Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0033—Means for improving the coupling-out of light from the light guide
  • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
  • G02B6/0036—2-D arrangement of prisms, protrusions, indentations or roughened surfaces
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
  • G02B5/021—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
  • G02B5/0221—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures the surface having an irregular structure
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
  • G02B5/021—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
  • G02B5/0226—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures having particles on the surface
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
  • G02B5/021—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures
  • G02B5/0231—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place at the element's surface, e.g. by means of surface roughening or microprismatic structures the surface having microprismatic or micropyramidal shape
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
  • G02B5/0236—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element
  • G02B5/0242—Diffusing elements; Afocal elements characterised by the diffusing properties the diffusion taking place within the volume of the element by means of dispersed particles
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
  • G02B5/0257—Diffusing elements; Afocal elements characterised by the diffusing properties creating an anisotropic diffusion characteristic, i.e. distributing output differently in two perpendicular axes
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B5/00—Optical elements other than lenses
  • G02B5/02—Diffusing elements; Afocal elements
  • G02B5/0273—Diffusing elements; Afocal elements characterized by the use
  • G02B5/0278—Diffusing elements; Afocal elements characterized by the use used in transmission
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
  • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
  • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
  • G02B6/0033—Means for improving the coupling-out of light from the light guide
  • G02B6/0035—Means for improving the coupling-out of light from the light guide provided on the surface of the light guide or in the bulk of it
  • G02B6/0038—Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• • G—PHYSICS
  • G02—OPTICS
  • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
  • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
  • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
  • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
  • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
  • G02F1/1333—Constructional arrangements; Manufacturing methods
  • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
  • G02F1/133524—Light-guides, e.g. fibre-optic bundles, louvered or jalousie light-guides

Definitions

• the present invention relates to a surface light source that irradiates a liquid crystal display element or the like from the back, and a liquid crystal display device that includes the surface light source.
• the surface light source there are a direct type in which a plurality of light sources are arranged directly under a liquid crystal display element, and an edge light type in which a light source is arranged so as to face a side end surface of a light guide.
• the direct type is mainly used for TV, and the edge light type has the advantage of being more compact than the direct type, in addition to car navigation systems, monitors, and small TVs.
• Patent Document 2 discloses a light guide in which a plurality of light diffusion patterns arranged substantially concentrically around a light incident surface is formed on a surface opposite to a light exit surface of the light guide. The surface light source used is disclosed.
• Patent Document 3 arc-shaped grooves or protrusions are formed on the surface opposite to the light exit surface at intervals from the light incident surface side, and concentrically on the exit surface side.
• a prism sheet in which prisms are arranged concentrically around the light incident surface side is combined on the light guide body on which a anisotropic holographic pattern is formed, with the prism surface facing the light incident surface side of the light guide body.
• a surface light source is disclosed.
• Patent Document 4 discloses a surface light source using a combination of a light guide and a diffusion sheet in which triangular prisms are arranged in a direction perpendicular to the light incident surface on the light exit surface of the light guide.
• Patent Document 5 a light guide having a prism array formed perpendicular to the light incident surface on the surface opposite to the light exit surface of the light guide is perpendicular to the prism array of the light guide.
• a prism sheet in which a prism is formed and combined with the prism surface facing the light incident surface side of the light guide is disclosed.
• Patent Document 1 Japanese Patent Laid-Open No. 1107406 (all pages)
• Patent Document 2 Patent No. 31351830 (all pages)
• Patent Document 3 Japanese Patent Application Laid-Open No. 2004-111383 (all pages)
• Patent Document 4 JP-A-8-179322 (all pages)
• Patent Document 5 JP-A-11 224516 (all pages)
• the diffusion pattern elements or the deflection pattern elements are arranged in a substantially concentric or concentric pattern. For this reason, there is a problem that it is difficult to increase the area of the surface light source. Also, it is difficult to control the viewing angle of the screen from the structural features of the pattern.
• An object of the present invention is to provide a sidelight type surface light source having excellent light utilization efficiency, high luminance and wide viewing angle, and a liquid crystal display device using the same, in view of the power and the background of the related art. There is to do.
• the inventors of the present invention have solved the above problems all at once by configuring the surface light source with a light guide having a specific structure and a film having anisotropic diffusivity.
• the inventors have found that a surface light source excellent in light utilization efficiency, viewing angle characteristics, and luminance uniformity can be provided, and the present invention has been completed. That is, the present invention is as follows.
• the surface light source of the present invention is a light source, a light guide having at least one light incident surface facing the light source, and a light emitting surface substantially orthogonal to the light source, and facing the light emitting surface.
• a light source having a plurality of linear shapes on the light exit surface or a light non-exit surface on the back surface of the light exit surface. Grooves or linear protrusions are provided substantially in parallel, and the first optical film has anisotropic diffusibility, and the direction in which the anisotropic diffusivity is maximum is the linear grooves or linear protrusions.
• the surface light source is arranged so as to be substantially parallel to the longitudinal direction of the light source.
• the surface light source of the present invention more preferably has any one of the following configurations (2) to (; 15). Become.
• the linear groove or the linear protrusion is at least one selected from the group consisting of a substantially arc shape, a substantially bell shape, a substantially triangular shape, and a substantially trapezoidal shape in cross section perpendicular to the longitudinal direction thereof.
• the first optical film has a half-value width Dlmax of transmitted light in a direction in which the diffusivity is maximized when a normal force or light is incident on the first optical film, and diffusion
• the surface light source according to any one of (1) to (5) above, wherein the ratio Dlmax / Dlmin to 3 or more of the half-value width Dlmin of transmitted light in the direction in which the property is minimum is 3 or more.
• the prism sheet has a length (light guide) direction substantially parallel to a direction in which diffusivity is maximized when light is incident on the first optical film from a normal direction.
• the second optical film is incident on the second optical film with a normal direction force or light.
• the ratio D2max / D2min between the half-value width D2max of the transmitted light in the direction where the diffusivity is maximum and the half-value width D2min of the transmitted light in the direction where the diffusivity is minimum is 5 or more,
• the liquid crystal display device of the present invention is equipped with the surface light source of the present invention.
• a light guide body in which a plurality of linear grooves or linear protrusions are provided substantially in parallel is used.
• the longitudinal direction of the linear groove or the linear protrusion and the direction in which the anisotropic diffusivity of the first optical film having anisotropic diffusivity is maximized are substantially parallel. Arrange them as follows. Thereby, light can be used efficiently. As a result, a high luminance surface light source can be obtained with the force S.
• FIG. 1 is an example of an exploded perspective view showing a relative positional relationship between members constituting a surface light source of the present invention.
• FIG. 2 is a diagram showing an example in which light sources are arranged on two or more side end faces of the light guide 3.
• FIG. 3 illustrates a preferred arrangement mode of the linear grooves 33 or the linear protrusions 34 when the light guide 3 in the surface light source of the present invention is observed from the light emitting surface 32 side. .
• FIG. 4 is a diagram of the light guide 3 in the surface light source of the present invention as viewed from the light exit surface 32 side. The preferred embodiment of the arrangement of the groove 33 or the linear protrusion 34 is illustrated.
• FIG. 5 is a diagram for explaining linear grooves or projections that are substantially parallel in the surface light source of the present invention.
• FIG. 6 illustrates a cross-sectional view perpendicular to the length direction of the linear groove 33 formed in the light guide 3 in the surface light source of the present invention.
• FIG. 7 illustrates a cross-sectional view perpendicular to the length direction of the linear protrusion 34 formed on the light guide 3 in the surface light source of the present invention.
• FIG. 8 is a diagram for explaining the definition of half width.
• FIG. 9 is a diagram for explaining an angle formed by the longitudinal direction of the linear groove 33 or the linear protrusion 34 and the direction in which the anisotropic diffusion property of the first optical film 5 is maximized.
• FIG. 10 is a perspective view showing a preferred form of the first optical film in the surface light source of the present invention.
• FIG. 11 is a perspective view showing a preferred form when the second optical film in the surface light source of the present invention is a prism sheet.
• FIG. 12 is a diagram for explaining an angle formed by the length direction of the prism and the direction in which the anisotropic diffusivity of the first optical film 5 is maximized.
• FIG. 13 is a perspective view showing a preferred embodiment when the second optical film in the surface light source of the present invention is an isotropic diffusion sheet.
• FIG. 14 is a schematic diagram for explaining light transmission characteristics of a prism sheet.
• FIG. 15 is a diagram schematically illustrating light that propagates through the light guide and exits.
• FIG. 16 is an example showing an emission angle distribution from the central portion of the light exit surface 32 of the light guide 3 when the surface light source of the present invention is in the form of FIG. 2 (a).
• FIG. 17 shows an emission angle from the central portion of the surface light source when the second optical film is installed on the light guide 3 when the surface light source of the present invention is in the form of FIG. 2 (a). It is an example showing the distribution.
• FIG. 18 is a schematic diagram showing measurement points of luminance of a surface light source in Examples and Comparative Examples.
• FIG. 19 schematically shows the form of the first optical film produced in Examples and Comparative Examples.
• FIG. 20 is a perspective view schematically showing the form of the first optical film produced in the examples and comparative examples.
• FIG. 21 is a perspective view schematically showing the form of the first optical film produced in Examples and Comparative Examples.
• FIG. 1 is an example of an exploded perspective view showing a relative positional relationship between members constituting the surface light source of the present invention.
• the surface light source of the present invention includes a light source 1, a reflector 2, a light guide 3, a reflection sheet 4, a first optical film 5, and a second optical film. And 6.
