WO2011090125A1 - Light control plate, surface light source device, and transmission-type image display device - Google Patents

Light control plate, surface light source device, and transmission-type image display device Download PDF

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Publication number
WO2011090125A1
WO2011090125A1 PCT/JP2011/050999 JP2011050999W WO2011090125A1 WO 2011090125 A1 WO2011090125 A1 WO 2011090125A1 JP 2011050999 W JP2011050999 W JP 2011050999W WO 2011090125 A1 WO2011090125 A1 WO 2011090125A1
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Prior art keywords
light
control plate
light control
axis
light source
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PCT/JP2011/050999
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French (fr)
Japanese (ja)
Inventor
武志 川上
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住友化学株式会社
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    • 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
    • G02B5/0215—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 a regular structure

Definitions

  • the present invention relates to a light control plate, a surface light source device, and a transmissive image display device.
  • a direct type surface light source device is used as an example of a light source that outputs a backlight of a liquid crystal display unit.
  • a typical surface light source device a device in which a plurality of light sources are arranged on the back side of a light control plate such as a light diffusion plate is used.
  • the luminance of the light emitting surface can be easily increased by increasing the number of light sources to be arranged.
  • the distance between the light source and the light control plate is shortened, there is a problem that the luminance uniformity is lowered.
  • the periodic brightness non-uniformity that occurs because the brightness near the light source is high is a problem. Due to the reduction in the number of light sources for reducing the thickness of the surface light source device or reducing the power consumption, the periodic luminance non-uniformity has become a greater problem.
  • Patent Document 1 a light amount correction pattern is formed on a light diffusion plate as an example of a light control plate corresponding to the distance between the light source and the light diffusion plate. ing.
  • Patent Document 2 by providing a prism with a sawtooth cross section in a part of the surface of the light diffusing plate that faces the light source, just above the light source, light near the light source with a large amount of light is scattered. ing.
  • an object of the present invention is to provide a light control plate, a surface light source device, and a transmissive image display device that can suppress uneven brightness more stably.
  • the light control plate according to the present invention is a light control plate that emits light incident from the first surface from a second surface located on the opposite side of the first surface.
  • the light control plate according to the present invention includes a plurality of convex portions formed on the second surface.
  • Each of the plurality of convex portions extends in the first direction, and the plurality of convex portions are arranged in parallel in a second direction orthogonal to the first direction.
  • an axis passing through both ends of each convex portion with respect to the second direction is an x-axis, and the center of both ends on the x-axis is passed.
  • each convex portion in the cross section is ⁇ 0.475 w a ⁇ x ⁇ 0. in .475w a, represented by z (x) satisfying the equation (1).
  • z 0 (x) satisfies Formula (2).
  • h a is a number of 0.56 w a or more and less than 0.58 w a
  • k a is a number of ⁇ 0.039 or more and less than ⁇ 0.027.
  • the convex portion has a cross-sectional shape represented by z (x), it is possible to more stably reduce uneven brightness of light emitted from the light control plate.
  • the light control plate according to the present invention may be made of a transparent material, and the refractive index of each convex portion may be 1.50 or more and less than 1.52.
  • the surface light source device includes a light control plate according to the present invention and a plurality of light sources that are arranged apart from each other and supply light to the first surface of the light control plate.
  • the surface light source device includes the light control plate according to the present invention, it is possible to more stably reduce non-uniform luminance of emitted light.
  • a transmissive image display device includes a light control plate according to the present invention, a plurality of light sources that are spaced apart from each other and supply light to the first surface of the light control plate, and the light control plate A transmissive image display unit that is illuminated by light emitted from the second surface and displays an image.
  • the transmissive image display device includes the light control plate according to the present invention, it is possible to stably illuminate the transmissive image display unit with light in which uneven luminance is suppressed. Therefore, it is possible to stably display an image without uneven brightness.
  • a light control plate that can more stably suppress uneven luminance, a surface light source device including the light control plate, and a transmissive image display device.
  • FIG. 1 is a cross-sectional view schematically showing a configuration of an embodiment of a transmissive image display device according to the present invention.
  • FIG. 2 is a cross-sectional view of a light diffusing plate used in the transmissive image display apparatus shown in FIG.
  • FIG. 3 is a drawing showing a cross-sectional shape of an example of the convex portion of the light diffusion plate.
  • FIG. 4 is a diagram illustrating conditions that are satisfied by a contour line indicating the cross-sectional shape of the convex portion illustrated in FIG. 3.
  • FIG. 5 is a diagram for explaining an example of a contour line of a convex portion and a condition to be satisfied by the contour line.
  • FIG. 6 is a cross-sectional view showing another example of the light diffusing plate.
  • FIG. 1 is a cross-sectional view schematically showing a configuration of an embodiment of a transmissive image display device according to the present invention.
  • FIG. 1 is an exploded view of a transmissive image display device.
  • FIG. 2 is a cross-sectional view of a light diffusing plate included in the surface light source device included in the transmissive image display device shown in FIG. In FIG. 2, two adjacent light sources are also schematically shown for convenience of explanation.
  • the transmissive image display device 1 includes a transmissive image display unit 10 and a surface light source device 20 that supplies a backlight to the transmissive image display unit 10.
  • An example of the transmissive image display unit 10 is a liquid crystal display panel in which linear polarizing plates 12 and 13 are disposed on both surfaces of a liquid crystal cell 11, for example.
  • the transmissive image display device 1 is a liquid crystal display device (or a liquid crystal television).
  • the liquid crystal cell 11 and the polarizing plates 12 and 13 those used in a transmissive image display device such as a conventional liquid crystal display device can be used.
  • An example of the liquid crystal cell 11 is a known liquid crystal cell such as a TFT liquid crystal cell or an STN liquid crystal cell.
  • the surface light source device 20 is a so-called direct type surface light source device.
  • the surface light source device 20 includes a light source unit 30 including a plurality of light sources 31.
  • the plurality of light sources 31 are arranged in parallel.
  • Each light source 31 is a linear light source extending in a direction orthogonal to the arrangement direction of the plurality of light sources 31.
  • An example of each light source 31 is a straight tubular light source such as a fluorescent lamp (cold cathode ray lamp).
  • the plurality of light sources 31 are arranged at intervals so that the central axes of the light sources 31 are located in the same plane P.
