of the diffusion sheet. Can be adjusted.
The illuminance distribution on the light incident surface of the diffusion sheet B15 can be measured by, for example, EZCONTRASTXL88 manufactured by ELDIM. Specifically, in the light source unit provided with the diffusion sheet B15, the omnidirectional luminance distribution is measured by setting the focal point of the apparatus at the position where the light incident surface of the diffusion sheet is located, excluding the diffusion sheet, and integrating from the result Measurement is performed by repeating the process of obtaining an integrated intensity in the in-plane measurement target range.
Figure 67 (a), (b) is a specific example of the configuration of a light source unit of the embodiment, a schematic perspective view.
67 (a) and 67 (b), in the diffusion sheet B15, the diffusion angle is periodically distributed in the plane, and the direction in which the diffusion angles are periodically distributed and the CCFL light source B11 It arrange | positions so that the direction orthogonal to a longitudinal direction may correspond.
Incidentally, FIG. 67 (b) is, in the configuration of FIG. 67 (a), has a configuration obtained by adding a predetermined optical sheet B14.

FIG. 68 is a diagram showing the relationship between the relative position of the light source and the diffusion angle distribution period of the diffusion sheet in the light source unit.
67 (a) and (b), since the period of the illuminance distribution on the light incident surface of the diffusion sheet is equal to the interval between the light sources, the diffusion angle distribution period in the diffusion sheet surface is made approximately equal to the light source interval. Thus, the period of the illuminance distribution can be made substantially equal to the period of the diffusion angle distribution described above.
In the illuminance distribution on the light incident surface of the diffusion sheet, when the illuminance in the region directly above the light source is high, it is preferable to dispose a high diffusion angle region of the diffusion sheet from the viewpoint of eliminating luminance unevenness.
FIG. 68 shows an example of the diffusion angle distribution designed to correspond to the illuminance distribution on the light incident surface of the diffusion sheet.
Further, the difference in diffusion angle, uneven height in the projection area between the light source B11, 12 and the projection area between the light sources B11, 12 and how the diffusion angle / concave height changes depending on the position in the diffusion sheet surface, In order to make the luminance uniform, it can be appropriately adjusted.

Hereinafter, a specific configuration example of the light source unit of the embodiment will be described.
For example, a configuration of the light source unit, it is possible to adopt the arrangement configuration shown in FIG. 69 (a) ~ FIG 69 (c).
In these, CCFL which is line light source B11 is illustrated as a light source, but the light source may be a point light source B12 such as an LED as shown in FIG. 70 , for example.

FIG. 69 (a) shows a configuration of the light source unit shown in FIG. 65 (b) described above, between the diffusion plate B14 disposed immediately above the light source B11 and the diffusion sheet B15 with reference to the vertical direction in the drawing. 1 shows a light source unit in which a surface-shaped diffusion sheet B16 having a fine concavo-convex structure formed thereon is disposed, and the surface-shaped diffusion sheet B16 is disposed immediately above the diffusion sheet B15. Here, as the surface-shaped diffusion sheet B16, a sheet in which spherical beads made of an acrylic resin are coated on a sheet of polyester resin, triacetyl cellulose, polycarbonate, or the like can be used.
Further, as the surface-shaped diffusion sheet B16, a sheet in which a fine concavo-convex structure by an ultraviolet curable resin is transferred onto a sheet of polyester resin, triacetyl cellulose, polycarbonate, or the like can be used.
Such a surface shaping type diffusion sheet B16 has a function of condensing the light diffused by the diffusion plate B14, together with the effect of diffusing and uniformizing the light. By using these surface-shaped diffusion sheet B16 and diffusion sheet B15 in combination, luminance unevenness can be reduced, and the light source unit can be made thinner and the number of light sources can be reduced.

FIG. 69B shows an array of prism arrangement structures above the diffusion plate B14 and the diffusion sheet B15 arranged immediately above the light source B11 in the configuration shown in FIG. 65B with reference to the vertical direction in the drawing. 1 shows a light source unit in which an optical sheet (hereinafter also referred to as “prism sheet”) 17 having a surface and a surface-shaped diffusion sheet B16 having the fine uneven structure formed on the surface are arranged in this order. .
FIG. 69 (c) shows a fine concavo-convex structure in the configuration shown in FIG. 65 (b) above the diffusion plate B14 and the diffusion sheet B15 disposed immediately above the light source B11 with reference to the vertical direction in the drawing. Shows a light source unit in which a surface-shaped diffusion sheet B16 formed on the surface and a reflective polarizing sheet B18 are arranged.
As the prism sheet B17, it is possible to use an optical sheet in which prism rows having a substantially triangular shape, a substantially trapezoidal shape, and a substantially elliptical shape are arranged in an array on the surface.
A shape obtained by rounding the apex of the cross-sectional shape can be preferably used from the viewpoint of improving scratch resistance. These prism sheets B17 can be used in a form in which a prism array made of an ultraviolet curable resin is transferred onto a base material sheet such as polyester resin, triacetyl cellulose, or polycarbonate. Since such a prism sheet B17 exhibits retroreflectivity, it has a function of collecting incident light to the front. By using this prism sheet in combination with the diffusion sheet of the embodiment, it is possible to reduce luminance unevenness, reduce the thickness of the light source unit, and reduce the number of light sources.

FIG. 70 (a) shows a surface having a fine concavo-convex structure above the diffusion plate B14 and the diffusion sheet B15 arranged immediately above the light source B12 with reference to the vertical direction in the drawing in the configuration shown in FIG. 66 (b) . 2 shows a light source unit in which two surface-shaped diffusion sheets B16 formed in the above are arranged and a reflective polarizing sheet B18 is arranged in this order.
FIG . 70B shows a configuration shown in FIG. 66B in which a prism sheet B17 is arranged above the diffusion plate B14 and the diffusion sheet B15 arranged just above the light source B12 with reference to the vertical direction in the drawing. Further, a light source unit in which a reflective polarizing sheet B18 is arranged in this order is shown.
As the reflective polarizing sheet B18, a sheet having a function of separating linearly polarized light from natural light or polarized light can be used.
As a sheet | seat which isolate | separates the said linearly polarized light, the film etc. which permeate | transmit one of the linearly polarized light orthogonal to an axial direction, and reflect the other are mentioned, for example.
Specifically, as the reflective polarizing sheet B18, a resin (polycarbonate, acrylic resin, polyester resin, etc.) having a large birefringence retardation and a resin (cycloolefin polymer, etc.) having a small birefringence retardation are alternately used. A sheet obtained by laminating and uniaxially stretching, a sheet having a structure in which several hundred layers of birefringent polyester resin are laminated (trade name DBEF, manufactured by 3M Co., Ltd.), and the like can be used.

In addition, as the configuration of the light source unit, for example, the arrangement configuration shown in FIGS . 71 and 72 can be adopted. In the following, the arrangement configuration is shown with reference to the vertical direction in the drawing, as in the example described above.
FIG. 71A shows a structure shown in FIG. 65A, in which a diffusion plate B14 is disposed between the light source B11 and the diffusion sheet B15, and a surface-shaped diffusion sheet B16 is disposed immediately above the diffusion sheet B15. A light source unit is shown.
FIG. 71 (b) shows a light source unit in which the diffusion plate B14 and the surface-shaped diffusion sheet B16 are arranged in this order above the diffusion sheet B15 in the configuration shown in FIG. 65 (a).
FIG. 71 (c) shows a structure shown in FIG. 65 (a), in which a diffusion plate B14 is disposed between the light source B11 and the diffusion sheet B15, and further above the diffusion sheet B15, a prism sheet B17 and a reflective polarizing sheet B18. The light source units arranged in this order are shown.
FIG. 71D shows a configuration in which the diffusion plate B14 is arranged between the light source B11 and the diffusion sheet B15 in the configuration shown in FIG. 65A, and the prism array direction of the prism sheet B17 is disposed above the diffusion sheet B15. A light source unit in which two sheets are arranged so as to be orthogonal to each other and a surface-shaped diffusion sheet B16 is further disposed thereon is shown.

FIG. 72A shows a structure shown in FIG. 65A, in which a diffusion plate B14 is disposed between the light source B11 and the diffusion sheet B15, and a surface-shaped diffusion sheet B16, a prism is disposed above the diffusion sheet B15. A light source unit in which a sheet B17 and a reflective polarizing sheet B18 are arranged in this order is shown. FIG. 72 (b) shows the structure shown in FIG. 65 (a) with a diffusion plate B14, a surface shaping type diffusion sheet B16, a prism sheet B17, and a reflection type polarizing sheet B18 above the diffusion sheet B15. The light source units arranged in order are shown.

[Liquid Crystal Display]
The liquid crystal display device according to the embodiment includes a predetermined display unit and the light source unit according to the embodiment described above.
For example, a liquid crystal display panel having a liquid crystal layer between two polarizing plates is provided above the light source unit of the embodiment as shown in FIG. 66 (b).

  The diffusion sheet and light source unit of the first invention of the specification have industrial applicability as a diffusion sheet and light source unit for liquid crystal display devices.

  Next, a description will be given of a second invention of the present specification relating to a light guide plate that can be suitably used in the present invention.

  The second specification relates to a light guide member, for example, a so-called edge light type surface light source device and a light guide plate that can be used in various illumination devices.

In the liquid crystal display device, since the liquid crystal display panel itself does not emit light, a surface light source device is required. As the surface light source device, two types are used: a direct type surface light source device in which the light source is installed on the back surface of the liquid crystal display panel, and an edge light type surface light source device in which the light source is installed on the side surface of the liquid crystal display panel. When importance is attached to thinning of a display device, an edge light type surface light source device suitable for thinning is often used.
Such an edge light type surface light source device generally includes a light guide plate that emits light from the light source to the liquid crystal display panel side, and an LED (light emitting diode) or CCFL (cold cathode) disposed on the side of the light guide plate. A light source such as a tube) and a prism sheet that directs light emitted from the light guide plate toward the liquid crystal display panel.
The light guide plate generally has a first surface (hereinafter also referred to as “light-emitting surface”), a second surface (hereinafter also referred to as “opposing surface”) facing the first surface, and the light-emitting surface facing the first surface. Light having at least one light incident surface sandwiched between surfaces, light that is incident from the side (light incident surface) is repeatedly reflected inside the plate and guided, and the light guided is provided on the opposing surface The light is emitted from the light emission surface to the liquid crystal display panel side by the emission mechanism.

By the way, when such a light guide plate is used in combination with a plurality of point light sources, a uniform brightness can be obtained at the center of the light exit surface (a part away from the point light source), but near the light entrance surface close to the point light source. In this area, the partial area directly facing the portion between the point light source and the point light source is dark, whereas an extremely bright so-called hot spot appears in the partial area directly facing the point light source, resulting in luminance unevenness. There are drawbacks.
Therefore, in the surface light source device using a plurality of point light sources as the light source, there is a problem that substantially only the center portion of the light exit surface of the light guide plate can be used.
As a method for preventing such luminance unevenness, an optical structure for diffusing incident light on the light incident surface (hereinafter also referred to as “diffusion structure”) has been studied.

  For example, Japanese Patent Laid-Open No. 2002-169034 discloses a light guide plate provided with a trapezoidal concavo-convex structure in which a symmetrical triangular shape is formed on a light incident surface. A light guide plate is disclosed in which a light-receiving surface is provided with a recess having a substantially square opening and an arcuate corner at the bottom.

  Furthermore, Japanese Patent Laid-Open No. 2006-49286 discloses a light guide plate in which a knurled cut is made on the opposing surface and a periodic fine cut such as a lenticular shape is made on the light incident surface. The gazette discloses a light guide plate in which an anisotropic light diffusing adhesive layer comprising an adhesive and a needle-like filler is provided on the light incident surface.

By the way, in a CRT display device that scans a phosphor surface with an electron gun and displays an image, each pixel on the image display surface emits light only for an instant for one frame, whereas in a liquid crystal display device, each pixel is lit by an illumination device. The light is emitted all the while. Therefore, in the liquid crystal display device, a decrease in contrast and blurring of moving images occur due to the afterglow characteristics of human eyes. As a countermeasure, the light exit surface portion of the light guide plate is divided into a plurality of parts, and only a part of the light exit surface portion of the light guide plate is caused to emit light by lighting only a part of the plurality of light sources. A technique for performing area control so as not to emit light, or a technique for adjusting the amount of light in each section (hereinafter referred to as “local dimming”) is known. In addition to improving the contrast of the display image described above, local dimming reduces power consumption and reduces the phenomenon (crosstalk) in which the right eye image and the left eye image can be seen simultaneously when displaying a 3D image. Is also a useful technique that can be used.
In the liquid crystal display device using the edge light type surface illumination device, in order to perform the above-mentioned local dimming, a plurality of light sources arranged in the vicinity of the light incident surface of the light guide plate are divided into two or more sections (for example, “upper half” ”And“ lower half ”), and only the necessary sections are lit. At this time, since the light emitted from the light source is diffusive, it is totally reflected between the light exit surface and the opposing surface in accordance with the critical angle of the material of the light guide plate in the sections other than the section where the light exit surface is desired to emit light. Since the light spreads in the range where the light source continues, there is a problem that the section adjacent to the section where the light source is turned on also emits light.
Thus, as one form for realizing local dimming, there has been proposed an illuminating device in which the light emitting area of the light exit surface is divided into a plurality of strip-shaped areas (see, for example, JP-A-2001-210122). Further, it is proposed to provide a convex part on the light incident surface of the light guide plate and arrange a light source on the top, and to arrange a lenticular lens on the light incident surface of the light guide plate and to arrange a light source at the focal position. (Japanese Patent Laid-Open No. 2009-199927).

The inventor of the second invention of the specification has sought to obtain an edge light type surface illumination device that achieves both suppression of hot spots and local dimming. However, if the technique described in Japanese Patent Laid-Open No. 2001-210122 described above is used to perform local dimming, the method is a method of dividing the light guide plate, and there is a concern about an increase in assembly man-hours and a decrease in strength. In addition, dark lines are generated in the divided portions. On the other hand, the technique described in Japanese Patent Application Laid-Open No. 2009-199927 provides an optical structure for condensing light on the incident surface portion, and what is an optical structure for diffusing light provided on the incident surface side to suppress hot spots. It is difficult to combine.
Therefore, the inventor of the specification 2nd invention provides a substantially parallel groove structure extending in the normal direction of the light incident surface on the light exit surface in order to perform local dimming, and on the light incident surface in order to eliminate hot spots. A light guide plate having a groove shape extending in the direction of the facing surface from the light exit surface was produced. However, a light guide plate having a diffusion structure on the light incident surface and a groove structure on the light output surface that is substantially parallel to the normal direction of the light incident surface contributes to the reduction of hot spots. The inventor of the second invention of the specification has found that a so-called bright line is generated in which a relatively high portion extends linearly (see FIG. 117 ).
The second invention of the specification has been made in view of the above points, and a light guide plate capable of local dimming with less luminance unevenness such as hot spots and bright lines in the vicinity of the light incident surface on the light exit surface, and the light guide plate. It is an object of the present invention to provide a surface light source device having an optical plate, a display device having the surface light source device, and a television receiver having the display device.

  As a result of intensive studies on the light guide plate, the inventors of the second invention of the specification can eliminate the above-described hot spots and bright lines by providing a light diffusion portion having controlled light diffusion characteristics on the light incident surface. The inventors have found that a uniform luminance distribution can be obtained over the entire light emitting surface, and have completed the second invention of the specification.

That is, the second invention of the specification is as follows.
[1]
At least one light incident surface for receiving light from the light source;
A first surface that is substantially orthogonal to the light incident surface and emits light incident from the light incident surface;
A light guide plate having a second surface substantially orthogonal to the light incident surface and facing the first surface,
The first surface and / or the second surface has a groove structure substantially parallel to the normal direction of the light incident surface,
The entire light incident surface has anisotropic light diffusion characteristics in which the diffusion angle of incident light from the normal direction in the longitudinal direction of the incident surface is greater than the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface. And
The light emission pattern curve of the entire light incident surface with the horizontal axis representing the emission angle of the light emitted from the normal direction of the light incident surface in the longitudinal direction of the light incident surface and the vertical axis representing the intensity appears in the light emission pattern curve. When compared with a normal distribution curve passing through a total of three points: one peak point where the intensity of the emitted light is the peak intensity and two intermediate points where the intensity of the emitted light is half of the peak intensity, the following conditions 1. And / or condition 2. A light guide plate that meets the requirements.
Condition 1. The range of the emission angle where the intensity of the emitted light is 3/4 or more of the peak intensity is narrower than the normal distribution curve.
Condition 2. The range of the emission angle where the intensity of the emitted light is 1/10 or more of the peak intensity is wider than the normal distribution curve.
[2]
The light guide plate according to [1], wherein a diffusion angle of light incident on the light incident surface from the normal direction in the longitudinal direction of the light incident surface is greater than 0 ° and less than 40 °.
[3]
The light guide plate according to [1] or [2], wherein a diffusion angle of light incident on the light incident surface from the normal direction in the longitudinal direction of the light incident surface is greater than 0 ° and not greater than 30 °.
[4]
The light incident surface is divided into two or more partial regions having different light diffusion characteristics;
The two or more types of partial regions are
A first partial region having an anisotropic light diffusion characteristic in which the diffusion angle of the incident light from the normal direction in the longitudinal direction of the incident surface is greater than the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface;
Anisotropy of incident light from the normal direction in the longitudinal direction of the incident surface is smaller than that of the first partial region and larger than the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface The second partial region having the above light diffusion characteristics and / or the diffusion angle of the incident light from the normal direction in the longitudinal direction of the incident surface and the diffusion angle in the direction perpendicular to the longitudinal direction of the incident surface are approximately A third partial region having equal isotropic light diffusion properties;
The light guide plate according to any one of the preceding items [1] to [3].
[5]
The light guide plate according to [4], wherein a ratio of at least one of the first to third partial regions per 20 square millimeters of the light incident surface is substantially constant in the surface.
[6]
[4] or [5] ].
[7]
The first to third partial regions are each divided into a plurality of small regions, and the area of at least one small region of the first to third partial regions is 0.2 to 4 square millimeters [4] ] To [6] The light guide plate according to any one of items.
[8]
Any one of [4] to [7] above, wherein the first partial region includes a plurality of concave portions or convex portions having an anisotropic shape in which an opening or a bottom surface is long in a direction substantially perpendicular to a light incident surface longitudinal direction. The light guide plate according to claim 1.
[9]
The light guide plate according to [8] above, wherein at least one of the pitch, depth, and height of the plurality of concave portions or convex portions is irregularly different.
[10]
The light guide plate according to [8] or [9], wherein an angle formed between a major axis direction of the plurality of concave portions or convex portions and a direction perpendicular to the longitudinal direction of the light incident surface is 10 ° or less.
[11]
The light guide plate according to any one of [8] to [10], wherein an average pitch of the plurality of concave portions or convex portions is 50 μm or less.
[12]
The light guide plate according to any one of [8] to [11], wherein an average depth or height of the plurality of concave portions or convex portions is 1 to 50 μm.
[13]
The light guide plate according to any one of [8] to [12], wherein the plurality of concave portions or convex portions are formed by speckle pattern exposure.
[14]
The light guide plate according to any one of [4] to [13], wherein a diffusion angle of light incident on the first partial region from the normal direction in the longitudinal direction of the light incident surface is 5 ° or more and less than 40 °. .
[15]
The light guide plate according to any one of [4] to [14] above, wherein a diffusion angle of light incident on the first partial region from the normal direction in the longitudinal direction of the light incident surface is not less than 0 ° and not more than 30 °. .
[16]
In the distribution with respect to the emission angle of the incident light intensity in the longitudinal direction of the incident surface and the direction perpendicular to the longitudinal direction of the incident surface of the light incident on the first partial region from the normal direction, the emission angle is 0 °. The light guide plate according to any one of [4] to [15] above, wherein the transmitted light intensity is 90% or more of the peak intensity.
[17]
The preceding items [4] to [16], wherein a diffusion angle of light incident on the second partial region or the third partial region from the normal direction in the longitudinal direction of the light incident surface is not less than 0 ° and less than 20 °. The light guide plate according to any one of the above.
[18]
In the distribution with respect to the emission angle of the incident light intensity in the longitudinal direction of the light incident surface of the light incident from the normal direction to the second partial region or the third partial region and the direction perpendicular to the longitudinal direction. The light guide plate according to any one of [4] to [17], wherein the emitted light intensity at an angle = 0 ° is 90% or more of the peak intensity.
[19]
An adhesive layer in which at least a part of the region having an anisotropic light diffusion characteristic existing on the light incident surface is laminated on the light incident surface, and an anisotropic light diffusion layer laminated on the adhesive layer are provided. The light guide plate according to any one of [1] to [18] above.
[20]
The light guide plate according to [19], wherein the adhesive layer is made of a material having a storage elastic modulus G ′ at 100 ° C. of 40,000 to 180,000 Pa.
[21]
The light guide plate according to any one of [1] to [20], wherein the groove structure has a lenticular lens shape.
[22]
The light guide plate according to any one of [1] to [20], wherein the groove structure includes a plurality of random grooves.
[23]
The light guide plate according to [22], wherein an average pitch of the plurality of random grooves is 30 μm or less.
[24]
The light guide plate according to [22] or [23] above, wherein an average depth of the plurality of random grooves is 1 to 50 μm.
[25]
The light guide plate according to any one of [1] to [24], wherein the groove structure is formed from a position 1 to 50 mm inside from the light incident surface side end of the first surface and / or the second surface.
[26]
The light guide plate according to any one of [1] to [25] above,
A plurality of point light sources arranged in the vicinity of the at least one light incident surface of the light guide plate;
A surface light source device.
[27]
A display panel having a display area for displaying light by adjusting light transmission;
The surface light source device according to the preceding item [26] disposed on the back surface of the display panel;
A display device.
[28]
The display device according to [27], wherein the display panel is a liquid crystal display panel.
[29]
The display device according to [27] or [28],
A tuner for receiving broadcast video signals;
A television receiver.

  When a light source comprising a plurality of point light sources is used by the light guide plate of the second invention, a surface light source device capable of local dimming with less luminance unevenness including hot spots and bright lines near the light incident surface on the light exit surface A display device including the surface light source device and a television receiver including the display device can be provided.

An embodiment of the light guide plate of the specification second invention will be specifically described below.
The light guide plate 2 according to the second invention has at least one light incident surface G22 that receives light from a light source, a first surface G21 that emits light incident from the light incident surface, and a first surface that faces the first surface. A groove structure having two surfaces, the first surface and the second surface being substantially orthogonal to the light incident surface, and the first surface and / or the second surface being substantially parallel to the normal direction of the light incident surface (See FIG. 111 ).

The light incident surface as a whole has a diffusion angle of outgoing light in the light incident surface longitudinal direction G24 (hereinafter also referred to as “first direction”) of incident light from the normal direction thereof. It is larger than the diffusion angle in the direction G25 perpendicular to the longitudinal direction (hereinafter also referred to as “second direction”).
Here, the longitudinal direction of the light incident surface refers to the direction of the long side of the circumscribed rectangle that minimizes the area circumscribed by the light incident surface.
In the light guide plate of the second specification of the invention, as shown in FIG. 110 , the emission angle of the incident light from the normal direction of the light incident surface in the first direction is the horizontal axis, and the intensity is the vertical axis. The light emission pattern curve of the entire light incident surface has a total of three points: one peak point where the intensity of the emitted light is the peak intensity and two intermediate points where the intensity of the emitted light is half the peak intensity. When compared with the normal distribution curve that passes, at least one of the following two conditions is satisfied.
Condition 1. 1. Conditions where the range of the emission angle where the intensity of the emitted light is 3/4 or more of the peak intensity is narrower than the normal distribution curve The range of the emission angle where the intensity of the emitted light is 1/10 or more of the peak intensity is wider than the normal distribution curve There is no limitation on the difference in the range of the emission angle, but the range of the emission angle where the intensity of the emitted light is 3/4 or more of the peak intensity Is preferably 3% or more narrower (smaller) than that of the normal distribution curve.
In addition, the range of the emission angle that is 1/10 or more of the peak intensity is preferably 5% or more (large), more preferably 10% or more, relative to that of the normal distribution curve.

The light emission pattern curve of the entire light incident surface is, for example, transmitted light of light incident on the surface from the normal direction of the light incident surface using a variable angle color difference meter such as GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. It can be obtained by measuring the angular distribution in the first direction of intensity (distribution of the intensity of transmitted light with respect to the emission angle). In addition, the laser diameter of the light source of the incident laser beam used in that case shall be 3 mm.
Here, when the light incident surface is divided into a plurality of partial regions having different light diffusivities as will be described later, the average value of the light emission pattern curve measured for 10 or more arbitrary points (output for each emission angle). The distribution of the average value of the incident light intensity) is defined as the light emission pattern curve of the entire light incident surface.

The diffusion angle in the first direction and the second direction of the entire light incident surface is not limited, but is preferably in the following range. Here, the “diffusion angle” refers to an angle (FWHM: Full Width Half Maximum) that is twice the angle (half-value angle) at which the outgoing light intensity is attenuated to half the peak intensity (see FIG. 110 ).
The diffusion angle in the first direction and the second direction is appropriately determined according to the arrangement of the point light sources used in combination when the light guide plate is used in the surface light source device and the type of other optical elements such as the diffusion sheet and the reflection sheet. In general, the diffusion angle in the first direction is preferably greater than 0 ° and less than 40 °, more preferably 5 ° or more and less than 25 °. Further, the diffusion angle in the second direction is preferably smaller than the diffusion angle in the first direction and more than 0 ° and less than 30 °, more preferably less than 15 °, and still more preferably 10 °. Is less than.

In addition, the diffusion angle of the entire light incident surface is, for example, Photo Inc. Using a variable angle color difference meter such as Photon manufactured by Nippon Steel and GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. described above, the angular distribution of the output light intensity of the light incident on the light incident surface from the normal direction of the light incident surface (output It can be determined by measuring the distribution of the intensity of the incident light with respect to the emission angle.
Here, when the light incident surface is divided into a plurality of partial regions having different light diffusivities as will be described later, the average value of the angular distributions of the emitted light intensity measured at 10 or more arbitrary points (each outgoing light The distribution of the average value of the outgoing light intensity with respect to the angle) is defined as the angular distribution of the outgoing light intensity over the entire light incident surface.

The light emission pattern curve as described above is obtained by, for example, dividing the light incident surface into two or more types of partial regions having different light diffusion characteristics, and at least one type of partial region (first partial region) is determined by the method. This can be realized by configuring the diffusion angle of the outgoing light in the first direction of the incident light from the linear direction to have anisotropic light diffusion characteristics larger than the diffusion angle in the second direction.
At this time, for example, as shown in FIG. 114 , the light incident surface is divided into two or more types of partial regions having different light diffusion characteristics, and at least one type of partial region is divided into a plurality of small regions. It can be preferably used.

  The two or more types of partial regions are at least a first portion having anisotropic light diffusion characteristics in which the diffusion angle in the first direction of incident light from the normal direction is larger than the diffusion angle in the second direction. And a second partial region having an anisotropic light diffusion characteristic in which the diffusion angle in the first direction of incident light from the normal direction is greater than the diffusion angle in the second direction, the first direction The diffusion angle of the incident light from the normal direction to the second partial region smaller than that of the first partial region and / or the diffusion angle in the second direction is substantially the same. And a third partial region having equal isotropic light diffusion characteristics.

  In addition, each light emission pattern curve of each of the first to third partial regions is the same as the condition 1. Alternatively, the condition 2. Is not necessarily satisfied, and may be represented by a normal distribution curve.

  In order to more effectively prevent luminance unevenness, it is preferable that the two or more types of partial regions are present in an appropriate ratio in the light incident surface.

Although there is no specific limitation on the ratio of the area occupied by each partial region in the light incident surface, at least one of the first to third partial regions is divided into a plurality of small regions, and the small regions are incident on the light incident surface. The ratio of the area per 20 square millimeters is preferably 10 to 80%, and the ratio of at least one of the first to third partial areas per 20 square millimeters of the incident surface is substantially constant throughout the surface. It is preferable.
Here, “substantially constant” means that when the proportion of the at least one partial region per 20 square millimeters is measured at any 10 or more locations on the light incident surface, the variance of the proportion is 10% of the average value. It means the following.

  Further, each of the first to third partial regions is divided into a plurality of small regions, and an area of at least one of the first to third partial regions is 0.2 to 4 square millimeters. Is preferred. By setting the area of the small area of each partial area sufficiently small, when using the light guide plate of the second invention of the specification as a surface light source device, the accuracy of alignment of the light source and the light guide plate is strict. No need to ask.

There is no limitation on the arrangement of the first partial region, the second partial region, and / or the third partial region on the light incident surface. For example, the respective partial regions may be regularly arranged ( FIGS. 114 (a) to (e)) or may be randomly arranged ( FIG. 114 (f)). Each partial region may be arranged so as to cross the light incident surface in the second direction ( FIGS. 114 (a) and (b)), or arranged in an island shape without crossing ( FIG. 114 (c). ) To (f)). Furthermore, it may be divided into three or more types of partial regions ( FIG. 114 (e)).

There is no limitation on the diffusion angle of light incident on each partial region from the normal direction, but it is preferable to be in the following range.
The diffusion angle in the first direction of the first partial region is preferably 5 ° or more and less than 40 °, more preferably 5 ° or more and less than 20 °. The diffusion angle in the second direction is preferably smaller than the diffusion angle in the first direction and greater than 0 ° and less than 40 °, more preferably less than 15 °.

  The diffusion angle in the first direction of the second partial region is smaller than that of the first partial region, and is preferably 0 ° or more and less than 20 °, more preferably less than 10 °. The diffusion angle in the second direction is smaller than the diffusion angle in the first direction of the second partial region, and is preferably 0 ° or more and less than 20 °, more preferably less than 10 °.

  The third partial region has substantially the same diffusion angle in the first direction and the second direction, and is preferably 0 ° or more and less than 20 °, more preferably less than 10 °. Here, “substantially equal” means that the ratio of both is in the range of 0.9 or more and less than 1.1. The diffusion angle in the first and / or second direction of the third partial region may be 0 °.

  In addition, the diffusion angle of each partial region is, for example, Photo Inc. Using a variable angle color difference meter such as Photon manufactured by Nippon Steel and GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. described above, the angular distribution of the outgoing light intensity of the light incident on each partial region from the normal direction of the light incident surface (output It can be determined by measuring the distribution of the intensity of the incident light with respect to the emission angle.