• the second optical film 7 is also a component of the surface light source. However, the second optical film 7 may not exist.
• the light source 1 is a linear light source extending in the y direction in FIG.
• the light source 1 for example, a fluorescent tube or a cold cathode tube can be used.
• the light source 1 one or a plurality of light emitting diodes (LEDs) arranged in parallel in the y direction in FIG.
• LEDs light emitting diodes
• the light source 1 is arranged on one side end surface of the light guide 3, that is, the light source 1 is
• FIG. 2 is a diagram showing an example in which light sources are arranged on two or more side end surfaces of the light guide 3.
• two light sources 1 and a reflector 2 are provided on the opposite end surfaces of the light guide 3 (two light incident surfaces 31), Fig. 2 (b), (c ), The light source 1 and the reflector 2 are provided on the adjacent side surface of the light guide 3 (two light incident surfaces 31 (FIG. 2 (c)), and three (FIG. 2 (b) ))) Is also preferably used as the surface light source of the present invention.
• the reflector 2 is disposed around the light source 1 and effectively makes the light from the light source 1 incident on the light guide.
• the characteristics required for the reflector 2 are preferably those having a high reflectance.
• the total light reflectance is preferably 85% or more. More preferably, it is 87% or more, particularly preferably 90% or more. If the total light reflectance of the reflector 2 is less than 85%, the light emitted from the light source 1 cannot be sufficiently reflected, and the screen brightness may be extremely inferior.
• a high-luminance surface light source can be obtained by setting the total light reflectance of the reflector 2 to 85% or more.
• the material of the reflector 2 is as follows: 1) a resin used as a main component and organic or inorganic dyes and fine particles added thereto; 2) a resin that is incompatible with the resin component; Alternatively, one or more materials selected from organic and inorganic particles are mixed and melt-extruded and then stretched in at least one direction to form fine bubbles inside. 3) Gas such as carbon dioxide gas is introduced into the molten resin. Injected and extruded, with bubbles inside, 4) Stacked multiple resin layers with different refractive indexes, 6) Deposited metal on at least one side of the reflective sheet of 1) to 4) , And combinations thereof, and any of them can be suitably used.
• thermoplastic resin with organic or inorganic fine particles added is laminated on at least one side of the film on which fine bubbles are formed by a method such as coextrusion, and further stretched to form finer bubbles in the surface layer portion than in the inner layer portion.
• the formed composite film can be particularly preferably used.
• the reflector 2 preferably contains a material that imparts light resistance, that is, a light stabilizer, in order to stably exhibit reflection characteristics over a long period of time. More preferably, the outermost surface layer preferably contains a light stabilizer.
• the outermost surface layer indicates a layer located on the most surface side when the reflector 2 has a laminated structure, and indicates the layer in the case of a single layer structure. In the case of a laminated structure, there are two outermost surface layers, but it is more preferable that at least the outermost surface layer on the light guide 3 side contains a light stabilizer.
• the material constituting the reflector 2 can be used in combination according to the application.
• metal is vapor-deposited on the back surface, or is attached to a colored film or metal foil such as black.
• a light shielding layer, a heat transfer layer, and a conductive layer are formed on the back side of the material constituting the reflector 2 by printing or vapor deposition.
• the light guide 3 has four side end surfaces. At least one side end surface is the light incident surface 31.
• the light source 1 faces the light incident surface 31 and is provided substantially parallel to the light incident surface 31. That is, the light guide 3 has two opposing side end faces that are substantially parallel to the xz plane and a termination face that is the side end face facing the light incident surface 31.
• the light guide 3 has two main surfaces. The two main surfaces face each other and are substantially orthogonal to the light incident surface 31. One of the two main surfaces is a light exit surface 32. A surface opposite to the light emitting surface 32 is a light non-emitting surface 35.
• the light exit surface 32 is disposed substantially parallel to the xy plane, and the projection onto the xy plane is substantially rectangular.
• the projection of the light guide 3 onto the xz plane may have a substantially wedge shape, in addition to a substantially rectangular shape, and a substantially wedge shape in which the film thickness decreases as the distance from the light source 1 increases.
• the light emitted from the light source 1 enters the light guide 3 from the light incident surface 31 of the light guide 3, propagates through the light guide 3, and is emitted from the light exit surface 32.
• the light guide 3 includes acrylic resins such as methyl methacrylate resin (PMMA), polycarbonate resins, polypropylene, polyisobutylene, polybutene. And a transparent resin material having a certain refractive index, such as a polyolefin resin such as polymethylpentene, a cycloolefin resin, or the like.
• PMMA methyl methacrylate resin
• polycarbonate resins polypropylene
• polyisobutylene polybutene
• a transparent resin material having a certain refractive index such as a polyolefin resin such as polymethylpentene, a cycloolefin resin, or the like.
• a plurality of linear grooves or linear protrusions are provided substantially in parallel on the light non-emitting surface 5 on the back surface of the light emitting surface 32 or the light emitting surface 35.
• a plurality of linear grooves 33 are provided substantially in parallel.
• a linear protrusion may be provided.
• channel and the linear protrusion may be mixed.
• the linear groove or the linear protrusion may be provided on either the light emitting surface 32 or the light non-emitting surface 35 or on both surfaces.
• FIG. 3 shows an arrangement of linear grooves 33 or linear protrusions 34 when the light guide 3 in the surface light source of the present invention is observed from the light emitting surface 32 side in the normal direction (z direction in FIG. 1).
• FIG. 3 shows an arrangement direction of the linear grooves 33 or the linear protrusions 34 of the light guide 3.
• the arrangement direction of the linear grooves 33 or the linear protrusions 34 is substantially perpendicular to the light incident surface 31 ( Fig. 3 (a)), almost parallel (Fig. 3 (b)), intermediate (Fig. 3 (c)), and combinations thereof (for example, Fig.
• the linear groove 33 or the linear protrusion 34 that is substantially parallel to the light incident surface 31 is preferably formed from the viewpoint that particularly high light utilization efficiency can be obtained. More preferably, the linear groove 33 or the linear protrusion 34 in the direction substantially parallel to the light incident surface 31 is formed denser than the linear groove 33 or the linear protrusion 34 in the other direction. Further, this array need not be formed uniformly in the entire surface of the light guide 3 and may be formed partially. Also, different arrays may be mixed in the same plane, or in a parallel relationship, or arrays may be mixed.
• the linear groove 33 or the linear protrusion 34 is formed continuously from one side surface of the light guide 3 to the other side surface. As long as the effect of the present invention is not lost, it is not necessary to be a straight line, but as shown in Fig. 4, it is bent, curved, or partially separated (Fig. The linear groove 33 or the linear protrusion 34 adjacent to each other may be partially out of parallel relation (not shown).
• substantially parallel means that adjacent linear grooves 33 or linear protrusions 34 as shown in FIG. This means that the angles ⁇ 41, ⁇ 42 (hereinafter referred to as ⁇ 4) formed by the extension lines in the longitudinal direction are within 0 ⁇ 15 °.
• 0 ° means that the extension lines in the longitudinal direction of adjacent linear grooves 33 or linear protrusions 34 do not intersect, that is, are parallel. More preferably, ⁇ 4 is within 0 ⁇ 10 °, and more preferably ⁇ 4 is within 0 ⁇ 5 °. As shown in FIG.
• the light incident on the light guide 3 is repeatedly totally reflected at the interface between the light guide 3 and the air while being incident on the light emitting surface 32 and the light non-emitting surface 35 at a critical angle or more. It propagates in the light body 3 and is not emitted outside the light guide body 3.
• the light colliding with the linear groove 33 or the linear protrusion 34 formed in the light guide 3 is guided by the linear groove 33 or the linear protrusion 34.
• the direction of travel is changed by reflection at the body 3 / air interface. As a result, the light is incident on the light emitting surface 3 2 at a critical angle or less, and is emitted to the outside of the light guide 3.
• in-plane emission characteristics can be controlled by appropriately controlling the shape and arrangement of the linear grooves 33 or the linear protrusions 34 formed in the light guide 3. As a result, it is possible to obtain a surface light source with high brightness and high brightness uniformity within the surface.
• the linear groove or the linear protrusion may be provided on either or both of the light emitting surface 32 and the light non-emitting surface 35. It is preferable that the linear grooves or the linear protrusions are provided on the light non-emitting surface 35 because particularly high light utilization efficiency is obtained and the control of the emission angle distribution is easy.
• the light exit surface 32 of the light guide 3 may be smooth or may be formed with various patterns. If the pattern is formed more than necessary on the light exit surface 32, it reaches the end surface facing the light entrance surface 31 away from the light source 1 (or up to the center when the light source 1 is installed on both sides). A lot of light is emitted from the light exit surface 32.
• the in-plane uniformity of brightness may be reduced, and the center brightness may be lowered.
• “smooth” means that the surface roughness Ra based on JIS-B0601 (2001 edition) is 50 nm or less.
• the surface roughness Ra is more preferably 30 nm or less, further preferably 20 ⁇ m or less, and most preferably lOnm or less.
• the surface light source of the present invention by setting Ra of the light emitting surface 32 of the light guide 3 to 50 nm or less, the surface light source having excellent luminance characteristics can be formed with a large area.
• FIG. 6 and FIG. 7 are drawings illustrating a cross-sectional view perpendicular to the length direction of the linear groove 33 or the linear protrusion 34 formed in the light guide 3 in the surface light source of the present invention (FIG. 1 X—z plane). 6 shows a cross-sectional view of the linear groove 33, and FIG.