  • the distance between the central axes of two adjacent light sources 31 among the plurality of light sources 31 is L
  • an example of the distance L is 10 mm to 150 mm.
  • the light source 31 has been described as being linear.
  • the light source 31 may be a point light source such as an LED.
  • the plane P shown in FIG. 1 is a virtual plane for convenience of explanation.
  • the plurality of light sources 31 are preferably arranged in the lamp box 32 as shown in FIG.
  • the inner surface 32a of the lamp box 32 is preferably formed as a light reflecting surface. This is because the light output from each light source 31 is reliably output to the transmissive image display unit 10 side, so that the light from each light source 31 can be used efficiently.
  • the light source unit 30 will be described as including the lamp box 32 having the above-described preferable configuration.
  • the surface light source device 20 is a light diffusing plate as a light control plate disposed on the front side (upper side in FIG. 1) of the light source unit 30, that is, on the transmissive image display unit 10 side and spaced from the light source 31. 40.
  • the distance between the light diffusion plate 40 and the plurality of light sources 31 is D
  • an example of the distance D is 3 mm to 50 mm.
  • the distance between the two adjacent light sources 31, 31 is set so that L / D is 2 or more, preferably L / D is 2.5 or more. L and the separation distance D are selected.
  • the light diffusing plate 40 does not project the image of each light source 31 onto the transmissive image display unit 10, and is reflected by the light from the light source unit 30, that is, the direct light from each light source 31 and the inner surface 32 a of the lamp box 32. This is for irradiating the reflected light while diffusing it toward the transmissive image display unit 10.
  • the thickness d of the light diffusing plate 40 is usually 0.1 mm to 5 mm.
  • the light diffusing plate 40 may be a film or a sheet.
  • the light diffusion plate 40 is made of a transparent material.
  • the transparent material are transparent resin and transparent glass.
  • An example of the refractive index of the transparent material is 1.50 or more and less than 1.52.
  • the transparent resin include a modified norbornene resin, polyacrylonitrile resin, MS resin (methyl methacrylate-styrene copolymer resin, styrene ratio: 10% to 30%).
  • additives such as an ultraviolet absorber, an antistatic agent, an antioxidant, a processing stabilizer, a flame retardant, and a lubricant can be added to the transparent resin material. These additives can be used alone or in combination of two or more.
  • UV absorbers examples include benzotriazole UV absorbers, benzophenone UV absorbers, cyanoacrylate UV absorbers, malonic ester UV absorbers, oxalic anilide UV absorbers, and triazine UV absorbers. is there.
  • the ultraviolet absorber are a benzotriazole ultraviolet absorber and a triazine ultraviolet absorber.
  • a transparent resin material is usually used without adding a light diffusing agent as an additive.
  • a light diffusing agent may be added and used.
  • the light diffusing plate 40 may be coated with an antistatic agent on one side or both sides.
  • an antistatic agent By applying an antistatic agent, dust adhesion due to static electricity can be prevented, and a decrease in light transmittance due to dust adhesion can be prevented.
  • the light diffusing plate 40 has a substantially flat first surface 40a on the light source unit 30 side and a second surface 40b on the transmissive image display unit 10 side. A plurality of convex portions 41 are formed on the second surface 40b. In the light diffusing plate 40 in which the convex portion 41 is formed, the thickness d of the light diffusing plate 40 can be a distance between the top of the convex portion 41 and the first surface 40a.
  • each convex portion 41 is a linear optical element extending in one direction (first direction).
  • optical elements are lenses and prisms.
  • the plurality of convex portions 41 are arranged in parallel in a direction (second direction) substantially orthogonal to the extending direction of the convex portions 41.
  • the plurality of convex portions 41 are formed on the entire surface of the second surface 40b.
  • the ends 41 a in the cross-sectional shape of the adjacent convex portions 41 overlap in the arrangement direction of the convex portions 41.
  • each convex portion 41 is substantially the same among the plurality of convex portions 41.
  • the separation distance D and the distance L are selected so that L / D, which is the ratio of the separation distance D and the distance L between the two adjacent light sources 31, 31, is 2 or more, preferably 2.5 or more. This is as described above.
  • FIG. 3 is a drawing showing an example of a cross-sectional shape orthogonal to the extending direction of the convex portion, and shows an enlarged one convex portion.
  • the cross-sectional shape of the convex portion 41 will be described using a local xz coordinate system set as shown in FIG.
  • the x-axis constituting the xz coordinate system is parallel to the arrangement direction (second direction) of the plurality of convex portions 41, and the z-axis is parallel to the plate thickness direction (direction orthogonal to the first and second directions). It is.
  • the cross-sectional shape of the convex portion 41 is represented by z (x) that satisfies Expression (3).
  • z 0 (x) satisfies Formula (4).
  • w a is the length of the convex portion 41 in the x-axis direction.
  • h a is a constant selected from the range of 0.56 w a ⁇ h a ⁇ 0.58 w a .
  • k a is a constant selected from the range of ⁇ 0.039 ⁇ k a ⁇ 0.027.
  • h a corresponds to the maximum height in the z-axis direction between both ends 41a and 41a of the convex portion 41 when the convex portion 41 has a shape represented by z 0 (x).
  • FIG. 3 illustrates a shape in which z 0 (x) is expanded and contracted by a predetermined multiple (for example, one time) in the z direction within a range satisfying the expression (3).
  • both ends 41a and 41a are located on the x-axis
  • the top 41b is located on the z-axis.
  • the convex portion 41 has a contour line that is symmetric with respect to the z-axis.
  • the contour line of the convex portion 41 is not limited to a shape in which z 0 (x) is expanded and contracted by a predetermined time (for example, 1 time) in the z direction.
  • the outline of the convex part 41 should just satisfy
  • z (x) is an outline represented by 0.95z 0 (x) when z 0 (x) is determined for a certain width w a as shown in FIG. 1.05z 0 (x), any contour line passing through the region between the contour lines may be used.
  • Width w a of the convex portion 41 since formation of the convex portion 41 is easy, usually 40 ⁇ m or more, preferably 80 ⁇ m or more, since the pattern due to the convex portion 41 is hardly visible to the naked eye Usually, it is 800 ⁇ m or less, preferably 450 ⁇ m or less. Specific examples of width w a is, 410 ⁇ m, 400 ⁇ m, 325 ⁇ m, a 280 ⁇ m and 100 [mu] m. However, the value of w a is not limited to this.