Also, if the size of each partial area is smaller than the laser diameter of the laser light source used for measurement, the diffusion angle of each partial area can be expressed when the angular distribution of the emitted light intensity of each partial area can be expressed as a normal distribution. Is obtained by approximating the angular distribution of transmitted light intensity of light incident on a surface where a plurality of partial areas intersect with each other as an addition of the angular distribution (normal distribution) of outgoing light intensity of each partial area. Is possible ( FIG. 115 ). The normal distribution curve is a curve represented by the following equation, where C is a constant and σ is a standard deviation.

By changing C and σ of each of the two normal distribution curves and determining each value so that the difference between the approximate value obtained by adding the intensities at each angle and the actual measurement value becomes small, the output of each partial region is obtained. An approximate normal distribution of the angular distribution of the incident light intensity is determined. For accurate approximation, the sum of the absolute values of the difference between the approximate value obtained for a total of 171 points and the actual measurement value at every emission angle from −85 ° to 85 ° is less than 150. It is preferable to obtain C and σ. When calculating approximate values, use the Microsoft MICROSOFT EXCEL (registered trademark) solver tool to calculate the C and σ of each of the two normal distribution curves so that the sum of the differences between the approximate values and the measured values is minimized. Changing is useful because C and σ of each normal distribution curve can be obtained in a short time. Further, the same function can be executed by various programming languages, but the method of obtaining the approximate value in the second invention of the specification is not limited to these. The FWHM of the two normal distributions obtained by the above method is defined as the diffusion angle of the first partial region and the second partial region or the third partial region.

In each of the first to third partial regions, the transmitted light intensity of the light at the emission angle = 0 ° is the peak intensity in the angular distribution of the emitted light intensity in the first and second directions of the light rays incident from the normal direction. It is preferable that it becomes 90% or more.
A specific example is shown in FIG . FIG. 116 is an angular distribution of the emitted light intensity in the first direction of the first partial region alone measured using a GC5000L manufactured by Nippon Denshoku Industries Co., Ltd.
In the figure, the intensity of the emitted light at the ◇ (outlined) portion is 90% or more of the peak intensity. In either angular distribution, the outgoing light intensity is 90% or more of the peak intensity at the outgoing angle = 0 °.
As described above, the light diffusion characteristics of the first to third partial regions have a plurality of angular distributions of the emitted light intensity of the emitted light in the first and second directions when a light ray is incident from the normal direction. It is preferable that it does not have a peak and changes gently.

  In the light guide plate according to the second aspect of the specification, it is sufficient that there is at least one light incident surface, and there may be two or more. When two light incident surfaces are provided, the shape of the light guide plate is preferably a flat rectangular parallelepiped having the first surface and the second surface as main surfaces, and the two light incident surfaces are opposed to each other. preferable. In this case, since two opposing light incident surfaces have the same length, there is a merit that the number and type of point light sources can be made the same and parts can be shared.

There is no limitation on the method of imparting anisotropic light diffusion characteristics to the light incident surface (partial region thereof) of the light guide plate of the second specification.
For example, a method of mixing an anisotropic diffusing agent or the like in a translucent film or pressure-sensitive adhesive so that the direction of the major axis is oriented in a specific direction and bonding them to the corresponding region of the light incident surface can be mentioned. It is done. Specifically, an acicular filler having a major axis of 10 to 300 μm and a minor axis of 0.3 to 5 μm, which is added with an acicular filler having a refractive index different from that of the adhesive, is applied while applying a shearing force. By processing, the direction of the major axis can be aligned along the coating direction, and anisotropic light diffusion characteristics can be imparted to the coated region (see JP 2008-34234 A).

In addition, it is also preferable to provide a plurality of concave portions or convex portions having an anisotropic shape in which the opening portion or the bottom surface is long in a specific direction in the region where the light incident surface has anisotropic light diffusion characteristics. The one specific direction is preferably a direction parallel to the second direction.
In addition, when the angle formed by the major axis of the opening (bottom) of the recess (projection) with a specific direction is 40 degrees or less (not 0 degree), the opening of the recess (projection) (Bottom) shall be “having a long anisotropic shape in one specific direction”, but the angle between the major axis of the opening (bottom) of the recess (convex) and the specific one direction is 10 degrees. Preferably, it is 8 degrees or less, more preferably 6 degrees or less, more preferably 4 degrees or less, and most preferably 0 degrees. Here, the major axis of the opening (bottom surface) refers to the long side of the circumscribed rectangle that minimizes the area circumscribing the opening (bottom surface).

  Other than the anisotropic shape where the shape of the opening (bottom surface) is mixed with the concave portion (convex portion) which is the shape of the anisotropic shape long in one specific direction, and the shape of the opening (bottom surface) is long in one specific direction Concave part (convex part) having a shape of (for example, the opening part (bottom surface) is an isotropic shape such as a circle, or the opening part (bottom surface) is an anisotropic shape, but the major axis has a specific direction. May not exist in parallel). However, in the region where the opening (bottom) of the recess (projection) having an anisotropic shape having an opening (bottom surface) long in a specific direction is provided, the recess (projection) having an anisotropic shape. It is preferable that the sum of the areas of the openings (bottom surface) exceeds the sum of the areas of the openings (bottom surface) of the other recesses (projections).

  The ratio of the major axis to the minor axis (major axis / minor axis) of the anisotropic shape is not limited, but is preferably 2 or more, more preferably 10 or more. Here, the minor axis and the major axis refer to the short side and the long side of the circumscribed rectangle having the smallest circumscribed area, respectively.

The anisotropic shape is not limited, and specific examples thereof include a straight line (groove) as shown in FIG. 111 and a substantially elliptical shape as shown in FIG.
The shape of the opening (bottom surface) of the concave portion (convex portion) can be determined by observing an arbitrary portion of the light incident surface with a microscope (such as a scanning electron microscope or a laser confocal microscope).

  The pitch in the first direction of the recesses (projections) is not limited, but the average pitch is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. The average pitch is preferably 580 nm (the central wavelength of visible light) or more, and more preferably 780 nm (the entire visible light region) or more.

  When the average pitch is set to such a value, a claw or the like is hardly caught on the concave portion or the convex portion at the time of handling, and handling properties are improved. Furthermore, since the light diffused by the light guide plate included in the surface light source device of the specification second invention is visible light (electromagnetic wave of 380 nm to 780 nm), it is average to sufficiently exhibit the diffusion effect by the concave portion or the convex portion. The pitch is preferably a value as described above.

Here, the pitch in the first direction of the concave portions (convex portions) is between adjacent valley bottoms (in the case of concave portions) or peaks (in the case of convex portions) in an arbitrary cross section parallel to the first direction of the light incident surface. This refers to the horizontal distance (the distance in the direction parallel to the light incident surface) (see FIG. 13). If the valley bottom (mountain peak) is flat, the pitch is determined with the center as the valley bottom (peak peak).
Further, the average pitch in the first direction of the concave portions or convex portions is a concave portion present in 100 μm arbitrarily extracted from an arbitrary vertical cross section parallel to the light exit surface of the region where the concave portion (convex portion) of the light incident surface is formed. It is set as the average value of the pitch of (convex part).
The (average) pitch in the first direction of the concave portion (convex portion) is determined by using an arbitrary cross section parallel to the first direction of the region where the concave portion (convex portion) of the light incident surface is formed. It can be determined by observing and measuring with a focusing microscope or the like.

There is no limitation on the size (depth / height) of each recess (projection).
For example, the minor axis of the opening (bottom surface) may be 580 nm to 50 μm, 780 nm to 20 μm, or 1 to 10 μm. Further, the major axis of the opening (bottom surface) may be, for example, 5 μm or more and 2 cm or less.
The depth (height) may be, for example, 500 nm to 50 μm, 700 nm to 30 μm, or 5 to 10 μm. The average depth (height) of the concave portion or convex portion is also preferably 500 nm to 50 μm, more preferably 700 nm to 30 μm, and further preferably 5 to 10 μm.

  Here, the depth (height) of the concave portion (convex portion) is the higher peak among the peaks on both sides constituting each concave portion in an arbitrary cross section of the region where the concave portion (convex portion) of the light incident surface is formed. Vertical distance (between the bottom of the lower valley and the top of the convex part of the valleys on both sides constituting each convex part) (the distance in the direction perpendicular to the light incident surface) ( This refers to the difference in elevation between the top of the mountain and the bottom of the valley (see FIG. 13). Moreover, the average depth (height) of the concave portion or the convex portion is that of the concave portion (convex portion) existing at 100 μm arbitrarily extracted from an arbitrary vertical cross section of the region where the concave portion (convex portion) of the light incident surface is formed. The average value of depth (height). The size of the concave portion (convex portion) can be determined by observing and measuring an arbitrary portion of the light incident surface with a microscope (such as a scanning electron microscope or a laser confocal microscope).

However, when the shape of the concave portion (convex portion) is a groove (ridge) parallel to the second direction, the length is preferably larger than the length of the light emitting surface of the point light source in the second direction. That is, the length of the groove (畝) is preferably equal to or larger than the size of the light emitting surface of the point light source. In FIG. 111 , the groove 23 has a length that crosses the light incident surface 22 in the second direction 25, but the length of the groove (畝) does not necessarily cross the light guide plate. Good.

It is preferable that at least one of the shape, size (depth, height) and pitch in the first direction of the plurality of concave portions (convex portions) is randomly (irregularly) different because the luminance unevenness reducing effect is improved. .
Here, the difference in size and pitch means that the value obtained by multiplying the standard deviation by 3 (3 sigma) exceeds 10% of the average value.

  There is no limitation on the method of forming a plurality of recesses or projections having an anisotropic shape having an opening or a bottom that is long in a specific direction on the light incident surface of the light guide plate of the second invention of the specification. The above-described methods ((1) to (3)) can be employed. Moreover, the same thing as what was mentioned above can be used also about the adhesive layer used in that case, and the resin layer which has a some recessed part or convex part on the surface.

[Light diffusion layer]
Next, the light diffusion layer will be described. The light diffusing layer is a layer that can be used to give anisotropic or isotropic light diffusing characteristics to the first to third partial regions of the light incident surface. A film having a concavo-convex structure in a method of forming a plurality of concave portions or convex portions on a light incident surface by laminating a film having a light guide plate using a translucent adhesive or the like, an anisotropic shape in the film This corresponds to a translucent film mixed with an anisotropic diffusing agent when a translucent film mixed with a diffusing agent is bonded to a light guide plate using an adhesive or the like.
The light diffusion layer may be a layer having a function of diffusing incident light anisotropically or isotropically, and a conventionally known layer can be used, and the material, shape, and the like are not limited.
The thickness of the light diffusion layer is not limited, but is preferably about 25 to 500 μm from the viewpoint of adhesiveness with the adhesive layer. If it is too thin, the stiffness will be insufficient, and the workability at the time of pasting on the substrate will be reduced. On the other hand, if it is too thick, the stiffness will be too strong and the workability of pasting will be reduced. It is more preferable that

The light diffusing layer may be a layer having a concavo-convex structure on its surface, like the film having a concavo-convex structure in the method (3) described above, and further, on the surface laminated on the transparent base film layer. You may have a multilayer structure containing the transparent resin layer which has an uneven structure.
In this case, the material of the light diffusion layer or the transparent resin layer having a concavo-convex structure on the surface is not limited, and examples thereof include a cured product of a photopolymerizable resin composition.
The material and thickness of the transparent base film layer are not limited, and examples of the material include highly transparent materials such as polyethylene terephthalate, polycarbonate, and polystyrene (for example, the total light transmittance is 90% or more, and the haze is 1). 0.0 or less), and the thickness can be, for example, 20 to 250 μm, more preferably 50 to 125 μm.

  As the photopolymerizable resin composition, the same photopolymerizable resin composition as that described above for the present invention and the first invention of the specification can be used.

[Light scattering processing of facing surface]
In the second surface of the light guide plate of the specification second invention, in order to make the light distribution on the first surface uniform, a light scattering process having a gradation that becomes dense toward the direction away from the light incident surface is formed. Can do. In the case of a surface light source device for a display device, it is preferable that a uniform mountain-shaped light emission distribution with the highest luminance at the center of the screen is easy to visually recognize while improving the uniformity of the light emission distribution. The density of the light scattering process at the central portion of the second surface may be increased.

  Examples of light scattering processing having gradation that becomes denser in the direction away from the light incident surface include, for example, a layered (printed) part of reflective or diffusive material or a part formed with uneven shapes (hereinafter collectively referred to as “dots”). ))) With a gradation pattern that gradually increases in area as it moves away from the incident surface (in the case of printing, it may be a gradation pattern that gradually becomes darker) The gradation pattern provided so that a pitch may become narrow as it leaves | separates from a surface is mentioned. Examples of the shape of the dots in this case include a circle and a quadrangle, and the size can be, for example, about 0.1 to 2.0 mm.

When the light scattering process as described above is provided on the second surface of the light guide plate of the specification second invention, in order to further reduce the luminance unevenness, as shown in FIG. It is preferable not to form dots at the facing positions, or to reduce the dot density or to make each dot small (thin). By doing so, luminance unevenness can be further reduced, so that P / G described later can be further increased.

[Groove structure of first surface and / or second surface]
The light guide plate of the second invention of the specification has a groove structure substantially parallel to the normal direction of the light incident surface on the first surface and / or the second surface. The groove structure is preferably a lenticular lens shape or a plurality of random grooves. Whether the groove structure is provided on the first surface or the second surface may be appropriately determined in consideration of ease of manufacturing, ease of handling, and the like. Although it may be provided on both the first surface and the second surface, for example, when the light scattering process as described above is provided on the second surface, it is preferably provided only on the first surface.
Furthermore, from the viewpoint that the hot spots near the light incident part can be reduced, the groove structure starts from a position 1 to 50 mm inside from the light incident surface side end of the first surface and / or the second surface. It is preferable to provide it so that it may extend in the opposite direction.

The lenticular lens shape preferably extends in a direction substantially parallel to the normal direction of the light incident surface and is provided in parallel. The pitch of the lenticular lens shape is preferably 20 to 500 μm, and the depth is preferably 20 to 500 μm (see FIG. 118 ). If the pitch is too small, accurate processing of the lenticular lens is difficult, and if the pitch is too large, moire between the pixels of the liquid crystal panel is likely to occur. If the depth is too shallow, the straightness of light decreases, and if the depth is too deep, accurate machining becomes difficult or easily damaged.

Next, a plurality of random grooves will be described.
That the plurality of grooves are random means that at least one of the cross-sectional shape, pitch, and depth of the plurality of grooves is randomly (irregularly) different.
FIG. 118 shows an example in which a plurality of random grooves substantially parallel to the normal direction of the light incident surface are provided on the first surface.

There is no limitation in the cross-sectional shape of each groove | channel, For example, it can be set as V shape or U shape.
The pitch of the grooves refers to a horizontal distance between the valley bottoms of adjacent grooves (a horizontal distance in a direction parallel to a surface having a plurality of random grooves). When the valley bottom is flat, the pitch is determined with the center as the valley bottom. The cross-sectional shape and width of the groove may change along the extending direction of the groove. The depth of the groove is the vertical distance between the peak of the higher peak of the peaks on both sides of each groove and the valley bottom of the groove (distance in the direction perpendicular to the surface having a plurality of random grooves). (Elevation difference between mountain top and valley bottom).
The depth of the groove may change gently or steeply along the extending direction, and as a result, there may be a portion where the groove is interrupted, but it is preferable that it does not change if possible.
Specific examples of a plurality of random grooves preferably used in the second invention of the specification are shown in FIGS. 120A and 120B. FIG. 120A shows a specific example of a plurality of random grooves having anisotropic light diffusion characteristics in which a diffusion angle in a direction perpendicular to the groove (described later) is 30 degrees and a diffusion angle in a direction horizontal to the groove is 1 degree. It is a surface profile figure which shows an example. FIG. 120B shows a specific example of a plurality of random grooves having anisotropic light diffusion characteristics in which the diffusion angle in the direction perpendicular to the grooves is 60 degrees and the diffusion angle in the direction horizontal to the grooves is 1 degree. It is a surface profile figure.

The average pitch of a plurality of random grooves is not limited, but is preferably 30 μm or less, more preferably 20 μm or less, still more preferably 15 μm or less, and particularly preferably 10 μm or less. The average pitch of the plurality of random grooves is preferably 580 nm (the central wavelength of visible light) or more, more preferably 780 nm (the entire visible light region) or more.
Since the pixel pitch of the display panel used in combination with the light guide plate and the structure pitch of the optical sheet are approximately 100 to 600 μm and 50 to 150 μm, respectively, the average pitch of a plurality of random grooves is set to such a value. If set, generation of moire due to spatial interference with a display panel or an optical sheet used in combination with the light guide plate can be prevented. Furthermore, if the average pitch is set to such a value, the claw and the like are not easily caught in the groove during handling, and handling is improved. Furthermore, since the light guided by the light guide plate of the specification second invention is visible light (electromagnetic wave of 380 nm to 780 nm), in order to sufficiently exhibit the effect of direct evolution of light by a plurality of random grooves. The lower limit value of the average pitch is preferably a value as described above.
The average depth of the plurality of random grooves is not limited, but is preferably 1 to 50 μm, more preferably 5 to 10 μm.

The slope angle of the groove has a great influence on the straightness of light. That is, when a groove structure is provided on the first surface or the second surface, light that spreads outside is reflected by the slope of the groove in the light guide plate and returned to the light guide plate to improve the straightness of the light. it is conceivable that. Therefore, the slope angle of each groove is preferably 40 to 60 degrees. Therefore, it is preferable that the plurality of random grooves provided on the first surface or the second surface account for 5% or more of the groove angle within the range of 40 degrees to 60 degrees. More preferably, it is 10% or more. Of these, the greater the proportion occupied by 45 ± 5 degrees contributes to the improvement in straightness.
Here, the “slope angle” is a general term for an angle formed by a surface tangent to each groove and a surface having a groove structure in a cross section perpendicular to the groove of a surface having a plurality of random grooves.
And about the ratio which a slope angle has in the range of 40 degree-60 degree | times, the arbitrary perpendicular | vertical of the surface which has a random several groove | channel by microscope observation (a scanning electron microscope, a laser confocal microscope, etc.) A range with a distance of 300 μm is extracted arbitrarily from the cross section (cross section perpendicular to the groove structure), and tangents with points at 0.5 μm points from the end of the range are extracted. It is determined by measuring an angle (acute angle) formed by the surface having the groove.

The light guide plate of the second invention of the specification can be incorporated into a surface light source device and used for various display devices such as a notebook PC, a portable information terminal, a desktop PC monitor, a digital camera, and a television receiver.
In particular, the surface light source device incorporating the light guide plate of the second invention of the specification uses a plurality of point light sources as the light source, and has less luminance unevenness (hot spots / bright lines) in the vicinity of the light incident surface and is uniform over the entire light exit surface. Therefore, it is suitable for use in a liquid crystal display device because a large and thin liquid crystal display device can be provided at low cost and / or in a narrow frame.
The specific modes of the surface light source device, the display device, and the television receiver incorporating the light guide plate of the second invention of the specification may be the same as those of the surface light source device, the display device, and the television receiver of the present invention. it can.

  Next, in the present invention, also as a light guide plate (or a layer having a plurality of concave portions or convex portions having an anisotropic shape whose opening or bottom surface is long in one direction, which is bonded to the light incident surface of the light guide plate). The third invention of the present specification relating to a suitably usable diffusion sheet will be described.

  The third invention of the specification relates to a sheet that diffuses light from a light source, and more particularly to a diffusion sheet that diffuses only in one direction and hardly diffuses in a direction orthogonal to a certain direction.

  Currently, various lighting fixtures using light emitting diodes (LEDs) have been developed and sold. However, since the LED is a point light source with strong directivity, there is a drawback that a large number of LEDs are required to irradiate a wide area. Then, the technique regarding the diffusion plate and diffusion sheet for installing between a light source and irradiation object is examined.

  For example, Japanese Patent No. 3413519 discloses a light homogenizing device that forms a fine engraving surface texture on a photosensitive medium by exposing the photosensitive medium with irregular non-planar speckles.

  In Japanese Patent Publication No. 2004-508585, a desired speckle pattern is realized by appropriately selecting various lens combinations, aperture dimensions, and distances of respective members used for exposure, and exposure is performed on a photosensitive medium. Thus, a method for producing a master for an anisotropic diffuser is disclosed. Also, final masters having output angles of 100 ° x90 °, 60 ° x40 °, 50 ° x10 °, 20 ° x1 °, 6 ° x0.3 °, 60 ° x0.5 °, 130 ° x70 ° are produced. An embodiment to that effect has been disclosed. The notation “A ° × B °” means that the diffusion angle in the direction in which the diffusion angle is maximum is A ° and the diffusion angle in the direction in which the diffusion angle is minimum in the diffuser manufactured using the master. It means that the value is B °.

  Japanese Patent Laid-Open No. 2005-24886 discloses that only light incident from a specific direction is scattered, light incident from a direction other than the specific direction is transmitted, and scattered light intensity of light incident from the specific direction is transmitted. A projection-type image display device is disclosed in which anisotropic scattering films having different half-value widths on two scattering surfaces are arranged on the front surface as a screen. A holographic method has been disclosed as a method for producing such a film. The screen has a vertical diffusion angle of 32 °, a horizontal diffusion angle of 75 °, and a vertical diffusion angle of the screen of 42 °. An embodiment with a directional diffusion angle of 103 ° is disclosed.

  Japanese Patent Application Laid-Open No. 2006-337906 discloses a light diffusion film having an anisotropic diffusion angle. As a method for producing such a light diffusing film, a method of sandblasting in a state where a blast gun is laid on a mold base material is disclosed. Further, a mold having an average unevenness interval of 0.13 mm in the X-axis direction and 0.07 mm in the Y-axis direction is produced, a light diffusion film is produced using the mold, and a vertical direction is produced using the light diffusion film. An example in which an anisotropic screen having a diffusion angle of 32 ° and a horizontal diffusion angle of 51 ° is produced is disclosed.

  In order to realize a line illumination system such as a line illumination for inspection in a factory by using a plurality of point light sources such as LEDs, the point light sources are arranged in a line and light is arranged in a line by the diffusion sheet. (Hereinafter referred to as “horizontal direction”).

  In the diffusion sheet, the low horizontal diffusibility corresponds to a portion corresponding to a vertical foot from the point light source and a vertical foot from an intermediate point between the adjacent point light sources on the irradiated surface. This is not preferable because unevenness in brightness and darkness is generated between the portion and the portion to be performed. Although it is conceivable to reduce the unevenness of light and darkness by increasing the number of point light sources and reducing the intervals, there is a tendency to increase power consumption and manufacturing cost.

  Further, the diffusion sheet has a high diffusivity in a direction orthogonal to the direction in which the point light sources are arranged (hereinafter referred to as “vertical direction”). Since the intensity of the light applied to the portion corresponding to the perpendicular foot from the point light source is lowered, it is not preferable as a line illumination system.

  In addition, when the line of the said linear illumination system is short, you may diffuse the light to a specific direction with the said diffusion sheet by using the said point light source as one. Also in this case, it is preferable that the light diffusibility is high in the specific direction and the light diffusivity in the direction orthogonal to the specific direction is low, as in the case where there are a plurality of point light sources.

  Therefore, a diffusion sheet that diffuses light from a point light source in the horizontal direction and does not diffuse in the vertical direction is preferable. As a means for expanding the light from the point light source only in one direction as described above, a regular surface structure such as a lens array is known. However, when a regular surface structure is used, for example, the irradiated light is changed. Moire interference fringes may occur when taking an image. For this reason, the image quality may be impaired, which is not preferable.

  Therefore, the third invention of the specification is that in a line illumination system using a point light source, even when the number of point light sources is reduced and the interval is widened, the uniformity of light on the irradiated surface is high and the light on the irradiated surface is It is an object of the present invention to provide a diffusion sheet that can suppress a decrease in the intensity of light and does not generate moire interference fringes, and a lighting device having the diffusion sheet.

  The inventors of the third invention of the specification have made extensive studies in order to achieve the above object, and as a result, the interference light diffused through the holographic diffuser having a minimum value of the diffusion angle of the emitted light of 0.1 degrees or less. A diffusion sheet produced by transferring from a sub-master mold obtained by exposing and developing a photosensitive medium with a speckle pattern obtained by diffusing light in only one direction and orthogonal to a certain direction The inventors have found that almost no diffusion occurs in the direction, and have completed the third invention of the specification.

That is, the third invention of the specification is as follows.
[1]
There is a non-periodic surface uneven structure on at least one surface, and there are a direction in which the diffusion angle of outgoing light of the light incident on the surface uneven structure from the normal direction has a maximum value and a direction in which the minimum value is present. A diffusion sheet wherein the ratio of the maximum value to the minimum value is 200 or more, the maximum value is 40 degrees or more and less than 100 degrees, and the minimum value is less than 0.5 degrees.

[2]
The diffusion sheet according to [1], wherein a ratio of the maximum value of the diffusion angle to the minimum value of the diffusion angle is 400 or more.
[3]
The diffusion sheet according to [1] or [2], wherein a streak pattern is provided in an oblique direction with respect to a direction in which the diffusion angle of the emitted light has a minimum value.
[4]
The diffusion sheet according to [3], wherein an angle formed between the streak pattern and a direction in which a diffusion angle of emitted light has a minimum value is 5 degrees or more.
[5]
The diffusion sheet according to [3] or [4], wherein the streak pattern is aperiodic.
[6]
The diffusion sheet according to any one of [3] to [5], wherein the streak pattern is discontinuous.
[7]
The diffusion sheet according to any one of [1] to [6], wherein the minimum value of the diffusion angle of the emitted light is 0.2 degrees or less.
[8]
The diffusion sheet according to any one of [1] to [7], wherein a minimum average pitch of the surface uneven structure is 20 μm or less.
[9]
The diffusion sheet according to any one of [1] to [8], wherein a maximum average pitch of the surface uneven structure is 5 mm or more.
[10]
The diffusion sheet according to [1] to [9], wherein the ratio of the maximum average pitch of the surface uneven structure to the minimum average pitch of the surface uneven structure is 200 or more.
[11]
The diffusion sheet according to [10], wherein the ratio of the maximum average pitch of the surface uneven structure to the minimum average pitch of the surface uneven structure is 400 or more.
[12]
The diffusion sheet according to any one of [1] to [11], wherein the maximum average aspect ratio of the surface uneven structure is 0.5 or more.
[13]
The diffusion sheet according to any one of [1] to [12], wherein the surface uneven structure is formed using a speckle pattern by interference exposure.
[14]
The diffusion sheet according to [13], wherein the speckle pattern is obtained by interference light diffused through a holographic diffuser having a minimum value of a diffusion angle of outgoing light of 0.1 degrees or less.
[15]
The diffusion sheet according to any one of [3] to [6], wherein the streak pattern is formed by sandblasting.
[16]
The diffusion sheet according to any one of [3] to [6], wherein the streak pattern is formed by a density distribution of the surface uneven structure.
[17]
A line illumination system comprising at least one point light source and the diffusion sheet according to any one of [1] to [16].
[18]
The line illumination system according to any one of [3] to [6], wherein the point light source is a light emitting diode (LED).
[19]

  By exposing and developing the photosensitive medium with the speckle pattern obtained by the interference light diffused through the holographic diffuser having a minimum value of the diffusion angle of the emitted light of 0.1 degrees or less, the non-difference derived from the speckle pattern is obtained. The method for producing a diffusion sheet according to any one of [1] to [16], wherein a submaster mold having a periodic surface irregularity structure is produced and transferred from the submaster mold at least once.

  According to the diffusion sheet of the third specification of the present invention, even when the interval is widened by reducing the number of point light sources in a line illumination system using point light sources, the uniformity of light on the irradiated surface is high, and the irradiated surface It is possible to suppress a decrease in the intensity of light at, and no moiré fringes are generated.

  Next, an embodiment (hereinafter referred to as “embodiment”) of the third invention of the specification will be described in detail with reference to the drawings. However, the third invention of the specification is not limited to the following description, and various modifications can be made within the scope of the gist thereof. In addition, the dimension ratio of drawing is not limited to the ratio of illustration.

FIG. 126 is a schematic diagram showing the configuration of the line illumination system according to the first embodiment as viewed obliquely from above. As shown in FIG. 126 , the light from the plurality of point light sources H1 arranged in the horizontal direction has a non-periodic surface uneven structure on at least one surface according to the first embodiment, and is in the normal direction. There is a direction in which the diffusion angle of the outgoing light of the light incident on the surface concavo-convex structure has a maximum value and a direction in which the minimum value is present, and the ratio of the maximum value of the diffusion angle to the minimum value of the diffusion angle is 200 or more, The irradiation surface H3 is irradiated through the diffusion sheet H2 having the maximum value of 40 degrees or more and less than 100 degrees and the minimum value of less than 0.5 degrees.

  The point light source H1 has a function of emitting light, and its display form, dimensions, and light distribution range are not limited. Although it is preferable to use a self-light-emitting light source as the point light source H1, the method is not limited, and examples thereof include an LED, an incandescent lamp, a halogen lamp, a mercury lamp, a xenon lamp, a sodium lamp, and a visible light laser. Among them, the LED is preferable because it has a low divergence of emitted light, so that it is easy to obtain a line-shaped illumination system that maintains high brightness even on the irradiation surface, high luminous efficiency, and miniaturization of the light source. Alternatively, the light source may be a single light source such as a COB type (Chip On Board type) LED or a plurality of light sources having a configuration in which a plurality of LED chips are mounted.

  Further, instead of the point light source, a linear light source such as a hot cathode tube or a cold cathode tube may be used.

  The diffusion sheet H2 includes a base material layer made of a light-transmitting and flat base material, and has a surface uneven structure on at least one surface of the base material layer. When using as a line-shaped illumination system, it is preferable to install the point light source H1 on the surface side having the surface uneven structure with respect to the diffusion sheet H2.

  As the base material layer, a light-transmitting sheet, film, film, plate, or the like can be used. As a material of the base material layer, an organic material, an inorganic material, or a composite material composed of an organic material and an inorganic material can be used. Here, an organic material such as an organic polymer material is a preferable material because it is excellent in workability such as cutting. Examples of the organic polymer include polycarbonate, polyurethane, polyacrylonitrile, polyvinyl alcohol, polyvinyl acetal, polyester, polyamide, polystyrene, polysulfone, cellulose, triacetyl cellulose, cellulose acetate, polyethylene, polypropylene, polyvinyl fluoride, polyvinylidene fluoride, Polytrifluorochlorovinyl, vinylidene fluoride-tetrafluoroethylene copolymer, polyethersulfone, poly (meth) acrylate, butadiene-acrylonitrile copolymer, polyether-polyamide block copolymer, ethylene-vinyl alcohol copolymer, cycloolefin polymer, etc. However, it is not limited to these. The thickness of the base material layer is preferably 40 μm or more. Moreover, it is preferable that the light transmittance of a base material layer is 85% or more.