• the preferred shape of the linear groove 33 of the light guide 3 is a substantially triangular shape (FIG. 6).
• preferred shapes of the linear protrusion 34 include a substantially triangular shape (FIG. 7 (a)), a substantially trapezoidal shape (FIG. 7 (b)), and a substantially arc shape (FIG. 7 (c) )), Substantially bell-shaped (Fig. 7 (d)), modified versions (Fig. 7 (e)), and mixtures thereof. Moreover, the shape similar to these shapes may be sufficient.
• the cross-sectional shape of the linear groove 33 or the linear protrusion 34 is symmetric, but is not limited thereto, and the light incident surface 31 side and the opposite side are asymmetric. It may be a certain shape. Further, the linear groove 33 and the linear protrusion 34 may be mixed.
• the angle formed between the slope of the linear protrusion 34 provided on the light guide 3 on the opposite side of the light source 1 and the straight line perpendicular to the light source 1 is shown in Figs. 7 (a) and 7 (b).
• the angle ⁇ 2 is formed by a straight line L1 parallel to the xy plane and perpendicular to the light source 1 and a slope located on the opposite side of the light source 1 of the linear protrusion 34.
• Figs. 7 (c) to (e) when the angle formed by a slope changes within one slope, the average value of the slope of the tangent of that slope is calculated on the opposite side of the light source 1 of the linear protrusion 34.
• the angle ⁇ 2 formed by the slope located at and the straight line perpendicular to the light source 1 is defined as ⁇ 2.
• the angle ⁇ 1 formed by the slope located on the light source 1 side in the linear groove 33 provided in the light guide 3 and the straight line perpendicular to the light source 1 or provided in the light guide 3 By controlling the angle ⁇ 2 between the inclined surface located on the opposite side of the light source 1 in the linear protrusion 3 4 and the straight line perpendicular to the light source 1, the light emission characteristics from the light guide 3 are controlled. Can do. Note that if ⁇ 1 or ⁇ 2 is less than 20 ° or exceeds 50 °, the amount of light emitted from the light guide 3 may decrease. When a plurality of light sources are used, ⁇ 1 or ⁇ 2 may be the above value between at least one light source and the linear groove 33 or the linear protrusion 34.
• the slope located on the light source 1 side in the linear groove 33 provided in the light guide 3 or the slope located on the opposite side of the light source 1 in the linear protrusion 34 provided in the light guide 3 is smooth. It is preferable.
• the term “smooth” as used herein means that when the surface roughness Ra of the oblique surface is measured based on JIS-B0601 (2001 edition), the value is 50 nm or less. More preferably, it is 20 nm or less, more preferably 10 nm or less, and particularly preferably 5 nm or less.
• the surface roughness Ra of the slope facing the light source 1 of the linear groove 33 or linear protrusion 34 of the light guide 3 exceeds 50 nm, the light reflection efficiency at the surface of the linear groove 33 or linear protrusion 34 decreases. As a result, the light utilization efficiency of the light guide 3 may be reduced.
• Surface roughness of the slope located on the light source 1 side in the linear groove 33 provided in the light guide 3 or the slope located on the opposite side of the light source 1 in the linear protrusion 34 provided in the light guide 3 By setting Ra to 50 nm or less, the light reflection efficiency on the surface of the linear groove 33 or the linear protrusion 34 can be increased. As a result, it is possible to obtain a surface light source with high light utilization efficiency.
• the flat surface between the linear groove 33 or the linear protrusion 34 is compliant with JIS-B0601 (2001 edition).
• the surface roughness Ra based on is preferably 50 nm or less. More preferably, it is 20 nm or less, more preferably lOnm or less, and particularly preferably 5 nm or less.
• Ra of the flat surface between the linear grooves 33 or the linear protrusions 34 exceeds 50 nm, up to the termination surface facing the light incident surface 31 away from the light source 1 (when the light source 1 is installed on both sides) A large amount of light is emitted from the light exit surface 32 before the light propagates.
• the in-plane uniformity of the brightness may be lowered, or the center brightness may be lowered.
• Ra of the flat surface between the linear grooves 33 or the linear protrusions 34 to be 50 nm or less, a surface light source having excellent luminance characteristics can be formed even in a large area.
• the depth HI (Fig. 6) of the linear groove 33 of the light guide 3 or the height H2 (Fig. 7) of the linear protrusion 34 is; preferable. More preferably;! To 200 ⁇ m, more preferably 1 to 100 Hm. If Hl and H2 are less than 1 ⁇ m, the linear groove 33 or the linear protrusion 34 is too small to be easily formed, and even if it can be formed, it will propagate through the light guide 3. In some cases, the function of changing the direction of light is poor. Molding tends to be difficult even if Hl and H2 exceed 500 m.
• the depth HI of the linear groove 33 of the light guide 3 or the height H2 of the linear protrusion 34 within the range of 1 to 500 111, both the formability of the light guide 3 and the light utilization efficiency are achieved. The power S to do.
• the light that enters and propagates into the light guide 3 the light that collides with the linear grooves 33 or the linear protrusions 34 changes its traveling direction, and the light exit surface 32 has an angle that is less than the critical angle. Incident light is emitted outside the light guide 3. For this reason, the amount of light propagating through the light guide 3 decreases as the distance from the light source 1 increases. That is, the probability of light collision by location is the same. Therefore, if only the linear grooves 33 or the linear protrusions 34 having the same shape and the same size are formed, the side closer to the light source 1 becomes brighter in proportion to the amount of light in the light guide 3.
• the probability of light collision with the linear groove 33 or the linear protrusion 34 should be increased according to the distance from the light source 1. Specifically, according to the distance from the light source 1, (A) the depth HI of the linear groove 33 or the height H2 of the linear protrusion 34 shown in FIGS. 6 and 7 is increased, (B) the linear groove 33 or (C) Increase the depth HI of the linear groove 33 shown in FIGS. 6 and 7, or the height H2 of the linear protrusion 34, and increase the linear groove 33 or linear shape. For example, the pitch of the protrusions 34 can be reduced.
• the depth HI of each linear groove 33 of the light guide 3 or the height H2 of the linear protrusion 34 is equal to the depth HI or high in the length direction of one linear groove or linear protrusion.
• Depth HI or height H2 may be changed. As an example where the depth HI or the height H2 changes, if there is a portion where light from the light source 1 is difficult to reach in the direction parallel to the light source 1, the depth HI or linear shape of the linear groove 33 at that portion If the height H2 of the protrusion 34 is increased or there is a part where light is excessively propagated, the force S can be reduced by reducing the depth HI of the linear groove 33 or the height H2 of the linear protrusion 34. . As a result, the amount of emitted light in the plane of the light body 3 can be adjusted, so that a desired luminance distribution can be obtained.
• the pitch P which is a repeating unit of the linear groove 33 or the linear protrusion 34 of the light guide 3, is 10 to 1000 ⁇ m. Preferable (20 to 600 mm, more preferably (30 to 400 mm). If the pitch P is less than lO rn, it is too small and molding is difficult. Pitch P force OOO m In the case of exceeding the above, the luminance uniformity in the portion where the linear groove 33 or the linear protrusion 34 is formed and the portion where the linear protrusion 34 is not formed may decrease. By setting the pitch P of the linear grooves 33 or the linear protrusions 34 within the range of 10 to 1000 ⁇ m, both the moldability of the light guide 3 and the light utilization efficiency can be achieved. Even when the pitch P of the linear groove 33 or the linear protrusion 34 is changed according to the distance from the light source by the method (B) or (C) described above, the range of 10 to 1000 m It is preferable to change within.
• the shape of the light incident surface 31 of the light guide 3 is not particularly limited as long as the light source 1 is a linear light source such as a fluorescent tube or a cold cathode tube.
• the portion corresponding to the front of the LED is a bright line.
• the area in front of the LED—LED may become a dark line.
• the shape of the light incident surface 31 may be an uneven shape such as a substantially arc shape, a substantially prism shape, a substantially trapezoidal shape, or a substantially dome shape.
• the thickness of the light guide 3 depends on the screen size. Usually 0.1 mm to 20 mm, more preferred, ⁇ 0 ⁇ 1 mm to 5 mm, more preferably (or 0 ⁇ lmm to lOmm.
• the light guide 3 need not have a constant thickness, and is far from the light incident surface 31.
• the thickness of the light guide 3 is thinner than that of the light source 1, the thickness near the light incident surface 31 of the light guide 3 is increased to improve the light utilization efficiency, and An inclined portion may be formed so that only the light emitting surface 32 portion is thinned.
• the light guide 3 used for the surface light source of the present invention is manufactured as follows.
• the light guide 3 of the present invention can be produced by methods such as injection molding and imprinting.
• the linear grooves 33 or the linear protrusions 34 can be formed with high accuracy.
• the imprint method is preferred because it can be molded with good reproducibility.
• both the injection molding and the imprint method can be suitably used.
• the light guide 3 can be obtained by cutting into a desired shape after molding and polishing the side surface portion.
• the resin constituting the light guide 3 includes certain refractions such as acrylic resins such as PMMA, polycarbonate resins, polypropylene resins such as polypropylene, polyisobutylene, polybutene, and polymethylpentene, and cycloolefin resins. It is preferable to use a transparent resin material having a ratio.
• the reflection sheet 4 is provided on the light non-emitting surface 35 side of the light guide 3.
• the reflection sheet 4 reflects the light emitted from the light non-emitting surface 35 of the light guide 3 to the light guide 3.
• the characteristics, material, and structure of the reflection sheet 4 are the same as those of the reflector 2 described above.