  • FIG. 5 is a drawing showing an example of the contour line of the convex portion and the conditions that the contour line of the convex portion should satisfy.
  • the horizontal axis in FIG. 5 indicates the position ( ⁇ m), and the vertical axis indicates the height ( ⁇ m).
  • w a 100 ⁇ m
  • h a 0.57 w a
  • k a ⁇ 0.033.
  • Z 0 (x) determined by these numerical values is referred to as z1 0 (x) for convenience.
  • w a 100 ⁇ m, but it is not limited to this, as described above.
  • the cross-sectional shape of the convex portion 41 is represented by z (x) that satisfies Expression (3).
  • the cross-sectional shape of the convex portion 41 may be expressed by z (x) that satisfies the expression (3) when ⁇ 0.475 w a ⁇ x ⁇ 0.475 w a . This is because the molding error tends to be relatively large in the vicinity of the bottom of the convex portion 41 (in the vicinity of the end), but the shape of the vicinity of the bottom has little influence on the light diffusibility.
  • the light diffusing plate 40 shown in FIG. 2 When the light diffusing plate 40 shown in FIG. 2 is applied to the transmissive image display device 1, the light diffusing plate 40 is arranged such that the extending direction (first direction) of the convex portion 41 is the horizontal direction of the screen. You may arrange
  • the light diffusing plate 40 can be manufactured by designing the cross-sectional shape of the convex portion 41 so as to satisfy Equation (3) and, for example, by cutting out from a transparent material.
  • the light diffusing plate 40 can be manufactured by a method such as an injection molding method, an extrusion molding method, a press molding method, or a photopolymer method.
  • the light output from each light source 31 of the light source unit 30 is reflected directly or by the inner surface 32 a of the lamp box 32 to the light diffusing plate 40. Incident.
  • the light incident on the light diffusing plate 40 is irradiated from the second surface 40b toward the transmissive image display unit 10. Since a plurality of convex portions 41 are formed on the second surface 40 b, light is emitted through the convex portions 41. As a result, planar light is generated by the light diffusion plate 40.
  • the convex portion 41 has a cross-sectional shape represented by z (x), it is possible to suppress nonuniform luminance.
  • the L / D is a predetermined value (deformation due to displacement of the light diffusion plate 40 with respect to the light source 31 or heat). For example, even if it fluctuates from the design value), non-uniform luminance is less likely to occur, and the non-uniform luminance can be suppressed more stably.
  • the point that the light diffusing plate 40 can suppress non-uniformity in luminance and can further stably suppress non-uniform luminance will be specifically described with reference to simulation results.
  • the simulation was performed in a configuration in which a light diffusion plate 40 is disposed on a plurality of light sources 31 as shown in FIG.
  • the refractive index of the light diffusing plate 40 was 1.51 including the convex portion 41.
  • the light emitted from the light diffusing plate 40 was obtained by the ray tracing method, and the luminance uniformity (%) in the plane orthogonal to the z direction was calculated.
  • the brightness uniformity (%) was calculated by “(lowest brightness / highest brightness) ⁇ 100”.
  • z 0 (x) h a and k a are included in the the case of the above-described range (i.e., 0.56w a ⁇ h a ⁇ 0.58w a and -0.039 ⁇ k a ⁇ -0.027)
  • a case outside the above range will be described as a comparative example.
  • Example 1 achieves a brightness uniformity of 88.4%.
  • the conditions of Example 1, Comparative Example 1, and Comparative Example 2 other than the cross-sectional shape of the convex portion 41 are the same. Therefore, by setting the cross-sectional shape of the convex portion 41 to the shape of Example 1, it is possible to obtain a higher luminance uniformity than Comparative Example 1 and Comparative Example 2.
  • Example 2 a simulation was performed under the condition that L / D was changed from Example 1.
  • the simulation of Example 2 was performed under the same conditions as in Example 1 except that the distance D between the light source 31 and the light diffusion plate 40 was 14 mm.
  • L / D 2.14.
  • Example 2 achieves a brightness uniformity of 83.6%. That is, by having the convex portion 41 represented by z (x) whose cross-sectional shape satisfies the expression (3), the light diffusion plate 40 has an L / D that varies from a predetermined value (for example, a design value). However, non-uniform luminance is less likely to occur, and the non-uniform luminance can be suppressed more stably.
  • the surface light source device 20 including the light diffusing plate 40 can output light in which unevenness in luminance is suppressed.
  • the transmissive image display device 1 including the light diffusing plate 40 the transmissive image display unit 10 can be illuminated by light with suppressed luminance non-uniformity. Therefore, the transmissive image display device 1 can improve display quality. Can do. Even the surface light source device 20 including the light diffusing plate 40 can more stably output light in which nonuniform luminance is suppressed.
  • the transmissive image display device 1 including the light diffusing plate 40 it is possible to suppress a change in display quality due to a displacement of the light diffusing plate 40 with respect to the light source 31 or deformation due to heat or the like while improving display quality.
  • the light control plate may be an optical component that adjusts the luminance uniformity of light output from a plurality of light sources in a plane parallel to a plane on which the plurality of light sources are arranged.
  • the light control plate may be a brightness adjusting plate such as an optical sheet such as a prism sheet or a lens sheet or an optical film having a plurality of the convex portions described above on the light emission side of a plate made of a transparent material.
  • the light diffusion plate 40 may be a single layer plate made of a single transparent material.
  • the light diffusing plate 40 may be a multilayer plate having a structure in which layers made of different transparent materials are laminated.
  • FIG. 6 is a cross-sectional view of an example of a light diffusion plate in the case of a multilayer plate.
  • the light diffusing plate 50 as a multilayer plate includes a skin layer 51, a base portion 52 provided on the skin layer 51, and a convex portion forming layer 53 provided on the base portion 52.
  • the convex portion forming layer 53 is a shape imparting layer configured by arranging a plurality of convex portions 41 in a direction orthogonal to the extending direction of the convex portions 41.
  • the shape of the convex portion 41 is the same as that shown in FIG.
  • Each convex portion 41 included in the convex portion forming layer 53 is made of a transparent material.