  The concavo-convex structure on the surface of the diffusion sheet H2 is a structure composed of a large number of fine protrusions, and the protrusions are any of a substantially conical shape, a substantially spherical shape, a substantially ellipsoidal shape, a substantially lenticular lens shape, and a substantially parabolic shape. Alternatively, the protrusions may be connected by a continuous curved surface. It is preferable that at least one of the height and pitch of the protrusions is aperiodic. “Aperiodic” as used herein means that at least one of the height and pitch of several adjacent protrusions is random.

  Specifically, the uneven surface structure of the diffusion sheet H2 can be formed as follows. First, a submaster mold in which a speckle pattern is formed in advance by interference exposure is manufactured, and a master mold is manufactured by applying a metal to the submaster mold by a method such as electroforming to transfer the speckle pattern to the metal. . Furthermore, a speckle pattern is transferred to the surface of the light-transmitting substrate by shaping the light-transmitting substrate with an ultraviolet curable resin using a master mold (speckle pattern made of a cured ultraviolet curable resin) Form the layer on the surface of the substrate.). This speckle pattern corresponds to the surface uneven structure of the diffusion sheet H2.

  The speckle pattern is a light distribution pattern having random intensity generated by interference in the space after coherent light passes through the diffusion plate. A substrate having a photosensitive resin layer is installed in the space. By being exposed and developed, the surface is converted into a random surface uneven structure, and a submaster mold having the structure can be manufactured. In the present specification, this random surface uneven structure is also referred to as a speckle pattern.

  As for the detailed manufacturing method of the above-mentioned submaster type, a submaster having a non-periodic surface uneven structure derived from a speckle pattern by exposing and developing a photosensitive medium with interference light diffused through a holographic diffuser. A sheet having a concavo-convex structure can be obtained by producing a mold and transferring the surface structure from the sub-master mold to the sheet. By adjusting the size, shape, and direction of the speckle pattern, the surface uneven structure of the diffusion sheet H2 is adjusted, and the average pitch of the uneven structure can be controlled. As a method for adjusting the size / shape and direction of the speckle pattern, for example, a known method disclosed in Japanese Patent No. 3390954 can be used.

  Further, the uneven surface structure of the diffusion sheet H2 characterized by the speckle pattern may be provided only on one side of the diffusion sheet H2, or may be provided on both sides.

  In the case of the line illumination system according to the first embodiment, the diffusion sheet H2 is light-transmitting in order to irradiate light from the point light source onto the irradiation surface H3, and corresponds to the minimum value of the diffusion angle of the emitted light. The ratio of the maximum value of the diffusion angle of the emitted light is 200 or more, more preferably 400 or more. By using such a diffusion sheet H2, for example, in a line illumination system using a point light source, even when the number of point light sources is reduced and the interval is widened, the uniformity of light on the irradiated surface is increased. Is possible. Such a diffusion sheet H2 can be obtained by using a holographic diffuser having a speckle pattern with high anisotropy as a holographic diffuser used in the exposure for producing the above-mentioned sub-master type. The anisotropy in the holographic diffuser is given by the ratio of the maximum value of the diffusion angle to the minimum value of the diffusion angle of the holographic diffuser when the light transmitted through the holographic diffuser exhibits a different diffusion angle depending on the direction. It is done. The holographic diffuser having a highly anisotropic speckle pattern used to increase the ratio of the maximum value of the diffusion angle to the minimum value of the diffusion angle of the diffusion sheet H2 is specifically the minimum of the diffusion angle. The value is preferably 0.1 degrees or less, more preferably 0.05 degrees or less, and still more preferably 0.03 degrees or less. Further, the maximum diffusion angle is preferably 5 degrees or more, more preferably 10 degrees or more, and still more preferably 20 degrees or more.

  In the above-described method for producing a diffusion sheet by interference exposure, conventionally, a diffusion sheet has been produced using other diffusers such as a holographic diffuser filed glass having a certain level of diffusibility. However, by using a holographic diffuser having a diffusibility of a certain level or more, it is possible to manufacture the diffusion sheet H2 in which the ratio of the maximum value of the diffusion angle of the emitted light to the minimum value of the diffusion angle of the emitted light is 200 or more. Impossible. On the other hand, by using the holographic diffuser having the minimum value of the diffusion angle described above, the diffusion sheet H2 in which the ratio of the maximum value of the diffusion angle of the outgoing light to the minimum value of the diffusion angle of the outgoing light is 200 or more Can be manufactured.

  The minimum value (perpendicular direction) of the diffusion angle of the emitted light from the diffusion sheet H2 is preferably less than 0.5 degrees, more preferably less than 0.5 degrees in order to efficiently irradiate the irradiation surface H3 with light from the point light source. It is 2 degrees or less, more preferably 0.1 degrees or less.

  The maximum value (horizontal direction) of the diffusion angle of the emitted light from the diffusion sheet H2 is preferably 40 degrees or more, and more preferably 60 degrees or more in order to suppress unevenness of light between point light sources. The maximum value of the diffusion angle is preferably less than 100 degrees.

The diffusion angle of the emitted light is, for example, a variable angle photometer (GC-5000L) manufactured by Nippon Denshoku Industries Co., Ltd. or a beam profiler (NanoS) manufactured by Photon Inc.
The distribution of transmitted light intensity with respect to the emission angle of the light incident on the surface layer having the concavo-convex structure of the diffusion sheet H2 from the normal direction to the diffusion sheet H2 is measured using Can be obtained by obtaining a range (half-value width) of the diffusion angle that is a value of more than half of the above. The normal direction with respect to the diffusion sheet H2 is a direction perpendicular to the surface of the diffusion sheet H2.

  As a specific size of the surface uneven structure, the maximum ratio of the maximum value of the diffusion angle of the outgoing light to the minimum value of the diffusion angle of the outgoing light is set to 200 or more, particularly from the viewpoint of increasing the maximum diffusion angle. The average aspect ratio is preferably 0.5-3. The aspect ratio is defined by the ratio (height / width) of the height of the convex portion to the width of the convex portion at a position that is 1/2 the height of the convex portion. The maximum average aspect ratio is given by the maximum value of the average aspect ratio in each direction obtained by scanning the surface of the diffusion sheet in various directions.

  The minimum value of the average pitch of the surface concavo-convex structure of the diffusion sheet H2 is that the ratio of the maximum value of the diffusion angle of the outgoing light to the minimum value of the diffusion angle of the outgoing light is increased to 200 or more, in particular, the maximum diffusion angle is increased. From a viewpoint, it is preferable that it is 100 micrometers or less, More preferably, it is 20 micrometers or less, More preferably, it is 10 micrometers or less, More preferably, it is 5 micrometers or less. Here, by setting the thickness to 20 μm or less, it is possible to further suppress a rough feeling on the appearance of the diffusion sheet H2. Further, the minimum value of the average pitch is preferably 580 nm (the central wavelength of visible light) or more, and more preferably 780 nm (the upper limit wavelength of visible light) or more. The average pitch is the average of the pitches between the peaks or the bottoms of the surface uneven structure of the diffusion sheet H2, and is observed using an optical microscope, a scanning electron microscope, a laser microscope, and a surface shape measuring instrument. Can be measured. The minimum value of the average pitch is given by the minimum value of the average pitch in each direction obtained by scanning the surface of the diffusion sheet in various directions.

  The maximum value of the average pitch of the surface concavo-convex structure of the diffusion sheet H2 is that the ratio of the maximum value of the diffusion angle of the outgoing light to the minimum value of the diffusion angle of the outgoing light is 200 or more. From the viewpoint, it is preferably 1 mm or more, more preferably 5 mm or more, and further preferably 10 mm or more. The maximum value of the average pitch is given by the maximum value of the average pitch in each direction obtained by scanning the surface of the diffusion sheet in various directions.

  Further, the diffusion sheet H2 has a ratio of the maximum average pitch to the minimum average pitch of the surface uneven structure from the viewpoint that the ratio of the maximum value of the diffusion angle of the output light to the minimum value of the diffusion angle of the output light is 200 or more. However, it is preferable that it is 200 or more, More preferably, it is 400 or more, More preferably, it is 600 or more.

  The diffusion sheet H2 may be composed of two or more layers. For example, a surface layer having a surface concavo-convex structure may be formed on a smooth substrate layer with an ultraviolet curable resin.

FIG. 127 is a schematic diagram showing the diffusion sheet H2 according to the second embodiment as viewed from above. The diffusion sheet H2 has a non-periodic anisotropic surface uneven structure on at least one surface, and as shown in FIG. 127 , the diffusion sheet H2 has streaks obliquely with respect to the direction H6 in which the diffusion angle of the emitted light has the minimum value. A pattern H5 is formed in the same plane. The streak pattern H5 includes, for example, a plurality of grooves or protrusions (ridges) provided substantially parallel to the diffusion sheet H2. Alternatively, the streak pattern H5 is formed by changing the density distribution of the surface uneven structure into a streak. By forming the streak pattern H5, when the surface having the concavo-convex structure is rubbed and scratched, the effect that the scratch is lost in the streak pattern H5 is less visible. In addition, since the streak pattern H5 is formed, when the uneven surface is stressed, an effect of preventing the occurrence of scratches by rubbing along the streak pattern H5 is also exhibited.

  The average pitch of the streak pattern H5 is preferably 2 mm or less, more preferably 1 mm or less, and still more preferably 0.5 mm or less for improving the scratch resistance.

  Here, the average pitch of the streak pattern H5 is the average of the pitch of the streak pattern that can be visually confirmed, and can be measured by observing using an optical microscope, a loupe, or the like. As will be described later, in the case of the streak pattern H5 formed by sandblasting or the like, the interval between the irregularities of the streak pattern H5 can be measured as a pitch. Further, when the streak pattern H5 is formed by the density distribution of the surface uneven structure, the density density interval can be measured as the pitch.

  The angle H7 of the streak pattern H5 with respect to the direction H6 that gives the minimum value of the diffusion angle of the emitted light is preferably 5 degrees or more, more preferably 10 degrees or more for sufficient scratch resistance.

  In order not to inhibit the diffusibility of the diffusion sheet H2, the angle H7 is preferably less than 30 degrees, more preferably less than 20 degrees.

  The non-periodic streak pattern H5 means that moire interference fringes occur when the diffusion sheet H2 is used between a light source and a display device composed of regularly arranged pixels such as a liquid crystal panel. It is preferable because it is difficult to do.

  For sufficient abrasion resistance, the streak pattern H5 is preferably discontinuous.

  The streak pattern H5 can be formed by subjecting the sub-master type or diffusion sheet H2 having a surface uneven structure to sand blasting obliquely in the direction H6 that gives the minimum value of the diffusion angle of the emitted light, for example. it can.

  For example, rubbing with a roll or a wire having a sandpaper or a concavo-convex surface obliquely against the submaster type or diffusion sheet H2 having a surface concavo-convex structure, for example, in a direction H6 giving the minimum value of the diffusion angle of the emitted light It can be used as a method for forming the streak pattern H5.

  When the streak pattern H5 is formed by sandblasting, sandpaper, roll, wire, or the like, the average aspect ratio of the streak pattern H5 is 0.2 or less in order to avoid adverse effects on the diffusibility of the diffusion sheet H2. Is preferable, more preferably 0.1 or less, and still more preferably 0.05 or less.

  Another method for forming the streaky pattern H5 is to adjust the exposure intensity and the pitch of the speckle pattern when producing a sub-master type by interference exposure, thereby distributing the density of the sub-master type surface uneven structure. You can also have it. By providing the density of the surface uneven structure, the streak pattern H5 can be visually recognized in an oblique direction with respect to the direction H6 that gives the minimum value of the diffusion angle of the emitted light.

  The third invention of the specification can be suitably used in the field of an illuminating device having a line light source system and an inspection device.

Next, a description will be given of a fourth invention of the present specification relating to a bonding method and a bonding jig that can be suitably used for manufacturing a light guide plate used in the present invention.
Specification 4th invention relates to a pasting method and a pasting jig, especially relates to a pasting method and a pasting jig suitable for pasting an optical film on one end face of a plate-like member.

  The main surface of a film-like member having two substantially parallel principal surfaces, or the principal surface of a plate-like member having a substantially parallel two principal surfaces and a narrow end face located between the edges of the two principal surfaces, are optical. Products and methods of pasting films and protective films are well known. On the other hand, the product which bonded the optical film to the end surface of a plate-shaped member, and the method to bond were few and were not common. One reason for this is that the end face rarely had a positive function in the use of the plate-like member.

  However, in recent years, a plate-like member whose end face has a positive function has been proposed. As an example, a light guide plate used as a component of an edge light type surface light source device in a liquid crystal display device can be given. In the edge light type surface light source device, a light guide plate is disposed on the back surface of the liquid crystal display panel, and a light source is disposed on one end surface (side surface) of the light guide plate. With this structure, it is possible to reduce the thickness as compared with a direct surface light source device in which a light source is directly disposed on the back surface of a liquid crystal display panel. A normal light guide plate is a rectangular transparent resin plate having a thickness of about 0.5 to 10 mm and slightly larger than the liquid crystal display panel. One end surface (side surface) is a light incident surface, and the main surface on the liquid crystal display panel side is Used as a light exit surface. Such a light guide plate is used in lighting applications including indoor lighting and automobile lighting in addition to liquid crystal display devices.

  Some light guide plates described above have a tape-like optical sheet bonded to one end surface for the purpose of improving optical characteristics. Specifically, a light guide plate in which a reflective sheet is bonded to an end surface other than the light incident surface for the purpose of reducing light leakage from the end surface, or anisotropic light on the light incident surface (end surface) for the purpose of reducing luminance unevenness. A light guide plate on which a diffuser sheet is bonded has been proposed (see, for example, JP-A-2011-3532).

  However, in JP 2011-3532 A, there is a description that the anisotropic light diffuser sheet is bonded to the light guide plate with a highly transparent double-sided adhesive tape. There is no description.

  In addition, when an optical film is bonded to one end surface of a plate-like member having two substantially parallel principal surfaces and one or more end surfaces, it may be necessary to bond so that air bubbles do not enter the interface. . For example, in the example of the light guide plate described above, when a reflection sheet is bonded to the end face, even if bubbles enter the interface, the same effect can be obtained, so that there is no major problem if it does not peel off. However, in the case where the above-mentioned anisotropic light diffuser sheet is bonded to the light incident surface, the presence of bubbles adversely affects the optical characteristics and a desired light diffusion effect cannot be obtained. Furthermore, the presence of bubbles often becomes a problem in appearance.

  Therefore, if air bubbles enter the interface where the optical film is bonded, the optical film may be peeled off and reattached, or the air bubble may be pushed out by hand to allow air inside the air bubbles to escape from the interface. Although considered, these methods are not productive. In particular, when an optical film is bonded to a plurality of stacked light guide plates, for example, several tens of centimeters with respect to the side end surfaces of the light guide plates that are recessed due to unevenness of the end surfaces of the light guide plates. It is difficult to paste a strip-shaped optical film without deviating over the above length, and it is also difficult to eliminate bubbles by the above method. Moreover, even if it is one plate-shaped member, when one end surface is rough, similarly, it is difficult to eliminate air bubbles in the recessed portion.

  The fourth invention of the specification has been made in view of the above points, and an object thereof is to provide a method for efficiently bonding an optical film to one end face of a plate-like member without bubbles.

  The inventors of the specification 4th invention, as a result of earnest study, a bonding jig provided with a member having shape followability, and a bonding method using the bonding jig solved the above-mentioned problems. As a result, the fourth invention of the specification was completed.

That is, the specification 4th invention is as follows.
[1]
A tape-like member in which an adhesive material layer and an optical film layer are laminated on one end face of a plate-like member having two substantially parallel principal surfaces and one or more end faces, and the one end face of the plate-like member A method of laminating a tape-shaped member having a width substantially equal to or narrower than the thickness,
A laminating step in which the adhesive layer of the tape-shaped member is opposed to the one end surface, and the tape-shaped member is laminated on the one end surface;
A sticking jig comprising a member having shape followability, and an adhesion step of tracing the optical film layer one or more times while applying pressure in the longitudinal direction of the one end face;
A laminating method.
[2]
The laminating method according to [1], wherein the laminating step includes a step of pressing a plurality of locations on the optical film layer laminated on the one end surface to the one end surface.
[3]
The laminating method according to the preceding item [1] or [2], wherein the laminating step and the adhesion step are performed in a state where a plurality of the plate-like members having the same shape are stacked in a multistage manner.
[4]
The bonding method according to [3], wherein the adhesion step includes a step of simultaneously tracing one end surface of the plurality of plate-like members in the longitudinal direction with a member having the shape following property.
[5]
In the above item [3] or [4], the laminating step and the adhesion step are steps performed in a state where a plurality of plate-like members are stacked in a multi-step manner with a step between adjacent plate-like members being 500 micrometers or more. The bonding method described.
[6]
The preceding item is a step that is performed in a state where the plurality of plate-like members having the same shape are stacked in a multi-stage, and the adhesion step is a step that is performed in a state where the plate-like members are made one by one The pasting method according to [1] or [2].
[7]
The bonding method according to any one of [1] to [6], wherein a surface roughness of one end surface of the plate-shaped member is 500 micrometers or more.
[8]
The bonding method according to any one of [1] to [7], wherein the thickness of the plate member is in a range of 0.5 to 10 millimeters.
[9]
The bonding method according to any one of [1] to [8], wherein the surface of the optical film layer has an uneven structure having light diffusibility.
[10]
The bonding method according to any one of [1] to [9], wherein the optical film layer has a pencil hardness of 5H or less.
[11]
The lamination step and the adhesion step are such that the length of the tape-like member is longer than the length of one end surface of the plate-like member, and at least one end of the tape-like member protrudes in the longitudinal direction from the one end surface. The bonding method according to any one of [1] to [10], wherein the bonding step includes a cutting step of cutting a portion of the tape-shaped member protruding from one end surface of the plate-shaped member. [12]
The bonding method according to any one of [1] to [11], wherein the tape-shaped member has both ends, and has a marking in the vicinity of at least one end.
[13]
The bonding method according to any one of [1] to [12], wherein the tape-shaped member is supplied from a reel onto one end surface of the plate-shaped member in the stacking step.
[14]
A laminating jig for tracing an optical film laminated on an end face of a plate-like member via an adhesive material layer, comprising a member having shape followability.
[15]
Located on the surface of the bonding jig, a slipperiness-imparting layer made of a slipperiness-providing material,
A shape following layer made of a material having a shape following property located inside the slipperiness-imparting layer;
A bonding jig according to the preceding item [14].
[16]
The bonding jig according to [14] or [15] above, wherein the material having the shape following property is a material having a rubber hardness of 10 to 70.
[17]
[16] The bonding jig according to [14] or [15] above, wherein the material having the shape following property is an elastic body.
[18]
The bonding jig according to [17], wherein the elastic body is made of rubber or sponge.
[19]
The bonding jig according to [17], wherein the elastic body is a sponge having a sponge hardness of 5 to 50. [20]
The bonding jig according to [14] or [15], wherein the material having the shape following property is a plastic deformable body.
[21]
A bonding jig for tracing the optical film laminated on the end face of the plate-like member via an adhesive material layer, the bonding jig comprising a member having shape following property;
A reel for holding the tape-shaped member wound in order to supply a tape-shaped member including the laminated adhesive material layer and the optical film on one end surface of the plate-shaped member;
And a pinch roller for moving along the one end face with the two main surfaces of the plate-like member sandwiched therebetween.

  According to the bonding method and the bonding jig according to the fourth specification of the present invention, it becomes possible to efficiently bond the optical film to the one end surface of the plate-shaped member without bubbles.

  Hereinafter, modes for carrying out the specification fourth invention (hereinafter abbreviated as “embodiments”) will be described in detail with reference to the drawings as appropriate. The fourth specification invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the invention.

In the bonding method according to the embodiment, an adhesive material layer and an optical film layer are laminated on one end surface of a plate-like member I1 having two substantially parallel main surfaces and one or more end surfaces as shown in FIG. This is a method of laminating a tape-like member I2 having a width substantially equal to or narrower than the thickness of one end surface of the plate-like member I1. The laminating process according to the embodiment includes a laminating step in which the adhesive material layer of the tape-like member I2 is opposed to one end surface of the plate-like member I1, and the tape-like member I2 is laminated on one end surface of the plate-like member I1. A bonding jig provided with a member having shape followability, and an adhesion step of tracing the optical film layer one or more times while applying pressure in the longitudinal direction of one end surface of the plate-like member I1.

  The plate-like member I1 used in the bonding method according to the embodiment is a member having two substantially parallel main surfaces and one or more end surfaces, and is made of, for example, transparent resin or glass, and the main surface is rectangular. A plate-shaped member, more specifically, a light guide plate. The thickness of the plate-like member I1 to which the bonding method according to the embodiment can be preferably applied is 0.5 mm to 10 mm, more preferably 1 mm to 5 mm, and most preferably 1.5 mm to 4 mm.

  The tape-like member I2 used in the bonding method according to the embodiment refers to a tape-like member in which an adhesive material layer and an optical film are laminated, for example. Such a tape-like member I2 is a known laminate in which a pressure-sensitive adhesive dissolved in a solvent is applied to one of the main surfaces of the optical film and dried, or a double-sided pressure-sensitive adhesive sheet is stacked on one of the main surfaces of the optical film. The laminated body produced without bubbles can be produced by a method of cutting into a tape shape.

  In the following, the bonding method according to the embodiment is a light diffusion film (optical) in which the plate-like member I1 is a light guide plate, one end face is a light incident surface of the light guide plate, and the tape-like member I2 is laminated with an adhesive layer. An example of a kind of film will be described.

  In the case of a light guide plate for a television, the size of the main surface of the light guide plate is determined by the size of the television screen. For example, the length of the long side is about 70 cm in the case of a 32-inch television, but reaches 133 cm in the case of a 60-inch television. For example, when the light guide plate has a thickness of 3 mm and is bonded over the long side of the light guide plate for a 32-inch television, the size of the light diffusion film to be bonded is, for example, a width of 2.8 mm and a length of 70 cm. Become.

  The width of the light diffusing film is set between 110% and 20% with respect to the thickness of the light guide plate, depending on the optical performance required, preferably 100% to 40%, more preferably 99% to 50%, Most preferably, it is 95% to 80%. If the width of the light diffusing film is 110% or less with respect to the thickness of the light guide plate, there is little possibility of partial peeling due to being caught by interference with other members. If the width is 20% or more, desired optical characteristics such as light diffusibility can be obtained.

  The lower limit of the length of the light diffusion film is a length that can secure an area in which light sources (LED chips) are arranged, and the upper limit can be several cm longer than the length of one end face of the light guide plate to be bonded.

As shown in FIG. 137 , in the state where a plurality of light guide plates 1 are stacked in the main surface direction, when the light diffusion film 2 is bonded to one end surface of each light guide plate, each end surface is adjacent to each light guide plate. There is a difference in level, and there are things that are deep and those that have popped out. At this time, if the light diffusion film is pasted by hand on one end surface of the recessed light guide plate, and the light guide plate is thin, for example, 3 mm, and the hand does not enter the recessed portion, the light diffusion film If one end of the light guide plate protrudes in the longitudinal direction of the one end face of the light guide plate, it is preferable because the position is adjusted so that it does not deviate from the width of the one end face of the light guide plate over the length of the film. Moreover, you may perform a close_contact | adherence process in the state which made the plate-shaped member one sheet at a time.

  It is more preferable that the end portion on the bonding end side protrudes in the longitudinal direction so that it can be securely gripped, and it is also possible to suitably adopt a state where both end portions of the light diffusion film protrude from one side surface of the light guide plate. By making the light diffusing film protrude from one end face of the light guide plate, the visibility is improved, and when sticking one by one to the stacked plate-like members, it is possible to prevent forgetting to stick. This has the advantage that it can be easily inspected. In addition, there is an advantage that it is easy to peel off when re-bonding is necessary, for example, when the film has deviated from the width of one end face of the light guide plate.

  The protruding length is an amount sufficient for gripping, and is preferably 5 mm to 30 mm. If it is less than 5 mm, it is difficult to grip, and if it is 30 mm or more, the light diffusion film tends to be wasted. It is preferable to remove the protruding portion by using a cutter at least in the stage before the product is finished and at least before becoming a product.

  The thickness of the light diffusion film is preferably 30 to 300 μm. If thickness is 30 micrometers or more, it exists in the tendency for it to reduce at the time of bonding. In addition, when the thickness is 300 μm or less, bubbles tend to be easily extracted in the adhesion process. Further, the thickness of the adhesive layer is preferably 10 to 70 μm. If the thickness is 10 μm or more, the adhesive force can be sufficiently secured, and it tends to be possible to suppress natural peeling due to thermal shock or the like. Moreover, if thickness is 70 micrometers or less, it exists in the tendency for it to become easier to extract a bubble by the contact | adherence process.

  In the bonding method according to the embodiment, the optical film layer and one end face of the plate-like member are traced once or more in the longitudinal direction of the one end face while applying pressure on the optical film layer with a member having shape followability. Air bubbles between them can be easily removed. The member having the shape following property will be described later. At this time, in the laminating process before the adhesion process, it is possible to include a temporary fixing process in which a plurality of locations on the optical film layer are pressed against one end surface.

  Moreover, a lamination | stacking process and a contact | adherence process can be performed in the state which piled up the several plate-shaped member which has the same shape. Furthermore, a lamination process can be performed in a state where a plurality of plate-like members having the same shape are stacked in multiple stages, and a contact process can be performed in a state where the plate-like members are made one by one.

When the optical film layer is transparent, as shown in FIG. 138 , a marking I3 can be provided on one or both ends of the tape-like member I2 to improve visibility. When one end surface of the plate-like member I1 is longer than about 1 m, it is possible to bond with two optical films. In this case, for example, two markings provided on the tape-like member are attached to the plate-like member. Aligned with both ends of one end surface of the tape, or bonded after aligning the center of the marking, or by bonding two films after aligning the marking with the end surface and the center respectively. It becomes easy to paste in position. Moreover, when bonding one sheet at a time to a multi-layered plate-like member, there is an advantage that it is possible to prevent forgetting to bond and to facilitate inspection.

  In the case where the tape-like member sticks out from the one end surface of the plate-like member in the longitudinal direction, the marking position can be appropriately selected depending on the end of the tape-like member or the end of the plate-like member. As a marking method, there are a method of drawing a line with a marker and a method of pasting a colored tape on a portion to be marked. As the marker, commercially available sign pens, magic inks, pens using thermal fading ink, and the like can be used. Pens using thermal fading ink are marked on the final product because the marking disappears due to frictional heat generated in the process of sliding on the film layer while applying pressure with a shape-following member after pasting the tape-like member It can be preferably used when there is a need not to leave. Various tapes can be used as colored tapes, but if there is a need to leave no marking on the final product, the tape can be peeled off after bonding by marking with a slightly sticky tape. Can be preferably used.

As shown in FIG. 139 , the tape-like member I2 can be supplied to one end surface of the plate-like member I1 by a reel cartridge. The reel cartridge is a tape-like member I2 wound around a reel, and the tape-like member I2 composed of an optical film layer, an adhesive material layer, and a release paper layer is peeled off from the release paper I5 and wound up. The plate-like member I1 is supplied onto one end surface of the plate-like member I1 so that the side faces the one end surface of the plate-like member I1. The guide roller I10 can be provided so as not to deviate from the width of one end surface of the guide. Further, it is preferable to provide a pinch roller I9 that sandwiches the two main surfaces of the plate-like member I1 from both sides. Moreover, a lamination process and an adhesion | attachment process can also be performed simultaneously or continuously by providing the bonding jig I4 which has the shape followability mentioned later in a supply port. In the tape-like member I2, the optical film layer may have a function of a release layer. In this case, the tape-like member I2 may not include the release paper I5.

A bonding jig I4 according to the embodiment shown in FIG. 140 is a jig suitable for performing the adhesion process in the bonding method according to the embodiment. The bonding jig I4 according to the embodiment includes a contact portion I6 that comes into contact with the surface of the optical film layer, and the contact portion I6 is a member having shape followability, so that one of the plate-like members I1 is applied while applying pressure. By tracing once or more in the longitudinal direction of the end face, the tape-like member I2 can be brought into close contact with the one end face of the plate-like member I1 while eliminating bubbles. Here, “tracing” includes both a case where the bonding jig I4 including a member having a shape following property is slid on the surface of the optical film layer and a case where it is rolled.

  The member having the shape following property of the bonding jig I4 is preferably an elastic body such as rubber or sponge, or a plastic deformation body having the shape following property. Further, the hardness of the material having the shape following property is preferably 10 to 70, more preferably 35 to 65, and most preferably 40 to 60. In addition, when the material which has shape followability cannot measure rubber hardness with sponge etc., sponge hardness can be substituted, and it is preferable that it is 5-50 in that case. By using such a shape-following member, especially when the hardness is 5 or more, the applied stress is efficiently propagated to the stress in the direction perpendicular to the one end surface, effectively eliminating bubbles. However, it tends to be able to be in close contact. At this time, the elastic body can withstand long-term use. If the hardness is 70 or less, the shape followability to the applied stress is excellent, the contact area can be secured above a certain level even if the jig is slightly inclined with respect to the width direction, and the uniformity of the bubble removal in the width direction of one end face is excellent. There is a tendency.

As shown in FIGS. 140 (b) and 140 (c), the labeling jig 4 according to the embodiment has a surface roughness of one end face of the plate-like member I1 of 500 μm or more, or is multi-tiered. Even in the case where the step between adjacent one end faces of the plate-like member I1 is about 500 μm to 5 mm, the shape following property is sufficient, so that it is possible to remove bubbles by tracing a plurality of plate-like members I1 at a time. Furthermore, even if there is a concavo-convex structure having light diffusibility on the surface of the optical film, even if the optical film is a flexible film having a pencil hardness of 5H or less, it is difficult to be scratched. Can be maintained.

  In addition, in the state which applied the pressure in a close_contact | adherence process, the length (contact length) which the bonding jig | tool I4 which concerns on embodiment is contacting with the longitudinal direction of the tape-shaped member I2 is 0.5 mm-15 mm. Preferably, 0.8 mm to 5 mm is more preferable, and 1 mm to 3 mm is most preferable. When the contact length is 0.5 mm or more, bubbles tend to be efficiently eliminated, and when the contact length is 15 mm or less, the applied force tends to be propagated to stress for efficiently eliminating bubbles, The operator is less tired when manually pasting.