• the surface light source of the present invention is characterized in that a specific first optical film 5 is provided on the light emitting surface 31 of the light guide 3.
• the first optical film 5 has anisotropic diffusibility, and the direction in which the anisotropic diffusibility is maximum is substantially parallel to the longitudinal direction of the linear groove 33 or the linear protrusion 34. It is arranged to become.
• anisotropic diffusivity refers to the emission angle distribution of light that is transmitted when a light beam is incident from a direction perpendicular to the film surface using an automatic goniophotometer. When measured at 1 °, the spread of transmitted light differs depending on the measurement direction.
• a known device may be used for the automatic goniophotometer.
• an automatic goniophotometer GP 200 (Murakami Color Research Laboratory) or an automatic goniophotometer having functions equivalent to or better than this may be used.
• the light amount (T / 2) is half the light output T in the normal direction.
• the anisotropic diffusivity is a value measured by entering from a smoother surface.
• the "direction in which the anisotropic diffusibility is maximized” is a measurement direction in which the half-value width D of the transmitted light is maximized.
• the “direction in which the anisotropic diffusivity is minimum” is a measurement direction in which the half-value width D of the transmitted light is minimum.
• the direction in which the anisotropic diffusivity of the first optical fin 5 is maximized and the length direction of the linear groove 33 or the linear protrusion 34 of the light guide 3 are arranged substantially in parallel. . Thereby, the force S for efficiently using the light emitted from the light guide 3 is reduced. As a result, a surface S with high brightness can be obtained with the force S.
• the substantially flat fi is the direction in which the longitudinal direction (dl) of the linear groove 33 or the linear protrusion 34 and the anisotropic diffusion of the first optical film 5 are maximized.
• the angle ⁇ 5 formed by (d2) is within 0 ⁇ 15 °. More preferably, ⁇ 5 is within 0 ⁇ 10 °, more preferably within 0 ⁇ 5 °.
• ⁇ 5 be the angle between the direction of and.
• the first optical film 5 has a half-value width Dlmax of transmitted light in a direction in which anisotropic diffusivity is maximized when light is incident from the normal direction, and light is incident from the normal direction. It is preferable that the ratio Dlmax / Dlmin of the half-value width Dlmin of transmitted light in the direction in which the anisotropic diffusivity is minimum is 3 or more. More preferably, Dlmax / Dlmin is 5 or more, and further preferably Dlmax / Dlmin is 7 or more. If Dlmax / Dlmin is less than 3, The light emitted from the light emitting surface 32 of the light body 3 may be scattered more than necessary or the luminance may be lowered.
• the light emitted from the light emitting surface 32 of the light guide 3 can be transmitted with high efficiency.
• a high-luminance surface light source can be obtained.
• a high brightness improvement effect can be obtained.
• the first optical film 5 preferably has a half-value width Dlmin of transmitted light in a direction in which anisotropic diffusivity is minimized when light is incident from the normal direction to 10 ° or less. More preferably, it is 7 ° or less, more preferably 5 ° or less. If Dlmin exceeds 10 °, the light emitted from the light exit surface 32 of the light guide 3 may be scattered more than necessary or the luminance may be lowered.
• the surface light source of the present invention the light emitted from the light emitting surface 32 of the light guide 3 can be transmitted with high efficiency by setting the Dlmin of the first optical film 5 to 10 ° or less. As a result, a high-luminance surface light source can be obtained. Further, when using the second optical film 6 described later, a high luminance improvement effect can be obtained.
• the first optical film 5 preferably has a total light transmittance of 45% or more. More preferably, the total light transmittance is 50% or more.
• the total light transmittance here is the amount of light transmitted through the film relative to the amount of incident light when light is incident on the film using a light source (preferably a standard light source, see JIS Z-8720 (2000 edition)). Refers to the ratio. In the case where an uneven shape is formed on one surface of the optical film 5, the value measured by making it incident from a smoother surface is taken as the total light transmittance. When concave and convex shapes are formed on both surfaces of the optical film 5 or when both surfaces are smooth, the larger value of the values measured by entering from both surfaces is the total light Transmittance.
• the total light transmittance of the first optical finer 5 is less than 45%, the light emitted from the light guide 3 may not be used efficiently. Thus, by setting the total light transmittance of the first optical film 5 to 45% or more, a high-luminance surface light source can be obtained.
• the first optical film 5 preferably has a haze of 70% or more. More preferably, the haze is 75% or more, and still more preferably, the haze is 80% or more.
• Haze here refers to the percentage of the amount of light that is scattered and transmitted by more than 2 ° from the incident light beam while the incident light passes through the sample from the light source (preferably the standard light source, JIS Z-8720 (2000 edition)). H)
• T diffuse transmittance
• ⁇ total light transmittance
• linear transmittance ⁇
• the value measured by making it incident from a smoother surface is taken as the haze value. If both surfaces of the optical film 5 are uneven, or if both surfaces are smooth, the value of the larger or smaller of the values measured by entering from both surfaces! Is the haze value. If the haze is less than 70%, light cannot be sufficiently diffused, and the in-plane luminance distribution as a surface light source and the viewing angle characteristics may deteriorate.
• the surface light source of the present invention by setting the haze of the first optical film 5 to 70% or more, a surface light source having high brightness and excellent viewing angle characteristics can be obtained.
• the first optical film 5 more preferably has a total light transmittance of 45% or more and a haze of 70% or more. More preferably, the total light transmittance is 50% or more, the haze is 75% or more, particularly preferably the total light transmittance is 50% or more, and the haze is 80% or more. When the total light transmittance of the first optical film 5 is 45% or more and the haze is 70% or more, a high-luminance surface light source can be obtained.
• FIG. 10 is a diagram showing an example of the first optical film in the present invention.
• rod-shaped particles including rod-shaped and spindle-shaped
• a refractive index different from that of the resin constituting the film are arranged in one direction to develop anisotropic diffusibility. It may be a thing.
• a plurality of cross-sectional shapes such as those shown in Figs. 10 (b) and 10 (c) that are curved and arranged in a stripe in one direction, or a spindle-like shape that is cut in half as shown in Fig. 10 (d).
• An anisotropic diffusivity may be developed by providing irregularities on at least one surface of the film, represented by an array shape.
• the cross-sectional shape may be regular as shown in FIG. 10 (b) or irregular as shown in FIGS. 10 (c) and 10 (d).
• FIGS. 10 (c) and 10 (d) are examples of the cross-sectional shape.
• the first optical film 5 When a film that exhibits anisotropic diffusivity due to the surface shape is used as the first optical film 5, irregularities are provided when the first optical film 5 is placed on the light guide 3. It is preferable to mount so that the surface is located in the direction of the viewer. This is because it becomes easy to control the emission distribution from the surface light source.
• the thickness FL1 of the first optical film 5 is preferably 30 to 1000 ⁇ m in terms of the handleability and workability of the film. More preferably, it is 50-700 ⁇ 111, and particularly preferably 75-500111.
• the film thickness FL1 is the thickness of the film when the surface is smooth as shown in FIG. 10 (a), and the shape is provided only on one surface as shown in FIG. 10 (b).
• unevenness is provided on both sides, it means the thickness from the apex of the convex part on one surface to the apex of the convex part on the other side. As shown in Figs.
• the optical film (1) 1 has a thickness FL1 of 5.
• the first optical film 5 is manufactured, for example, as follows.
• a method in which the sheet is stretched at least uniaxially so that the rod-shaped particles inside are aligned in one direction, and a resin in which incompatible thermoplastic resins having different refractive indexes are dispersed is processed into a sheet.
• the manufacturing force can be increased by extending the dispersed thermoplastic resin into a rod shape and arranging it in one direction.
• the material of the resin material, the rod-like particles, and the incompatible resin is not particularly limited, and any combination having different refractive indexes can be preferably used.
• a film that forms irregularities on at least one surface of the film may be, for example, a coating containing rod-shaped particles.
• the method of coating on the film surface while controlling the direction of the particles, the method of providing irregularities on the surface by hairline processing (processing to scratch the film surface), the method of providing irregularities on the surface by the thermal imprint method or the optical imprint method, etc. Can be manufactured.
• the uneven shape and size From the viewpoint of being controllable, the thermal imprint method and the optical imprint method are particularly preferable.
• the thermal imprint method is a method of heating a mold having a fine surface shape and a resin film (base film) of a substrate, pressing the mold against the substrate film, cooling, and releasing the mold. This is a technique for transferring the shape applied to the mold surface to the base film.
• the resin used for the thermal imprinting method may be a thermoplastic resin or a thermosetting resin, but a highly transparent resin is preferred.
• resins suitable for thermal imprinting include polyester resins such as polyethylene terephthalate, polyethylene 2, 6 naphthalate, polypropylene terephthalate, and polybutylene terephthalate, polyethylene, polystyrene, polypropylene, polyisobutylene, polybutene, and polybutene.
• Polyolefin resins such as methylpentene, cycloolefin resins, polyamide resins, polyimide resins, polyether resins, polyester amide resins, polyether ester resins, acrylic resins, polyurethane resins, polycarbonate resins, Polychlorinated bur resin can be used.
• polyester resins are particularly preferred because of the variety of monomer types to be copolymerized and the ease of adjusting the material properties. It is preferably mainly composed of a thermoplastic resin selected from an acrylic resin or a mixture thereof.
• these resins have high crystallinity, they may crystallize in the preheating step during thermal imprinting, and may become white or have poor moldability. For this reason, it is more preferable to use an amorphous resin which is preferably used with low crystallinity.
• an amorphous resin which is preferably used with low crystallinity.