  • the refractive index of each convex part 41 can be 1.50 or more and less than 1.52.
  • the base portion 52 is a plate-like body made of a transparent material.
  • the refractive index of the base portion 52 can be 1.50 or more and less than 1.52.
  • the refractive index of the base portion 52 may be different from the refractive index of the convex portion 41.
  • the refractive index of the base portion 52 is preferably the same as the refractive index of the convex portion 41.
  • the skin layer 51 is also a plate-like body made of a transparent material.
  • the surface of the skin layer 51 opposite to the base portion 52 is flat.
  • the skin layer 51 is thinner than the base portion 52.
  • An example of the thickness of the skin layer 51 is 10 ⁇ m or more and less than 100 ⁇ m.
  • the skin layer 51 may have a refractive index difference of 0.1 or less with respect to the base portion 52.
  • the refractive index of the skin layer 51 is preferably the same as that of the base portion 52.
  • the skin layer 51 preferably contains an ultraviolet absorber. This is because, when the skin layer 51 contains the ultraviolet absorber, for example, when the light source 31 including ultraviolet rays is used as output light like a fluorescent tube, deterioration of the light diffusion plate due to the ultraviolet rays from the light source 31 can be prevented. Moreover, when the base
  • the plurality of light sources 31 included in the light source unit 30 are arranged at substantially equal intervals with the interval L.
  • the distance between the two adjacent light sources 31 may be different.
  • SYMBOLS 1 Transmission type image display apparatus, 10 ... Transmission type image display part, 20 ... Surface light source device, 30 ... Light source part, 31 ... Light source, 40 ... Light diffusing plate (light control board), 40a ... 1st surface, 40b ... 2nd surface, 41 ... convex part, 41a ... end of convex part, 41b ... top part of convex part.

Abstract

A light control plate (40) emits, from a second surface (40b), the light that entered from a first surface (40a). The light control plate is provided with a plurality of projected parts (41) on the second surface. The projected parts extend in a first direction and are disposed in parallel in a second direction which is orthogonal to the first direction. With respect to the cross-sectional surface which is orthogonal to the first direction of the projected parts, the shape of the outline of the projected parts in the cross-sectional surface is represented by z(x) which fulfills the formula 0.95×z0(x)≤z(x)≤1.05×z0(x) in a range of -0.475wa≤x≤0.475wa, wherein the x axis represents the axis which passes through both ends of the projected parts in relation to the second direction, and the z axis represents the axis which passes through the center of both ends in relation to the x axis and which is orthogonal to the x axis. (z0(x) is represented by the subsequent formula.) As a consequence, a light control plate, surface light source device, and transmission-type image display device, in which it is possible to stably prevent the brightness from becoming uneven, can be provided. (wa represents the length of the projected parts in the x axis direction, ha has a range of 0.56wa≤ha<0.58wa, and ka has a range of -0.039≤ka<-0.027.)

Description

光制御板、面光源装置及び透過型画像表示装置Light control plate, surface light source device, and transmissive image display device
　本発明は、光制御板、面光源装置及び透過型画像表示装置に関する。 The present invention relates to a light control plate, a surface light source device, and a transmissive image display device.
　液晶表示装置などの透過型画像表示装置では、液晶表示部のバックライトを出力する光源の一例として直下型面光源装置が使用されている。典型的な面光源装置として、光拡散板といった光制御板の背面側に複数の光源を並べたものが利用されている。このような面光源装置では、配置する光源数を増やすことにより発光面を容易に高輝度化できる。しかしながら、光源と光制御板との距離を短くすると輝度均斉度が低くなるという問題点を有する。特に、光源の真上付近での輝度が高くなるために発生する周期的な輝度の不均一が問題である。面光源装置の薄型化、或いは低消費電力化のための光源数が削減されることによって上記周期的な輝度の不均一がより大きな問題となってきている。 In a transmissive image display device such as a liquid crystal display device, a direct type surface light source device is used as an example of a light source that outputs a backlight of a liquid crystal display unit. As a typical surface light source device, a device in which a plurality of light sources are arranged on the back side of a light control plate such as a light diffusion plate is used. In such a surface light source device, the luminance of the light emitting surface can be easily increased by increasing the number of light sources to be arranged. However, when the distance between the light source and the light control plate is shortened, there is a problem that the luminance uniformity is lowered. In particular, the periodic brightness non-uniformity that occurs because the brightness near the light source is high is a problem. Due to the reduction in the number of light sources for reducing the thickness of the surface light source device or reducing the power consumption, the periodic luminance non-uniformity has become a greater problem.
　そこで、輝度均斉度を確保するために、例えば、特許文献１では、光制御板の一例としての光拡散板に、光源と光拡散板との間の距離に対応して光量補正パターンを形成している。同様に、特許文献２では、光拡散板の光源に面する面の光源の真上付近の一部に断面が鋸歯状のプリズムを設けることで、光量の多い光源の真上付近の光を散らしている。 Therefore, in order to ensure the luminance uniformity, for example, in Patent Document 1, a light amount correction pattern is formed on a light diffusion plate as an example of a light control plate corresponding to the distance between the light source and the light diffusion plate. ing. Similarly, in Patent Document 2, by providing a prism with a sawtooth cross section in a part of the surface of the light diffusing plate that faces the light source, just above the light source, light near the light source with a large amount of light is scattered. ing.
特開平６－２７３７６０号公報JP-A-6-273760 特開２００４－１２７６８０号公報JP 2004-127680 A
　しかし、特許文献１の光量補正パターン及び特許文献２の断面が鋸歯状のプリズムのように、光源の位置と光制御板との間の距離に依存関係を持たせたバックライトの構成では、光制御板の位置ずれや、熱による変形などによって、輝度均斉度が悪化する。 However, in the configuration of the backlight in which the light amount correction pattern of Patent Document 1 and the cross section of Patent Document 2 have a dependency relationship with the distance between the position of the light source and the light control plate, such as a sawtooth prism, The brightness uniformity deteriorates due to the displacement of the control plate or deformation due to heat.
　そこで、本発明は、より安定して輝度の不均一を抑制可能な光制御板、面光源装置及び透過型画像表示装置を提供することを目的とする。 Therefore, an object of the present invention is to provide a light control plate, a surface light source device, and a transmissive image display device that can suppress uneven brightness more stably.