Materials of shape-following members are acrylic rubber, nitrile rubber, isoprene rubber, urethane rubber, ethylene propylene rubber, chlorosulfonated polyethylene, epichlorohydrin rubber, chloroprene rubber, silicone rubber, styrene / butadiene rubber, butadiene rubber, fluorine rubber , Polyisobutylene, butyl rubber, nitrile / butadiene rubber, tetrafluoroethylene / propylene rubber, hydrogenated NBR, chlorinated polyethylene, ethylene acrylate rubber, norbornene rubber, fluorosilicone rubber, natural rubber, polyurethane foam, polyethylene foam, EVA It is selected from foam, silicone foam, acrylic foam, polyimide foam, EPDM foam, and the like. Specifically, silicone foam manufactured by Dow Corning Bar Silastic J-RTV and Code Seal <Soft> manufactured by Nippon Valqua Industries, Ltd. can be preferably used.

As shown in FIG. 141 (a), the contact portion I6 of the bonding jig I4 according to the embodiment may be composed of only the shape following layer I8 made of a material having a shape following property. Alternatively, as shown in FIGS. 141 (b) and 141 (c), on the outermost surface portion of the contact portion I6 of the bonding jig I4, a slip applying layer 7 made of a slip providing material can be provided smoothly. One end surface can be traced in the longitudinal direction, and workability can be further improved. In particular, when the surface of the optical film layer in contact with the contact portion I6 of the bonding jig is smooth, the effect is remarkable. In this case, the slip-imparting layer 7 may be a laminate with the shape following layer I8 existing on the inner side, or may have an inclined structure. In the case of lamination, the shape following layer I8 may be coated with a slip-providing material, or the slip-providing material may be fixed to the shape following layer I8. The presence of this slip-imparting material gives the effect of extending the life of the internal shape tracking layer I8 and the effect of preventing the scattering of the shape tracking material. It can also be used.

  As the slipperiness imparting material, polyethylene, polypropylene, vinyl chloride, fluororesin, polyoxymethylene and the like are selected. In the case of a film or tube having heat shrinkability, the shape following layer I8 is coated with a slipperiness-imparting material, and then adhered by heating and shrinking, so that wear of the material due to slippage between the two can be suppressed and bonding treatment can be performed. The tool life can be extended.

  The bonding jig I4 can include a grip portion by a human hand or a robot arm in addition to the contact portion I6. In this case, it is preferable that the contact portion I6 and the grip portion are integrated, and the contact portion I6 is slid in the longitudinal direction of the one end face while applying pressure. In other words, the applied stress can be propagated to the stress for efficiently eliminating the bubbles by controlling and applying the dynamic friction better than the rolling friction. In that case, a rectangular parallelepiped, a square weight, or the like is selected as the shape of the bonding jig I4, and one side or one vertex thereof is set as the contact portion I6, and pressure is applied.

  Moreover, if it adheres one piece at a time, it can also be set as the shape which has the groove | channel which matched the shape of the bonding jig 4 with the thickness of the plate-shaped member I1.

  On the other hand, the shape of the bonding jig is a roll, and both sides of the plate-like member, for example, both end faces are sandwiched and pressed so as not to give a moment with the rolls, and the plate-like member is fed while being rotated and bonded. it can. In this case, since the perpendicular stress is applied to the one end face almost efficiently by pressing with the roll, it is possible to achieve close contact while removing bubbles.

  As one of the methods for producing the light guide plate of the present invention, the method for pasting the pressure-sensitive adhesive sheet (seal) having a concavo-convex structure to the light guide plate substrate has been described above. About this invention specification 5 invention regarding the manufacturing method of the sheet | seat with an adhesive material in which the uneven structure was formed in the surface suitable for using in this method, an opening part or a bottom face which shows a remarkable effect also in a concavo-convex structure is one direction. The following description will be given in the form of an example of a concavo-convex structure (hereinafter referred to as “vertical groove structure”) composed of a plurality of concave portions or convex portions having a long anisotropic shape. However, the fifth invention of the specification is not limited to the illustrated longitudinal groove structure, and can be applied to a sheet with an adhesive (seal) having various uneven structures.

(Vertical groove sheet roll manufacturing method)
First, a sheet in which a resin layer having a longitudinal groove structure (also referred to as a “longitudinal groove layer”) is laminated on a base material is wound around a core tube in a roll shape (hereinafter referred to as “longitudinal groove sheet roll”). .) Will be described.
A base material wound in a roll shape around a core tube is unwound from the core tube (unwinding step), a photopolymerizable resin composition is applied (application step), and a cylindrical shape having a concavo-convex structure on the surface of the cylindrical surface By irradiating with ultraviolet rays while pressing against the mold, a UV curable resin layer obtained by curing the photopolymerizable resin composition is formed on one side of the substrate (curing step), and the substrate and the resin layer are laminated. A method for producing a roll-shaped film having a concavo-convex structure on the surface by winding the resulting sheet in a roll shape around another core tube (winding step) is well known (for example, JP-A-7-32476). reference).
In this method, by using a cylindrical mold having a longitudinal groove structure on the surface of the cylindrical surface, a longitudinal groove sheet roll J1 in which a sheet made of a base material and a longitudinal groove layer is wound in a roll shape can be produced. At this time, in order to prevent the longitudinal groove layer from being damaged, it is preferable to wind up so that the longitudinal groove layer is inside the roll. Preferable examples include a longitudinal groove sheet roll J1 in which the base material is a PET film having a thickness of 125 μm and the longitudinal groove layer is a UV curable resin layer having a thickness of 15 μm.

(Manufacturing method A1: Adhesive vertical groove sheet roll)
Second, a sheet in which a heavy release separator, an adhesive layer, a base material, and a longitudinal groove layer are laminated in this order using the longitudinal groove sheet roll is wound around a core tube in a roll shape (hereinafter referred to as “adhesive”). A first method of manufacturing a longitudinal groove sheet roll with material ”will be described ( FIG. 150 ).
A material prepared by laminating a pressure-sensitive adhesive film in which a heavy release separator, a pressure-sensitive adhesive layer, and a light release separator are laminated in this order on a core tube (hereinafter referred to as “pressure-sensitive film roll”) is prepared.
While unwinding the sheet 1 which consists of a base material and a longitudinal groove layer from the said longitudinal groove sheet roll J1 (longitudinal groove sheet roll unwinding process), unwinding an adhesive film from the said adhesive film roll (adhesive film roll unwinding process) The light release separator is peeled from the unrolled adhesive film to form a sheet 2 composed of a heavy release separator and an adhesive layer (peeling step), and laminated so that the adhesive layer of the sheet 2 and the base material of the sheet 1 are in contact with each other. Bonding is performed by applying pressure with a sheet roll (bonding step).
By winding the sheet, in which the heavy release separator, the adhesive layer, the base material, and the longitudinal groove layer are laminated, in a roll shape onto another core tube after the pasting (adhesive longitudinal groove sheet roll winding step) The fluted sheet roll J2 with adhesive is manufactured. Also in the longitudinal groove sheet roll J2 with an adhesive, it is preferable to wind up so that the longitudinal groove layer is inside the roll. Preferable examples include PET film having a heavy release separator having a thickness of 75 μm, an adhesive for an optical adhesive having a thickness of 25 μm, a PET film having a thickness of 125 μm, and a UV curing having a vertical groove layer having a thickness of 15 μm. The adhesive grooved fluted sheet roll J2 which is a resin layer is illustrated.

(Manufacturing method A2 of longitudinal groove sheet roll with adhesive material: coating method)
Third, a sheet in which a heavy release separator, an adhesive layer, a base material, and a longitudinal groove layer are laminated in this order using the longitudinal groove sheet roll is wound around a core tube in a roll shape (hereinafter referred to as “adhesive”). A second method for producing a “longitudinal groove sheet roll with a material” will be described ( FIG. 151 ).
A heavy release separator is prepared by winding a core tube in a roll (hereinafter referred to as “heavy release separator roll”).
The sheet 1 composed of a substrate and a longitudinal groove layer is unwound from the longitudinal groove sheet roll J1 (longitudinal groove sheet roll unwinding step), and a coating device (for example, a die coater) is used to apply a solvent Apply the adhesive material dissolved in (application process), volatilize the solvent by heating to form a sheet 2 with an adhesive layer (drying process), and unwind the heavy release separator from the heavy release separator roll (heavy release) Separator roll unwinding step), laminating so that the heavy release separator and the adhesive layer of the sheet 2 are in contact, and applying pressure with a roll (bonding step). By winding the sheet, in which the heavy release separator, the adhesive layer, the base material, and the longitudinal groove layer are laminated, in a roll shape onto another core tube after the pasting (adhesive longitudinal groove sheet roll winding step) The fluted sheet roll J2 with adhesive is manufactured. About the suitable aspect of the longitudinal groove sheet roll J2 with an adhesive material, it is the same as the 1st method mentioned above.
However, since the adhesive material is directly applied in the second production method, it takes time to store the adhesive material before use, called a curing period, in order to stabilize the physical properties of the adhesive material. The curing period is preferably about 2 weeks, although it depends on the adhesive used.

(Half slit sheet manufacturing method)
Fourth, a method for producing a half slit sheet using the longitudinal groove sheet roll with longitudinal groove adhesive will be described.
The sheet wound in a roll shape includes a direction in which the sheet is unwound from the roll and wound (hereinafter referred to as “MD direction”) and a width direction of the roll (hereinafter referred to as “TD direction”).
On the other hand, in the case of a sheet composed of a base material laminated on the light incident surface of the light guide plate used in the present invention via an adhesive layer (adhesive layer) and a resin layer having a longitudinal groove structure, the diffusion angle of the longitudinal groove structure is The low direction (direction parallel to the ridge line of the longitudinal groove) is the thickness direction (short side direction) of the light incident surface, and the direction in which the diffusion angle of the longitudinal groove structure is high (the direction perpendicular to the ridge line of the longitudinal groove) is the incident light. The width direction of the surface (long side direction) is required.
Therefore, in the following, by Figure 152, describes the half-slitting method when flutes sheet roll J2 is a high diffusion sheet in TD by Figure 153, the longitudinal grooves sheet roll J2 is it high diffusion in the MD direction The half slit processing method in the case of a sheet will be described.

(Manufacturing method B of a half slit sheet in the case of high diffusion in the TD direction)
FIG. 152 shows the flow of processing from the upper left to the lower right.
In the case of a sheet roll having a high diffusion in the TD direction, a fluted sheet roll (21 with a high diffusion in the TD direction) J21 is used with a single blade so that the length in the MD direction becomes the sheet width of the final product of the half slit sheet. To cut in the TD direction (step B1). The width at this time is parallel to the direction in which the half slits are inserted in the subsequent process, and is performed to determine how many half slits are to be formed on one sheet.
Next, it cuts in MD direction with a single blade so that the length of a TD direction may become the length of the long side of the sheet | seat bonded to the light-incidence surface of a light-guide plate, and it is set as the longitudinal groove sheet J3 with an adhesive material (process). B2). At this time, one end portion in the TD direction may be cut or both end portions may be cut, but the latter is preferable from the viewpoint of quality uniformity. However, the length of the long side of the sheet to be bonded to the light incident surface of the light guide plate need not be limited to the same length as the long side of the light incident surface of the light guide plate. This includes cases where the length is shorter than the length. This is because a plurality of individual longitudinal groove seals J5 with adhesive material may be bonded in the long side direction, or may be bonded slightly short.
Finally, the flute separator with adhesive material is cut off in the TD direction with a single blade so that the longitudinal groove sheet J3 with adhesive is the length of the short side of the sheet bonded to the light incident surface of the light guide plate. The half slit which cuts to a vertical groove layer, a base material, and an adhesion layer is performed, and it is set as the half slit sheet J4 (process B3). At this time, the direction of inserting the half slit is substantially parallel to the high diffusion direction and is perpendicular to the ridgeline of the longitudinal groove structure.

(Method C of producing a half slit sheet in the case of high diffusion in the MD direction)
FIG. 153 shows a processing flow from the upper left to the lower right.
In the case of sheet rolls with high diffusion in the MD direction, the longitudinal groove sheet roll with adhesive (MD direction high diffusion) J22 is slit into small rolls so that the width in the TD direction is the sheet width of the final product of the half slit sheet. And rewinding (step C1). The width at this time is orthogonal to the direction in which the half slits are inserted in the subsequent process, and is performed in order to determine how many half slits are formed on one sheet. The dimension that restricts the number of strip-like individual adhesive-attached longitudinal groove seals in the case of the half-slit sheet J4 is the TD direction in J22. The roll roll J221 is more versatile as an intermediate stock. Because the light guide plate has many types of light incident surface lengths, the thickness of the individual strips with adhesive material corresponding to the thickness of the light incident surface is limited to some extent, so it corresponds to the light guide plate This is because the length to be determined can be determined in a later step.
Next, the longitudinal groove sheet roll small roll J221 with adhesive is cut in the TD direction with a single blade so that the length in the MD direction is the length of the long side of the sheet to be bonded to the light incident surface of the light guide plate. Thus, a longitudinal groove sheet J3 with an adhesive material is formed (step C2).
Finally, the longitudinally peeled sheet J3 with adhesive is cut off in the MD direction with a single blade so that the length in the TD direction is the length of the short side of the sheet bonded to the light incident surface of the light guide plate. The half slit which cuts to a longitudinal groove layer, a base material, and an adhesion layer is performed, and it is set as the half slit sheet J4 (process C3). At this time, in order to reliably divide the adhesive-attached longitudinal groove seal J5, the cross sections shown in FIGS . 161 , 162 , and 163, which will be described in detail later, that is, the heavy peeling separator has a certain degree of cut, however, it is divided. Don't do this.

(marking)
Since the adhesive-attached fluted seal J5 bonded to the light guide plate is an optical member, the transparency is high, and the light guide plate to which the adhesive-attached fluted seal J5 is bonded is distinguished from the non-bonded light guide plate. It is very difficult. For this reason, it is difficult to inspect the missing product in which the adhesive-attached longitudinal groove seal J5 is not bonded in the light guide plate manufacturing process. In addition, there is no alignment mark at the time of bonding, and some mark is necessary for automation even in manual work. For this reason, it is preferable to make a visible marking on the longitudinal groove seal J5 with adhesive according to the present invention.
As a position for marking, a position where the surface light source device can be easily set as a position that does not affect optically, for example, a position described in a half slit sheet J41 with marking shown in FIG. 156 is preferable. In addition, as shown in the figure, the half slit sheet J41 with marking is illustrated as being marked at two places on both sides, but if necessary, one marked at one place, Marking may be performed near the center of the half slit sheet J41 with marking.

(Method of marking from the roll at the same time as sheeting)
A method of adding marking using the above-described step C2 will be described with reference to FIG .
The pressure-sensitive adhesive-equipped longitudinal groove sheet roll small roll J221 manufactured in step C1 is unwound so that the longitudinal groove layer formed in the inner winding becomes front. Then, using the marking head, one line is drawn in the TD direction, the roll is further fed out, and the second line is drawn (step C2-1). As a result, a line is drawn in the TD direction on both sides of the scheduled cutting position. In FIG. 154 , only one head is illustrated, but if two heads are used, two lines can be drawn simultaneously, and the head can be designed so that the head can also move in the roll feeding direction. In this case, it is not necessary to work while successively stopping the feeding of the roll, and the machining speed can be increased. However, if all of them are realized, the apparatus becomes large and expensive. Therefore, it is preferable to design the apparatus according to the production amount.
Next, the marking-equipped longitudinal groove sheet J31 is manufactured by cutting between the two markings in the TD direction with a single blade (step C2-2).
When cutting, make sure to insert a blade between the markings, and to minimize the influence of marking as a surface light source device (optical interference such as blocking or coloring the LED light as a point light source) Therefore, the marking position is preferably 0 mm or more and 20 mm or less, more preferably 0.5 mm or more and 10 mm or less, and most preferably 1 mm or more and 5 mm or less from the end of the longitudinal groove sheet J31 with marking. In this way, it is possible to place a marking on the edge where the LED does not exist when a single longitudinal groove seal J5 with a dressing material is pasted on the light incident surface, and when a plurality of sheets are pasted, the marking position is Optical interference can be suppressed by being between LED and adjacent LED in a surface light source device.

(Marking type)
Further, as a method for preventing the optical interference, the marking color is preferably black or gray. Accordingly, it is possible to prevent the light entering the light guide plate from the LED from being colored. The marking line thickness is preferably 50 μm to 2 mm, more preferably 100 μm to 1 mm, and most preferably 200 μm to 500 μm. By setting the marking line thickness within this range, it has been confirmed that the optical interference can be suppressed to the minimum while the function as a visual mark is sufficiently exhibited. In this case, even if the marking is on the surface facing the LED when the surface light source device is obtained, good quality can be ensured.
As a marking method, laser, ink jet, stamp roller, pen, and the like can be considered. In this production example, ink jet is suggested. As the ink material for inkjet, a dye system or a pigment system can be selected. However, in consideration of bleeding, the pigment system is often preferable. Moreover, water, an organic solvent (MEK, ethanol) etc. can be considered as a solvent. In the case of water, since there is no volatile substance, it is effective as a countermeasure against volatile organic compound VOC (Volatile Organic Compounds). If the organic solvent is taken into consideration for VOC countermeasures, the drying time is fast, so that the processing time can be shortened, and the organic solvent can be properly used as necessary.

(Marking for single sheet)
Moreover, it may be difficult to perform marking from the state of a roll by some processing methods, such as the above-mentioned manufacturing method B and the manufacturing method D mentioned later. FIG. 159 illustrates the marking method in that case. In step D3, sheets to be marked are sequentially sent out toward the marking head, and marking is performed on both ends of the sheet. The object of marking shown is the slit slit peeled half-slit longitudinal groove sheet (sheet) J42, but this device can mark the longitudinal groove sheet J3 with adhesive, the half-slit sheet J4, etc. as necessary. Can also be used. Various combinations of the processing steps are possible, and the fifth invention of the specification is not limited only to the processing flow shown in the manufacturing example.
In addition, as a marking method for a single sheet, a manual pen method can be used by using a jig or the like (a ruler, a mask, etc.) for aligning positions. When the production volume is small, it is possible to select manual operation.

(Half slit processing method C3 and B3 to a single wafer sheet)
A method for forming the half slit sheet J41 with marking by half slitting the longitudinal groove sheet J31 with marking manufactured in the process B2 of the manufacturing method B or the process C2 of the manufacturing method C will be described with reference to FIG .
The flute sheet J31 with marking manufactured in the process C2 or the flute sheet J31 with marking that has undergone the marking processing on the single wafer through the process B2 is peeled off from the feed stage on the front and back sides. Set to be a separator. The flute sheet with marking J31 is fed to the place where it is placed under the single blade on the feed stage, and the depth from which the heavy peel separator does not break while reaching the heavy peel separator to the width corresponding to the thickness of the light guide plate Then, a half slit sheet (sheet) J41 with marking can be manufactured.

(Slit white peeling process) Process C4
At this time, one sheet of adhesive-attached fluted seal J5 (hereinafter also referred to as "strip") made by the first slit and a strip made by the last slit are sent out to one fluted sheet J31 with marking. Since it is influenced not only by the feed accuracy of the stage but also by the setting position accuracy of the longitudinal groove sheet J31 with marking, it is not easy to make the width to maintain the optical performance corresponding to the thickness of the light guide plate. Therefore, FIG. 156 illustrates a method of removing strips at both ends of the half slit sheet with marking (sheet) J41.
The technique is generally performed manually, but can be mechanized and peeled off. In this way, the half slit sheet (sheet) J43 with the marking slit peeled off can be manufactured. This form is packed in a plurality of bags and cardboard packed, and transported to a step of bonding to the light incident surface of the light guide plate or sold to a manufacturer for bonding to the light incident surface of the light guide plate.

(Number of strips at half slit)
When half slits are inserted in the process as shown in FIG. 155 , the number of half slits increases because the strip is driven in the slit starting direction (left direction in FIG. 155 ) on the sheet by the thickness of the blade . When coming, the strip may float greatly from the heavy release separator, or the strip may ride on the adjacent strip. In addition, it is better that the number of strips per sheet is larger in consideration of packing efficiency. From the above two restrictions, the number of strips on the slit slit peeled half slit sheet (sheet) J41 or the marking slit slit half peel sheet (sheet) J43 is preferably 10 or more and 100 or less, 25 The number is more preferably 75 or more and 75 or less, and 50 is the most preferable in the industry, which is a sharp number in view of inventory management.

(Slit white width)
The width of the slit white is set for the purpose of improving the accuracy of the strip width and for preventing the strip from being peeled off from the half slit sheet (sheet) J4 by friction or the like during packing or transportation. However, if the width of the slit white is made too large, the taking efficiency deteriorates. Considering such a problem, the width of the slit white needs to be about 0 mm or more and 20 mm or less, preferably 1 mm or more and 10 mm or less, more preferably 2 mm or more and 5 mm or less. Further, if the width of the strip is equal to the thickness of the corresponding light guide plate, it is preferable because it can easily be manufactured without changing the feed conditions of the feed stage of Figure 155. For example, a strip width of 2.8 mm is suitable for a 3 mm-thick light guide plate that is mainly used for televisions in the market. In this case, the slit white is about 3 mm ± 1.5 mm in consideration of processing accuracy. It is preferable to set.

(Manufacturing method D1 of half-slit small roll) Rotary die method As described above, the strip length that can exist as a product (various types of light incident surface of the light guide plate) is very many, and the thickness of the light guide plate Since some types are limited to some extent, if you keep the state of the small roll with half slit (half slit small roll J222) as an intermediate stock, you will receive an order for the required strip length size In this case, it will be possible to handle delivery in a very short period of time, which has a great industrial significance.
The methods described FIG 157. Unroll the fluted sheet roll small roll J221 with adhesive material and press the rotary blade provided with a cylinder-shaped blade over the circumference to insert the half slit while flowing the roll seamlessly (step D1-1). ). Thereafter, the slit white portion is removed from the end of the sheet (step D1-2). Thereafter, the longitudinal groove layer is taken up as an inner side, and a half slit small roll J222 can be manufactured (winding step).

(Half slit roll roll cutting method D2 and marking method D3)
A method of manufacturing a half slit sheet (sheet) J43 with a marking slit peeled off from the half slit roll J222 will be described.
As shown in FIG. 158 , the half slit small roll J222 is unwound and cut and sheeted according to the length of the light incident surface of the light guide plate with a single blade (process D2). A slit longitudinal groove sheet (sheet) J42 can be manufactured. Depending on the assembly process of the light guide plate, the marking may not be necessary. Therefore, it is preferable that a plurality of sheets are packed in this form and transported or sold.
Then, as illustrated in FIG. 159 , the half-slit longitudinal groove sheet (sheet) J42 that has been peeled off is set on the delivery stage with the longitudinal groove layer as the front and the heavy release separator layer as the back, and the stage feed In accordance with the above, a marking line is made near the edge of the sheet. In this way, a half slit sheet (sheet) J43 with a marking slit peeled off can be manufactured.

(Half slit sheet warping direction)
The half slit sheet J4 is finally manufactured on the premise that the longitudinal groove seal J5 with adhesive is individually peeled from the heavy release separator in the bonding step to the light incident surface of the light guide plate. FIG. 160 illustrates a preferred warp direction of the half slit sheet J4 assuming that.
In FIG. 160 , the longitudinal groove layer is set as the convex side so as to warp the convex side in a cross section perpendicular to the direction in which the half slit is formed. In this way, as shown in the enlarged cross-sectional view, it is possible to set a tendency for the plurality of adhesive-attached fluted seals J5 to be separated so as to be slightly opened. It is easy to peel off and is very suitable. In addition, it is possible to minimize the concern that the adhesive material may be re-welded (stringing failure) when exposed to a high temperature or the like with the slit surface of the adhesive material in contact.
This warpage can be controlled by the pressing depth using the slit depth inserted into the heavy release separator or the roll in each processing step.

(Slit depth reaching the heavy release separator)
So far, the method of performing half slitting by means such as a single blade or a rotary die has been exemplified. 161 illustrates a preferred depth J6 where the slit extends over the heavy release separator.
As shown in FIG. 161 , the slit direction is set substantially perpendicular to the ridge line of the longitudinal groove of the longitudinal groove layer and substantially perpendicular to the surface of the separator. In order to surely slit to the adhesive layer, it is preferable to insert slits J6 of 0 μm or more into the heavy release separator, and it is necessary to keep the heavy release separator to a depth at which it does not break. In consideration of the stable production in consideration of the accuracy of the half slitting apparatus and the strength at which the heavy release separator is not broken by handling or the like, the slit depth J6 reaching the heavy release separator is preferably 2 μm or more and less than half the thickness of the heavy release separator, More preferably, it is 5 μm or more and 25 μm or less.

(Slit and strip misalignment over heavy release separator)
162 and 163 exemplify a form in which the gap between the slit J6 and the strip J5 reaching the above-described heavy release separator is controlled.
In FIG. 162 , the left cross section of the sheet is manufactured so that the slit J6 extending to the heavy release separator and the strip J5 are largely displaced. In step B3 or step C3, this can be realized by inserting a half slit from the left in FIG. 162 and controlling the angle of the blade edge of the single blade. Specifically, there is a method of making the blade angle asymmetric. In this way, the longitudinal groove seal (strip) J5 with adhesive is removed from the heavy release separator by manufacturing the adhesive longitudinal groove seal (strip) J5 and the slit J6 extending to the heavy release separator. The risk of the heavy release separator breaking together when peeling individually is greatly reduced.
FIG. 163 shows an example of a suitable deviation when processing by the rotary die method D1 shown in FIG . Due to the nature of the rotary blade, the gap between the slit J6 and the strip J5 reaching the heavy release separator to some extent near the center is small . Is manufactured outside the gap. This can be realized by changing the angle of the rotary blade individually in the length direction of the cylinder.
Also, as shown in FIG. 162 and FIG. 163 , a plurality of adhesive-attached longitudinal groove seals can be produced by trying to manufacture the adhesive-attached longitudinal groove seal (strip) J5 and the slit J6 extending over the heavy release separator. (Stripes) It is possible to prevent the problem of riding on the J5 and to stabilize the entire manufacturing process.

(An alternative to marking)
In this production example, the description of the marking has been described above as a visible mark. Instead of the above, it is also possible to select a method in which a colored protective film is bonded to the entire surface or a part of the longitudinal groove surface and formed integrally with the adhesive longitudinal groove seal J5. The former applies heat to the light guide plate after bonding. The latter peels only the colored protective film after bonding the adhesive-attached longitudinal groove seal J5 on the light incident surface of the light guide plate. If these methods are used, no marking remains on the light incident surface.

  In this production example, the invention has been described by limiting to a specific form within the scope of the purpose of explaining the invention. However, the present invention is not limited to the configuration, and can be appropriately combined and changed.

(Adhesive material)
In the present production example, the adhesive layer has been described with a thickness of 25 μm. However, in the fifth specification, the present invention is not limited to this thickness. A thickness of 5 μm or more and 250 μm or less is suitable. If the thickness is too thin, problems such as reliability are likely to occur. However, a thicker adhesive layer may be selected because air may not enter easily in the bonding process to the light incident surface of the light guide plate. In consideration of the circumstances, it is more preferably 10 μm or more and 100 μm or less, and more preferably 20 μm or more and 60 μm or less.

(Heavy release separator)
In this production example, the heavy release separator has been described with PET having a thickness of 75 μm, but in the specification 5th invention, it is not limited to this thickness. The material can be selected as long as it is a film-like member such as PC, PP, TAC, COP, PS, PMMA, MS, paper, and resin-coated paper. Further, the thickness needs to be 10 μm or more in order to insert a half slit, but the upper limit depends on the cost and the thickness that can be wound. In consideration of the circumstances around this, 10 μm or more and 500 μm or less is realistic, 25 μm or more and 250 μm or less is preferable, and 35 μm or more and 100 μm or less is more preferable. Further, 37 μm, 50 μm, and 75 μm are most suitable from the generally available PET base materials in terms of production stability and cost.

(Vertical groove layer and vertical groove sheet roll)
In this production example, the longitudinal groove layer has been described as a UV-cured resin layer having a longitudinal groove having a thickness of 15 μm, and the base material has been described as having a thickness of 125 μm of PET. It is not something. A transfer method using a thermosetting resin, a thermoplastic resin, or the like can be selected as the longitudinal groove layer, and optical materials such as PC, PP, TAC, COP, PS, PMMA, and MS can be used as the base material. Any film-like member having transparency that can be used for applications can be selected. As for the thickness of the base material, it can be implemented if it has a thickness of 10 μm or more. However, if it is too thin, handling at the time of bonding to the light incident surface of the light guide plate is poor, and workability is poor. This is not preferable because the risk of boarding increases. Therefore, in consideration of cost and performance, the thickness is preferably 25 μm or more and 250 μm or less, more preferably 38 μm or more and less than 150 μm, and most preferably 50 μm or more and 125 μm or less.

Specific embodiments of the half slit sheet that can be used in the fifth invention of the specification are as follows.
[1]
A half slit sheet in which a plurality of strip-like optical films integrated with an adhesive material are formed on a separator film,
On the surface of the optical film, there are a plurality of recesses or projections having an anisotropic shape that is long in the direction perpendicular to the side of any of the half slit sheets, or the bottom or bottom of the recess or projection. The back surface side of the optical film layer is substantially flat and an adhesive layer is integrally formed, and the separator film faces the surface facing the plane and the adhesive layer so that the adhesive layer can be easily peeled off. The optical film layer and the adhesive layer are cut in parallel with substantially the same width so as to form a plurality of strips on the separator film, and the cut direction is different from the plurality of recesses or projections. Half slit sheet that is oriented perpendicular to the long axis of the isotropic shape.
[2]
The half slit sheet according to [1], wherein at least one marking is applied to all of the plurality of strip-shaped optical films.
[3]
The half slit sheet according to the above [2], wherein the marking is applied in a line shape, and the thickness of the line is in the range of 50 μm to 2 mm.
[4]
The half slit sheet according to [2] or [3], wherein the marking is applied in a range of 1 mm to 5 mm from a short side end of the plurality of strip-shaped optical films.
[5]
The half slit sheet according to any one of [2] to [4], wherein the color of the marking is black or gray.
[6]
The size of the short side of the plurality of strip-shaped optical films is larger than the portion of the separator films on which the plurality of strip-shaped optical films are placed, and the separator film is set to have a protruding portion. The half slit sheet according to any one of the above [1] to [5], wherein
[7]
The half slit sheet according to [6], wherein a protruding portion of the separator film is set in a range of 1 mm to 5 mm.
[8]
Any one of the above [1] to [7], wherein the separator film has partial slits having a depth of 2 μm or more and half or less of the thickness of the separator film, the number of the plurality of strip-like optical films plus one. The half slit sheet according to crab.
[9]
The half slit sheet according to [8], wherein the position of the partial slit in the separator film is partially or entirely deviated from the position of the boundary between the strip-shaped optical films.
[10]
The half slit sheet according to [9], wherein the shift increases as the distance increases with the strip-shaped optical film near the center in the plane of the half-slit sheet or the strip-shaped optical film near either end.
[11]
Any one of the above [1] to [10], wherein the cross-section in the short side direction of the strip-shaped optical film warps the surface on which the strip-shaped optical film is placed, or is warped on the convex. The described half slit sheet.
[12]
The half slit sheet according to any one of [1] to [11], wherein the plurality of concave portions or convex portions having the anisotropic shape has a longitudinal groove structure.
[13]
The manufacturing method of the light-guide plate which bonds the strip-shaped optical film peeled from the half slit sheet in any one of said [1]-[12] to the light-incident surface at least 1 sheet.
[14]
The television receiver which has a light-guide plate as described in said [13].
[15]
A surface light source device having the light guide plate according to [13].