• isophthalic acid, cyclohexanedimethanol, bisphenol A, 2, 6 naphthalenedicarboxylic acid, spiroglycol, 9, 9, monobis (4 Roxyethoxyphenyl) fluorene, etc. is copolymerized to reduce resin crystallization.
• the photoimprint method is a state in which a photocurable resin is applied on a base film and then a mold having a fine surface shape is pressed against the photocurable resin layer, or on the mold. After the photocurable resin is applied to the substrate, the surface of the mold is released after irradiating with light such as ultraviolet rays from the mold side or the film side by curing the photocurable resin with the substrate film being overlaid. This is a technique to transfer the shape applied to the resin.
• electromagnetic waves Can be used as long as it reacts within or between molecules by the action of cross-linking, and can be used.
• a butyl group, a vinylidene group, an attalyloyl group, a methacryloylole group [hereinafter referred to as an atalyloyl group and a methacryloyl group] can be used.
• a (meth) atalyloyl group is referred to as (meth) atalyloyl group.
• the same expression is used for (meth) acrylic, (meth) acrylate, and the like. ]
• Maleimide groups, epoxy groups, and the like can be used.
• a compound having a (meth) attalyloyl group, an epoxy group or an oxetane group is preferably used.
• oligomers and oligomers that can be cross-linked by electromagnetic radiation include unsaturated polyesters such as unsaturated dicarboxylic acid and polyhydric alcohol condensates, polyester (meth) acrylate, polyether (meth) acrylate, polyol (Meta) Atalylate, Melamine (Meth) Atalylate Cationic Polymerization Type Epoxy Compound
• the first optical film 5 has various additives such as an antioxidant, a heat stabilizer, a weather stabilizer, an ultraviolet absorber, an organic solvent, and the like within a range that does not impair the effects of the present invention.
• Lubricants, pigments, dyes, fillers, antistatic agents, nucleating agents, and the like may be blended.
• the second optical film 6 is a sheet-like film that can change the emission angle distribution from the first optical film 5.
• the luminance of the surface light source can be increased, the uniformity can be increased, and the viewing angle can be controlled. As a result, the quality as a surface light source can be improved.
• the second optical film 6 include a prism sheet and a diffusion sheet having isotropic diffusibility (hereinafter referred to as “isotropic diffusible film”).
• FIG. 11 is a diagram showing an example of a prism sheet that can be used as the second optical film 6 in the present invention.
• the prism sheet for example, when the shape is constant over the plane (Fig. 11 (a)), when prisms of various heights are mixed (Fig. 11 (b)), When the pitch of the prism is mixed (Fig. 11 (c)), when the prisms of various prisms are mixed (Fig. 11 (d)), a combination of them can be used.
• the prism apex angle becomes an arc! /, Etc.
• the apex angle ⁇ 3 of the prism of the prism sheet is preferably 80 ° to 100 °. More preferably, ⁇ 3 is 83 to 97 °, and further preferably ⁇ 3 is 86 to 94 °. If the apex angle of the prism is less than 80 ° or more than 100 °, the light utilization efficiency from the light guide 3 through the first optical film 5 may decrease. By setting the apex angle ⁇ 3 of the prism sheet within a range of 80 to 100 °, a surface light source with high light use efficiency can be obtained. In addition, when prisms having different prism apex angles are mixed, the apex angles may be within the above range.
• the length direction of the prism is set substantially parallel to the direction in which the anisotropic diffusion property of the first optical film 5 is maximized.
• substantially parallel means, as shown in FIG. 12, that the angle ⁇ 6 formed by the prism length direction (d3) and the direction (d2) in which the anisotropic diffusion property of the first optical film 5 is maximum is It means within 0 ⁇ 15 °. More preferably, ⁇ 6 is within 0 ⁇ 10 °, and more preferably ⁇ 6 is within 0 ⁇ 5 °.
• an optical imprint method is preferably used. After the photocurable resin is applied on the base film, the photocurable resin layer is pressed against the mold having the prism shape formed thereon, or the photocurable resin is applied to the mold on which the prism shape is formed. After coating, with the base film overlapped, light such as ultraviolet rays is irradiated from the mold side or film side to cure the photo-curable resin, and then released to the mold surface. The formed shape can be formed on the film surface.
• the resin to be used the same resins as those mentioned in the case of the first optical film 5 can be used.
• the isotropic diffusive film that can be used as the second optical film 6 is a diffusion sheet having isotropic diffusibility.
• “isotropic diffusibility” means the half width D2max of transmitted light in the direction in which the diffusivity is maximum when light is incident from the normal direction of the second optical film 6, and In a direction that minimizes isotropic diffusivity when light is incident from the line direction
• Half-width of transmitted light D2min ratio D2max / D2min is 5 or less. More preferably, D2max / D2min is 3 or less, further preferably 2 or less, and most preferably D2max / D2min is 1.5 or less.
• the meanings of “the direction in which the diffusibility is maximized”, “the direction in which the diffusibility is minimized”, and “half width” are the same as those in the first optical film 5 described above. If the half-width ratio D2max / D2min exceeds 5, there is a possibility that the uniformity in the surface light source surface will decrease or that the luminance will change greatly depending on the viewing angle. In the surface light source of the present invention, when an isotropic diffusive film is used as the second optical film 6, the surface light source excellent in viewing angle characteristics and display characteristics can be obtained by setting the half width ratio D2max / D2min to 5 or less.
• the direction in which the anisotropic diffusivity of 5 is maximized and the direction in which the diffusibility of the second optical film is maximized are preferably substantially perpendicular to each other.
• substantially perpendicular means that the angle ⁇ 7 between the longitudinal direction of the adjacent linear grooves 33 or linear protrusions 34 and the direction in which the second optical film 6 has the maximum diffusivity is within 90 ⁇ 15 °. It means that. More preferably, ⁇ 7 is within 90 ⁇ 10 °, and more preferably within 90 ⁇ 5 °.
• the isotropic diffusive film preferably has a half-width D2min of transmitted light in the direction in which the diffusibility is minimized when light is incident from the normal direction, and the force S is preferable. More preferably 3 to 30 °, still more preferably 4 to 15 °. If D2min is less than 2 °, the linear groove 33 or the linear protrusion 34 of the light guide 3 may be visually recognized, the uniformity in the surface light source surface may be reduced, or the luminance may increase depending on the viewing angle. It can change. In addition, if the angle exceeds 50 °, the light use efficiency may decrease, and the luminance of the surface light source may decrease.
• the isotropic diffusive film preferably has a haze of 70% or more. More preferably, the haze is 75% or more, and still more preferably, the haze is 80% or more.
• the haze is a value measured by making the light incident from a smoother surface. If the haze is less than 70%, light cannot be sufficiently diffused, and the in-plane luminance distribution as a surface light source and the viewing angle characteristics may be deteriorated.
• the surface light source of the present invention by setting the haze of the second optical film 6 to 70% or more, a surface light source having high brightness and excellent viewing angle characteristics can be obtained.
• the definition of haze is the same as the definition of haze in the first optical film 6 described above.
• the isotropic diffusive film preferably has a total light transmittance of 50% or more and a haze of 70% or more. More preferably, the total light transmittance is 55% or more, the haze is 75% or more, particularly preferably the total light transmittance is 60% or more, and the haze is 80% or more.
• the total light transmittance is 50% or more and the haze to 70% or more, a surface light source having high luminance, excellent viewing angle characteristics and uniformity can be obtained.
• FIG. 13 shows a specific example of an isotropic diffusive film.
• an isotropic diffusive film for example, a film containing a spherical particle having a refractive index different from that of the resin constituting the film (FIG. 13 (a)), a film containing spherical particles is formed on the film surface. (Fig. 13 (b)), or a substantially dome-like shape obtained by cutting out a half of a substantially spherical shape (Fig. 13 (c)), etc., with a concavo-convex shape formed on at least one surface of the film, Or a combination of these. By adopting such a shape, isotropic diffusibility can be expressed.
• the cross-sectional shape of these films and concavo-convex shapes may be regular or irregular.
• An isotropic diffusive film in which irregularities are provided on at least one surface of the film is more preferable in that high diffusibility can be obtained and the light diffusibility can be easily controlled.
• the thickness FL2 of the isotropic diffusive film is a force of 30 to 1 000 ⁇ m in terms of the handleability and workability of the film ⁇ preferably, more preferably 50 to 700 ⁇ m, Particularly preferred is 75 to 500 111.
• the thickness FL2 of the film is the thickness when the surface is smooth as shown in Fig. 13 (a), and the shape is provided only on one surface as shown in Fig. 13 (b). Denotes the thickness from the apex of the convex part to the surface on the side where no shape is provided. In addition, when the shape is provided on both surfaces, it refers to the thickness from the top of the convex portion on one surface to the top of the convex portion on the other surface. As shown in FIG. 13 (c), when the height varies depending on the location, the average value is the thickness FL2 of the second optical film 6. The thickness of this film is the same for the prism sheet.
• an isotropic diffusive film having isotropic diffusibility inside the film It can be obtained by processing a resin material in which substantially spherical particles having different refractive indexes are dispersed into a sheet. In addition, stretching the sheet uniaxially or biaxially is also preferably performed in terms of improving the mechanical strength.
• the film stretched uniaxially or biaxially is given planar stability and dimensional stability, and voids (voids) formed between the substantially spherical particles having different refractive indexes and the resin as necessary. ) Is subsequently eliminated by heat treatment (heat setting) in the tenter, and after the heat treatment, the film is uniformly annealed and then cooled to near room temperature. A film is produced.