　本発明に係る光制御板は、第１の面から入射した光を第１の面と反対側に位置する第２の面から出射する光制御板である。本発明に係る光制御板は、第２の面に形成される複数の凸状部を備える。複数の凸状部の各々は、第１の方向に延在しており、複数の凸状部は、第１の方向に直交する第２の方向に並列配置されている。また、複数の凸状部の各々の第１の方向に直交する断面において、前記第２の方向に対する各凸状部の両端をとおる軸をｘ軸とし、ｘ軸上において上記両端の中心をとおりｘ軸に直交する軸をｚ軸とし、各凸状部のｘ軸方向の長さをｗａとしたとき、上記断面における各凸状部の輪郭形状は、－０．４７５ｗａ≦ｘ≦０．４７５ｗａにおいて、式（１）を満たすｚ（ｘ）で表される。
Figure JPOXMLDOC01-appb-M000003
 　ただし、式（１）において、ｚ０（ｘ）は式（２）を満たす。
Figure JPOXMLDOC01-appb-M000004
 式(２)中、ｈａは０．５６ｗａ以上且つ０．５８ｗａ未満の数であり、ｋａは－０．０３９以上且つ－０．０２７未満の数である。 The light control plate according to the present invention is a light control plate that emits light incident from the first surface from a second surface located on the opposite side of the first surface. The light control plate according to the present invention includes a plurality of convex portions formed on the second surface. Each of the plurality of convex portions extends in the first direction, and the plurality of convex portions are arranged in parallel in a second direction orthogonal to the first direction. Further, in a cross section orthogonal to the first direction of each of the plurality of convex portions, an axis passing through both ends of each convex portion with respect to the second direction is an x-axis, and the center of both ends on the x-axis is passed. When the axis perpendicular to the x-axis is the z-axis and the length of each convex portion in the x-axis direction is w a , the contour shape of each convex portion in the cross section is −0.475 w a ≦ x ≦ 0. in .475w a, represented by z (x) satisfying the equation (1).
Figure JPOXMLDOC01-appb-M000003
 However, in Formula (1), z 0 (x) satisfies Formula (2).
Figure JPOXMLDOC01-appb-M000004
 In the formula (2), h a is a number of 0.56 w a or more and less than 0.58 w a , and k a is a number of −0.039 or more and less than −0.027.
　上記構成の光制御板では、凸状部が上記ｚ（ｘ）で表される断面形状を有することから、光制御板から出射される光の輝度の不均一をより安定して低減できる。 In the light control plate having the above configuration, since the convex portion has a cross-sectional shape represented by z (x), it is possible to more stably reduce uneven brightness of light emitted from the light control plate.
　本発明に係る光制御板は、透明材料からなり、各凸状部の屈折率は１．５０以上且つ１．５２未満である、とすることができる。 The light control plate according to the present invention may be made of a transparent material, and the refractive index of each convex portion may be 1.50 or more and less than 1.52.
　本発明に係る面光源装置は、本発明に係る光制御板と、互いに離間して配置されており、光制御板の第１の面に光を供給する複数の光源と、を備える。 The surface light source device according to the present invention includes a light control plate according to the present invention and a plurality of light sources that are arranged apart from each other and supply light to the first surface of the light control plate.
　本発明に係る面光源装置は、本発明に係る光制御板を備えているので、出射される光の輝度の不均一をより安定して低減できる。 Since the surface light source device according to the present invention includes the light control plate according to the present invention, it is possible to more stably reduce non-uniform luminance of emitted light.
　本発明に係る透過型画像表示装置は、本発明に係る光制御板と、互いに離間して配置されており、光制御板の第１の面に光を供給する複数の光源と、光制御板の第２の面から出射される光によって照明され画像を表示する透過型画像表示部と、を備える。 A transmissive image display device according to the present invention includes a light control plate according to the present invention, a plurality of light sources that are spaced apart from each other and supply light to the first surface of the light control plate, and the light control plate A transmissive image display unit that is illuminated by light emitted from the second surface and displays an image.
　本発明に係る透過型画像表示装置では、本発明に係る光制御板を備えているので、安定して輝度の不均一の抑制された光で透過型画像表示部を照明することができる。よって、輝度の不均一のない画像を安定して表示可能である。 Since the transmissive image display device according to the present invention includes the light control plate according to the present invention, it is possible to stably illuminate the transmissive image display unit with light in which uneven luminance is suppressed. Therefore, it is possible to stably display an image without uneven brightness.
　本発明によれば、より安定して輝度の不均一を抑制可能な光制御板並びにその光制御板を含む面光源装置及び透過型画像表示装置を提供することができる。 According to the present invention, it is possible to provide a light control plate that can more stably suppress uneven luminance, a surface light source device including the light control plate, and a transmissive image display device.
図１は、本発明に係る透過型画像表示装置の一実施形態の構成を模式的に示す断面図である。FIG. 1 is a cross-sectional view schematically showing a configuration of an embodiment of a transmissive image display device according to the present invention. 図２は、図１に示した透過型画像表示装置に用いられる光拡散板の断面図である。FIG. 2 is a cross-sectional view of a light diffusing plate used in the transmissive image display apparatus shown in FIG. 図３は、光拡散板が有する凸状部の一例の断面形状を示す図面である。FIG. 3 is a drawing showing a cross-sectional shape of an example of the convex portion of the light diffusion plate. 図４は、図３に示す凸状部の断面形状を示す輪郭線が満たす条件を示す図面である。FIG. 4 is a diagram illustrating conditions that are satisfied by a contour line indicating the cross-sectional shape of the convex portion illustrated in FIG. 3. 図５は、凸状部の輪郭線の一例及びその輪郭線が満たすべき条件を説明する図面である。FIG. 5 is a diagram for explaining an example of a contour line of a convex portion and a condition to be satisfied by the contour line. 図６は、光拡散板の他の例を示す断面図である。FIG. 6 is a cross-sectional view showing another example of the light diffusing plate.
　以下、図面を参照して本発明の光制御板、面光源装置及び透過型画像表示装置の実施形態について説明する。図面の説明においては同一要素には同一符号を付し、重複する説明を省略する。図面の寸法比率は、説明のものと必ずしも一致していない。 Hereinafter, embodiments of a light control plate, a surface light source device, and a transmissive image display device of the present invention will be described with reference to the drawings. In the description of the drawings, the same reference numerals are given to the same elements, and duplicate descriptions are omitted. The dimensional ratios in the drawings do not necessarily match those described.