Hereinafter, a specific production example will be described.
The present invention is not limited to the above-described embodiment and the following manufacturing examples, and can be implemented with various modifications.
For example, the material, arrangement, shape, and the like of the members in the manufacturing examples are illustrative and can be implemented with appropriate changes. Further, the television receiver and the surface light source device can be configured by appropriately combining the configurations shown in the manufacturing examples. In addition, various modifications can be made without departing from the scope of the present invention.

<Production Example A>

[Production Example A-1]
The light incident surface is a mirror surface, and light scattering processing is uniformly applied to the opposite surface (circular diffusive dots made of diffusing beads and a binder having a diameter of 0.8 mm to 1.3 mm have a pitch of 2.55 mm × 1.5 mm. In a staggered arrangement (in a triangular lattice pattern), at the same distance from the end on the light incident surface side, the diameters of the dots in the partial area facing the LED and the dots in the partial area facing the LED are the same. (With a uniform dot density) light guide plate model (material: polymethyl methacrylate, thickness: 3.0 mm, width: 500 mm, length: 100 mm), LED (light emitting surface size: 4.5 mm) (Width direction) × 2.5 mm (thickness direction, 10 LEDs) are arranged along the light incident surface so that the arrangement pitch P is 27.5 mm, and a (light ray tracing simulation model of the surface light source device is produced. Shi It was.
A measurement model similar to the measurement detection model of a two-dimensional color luminance meter typified by Konica Minolta CA2000A is produced, and 7 mm inside (P / G = 3. Light Tools (Optical Research Associates) version 7. The luminance distribution when viewed from the front direction (V = 0 °, H = 0 °) in the direction equivalent to 3.93) is observed in a direction parallel to the light incident surface. 1 was used for calculation. [Production Example A-2]
The light guide plate model is subjected to light scattering processing on the opposite surface as shown in FIG. 19 (ρ = 18.0% to 45.0 in the vicinity of the light incident surface (region near 7 mm inside (G = 7 mm) from the light incident surface side end). % In the central portion of the facing surface, except that it is uniform at ρ = 8%). The luminance distribution when observed from the front direction (V = 0 °, H = 0 °) was calculated.
[Production Example A-3]
The light guide plate model is a transparent double-sided polyethylene terephthalate film with an average thickness of 125 μm on which the groove structure having the surface profile shown in FIG. 2 (average pitch: about 6 μm, average depth: about 4 μm) is formed. From the front direction (V = 0 °, H = 0 °) 7 mm inward from the light incident surface side end of the light exit surface, except that the adhesive sheet was used for attachment. The luminance distribution when observed was calculated.
[Production Example A-4]
The light guide plate model is a transparent double-sided polyethylene terephthalate film with an average thickness of 125 μm on which the groove structure having the surface profile shown in FIG. 2 (average pitch: about 6 μm, average depth: about 4 μm) is formed. Adhering using an adhesive sheet, the light scattering processing of the opposing surface is shown in FIG. 19 (ρ = 18.0% in the vicinity of the light incident surface (region near 7 mm inside (G = 7 mm) from the light incident surface side end). ˜45.0%, variation is uniform at ρ = 8% in the central portion of the opposing surface), in the same manner as in Production Example A-1, on the light incident surface side end of the light exit surface The luminance distribution when observed from the front direction (V = 0 °, H = 0 °) inside 7 mm from the top was calculated.

The luminance distribution when observed from the front direction (V = 0 °, H = 0 °) 7 mm inside from the light incident surface side end of the light exit surface of the surface light source devices of Production Examples A-1 to A-4 is shown in FIG. The standard deviation (SD value) is shown in FIG. 21 and Table A-1.
In FIG. 20, the vertical axis represents luminance, and the horizontal axis represents the position in the direction parallel to the light incident surface on the light exit surface. Further, in FIG. 21, the chain line indicates an S.D. allowable for use in an image display device. D. Value (0.2), and the alternate long and short dash line is sufficient S.D. D. The value (0.1) is shown.

[Table A-1]

In the surface light source device of Production Example A-1, the luminance is not constant and a hot spot (maximum portion) appears, and even in the surface light source devices of Production Examples A-2 and 3, this luminance unevenness cannot be resolved. . That is, the light configured such that the light scattering degree of the partial area directly facing the point light source is lower than the light scattering degree of the partial area directly facing the portion between the point light source and the light incident surface of the opposing surface. In Production Example A-2 subjected to scattering processing, the luminance of the portion directly facing the LEDs could be suppressed, but the luminance of the portion directly facing between the LEDs could not be increased. On the other hand, in Production Example A-3 in which a groove structure was formed on the light incident surface of the light guide plate, the luminance of the portion directly facing between the LEDs could be suppressed to some extent, and the luminance of the portion corresponding to between the LEDs could be increased. It wasn't.
On the other hand, in the surface light source device of Production Example A-4, the luminance was almost constant regardless of the location, and no hot spot appeared.
The surface light source device of Production Example A-4 is not provided with a frame and the light emitting area is not defined. However, in order to achieve a display device with a narrow frame that is currently in trend, G (light incident surface) In the surface light source device (P = 27.5 mm) of Production Example A-4, 7 mm from the light incident surface side end of the light exit surface is required. S. of luminance when observed from the front direction on the inside. D. The value was very low at 0.04. Therefore, even if the LED array pitch is expanded to about 30 mm under the condition of G = 7 mm, that is, P / G> 4, it is acceptable for use in an image display device as long as it is observed from the front direction. S. D. The value (0.2) is considered to be obtained. However, in the surface light source device of Production Example A-4, the light scattering degree of the partial region directly facing the point light source is 7 mm inside (area corresponding to the light emitting area) from the light incident surface side end of the opposing surface of the light guide plate. Since it is lower than the light scattering degree of the partial region directly facing the portion between the point light source and the point light source (ρ1 = 18.0%, ρ2 = 45.0%), the oblique direction (V = 0 °, H = 20 °) ) Of the luminance as measured from D. The calculated value was 0.05 or more. Therefore, when the LED array pitch is widened, the allowable S.D. D. The value may not be obtained.

[Production Example A-5]
A polyethylene terephthalate film having an average thickness of 125 μm and having a groove structure having the surface profile (average pitch: about 6 μm, average depth: about 4 μm) shown in FIG. The light scattering processing shown in FIG. 38 was applied to the opposite surface (circular diffusive dots having a diameter of 0.8 mm to 1.3 mm made of diffusing beads and a binder in a staggered arrangement (in a triangular lattice shape). ), Ρ = 20 to 60% in a partial region directly facing between the point light source and the point light source of 1 to 4 mm (light shielding portion, region B in the vicinity of the light incident surface) from the end portion on the light incident surface side, 4 mm or more from the light incident surface side end portion (non-light shielding portion, region A) so that ρ = 7 to 20% in the light incident surface side end portion 4 to 6 mm (light shielding portion (boundary area), region A). ) Is set so that ρ = 8%. A) Light guide plate (material: polymethyl methacrylate, thickness: 3.0 mm, width: 409 mm, length: 721 mm), LED (light emitting surface size 5.0 mm (width direction) × 3.0 mm (thickness direction), LED (Several 36) were arranged along the light incident surface so that the arrangement pitch P was 19.2 mm.
On top of this, from the light guide plate side, a diffusion sheet (DS), a prism sheet (having a groove structure having a ridge line parallel to the light incident surface on which the LED is disposed on the surface), and a reflective polarizing sheet (manufactured by 3M) DBEF) is laminated in this order, and a frame having an opening of 395 mm × 700 mm in a size that sufficiently covers the light guide plate and the LED is arranged on the light guide plate so as to face the light output surface side of the light guide plate. A light source device was produced.
Using a secondary color luminance meter (CA2000A manufactured by Konica Minolta), the luminance is measured from the front direction (V = 0 °, H = 0 °) of the light emitting surface, and the standard deviation (SD value) of the luminance of the light emitting surface is calculated. Asked.
The results are shown in FIG . The luminance S.D. D. The value was as very low as 0.02 or less in P / G = 1 to 2.6 (G is a distance (mm) from the light incident surface).

Further, when the light emitting surface is viewed from an oblique direction (V (Vertical) = 45 ° or H (Horizontal) = 20 °) (the measurement direction of the luminance meter is V = 45 ° or H = 20 with respect to the front surface of the light emitting surface). (Measured at an angle of inclination), the luminance S.D. D. Values are shown in Table A-2. Here, H and V indicate the inclination angles of the luminance meter, and the inclination angles in directions parallel to the light incident surface (inclination angles rotated around an axis perpendicular to the light incident surface), the light incident surface, respectively. Is a direction in which a positive value falls at the center of the light emitting area or the display area at an inclination angle in a direction perpendicular to (an inclination angle rotated about an axis parallel to the light incident surface).
In the surface light source device of Production Example A-5, not only from the front, but also luminance unevenness when viewing the light exit surface from an oblique direction was reduced. In addition to the measurement using a two-dimensional color luminance meter, the luminance unevenness is also evaluated in parallel with the visual evaluation. D. It was confirmed that the result was the same as the result of the value.

[Table A-2]

[Production Example A-6]
The light scattering processing of the opposing surface of the light guide plate is as shown in FIG. 40 (circular diffusive dots having a diameter of 0.8 mm to 1.3 mm made of diffusing beads and a binder are arranged in a staggered manner (in a triangular lattice shape). Ρ = 20 to 60% in the partial region facing directly between the point light source and the point light source of 1.5 to 4.5 mm (light shielding portion, region B in the vicinity of the light incident surface) from the light incident surface side end. In addition, 4.5 mm to 6 mm from the light incident surface side end (light shielding portion (boundary area), region A) is 6 mm or more from the light incident surface side end (non-light shielding) so that ρ = 10 to 13%. In the part, region A), ρ = 8 to 9% is provided, and when compared with the light scattering processing in Production Example A-5, between the partial region directly facing the point light source in the boundary area and between the point light source and the point light source Except for the small difference in the light scattering degree of the partial region directly facing to the same as in Production Example A-5, It was observed uneven brightness of the light plane.
The luminance unevenness was observed in Production Example A-5 when observed from either the front (V = H = 0 °) or the oblique direction (V = 0 °, H = 20 °, V = 45 °, H = 0 °). It was smaller than that.

[Production Example A-7]
In the surface light source device of Production Example A-6, a display panel having a configuration similar to that shown in FIG. 35 (a size in which the outer frame of the light shielding frame sufficiently covers the light guide plate, and a display area 392.4 mm × 696.4 mm). ) Was arranged so as to face the light exit surface side of the light guide plate, and a display device was manufactured, and luminance unevenness in the display area was observed.
The luminance unevenness in the display area is a manufacturing example even when observed from either the front (V = H = 0 °) or the oblique direction (V = 0 °, H = 20 °, V = 45 °, H = 0 °). It was smaller than that of A-5.

[Production Example A-11]
A polyethylene terephthalate film having an average thickness of 125 μm and having a groove structure having the surface profile shown in FIG. 25 is attached to the light incident surface using a transparent double-sided adhesive sheet, and the light scattering shown in FIG. 41 is applied to the opposite surface . Processed (circular diffusive dots of 0.8 mm to 1.3 mm in diameter consisting of diffusing beads and a binder in a staggered arrangement (in a triangular lattice shape), 1.5 to 3 from the light incident side end .5 mm (light-shielding portion, region B in the vicinity of the light incident surface) of the partial region directly facing between the point light source and the light source surface side end portion so that ρ = 20 to 60%. 5 to 6 mm (light-shielding part (boundary area), region A) is ρ = 10%, and ρ = 9% is 6 mm or less (non-light-shielding part, region A) from the light incident surface side end. Provided to be 3.5 to 4 from the end of the light incident surface. Light scattering processing is not provided in other regions including 5 mm (light-shielding portion, region C)) Light guide plate (material: polymethyl methacrylate, thickness: 3.0 mm, width: 409 mm, length: 721 mm), LED (Light emitting surface size 5.0 mm (width direction) × 3.0 mm (thickness direction), 36 LEDs) was arranged along the light incident surface so that the arrangement pitch P was 19.2 mm.
On this, from the light guide plate side, a diffusion sheet (DS) / prism sheet (having a groove structure having a ridge line perpendicular to the light incident surface on which the LED is disposed on the surface) / prism sheet (the LED is disposed) (A groove structure having a ridge line parallel to the light incident surface is provided on the surface) / diffusion sheet (DS) is laminated in this order, and further, the outer shape sufficiently covers the light guide plate and the LED and is 395 mm × A frame having an opening of 700 mm is disposed so as to face the light exit surface side of the light guide plate, a surface light source device is manufactured, and the luminance distribution S.D. of the light exit surface is manufactured in the same manner as in Production Example A-5. D. The value was determined.
Further, a liquid crystal display panel is laminated on the surface light source device, and the luminance distribution S.D. D. Values were also determined.
The results are shown in FIG .

  The luminance unevenness is 0.01 or less in the front (V = H = 0 °) and 0.01 or less in the oblique direction (V = 45 °, H = 0 °), and the oblique direction (V = 0 °, H = 20 °), which was 0.01 or less, even when observed from any of these, it was even smaller than that of Production Example A-6.

In Production Example A-11, in addition to the light scattering processing of the light exit surface, there is a prism sheet (having a groove structure on the surface having a ridge line perpendicular to the light entrance surface on which the LED is disposed) as an optical sheet. The brightness unevenness reduction effect can be obtained very strongly, and when viewed from an oblique direction by adding a prism sheet (having a groove structure having a ridge line parallel to the light incident surface on which the LED is arranged) on the surface Further improvement in luminance unevenness was also obtained.
Moreover, the light scattering process provided in the light guide plate was not visually recognized by the diffusion sheet disposed between the light guide plate and the prism sheet.

[Production Example A-12]
The light scattering processing of the opposite surface of the light guide plate was as follows (not shown) (circular diffusive dots made of diffusing beads and a binder having a diameter of 0.8 mm to 1.3 mm in a staggered arrangement (triangular lattice) ) = Ρ = 50 in a partial region directly facing a portion between the point light source and the point light source of 1.5 to 3.5 mm (light shielding portion, region B in the vicinity of the light incident surface) from the light incident surface side end. In the range from 4.5 to 6 mm from the light incident surface side end so as to be ˜100% (light shielding portion (boundary area), region A), from the light incident surface side end so that ρ = 10%. After 6 mm (non-light-shielding part, area A), ρ = 9% is provided, and other areas including 3.5 to 4.5 mm (light-shielding part, area C) from the end of the light incident surface are provided. Except that light scattering processing is not provided), luminance unevenness on the light exit surface was observed in the same manner as in Production Example A-5.
Even when the luminance unevenness was observed from either the front or the oblique direction, a quality better than that of Production Example A-6 was obtained.

  In Production Example A-12, since the prism sheet used was only one sheet having a groove structure having a ridge line parallel to the light incident surface on which the LEDs are arranged, the luminance unevenness reducing effect is Although not as good as in Production Example A-11, substantially the same effect was obtained.

[Production Example A-13]
The LED arrangement pitch P was changed to 13.4 mm, and the light scattering processing of the opposing surface of the light guide plate was as follows (not shown) (with a diameter of 0.8 mm to 1.3 mm consisting of diffusion beads and a binder) The circular diffusive dots are arranged in a staggered arrangement (in a triangular lattice pattern) with a point light source and a point light source of 1.5 to 3.5 mm (light shielding portion, region B in the vicinity of the light incident surface) from the light incident surface side end. In the partial region directly facing the intermediate portion (width 4.5 mm), 4.5 to 6 mm (light-shielding portion (boundary area), region A) from the light incident surface side end so that ρ = 50 to 100%. Is provided so that ρ = 9% after 6 mm from the light incident surface side end portion (non-light-shielding portion, region A) so that ρ = 10%, and light scattering processing is performed in other regions. In the same manner as in Production Example A-5, the luminance distribution S.D. D. The value was determined.
Even when the luminance unevenness was observed from either the front or the oblique direction, a quality better than that of Production Example A-6 was obtained.
The results are shown in FIG .

  In Production Example A-13, since the prism sheet used was only one sheet having a groove structure having a ridge line parallel to the light incident surface on which the LEDs are arranged, the luminance unevenness reducing effect is Although not as good as in Production Example A-11, the pitch between point light sources was suppressed more than in Production Example A-11, and almost the same effect was obtained.

[Production Examples A-14 to 16]
In the 32ML10 TV receiver manufactured by Mitsubishi Electric Corporation, the arrangement pitch of the LEDs in the surface light source device is changed to 19.2 mm, and the light guide plate is subjected to light scattering processing shown in Table A-3 on the opposite surface ( FIG. 44 or FIG. 41 ), and instead of the reflection sheet attached to the side surface (side surface perpendicular to the light incident surface) shown in Table A-3 (FIGS. 54 to 56 ), Production Example A-14 Television receivers (a) to (d) were produced.
A transparent double-sided adhesive sheet (manufactured by Panac Co., Ltd.) having a UV curable resin layer having a plurality of recesses (FWHM: 83 (width) × 3 (length)) shown in FIG. Television receivers of Production Examples A-15 (a) to (d) were produced in the same manner as in Production Example A-14, except that bonding was performed using PD-S1).
On the light incident surface of the light guide plate, a polyethylene terephthalate film having a prism with apex angle R (pitch: about 50 μm: the ridge line direction of the prism coincides with the thickness direction of the light guide plate) on the surface is a transparent double-sided adhesive sheet (PD-made by Panac) Except having bonded together using S1), it carried out similarly to manufacture example A-14, and produced the television receiver of manufacture example A-16 (a)-(d).
For these television receivers, the in-plane average luminance of the secondary color luminance meter (CA2000A manufactured by Konica Minolta) and the in-plane average chromaticity x and y were measured through a liquid crystal panel. The (a) no unevenness was used as a reference, the luminance was relative luminance%, and the chromaticities x and y were arranged as differences Δx and Δy from the reference. The results are shown in Tables A-3 to 5 below.

[Table A-3]

[Table A-4]

[Table A-5]

In Production Examples A-14 to 16, the light scattering pattern of the opposing surface of the light guide plate may be the same as that shown in FIG. 44 or the one shown in FIG. As long as the arrangement of the reflection sheet and the shape of the light incident surface) were the same, there was no significant difference in luminance and chromaticity.
Moreover, when it has a several recessed part or convex part in the light-incidence surface of a light-guide plate (manufacture example A-15), in-plane average compared with the case where a light-incidence surface is a mirror surface (manufacture example A-14) Although the brightness tends to decrease, the average brightness could be recovered by applying a reflective sheet to the entire side surface of the light guide plate (arrangement of FIG. 54 ). Also, when pasting the reflecting sheet on the side surface of the light guide plate part, better to stick to the vicinity of the light incident surface as in FIG. 56, the average in-plane as compared to the case where put on the center as shown in FIG. 55 The brightness could be increased.

[reference]
In a system in which the pitch of LEDs is denser (P = 10.0 mm), light scattering processing is applied to a region A that covers at least a non-light-shielding portion that is not shielded by a light-shielding frame on the light exit surface and / or the opposing surface of the light guide plate. In addition, in the region B in the vicinity of the light incident surface of the light shielding part that is shielded by the light shielding frame, the light scattering degree of the partial region that directly faces the point light source is a partial region that faces the part between the point light source and the point light source. In a region C that is subjected to light scattering processing configured to be lower than the light scattering degree and is sandwiched between the region A and the region B, at least a partial region that faces at least a portion between the point light source and the point light source If light scattering processing is not provided in the case, even if a plurality of concave portions or convex portions are not formed on the light incident surface (even if the light incident surface is a substantially mirror surface), a certain degree of luminance unevenness reduction effect is obtained. can get.
Conventionally, in the region A, a light guide plate has been proposed in which the light scattering degree of the partial region facing the point light source is higher than the partial region facing the point light source, but the oblique quality in the H direction is particularly poor. The optimum quality for TV etc. could not be obtained. Further, in the region A, the partial region directly facing the point light source and the partial region directly facing between the point light source and the point light source have the same light scattering degree, and in the region B, the portion facing directly between the point light source and the point light source. It is a specification in which light scattering processing is performed only on the region, and even when the region C is not provided and the region A and the region B are in contact, the quality in the H direction is not sufficient.
Luminance unevenness on the light exit surface was observed in the same manner as in Production Example A-11 except that a film having a groove structure was not pasted on the light entrance surface of the light guide plate and the LED array pitch P was 10 mm.
Even when observed from the front or oblique direction, the luminance unevenness is a light guide plate in which a film having a groove structure formed on the light incident surface is not pasted by light scattering processing as shown in FIG. Compared to a light guide plate that does not have a groove structure on the light surface and is not subjected to light scattering processing corresponding to the position of the point light source).

<Production Example B>

(Diffusion sheet)
In Production Example B, using a master mold having a predetermined speckle pattern, the photopolymerizable resin composition is filled between the substrate and the master mold, and cured through ultraviolet irradiation through the substrate. Next, it was made to peel between the master type | mold and the resin layer which consists of hardened | cured material of a photopolymerizable resin composition, and the resin layer which has an uneven structure was formed in the single side | surface of a base material.
Production Examples B-1 to 6, 9, and 10 all used the same master mold.
In addition, Production Examples B-7 and 8 are different from the master type in which the diffusion angle differs depending on the projection area immediately above the light source and the projection area between the light sources, as will be described later, and Production Examples B-7, 8 A master mold with a different distribution shape was used.
In the ultraviolet irradiation, irradiation was performed using a high-pressure mercury lamp with an irradiation condition of 250 mJ / cm ² .
The thickness of the resin layer was 15 μm.

(Various optical sheets used in Production Example B)
Reflective sheet: White reflective sheet made of polyester resin (hereinafter abbreviated as “RS”, trade name: Lumirror E6SL, manufactured by Toray)
Diffusion plate: Diffusion plate made of polystyrene and having a thickness of 1.5 mm and a diffusing agent concentration of 13000 ppm (hereinafter abbreviated as “DP”, trade name DSF60, manufactured by Asahi Kasei E-Materials)
Surface-shaped diffusion sheet: An optical sheet (hereinafter abbreviated as “MLF”) in which a hemispherical lens is shaped with a UV curable resin on a PET substrate having a thickness of 250 μm. Product name: PTR-733, manufactured by Shinfa Intertec )
Optical sheet having an arrayed prism array structure: an optical sheet in which a prism array having a vertex angle of 90 ° and a pitch of 50 μm is formed by a UV curable resin on a PET substrate having a thickness of 250 μm (hereinafter referred to as “prism sheet”) (Product name: BEF-III, 3M)
Reflective polarizing sheet: reflective polarizing sheet (hereinafter abbreviated as “DBEF”, trade name DBEF, manufactured by 3M)
Were used respectively.

(Light source and light source unit used in Production Example B)
As a light source of the light source unit, a white LED light source (trade name: LM6-EWN1-03-N3 manufactured by CREE) having a 3.5 mm square and a height of 2.0 mm was used.
The LEDs are arranged in a 133 pattern in a pattern as shown in FIG. 73 to produce a light source unit.

Hereinafter, a method for measuring characteristics in Production Example B will be described.
(Diffusion angle)
The diffusion angle is made incident from the surface of the diffusion sheet having a fine concavo-convex structure, and manufactured by Photon Co., Ltd. Goniometric Radiometers Real-Time Far-Field Angular Profiles Model LD89.
Measured at 00.
In Production Example B below, for example, when the diffusion angle is expressed as 5 °, it indicates that the FWHM (diffusion angle) of light in any direction is also 5 °.
For the diffusion angle distribution, FWHM was measured at intervals of 1 mm with respect to the x-axis direction and / or the y-axis direction of the diffusion sheet, and a diffusion angle distribution diagram was created.

(Brightness and brightness unevenness)
The luminance was determined by using a two-dimensional color luminance meter (CA2000) manufactured by Konica Minolta, installed 70 cm away from the light source unit, and an average luminance value measured in a range of 120 mm × 120 mm at the center of the light source unit as luminance.
The luminance unevenness was an average value of values calculated in two directions of the x-axis direction and the y-axis direction.
First, an average luminance value in the x-axis (120 mm) direction is obtained, and in the y-axis direction, luminance is obtained as a standard deviation of a value obtained by dividing the luminance value at each point by the average luminance value for ± 15.2 mm from each point. I asked for unevenness.
Similarly, the average luminance value in the y-axis (120 mm) direction is obtained, and the standard deviation of the value obtained by dividing the luminance value at each point by the luminance average value for ± 20.8 mm from each point in the x-axis direction. Luminance unevenness was obtained.
Finally, a value obtained by averaging the standard deviation in the x-axis direction and the standard deviation in the y-axis direction (hereinafter, <Production Example B>
Inside, it is expressed as “SD”. ) Is the luminance unevenness of the light source unit.
Since the LED light source is a point light source, as shown in FIG. 58 (b), on the straight line distance between adjacent light sources, such as is maximum line (broken line in FIG. 58 (b)), considering the distribution of the diffusion angle .
The brightness unevenness was measured from the normal direction to the screen.
Here, the criteria for determining the luminance unevenness were classified into two stages (◯, ×) as follows.
○: S. D. ≦ 0.005
X: 0.005 <S. D.

(Refractive index of resin layer)
The refractive index of the resin layer was measured by removing the resin layer having a thickness of 15 μm from the substrate and measuring only the resin layer with a refractometer MODEL 2 010 PRISM COUPLER (manufactured by Metricon).
The measurement results are shown in Table B-1 below for each resin used.

[Production Example B-1]
As shown in FIG. 70 (b), above the light source (LED) 12, a diffusion plate (DP) 14, a diffusion sheet 15, a prism sheet 17, a reflective polarizing sheet (DBEF) 18 of Production Example B-1, which will be described later, Were arranged in this order to obtain a light source unit of Production Example B-1.
The diffusion sheet 15 of Production Example B-1 is formed on one surface of a base material of a polyethylene terephthalate film (Cosmo Shine A4300, manufactured by Toyobo Co., Ltd., hereinafter referred to as “PET base material”) having a thickness of 250 μm. The resin layer (resin 1) which consists of a hardened | cured material of the photopolymerizable resin composition which has a composition shown to Table B-1 and Table B-2 is formed, and this resin layer has a speckle pattern by interference exposure on the surface. It has an irregular concavo-convex structure derived from
In Tables B-1 and B-2, (A-1) to (A-5) correspond to “(A): addition polymerizable monomer having at least one terminal ethylenically unsaturated group”. Among them, (A-1) corresponds to the compound represented by the above general formula (I). (B-1) corresponds to (B): a photopolymerization initiator.
This diffusion sheet 15 was used so that the concavo-convex structure surface was the light exit surface.
The diffusion angle (FWHM) of the diffusion sheet 15 of Production Example B-1 was 83 °.
Here, the distance h between the reflection sheet (RS) 13 and the light incident surface of the diffusion plate (DP) 14 was set to 21.0 mm.
The luminance unevenness in the light source unit of Production Example B-1 was calculated by the above method.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-2]
The photopolymerizable resin composition was changed to (Resin 2) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-2 was 85 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-3]
The photopolymerizable resin composition was changed to (Resin 3) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-3 was 90 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-4]
The photopolymerizable resin composition was changed to (Resin 4) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-4 was 80 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-5]
The photopolymerizable resin composition was changed to (Resin 5) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-5 was 87 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-6]
The photopolymerizable resin composition was changed to (Resin 6) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-6 was 86 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-7]
As shown in FIG. 70 (a), above the light source 12, a diffusion plate (DP) 14, a diffusion sheet 15 of Production Example B-7 to be described later, a surface shaping type diffusion sheet (MLF) 16, a surface shaping type. A diffusion sheet (MLF) 16 and a reflective polarizing sheet (DBEF) 18 were arranged in this order to constitute the light source unit of Production Example B-7.
The diffusion sheet of Production Example B-7 comprises a cured product of a photopolymerizable resin composition having a composition shown in Table B-1 and Table B-2 below on one surface of a PET substrate having a thickness of 250 μm. It has a resin layer (resin 1), and the resin layer has an irregular uneven structure derived from a speckle pattern by interference exposure on the surface.
In the diffusion sheet of Production Example B-7, the diffusion angle of the projection area of the light source is 83 °, the diffusion angle of the projection area of the intermediate point between the light source and the light source is 28 °, and the diffusion angle is as shown in FIG. changed.
In FIG. 74A , the horizontal axis indicates a predetermined position on the diffusion sheet surface, and the circles described in the horizontal axis indicate the position of the light source.
The diffusion sheet of Production Example B-7 was used so that the layer on which the irregular concavo-convex pattern shape was formed became the light exit surface.
Here, the distance h between the reflection sheet (RS) 13 and the light incident surface of the diffusion plate (DP) 14 was set to 19.0 mm.
The luminance unevenness in the light source unit of Production Example B-7 was calculated by the above method.
The evaluation results of the luminance unevenness are shown in Table B-3 below.
Moreover, all the measurement points distributed between the arithmetic mean value (Av1) of the diffusion angle peak value and the diffusion angle bottom value in the diffusion sheet of Production Example B-7, and the continuous diffusion angle peak value and the diffusion angle bottom value. Table B-3 below shows the arithmetic average value (Av2) of the diffusion angles.

