JP2012079676A - Light guide member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide member which has little luminance unevenness (hot spots) generated in the vicinity of a light-incident part and has a uniform luminance distribution in almost all regions of an emitting face even in case it is used in combination with a plurality of point light sources, and which can emit light of the small number of point light sources from a wide range.SOLUTION: The light guide member has a light-emitting face and at least one light-incident part, and at least that one light-incident part has a plurality of recessed parts or projection parts which have fine concavo-convex structures on the surface.

Description

  The present invention relates to a light guide member, for example, various lighting devices such as a so-called edge light type surface light source device, a vehicle signal lamp such as a headlight and a tail lamp, and a vehicle interior lighting device such as a vehicle interior light that illuminates the interior of the vehicle. It is related with the light guide member which can be used for.

  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. 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 light exit surface, a facing surface facing the light exit surface, and at least one light incident portion sandwiched between the light exit surface and the facing surface, and is incident from a side portion (light entrance portion). 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.

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 place away from the light source to some extent), but in the vicinity of the light entrance near the light source, the light source While the intervening portion is dark, an extremely bright so-called hot spot appears immediately in front of the light source, resulting in luminance unevenness.
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 provided with a symmetrical triangular shape in a light incident portion, and Patent Document 3 includes an opening portion in a light incident portion. 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 opposing surface and periodically finely cut such as a lenticular shape on the light incident portion. A light guide plate provided with an anisotropic light diffusing adhesive layer comprising an adhesive and a needle-like filler is disclosed.

In addition, since point light sources (solid light emitting devices such as light emitting diodes (LEDs), semiconductor laser diodes (LD), and electroluminescent devices (EL)) can obtain high-intensity light with low power, It is also used as a light source.
A vehicular lamp needs to illuminate a wide area, but a point light source is usually used in combination with a light guide member because it has a small light emitting area. As the light guide member used in the vehicle lamp, the side portion similar to that of the light guide plate used in the surface light source device described above is used as the light entrance portion (the light entrance portion is adjacent to the light exit surface (contacts the light exit surface). And the like, and the light incident part is present on the surface facing the light exit surface.
As the former, Patent Document 6 discloses that a plurality of LEDs are arranged on a side end surface (light incident surface) of a light guide plate and used as a vehicle interior lamp. In such a vehicle interior light, there is a defect that uneven brightness occurs as in the case of the edge light type surface light source device described above. In the technique disclosed in Patent Document 6, the light guide plate Luminance unevenness is improved by providing a plurality of grooves having a semicircular cross section on the reflecting surface facing the light exit surface.
As the latter, Patent Document 7 discloses that a point light source is disposed behind a light guide inner lens disposed along a front lens and used as a vehicle signal lamp such as a side turn signal lamp. .

However, the light guide members disclosed in Patent Documents 1 to 6 do not sufficiently improve luminance unevenness when used in combination with a plurality of point light sources, and cannot eliminate hot spots in the vicinity of the light incident portion. .
Furthermore, since the technology disclosed in Patent Documents 2 and 3 has a complicated structure of unevenness and depression formed in the light incident portion, it corresponds to a small LED having a light emitting surface width of 5 mm or less that has been used in recent years. It is difficult to provide a sufficient number of irregularities and depressions on the light emitting surface. In addition, the technique disclosed in Patent Document 4 needs to be knurled on the opposite surface of the light guide member, so that it is difficult to apply to a light guide member used in a large-sized liquid crystal television, and the cost is also low. Take it. 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 immediately after light-guide member incident light Therefore, the quality of light used for a display device cannot be obtained.

  In addition, the vehicular lamp disclosed in Patent Document 7 has another problem that the entire light exit surface of the light guide inner lens cannot emit light.

  As described above, when the light guide member is used in combination with a plurality of point light sources, there is a problem of occurrence of luminance unevenness (hot spot) in the vicinity of the light incident portion, and in combination with a small number of point light sources. When used, there is a problem that it is difficult to obtain a wide light emitting area.

  Moreover, as a general problem when using the light guide member, reflection at the light incident part (difference in refractive index between air and light constituting the light guide member when light enters the light guide member) It is possible to reduce incident surface reflection) and efficiently use incident light. As a general technique for reducing reflection (also simply referred to as “antireflection”), it is known that antireflection processing is performed on a portion where reflection is a problem (for example, Non-Patent Document 1). It has also been proposed to apply an antireflection process to the light incident part (Patent Documents 8 and 9). However, when the light incident portion is processed to prevent luminance unevenness as in the techniques disclosed in Patent Documents 2 to 5, the light incident portion is further subjected to antireflection processing in addition to these luminance unevenness prevention processing. Therefore, it is difficult to achieve both luminance unevenness prevention and reflection prevention.

JP 2003-107247 A JP 2002-169034 A JP 2003-215346 A JP 2006-49286 A JP 2008-34234 A JP 2000-127847 A JP 2010-52566 A JP 2006-147444 A JP 2006-156061 A

“Roll-to-Roll moth eye AR film using Blu-ray Disc technology”, Monthly Display, 2010, July, p. 51-58

The present invention has been made in view of the above points. In the case of using in combination with a plurality of point light sources while reducing the reflection at the light incident portion and efficiently using incident light, the present invention has been made. It is an object of the present invention to provide a light guide member that hardly causes luminance unevenness (hot spot) in the vicinity of the light portion and that can realize a uniform luminance distribution over almost the entire light emitting surface.
It is another object of the present invention to provide a light guide member capable of obtaining a wide light emitting area when used in combination with a small number of point light sources while efficiently reducing incident light and reducing incident light. .

  As a result of intensive studies on the light guide member, the present inventors can reduce reflection at the light incident portion by providing a plurality of concave portions or convex portions having a fine concavo-convex structure on the light incident portion of the light guide member. In addition, the incident light can be diffused at a wide angle, and as a result, the unevenness in brightness caused by hot spots and other point light sources can be eliminated, and a wide light emitting area can be obtained even with a small number of point light sources. I found.

That is, the present invention is as follows. A light guide member having a light exit surface and at least one light incident portion,
The light guide member, wherein the at least one light incident portion has a plurality of concave portions or convex portions having a fine concavo-convex structure on a surface thereof.

  If the light guide member of the present invention is used, the reflection at the light incident part can be reduced and the incident light can be used efficiently, and even when a point light source is used as the light source, there is almost no luminance unevenness and the light exit surface of the light guide member A surface light source device having a display area having substantially the same area can be provided.