• a coating containing fine particles is used as a method for forming isotropic diffusibility by forming an uneven shape on at least one surface of the film as an isotropic diffusive film.
• a coating containing fine particles examples thereof include a method of applying an agent to the film surface, and a method of providing irregularities on the surface by a thermal imprint method or a photoimprint method.
• a thermal imprint method or a photoimprint method about the method by the thermal imprint method or the optical imprint method, it can be produced by the same method as the production method of the first optical film 5.
• the second optical film 6 used in the present invention various additives such as an antioxidant, a heat stabilizer, a weather stabilizer, and an ultraviolet absorber are used within the range in which the effects of the present invention are not impaired.
• Organic lubricants, pigments, dyes, fillers, antistatic agents, nucleating agents, and the like may be blended.
• the surface light source of the present invention uses the anisotropic diffusion film as the first optical film 5, the direction in which the diffusion property is maximized, and the linear grooves 33 or the linear protrusions 34 of the light guide 3. Brightness can be increased by arranging them substantially parallel to the direction. Furthermore, by arranging a specific film as the second optical film 6, it is possible to obtain a surface light source that has high brightness, excellent viewing angle characteristics, and excellent uniformity, which cannot be achieved by a conventional surface light source. . The details will be explained.
• FIG. 14 is a diagram showing the light transmission characteristics of the prism sheet.
• Light (il) incident on the prism sheet from near the normal direction repeats total reflection at the prism / air interface, and as a result, returns to the opposite direction of the normal and does not pass through the prism sheet.
• the returned light can be reused if it is reflected using a reflective sheet. it can. However, if reflection is repeated, the light beam is lost due to deactivation.
• the type of optical film and the emission characteristics from the light guide 3. it is important to control the type of optical film and the emission characteristics from the light guide 3. Specifically, when a prism sheet is used as the second optical film, it is important to increase the incident light at an incident angle of about ⁇ 30 °. In addition, when the second optical film is not provided, and when an isotropic diffusion sheet is used as the second optical film, it is important to increase the light in the normal direction. Based on the above concept, a mechanism for increasing the brightness of the surface light source of the present invention will be described with reference to FIGS.
• the surface light source of the present invention is not limited to these.
• FIG. 15 is a diagram schematically illustrating light that propagates through the light guide and exits.
• FIG. 15 (a) is a diagram schematically showing light propagating in the light guide 3.
• a triangular linear groove 33 is formed on the opposite side of the light emitting surface 32 as the light guide 3.
• the light incident surface 31 is also incident on the light that is parallel to the surface of the light guide 3 and propagates without hitting the light exit surface 32 and the light non-exit surface 35, and the light exit surface 32 or light of the light guide 3.
• the light that collides with the linear groove 33 is reflected on the surface of the linear groove 33, and the traveling direction thereof is changed.
• the light is incident on the light emitting surface 32 at a critical angle or less, and is emitted outside the light guide 3 (FIG. 15 (a), ⁇ 1, ⁇ 2, ⁇ 3).
• FIGS. 15B to 15G are diagrams schematically showing an optical path of light that collides with the linear groove 33 or the linear protrusion 34.
• the force of the linear projection 34 is an example of the linear groove 33.
• FIGS. 15 (b) and (e) are examples of light impinging on the linear groove 33 substantially parallel to the light guide surface
• FIGS. 15 (c) and 15 (f) are views of the linear groove 33 from the light emitting surface side 35.
• Examples of colliding light FIGS. 15D and 15G, show examples of light reflected from the non-light-emitting surface 35 and colliding with the linear groove 33.
• ⁇ 2 is the same as ⁇ 1 described above.
• the light ⁇ 2 that collides with the linear groove 33 from the light emitting surface 32 side is totally reflected so as to return to the light source 1 side on the inclined surface.
• the light ⁇ 3 reflected from the light non-emitting surface 35 side and colliding with the linear groove 33 is totally reflected in the direction opposite to the light source 1 side on the inclined surface.
• the angle ⁇ 1 formed by the slope located on the light source side in the linear groove provided in the light guide and the straight line perpendicular to the light source 1 is controlled, the light of the light guide 3 It can be seen that the light emitted from the emission surface 32 can be controlled. Specifically, when ⁇ 1 is 42.5 ° to 45 °, the force to emit many rays in an oblique direction, and when 61 ° is 0 to 42.5 °, Touch with S.
• FIG. 16 is a diagram for explaining an example of an emission angle distribution of outgoing light from the light outgoing surface 32 of the light guide 3 in the surface light source of the present invention.
• the exit angle distribution described in the example of FIG. 16 is as follows: in a surface light source in which two light sources 1 and a reflector 2 are opposed to each other with a light guide 3 interposed therebetween, as shown in FIG. 3 is an example showing an emission angle distribution from the central portion of the light exit surface 32 of the body 3.
• FIG. This is an example in which a triangular linear groove 33 is formed in a direction parallel to the light incident surface 31 as the light guide 3 on the light non-emitted surface 35 side.
• FIGS. 16A and 16C show the emission angle distribution in a plane perpendicular to the length direction of the linear groove 33 (hereinafter simply referred to as a plane perpendicular to the linear groove 33).
• FIGS. 16 (b) and 16 (d) show the emission in a plane parallel to the length direction of the linear groove 33 including the normal direction of the light emission surface 32 (hereinafter simply referred to as a plane parallel to the linear groove 33).
• FIG. 17 shows an anisotropic diffusion film or light source on a light guide 3 of a surface light source in a form in which two light sources 1 and a reflector 2 are opposed to each other with the light guide 3 interposed therebetween, as shown in FIG. 2 (a).
• Isotropic diffusion film It is an example which shows the emission angle distribution from the center part when mounting.
• FIGS. 17A and 17C show the emission angle distribution in the plane perpendicular to the linear groove 33.
• FIG. 17B and 17D show the emission angle distribution in a plane parallel to the linear groove 33.
• FIG. 17A and 17C show the emission angle distribution in the plane perpendicular to the linear groove 33.
• FIG. 17B and 17D show the emission angle distribution in a plane parallel to the linear groove 33.
• the linear groove 33 A large amount of light can be emitted in the vicinity of ⁇ 30 ° in the plane perpendicular to.
• a broad emission angle distribution having a maximum point in the vicinity of the ⁇ 40 ° direction is obtained (FIG. 16 (b)).
• the plane perpendicular to the linear groove 33 contains a lot of light in a direction suitable for the prism sheet.
• the power S can be emitted.
• other planes for example, in a plane parallel to the linear groove 33
• a lot of light is emitted in directions other than the direction suitable for the prism sheet. Therefore, if the light can be directed in a direction suitable for the prism sheet, it is possible to achieve high brightness with the force S.
• FIGS. 16 (a) and 16 (b) show the emission angle distribution when an anisotropic diffusion film or an isotropic diffusion film is installed on the emission surface 31 of the light guide 3 having the emission angle distribution.
• an isotropic diffusive film When an isotropic diffusive film is used, light is evenly diffused and the emission angle distribution from the light guide 3 is destroyed. That is, the light emitted from the light guide 3 is large in the vicinity of an emission angle of ⁇ 30 °, but the amount of light in the vicinity of the emission angle of ⁇ 30 ° is reduced when it further passes through the isotropic diffusive film. For this reason, the amount of emitted light in a direction suitable for the prism sheet is reduced, which is not preferable because efficiency is lowered.
• an anisotropic diffusion film having strong anisotropic diffusivity is arranged so that the direction in which the diffusibility is maximized and the length direction of the linear groove 33 are substantially parallel, they are perpendicular to the linear groove 33.
• light can be diffused only in the direction parallel to the length direction of the linear groove 33 (FIG. 17 (b)).
• the emitted light can be collected in the normal direction of the light emitting surface 32 in a plane parallel to the linear groove 33 that does not disrupt the emission angle distribution in the plane perpendicular to the linear groove 33. . This makes it possible to increase light at an angle suitable for the prism sheet.
• an anisotropic diffusion film is provided in another plane (for example, in a plane parallel to the linear groove 33), 0. Light emitted in directions other than the direction can be directed in the normal direction of the light exit surface 32 (FIG. 17 (d)).
• an isotropic diffusion film it is 0 ° in the direction perpendicular to the linear groove 33 and in other planes (for example, in the plane parallel to the linear groove 33) as compared with the anisotropic diffusion film.
• Light emitted in directions other than the direction can be directed in the normal direction of the light exit surface 32 (FIGS. 17 (c) and (d)). That is, by using an anisotropic diffusion film as the first optical film 5 and controlling the angle ⁇ 1 of the inclined surface on the light source 1 side of the linear groove 33 to 40 °, the light emission in the normal direction increases. I understand that
• the angle formed between the slope located on the light source 1 side in the linear groove 33 provided in the light guide 3 and the straight line perpendicular to the light source 1 or provided in the light guide 3 When the angle between the inclined surface located on the opposite side of the light source 1 in the linear protrusion 34 and the straight line perpendicular to the light source 1 is 20 ° to 42.5 °, the emission of light in the normal direction increases. Therefore, under this condition, even when the second optical film 6 is not used, it is possible to obtain a high-luminance surface light source.
• the surface light source of the present invention having the above configuration preferably has an in-plane luminance uniformity U of 65% or more. More preferably, it is 70% or more, more preferably 75% or more, and particularly preferably 80% or more.
• the luminance uniformity U here is a viewing angle 1 using a color luminance meter and measuring the luminance at 25 points in the surface light source shown in Fig. 18 (a) when the screen size is 5 inches or larger.