[Production Example B-8]
As shown in FIG. 70 (a), a diffusion plate (DP) 14 above the light source 12, a diffusion sheet 15 of Production Example B-8, which will be described later, a surface-shaped diffusion sheet (MLF) 16, and a surface-shaped diffusion. The sheet (MLF) 16 and the reflective polarizing sheet (DBEF) 18 were arranged in this order to constitute the light source unit of Production Example B-8.
The diffusion sheet of Production Example B-8 is composed of a cured product of a photopolymerizable resin composition having a composition shown in Table B-1 and Table B-2 below on one surface of a PET substrate having a thickness of 250 μm. The resin layer (resin 1) was provided, and the resin layer had an irregular uneven structure derived from a speckle pattern by interference exposure on the surface.
In the diffusion sheet of Production Example B-8, the diffusion angle of the projection area of the light source is 83 °, the diffusion angle of the projection area of the intermediate point between the light source and the light source is 28 °, and the diffusion angle is as shown in FIG. changed.
The horizontal axis in FIG. 74 (b) indicates a predetermined position on the diffusion sheet surface, and the circles described in the horizontal axis indicate the position of the light source.
The diffusion sheet of Production Example B-8 was used so that the layer provided with the irregular concavo-convex pattern shape was the light exit surface.
Here, the distance h between the reflection sheet (RS) 13 and the light incident surface of the diffusion plate (DP) 14 was set to 17.0 mm.
The luminance unevenness in the light source unit of Production Example B-8 was calculated by the above method.
The evaluation results of the luminance unevenness are shown in Table B-3 below.
Further, all measurement points distributed between the arithmetic average value (Av1) of the diffusion angle peak value and the diffusion angle bottom value in the diffusion sheet of Production Example B-8, and the continuous diffusion angle peak value and the diffusion angle bottom value. Table B-3 below shows the arithmetic average value (Av2) of the diffusion angles.

[Production Example B-11]
The photopolymerizable resin composition was changed to (Resin 7) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-11 was 75 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Production Example B-12]
The photopolymerizable resin composition was changed to (Resin 8) in Table B-1 and Table B-2 below.
Other conditions were the same as in Production Example B-1, and a diffusion sheet was produced to obtain a light source unit.
The diffusion angle (FWHM) of the diffusion sheet of Production Example B-12 was 70 °.
The evaluation results of luminance unevenness are shown in Table B-3 below.

[Table B-1]

[Table B-2]

[Table B-3]

As shown in Table B-1, the diffusion sheets of Production Examples B-1 to B-6 are diffusion sheets having a resin layer having an uneven structure on the light exit surface of the diffusion sheet, and the refractive index of the resin layer is 1.55. To 1.70, and the resin is (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group: 70 to 99.9% by mass, (B) photopolymerization initiator: 0.1 A cured product of a photopolymerizable resin composition containing -30% by mass, wherein the (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group is represented by the general formula (I) Since the compound which has a structure represented is contained, the brightness nonuniformity reduction capability was favorable and it turned out that the distance between a light source and an optical sheet can be shortened.
Moreover, although it is usually difficult to obtain a diffusion sheet having a diffusion angle (FWHM) of 76 ° or more, if the above-mentioned photopolymerizable resin composition is used, the transfer rate is reduced due to curing shrinkage or the cured product is too hard. It has been found that it is possible to obtain a diffusion sheet that can be achieved without causing defects due to the above, and that has a good ability to reduce uneven brightness.

Moreover, since the diffusion angle of the diffusion sheet of Production Example B-7 periodically changes along a predetermined direction in the diffusion sheet surface, the luminance unevenness reduction ability is better, and the reflection sheet (RS) 13 and It was found that the distance h from the light incident surface of the diffusing plate (DP) 14, that is, the distance between the light source and the optical sheet can be further shortened.
Further, in the diffusion sheet of Production Example B-8, all the measurement points distributed between the diffusion angle peak value and the diffusion angle bottom value in which the arithmetic average value (Av1) of the diffusion angle peak value and the diffusion angle bottom value continues. Is larger than the arithmetic average value (Av2) of the diffusion angle, and thus the luminance unevenness reduction capability is very good, and the distance h between the reflection sheet (RS) 13 and the light incident surface of the diffusion plate (DP) 14, that is, the light source It was found that the distance between the optical sheet and the optical sheet can be further shortened.

<Production Example C>

[Production Example C-1]
The light incident surface is a mirror surface, and light scattering processing is uniformly applied to the opposite surface (circular diffusive dots made of diffusing beads and a binder having a diameter of 0.8 mm to 1.3 mm have a pitch of 2.55 mm × 1.5 mm. In a staggered arrangement (in a triangular lattice pattern), at the same distance from the end on the light incident surface side, the diameter of the dots in the area facing the LED and the dots in the area facing the LED are the same ( Light guide plate model (material: polymethyl methacrylate, thickness: 3.0 mm, width: 500 mm, length: 100 mm) provided on LED (light emitting surface size 4.5 mm (width)) Direction) × 2.5 mm (thickness direction, 10 LEDs) was prepared along a light incident surface so that a light tracing simulation model of a surface light source device was arranged so that the arrangement pitch P was 27.5 mm.
A measurement model similar to the measurement detection model of a two-dimensional color luminance meter typified by Konica Minolta CA2000A is produced, and 7 mm inside (P / G = (Corresponding to 3.93) was calculated using Light Tools (Optical Research Associates) version 7.1 over a direction parallel to the light incident surface.
[Production Example C-2]
FIG. 77 (ρ1 = 18.0%, ρ2 = 45.0% near the light incident surface (near 7 mm inside (G = 7 mm) near the light incident surface side end) of the light guide plate model . The brightness distribution 7 mm inside from the light incident surface side end of the light exit surface was calculated in the same manner as in Production Example C-1 except that the above was changed.
[Production Example C-3]
The light guide plate model is a transparent double-sided polyethylene terephthalate film with an average thickness of 125 μm on which the groove structure having the surface profile shown in FIG. 2 (average pitch: about 6 μm, average depth: about 4 μm) is formed. A luminance distribution 7 mm inward from the light incident surface side end of the light exit surface was calculated in the same manner as in Production Example C-1, except that the adhesive sheet was used.
[Production Example C-11]
The light guide plate model is a transparent double-sided polyethylene terephthalate film with an average thickness of 125 μm on which the groove structure having the surface profile shown in FIG. 2 (average pitch: about 6 μm, average depth: about 4 μm) is formed. Fig. 77 (ρ1 = 18.0%, ρ2 = in the vicinity of the light incident surface (near 7 mm from the light incident surface side end (G = 7 mm)) is applied using an adhesive sheet . 45.0%) A luminance distribution 7 mm inside from the light incident surface side end of the light exit surface was calculated in the same manner as in Production Example C-1.

FIG. 78 shows the luminance distribution 7 mm inside from the light incident surface side end of the light exit surface of the surface light source devices of Production Examples C-1 to C3 and 11, and FIG. 79 and Table C-1 show the standard deviation (SD value) . Show.
In FIG. 78 , the vertical axis represents luminance, and the horizontal axis represents the position in the direction parallel to the light incident surface on the light exit surface. In FIG. 79 , the chain line indicates an SD value (0.2) acceptable for use in an image display device, and the alternate long and short dash line indicates an SD value (0.1) sufficient for use in an image display device. ing.

[Table C-1]

In the surface light source device of Production Example C-1, the luminance is not constant, and a hot spot (maximum part) appears, and even in the surface light source devices of Production Examples C-2 and 3, this luminance unevenness cannot be resolved. . That is, in Production Example C-2 in which the light scattering degree of the area facing the light source on the opposite surface is lower than the light scattering degree of the area facing the portion between the light sources Although it was possible to suppress the luminance of the portion facing the LEDs, it was not possible to increase the luminance of the portion facing the LEDs. On the other hand, in Production Example C-3 in which the groove structure was formed on the light incident surface of the light guide plate, the luminance of the portion directly facing between the LEDs could be suppressed to some extent, and the luminance of the portion corresponding to between the LEDs could be increased. It wasn't.
On the other hand, in the surface light source device of Production Example C-11, the luminance was almost constant regardless of the location, and no hot spot appeared.
Further, in order to achieve a narrow-frame display device that is currently in trend, it is necessary to set G (horizontal distance between the light incident surface and the display area) to about 7 mm. In the surface light source device (P = 27.5 mm), the SD value of the luminance 7 mm inside from the light incident surface side end of the light exit surface was as extremely low as 0.04. Therefore, the light incident surface of the light guide plate has a plurality of concave portions or convex portions, and the opening portion or the bottom surface thereof has a plurality of concave portions or convex portions having a long anisotropic shape in a direction perpendicular to the light emitting surface. The light scattering degree of the area facing the light source is lower than the light scattering degree of the area facing the portion between the light sources on the light exiting surface and / or the opposing surface of the light guide plate. In the surface light source device configured to have the light scattering processing, even if the LED array pitch is expanded to about 30 mm under the condition of G = 7 mm, that is, P / G> 4, at least the image It is believed that an SD value (0.2) acceptable for use in a display device is obtained.

[Reference Experiment C1]
The optimum values of light scattering processing and frame overlap were investigated.
Take out the surface light source device part (the one with the opening starting from the position corresponding to 8 mm inside from the light incident surface end of the light guide plate) from the commercially available LED TV (BRAVIA EX710 manufactured by Sony Corporation), The light incident surface is a mirror surface, and the opposite surface is 2 mm, 6 mm, or 10 mm from the end of the light incident surface. What was applied uniformly (with uniform dot density) in a staggered arrangement with a pitch of 2.55 mm × 1.5 mm (ie, the overlap between the frame and the light scattering process was 6 mm, 2 mm or − 2 mm (without overlap)) or a groove structure on the light incident surface in the same manner as in Production Example C-11, and 2 mm, 6 mm, or 10 m from the light incident surface side end on the opposite surface The in-plane average luminance of the light emitting area was measured in place of the light scattering process from m.
FIG. 80 shows values obtained by dividing the in-plane average luminance of the light-emitting areas of these surface light source devices by the input power (values obtained by correcting variations in luminance efficiency and input power).
From FIG. 80 , the in-plane average brightness is reduced if there is no overlap between the light scattering process and the frame, but on the other hand, the in-plane average brightness is reduced even if the overlap is too large, so the overlap is about 2 mm. It was confirmed that it was preferable.

[Reference Experiment C2]
A ray tracing simulation model 1 of the same surface light source device as in Production Example C-11, and a simulation model 2 and a simulation model 3 in which the LED array pitch P was changed to 22.5 mm and 25 mm were prepared.
Using these simulation models 1 to 3, using Light Tools (Optical Research Associates) version 7.1, the luminance distribution at the inner side (G = 7 mm) 7 mm from the light incident side edge of the light exit surface of the light guide plate The light in the region directly facing the dot density ρ1 of the light scattering processing pattern in the region facing the light source near the light incident surface and the portion between the light source near the light incident surface and the light source, where the SD value is less than 0.2. When the combination of the dot density ρ2 of the scattering pattern was calculated, the following results were obtained.
When the results are plotted with ρ2 / ρ1 as the vertical axis and P / G as the horizontal axis, linearity (ρ2 / ρ1 = 1.4 × (P / G) −3.0) as shown in FIG. 81 is recognized. It was. Thereby, if ρ1 and ρ2 are adjusted so that ρ2 / ρ1 satisfies the following relational expression, it is possible to realize an outgoing light distribution without luminance unevenness at a desired P / G.
2.9 ≦ 1.4 × (P / G) −ρ2 / ρ1 ≦ 3.1

[Table C-2]

[Standard Reference C]
The arrangement pitch P of LEDs is 10.5 mm, and the horizontal distance G between the light incident surface of the light guide plate (material: polymethyl methacrylate, thickness: 4 mm) and the display area is 16.5 mm (P / G = 0.64). From the commercially available LED TV (BRAVIA KDL-32EX700 manufactured by Sony Corporation), only the surface light source device part is taken out, and the LEDs are rearranged so that the LED arrangement pitch is about 42 mm (P / G = 2.55) The luminance at the position 16.5 mm inside (corresponding to the display area start portion) from the light incident surface side edge of the light exit surface of the light guide plate and further 10 mm inside (26.5 mm inside from the light incident surface side edge) is obtained. Measurement was performed using a two-dimensional color luminance meter (CA-2000) manufactured by Konica Minolta.

[Production Example C-21]
In the above surface light source device, a polyethylene terephthalate film having an average thickness of 125 μm and having the groove structure of the present invention formed on the light incident surface of the light guide plate is pasted using a transparent double-sided adhesive sheet (CS9621T manufactured by Nitto Denko Corporation). The luminance at a position 26.5 mm inside from the light incident surface side end of the light exit surface was measured. The groove structure has the surface profile shown in FIG. 2 manufactured by speckle pattern exposure, and the average pitch is about 6 μm and the average depth is about 4 μm.

[Production Examples C-31 to 33]
In the surface light source device, the light guide plate was replaced with the following, and the luminance at a position 26.5 mm inside from the light incident surface side end of the light exit surface was measured. As with the light guide plate of Production Example C-21, each of the light guide plates is made of a polyethylene terephthalate film having a predetermined microstructure and an average thickness of 125 μm on the light incident surface of the standard reference light guide plate. It was manufactured by sticking using
Manufacture example C-31: Light guide plate having a prism with a 90 ° apex angle (pitch: about 50 μm) on the light entrance surface Production example C-32: Light guide plate having a lenticular lens (pitch: about 120 μm) on the light entrance surface C-33: Light guide plate having prisms with apex angle R (pitch: about 50 μm) on the light incident surface

FIG. 84 shows the luminance variation of the surface light source device using the light guide plate of the manufacturing example and the standard reference C. In FIG. 84 , the vertical axis represents the luminance at a position 26.5 mm inside the light incident surface side end of the light exit surface, and the horizontal axis represents the position in the width direction of the light incident surface of the light guide plate.
In the surface light source device of Production Example C-21, the luminance was almost constant regardless of the location, and no hot spot appeared. On the other hand, in the case of using a light guide plate (standard reference C) used in a commercial television or a light guide plate corresponding to the light guide plate disclosed in the prior art documents (Production Examples C-31 to 33). The brightness was not constant, a hot spot (maximum part) appeared, and the brightness unevenness could not be solved.

<Production Example D>

In the following Production Examples D-1 to 17, 42, and 43, the light incident surface of the light guide plate has an ultraviolet curable resin layer in which a vertically long or isotropic depression having the surface shape of FIGS. 23 to 32 is formed. The base material which consists of a polyethylene terephthalate film was manufactured by affixing using a transparent double-sided adhesive sheet (PD-S1 by a Panac company).
Table D-1 below shows the diffusion angle, the average pitch of the recesses, the average depth of the recesses, and the substrate thickness of the films of FIGS .

[Table D-1]

[Reference 1]
The arrangement pitch P of LEDs is 10.5 mm, and the horizontal distance G between the light incident surface of the light guide plate (material: polymethyl methacrylate, thickness: 4 mm) and the display area is 16.5 mm (P / G = 0.64). From the commercially available LED television (BRAVIA KDL-32EX700 manufactured by Sony Corporation), only the surface light source device part was taken out, and the LEDs were rearranged so that the LED array pitch P was about 21 mm.
A diffusion sheet (installed in BRAVIA KDL-32EX700 manufactured by Sony Corporation) is disposed on the light exit surface side of the light guide plate, and at a position 1 m from the normal direction of the light exit surface, a two-dimensional color luminance meter manufactured by Konica Minolta ( CA-2000) was installed and the luminance of the light exit surface was measured.

[Evaluation of luminance unevenness suppression ability]
From the light emission surface luminance data measured by the two-dimensional color luminance meter (CA-2000), the distance G from the light incident surface side end of the light emission surface is 20 mm, 25 mm, 30 mm, 35 mm and 40 mm (light incident Luminance profiles were extracted in a direction parallel to the light incident surface (in the direction (A) in FIG. 9) 20 mm, 25 mm, 30 mm, 35 mm, and 40 mm inside from the surface side end.
In order to cancel the luminance gradient unrelated to the hot spot from each of the luminance profiles L (X) (X axis: distance in the direction parallel to the light incident surface, Y axis: luminance L), the LED pitch P (in this case) Is a value smoothed by taking an average value in a range corresponding to about 21 mm) (moving average value)

And a standard deviation value (SD value) obtained by dividing the luminance profile by the moving average value of the luminance profile was obtained and used as an index of luminance unevenness, that is, hot spot by the LED.
86 to 91 are graphs in which P / G (P = 21 mm, G = 20, 25, 30, 35, 40 mm) is taken on the X axis, and the above standard deviation value (indicator of luminance unevenness) is taken on the Y axis. .

[Evaluation of achievement]
In order to cancel the uneven brightness of the hot spot, the brightness profile in the light propagation direction (direction (B) in FIG. 9) from the brightness data of the light exit surface measured by the two-dimensional color luminance meter (CA-2000). The average value T (X ′) of L (X) in the range of ± 1.5 P (P is the LED pitch) from the central LED in the evaluation range in the direction parallel to the light incident surface (A direction in FIG. 9). ) Was calculated and plotted with the distance in the direction perpendicular to the light incident surface (direction B in FIG. 9) as the X ′ axis and the Y axis as T (X ′) (FIG. 16). In this luminance profile, a shielding plate for fixing the light guide plate is installed in the range (X = 0 to 16.5 mm) from the light incident surface of the light guide plate to the inside of 16.5 mm. Is zero. Next, X = 16.5 mm to 390 mm of this luminance profile was extracted.

[Production Example D-1]
In the surface light source device of Reference 1, a polyethylene terephthalate film having an average thickness of 250 μm and having a groove structure to be described later formed on the light incident surface of the light guide plate is pasted using a transparent double-sided adhesive sheet (PD-S1 manufactured by Panac Corporation). Except for the above, a luminance profile in the direction parallel to the light incident surface of the light exit surface was measured in the same manner as in Reference 1, and the luminance unevenness was obtained.
The groove structure has the surface profile shown in FIG. 23 manufactured by speckle pattern exposure. The average pitch is about 7.3 μm and the average depth is about 2.5 μm. Moreover, the diffusion angle (FWHM) when measured using GC-5000L in the state of the film alone was 47 ° × 4 °.
Similarly to the reference 1, X = 16.5 to 390 mm are extracted from the luminance profile in the light propagation direction, and the ratio of the luminance value to the reference 1 for each measurement point included in this range (each measurement The value obtained by dividing the luminance value of the point by the luminance value at the same location (X) of the reference 1) was determined, and the minimum value (MIN) and the maximum value (MAX) were listed in Table D-2.

[Production Example D-2]
In the surface light source device of Reference 1, a polyethylene terephthalate film having an average thickness of 100 μm and having a groove structure described later formed on the light incident surface of the light guide plate is pasted using a transparent double-sided adhesive sheet (PD-S1 manufactured by Panac Corporation). Except for the above, a luminance profile in the direction parallel to the light incident surface of the light exit surface was measured in the same manner as in Reference 1, and the luminance unevenness was obtained.
Further, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured in the same manner as in Reference 1, and the values of MIN and MAX were obtained in the same manner as in Production Example D-1.
The groove structure has the surface profile shown in FIG. 24 manufactured by speckle pattern exposure, and the average pitch is about 5.4 μm and the average depth is about 3.6 μm. Moreover, FWHM when measured using GC-5000L in the state of the film alone was 63 ° x 1 °.

[Reference 2]
Except for setting the LED arrangement pitch P to about 31.5 mm, the luminance unevenness suppressing ability and the reach were evaluated in the same manner as in Reference 1.
[Production Example D-3]
Reference 2 except that a polyethylene terephthalate film having an average thickness of 250 μm and having the same groove structure as in Production Example D-1 formed on the light incident surface of the light guide plate was attached using the same transparent double-sided adhesive sheet as in Production Example D-1. In the same manner as described above, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured to determine the luminance unevenness.
Similarly to Reference 2, the luminance profile in the light propagation direction (the direction perpendicular to the light incident surface) is measured, and MIN and MAX are the same as in Production Example D-1, except that the reference is set to Reference 2. The value was determined.
[Production Example D-4]
Reference 2 except that a polyethylene terephthalate film having an average thickness of 100 μm and having the same groove structure as in Production Example D-2 formed on the light incident surface of the light guide plate was attached using the same transparent double-sided adhesive sheet as in Production Example D-2.
In the same manner as described above, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured to determine the luminance unevenness.
Similarly to Reference 2, the luminance profile in the light propagation direction (the direction perpendicular to the light incident surface) is measured, and MIN and MAX are the same as in Production Example D-1, except that the reference is set to Reference 2. The value was determined.

[Reference 3]
Except for setting the LED arrangement pitch P to about 42 mm, the luminance unevenness suppressing ability and the reach were evaluated in the same manner as in Reference 1.
[Production Example D-5]
Reference 3 except that a polyethylene terephthalate film having an average thickness of 250 μm and having the same groove structure as in Production Example D-1 formed on the light incident surface of the light guide plate was attached using the same transparent double-sided adhesive sheet as in Production Example D-1. In the same manner as described above, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured to determine the luminance unevenness.
Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.
[Production Example D-6]
Reference 3 except that a polyethylene terephthalate film having an average thickness of 100 μm and having the same groove structure as in Production Example D-2 formed on the light incident surface of the light guide plate was attached using the same transparent double-sided adhesive sheet as in Production Example D-2. In the same manner as described above, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured to determine the luminance unevenness.
Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.

86 to 91 are graphs in which the luminance unevenness (SD values) of Production Examples D-1 to 6 are taken on the Y axis and P / G is taken on the X axis.
Table 2 summarizes the evaluation results of the degree of achievement (MIN, MAX).

86, 87, and 88 compare the performance differences of the respective light guide plates by aligning conditions (LED pitch P of the surface light source device) other than the shape of the light incident surface. From any of the figures, it can be confirmed that the manufacturing examples D-1 to 6 have smaller luminance unevenness than the reference. Furthermore, when P / G is small as shown in FIGS. 86 and 87 , there is a difference between the reference and the manufacturing example, but there is almost no difference between the manufacturing examples. (Furthermore, when P / G is 1 or less, the luminance unevenness is originally small, so the difference between the manufacturing example and the reference is small.) On the other hand, when the P / G region is high as shown in FIG . Production Example D-6 (surface shape in FIG. 24 (longitudinal diffusion angle is 63 °)) performs better than Example D-5 (surface shape in FIG. 23 (longitudinal diffusion angle is 47 °)) I understand that is good.
FIGS. 89, 90, and 91 compare the cases where the LED pitch P is changed using the same light guide plate. From these figures, in the light guide plate of Production Example D as well as the reference, the same performance (luminance unevenness reduction performance) is obtained as long as P / G is the same value even if the LED arrangement pitch P is changed. Can be confirmed.

[Table D-2]

  Looking at the degree of achievement (MAX, MIN), the films of Production Examples D-1, 3, 5 are generally better.

In the subsequent production examples, the same LED arrangement as that of the reference 3 was adopted, and the luminance unevenness and the reach were evaluated in the same manner as in the reference 3 [Production Examples D-7 to 11].
A film was prepared in which longitudinal grooves having an angle of −10 °, −5 °, 0 °, 5 ° or 10 ° with respect to the thickness direction of the light guide plate were formed on a polyethylene terephthalate film having an average thickness of 125 μm. In the same manner as in Reference 3, except that the above film was attached to the light incident surface of the light guide plate using a transparent double-sided adhesive sheet (PD-S1 manufactured by Panac Co., Ltd.). A luminance profile was measured to determine luminance unevenness.
Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.
The groove structure has the surface profile of FIG. 25 manufactured by speckle pattern exposure, and the average pitch is about 6.6 μm and the average depth is about 3.4 μm. Moreover, FWHM when measured using GC-5000L in the state of the film alone was 83 ° x 3 °.
The suppression ability of Production Examples D-7 to 11 is shown in FIG. 92 , and the reach (MIN, MAX) is shown in Table D-3.

[Table D-3]

Even when the direction of the longitudinal groove was changed in the range of −10 ° to 10 °, the luminance unevenness suppressing ability ( FIG. 92 ) and the degree of achievement (Table D-3) did not change significantly.

[Production Examples D-12 to 15, 12 ′ to 15 ′]
Reference 3 except that the same film as the film having the groove structure of Production Example D-1 was cut to a width of 4 mm and pasted with a gap (seam) of 0 to 1.5 mm on the light incident surface. In the same manner as described above, the luminance profile in the direction parallel to the light incident surface of the light emitting surface was measured to obtain luminance unevenness.
Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.
At that time, the gap (seam) between the films does not cover the LED light emitting surface (and the facing portion) (Production Examples D-12 to 15) and the LED light emitting surface of the LED (Manufacturing) Two types of examples D-12 ′ to 15 ′) were prepared.
The luminance unevenness suppressing ability of Production Examples D-12 to 15 and Production Examples D-12 ′ to 15 ′ is shown in FIGS. 93 and 94 , and the reach (MIN, MAX) is shown in Table D-4. In addition, the thing (equivalent to manufacture example D-6) which affixed the film in which the groove | channel structure was formed without cutting (without opening a clearance gap) was made into the reference 4.

[Table D-4]

There was no significant difference in the degree of achievement (Table D-4) depending on the presence / absence and position of a gap (seam). On the other hand, with regard to luminance unevenness, when there is a gap (seam) on the LED light emitting surface, the luminance unevenness has increased remarkably ( FIG. 93 ), but a gap (seam) is provided between the LED light emitting surfaces . There was no problem in performance ( FIG. 94 ).

[Production Examples D-16, 17]
On the light incident surface of the light guide plate, a polyethylene terephthalate film having a diffusion angle (FWHM) of 83 ° × 3 ° (surface shape diagram 25 ) and an average thickness of 125 μm, and a diffusion angle (FWHM) of 92 ° × 50 ° ( Surface shape FIG. 26 ), a polyethylene terephthalate film having an average thickness of 250 μm, respectively, is applied in the same manner as in Reference 3 except that the same transparent double-sided adhesive sheet as in Production Example D-1 is applied. The luminance profile in the direction parallel to the surface was measured to determine the luminance unevenness.
Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.
[Production Examples D-35, 36]
Luminance unevenness, MIN, and MAX were measured in the same manner as in Production Example D-16 or 17 except that the surface shape was rotated by 90 ° (that is, the indentation was horizontally long).
The results are shown in FIG. 95 and Table D-5.

[Table C2-5]

In the case where the shape of the indentation was horizontally long, the luminance unevenness suppressing ability was lowered ( FIG. 95 ), and the reach (Table D-5) was also deteriorated.

[Production Example D-37 to 40]
Except that the light guide plate was replaced with the following, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured in the same manner as in Reference 3, and the luminance unevenness was obtained. Similarly to Reference 3, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured, and MIN and MAX were the same as in Production Example D-1, except that the reference was set to Reference 3. The value was determined.
Each light guide plate is made of a polyethylene terephthalate film having an average thickness of 250 μm (Production Example D-38 only 400 μm) having a predetermined fine structure, as in the light guide plates of Production Examples D-1 to 6. It manufactured by sticking to the light-incidence surface of the light-guide plate using a transparent double-sided adhesive sheet (PD-S1 by Panac Co., Ltd.).
Production Example D-37: A hemisphere having a radius of 30 μm is randomly arranged on the light incident surface with an average pitch of 70.6 μm.
Production Example D-38: A prism with a 90 ° apex angle arranged on the light incident surface periodically (grating) with a pitch of about 60 μm.
Production Example D-39: A prism with apex angle R arranged on the light incident surface periodically (grating) with a pitch of about 50 μm.
Production Example D-40: A lens in which lenticular lenses are periodically arranged at a pitch of about 150 μm on the light incident surface.
The results are shown in FIG. 96 and Table D-6. In FIG. 96 and Table D-6, for comparison, a groove structure of Production Example D-6 (surface profile: FIG. 24 , average pitch: about 5.4 μm, average depth: about 3.6 μm was formed. The data of a production example in which a polyethylene terephthalate film is attached to the light incident surface are also shown.

[Table D-6]

  Production Example D-37 had poor reach, and Production Examples D-38, 39, and 40 had low suppression ability.

[Production Examples D-19 to 23] [Production Examples D-42 and 43]
Except that the light guide plate was replaced with one having the following surface shape, the luminance profile in the direction parallel to the light incident surface of the light exit surface was measured in the same manner as in Reference 3 to obtain luminance unevenness.
Production Example D-19: 27
Production Example D-20: FIG. 23 (corresponding to Production Example D-5)
Production Example D-21: FIG. 29
Production Example D-22: 28
Production Example D-23: 30
Production Example D-42: FIG. 31 (isotropic depressions that are not vertically long are formed)
Production Example D-43: FIG. 32 (isotropic depressions that are not vertically long are formed)
With respect to the luminance unevenness measured above, 0.020 or less was evaluated as ○, 0.020 or more and less than 0.050 as Δ, 0.050 or more as ×, and vertical FWHM (in the thickness direction of the light guide plate ( FWHM (in the plane perpendicular to the light exit surface), calculated from the transmitted light intensity cross section in the same direction as the longitudinal direction of the longitudinal groove), horizontal axis FWHM (in the plane parallel to the light exit surface) in the width direction of the light guide plate FWHM) was plotted as the vertical axis. The results are shown in FIG .
Regarding the luminance unevenness suppressing ability ( FIG. 97 ), it can be said that the lateral FWHM is preferably 60 ° or more.

  For the light guide plates of Production Examples D-19 to 22, 42 and 43, the luminance profile in the light propagation direction (direction perpendicular to the light incident surface) was measured in the same manner as in Reference 3, and the reference was set as Reference 3. Except for the above, the values of MIN and MAX were determined in the same manner as in Production Example D-1, and the results are shown in Table D-7.

[Table C2-7]

  Taking the reach (Table D-7) into consideration, it can be said that Production Example D-17 is not an optimal shape.

<Production Example E>

[Production Example E-1A]
PMMA light guide plate (flat plate of width 400mm, length 700mm, thickness 4mm) used in Sony liquid crystal television BRAVIA 32EX700 as a base material, acrylic adhesive (laminated on release paper as adhesive layer) G ′ = 77,000 Pa (G ₀ ′ = 18,000)
00Pa)) film (PD-S1 manufactured by Panac Co., Ltd., pressure-sensitive adhesive film thickness: 25 μm, TG / DTA (weight reduction rate) at 100 ° C.−0.06%), and as a light diffusion layer, from polyethylene terephthalate A multilayer film in which a layer made of an ultraviolet curable resin having a groove structure with a diffusion angle of 60 ° × 1 ° on the surface was prepared on a transparent base film (A4300 manufactured by Toyobo Co., Ltd.) having a thickness of 125 μm.
Next, prepare two sheets each of the adhesive layer and the light diffusion layer cut to the size of the side surface in the longitudinal direction of the base material (the light diffusion layer is cut so that the direction of the diffusion angle is 60 degrees in the longitudinal direction) The adhesive layer and the light diffusing layer were adhered to both side surfaces in the longitudinal direction of the base material in this order using a roller to form a light incident part (light incident surface), and a light guide plate was produced.
Specifically, first, the pressure-sensitive adhesive film is temporarily fixed to the side surface of the base material so that the pressure-sensitive adhesive and the base material are in contact with each other. Squeezing and removing air bubbles. After that, the release film of the adhesive film is peeled off, and the light diffusion layer is temporarily fixed thereon so that the surface opposite to the surface having the concavo-convex structure is in contact with the adhesive, and from one end of the substrate side surface. The other end of the concavo-convex structure was squeezed with a roller and pasted.
One diffusion sheet (TDF187 manufactured by Toray Sehan Co., Ltd.) is laminated on one main surface of the light guide plate produced as described above, and 18 pieces (9 on each light incident surface) along the light incident surface. ) Were arranged substantially evenly so that the arrangement pitch was 42 mm (distance between the LED and the light incident surface: 0.8 mm), and a surface light source device was produced.
Using a two-dimensional color luminance meter (CA-2000) manufactured by Konica Minolta, the brightness at a position corresponding to the inner side 10 mm from the light incident surface side end on the diffusion sheet laminated on the light guide plate is turned on. It was measured along the longitudinal direction of the light guide plate. FIG. 102 shows the obtained luminance profile.