It is the schematic of an example of the light guide member of this invention. It is a surface profile figure which shows an example (groove structure) of several recessed part or convex part formed in the light-incidence part of the light guide member of this invention. It is a surface profile figure which shows an example (groove structure) of several recessed part or convex part formed in the light-incidence part of the light guide member of this invention. It is explanatory drawing of the specific example of the manufacturing method of several recessed part or convex part which has a fine uneven structure on the surface. It is sectional drawing of the multilayer film for light guide member manufacture which formed the several recessed part or convex part which has a fine uneven structure on the surface. It is the schematic of the sealing sheet of the multilayer film (seal | sticker) for light guide member formation which formed the some recessed part or convex part which has a fine uneven structure on the surface. It is explanatory drawing of the specific example of the manufacturing method of the multilayer film (tape) for light guide member which formed the several recessed part or convex part which has a fine uneven structure on the surface. 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 of this invention, and a vehicle illuminating device. It is the front schematic of the liquid crystal display panel using the light guide member of this invention. It is a figure which shows the structure of the television receiver of this invention. It is explanatory drawing of the pitch and depth of the recessed part which the light guide member of this invention has in a light-incidence part. The microscope picture which shows an example of the recessed part formed in the light-incidence part of the light guide member of this invention. Transmitted light in a direction perpendicular to the major axis of the opening of the concave portion of the light incident on the multilayer film (seal) for manufacturing the light guide member having a plurality of concave portions having a fine concavo-convex structure on the surface. It is an angle distribution map of intensity. It is a photograph of the specific example of a moth eye structure. It is a photograph of the specific example of the several recessed part which has a moth eye structure on the surface. It is a photograph of a plurality of grooves which have a fine uneven structure on the surface in an example. It is a photograph of a plurality of grooves which have a fine uneven structure on the surface in an example. It is a photograph of the fine uneven structure in an Example. It is a graph which shows the reflectance of the light of wavelength 380-780 nm of a TAC film. It is a graph which shows the reflectance of the light of wavelength 380-780 nm at the time of forming a moth-eye structure on a TAC film. It is a graph which shows the comparison of the in-plane average brightness | luminance of standard reference B, Example B, Comparative example B, and Reference example B. 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 which has a fine uneven structure on the surface. It is a figure which shows the luminance distribution of Example A and Comparative Examples A1-A3. It is a figure which shows an example of the preferable light-scattering pattern of an opposing surface. It is a schematic sectional drawing of an example of the light guide member of this invention. It is sectional drawing of an example of a vehicle-mounted illuminating device.

An embodiment of the light guide member of the present invention will be specifically described below with reference to FIG. 1 showing a schematic diagram of an example of the light guide member of the present invention.
The light guide member 1 of the present invention has a light exit surface 11 and at least one light incident portion 12.
In the light guide member of FIG. 1, light from a light source disposed in the vicinity is incident on the light guide member 12 from the light incident portion 12, and is repeatedly reflected inside the member to guide the light. The light is emitted from the light exit surface 11 to the outside toward the light exit surface 11 by an opposing surface (not shown).
The light guide member of FIG. 1 has a flat plate shape, and the light incident portion is present on the side of the light exit surface (the surface in contact with the light exit surface). The position (positional relationship with the light exit surface) does not have to be as described above. For example, it has a shape curved along the outer shape of the illuminating device main body as shown in FIG. 28, and the light incident portions 281a and 281b emit light. It may be present on the side of the facing surface 283 that faces the surface 282.

The light guide member of the present invention has a plurality of concave portions or convex portions 13 having a fine concavo-convex structure on the surface in the light incident portion 12.
In the light guide member 1 of FIG. 1, the plurality of concave portions or convex portions are parallel (substantially parallel) to the thickness direction 14 of the light guide member (in other words, perpendicular (substantially vertical) to the major axis direction 15 of the light exit surface 11. It is a groove.

The light guide member of the present invention has a plurality of concave portions or convex portions (first irregularities) in the light incident portion, and further has a fine concave-convex structure (second irregularities) on the surface of the plurality of concave portions or convex portions. Have irregularities). That is, the light guide member of the present invention has a structure in which the concave and convex structure is doubled in the light incident portion.
The plurality of concave portions or convex portions provided in the light incident portion play a role of wide-angle diffusion of incident light, and the fine concavo-convex structure further provided on the surface reflects the light incident on the light incident portion. Prevents (reduces) and increases the efficiency of use of incident light.

First, a plurality of concave portions (convex portions) (first concave portions) (first concave portions) provided in the light incident portion (having a fine uneven structure on the surface) will be described.
The shape and size (depth and height) of each concave portion (convex portion) of the plurality of concave portions (convex portions) provided in the light incident portion may be the same or different from each other. Moreover, each recessed part (convex part) may be arrange | positioned periodically and may be arrange | positioned at random. However, from the viewpoint of preventing luminance unevenness, the plurality of concave portions (convex portions) are parallel to the shape, size (depth, height), and the long axis direction of the light exit surface, rather than having a periodic structure. A random structure in which at least one of the pitch in the direction 15 and the pitch in the direction parallel to the major axis direction of the light incident portion is randomly (irregularly) different is preferable.
Here, the size (or pitch) being different means that when a plurality of sizes (or pitches) are measured, the value obtained by multiplying the standard deviation by 3 (3 sigma) exceeds 10% of the average value. Say. The major axis direction of the light exit surface (light entrance portion) is a line segment that is formed when the light exit surface (light entrance portion) crosses the light exit surface (light entrance portion) through the center of gravity when the light exit surface (light entrance portion) is captured as a figure. The direction of the axis orthogonal to the shortest of the two. When the light exit surface (light entrance portion) is a curved surface, the major axis direction is a straight line connecting the intersections of the major axis and the light exit surface (light entrance portion) directly (with the shortest distance outside the curved surface). The direction of

  There is no limitation on the shape of each concave portion (convex portion), for example, (reverse) hemisphere, (reverse) hemispherical sphere, (reverse) polygonal column, (reverse) polygonal pyramid, (reverse) polygonal frustum, etc. It may be indefinite shape. Moreover, each recessed part (convex part) can be made into a groove | channel or a ridge. In the case of the groove (畝), the cross-sectional shape is not limited, and for example, it can be (reverse) V-shaped or (reverse) U-shaped, and the cross-sectional shape or width is the extending direction of the groove (畝) It may change along.

Each concave portion (convex portion) has an anisotropic shape whose opening (bottom surface) is long in one direction, and a plurality of concave portions (convex portions) have a major axis of the opening (bottom surface) in the same direction (specifically Is arranged in an orientation that is substantially parallel to a direction (perpendicular to the direction in which it is desired to spread (expand)) the light emitted from the point light source, that is, a plurality of concave (convex) openings. It is preferable that the portion (bottom surface) has an anisotropic shape that is long in one specific direction because incident light is likely to diffuse in a direction orthogonal to the specific one direction, and the effect of reducing luminance unevenness is improved. . 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).
In addition, when the angle | corner which the major axis of the opening part (bottom surface) of several recessed parts (convex part) makes is 40 degrees or less (even if it is not 0 degree | times), the opening part of several recessed parts (convex part) ( The bottom surface) has “a long anisotropic shape in one specific direction”, but the angle formed by the long diameters of the plurality of concave portions (convex portions) is preferably 10 degrees or less, and 8 degrees More preferably, it is 6 degrees or less, more preferably 4 degrees or less, and most preferably 0 degrees.

  In this case, the light incident portion has a concave portion (convex portion) of other shapes / arrangements (for example, the opening portion (bottom surface) has an isotropic shape such as a circle, or the opening portion (bottom surface) has an anisotropic shape. May be present in a different orientation). However, the sum of the areas of the openings (bottom surfaces) of the concave portions (convex portions) having an anisotropic shape in which the opening portions (bottom surface) are long in one specific direction is the opening portion (bottom surface) of the other concave portions (convex portions). ) Is preferably larger than the total area.

  Generally, in the light guide member used in combination with the point light source, the direction in which light is desired to be diffused is often the long axis direction of the light exit surface or the long axis direction of the light incident portion. A direction perpendicular to the major axis direction of the light exit surface or the light incident portion is preferable. That is, the openings (bottom surfaces) of the plurality of concave portions (convex portions) preferably have an anisotropic shape that is long in the direction perpendicular to the long axis direction of the light exit surface or the light incident portion.

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.
Specific examples of the anisotropic shape include a straight line (groove) as shown in FIG. 1 and a substantially elliptical shape as shown in FIG.
The shape of the concave portion (convex portion) can be determined by observing an arbitrary portion of the light incident portion with a microscope (such as a scanning electron microscope or a laser confocal microscope).