• the maximum brightness Bmax and the minimum brightness Bmin when measuring the brightness of 9 points in the surface light source shown in Fig. 18 (b) at the measurement viewing angle 0.2 ° From this, it is a value calculated from the following formula.
• a known color luminance meter can be used for measuring the uniformity. For example, it is preferable to use BM-7 / FAST (manufactured by Topcon Co., Ltd.) or equivalent or higher.
• the uniformity U is 65% or more, it is possible to obtain good display characteristics with the force S.
• the surface light source of the present invention preferably has a viewing angle in the vertical direction of the screen or a viewing angle in the horizontal direction of 20 ° or more, more preferably the viewing angle in the horizontal direction of the screen. Is preferably 20 ° or more. More preferably, it is 25 ° or more, and more preferably 30 ° or more.
• the viewing angle is a color luminance meter
• the center part of the surface light source is in the range of ⁇ 80 ° in the vertical direction of the screen, or the emission angle distribution in the range of ⁇ 80 ° in the horizontal direction of the screen every 2 °.
• the viewing angle of the light source By setting the viewing angle of the light source to a range of 20 ° or more, it is possible to obtain a surface light source that can be used in a wide range of applications without being restricted by the application.
• a known color luminance meter can be used for measuring the viewing angle.
• the surface light source of the present invention is not limited to the above configuration, and within the range where the effects of the present invention are not lost, between the second optical film 6 and between the light guide 3 / first optical film 5, Or the first optical field It is also possible to insert other films between Lum 5 and the second optical film 6. It is also possible to combine other films. Examples of films that can be used include other diffusion films, prism sheets, visual field control films, reflective polarizing plates, brightness enhancement films, polarization separation sheets, color tone correction films, and the like. As an example of its use, for example, by further disposing a diffusion film on the second optical film 6, the display quality can be improved and a further brightness enhancement effect can be obtained. Further, if the reflective polarizing plate is arranged so that its polarization axis coincides with the polarization axis of the liquid crystal display device, it is possible to increase the light use efficiency and to achieve higher luminance.
• the surface light source of the present invention is superior to conventional surface light sources in terms of light utilization efficiency, high brightness, and wide viewing angle, and is suitable for mobile phones, electronic notebooks, notebook PCs, monitors, TVs, It can be suitably used for applications in which a liquid crystal display element is irradiated from the back, such as various display media.
• the liquid crystal display device of the present invention is characterized by mounting the above-described surface light source.
• the surface light source of the present invention it is possible to obtain a clear liquid crystal display device having high luminance, excellent viewing angle characteristics and uniformity.
• the following method is used.
• the measuring device other devices may be used as long as the results are equal to or higher than those of the following evaluation methods.
• HGM-2DP Fully automatic direct reading made by Suga Test Instruments Co., Ltd. ⁇ 's computer HGM-2DP is used to measure the total light transmittance and haze of the film. In the film plane, measure at 5 different locations, and use the average value as the total light transmittance and haze.
• the standard light source (see JIS Z-8720 (2000)) is used as the light source.
• the total light transmittance and haze are values measured by making the light incident from a smoother surface when an uneven shape is formed on one surface of the optical film.
• the values measured by entering from both surfaces The larger one is straightforward.
• the light beam is incident from the direction perpendicular to the film surface, and the relative transmittance per 1 ° is measured to obtain the exit angle distribution.
• the half-value width Dmax in the direction in which the diffusivity is maximum and the half-value width Dmin in the direction in which the diffusivity is minimum are obtained. Measure in the same way at five locations on the film surface, find the average values of the half-value widths Dmax and Dmin, and obtain the half-value width ratio Dmax / Dmin from these average values.
• the magnification is 100 times (short focus)
• the scan interval is 0.1 mC
• the depth of the linear groove 33 of the light guide HI or the line Measure the height H 2 of the projection 34, the tilt angle ⁇ 1 or ⁇ 2 on the light source 1 side, and the surface roughness Ra of the light exit surface 32 of the light guide.
• the luminance at 9 points in the surface light source shown in Fig. 18 (b) was measured at a measuring viewing angle of 0.2 °.
• the obtained central luminance was determined according to the following criteria.
• center intensity is less than 6700cd / m 2 or more 6800cd / m 2: B central luminance 6600cd / m 2 or more 6700cd / m of less than 2: C center luminance is less than 6500cd / m 2 or more 6600cd / m 2: D When the center brightness is less than 6500cd / m 2 : E
• center intensity is less than 6200cd / m 2 or more 6300cd / m 2: B central luminance 6100cd / m 2 or more 6200cd / m of less than 2: C center luminance is less than 6000 cd / m 2 or more 6100cd / m 2: D When the center brightness is less than 6000 cd / m 2 : E
• A, B, C, and D are all good, and E is not good.
• A, B, C, and D are excellent in this order! /, (A is the best! /).
• a and B are good, and C is not good. A is the best.
• the emission angle distribution in the range of ⁇ 80 ° in the vertical direction of the screen or ⁇ 80 ° in the horizontal direction of the screen is measured every 2 °.
• the luminance in the normal direction is half that of luminance B (B / 2)
• the viewing angle was the angular width (half-value width w) at 0 0.
• a and B are good, and C is not good. A is the best.
• the shape of the light guide used in Examples and Comparative Examples and the production method are as follows.
• the depth of each linear groove varies irregularly along the length of the groove.
• the average depth of the linear groove closest to the light incident surface is 11 m.
• the average depth of the linear groove is deeper as the linear groove is farther from the light incident surface.
• the average depth of the central linear groove is 33 m.
• the depth of each linear groove varies irregularly along the length of the groove.
• the average depth of the linear groove closest to the light incident surface is 10 m.
• the average depth of the linear groove is deeper as the linear groove is farther from the light incident surface.
• the average depth of the central linear groove is 36 m.
• the depth of each linear groove varies irregularly along the length of the groove.
• the average depth of the linear groove closest to the light incident surface is 12 m.
• the average depth of the linear groove is deeper as the linear groove is farther from the light incident surface.
• the average depth of the central linear groove is 34 ⁇ m.
• a mold with the above shape inverted and a 6mm thick polycarbonate resin "Iupilon" HL-4000 (Mitsubishi Engineering Plastics Co., Ltd.) resin plate is heated to 160 ° C, followed by 500kN Pressed for 30 seconds. Next, after cooling to 80 ° C, the pressure was released and the mold was released. The outer periphery of the obtained molded product was cut to adjust the shape, and the light guide 3 was obtained.
• "Iupilon" HL-4000 Mitsubishi Engineering Plastics Co., Ltd.
• the depth of each linear groove varies irregularly along the length of the groove.
• the average depth of the linear groove closest to the light incident surface is 11 m.
• the average depth of the linear groove is deeper as the linear groove is farther from the light incident surface.
• the average depth of the central linear groove is 36 m.
• the depth of each linear groove varies irregularly along the length of the groove.
• the average depth of the linear groove closest to the light incident surface is 2 m.
• the average depth of the linear groove is deeper as the linear groove is farther from the light incident surface.
• the average depth of the central linear groove is 31 m.
• optical films used in Examples and Comparative Examples are as follows.
• Cylindrical lens shape (Semi-elliptical shape with a cross section in the length direction of 50 m in height and 50 m in width arranged on the film surface at a pitch of 40 m (see Fig. 19))
• Manufacturing method It was manufactured by the same method as B-1, except that a mold having the above shape inverted was used as the mold.
• Shape A semi-spindle-shaped projection with a major axis of 200 ⁇ m, a minor axis of 20 ⁇ m, and a height of 20 ⁇ m arranged on the film surface. (See Figure 20)
• Manufacturing method It was manufactured by the same method as B-1, except that a mold having the above shape inverted was used as the mold.
• Rod-like particles arranged in one direction inside the film. Average minor axis of rod-shaped particles 3 ⁇ m, average major axis 500 ⁇ m
• PET Polyethylene terephthalate
• isophthalic acid component with respect to the acid unit
• cyclohexanedi with respect to the glycol unit.
• Pellets prepared by mixing 94% by volume of polyester resin (melting point TB: 225 ° C) with 10 mol% of the methanol component and 6% by volume of polymethylpentene (Mitsui Chemicals) as a light diffusing element were supplied.
• PET melting point TA: 265 ° C pellets were supplied to this sub-extruder.
• the extruded resin was cooled on a cast drum rotating at a speed twice the extrusion speed by an electrostatic application method to produce a three-layer laminated sheet.
• This laminated sheet was stretched 3.2 times in the longitudinal direction at a temperature of 87 ° C, and subsequently stretched 3.4 times in the width direction at 110 ° C through a preheating zone of 95 ° C. Further, the film was heat-treated at a heat treatment temperature Th of 235 ° C. for 30 seconds to obtain a 180 m thick film containing rod-like particles arranged in the film running direction.
• a diffusion film “TEXCELL” TDS 127 made by Toray Sehan was used.
• a diffusion film UTEII manufactured by Millea Nanotech was used.
• Manufacturing method It was manufactured by the same method as B-1, except that a mold having the above shape inverted was used as the mold.
• a diffusion film "TEXCELL" TDA128 made by Toray Sehan was used.
• a diffusion film DX2 manufactured by Kimoto Co., Ltd. was used.
• a 3M prism sheet BEFIII90 / 50T was used.
• a prism sheet THIN-T2 manufactured by Millea Nanotech was used.