[Production Example E-1B]
A surface light source device was prepared in the same manner as in Production Example E-1A, except that the light diffusion layer was not used as an adhesive layer, and only both ends were fixed with a 4 mm square adhesive tape and laminated on both side surfaces in the longitudinal direction of the base material. A luminance profile 10 mm inside from the end of the light incident surface was measured. The obtained luminance profile is shown in FIG .

  In the surface light source device of Production Example E-1A in which the light diffusion layer was fixed to the base material via the adhesive layer, the luminance was substantially constant along the longitudinal direction of the light guide plate, but the production without using the adhesive layer In the surface light source device of Example E-1B, the luminance unevenness in the longitudinal direction of the light guide plate was severe.

[Production Example E-2A]
A base plate made of PMMA LX N865 manufactured by Mitsubishi Rayon Co., Ltd., having a width of 30 mm, a length of 250 mm and a thickness of 4 mm, and an acrylic pressure-sensitive adhesive (G ′ = 77,000 Pa) laminated on a release paper as an adhesive layer (G ₀ ′ = 18,000 Pa)) film (PD-S1, manufactured by Panac Corporation, pressure-sensitive adhesive film thickness: 25 μm, peel strength: 0.75 N / mm), and a light diffusion layer having a thickness of 125 μm On the base film polyethylene terephthalate (A4300 manufactured by Toyobo Co., Ltd.) layer, a multilayer film having a layer made of an ultraviolet curable resin having a fine concavo-convex structure on its surface was prepared.
Next, the adhesive layer and the light diffusing layer are cut to the size of the side surface in the longitudinal direction of the base material, and the light is incident on one side of the base material in the longitudinal direction by adhering the adhesive layer and the light diffusing layer in this order using a roller. The light guide member was produced. Specifically, first, the pressure-sensitive adhesive film is temporarily fixed to the side surface of the base material so that the pressure-sensitive adhesive and the base material are in contact with each other. Squeezing and removing air bubbles. After that, the release film of the adhesive film is peeled off, and the light diffusion layer is temporarily fixed thereon so that the surface opposite to the surface having the concavo-convex structure is in contact with the adhesive, and from one end of the substrate side surface. The other end of the concavo-convex structure was squeezed with a roller and pasted.

[Production Example E-2B]
A light guide plate was produced in the same manner as in Production Example E-2A except that the thickness of the transparent base film layer of the light diffusion layer was changed to 250 μm.
[Production Example E-2C]
A light guide plate was produced in the same manner as in Production Example E-2A except that the thickness of the substrate was changed to 3.5 mm.
[Production Example E-2D]
A light guide plate was produced in the same manner as in Production Example E-2C except that the thickness of the transparent base film layer of the light diffusion layer was changed to 250 μm.
[Production Example E-2E]
Acrylic pressure-sensitive adhesive (G ′ = 84,000 Pa (G ₀ ′ = 19,800 Pa)) film (TR-1801A manufactured by Fujimori Kogyo Co., Ltd., pressure-sensitive adhesive film thickness) laminated on release paper. A light guide plate was produced in the same manner as in Production Example E-2A, except that TG / DTA (weight reduction rate) -0.05% at 25 [mu] m, 100 [deg.] C.-0.05%, peel strength: 0.63 N / mm).
[Production Example E-2F]
Acrylic pressure-sensitive adhesive (G ′ = 68,000 Pa (G ₀ ′ = 16,900 Pa)) film (CCL / D1 / T3T3 manufactured by New Tack Kasei Co., Ltd., pressure-sensitive adhesive film) A light guide plate was produced in the same manner as in Production Example E-2A except that the thickness was changed to 25 μm and the peel strength was 0.61 N / mm.
[Production Example E-2G]
Acrylic pressure-sensitive adhesive (G ′ = 44,000 Pa (G ′ ₀ = 10,700 Pa)) film (EXC10-076 manufactured by Toyo Ink Co., Ltd., pressure-sensitive adhesive film thickness) laminated on the release paper. A light guide plate was produced in the same manner as in Production Example E-2A except that the thickness was changed to 50 μm).
[Production Example E-2H]
A film (MO-3006C manufactured by Lintec Corporation) made of an acrylic pressure-sensitive adhesive (G ′ = 160,000 Pa (G ₀ ′ = 44,600 Pa)) laminated on release paper.
A light guide plate was produced in the same manner as in Production Example E-2A except that the pressure-sensitive adhesive film thickness was changed to 25 μm, TG / DTA (weight reduction rate) at 100 ° C.—0.09%.
[Production Example E-2I]
A film (MO-3012C manufactured by Lintec Corporation, pressure-sensitive adhesive film thickness) made of an acrylic pressure-sensitive adhesive (G ′ = 30,000 Pa (G ₀ ′ = 6,100 Pa)) laminated on a release paper. A light guide plate was produced in the same manner as in Production Example E-2A, except that TG / DTA (weight reduction rate) at 0.10 / 25 μm and 100 ° C. (0.10%) was changed.

In the light guide plates of Production Examples E-2A to 2I, the light diffusion layer was firmly fixed to the base material. After these light guide plates were allowed to stand under the following conditions a to d, the occurrence of peeling between the base material and the adhesive layer and between the adhesive layer and the light diffusion layer was visually observed and evaluated based on the following criteria.
(conditions)
a. 250 hours at 90 ° C. and 30% RH b. 12 hours at 100 ° C. dry c. 1000 hours under dry conditions at 100 ° C. d. 24 hours under 85 ° C dry conditions (evaluation criteria)
A: No peeling at all O: Peeling is less than 1% of the bonding area Δ: Peeling is from 1% to less than 30% of the bonding area ×: Peeling is at least 30% of the bonding area

  The results are shown in Table E1-1. In the light guide plates of Production Examples E-2A to 2H, in which the adhesive layer is composed of an adhesive with G ′ = 40,000 to 180,000 Pa, the light diffusion layer can be peeled off even when placed under high temperature (humidity) for a long time. It didn't happen much.

[Table E1-1]

[Production Example E-3A]
As a base material, a PMMA LX N865 manufactured by Mitsubishi Rayon Co., Ltd., a flat plate with a width of 30 mm, a length of 250 mm, and a thickness of 3.5 mm, an acrylic pressure-sensitive adhesive (G ′ = 77) laminated on a release paper as an adhesive layer , 000 Pa (G ₀ ′ = 18,000 Pa)) film (PD-S1 manufactured by Panac Corporation, pressure-sensitive adhesive film thickness: 25 μm), and a transparent base film having a thickness of 125 μm made of polyethylene terephthalate as a light diffusion layer (Toyobo) A multilayer film provided with a layer made of an ultraviolet curable resin having a groove structure with a diffusion angle of 60 ° × 1 ° on the surface was prepared on an A4300) layer.
Next, a laminator is used to laminate an adhesive layer on the surface of the light diffusion layer opposite to the surface having the concavo-convex structure to form a laminate, and this laminate is cut into the size of the side surface in the longitudinal direction of the substrate. The release paper of the adhesive layer was peeled off, and a light incident part was formed on one of the side surfaces in the longitudinal direction of the base material by using a roller so as to be in the order of the adhesive layer and the light diffusion layer, and a light guide plate was produced. .
One diffusion sheet (TDF187 manufactured by Toray Sehan Co., Ltd.) is laminated on one main surface of the light guide plate produced as described above, and 18 pieces (9 on each light incident surface) along the light incident surface. ) LEDs were arranged substantially evenly so that the arrangement pitch was 26 mm (distance between LED and light incident surface: 0.8 mm), and a surface light source device was produced.
Next, the LED is turned on, and using a Konica Minolta two-dimensional color luminance meter (CA-2000), the distance from the light incident surface side end on the diffusion sheet laminated on the light guide plate is X mm ( The operation of obtaining the luminance profile by measuring the luminance at the Xmm inner side from the light incident surface side end portion along the longitudinal direction of the light guide plate was repeated in increments of 1 mm for a range of X = 10 to 20 mm. Based on the brightness profile obtained in this way, the distance (X) from the light incident surface side end that can be judged to have eliminated the brightness unevenness was found to be 13 mm. [Production Example E-3B]
Similar to Production Example E-3A, except that the jig used for laminating the laminate of the adhesive layer and the light diffusion layer is changed to a spatula made of polypropylene resin. It was 14 mm when the distance (X) from was measured.
[Production Example E-3C]
Production Example E-, except that a polyethylene terephthalate film having a thickness of 250 μm was inserted between the spatula and the laminate when laminating the laminate of the adhesive layer and the light diffusion layer with a spatula (squeezed with a spatula through the film). In the same manner as in 3B, the distance (X) from the end portion on the light incident surface side where there was no luminance unevenness was measured and found to be 13 mm.

<Production Example F>

[Production Example F-11]
A polyethylene terephthalate film having an average thickness of 125 μm and having a groove structure having the surface profile (average pitch: about 6 μm, average depth: about 4 μm) shown in FIG. The light-scattering processing shown in FIG. 107 was applied to the opposite surface (circular diffusive dots made of diffusing beads and a binder having a diameter of 0.8 mm to 1.3 mm in a staggered arrangement (in a triangular lattice pattern). ) Ρ1 = 0% and ρ2 = 60% from 1 to 4 mm (light shielding portion) from the light incident surface side end portion, and ρ1 = from 4 to 6 mm (light shielding portion (boundary area)) from the light incident surface side edge portion. 7%, ρ2 = 20%, light guide plate (provided to be ρ1 = ρ2 = 8% after 6 mm from the light incident surface side end portion (non-light-shielding portion)) (material: polymethyl methacrylate, thickness: 3.0mm, : 409 mm, length: 721 mm), LED (light emitting surface size 5.0 mm (width direction) × 3.0 mm (thickness direction), 36 LEDs)) The arrangement pitch P is 19.2 mm along the light incident surface. It arranged so that it might become. On top of this, a diffusion sheet, a prism sheet, and a reflective polarizing sheet (DBEF manufactured by 3M) are laminated in this order, and on top of that, an opening having a size that sufficiently covers the light guide plate and the LED is 395 mm × 700 mm. The surface light source device was produced by arranging the frame having the light guide plate so as to face the light exit surface side.
Using a secondary color luminance meter (CA2000A manufactured by Konica Minolta), the luminance is measured from the front direction (V = 0 °, H = 0 °) of the light emitting surface, and the standard deviation (SD value) of the luminance of the light emitting surface is calculated. Asked.
The results are shown in FIG . The luminance S.D. D. The value was as very low as 0.02 or less in P / G = 1 to 2.6 (G is a distance (mm) from the light incident surface).

Further, when the light emitting surface is viewed from an oblique direction (V (Vertical) = 45 ° or H (Horizontal) = 20 °) (the measurement direction of the luminance meter is V = 45 ° or H = 20 with respect to the front surface of the light emitting surface). (Measured at an angle of inclination), the luminance S.D. D. Values are shown in Table F-2. Here, H and V indicate the inclination angles of the luminance meter, and the inclination angles in directions parallel to the light incident surface (inclination angles rotated around an axis perpendicular to the light incident surface), the light incident surface, respectively. Is a direction in which a positive value falls at the center of the light emitting area or the display area at an inclination angle in a direction perpendicular to (an inclination angle rotated about an axis parallel to the light incident surface).
In the surface light source device of Production Example F-11, not only from the front but also from the front, the luminance unevenness when viewing the light exit surface from an oblique direction was reduced.

[Table F-2]

[Production Example F-12]
The light scattering processing of the opposing surface of the light guide plate is as shown in FIG. 109 (circular diffusive dots having a diameter of 0.8 mm to 1.3 mm made of diffusing beads and a binder are arranged in a staggered manner (in a triangular lattice pattern), Ρ1 = 0% and ρ2 = 60% from the light incident surface side edge portion to 1.5 to 4.5 mm (light shielding portion), 4.5 to 6 mm from the light incident surface side edge portion (light shielding portion (boundary area)) Ρ1 = 10%, ρ2 = 13%, and after 6 mm from the light incident side end (non-light-shielding portion), ρ1 = 8% and ρ2 = 9%. 11 in the same manner as in Production Example F-11 except that the difference in light scattering between the region facing the light source and the region facing the light source in the boundary area is small. Of the luminance distribution of D. The value was determined.
The luminance unevenness is observed in Production Example F-11 when observed from either the front (V = H = 0 °) or the oblique direction (V = 0 °, H = 20 °, V = 45 °, H = 0 °). It was smaller than that.

[Production Example F-13]
In the surface light source device of Production Example F-12, the frame is removed and the display panel has the same configuration as that shown in FIG . 4 mm × 696.4 mm) was arranged so as to face the light exit surface side of the light guide plate, a display device was created, and luminance unevenness in the display area was observed.
The luminance unevenness in the display area is a manufacturing example even when observed from either the front (V = H = 0 °) or the oblique direction (V = 0 °, H = 20 °, V = 45 °, H = 0 °). It was smaller than that of F-11.

<Production example G>

First, the evaluation method of Production Example G will be described.
1. Evaluation system (hot spot evaluation)
The following evaluation system 1 is used for Production Examples G-1 to 12 and 21 to 30, and the following evaluation system 2 is used for Production Examples G-13 to 15 and Production Examples G-31 and 32. Evaluation was performed.
Evaluation system 1
Five LEDs are arranged approximately evenly along the light incident surface of the light guide plate so that the light emitting surface of the LED is parallel to the light incident surface and the arrangement pitch is 18.8 mm (LED and light incident surface). The surface light source device was fabricated by laminating an optical sheet (described later) on the light exit surface side of the light guide plate. The external shape of the LED is 5.6 mm wide × 3.0 mm high.
Evaluation system 2
Five LEDs are arranged approximately evenly along the light incident surface of the light guide plate so that the light emitting surface of the LED is parallel to the light incident surface and the arrangement pitch is 9.4 mm (LED and light incident surface). The surface light source device was fabricated by laminating an optical sheet (described later) on the light exit surface side of the light guide plate. The external shape of the LED is 5.6 mm wide × 3.0 mm high.
Specifically, the LED is turned on, from the normal line direction of the light output surface of the optical sheet laminated on the light guide plate at a position 0.5 m from the light output surface (hot spot evaluation when viewed from the front) and from the normal direction. A Konica Minolta two-dimensional color luminance meter (CA-2000) is installed at a position 0.5 m from the light exit surface in the direction of 30 degrees obliquely ( FIG. 125 ) (hot spot evaluation when viewed from the oblique direction) . The luminance distribution was measured. From the luminance data of the light exit surface measured by a two-dimensional color luminance meter (CA-2000), the distance from the light incident surface side end of the light exit surface is 7.5 mm (evaluation system 1), 3 mm (evaluation system) The luminance profile L (X) (X axis: distance in the direction parallel to the light incident surface, Y axis: luminance L) in the direction parallel to the light incident surface (2A direction) of 2) is extracted. did.

In order to cancel the brightness gradient unrelated to the hot spot from each brightness profile L (X), the LED pitch P (in this case, about 18.8 mm (evaluation system 1) or 9.4 mm (evaluation system 2)). Value smoothed by taking the average value in the range corresponding to (moving average value)

  In the evaluation of the standard deviation value (SD value), the range of X is the range excluding the LEDs at both ends, that is, from the position of the second LED from the end of the point light source group. The position from the end to the position of the second LED is used.

(Evaluation of bright lines)
For the bright line (see FIG. 117 ), the LED is turned on, and the optical sheet laminated on the light exit surface of the light guide plate is visually observed from the normal direction of the light exit surface and from an oblique direction of 30 degrees from the normal direction. The presence or absence was judged.
In addition, the hot spot and the bright line were specifically evaluated according to the criteria of Table G-1.

[Table G-1]

2. Method for Producing Light Guide Plate of Production Example G The light guide plates of Production Examples G-1 to 15 and Production Examples G-22, 24, 26, 28, 30, and 32 are provided on a light guide plate substrate to be described later via an adhesive layer. It produced by bonding a light-diffusion layer.
Specifically, an acrylic pressure-sensitive adhesive film (PANAC) laminated on release paper on the surface opposite to the light diffusion layer of a light diffusion sheet (which is provided with a light diffusion layer on a base film) to be described later PD-S1 manufactured by Co., Ltd., pressure-sensitive adhesive film thickness: 25 μm, storage elastic modulus G ′ at 100 ° C .: 77,000 Pa) was laminated to produce a multilayer film with an adhesive layer. Next, after slitting the multilayer film with an adhesive layer with a predetermined width, the release paper of the adhesive layer was peeled off and bonded to the light incident surface of the light guide plate using a roller, and the light diffusion layer was bonded.
Production Examples G-21, 23, 25, 27, 29, and 31 were light guide plates in which a light diffusion layer was not bonded to the light incident surface, and the light guide plate base material was used as it was.

3. Explanation of used members Next, various members used in Production Example G will be described.
A. Optical sheet The following optical sheet was used in combination with the light guide plate.
(A) Diffusion sheet (DS) TDF-187 manufactured by Toray Sehan
(A) Prism sheet: LG Electronics SOS-07H
(C) Reflective polarizing sheet (DBEF): DBEF-D400 manufactured by 3M
These optical sheets were used by being laminated on the light exit surface of the light guide plate during measurement.
In Production Examples G-1 to G-5 and Production Examples G-21 to G-24, one DS was laminated as an optical sheet on the light exit surface of the light guide plate.
In Production Examples G-6 to 8 and Production Examples G-25 and 26, the DS and Prism (the prism rows are orthogonal to the LED arrangement direction) are stacked one by one on the light output surface of the light guide plate.
In Production Examples G-10, 11, 13-15, and Production Examples G-27, 28, 31, 32, the above DS and Prism (the prism row is orthogonal to the LED arrangement direction) on the light exit surface of the light guide plate And DBEF were laminated one by one in the order.
In Production Example G-12 and Production Examples G-29 and 30, Prism (the prism rows are parallel to the LED arrangement direction) and Prism (the prism rows are orthogonal to the LED arrangement direction) on the light exit surface of the light guide plate ) And DBEF.

B. Light Guide Plate Base In Production Example G, the following A and B were used as the light guide plate base. A and B are both 3 mm thick flat plates made of PMMA, and the first surface is provided with a lenticular lens shape extending in a direction perpendicular to the light incident surface.
・ Light guide plate base material-A
The first surface (light emitting surface) has a lenticular lens as shown in FIG. 119 A, the shape of the lenticular lens is the height 60 [mu] m, pitch 290 [mu] m. The second surface (opposite surface) has a dot pattern (starting from the inside 3 mm from the light incident surface) provided by printing white ink.
・ Light guide plate base material-B
The first surface (light emitting surface) has a lenticular lens as shown in FIG. 119 B, the shape of the lenticular lens is the height 80 [mu] m, pitch 290 [mu] m. The second surface (opposite surface) has a dot pattern (started from the inside 3 mm from the light incident surface) provided by laser engraving.

C. Light Diffusion Sheet The light guide plate of some Production Examples G was prepared by adhering the following film with a light diffusion layer (light diffusion sheet) to the light guide plate substrate light incident surface.
・ Light diffusion sheet 1
On the surface of a transparent base film made of polyethylene terephthalate with a thickness of 125 μm (A4300 manufactured by Toyobo Co., Ltd.), the first partial region and the second partial region having different light diffusion characteristics as shown in FIG. A light diffusing sheet having a light diffusing layer having a proportion equal to 50%. The light diffusing layer is UV-cured in which a plurality of recesses (grooves) having openings that are long in one direction (direction perpendicular to the longitudinal direction of the light incident surface (second direction)) are formed by speckle pattern exposure. It consists of resin hardened | cured material, and the average depth and average pitch of a recessed part differ in a 1st partial region and a 2nd partial region.
The diffusion angle of the entire light incident surface is 11 ° in the first direction and 1 ° in the second direction, and the range of emission angles with a peak intensity of 3/4 or more in the light emission pattern curve in the first direction is a normal distribution curve. The range of the emission angle with a peak intensity of 1/10 or more is 16% larger than that of the normal distribution curve ( FIG. 121 (a)).
Each partial region has the following characteristics.
(First partial area)
Each of the divided areas has an equal area of 1.65 square millimeters, an anisotropic light diffusion characteristic in which the diffusion angle in the first direction is 17 °, and the diffusion angle in the second direction is 1 °, Has an average pitch of 15 μm and an average depth of 8 μm.
(Second partial area)
The area of each divided region is equal to 1.65 square millimeters, has an anisotropic light diffusion characteristic in which the diffusion angle in the first direction is 8 °, and the diffusion angle in the second direction is 1 °, Has an average pitch of 25 μm and an average depth of 5 μm.

・ Light diffusion sheet 2
On a transparent base film (A4300, manufactured by Toyobo Co., Ltd.) made of polyethylene terephthalate having a thickness of 125 μm, the first partial region and the second partial region having different light diffusion characteristics as shown in FIG. A light diffusing sheet having a light diffusing layer having a ratio of the first partial region to 38% and the second partial region to 62%. The light diffusion layer is an ultraviolet curable resin cured product in which a plurality of concave portions having openings that are long in one direction (direction perpendicular to the longitudinal direction of the light incident surface (second direction)) is formed by speckle pattern exposure. Consists of.
The diffusion angle of the entire light diffusing layer is 6 ° in the first direction and 1 ° in the second direction, and the range of the emission angle with a peak intensity of 3/4 or more in the light emission pattern curve in the first direction is a normal distribution curve. The range of the emission angle that is 5% narrower than that and 1/10 or more of the peak intensity is 40% larger than that of the normal distribution curve ( FIG. 121 (b)).
Each partial region has the following characteristics.
(First partial area)
The area of each divided partial region is equal to 0.45 square millimeters, and has an anisotropic light diffusion characteristic in which the diffusion angle in the first direction is 10 ° and the diffusion angle in the second direction is 1 °, The average pitch of the recesses is 20 μm, and the average depth is 5 μm.
(Second partial area)
The area of each divided partial area is equal to 0.75 square millimeters, has an anisotropic light diffusion characteristic in which the diffusion angle in the first direction is 5 °, and the diffusion angle in the second direction is 1 °, The average pitch of the recesses is 33 μm and the average depth is 3 μm.

・ Light diffusion sheet 3
On a transparent base film (A4300, manufactured by Toyobo Co., Ltd., made of polyethylene terephthalate) having a thickness of 125 μm, the surface is uniformly subjected to speckle pattern exposure as shown in FIG. 123 (perpendicular to the longitudinal direction of the light incident surface) . A light diffusing sheet having a light diffusing layer made of an ultraviolet curable resin cured product in which a plurality of concave portions having openings having a long shape in the direction (second direction) is formed.
The diffusion angle of the entire light diffusion layer is 16 ° in the first direction and 1 ° in the second direction, and the range of the emission angle with a peak intensity of 3/4 or more in the light emission pattern curve in the first direction is a normal distribution curve. The range of the emission angle that is 8% larger than that and the peak intensity is 1/10 or more is 6% larger than that of the normal distribution curve ( FIG. 121 (c)).
The average pitch of the recesses is 5.2 μm, and the average depth is 1.2 μm.
・ Light diffusion sheet 4
On a transparent base film (A4300, manufactured by Toyobo Co., Ltd., made of polyethylene terephthalate) with a thickness of 125 μm, uniformly on the surface by speckle pattern exposure (direction perpendicular to the light incident surface longitudinal direction (second direction)) A light diffusing sheet having a light diffusing layer made of an ultraviolet curable resin cured product in which a plurality of recesses having long openings are formed.
The diffusion angle of the entire light diffusion layer is 14 ° in the first direction and 1 ° in the second direction, and the range of the emission angle with a peak intensity of 3/4 or more in the light emission pattern curve in the first direction is a normal distribution curve. The range of the emission angle that is 12.5% smaller than that and 1/10 or more of the peak intensity is 7.4% larger than that of the normal distribution curve ( FIG. 122 (d)).
The average pitch of the recesses is 3.5 μm, and the average depth is 1.2 μm.
・ Light diffusion sheet 5
On a transparent base film (A4300, manufactured by Toyobo Co., Ltd., made of polyethylene terephthalate) with a thickness of 125 μm, uniformly on the surface by speckle pattern exposure (direction perpendicular to the light incident surface longitudinal direction (second direction)) A light diffusing sheet having a light diffusing layer made of an ultraviolet curable resin cured product in which a plurality of recesses having long openings are formed.
The diffusion angle of the entire light diffusion layer is 25 ° in the first direction and 1 ° in the second direction, and the range of the emission angle with a peak intensity of 3/4 or more in the light emission pattern curve in the first direction is a normal distribution curve. The range of the emission angle that is 6% smaller than that and the peak intensity is 1/10 or more is equal to that of the normal distribution curve ( FIG. 122 (e)).
The average pitch of the recesses is 7.0 μm, and the average depth is 1.9 μm.

・ Light diffusion sheet A
Toray Saehan having a light diffusion layer on the transparent base film having a plurality of recesses (average pitch 16 μm, average depth 5 μm) having openings with isotropic shapes as shown in FIG. 124 on the surface . Diffusion sheet TDF-187

[Table G-2]

  Moreover, in addition to the determination based on the measuring instrument as described above in Production Example G, a combination suitable for the display device by visual determination (LED arrangement pitch, uneven structure on the light incident surface of the light guide plate, and lamination on the light guide plate) Examples of the combination of optical sheets) are as follows.

  The determination was performed according to the following criteria. It was judged comprehensively based on observations from all directions as to whether the display device was suitable for display.

In the standard model with a frame (horizontal distance between the light incident surface and the display area) G = 7 mm according to the above judgment criteria, suitable combinations considering the reduction of LEDs are shown in the table below for each optical sheet arrangement. Illustrate.
In the table, “light diffusion sheet” means a light diffusion sheet bonded to the light incident surface of the light guide plate substrate.

  Assuming a narrow frame with a frame G = 4 mm in accordance with the above criteria, suitable combinations that provide good quality will be exemplified below for each optical sheet arrangement.

<Production Example H>

  Production Example H will be described. In the following Production Example H, the major axis direction (the direction in which the diffusion angle is low) of the surface uneven structure of the diffusion sheet is installed perpendicular to the point light source array.

[Production Example H-1]
When producing the diffusion sheet according to Production Example H-1, the photosensitive medium is exposed and developed with the interference light diffused through the holographic diffuser described in Japanese Patent No. 3341519, thereby developing a speckle pattern. A sub-master type having a non-periodic surface uneven structure was produced. As a holographic diffuser when exposing the photosensitive medium, a diffusion plate having a diffusion angle in the direction horizontal to the diffusion sheet of 30 degrees and a diffusion angle in the vertical direction of 0.08 degrees was used. A photo-curing resin (adhesive for optics made by Norland) applied between the sub-master mold and the base material (toyobo PET base material A4300 having a thickness of 80 microns) so as to have a thickness of about 20 micrometers. After photocuring the agent NOA63), the sub-master mold was peeled to produce a diffusion sheet according to Production Example H-1 in which a surface layer having a surface uneven structure was formed on a substrate.

  The following five types of diffusion sheets were obtained by adjusting the size, shape and direction of the speckle pattern. The direction of the speckle pattern is adjusted in consideration of the vertical and horizontal directions of the diffusion sheet to be manufactured.

[Table H-1]

[Production Example H-2]
The minimum value of the diffusion angle of each diffusion sheet obtained in Production Example H-1 was measured using a beam profiler (NanoScan) manufactured by Photon Inc., and a helium neon (He-Ne) laser 1107P manufactured by JDS Uniphase. Was measured by irradiating from the surface of each diffusion sheet having a surface uneven structure, and the following results were obtained.

[Table H-2]

[Production Example H-3]
The maximum value of the diffusion angle of each diffusion sheet obtained in Production Example H-1 was measured using a variable angle photometer (GC-5000L) manufactured by Nippon Denshoku Industries Co., Ltd., and the light from the light source was applied to the surface of each diffusion sheet. When the measurement was performed by irradiating from the surface having the concavo-convex structure, the following results were obtained.

[Table H-3]

[Production Example H-4]
As shown in FIG. 126 , a line-shaped illumination system in which five point light sources 1 are arranged horizontally on the back surface of the diffusion sheet 2 with respect to the irradiation surface 3 was manufactured. The point light source 1 is an LED that emits parallel light having a wavelength of 488 nm, an output of 0.18 W, an intensity of Gaussian distribution, and a range of 1 / e ² of the maximum intensity of 3 mm. The distance between adjacent point light sources was 80 cm.

Using a 1936-C power meter manufactured by Newport, the 918D-UV-OD3 detector is used to irradiate the horizontal distribution of the irradiation light 4 on the irradiation surface 3 when the distance between the diffusion sheet 2 and the irradiation surface 3 is 1 m. Measurements were made at each point on the surface. 128 is a case where DS174-4 is used as the diffusion sheet 2, FIG. 129 is a case where DS175-1 is used, FIG. 130 is a case where DS175-2 is used, FIG. 131 is a case where DS176-1 is used, FIG. Is the intensity distribution when DS176-2 is used.

For comparison, the maximum and minimum values of the light intensity between the positions in FIG . 128 to FIG. 132 between −800 mm and 800 mm and the ratio of the minimum value to the maximum value of the light intensity were obtained. Results were obtained.

[Table H-4]

It can be seen that the ratio of the minimum intensity to the maximum intensity of light is 0.7 or more and the irradiation surface is illuminated in a uniform line shape, although the intensity is approximately 4 mW / cm ² or more regardless of which diffusion sheet is used. It was. In addition, DS174-4, DS175-1, and DS175-2 had good light intensity of 7.0 mW / cm ² or more even at the minimum value.