There is no limitation on the pitch in the direction parallel to the long axis direction of the light exit surface / light entrance portion of the recess (projection).
Here, the pitch in the direction parallel to the light exit surface of the concave portion (convex portion) / the long axis direction of the light entrance portion is an arbitrary pitch parallel to the long axis direction of the light exit surface of the light entrance portion or the long axis direction of the light entrance portion. The horizontal distance (distance in a direction parallel to the light incident portion) between the adjacent valley bottoms (in the case of concave portions) or mountain peaks (in the case of convex portions) in the cross-section of Fig. 13 (see Fig. 13). If the valley bottom (mountain peak) is flat, the pitch is determined with the center as the valley bottom (peak peak).
The pitch in the direction parallel to the light exit surface of the recess (convex portion) / the long axis direction of the light entrance portion can be measured with a microscope using any cross section parallel to the long axis direction of the light exit surface of the light entrance portion or the long axis direction of the light entrance portion. It can be determined by observing and measuring with a scanning electron microscope or a laser confocal microscope.

There is no limitation on the size (depth / height) of each recess (projection). For example, the short diameter (in the case of an isotropic shape) 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.
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 portion. 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 Figure 13)
The size of the concave portion (convex portion) can be determined by observing and measuring an arbitrary portion of the light incident portion 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 (溝), the length is the light emitting surface of the point light source (in the case where the light guide member has the shape shown in FIG. 1, in the thickness direction of the light guide member). It is preferably larger than the length. 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 member. In FIG. 1, the groove has a length that traverses the light incident part in the thickness direction of the light guide member (from the light exit surface to the opposite surface), but the length of the groove (畝) is not necessarily included. It does not have to cross the optical part.

There is no particular limitation on the region where the concave portion or the convex portion on the light incident portion 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 member. That is, in the light guide member of the present invention, the light incident portion may have a portion (region) having no concave portion or convex portion. 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 parts of a light guide member, the area of the opening part (bottom surface) of a recessed part (convex part) is sufficient. The total preferably occupies 25% or more (more preferably 50% or more, and 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 24A to 24J. In FIGS. 2, 3 and 24, in order to simplify the description of the structure of the plurality of concave portions or the convex portions themselves, the fine uneven structure on the surface is omitted.
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 have anisotropic diffusion characteristics in which a diffusion angle in a direction perpendicular to the grooves (described later) is 60 degrees and a diffusion angle in a direction parallel to the grooves is 1 degree. . 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).

The average pitch in the direction perpendicular to the major axis direction of the light exit surface / light entrance portion of the plurality of concave portions or convex portions 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 member. 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 member of the present invention is visible light (an electromagnetic wave of 380 nm to 780 nm), the average pitch is a value as described above in order to sufficiently exhibit the diffusion effect by the concave portion or the convex portion. Preferably there is.
The average depth (height) of the concave portion or convex portion is preferably 500 nm to 50 μm, more preferably 700 nm to 30 μm, and further preferably 5 to 10 μm.
The average pitch in the direction perpendicular to the long axis direction of the light exit surface / light incident portion of the concave portion or the convex portion is arbitrary vertical parallel to the long axis direction of the light exit surface of the light incident portion or the long axis direction of the light entrance portion. Let it be the average value of the pitch of the recessed part (convex part) which exists in 100 micrometers extracted arbitrarily from the cross section. Further, the average depth (height) of the concave portion or the convex portion is an average value of the depth (height) of the concave portion (convex portion) existing at 100 μm arbitrarily extracted from an arbitrary vertical section of the light incident portion. .

Next, the fine concavo-convex structure (second concavo-convex structure) provided on the surface of the plurality of concave portions or convex portions will be described.
Here, the “fine concavo-convex structure” refers to concavo-convex whose average height is 1/10 or less of the average depth (height) of a plurality of concave portions (convex portions) (first concavo-convex portions).
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.

The fine uneven structure is preferably a moth-eye structure. Here, the “moth eye structure” refers to a concavo-convex structure in which convex portions having substantially the same shape with a height of 1 μm or less are provided approximately periodically. The height may be 50 to 500 nm or 100 to 300 nm.
In this case, the convex portions can be arranged in, for example, a square lattice shape, a rectangular lattice shape, a square quadrangular lattice shape, a triangular lattice shape (honeycomb), or a hexagonal lattice shape, and the pitch thereof is, for example, 50 to 500 nm. It is good also as 100-300 nm.
A specific example of the moth-eye structure and a specific example of a plurality of concave portions (diffusion characteristics: 33 ° isotropic diffusion) having a moth-eye structure on the surface are shown in FIGS. 16 and 17, respectively.

The fine uneven structure may be provided on at least a part of the surface of the plurality of recesses or protrusions (first unevenness), but provided on the entire surface of the plurality of recesses or protrusions (first unevenness). It is preferable that
The fine uneven structure may be provided in a region other than the plurality of concave portions or convex portions (first unevenness) of the light incident portion, and is preferably provided in the entire light incident portion.

  The fine concavo-convex structure may be formed of the same material as the plurality of concave portions or convex portions (first concavo-convex portions), or may be formed of a different material. In the case where a fine concavo-convex structure is formed of the same material as a plurality of concave portions or convex portions (first concavo-convex portions), it can be easily manufactured.

There is no limitation on the method of forming a plurality of concave portions or convex portions having a fine concavo-convex structure on the surface of the light incident portion of the light guide member of the present invention. As a result of various studies by the present inventors, the fine concavo-convex structure (second concavo-convex structure) has a slight pressure (the degree necessary to transfer the first concavo-convex structure) due to the fine structure. It was found that even if pressure was applied, it was not broken. Therefore, after manufacturing the light guide member which has a 2nd unevenness | corrugation in the surface of a light-incidence part previously, the 1st unevenness | corrugation can be formed on the surface by transfer.
Specifically, (1) a method of injection molding a light guide member using a mold having a concave and convex pattern corresponding to a plurality of concave portions or convex portions having a fine concave and convex structure on the surface, and (2) first and second A method of transferring irregularities on the light incident portion of the light guide member using two types of transfer molds having an irregular pattern corresponding to the two irregularities, and (3) a plurality of concave portions having a fine irregular structure on the surface or For example, a method of attaching a film having a convex portion to a light guide member using a light-transmitting adhesive or the like can be used.

  As a method of (1), for example, a plurality of concave portions having a fine uneven structure on the surface or a stamper having a concave / convex pattern corresponding to the convex portion is disposed at a position corresponding to a light incident portion of a mold for molding a light guide member. And the light guide member which has the some recessed part or convex part which has a fine uneven structure on the surface from the beginning can be injection-molded. This method is suitable for manufacturing a light guide member for a surface light source device and a light guide member for an in-vehicle illumination 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 member (raw sheet for light guide member production) having no uneven structure by extrusion molding or cast molding, a light incident portion (light incident portion and The second unevenness is transferred to the surface of the light incident part on which the second unevenness is formed using a transfer mold having an uneven pattern corresponding to the second unevenness on the surface of the light incident portion. The light guide member of the present invention can be manufactured by transferring the first unevenness using a transfer mold having an uneven pattern corresponding to the unevenness.
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 a light incident portion of the transparent substrate is heated while heating a transfer roller 42 a having an uneven pattern corresponding to the second unevenness on the surface 4 a. The second unevenness is transferred by pressing against the surface, and then the transfer roller 42b having an uneven pattern corresponding to the first unevenness (here, the groove structure) is heated on the surface 4b on which the second unevenness is formed. Then, the first unevenness is transferred by pressing against the surface to be the light incident part of the transparent substrate. According to this method, a plurality of light guide members can be collectively transferred, so that mass production is possible and quality is improved.