　図１は、本発明に係る透過型画像表示装置の一実施形態の構成を模式的に示す断面図である。図１は、透過型画像表示装置を分解して示している。図２は、図１に示した透過型画像表示装置に含まれる面光源装置が有する光拡散板の断面図である。図２では、説明の便宜のため、隣接する２つの光源も模式的に示している。 FIG. 1 is a cross-sectional view schematically showing a configuration of an embodiment of a transmissive image display device according to the present invention. FIG. 1 is an exploded view of a transmissive image display device. FIG. 2 is a cross-sectional view of a light diffusing plate included in the surface light source device included in the transmissive image display device shown in FIG. In FIG. 2, two adjacent light sources are also schematically shown for convenience of explanation.
　透過型画像表示装置１は、透過型画像表示部１０と、透過型画像表示部１０にバックライトを供給する面光源装置２０とを備える。透過型画像表示部１０の例は、例えば液晶セル１１の両面に直線偏光板１２，１３が配置された液晶表示パネルである。この場合、透過型画像表示装置１は液晶表示装置（又は液晶テレビ）である。液晶セル１１，偏光板１２，１３は、従来の液晶表示装置等の透過型画像表示装置で用いられているものを用いることができる。液晶セル１１の例は、ＴＦＴ型の液晶セル、ＳＴＮ型の液晶セル等の公知の液晶セルである。 The transmissive image display device 1 includes a transmissive image display unit 10 and a surface light source device 20 that supplies a backlight to the transmissive image display unit 10. An example of the transmissive image display unit 10 is a liquid crystal display panel in which linear polarizing plates 12 and 13 are disposed on both surfaces of a liquid crystal cell 11, for example. In this case, the transmissive image display device 1 is a liquid crystal display device (or a liquid crystal television). As the liquid crystal cell 11 and the polarizing plates 12 and 13, those used in a transmissive image display device such as a conventional liquid crystal display device can be used. An example of the liquid crystal cell 11 is a known liquid crystal cell such as a TFT liquid crystal cell or an STN liquid crystal cell.
　面光源装置２０は、いわゆる直下型の面光源装置である。面光源装置２０は、複数の光源３１を含む光源部３０を有する。複数の光源３１は、並列配置されている。各光源３１は、複数の光源３１の配列方向に直交する方向に延在している線状光源である。各光源３１の例は蛍光ランプ（冷陰極線ランプ）のような直管状の光源である。複数の光源３１は各光源３１の中心軸線が同一の平面Ｐ内に位置するように間隔をあけて配置されている。複数の光源３１のうちの、隣接する２つの光源３１，３１の中心軸線間の距離をＬとした場合、距離Ｌの例は１０ｍｍ～１５０ｍｍである。ここでは、光源３１は線状として説明した。しかしながら、光源３１は、ＬＥＤのような点状光源などを用いることも可能である。図１中に示した平面Ｐは説明の便宜のためであり、仮想的な平面である。 The surface light source device 20 is a so-called direct type surface light source device. The surface light source device 20 includes a light source unit 30 including a plurality of light sources 31. The plurality of light sources 31 are arranged in parallel. Each light source 31 is a linear light source extending in a direction orthogonal to the arrangement direction of the plurality of light sources 31. An example of each light source 31 is a straight tubular light source such as a fluorescent lamp (cold cathode ray lamp). The plurality of light sources 31 are arranged at intervals so that the central axes of the light sources 31 are located in the same plane P. When the distance between the central axes of two adjacent light sources 31 among the plurality of light sources 31 is L, an example of the distance L is 10 mm to 150 mm. Here, the light source 31 has been described as being linear. However, the light source 31 may be a point light source such as an LED. The plane P shown in FIG. 1 is a virtual plane for convenience of explanation.
　複数の光源３１は、図１に示すように、ランプボックス３２内に配置されていることが好ましい。ランプボックス３２の内面３２ａは、光反射面として形成されていることが好ましい。これにより、各光源３１から出力された光が透過型画像表示部１０側に確実に出力されるため、各光源３１からの光を効率的に利用することが可能となるからである。本実施形態では、光源部３０は、上記好ましい構成のランプボックス３２を有するものとして説明する。 The plurality of light sources 31 are preferably arranged in the lamp box 32 as shown in FIG. The inner surface 32a of the lamp box 32 is preferably formed as a light reflecting surface. This is because the light output from each light source 31 is reliably output to the transmissive image display unit 10 side, so that the light from each light source 31 can be used efficiently. In the present embodiment, the light source unit 30 will be described as including the lamp box 32 having the above-described preferable configuration.
　面光源装置２０は、光源部３０の前面側（図１中、上側）、すなわち、透過型画像表示部１０側に、光源３１に対して離間して配置された光制御板としての光拡散板４０を有している。後述するように、上記光拡散板４０と複数の光源３１との間の離間距離をＤとした場合、離間距離Ｄの例は、３ｍｍ～５０ｍｍである。面光源装置２０では、薄型化を図るため、Ｌ／Ｄが２以上となるように、好ましくは、Ｌ／Ｄが２．５以上となるように、隣接する２つの光源３１，３１間の距離Ｌ及び離間距離Ｄが選択されている。 The surface light source device 20 is a light diffusing plate as a light control plate disposed on the front side (upper side in FIG. 1) of the light source unit 30, that is, on the transmissive image display unit 10 side and spaced from the light source 31. 40. As will be described later, when the distance between the light diffusion plate 40 and the plurality of light sources 31 is D, an example of the distance D is 3 mm to 50 mm. In the surface light source device 20, in order to reduce the thickness, the distance between the two adjacent light sources 31, 31 is set so that L / D is 2 or more, preferably L / D is 2.5 or more. L and the separation distance D are selected.