[Production Example H-5]
Of each diffusion sheet obtained in Production Example H-1, the surface unevenness of the diffusion sheet is obtained by sandblasting from the direction of 10 degrees obliquely with respect to the direction in which the diffusion angle of the emitted light of DS176-2 shows the minimum value. A streak pattern was formed on the surface having the structure. The processed diffusion sheet is designated DS176-2S.
About DS176-2S, when the pitch of the streak pattern was measured under an optical microscope,
The average pitch was 0.2 mm.

Next, a part of DS176-2S was cut, and the height of the streak pattern was measured from the cross-sectional shape. The average height was 0.02 mm.

[Production Example H-6]
When producing a diffusion sheet according to Production Example H-6, a photosensitive medium is exposed and developed with interference light diffused through a holographic diffuser described in Japanese Patent No. 3341519, thereby developing a speckle pattern. When producing a submaster mold having a non-periodic surface irregularity structure derived from it, the diffusion angle of the emitted light of the submaster mold is minimized by partially adjusting the size and shape of the speckle pattern during exposure. A sub-master type having a streak pattern in the direction of 8 degrees obliquely with respect to the direction indicating the value was obtained.

  Next, a diffusion sheet DS177-1V was obtained by transferring the pattern from the submaster mold obtained in this Production Example in the same manner as in Production Example H-1. Regarding DS1777-1V, the density pitch of the speckle pattern density was measured under an optical microscope, and the average pitch was 1 mm.

[Production Example H-7]
When the minimum value of the diffusion angle of the diffusion sheets obtained in Production Examples H-5 and 6 was measured in the same manner as in Production Example H-2, the following results were obtained.

[Table H-5]

[Production Example H-8]
When the maximum value of the diffusion angle of the diffusion sheets obtained in Production Examples H-5 and 6 was measured in the same manner as in Production Example H-3, the following results were obtained.

[Table H-6]

[Production Example H-9]
The diffusion sheets obtained in Production Examples H-1, 5, and 6 were subjected to a scratch resistance test in which a surface having a surface concavo-convex structure was rubbed with a pencil having a hardness of HB five times. The upper part of the pencil is sandwiched between two fingers and applied with a load of about 10 g so as to form an angle of about 30 degrees with respect to the surface of the test piece. Was moved at a speed of about 5 mm / sec. The results were as follows. In addition, (circle) in a table | surface represents that the damage | wound by rubbing with a pencil could not be visually recognized but was passed, and x represents that the damage | wound was visually recognizable and was unacceptable.

[Table H-7]

  It was found that the diffusion sheet having the streak pattern formed in the oblique direction has improved scratch resistance.

[Production Example H-11]
Similar to Production Example H-1, the following three types of diffusion sheets were obtained by adjusting the size, shape and direction of the speckle pattern. As a holographic diffuser for exposing the photosensitive medium, a diffusion plate having a diffusion angle in the vertical direction with respect to the horizontal plane of the screen and a diffusion angle in the horizontal direction was 5 degrees.

[Table H-8]

[Production Example H-12]
When the minimum value of the diffusion angle of each diffusion sheet obtained in Production Example H-11 was measured in the same manner as in Production Example H-2, the following results were obtained.

[Table H-9]

[Production Example H-13]
When the maximum value of the diffusion angle of each diffusion sheet obtained in Production Example H-11 was measured in the same manner as in Production Example H-3, the following results were obtained.

[Table H-10]

[Production Example H-14]
In the same manner as in Production Example H-4, the intensity distribution of the irradiation light 4 on the irradiation surface 3 was measured in the manufactured line illumination system. 133 shows the intensity distribution when DS142-8 is used as the diffusion sheet 2, FIG. 134 shows the intensity distribution when DS154-1 is used, and FIG. 135 shows the intensity distribution when DS156-1 is used.

For comparison, in the same manner as in Production Example H-4, the maximum and minimum values of the light intensity at positions in FIGS . 133 to 135 between −800 mm and 800 mm and the ratio of the minimum value to the maximum value were obtained. The following results were obtained. In DS 154-1 and DS 156-1, since the light is also diffused in the vertical direction, the maximum intensity in the horizontal direction is reduced as shown in Table H-11.

[Table H-11]

When DS142-8 was used for the diffusion sheet 2, the unevenness of the light intensity on the irradiated surface 3 was large, and it was unbearable. When DS154-1 and DS156-1 were used, the intensity was much less than 5 mW / cm ² , but the irradiated surface could not be illuminated sufficiently brightly.

<Production Example I>

  Next, Production Example I will be described.

  The optical film used in Production Example I has a plurality of openings having a long shape in one direction by speckle pattern exposure on the surface of a transparent base film (A4300, manufactured by Toyobo Co., Ltd.) made of polyethylene terephthalate and having a thickness of 125 μm. Acrylic pressure-sensitive adhesive film (Panac Co., Ltd.) laminated on release paper on the surface of the light diffusion sheet that has a light diffusion layer made of a cured UV-cured resin with depressions and does not have a light diffusion layer The product was manufactured by laminating PD-S1 manufactured by a company and a pressure-sensitive adhesive film thickness: 25 μm.

In Production Example I, the following operation was performed, and bubbles were observed visually.
Work 1: First, the release paper was peeled from the optical film. Next, both ends of the optical film were held by hand, and the angle with the one end surface of 713 mm × 3 mm of the light guide plate having a main surface of 713 mm × 410 mm and a thickness of 3 mm was adjusted. Next, the left end portion of the optical film was pressed onto one end surface of the light guide plate. Further, with the hand held at the right end of the optical film, a portion about 25 cm away from the left end of the optical film was pressed onto one end surface of the light guide plate (hereinafter referred to as “temporary sticking”). Thereafter, the optical film was pressed onto one end surface of the light guide plate at intervals of about 25 cm while moving the left hand about 25 cm. Finally, it was traced once while applying pressure to the optical film layer using a bonding jig.
Operation 2: The main surface has a rectangular shape of 713 mm × 410 mm, the light guide plates having a thickness of 3 mm are stacked in 25 layers, and the unevenness difference (displacement of the end surface) between the adjacent light guide plates is randomly 500 μm to 1 mm. The optical films were temporarily pasted one by one on a surface of 713 mm × 3 mm. After all 25 sheets were temporarily attached, 5-6 adjacent sheets were simultaneously traced once while applying pressure to the optical film layer using a bonding jig.

(Measurement of hardness)
The hardness of the elastic body was measured according to JIS K 6253. A type A durometer is typically used as a measuring instrument. For a porous material having a large pore size, such as a sponge, which is difficult to measure with a type A durometer, the rubber hardness with a type E durometer or the Asker C type durometer described in SRIS 0101 is measured and shown as the sponge hardness. .

(Production Example I-1)
In Production Example I-1, as a bonding jig, a silicone rubber Silastic J-RTV manufactured by Dow Corning was molded into a shape shown in FIG. 142 (rubber hardness 55), and a polyethylene vinyl as shown in FIG. What was wrapped in a bag and provided with slipperiness was used. The contact length of the bonding jig to the light guide plate in a state where pressure was applied was about 3 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind.

(Production Example I-2)
In Production Example I-2, as a bonding jig, Dow Corning's silicone rubber Silastic J-RTV was molded into the shape shown in FIG. 142 (rubber hardness 55), and as shown in FIG. (Registered trademark) was pasted to give slipperiness. The contact length of the bonding jig to the light guide plate in a state where pressure was applied was about 3 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind.

(Production Example I-3)
In Production Example I-3, as a bonding jig, a commercially available chloroprene rubber piece (3 mm × 50 mmφ, rubber hardness 62) was wrapped in a polyethylene plastic bag and provided with slipperiness. Although the rubber hardness of the bonding jig is high, it is thin, so that the contact length of the bonding jig to the light guide plate in a state where pressure is applied is as long as about 10 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind. Compared to Production Example I-1, the rubber hardness was high and the shape followability was slightly deteriorated. Therefore, a higher pressure was required, and workability was slightly deteriorated, but there was no problem.

(Production Example I-4)
In Production Example I-4, a sabo made by Sanshin Kosan Co., Ltd. (50 mm × 50 mm × 3 mm, rubber hardness 32) was wrapped in a polyethylene plastic bag and provided with slipperiness as a bonding jig. Since the bonding jig was soft and thin, the contact length of the bonding jig with respect to the light guide plate in a state where pressure was applied was as long as about 15 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind. Since the rubber hardness is lower than that of Production Example I-1, the efficiency with which the applied stress propagates to the stress in the direction perpendicular to the end face is reduced, so a higher pressure is required and workability is slightly deteriorated. There was no problem.

(Production Example I-5)
In Production Example I-5, VALQUA Code Seal Software (35 mm × 10 mm × 3 mm, rubber hardness 55) manufactured by Nippon Valqua Industries, Ltd. was used as a bonding jig. Since the plastic deformation property of the bonding jig was strong, the contact length of the bonding jig with respect to the light guide plate in a state where pressure was applied was as short as about 2 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind. Since it is a plastic deformation body as compared with Production Example I-1, the shape followability decreases and becomes harder each time it is used, so the life of the jig is slightly shorter, but there is no problem. .

(Production Example I-6)
In Production Example I-6, as a bonding jig, a commercially available EVA foam (95 mm × 25 mm × 10 mm, rubber hardness 28) was wrapped in a polyethylene plastic bag and provided with slipperiness. The rubber hardness of the bonding jig was low, but because of the thickness, the contact length of the bonding jig with respect to the light guide plate in a state where pressure was applied was as short as about 3 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind. Since the rubber hardness is lower than that of Production Example I-1, the efficiency with which the applied stress propagates to the stress in the direction perpendicular to the end face is reduced, so a higher pressure is required and workability is slightly deteriorated. There was no problem.

(Production Example I-7)
In Production Example I-7, as a bonding jig, a polyurethane resin (Seika No. 3 mm × 40 mmφ, rubber hardness 8) manufactured by Devica Co., Ltd. was wrapped in a polyethylene plastic bag and provided with slipperiness. Since the bonding jig is soft and thin, the contact length of the bonding jig with respect to the light guide plate in a state where pressure is applied was as long as about 15 mm.

  Air bubbles could be removed in both operations 1 and 2. In operation 2, the shape of the bonding jig was changed by applying pressure, and bubbles were eliminated as a result of pressure being applied to the light guide plate slightly behind. Since the rubber hardness is lower than that of Production Example I-1, the efficiency with which the applied stress propagates to the stress in the direction perpendicular to the end face is reduced, so a higher pressure is required and workability is slightly deteriorated. There was no problem.

(Production Example I-8)
In Production Example I-8, as a bonding jig, a silicone rubber Silastic J-RTV manufactured by Dow Corning was molded into a shape with a guide as shown in FIG. 145 (rubber hardness 55), as shown in FIG. Nichiban cellophane tape (registered trademark) was used to provide slipperiness. The contact length of the bonding jig with respect to the light guide plate in a state where pressure was applied was about 8 mm.

  In operation 1, bubbles could be removed. In operation 2, since the guide shape interfered with the light guide plate, the bubbles could not be removed.

(Production Example I-11)
In Production Example I-11, as a bonding jig, a commercially available bamboo spatula (rubber hardness 98) was bonded to a cello tape (registered trademark) manufactured by Nichiban Co., Ltd. to give a slip property. The contact length of the bamboo spatula with the light guide plate under pressure was 0.3 mm.

  In operation 1, in the process of tracing the optical film layer, the jig was inclined and the contact area decreased, so that the bubbles could not be removed successfully. In the operation 2, since there is no shape following property, the bubbles in the light guide plate slightly recessed cannot be removed.

(Production Example I-12)
In the case of using a bonding jig such as Production Example I-8, a work for removing bubbles can be performed only for each light guide plate (because it cannot be applied to work 2), and thus a plurality of sheets were laminated. In order to remove air bubbles from the light guide plate in a state, it is necessary to individually remove the air bubbles one by one, and the workability for removing the air bubbles is complicated. Therefore, operation 2 was performed using a rubber roller having a width substantially the same as the thickness of the light guide plate as shown in FIG . Air bubbles could be efficiently removed by rubbing along the light incident surface of the light guide plate in a state where the rollers were stacked. In particular, as the material constituting the roller surface, it was most preferable to use a material made of a soft material such as rubber so that the surface slips.
(Production Example I-13)
As a bonding jig, operation 2 was performed using three rollers arranged in parallel as shown in FIG. 148 (the same rollers as those in FIG. 147 ). Specifically, in the form as shown in FIG. 149 , the work was performed by rubbing the roller against the light incident surface of the light guide plate. As a result, the bubbles could be removed efficiently. When this bonding jig was used, bubbles were removed continuously by three rollers only by performing a tracing operation once, so that the efficiency of removing bubbles was improved.

The surface light source device of the present invention can be used for various display devices such as notebook PCs, portable information terminals, desktop PC monitors, digital cameras, and general lighting devices.
In particular, the surface light source device of the present invention is large and thin because a plurality of point light sources are used as a light source, and luminance unevenness (hot spots) in the vicinity of the light incident surface is small and uniform luminance can be obtained over the entire light exit surface. The liquid crystal display device (television receiver) can be provided at low cost and / or in a narrow frame. In addition, since uniform light emission can be obtained over a wide range, natural lighting that does not give a sense of discomfort or discomfort even when looking directly can be realized, so (indoor) ceiling lighting and its external shape are strictly regulated by law. It is also suitable for the evacuation guide lights specified in the above.

DESCRIPTION OF SYMBOLS 1 Light guide plate 11 Light exit surface 12 Light entrance surface 13 Groove 14 Thickness direction 15 of a light guide plate 16 Direction parallel to a light exit surface 16 Normal direction 41 of a light entrance surface Transparent substrate 42 Transfer roller 5a It has a layer in which the groove structure was formed. Multilayer film 5b Multilayer film 51 having a layer having a groove structure Release film 52 Adhesive layer 53 Base film 54 Layer having a groove structure 55 Adhesive layer 56 Mount film 61 Groove 71 Multilayer having a layer having a groove structure Film 72 Roll 9 Surface light source device 91 Light guide plate 92 Point light source 93 Light incident surface 94 Area corresponding to display area 10 LED
DESCRIPTION OF SYMBOLS 101 Light emission surface 102 Width of light emission surface 11 Liquid crystal display panel 112 Display area 113 Black matrix 114 Source chip 115 Gate chip 12 Television receiver 121 Display device 122 Front cabinet 1221 Speaker 123 TV tuner circuit board 124 Power supply circuit board 125 Control circuit board 126 Back cabinet 127 Stand 26 Specific dot 26a-f Vertical bisector 262 of the line segment which connects the center point of a specific dot and the center point of an adjacent dot Polygon AF surrounding a specific dot Adjacent dot G Horizontal distance P between light incident surface of light guide plate and display area Pitch arrangement of point light source B1 Light source B2 Optical sheet B11 Linear light source (cold cathode tube (CCFL))
B12 Point light source (LED)
B13 Reflective sheet B14 Optical sheet, diffusion plate B15 Diffusion sheet B16 Surface-shaped diffusion sheet B17 Prism sheet B18 Reflective polarization sheet B101 Cold cathode tube (CCFL)
B102 LED
B103 Projection area directly above the light source B104 Projection area between the light sources B301 High diffusion angle area B302 Low diffusion angle area B303 High diffusion angle area B304 Low diffusion angle area C2-9 Illuminator C2-90 Frame C2-901 Opening C2-91 Light plate E28 Light guide member E281a Light incident portion E281b Light incident portion E282 Light exit surface E283 Light guide surface E41 Base material E42 Adhesive layer E43 Light diffusion layer G2 Light guide plate G21 First surface G22 Light incident surface G23 Groove G24 Light incident surface longitudinal direction ( (First direction)
G25 Direction perpendicular to light incident surface longitudinal direction (second direction)
H1 Point light source H2 Diffusion sheet H3 Irradiation surface H4 Irradiation light H5 Diagonal streak pattern H6 A direction H7 that gives the minimum value of the diffusion angle of the emitted light H7 A streak pattern 5 with respect to the direction 6 that gives the minimum value of the diffusion angle of the emitted light Angle I1. . . Plate member I2. . . Tape-like member I3. . . Marking I4. . . Bonding jig I5. . . Release paper I6. . . Contact part I7. . . Slip property imparting layer I8. . . Shape following layer I9. . . Pinch roller I10. . . Guide roller J1 Vertical groove sheet roll J2 Adhesive vertical groove sheet roll J21 Adhesive vertical groove sheet roll (TD direction high diffusion)
J22 Vertical groove sheet roll with adhesive (MD direction high diffusion)
J221 Small roll with fluted sheet roll with adhesive (MD high diffusion)
J222 Half slit roll roll J3 Longitudinal groove sheet with adhesive (sheet-fed)
J31 Vertical groove sheet with marking J4 Half slit sheet (sheet-fed)
J41 Half slit sheet with marking (sheet-fed)
J42 Slit white stripped half slit sheet (single wafer)
J43 Marking Slit white stripped half slit sheet (single wafer)
J5 Vertical groove seal with adhesive (strip)
J6 Slit spanning heavy release separator

Claims (40)

A light guide plate having a light exit surface, a facing surface facing the light exit surface, and at least one light incident surface sandwiched between the light exit surface and the facing surface, and the at least one light entrance of the light guide plate A surface light source device having a plurality of point light sources arranged in the vicinity of the light surface;
A display panel that is disposed so as to face the light exit surface of the light guide plate and that displays by adjusting the transmission of light, and a display panel having a light shielding frame that defines the display area;
A tuner for receiving broadcast video signals;
A television receiver comprising:
The television receiver, wherein the at least one light incident surface of the light guide plate has a plurality of concave portions or convex portions having an anisotropic shape whose opening or bottom surface is long in a direction perpendicular to the light outgoing surface. The light exit surface and / or the facing surface of the light guide plate are
In the region B in the vicinity of the light incident surface of the light shielding portion that is shielded by the light shielding frame, the light scattering degree of the partial region that faces the point light source is light scattering in the partial region that faces the portion between the point light source and the point light source. The television receiver according to claim 1, further comprising a light scattering process configured to be lower than a degree. The light exit surface and / or the facing surface of the light guide plate further has a light scattering process in a region A that covers a non-light-shielding portion that is not shielded by the light-shielding frame,
In a region C sandwiched between the region A and a region B in the vicinity of the light incident surface of the light-shielding part that is shielded by the light-shielding frame, at least a partial region that faces the part between the point light source and the point light source. The television receiver according to claim 2, wherein no light scattering processing is provided.   The light scattering processing applied to the partial region facing the portion between the point light source and the point light source in the region B near the light incident surface of the light shielding portion shielded by the light shielding frame is an intermediate position between the point light source and the point light source. The television receiver according to claim 2, wherein the television receiver has a gradation in which the light scattering degree increases toward the screen.   In the region A that covers the non-light-shielding portion that is not shielded by the light-shielding frame on the light exit surface and / or the opposing surface of the light guide plate, the light scattering degree of the partial region that faces the point light source, the point light source, and the point light source The television receiver according to any one of claims 1 to 4, wherein a light scattering degree of a partial region directly facing a portion between is substantially equal.   Light scattering of a partial region facing the portion between the point light source and the point light source in the region B near the light incident surface of the light shielding portion shielded by the light shielding frame on the light exit surface and / or the opposing surface of the light guide plate The television receiver according to any one of claims 1 to 5, wherein the degree is 2 to 20 times the light scattering degree in the region A covering the non-light-shielding portion. The plurality of point light sources are arranged at substantially equal intervals, and the arrangement pitch P and the horizontal distance G between the at least one light incident surface and the display area satisfy the following relationship: 2. A television receiver according to claim 1.
P / G> 1.0   When the plurality of point light sources are turned on, a front side of a substantially rectangular boundary between a light shielding portion shielded by the light shielding frame and a non-light shielding portion not shielded by the light shielding frame on the light exit surface 8. The standard deviation of a value obtained by dividing the measured value of luminance at each measurement point on the one side closest to the light incident surface substantially parallel to the entry light surface by an average value is 0.02 or less. The television receiver according to item 1.   The light guide plate has a base material, an adhesive layer laminated on at least one end surface of the base material, and an anisotropic shape which is laminated on the adhesive layer and has a long opening or bottom in one direction on the surface. The television receiver according to claim 1, further comprising: a layer having a plurality of concave portions or convex portions.   The television receiver according to claim 9, wherein the adhesive layer is made of a material having a storage elastic modulus G ′ at 100 ° C. of 10,000 to 45,000 Pa. The layer having a plurality of recesses or projections having an anisotropic shape with an opening or bottom surface extending in one direction on the surface has a base film layer and an anisotropic shape with an opening or bottom surface extending in one direction on the surface. It consists of a resin layer having a plurality of recesses or protrusions,
A resin layer having a plurality of recesses or protrusions having an anisotropic shape with an opening or bottom surface extending in one direction on the surface,
Photopolymerizable resin containing (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group: 70 to 99.9% by mass, and (B) photopolymerization initiator: 0.1 to 30% by mass Consisting of a cured product of the composition,
The (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group includes a compound having a structure represented by the following general formula (I) having a biphenyl group. TV receiver.
Formula (I)
(In the formula, R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.) The television receiver according to claim 11, wherein the compound having a structure represented by the general formula (I) has a structure represented by the following general formula (II).
Formula (II)
(In general formula (II), R represents a hydrogen atom or a methyl group, A independently represents an alkylene group having 1 to 4 carbon atoms, and n represents an integer of 1 to 3).   The adhesive layer and the surface having a plurality of recesses or protrusions having an anisotropic shape with an opening or bottom surface extending in one direction on the surface have a slipperiness-imparting layer made of a slip-providing material on the surface, Bonded to one end surface of the base material using a bonding jig having a shape following layer made of a material having a shape following property and having a rubber hardness of 10 to 70 located inside the slipperiness-imparting layer The television receiver according to claim 9, wherein The adhesive layer and a layer having a plurality of recesses or protrusions having an anisotropic shape having a long opening or bottom surface in one direction on the surface were bonded to one end surface of the substrate by the following bonding method. The television receiver according to claim 9, wherein the television receiver is:
A laminated body in which an adhesive layer and a layer having a plurality of concave portions or convex portions on the surface are laminated, and a laminated body having a width substantially the same as or narrower than the thickness of the one end face of the substrate is prepared. Process,
A laminating step in which the adhesive layer of the laminate is opposed to the one end surface, and the laminate is laminated on the one end surface;
A bonding jig comprising a member having shape following characteristics, wherein the opening or bottom surface has a long anisotropic shape in one direction on the surface having a plurality of concave portions or convex portions, and the longitudinal direction of the one end surface An adhesion process that traces at least once while applying pressure to
A laminating method.   Diffusion in a direction perpendicular to the one direction when a light beam is incident on the surface having a plurality of recesses or protrusions having an anisotropic shape with an opening or bottom surface extending in one direction from the normal direction. The television receiver of any one of Claims 9-14 whose angle is 65 degrees or more.   Diffusion in a direction parallel to the one direction when light rays are incident from the normal direction to a layer having a plurality of recesses or projections having an anisotropic shape with an opening or bottom surface extending in one direction on the surface. The television receiver of any one of Claims 9-15 whose angle is 5 degrees or less.   The light incident surface has a direction in which a diffusion angle of outgoing light of light incident from the normal direction thereof shows a maximum value and a direction in which the minimum value is shown, and the ratio of the maximum value to the minimum value is 200 or more. The television receiver of any one of Claims 1-16 which exists.   The television receiver according to claim 1, wherein an average pitch in a direction parallel to the light exit surface of the plurality of concave portions or convex portions of the light incident surface is 100 μm or less.   19. The television receiver according to claim 1, wherein at least one of the plurality of concave portions or convex portions is irregularly different among a cross-sectional shape, a depth or a height, and a pitch. A light guide plate having a light exit surface, a facing surface facing the light exit surface, and at least one light incident surface sandwiched between the light exit surface and the facing surface;
A frame defining a light emitting area of the surface light source device, disposed on the light exit surface side of the light guide plate;
A plurality of point light sources arranged in the vicinity of the at least one light incident surface of the light guide plate;
A surface light source device comprising:
The surface light source device, wherein the at least one light incident surface of the light guide plate has a plurality of concave portions or convex portions having an anisotropic shape whose opening or bottom surface is long in a direction perpendicular to the light output surface. The light exit surface and / or the facing surface of the light guide plate are
In the region B in the vicinity of the light incident surface of the light shielding portion that is shielded by the frame, the light scattering degree of the partial region that faces the point light source is the light scattering degree of the partial region that faces the portion between the point light source and the point light source. The surface light source device according to claim 20, wherein the surface light source device has a light scattering process configured to be lower. The light exit surface and / or the facing surface of the light guide plate further has a light scattering process in a region A that covers a non-light-shielding portion that is not shielded by the frame,
In the region C sandwiched between the region A and the region B in the vicinity of the light incident surface of the light shielding portion shielded by the frame, at least the partial region directly facing the portion between the point light source and the point light source The surface light source device according to claim 21, wherein no light scattering processing is provided.   The light scattering processing applied to the partial region facing the portion between the point light source and the point light source in the region B in the vicinity of the light incident surface of the light shielding portion shielded by the frame is at an intermediate position between the point light source and the point light source. The surface light source device according to claim 21 or 22, wherein the surface light source device has a gradation in which the degree of light scattering increases.   In the region A that covers the light exit surface of the light guide plate and / or the non-light-shielded portion that is not shielded by the frame, the light scattering degree of the partial region directly facing the point light source, the point light source and the point light source The surface light source device according to any one of claims 20 to 23, wherein the degree of light scattering of a partial region facing the portion in between is substantially equal.   Light scattering degree of a partial region facing a portion between the point light source and the point light source in the region B in the vicinity of the light incident surface of the light shielding portion shielded by the frame on the light exit surface and / or the opposing surface of the light guide plate The surface light source device according to any one of claims 20 to 24, wherein the surface light source device has a light scattering degree of 2 to 20 times in a region A covering the non-light-shielding portion. The plurality of point light sources are arranged at substantially equal intervals, and the arrangement pitch P and the horizontal distance G between the at least one light incident surface and the display area satisfy the following relationship: The surface light source device according to claim 1.
P / G> 1.0   When the plurality of point light sources are turned on, the light incident surface is one side of a substantially rectangular boundary between a light shielding portion shielded by the frame and a non-light shielding portion not shielded by the frame. 27. The standard deviation value of a value obtained by dividing a measured value of luminance at each measurement point on the one side closest to the light incident surface by an average value substantially parallel to the surface is 0.02 or less. The surface light source device according to item.   The light guide plate has a base material, an adhesive layer laminated on at least one end surface of the base material, and an anisotropic shape which is laminated on the adhesive layer and has a long opening or bottom in one direction on the surface. The surface light source device of any one of Claims 20-27 which has a layer which has a several recessed part or convex part which has.   The surface light source device according to claim 28, wherein the adhesive layer is made of a material having a storage elastic modulus G ′ at 100 ° C. of 10,000 to 45,000 Pa. The layer having a plurality of recesses or projections having an anisotropic shape with an opening or bottom surface extending in one direction on the surface has a base film and an anisotropic shape with an opening or bottom surface extending in one direction on the surface. It consists of a resin layer having a plurality of recesses or protrusions,
A resin layer having a plurality of recesses or protrusions having an anisotropic shape with an opening or bottom surface extending in one direction on the surface,
Photopolymerizable resin containing (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group: 70 to 99.9% by mass, and (B) photopolymerization initiator: 0.1 to 30% by mass Consisting of a cured product of the composition,
30. The (A) addition polymerizable monomer having at least one terminal ethylenically unsaturated group includes a compound having a structure represented by the following general formula (I) having a biphenyl group. Surface light source device general formula (I)
(In the formula, R represents a hydrogen atom or a methyl group, and X represents a divalent organic group having at least part or all of an alkylene group.) The surface light source device according to claim 30, wherein the compound having a structure represented by the general formula (I) has a structure represented by the following general formula (II).
Formula (II)
(In general formula (II), R represents a hydrogen atom or a methyl group, A independently represents an alkylene group having 1 to 4 carbon atoms, and n represents an integer of 1 to 3).   The adhesive layer and the surface having a plurality of recesses or protrusions having an anisotropic shape with an opening or bottom surface extending in one direction on the surface have a slipperiness-imparting layer made of a slip-providing material on the surface, Bonded to one end surface of the base material using a bonding jig having a shape following layer made of a material having a shape following property and having a rubber hardness of 10 to 70 located inside the slipperiness-imparting layer The surface light source device according to any one of claims 28 to 31. The adhesive layer and a layer having a plurality of recesses or protrusions having an anisotropic shape having a long opening or bottom surface in one direction on the surface were bonded to one end surface of the substrate by the following bonding method. The surface light source device according to any one of claims 28 to 32, wherein:
A laminated body in which an adhesive layer and a layer having a plurality of concave portions or convex portions on the surface are laminated, and a laminated body having a width substantially the same as or narrower than the thickness of the one end face of the substrate is prepared. Process,
A laminating step in which the adhesive layer of the laminate is opposed to the one end surface, and the laminate is laminated on the one end surface;
A bonding jig comprising a member having shape following characteristics, wherein the opening or bottom surface has a long anisotropic shape in one direction on the surface having a plurality of concave portions or convex portions, and the longitudinal direction of the one end surface An adhesion process that traces at least once while applying pressure to
A laminating method.   Diffusion in a direction perpendicular to the one direction when a light beam is incident on the surface having a plurality of recesses or protrusions having an anisotropic shape with an opening or bottom surface extending in one direction from the normal direction. The surface light source device according to any one of claims 28 to 33, wherein the angle is 65 ° or more.   Diffusion in a direction parallel to the one direction when light rays are incident from the normal direction to a layer having a plurality of recesses or projections having an anisotropic shape with an opening or bottom surface extending in one direction on the surface. The surface light source device according to any one of claims 28 to 34, wherein the angle is 5 ° or less.   The light incident surface has a direction in which a diffusion angle of outgoing light of light incident from the normal direction thereof shows a maximum value and a direction in which the minimum value is shown, and the ratio of the maximum value to the minimum value is 200 or more. The surface light source device according to any one of claims 20 to 35.   The surface light source device according to any one of claims 20 to 36, wherein an average pitch in a direction parallel to the light exit surface of the plurality of concave portions or convex portions of the light incident surface is 100 µm or less.   The surface light source device according to any one of claims 20 to 37, wherein at least one of the plurality of concave portions or convex portions is irregularly different among a cross-sectional shape, a depth or a height, and a pitch.   Indoor ceiling lighting comprising the surface light source device according to any one of claims 20 to 38. 40. The indoor ceiling illumination according to claim 39, wherein the maximum luminance of the light-emitting surface at the time of lighting is 10,000 cd / m ² or less.