As described above, the second unevenness is very fine and is not easily broken. Therefore, even if a pressure necessary for transferring the first unevenness is applied to the whole, the second unevenness is not broken. However, when the temperature of the transfer roller 42b for transferring the first unevenness is very high and the material constituting the second unevenness is completely softened, the shape of the second unevenness is maintained. It is not possible. Therefore, it is preferable that the heating temperature of the transfer roller 42b when transferring the first unevenness is slightly lower than the heating temperature of the transfer roller 42a when transferring the second unevenness.
From the same point of view, the surface of the transparent substrate 41 that serves as the light incident portion is made of a material having a softening temperature higher than that of the material constituting the transparent substrate 41 main body for forming the second unevenness. It is also preferable to form in advance a layer having a thickness larger than the height of the first layer, and to form the second unevenness on the layer at a relatively high temperature, and then form the first unevenness at a lower temperature.

As a specific example of the method (3), a. A sealing mold, and b. There are two types of tape-type methods.
a. Seal type On the transparent base film made of polyethylene terephthalate, polycarbonate, polystyrene, etc., the method described in the above (2), or a concave / convex pattern corresponding to a plurality of concave portions or convex portions having a fine concave / convex structure on the surface A plurality of concave portions or convex portions having a fine concavo-convex structure is formed on the surface by using a transfer mold or the like. Specifically, for example, an ultraviolet curable resin layer is applied on a base film, and a plurality of concave or convex portions having a fine concavo-convex structure are formed on the surface of the ultraviolet curable resin layer using a transfer mold. . 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, the adhesive film is applied to the surface opposite to the surface on which the concavo-convex structure of the base film is formed, and a release film made of polyethylene terephthalate or the like is bonded thereto, or the adhesive film with the release film is attached. A multilayer film in which the pressure-sensitive adhesive side is covered with a release film is produced by bonding the pressure-sensitive adhesive layer together. 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, in order from the bottom, the release film 51, the adhesive layer 52, the base film 53, and a layer 54 in which a plurality of concave portions or convex portions (here, a plurality of grooves) having a fine uneven structure are formed on the surface. Are stacked. Further, in the multilayer film 5b, an adhesive layer and a backing film layer are further provided on the layer 54 on which the concavo-convex structure is formed, and the release film 51, the adhesive layer 52, the base film 53, and the concavo-convex structure are formed in this order from the bottom. The formed layer 54, the adhesive layer 55, and the 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 member, and the thickness thereof is not limited. For example (depending on the material), 20 to 20 It can be set to 100 μm. 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 adhesion layer 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 portion of the light guide member, and then in the case of the multilayer film 5a, only the release film 51 is left, and in the case of the multilayer film 5b, a backing film. 56 and the adhesive layer 55 are left, and the remaining layer is cut into the same width as the thickness of the light incident portion (half cut), thereby forming a fine uneven structure on the surface having the same size as the light incident portion of the light guide member. Manufactures a seal sheet in which a plurality of concave or convex films (concave / convex structure seals) having a plurality of films are formed on a release film 51 (in the case of the multilayer film 5a) or a backing film 56 (in the case of the multilayer film 5b). To do. 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 stick together again. There is an advantage that the problem of being difficult 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 prepared is shown in FIG. In FIG. 6, each vertical line indicates a groove 61.
And in the manufacturing process of a light guide member and the assembly process of various illuminating devices which have a light guide member, in the case of the multilayer film 5a, the film (unevenness | corrugation in which the several recessed part or convex part which has a fine uneven structure on the said surface was formed. The structural seal is peeled off from the release film 51 one by one and bonded to the light incident portion of the light guide member via the adhesive layer 52. In the case of the multilayer film 5b, the film (uneven structure seal) on which the uneven structure is formed is peeled off from the adhesive layer 55 one by one, and then the release film 51 is peeled off and bonded to the light incident part via the adhesive layer 52. Finally, if necessary, the air between the film and the light incident part may be brought into close contact by removing with a roller or the like.
Prior to bonding, surface adhesion such as excimer UV treatment and corona treatment is applied to the adhesive layer 52 and / or the light incident part to cut off the surface molecular bonds, and immediately the adhesive layer and the light incident part are brought into close contact with each other. By doing so, the bonding strength can also be improved. Furthermore, if such a surface treatment is used, it is possible to bond a base film of a film having a plurality of concave portions or convex portions having a fine uneven structure on the surface and a light guide member without using an adhesive. Thus, cost reduction and reliability improvement can be achieved.
According to this seal-type method, the bonding operation to the light incident portion is facilitated, and the number of used (bonded) seals can be easily managed, so that the light guide member can be easily manufactured. Furthermore, transportation of the light guide member 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 part of the light guide member, and when assembling the surface light source device or the lighting device, two or more sheets are used. A multilayer film (seal) may be bonded to the light incident part. At this time, each multilayer film (seal) covers the area 2 mm or more outside (up / down / left / right) from the area facing the light emitting surface of the light source of the light incident part (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 a plurality of concave portions or convex portions having a fine concavo-convex structure is formed on the surface is manufactured. Next, this is cut into a plurality of tapes by cutting into the same width as the thickness of the light incident part, and each is wound around 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.
And in the manufacturing process of the light guide member and the assembly process of the surface light source device and the illumination device having the light guide member, the roll 72 has a layer in which a plurality of concave portions or convex portions having a fine concavo-convex structure are formed on the surface. The tape (tape-shaped film) is fed out and cut to the length of the light incident portion of the light guide member and then bonded to the light incident portion, or is bonded to the light incident portion and then cut to the length of the light incident portion. For bonding, a. The same method as described in the seal-type method can be adopted.
According to this method, since the length for cutting the tape may be determined when the tape is bonded to the light guide member, one type of roll (a plurality of concave or convex portions having a fine concavo-convex structure formed on the surface is formed. The roll of the tape-like film having a layer) can be used for the production of light guide members having various sizes, 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 member.

As the pressure-sensitive adhesive used in the method (3), it is preferable to use a pressure-sensitive adhesive corresponding to the optical application. Specifically, it is preferable to select the type and thickness of the pressure-sensitive adhesive so that the total light transmittance of the pressure-sensitive adhesive layer is 90% or more and the haze is 1.0 or less.
Commercially available adhesives include CS9621, HJ9150W (manufactured by Nitto Denko), DH425A (manufactured by Sanei Kaken), ZACROS TR-1801A (manufactured by Fujimori Kogyo), PD-S1 (manufactured by Panac), MO-3006C, MO-3012C (manufactured by Lintec) ) Etc. can be used.
In addition, a multilayer film having a plurality of concave or convex portions having a fine concavo-convex structure on the surface is disposed in the vicinity of the light source when it is affixed to a light guide member and incorporated in a surface light source device or a lighting device. Therefore, it is preferable to use an adhesive that can withstand the influence of heat from the light source. The pressure-sensitive adhesive satisfying such conditions varies depending on the material of the base film. For example, when the film base material is polyethylene terephthalate and the light guide member is polymethyl methacrylate resin and used in an environment of 85 ° C., among the above-mentioned adhesives, ZACROS TR-1801A, PD-S1, MO-3006C is preferred. Further, the pressure-sensitive adhesive that can withstand high temperature environments of 100 ° C. is PD-S1 and ZACROS TR-1801A.
If the multilayer film having a plurality of concave or convex portions having a fine concavo-convex structure on the surface is not attached to the light incident part with an adhesive or the like and integrated with the light guide member, the effect of the present invention is It is not demonstrated. That is, the incident light inside the light guide member is simply disposed between the light incident portion of the light guide member and the light source by simply arranging a film having a plurality of concave or convex portions having a fine concavo-convex structure on the surface. Cannot be diffused over a wide angle (and luminance unevenness derived from hot spots and other point light sources cannot be eliminated).