　光拡散板４０は、各光源３１の像を透過型画像表示部１０に投影しないために、光源部３０からの光、すなわち、各光源３１からの直接光及びランプボックス３２の内面３２ａで反射した反射光を透過型画像表示部１０に向けて拡散させつつ照射するためのものである。光拡散板４０の厚さｄは、通常は０．１ｍｍ～５ｍｍである。光拡散板４０は、フィルム状であってもよいし、シート状であってもよい。 The light diffusing plate 40 does not project the image of each light source 31 onto the transmissive image display unit 10, and is reflected by the light from the light source unit 30, that is, the direct light from each light source 31 and the inner surface 32 a of the lamp box 32. This is for irradiating the reflected light while diffusing it toward the transmissive image display unit 10. The thickness d of the light diffusing plate 40 is usually 0.1 mm to 5 mm. The light diffusing plate 40 may be a film or a sheet.
　光拡散板４０は透明材料からなる。透明材料の例は、透明樹脂、透明ガラスである。透明材料の屈折率の例は、１．５０以上且つ１．５２未満である。また、透明樹脂の例は、変性ノルボルネン樹脂、ポリアクリロニトリル樹脂、ＭＳ樹脂（メタクリル酸メチル－スチレン共重合体樹脂、スチレンの割合：１０％～３０％）などである。 The light diffusion plate 40 is made of a transparent material. Examples of the transparent material are transparent resin and transparent glass. An example of the refractive index of the transparent material is 1.50 or more and less than 1.52. Examples of the transparent resin include a modified norbornene resin, polyacrylonitrile resin, MS resin (methyl methacrylate-styrene copolymer resin, styrene ratio: 10% to 30%).
　透明材料として透明樹脂材料を用いる場合、透明樹脂材料に紫外線吸収剤、帯電防止剤、酸化防止剤、加工安定剤、難燃剤、滑剤などの添加剤を添加することもできる。これらの添加剤はそれぞれ単独で、または２種以上を組み合わせて用いることができる。 When a transparent resin material is used as the transparent material, additives such as an ultraviolet absorber, an antistatic agent, an antioxidant, a processing stabilizer, a flame retardant, and a lubricant can be added to the transparent resin material. These additives can be used alone or in combination of two or more.
　紫外線吸収剤の例は、ベンゾトリアゾール系紫外線吸収剤、ベンゾフェノン系紫外線吸収剤、シアノアクリレート系紫外線吸収剤、マロン酸エステル系紫外線吸収剤、シュウ酸アニリド系紫外線吸収剤、トリアジン系紫外線吸収剤などである。紫外線吸収剤の好ましい例はベンゾトリアゾール系紫外線吸収剤、トリアジン系紫外線吸収剤である。 Examples of UV absorbers include benzotriazole UV absorbers, benzophenone UV absorbers, cyanoacrylate UV absorbers, malonic ester UV absorbers, oxalic anilide UV absorbers, and triazine UV absorbers. is there. Preferable examples of the ultraviolet absorber are a benzotriazole ultraviolet absorber and a triazine ultraviolet absorber.
　透明樹脂材料は通常、添加剤として光拡散剤を添加することなく用いられる。しかしながら、本発明の目的を著しく損なわない量であれば、光拡散剤を添加して用いてもよい。 A transparent resin material is usually used without adding a light diffusing agent as an additive. However, as long as the object of the present invention is not significantly impaired, a light diffusing agent may be added and used.
　光拡散板４０には、片面または両面に帯電防止剤が塗布されていてもよい。帯電防止剤を塗布することにより、静電気によるホコリの付着などを防止して、ホコリの付着による光線透過率の低下を防止することができる。 The light diffusing plate 40 may be coated with an antistatic agent on one side or both sides. By applying an antistatic agent, dust adhesion due to static electricity can be prevented, and a decrease in light transmittance due to dust adhesion can be prevented.
　図１及び図２に示すように、光拡散板４０は、光源部３０側にほぼ平坦な第１の面４０ａを有すると共に、透過型画像表示部１０側に第２の面４０ｂを有する。第２の面４０ｂには、複数の凸状部４１が形成されている。凸状部４１が形成されている光拡散板４０において、光拡散板４０の厚さｄは、凸状部４１の頂部と第１の面４０ａとの間の距離とすることができる。 1 and 2, the light diffusing plate 40 has a substantially flat first surface 40a on the light source unit 30 side and a second surface 40b on the transmissive image display unit 10 side. A plurality of convex portions 41 are formed on the second surface 40b. In the light diffusing plate 40 in which the convex portion 41 is formed, the thickness d of the light diffusing plate 40 can be a distance between the top of the convex portion 41 and the first surface 40a.
　図２に示すように、各凸状部４１は、一方向（第１の方向）に延在している線状の光学要素である。光学要素の例は、レンズやプリズムである。複数の凸状部４１は、凸状部４１の延在方向に略直交する方向（第２の方向）に並列配置されている。複数の凸状部４１は、第２の面４０ｂの全面に形成されている。隣接する凸状部４１の断面形状における端４１ａは凸状部４１の配列方向において重なっている。 As shown in FIG. 2, each convex portion 41 is a linear optical element extending in one direction (first direction). Examples of optical elements are lenses and prisms. The plurality of convex portions 41 are arranged in parallel in a direction (second direction) substantially orthogonal to the extending direction of the convex portions 41. The plurality of convex portions 41 are formed on the entire surface of the second surface 40b. The ends 41 a in the cross-sectional shape of the adjacent convex portions 41 overlap in the arrangement direction of the convex portions 41.
　各凸状部４１の延在方向に直交する断面形状は複数の凸状部４１間で略同一である。離間距離Ｄ及び隣接する２つの光源３１，３１間の距離Ｌの比であるＬ／Ｄが２以上、好ましくは、２．５以上という条件を満たすように、離間距離Ｄ及距離Ｌが選択されることは、上述したとおりである。 The cross-sectional shape orthogonal to the extending direction of each convex portion 41 is substantially the same among the plurality of convex portions 41. The separation distance D and the distance L are selected so that L / D, which is the ratio of the separation distance D and the distance L between the two adjacent light sources 31, 31, is 2 or more, preferably 2.5 or more. This is as described above.