• Manufacturing method 160 ° between a mold (vertical 280mm X horizontal 350mm) with the above shape inverted and a 0.2mm thick polycarbonate resin "Iupilon" HL-4000 (Mitsubishi Engineering Plastics Co., Ltd.) Heated to C, followed by pressing at 500kN for 30 seconds. Next, after cooling to 80 ° C., the pressure was released and the mold was released to obtain an optical film.
• the maximum half-value width Dmax, minimum value Dmin, Dmax / Dmin, transmittance of all light springs, haze, prism sheet apex angle ⁇ 3, prism pitch, prism Tables 2 and 3 show the height.
• the light guide A-1 is installed so that the surface on which the linear grooves are not formed is on the viewer side, and two cold cathode fluorescent lamps (hereinafter referred to as CCFLs) are provided on the two light incident surfaces facing each other.
• the “Lumirror” E6SV manufactured by Toray Industries, Inc.
• a reflection sheet “Lumirror” E6SL manufactured by Toray Industries, Inc. was installed on the non-observer side of the light guide 3.
• the CCFL was turned on by supplying a power supply voltage of 12V to this surface light source.
• a surface light source was produced in the same manner as in Example 11 except that B-2 was used as the first optical film.
• a surface light source was used in the same manner as in Example 11 except that B-3 was used as the first optical film. Produced.
• a surface light source was produced in the same manner as in Example 11 except that B-4 was used as the first optical film.
• a surface light source was produced in the same manner as in Example 11 except that C 2 was used as the second optical film.
• a surface light source was produced in the same manner as in Example 11 except that C3 was used as the second optical film.
• a surface light source was produced in the same manner as in Example 11 except that C 4 was used as the second optical film.
• a surface light source was fabricated as in 1.
• a surface light source was fabricated as in 1-1.
• the light guide A-1 is installed so that the surface on which the linear grooves are not formed is on the viewer side, one CCFL is placed on each of the two light incident surfaces facing each other, and a reflector is formed around it.
• "Lumilar” E6SV manufactured by Toray Industries, Inc.
• a reflective sheet “Lumirror” E6SL manufactured by Toray Industries, Inc.
• the surface light source was fabricated by installing the The first optical film (2) was installed so that the uneven surface was on the viewer side.
• CCFL was turned on by supplying a power supply voltage of 12V to this surface light source.
• the first optical film (2) was installed so that the concavo-convex surface was on the observer side, and the LED was turned on by supplying a power supply voltage of 15 V to this surface light source.
• the light guide A-4 is installed so that the surface where the linear groove is not formed is on the viewer side, and three LEDs are placed in parallel to the light incident surface.
• "E6SV manufactured by Toray Industries, Inc.
• a reflection sheet “Lumirror” E6SL manufactured by Toray Industries, Inc.
• the surface light source was produced by installing the illuminator. Both the first optical fin and (2) were installed so that the uneven surface was on the observer side. The surface light source was supplied with a power supply voltage of 3.3V to light the LED.
• Example 4 A surface light source was produced by laminating the same film as in Examples 12 to 110 on the light guide of Example 1.
• the surface light source was supplied with a power supply voltage of 3.3V to light the LED.
• Light guide A-5 is installed with a linear groove formed! /, Na! /, So that the surface is on the viewer side, and two CCFLs are placed on each of the two light incident surfaces facing each other.
• a “Lumirror” E6SV manufactured by Toray Industries, Inc.
• a reflective sheet “Lumirror” E6SL manufactured by Toray Industries, Inc.
• a surface light source was fabricated by installing ⁇ -6 as the second optical film on top of it.
• the first optical film (2) was installed so that both concave and convex surfaces were on the viewer side.
• a power supply voltage of 12V was supplied to the surface light source to light the CCF L.
• a surface light source was produced in the same manner as in Example 5-1, except that B-2 was used as the first optical film.
• a surface light source was produced in the same manner as in Example 5-1, except that B-3 was used as the first optical film.
• a surface light source was produced in the same manner as in Example 5-1, except that B-4 was used as the first optical film.
• a surface light source was produced in the same manner as in Example 5-1, except that B-7 was used as the second optical film.
• a surface light source was produced in the same manner as in Example 5-1, except that B-8 was used as the second optical film.
• a surface light source was produced in the same manner as in Example 5-1, except that B-9 was used as the second optical film.
• a surface light source was fabricated as in 5-1.
• a surface light source was fabricated in the same manner as in 5-1.
• Light guide A—7 is installed with a linear groove formed on it! /, N! /, The surface is on the viewer side, 49 LEDs are placed parallel to the light incident surface, and reflectors around it.
• “Lumilar” E6SV manufactured by Toray Industries, Inc.
• a reflective cider mirror “E6SL manufactured by Toray Industries, Inc.
• B-1 was used as the first optical film on the viewer side of the light guide 3 in the direction with the greatest anisotropic diffusion.
• the surface light source was installed and the first optical film (2) was installed so that the uneven surface was on the viewer side. It was.
• Light guide A-8 is installed with a linear groove formed on it! /, Na! /, The surface is on the viewer side, and three LEDs are placed parallel to the light incident surface, and a reflector around it.
• “Lumilar” E6SV manufactured by Toray Industries, Inc.
• Reflector sheet "Lumirror” E6SL Toray ( Co., Ltd.) was installed.
• a surface light source was produced by installing B-6 as a second optical film on the optical film B-1.
• the first optical film (2) was installed so that the concavo-convex surface was on the observer side.
• the surface light source was supplied with a power supply voltage of 3.3V to turn on the LEDs.
• uniformity U was 82%, and it was found that the center luminance and uniformity U were excellent.
• the viewing angle was 39 ° in the vertical direction and 41 ° in the horizontal direction, indicating good viewing angle characteristics (see Table 7).
• a surface light source was produced by laminating the same film as Example 5-2 to 5-10 on the light guide of Example 8-1.
• the surface light source was supplied with a power supply voltage of 3.3V to light the LED.
• a surface light source was produced in the same manner as in Example 11 except that B-5 was used as the first optical film.
• a surface light source was produced in the same manner as in Example 1-1 except that B-6 was used as the light turning angle film (1).
• a surface light source was produced in the same manner as in Example 11 except that B 7 was used as the first optical film.
• a surface light source was fabricated as in 1-1.
• a surface light source was produced in the same manner as in Example 2 except that B-5 was used as the first optical film.
• a surface light source was produced in the same manner as in Example 4 except that B-5 was used as the first optical film.
• Example 4 1-1 A surface light source was produced by laminating the same film as in Comparative Example 1 1-1 2; The surface light source was supplied with a power supply voltage of 3.3V to light the LED.
• a surface light source was produced in the same manner as in Example 51 except that B-6 was used as the first optical film.
• a surface light source was produced in the same manner as in Example 5-1, except that B-8 was used as the first optical film and B-8 was used as the second optical film.
• a surface light source was produced in the same manner as in Example 5-1, except that B-9 was used as the first optical film and B-9 was used as the second optical film.
• Example 5-1 The same as Example 5-1 except that B-7 was placed as the first optical film so that the direction with the greatest anisotropic diffusivity and the length direction of the linear groove of the light guide were parallel to each other. Thus, a surface light source was produced.
• a surface light source was produced in the same manner as in Example 5-1, except for the above.
• a surface light source was fabricated as in 1-1.
• a surface light source was produced in the same manner as in Example 6 except that B-6 was used as the first optical film.
• a surface light source was produced in the same manner as in Example 7 except that B-6 was used as the first optical film.
• a surface light source was produced in the same manner as in Example 8 except that B-6 was used as the first optical film.
• a surface light source was fabricated by laminating the same film as Comparative Example 8-2-8-7 on the light guide of Example 8-1.
• the surface light source was supplied with a power supply voltage of 3.3V to light the LED.
• Tables 4-7 The results of the above Examples and Comparative Examples are shown in Tables 4-7.
• Each table shows the type of light source used, the type of light guide used, the relationship between the first optical film type and linear groove direction and the maximum diffusion direction of the first optical film, and the second optical film.
• the evaluation shows the type, the relationship between the maximum diffusion direction of the first optical film and the prism length direction of the second optical film, the central luminance, the uniformity, and the viewing angle.
• Examples 1 1 to 1 10 of the configuration of the present invention using a 17-inch light guide A-1 and a prism sheet as the second optical film have good central luminance. It can be seen that the uniformity and viewing angle characteristics are excellent.
• Comparative Examples 11, 1, 2, 2, and 3 using isotropic diffusive sheets B-6 and B-6 have good uniformity U and viewing angle characteristics, but the central luminance is low. Recognize.
• Comparative Example 5-5 in which the relationship between the linear groove direction of the light guide and the maximum diffusion direction of the first optical film is perpendicular, and Comparative Example 5-6 in which they are not parallel are It can be seen that the center luminance is low, although good uniformity U and viewing angle characteristics are obtained.
• Comparative Example 8-5 in which the relationship between the linear groove direction of the light guide and the maximum diffusion direction of the first optical film is perpendicular, and Comparative Example 8-6 in which they are not parallel are It can be seen that the center luminance is low, although good uniformity U and viewing angle characteristics are obtained.
• the surface light source of the present invention is superior to conventional surface light sources in terms of excellent light utilization efficiency, high luminance, and wide viewing angle, and is suitably used for applications in which a liquid crystal display element is irradiated from the back side. be able to. Further, if the surface light source of the present invention is used, a high-brightness and clear liquid crystal display device can be obtained. Applications include mobile phones, electronic notebooks, notebook PCs, monitors, and TVs.

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• 2007
  • 2007-09-28 WO PCT/JP2007/068941 patent/WO2008038754A1/ja active Application Filing
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