  Further, in order to improve the optical performance, the layer having a plurality of concave portions or convex portions having a fine concavo-convex structure on the surface in the method of (3) is mixed with, for example, silicon fine particles having an average particle diameter of about 2 μm, and the internal diffusion performance. Is also useful. In the embodiment, a layer made of an ultraviolet curable resin that does not have such silicon fine particles is used.

  A plurality of recesses having a fine concavo-convex structure on the surface of the mold (stamper), transfer mold (transfer roller) used in the methods (1) and (2) and the film used in the method (3), etc. Alternatively, there is no limitation on the method of forming the concave / convex pattern corresponding to the convex part, and for example, it may be formed by machining such as cutting or sandblasting, may be formed by nanoimprint technology, or laser speckle pattern exposure. Can also be formed. 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. Particularly suitable for the formation of Moreover, as a concavo-convex pattern corresponding to the second concavo-convex pattern, a commercially available moth-eye master (prototype) may be used.

Specifically, when speckle pattern exposure is used, a random uneven structure can be formed as follows.
For example, a speckle pattern having a random spot pattern or stripe 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, random irregularities corresponding to the speckle pattern are formed on the photosensitive material.
Note that the random speckle pattern or striped speckle pattern can be generated, for example, by diffusing laser light with a diffusion member having strong anisotropy. Normally, when the laser beam is diffused with a diffusing member and irradiated onto the exposure surface, speckles are generated as circular irregularities. However, if the diffusing member 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 transfer mold used in the method (2) is further known to those skilled in the art such as electroforming using the sub-master mold as the exposed photosensitive material having the concavo-convex structure produced as described above. It can be produced by depositing a metal by the method described above, transferring a concavo-convex pattern corresponding to the concavo-convex structure to the metal, peeling it from the sub-master mold, and optionally processing it into a roll.
Also, a mold used in the method (1) and a transfer mold used in the production of the tape / film in the method (3) (having a concavo-convex pattern corresponding to a plurality of concave or convex portions having a fine concavo-convex structure on the surface. In the case of a mold / transfer mold), the transfer mold prepared as described above and the second uneven transfer mold prepared separately by nanoimprint or the like are used, and the method described in (2) above. A plurality of concave portions or convex portions having a fine concavo-convex structure on the surface thereof is formed on the thermoplastic resin layer or the like, and then a metal master can be manufactured in the same manner as described above using this as a sub master type.

  In addition, a method for producing a fine concavo-convex pattern using a speckle pattern by interference exposure is well known, and is disclosed in, for example, Japanese Patent No. 3341519, Japanese translations of PCT publication No. 2003-525472 and Japanese translations of PCT publication No. 2004-508585. Yes.

The shape (outer shape) of the light guide member of the present invention is not particularly limited as long as it has a light exit surface and a light incident portion, and the positional relationship between the light exit surface and the light incident portion. Further, it is sufficient that there is at least one light incident portion, and there may be two or more.
Although there is no limitation on the thickness of the light guide member (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.

When the light guide member of the present invention is used for a surface light source device or a vehicle interior light, the light incident part is preferably located beside the light exit surface (a surface intersecting with the light exit surface). Specifically, the light guide member has a flat plate shape having a light exit surface and a facing surface opposite to the light exit surface as illustrated in FIG. 1, and the light incident portion includes the light exit surface and the facing surface. It is preferable that it is located in the side surface pinched | interposed between.
In this case, when the light guide member has two light incident portions, the shape of the light guide member is preferably a flat rectangular parallelepiped having a light exit surface and a facing surface as main surfaces, and further, two light incident portions. Are preferably facing each other. In this case, since two opposing light incident portions have the same length, there is an advantage that the number and types of point light sources can be made the same and parts can be shared.

  When used for a vehicle signal lamp, the light incident part is preferably located at a position facing the light exit surface. Specifically, the light guide member has a curved plate shape with the light exit surface 282 convex as shown in the schematic cross-sectional view of FIG. 28, and the light incident portion 281 faces the light exit surface. Located on the side of the surface 283 (particularly, on the side surface or the bottom surface of the groove provided on the opposing surface 283 and perpendicular to the major axis direction of the opposing surface and having a V-shaped or U-shaped cross section) It is preferable.

The material of the light guide member 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. It is possible to use a highly transparent polymer material or an inorganic material such as glass.
In addition, the light guide member of the present invention includes organic and inorganic dyes and pigments, matting agents, heat stabilizers, flame retardants, antistatic agents, antifoaming agents, color stabilizers, antioxidants, ultraviolet rays as necessary. Additives such as an absorbent, an impurity scavenger, a thickener, a surface conditioner, and a release agent may be contained within a range that does not impair the object of the present invention.

When the 1st unevenness | corrugation (plural recessed part or convex part) in the light guide member of this invention has an anisotropic shape where the opening part (bottom surface) of a several recessed part (convex part) is long in one specific direction 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 diffusion in the direction parallel to the specific one direction is performed. It exhibits anisotropic diffusion characteristics with a minimum angle, and it is not dominant whether or not the surface has a fine uneven structure (second unevenness). There is no limitation on the specific value of the diffusion angle (the diffusion angle (FWHM) of the emitted light when a light beam is incident perpendicularly to the light incident portion), but the diffusion angle in the direction parallel to the major axis direction of the light exit surface Or it is preferable that the diffusion angle to the direction parallel to the major axis direction of a light-incidence part is 30 degrees-120 degrees, More preferably, they are 40 degrees-100 degrees, More preferably, they are 50-90 degrees. On the other hand, the diffusion angle in the direction perpendicular to the major axis direction of the light exit surface or the diffusion angle in the direction perpendicular to the major axis direction of the light incident portion is preferably 20 ° or less.
The diffusion angle of the light exit surface / light entrance portion in the direction perpendicular to and parallel to the major axis direction is the shape, depth and height of each concave portion (convex portion) constituting the first concave-convex structure. It can be adjusted by appropriately changing the pitch or the like, and when the first concavo-convex structure is formed using a speckle pattern, these can be adjusted by appropriately changing the conditions for diffusing the laser beam.
Further, it is preferable that the diffusion characteristic is substantially constant in the entire region where the first unevenness of the light incident portion 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. Angular distribution of transmitted light intensity of light incident on the unevenness from the normal direction of the surface on which the first unevenness is formed, using a variable angle color difference meter such as manufactured by Photon or GC5000L manufactured by Nippon Denshoku Industries Co., Ltd. It can be determined by measuring (the distribution of the intensity of transmitted light with respect to the emission angle). Here, the normal direction of the surface on which the first unevenness is formed refers to the direction indicated by 16 in FIG.

  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 said (3) is employ | adopted as a method of forming the recessed part or convex part which has a fine uneven structure on the surface in the light-incidence part of a light guide member, it has a fine uneven structure on the surface. Even if the diffusion angle is measured with a film having a concave portion or a convex portion alone, or the diffusion angle is measured in the final state in which the film is bonded to the light guide member, 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 part may be produced, and the diffusion angle thereof may be measured. In addition, when the surface facing the surface (light incident part) on which the first concavo-convex structure to be measured is not smooth, the facing surface is made smooth by cutting the surface or the like, or Can be measured by transferring the surface shape of the surface to be measured to a material having the same refractive index as the material forming the surface, and using it (even if the unevenness is reversed, the angular distribution of transmitted light intensity Does not change, so the diffusion angle does not change).

Further, when a light ray is incident on the first unevenness of the light incident portion from the normal direction, the transmitted light intensity of the light is 90% or more of the peak intensity at the emission angle = 0 °. It is preferable to become.
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 °.
In this way, the surface shape of the region where the first unevenness of the light incident portion is formed is such that the angular distribution of the transmitted light intensity of light when a light ray is incident from the normal direction does not have a plurality of peaks, It is preferable that it changes gently.

It is presumed that the anisotropic diffusion characteristic derived from the anisotropy of the first uneven shape as described above also contributes to wide-angle diffusion of incident light (reduction in luminance unevenness such as hot spots).
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 one direction cannot be maximized. When such a member with low anisotropy accuracy is provided in the light incident portion, the light guide efficiency is deteriorated. Furthermore, light leakage immediately after entering the light guide member becomes severe due to insufficient anisotropy, and quality suitable for a display device or a lighting device cannot be obtained. In addition, in the technique disclosed in Patent Document 5, anisotropy is provided by utilizing refraction between the pressure-sensitive adhesive and the filler. The diffusion angle cannot be set to a sufficiently large value.
On the other hand, when the anisotropic diffusion characteristic is realized by the shape of the first unevenness, the highly accurate anisotropic diffusion characteristic can be stably obtained by controlling the surface shape. . Furthermore, in this case, the refraction resulting in anisotropic diffusion is between the air (refractive index approximately 1) and the material (resin or resin composition) constituting the irregularities (refractive index approximately 1.3 to 1.6). Therefore, as compared with the technique disclosed in Patent Document 5 that utilizes refraction between the adhesive and the filler, the direction of the opening (bottom) of the recess (projection) in the direction perpendicular to the major axis direction The diffusion angle can be a large value.

The light guide member of the present invention has a surface facing the light exit surface (opposite surface) in a direction away from the light incident portion (or a position facing the light incident portion) in order to make the light distribution on the light exit surface uniform. A light scattering pattern having a gradation that becomes denser toward the surface can be formed. 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 pattern in the central portion of the opposing surface may be made higher.
As the light scattering pattern, for example, a portion in which a reflective or diffusive material is laminated (printed) on the opposite surface or a portion in which a concavo-convex shape is formed (hereinafter collectively referred to as “dot”) is separated from the light incident portion. Gradation pattern that gradually increases in area (in the case of printing, it may be a gradation pattern that gradually becomes darker), and the pitch becomes narrower as the same size of dots and uneven shapes are moved away from the light source. Gradation pattern. In this case, examples of the dot shape include a circle and a rectangle. The size of the dot can be set to about 0.1 to 2.0 mm, for example.

The light guide member having a concavo-convex structure in the light incident part as in the present invention has a slightly different degree of light arrival in a direction perpendicular to the light incident part (light propagation direction) than that in which the light incident part is smooth. . That is, the degree of light arrival in the direction horizontal to the light incident part is higher than that of the light guide member having a smooth surface, whereas the degree of light arrival in the direction perpendicular to the light incident part is incident light. The portion tends to be lower than that of a light guide member having a smooth surface. Accordingly, the light scattering pattern of the portion close to (directly facing) the light incident portion on the opposing surface is more difficult to scatter than the light scattering pattern on the opposing surface of the light guide member whose light incident portion is a smooth surface (for example, dots It is preferable to make the area smaller) or to make the density 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 light scattering pattern having gradation (for example, the area is 0% or more when changing the dot area) It can be changed only to a range of 100% or less.
In the light guide member of the present invention, it is preferable that the luminance at each position on the light exit surface is in a range of 50% or more and 150% or less as compared with a value when the light incident part is smooth. More preferably, they are 60% or more and 140% or less, More preferably, they are 70% or more and 130% or less.
If the luminance at each position on the light exit surface is within the above range compared to the value when the light incident part is smooth, the light scattering pattern of the above surface can be changed by redesigning the light scattering pattern on the opposite surface. The reach can be controlled within a preferable range.
In the case where the light guide member of the present invention is included in the surface light source device, when the light scattering pattern as described above is provided on the facing surface, in order to further reduce the luminance unevenness, as shown in FIG. In the vicinity and the position facing the point light source, it is preferable not to form dots, or to reduce the density of dots 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.

  When the light guide member of the present invention is for a surface light source device for a display device, a plurality of random grooves perpendicular to the light incident surface may be provided on the light exit surface and / or the opposite 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 member can be 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 the light guide member 91 of the present invention and a plurality of point light sources 92 disposed in the vicinity of the light incident portion of the light guide member.
As described above, the light guide member has a flat plate shape in which the main surface is the light output surface and the opposite surface opposite to the light output member, as illustrated in FIG. 1, and the light incident portion faces the light output surface. What is in the side surface pinched | interposed between the surfaces is preferable.
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 part of the light guide member 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 member and the light emitting surface is increased, the amount of light incident on the light guide member 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 part of the light guide member of the present invention is preferably short. On the other hand, since heat is generated around the point light source and the light guide member 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 equally spaced along the light incident part of the light guide member (parallel to the light exit surface) on a straight line (the “equal distance” includes an error of ± 10%). It is preferable to arrange. 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, since the light guide member of the present invention in which luminance unevenness in the vicinity of the light incident portion on the light exit surface is reduced is used as the light guide member, the arrangement pitch of the point light sources is somewhat large. However, it is possible to realize a light emitting surface without a hot spot. Specifically, for example, when used for a display device, it is about 20 mm to 50 mm, 30 mm to 50 mm, or 40 mm to 50 mm, and when used for a vehicle interior light or the like, 80 mm to 200 mm, 100 mm. If it is about -200 mm or about 120 mm-200 mm, luminance unevenness can be suppressed within an allowable range.

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

Next, the display device of the present invention will be described.
The display device of the present invention includes a display panel having a display area for displaying by adjusting light transmission of the surface light source device, and the above-described surface light source device disposed on the back surface of the display panel.

The display area (active area) of the display panel is designed to start from the inside of the light incident part of the light guide member, because uneven luminance occurs near the light incident part of the light guide member and sufficient display quality cannot be guaranteed. It is preferable.
That is, the horizontal distance G between the light incident portion 93 of the light guide member 91 and the display area (the region 94 when the region 94 corresponding to the display area is projected on the light guide member 91 and the light incident portion 93 It is preferable that the distance (see FIG. 9) is designed to ensure a certain level or more.

However, in the light guide member of the present invention used in the display device of the present invention, the luminance unevenness in the vicinity of the light incident portion is reduced, so that it is necessary to form the display area on the inner side as the conventional light guide member is used. No (no need to increase G).
Specifically, in the display device of the present invention, the horizontal distance G between the light incident portion of the light guide member and the display area is set to G <P (P / G>) with respect to the arrangement pitch P of the point light sources. 1), and further G <P / 2 (P / G> 2).
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.
In addition, as shown in the Example mentioned later, even if the arrangement pitch P of a point light source is changed, even if the horizontal distance G between the light-incidence part of a light guide member and a display area is changed, P / G Are the same value, the same luminance unevenness reduction performance is exhibited.

When the light guide member of the present invention has two light incident parts, the arrangement pitch of the point light sources arranged in the vicinity of the first light incident part is P1, and the point light source arranged in the vicinity of the second light incident part When the arrangement pitch is P2, the horizontal distance between the first light incident part and the display area is G1, and the horizontal distance between the second light incident part 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 more preferable.
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 inside of the dotted line 111 is a display area 112, and a black matrix 113 for preventing light leakage is provided outside the display area 112, and panel wiring (not shown) and the like exist on the back side thereof. 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.

  Further, the display device 121 of the present invention is combined with a front cabinet 122 provided with speakers 1221; various circuit boards such as a television tuner circuit board 123, a power circuit board 124, a control circuit board 125; a back cabinet 126, a stand 127, and the like. Thus, a television receiver can be manufactured. FIG. 12 shows an example of the configuration of such a television receiver 12.

Next, the case where the light guide member of the present invention is applied to an in-vehicle illumination device (vehicle signal lamp) will be described.
FIG. 29 shows a cross-sectional view of a vehicle width lamp 29 which is an example of an in-vehicle lighting device (vehicle signal lamp).
29 includes a light guide member 28 having light incident portions 281a and 281b and a light exit surface 282, and a point light source 291a disposed in the vicinity of the light incident portion (so as to face the light incident portion). , 291b, which are housed in a lamp chamber space comprising a front lens 292 and a lamp body 293.
As described above, it is preferable that the light guide member has a curved plate shape with the light exit surface convex, and the light incident portion is located on the facing surface facing the light exit surface. A groove having a V-shaped or U-shaped cross section (including an inverted trapezoidal shape) perpendicular to the major axis direction is formed on the surface, and a light incident part is a side surface (one or both) of the V-shaped groove. Or the side surface (one or both side surfaces) and / or the bottom surface of the U-shaped groove.

Although there is no limitation in a point light source, it is preferable to use LED (light emitting diode) similarly to a surface light source device. There is no limitation on the type of LED, and white LED, red LED, yellow LED and the like exemplified in the description of the surface light source device can be used. There is no limitation on the outer shape of the LED and the size of the light emitting surface, and the same LED that can be used in the surface light source device can be used. The distance between the point light source and the light incident part of the light guide member can be set to the same level as that of the surface light source device.
Since the light guide member of the present invention is capable of wide-angle diffusion of incident light, the entire light exit surface can emit light even when the number of point light sources is small. Therefore, it is not necessary to arrange many point light sources, and at least one point light source is sufficient.
Also, the in-vehicle illumination device can further include various optical elements as in the surface light source device.

  Subsequently, examples of the present invention will be described. The following examples and comparative examples are examples in the case where the light guide member of the present invention is applied to a surface light source device. The light guide member to be used is a light exit surface and a light exit surface as shown in FIG. And a light incident surface (light incident portion) sandwiched between the light exit surface and the opposite surface.

[Standard Reference A]
The arrangement pitch P of the LEDs is 10.5 mm, and the horizontal distance G between the light incident surface (light incident portion) of the light guide member (material: polymethyl methacrylate, thickness: 4 mm) and the display area is 16.5 mm (P / G = 0.64) From a commercially available LED TV (BRAVIA KDL-32EX700 manufactured by Sony Corporation), only the surface light source device part is taken out, and the arrangement pitch of the LEDs becomes about 42 mm (P / G = 2.55). The LEDs are rearranged as described above, and the position 16.5 mm from the light incident surface side end of the light exit surface of the light guide member (corresponding to the display area start portion) and further 10 mm from the position (26 from the light incident surface side end). The luminance at 5 mm inside was measured using a two-dimensional color luminance meter (CA-2000) manufactured by Konica Minolta. The light incident part of the light guide member was a mirror surface.

[Example A]
In the above surface light source device, a polyethylene terephthalate film (PET film) having an average thickness of 125 μm having an ultraviolet curable resin layer having a plurality of grooves having a fine concavo-convex structure on the light incident surface of the light guide member. Was pasted using a transparent double-sided adhesive sheet (CS9621T manufactured by Nitto Denko Corporation), and the luminance at a position 26.5 mm inside from the light incident surface side end of the light exit surface was measured. 18 and 19 show photographs of a plurality of grooves having a fine concavo-convex structure on the surface employed in this example.
The shape of the plurality of grooves is produced by speckle pattern exposure, and the average pitch is about 10 μm and the average depth is about 5 μm.
Further, the fine concavo-convex structure formed on the surface of the plurality of grooves is the moth-eye structure shown in FIG. 20 manufactured by nanoimprinting, in which bell-shaped convex portions having a height of 300 nm are arranged in a honeycomb shape at a pitch of 250 nm. It is. The reflection reduction effect of this moth-eye structure is shown in FIGS. FIG. 21 shows the reflectance when light having a wavelength of 380 nm to 780 nm is incident on a triacetyl cellulose (TAC) film having a mirror surface as a control at an incident angle of 8 °. FIG. 22 shows the reflectance on the surface of the TAC film. It is a reflectance at the time of forming the moth-eye structure shown in FIG. When comparing FIGS. 21 and 22, it can be confirmed that the reflectance is reduced by a little less than 4% when the moth-eye structure shown in FIG. 20 is formed.
The UV curable resin layer having a plurality of grooves having a moth-eye structure on the surface uses a mold having a plurality of grooves prepared by the above speckle pattern exposure and a mold having a moth-eye structure prepared by nanoimprinting. First, a plurality of grooves having a moth-eye structure is formed on the surface of a thermoplastic resin, a roll-shaped metal transfer mold is produced using this as a submaster, and the pattern is pressed against an ultraviolet curable resin layer applied on a PET film, It was produced by irradiating ultraviolet rays from the side of the PET film to cure the ultraviolet curable resin layer.

[Comparative Examples A1 to A3]
In the surface light source device, the light guide member 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. In addition, each of the light guide members is a double-sided adhesive sheet on the light incident surface of the light guide member of the standard reference with a polyethylene terephthalate film having an average thickness of 125 μm and having a predetermined fine structure as in the light guide member of the example. It was manufactured by sticking using
Comparative Example A1: Light guiding member in which prisms with 90 ° apex angle (pitch: about 50 μm) having no fine uneven structure on the surface are periodically formed on the light incident surface Comparative Example A2: Surface on the light incident surface A light guide member in which lenticular lenses (pitch: about 120 μm) having no fine uneven structure are periodically formed Comparative Example A3: The apex angle R having no fine uneven structure on the light incident surface A light guide member in which prisms (pitch: about 50 μm) are periodically formed.

FIG. 26 shows variations in luminance of the surface light source device using the light guide members of Example A, Comparative Examples A1 to A3 and Standard Reference A. In FIG. 26, the vertical axis represents 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 represents the position in the width direction of the light incident surface of the light guide member.
In the surface light source device of Example A using the light guide member of the present invention, the luminance was almost constant regardless of the location, and no hot spot appeared. On the other hand, when a light guide member (standard reference A) used in a commercial television or a light guide member (Comparative Examples A1 to A3) corresponding to the light guide member disclosed in the prior art document is used. In this case, the brightness was not constant, a hot spot (maximum part) appeared, and the brightness unevenness could not be solved.

[Standard Reference B]
Take out only the surface light source device part from a commercially available LED TV (BRAVIA KDL-32EX710 manufactured by Sony Corporation) and measure the average in-plane brightness of the light exit surface without changing the LED arrangement. CA-2000).

[Example B]
The same polyethylene terephthalate film as used in Example A (a film having a plurality of grooves having fine concavo-convex structures formed on the light incident surface of the light guide member of the surface light source device described above is used in the example. Attaching was conducted in the same manner as in A, and the in-plane average brightness of the light exit surface was measured.

[Comparative Example B]
Implemented except that the tape to be affixed to the light incident surface of the light guide member was replaced with a polyethylene terephthalate film in which only a plurality of grooves were formed (a plurality of grooves having no fine uneven structure on the surface). In the same manner as in Example B, the in-plane average luminance of the light exit surface was measured.
[Reference Example B]
In-plane average brightness of the light exit surface was measured in the same manner as in Example B, except that the tape attached to the light incident surface of the light guide member was replaced with a polyethylene terephthalate film having only a fine concavo-convex structure (moth eye structure). did.

Table 2 shows values (luminance efficiency) obtained by dividing the in-plane average luminance by the input power in order to correct variations in the in-plane average luminance and input power of the standard reference B, the example B, the comparative example B, and the reference example B. .
The comparison is shown in FIG. In FIG. 23, the vertical axis represents the ratio of the in-plane average luminance of each sample when the in-plane average luminance of the standard reference B is 100%.

In Example B, it is higher than Standard Reference B (mirror surface) and Comparative Example B (only the first unevenness, without moth-eye structure) in which only a plurality of recesses or protrusions (first unevenness) are formed. In-plane average brightness was obtained. This in-plane average luminance corresponds to Reference Example B (only the second unevenness (moth eye structure)) in which only the moth-eye structure (second unevenness) was formed on the light incident surface.
From the above, the reflection reduction effect by providing a fine uneven structure on the surface of the light incident part is not only when the surface is flat, but also when the surface has undulations (unevenness). It was confirmed that it was obtained.

Since the light guide member of the present invention can diffuse light from a point light source in a wide angle, luminance unevenness (hot spot) in the vicinity of a light incident part when light is incident from the side surface side of the light exit surface using a plurality of point light sources. ) Can be eliminated. Therefore, it can be suitably used for a vehicle interior light (for example, white) using a point light source such as an LED or an edge light type surface light source device, particularly a surface light source device for a thin liquid crystal display device.
Further, the light guide member of the present invention can diffuse the light from the point light source over a wide angle, so that the light from a small number of point light sources can be emitted from a wide range. Therefore, it is necessary to ensure a light emission area of a predetermined value or more according to laws and regulations, for example, an indicator light for illuminating a meter panel or the like (eg, white); a brake light (eg, red), a vehicle behind or ahead It can be suitably used for a width lamp (eg, red, white), a direction indicator lamp (eg, yellow), and the like.

DESCRIPTION OF SYMBOLS 1 Light guide member 11 Light exit surface 12 Light entrance part 13 Groove 14 Thickness direction 15 of a light guide member Direction parallel to the long-axis direction of the light exit surface of a light entrance part 16 Normal direction 41 of light entrance part Transparent substrate 4a Transparent substrate Surface 4b Surface 42a on which second irregularities are formed Transfer roller 42b Transfer roller 5a Multilayer film 5b having a layer on which a groove structure is formed Multilayer film 51 having a layer on which a groove structure is formed 51 Release film 52 Adhesive layer 53 Base Film 54 Layer 55 in which groove structure is formed Adhesive layer 56 Mount film 61 Groove 71 Multilayer film 72 having a layer in which groove structure is formed Roll 9 Surface light source device 91 Light guide member 92 Point light source 93 Light incident portion 94 In the display area Corresponding 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 28 Light guide member 281a Light incident portion 281b Light incident portion 282 Light exit surface 283 Light guide surface 29 In-vehicle illumination device 291a Point light source 291b Point light source 292 Front lens 293 Lamp body G Light incident portion and display area of light guide member Horizontal distance P between the point light source array pitch

Claims (20)

A light guide member having a light exit surface and at least one light incident portion,
The light guide member, wherein the at least one light incident portion has a plurality of concave portions or convex portions having a fine concavo-convex structure on a surface thereof.   The light guide member according to claim 1, wherein the fine uneven structure is a moth-eye structure.   At least one of the shape, depth or height of the plurality of concave portions or convex portions, the pitch in the direction parallel to the major axis direction of the light exit surface, and the pitch in the direction parallel to the major axis direction of the light incident portion is irregular. The light guide member according to claim 1, which is different from each other.   The light guide member according to any one of claims 1 to 3, wherein openings or bottom surfaces of the plurality of concave portions or convex portions have an anisotropic shape that is long in a specific direction.   5. The light guide member according to claim 4, wherein the specific direction is a direction perpendicular to a major axis direction of the light exit surface or a direction perpendicular to a major axis direction of the light incident portion.   The average pitch in the direction parallel to the major axis direction of the light exit surface of the plurality of concave portions or convex portions or the average pitch in the direction parallel to the major axis direction of the light incident portion is 20 μm or less. The light guide member according to claim 1.   The light guide member according to any one of claims 1 to 6, wherein an average depth or height of the plurality of concave portions or convex portions is 1 to 50 µm.   The light guide member according to claim 1, wherein the concave portion is a groove.   The light guide member according to any one of claims 1 to 8, wherein an average pitch of the fine uneven structure / moth eye structure is 500 nm or less.   The diffusion angle in the direction parallel to the major axis direction of the light exit surface or the diffusion angle in the direction parallel to the major axis direction of the light incident part when a light beam is incident on the light incident part from the normal direction is 30 °. The light guide member according to claim 1, wherein the light guide member is at least 120 °.   In the distribution with respect to the emission angle of the transmitted light intensity when a light beam is incident on the light incident portion from the normal direction, the transmitted light intensity at an emission angle = 0 ° is 90% or more of the peak intensity. The light guide member according to any one of 10.   The light guide member according to any one of claims 1 to 11, wherein the plurality of concave portions or convex portions are formed by speckle pattern exposure. Having a flat plate shape with the light-emitting surface and a facing surface facing the light-emitting surface as main surfaces;
The at least one light incident portion is on a side surface sandwiched between the light exit surface and the facing surface;
The light guide member according to claim 1. The light guide member according to claim 13;
A plurality of point light sources disposed in the vicinity of the at least one light incident portion of the light guide member;
A surface light source device. A display panel having a display area for displaying light by adjusting light transmission;
The surface light source device according to claim 14 disposed on the back surface of the display panel;
A display device. The plurality of point light sources are arranged at equal intervals, and the arrangement pitch P and the horizontal distance G between the at least one light incident portion and the display area satisfy the following condition (1): The display device described.
(1) P / G> 1 The light guide member has two light incident portions sandwiched between the light exit surface and the facing surface;
The plurality of point light sources are arranged at equal intervals in the vicinity of each of the two light incident portions,
The arrangement pitch of the point light sources arranged in the vicinity of the first light incident section is P1, the arrangement pitch of the point light sources arranged in the vicinity of the second light incident section is P2, and the first light incident section and the display The following condition (2) is satisfied, where G1 is a horizontal distance between the areas and G2 is a horizontal distance between the second light incident portion and the display area. Display device.
(2) P1 / G1: P2 / G2 = 100: 90 to 100: 110 The display device according to claim 17, further satisfying the following condition (3):
(3) G1 ≠ G2   The display device according to claim 15, wherein the display panel is a liquid crystal display panel. A display device according to any one of claims 15 to 18,
A tuner for receiving broadcast video signals;
A television receiver.