　図３は凸状部の延在方向に直交する断面形状の一例を示す図面であり、一つの凸状部を拡大して示している。凸状部４１の断面形状を、図３に示すように設定した局所的なｘｚ座標系を用いて説明する。ｘｚ座標系を構成するｘ軸は複数の凸状部４１の配列方向（第２の方向）に平行であり、ｚ軸は板厚方向（第１及び第２の方向に直交する方向）に平行である。 FIG. 3 is a drawing showing an example of a cross-sectional shape orthogonal to the extending direction of the convex portion, and shows an enlarged one convex portion. The cross-sectional shape of the convex portion 41 will be described using a local xz coordinate system set as shown in FIG. The x-axis constituting the xz coordinate system is parallel to the arrangement direction (second direction) of the plurality of convex portions 41, and the z-axis is parallel to the plate thickness direction (direction orthogonal to the first and second directions). It is.
　ｘｚ座標系のｘｚ面において、凸状部４１の断面形状は、式（３）を満たすｚ（ｘ）で表される。
Figure JPOXMLDOC01-appb-M000005
 　ただし、式（３）において、ｚ０（ｘ）は式（４）を満たす。
Figure JPOXMLDOC01-appb-M000006
 式（４）中、ｗａは凸状部４１のｘ軸方向の長さである。ｈａは０．５６ｗａ≦ｈａ＜０．５８ｗａの範囲から選択される定数である。ｋａは－０．０３９≦ｋａ＜－０．０２７の範囲から選択される定数である。ｈａは、凸状部４１をｚ０（ｘ）で表される形状とした場合における凸状部４１の両端４１ａ，４１ａ間のｚ軸方向の最大高さに対応する。ｋａは、凸状部４１のとがり方を示すパラメータである。ｈａ，ｋａの例は、ｈａ＝０．５６ｗａ、ｋａ＝－０．０３９である。図３では、式(３)を満たす範囲内でｚ０（ｘ）をｚ方向に所定倍（例えば１倍）だけ伸縮した形状を例示している。図３に示した一例では、両端４１ａ，４１ａがｘ軸上に位置するとともに、頂部４１ｂがｚ軸上に位置する。凸状部４１はｚ軸に対して対称な輪郭線を有する。 In the xz plane of the xz coordinate system, the cross-sectional shape of the convex portion 41 is represented by z (x) that satisfies Expression (3).
Figure JPOXMLDOC01-appb-M000005
 However, in Formula (3), z 0 (x) satisfies Formula (4).
Figure JPOXMLDOC01-appb-M000006
 In formula (4), w a is the length of the convex portion 41 in the x-axis direction. h a is a constant selected from the range of 0.56 w a ≦ h a <0.58 w a . k a is a constant selected from the range of −0.039 ≦ k a <−0.027. h a corresponds to the maximum height in the z-axis direction between both ends 41a and 41a of the convex portion 41 when the convex portion 41 has a shape represented by z 0 (x). k a is a parameter indicating how the convex portion 41 is sharpened. Examples of h a, k a is, h a = 0.56w a, a k a = -0.039. FIG. 3 illustrates a shape in which z 0 (x) is expanded and contracted by a predetermined multiple (for example, one time) in the z direction within a range satisfying the expression (3). In the example shown in FIG. 3, both ends 41a and 41a are located on the x-axis, and the top 41b is located on the z-axis. The convex portion 41 has a contour line that is symmetric with respect to the z-axis.
　凸状部４１の輪郭線は、ｚ０（ｘ）をｚ方向に所定倍（例えば１倍）だけ伸縮した形状に限定されない。凸状部４１の輪郭線は、式（３）を満たしていればよい。式（３）においてｚ（ｘ）は、図４に示すように、ある幅ｗａに対してｚ０（ｘ）を決定した際に、０．９５ｚ０（ｘ）で表される輪郭線と、１．０５ｚ０（ｘ）で表される輪郭線の間の領域をとおる輪郭線であればよい。 The contour line of the convex portion 41 is not limited to a shape in which z 0 (x) is expanded and contracted by a predetermined time (for example, 1 time) in the z direction. The outline of the convex part 41 should just satisfy | fill Formula (3). In Expression (3), z (x) is an outline represented by 0.95z 0 (x) when z 0 (x) is determined for a certain width w a as shown in FIG. 1.05z 0 (x), any contour line passing through the region between the contour lines may be used.
　凸状部４１の幅ｗａは、凸状部４１の形成が容易であることから、通常４０μｍ以上、好ましくは８０μｍ以上であり、凸状部４１に起因する模様が肉眼で視認されにくいことから、通常８００μｍ以下、好ましくは４５０μｍ以下である。幅ｗａの具体例は、４１０μｍ、４００μｍ、３２５μｍ、２８０μｍ及び１００μｍである。ただし、ｗａの値はこれに限定されない。　 Width w a of the convex portion 41, since formation of the convex portion 41 is easy, usually 40μm or more, preferably 80μm or more, since the pattern due to the convex portion 41 is hardly visible to the naked eye Usually, it is 800 μm or less, preferably 450 μm or less. Specific examples of width w a is, 410μm, 400μm, 325μm, a 280μm and 100 [mu] m. However, the value of w a is not limited to this.
　図５を利用して凸状部４１の輪郭線の一例及び凸状部４１の輪郭線が満たすべき条件を具体的に示す。図５は凸状部の輪郭線の一例及び凸状部の輪郭線が満たすべき条件を示す図面である。図５の横軸は位置（μｍ）を示し、縦軸は高さ（μｍ）を示している。図５に示した例では、ｗａ＝１００μｍ、ｈａ＝０．５７ｗａ、ｋａ＝－０．０３３とする。これらの数値で決まるｚ０（ｘ）を、便宜的にｚ１０（ｘ）と称す。図５ではｚ（ｘ）＝ｚ１０（ｘ）の場合の輪郭線形状を示している。 An example of the contour line of the convex portion 41 and conditions that the contour line of the convex portion 41 should satisfy are specifically shown using FIG. FIG. 5 is a drawing showing an example of the contour line of the convex portion and the conditions that the contour line of the convex portion should satisfy. The horizontal axis in FIG. 5 indicates the position (μm), and the vertical axis indicates the height (μm). In the example shown in FIG. 5, it is assumed that w a = 100 μm, h a = 0.57 w a , and k a = −0.033. Z 0 (x) determined by these numerical values is referred to as z1 0 (x) for convenience. FIG. 5 shows an outline shape in the case of z (x) = z1 0 (x).
　図５では、上記ｚ１０（ｘ）に基づいた輪郭線が満たす条件を説明するために、ｚ１０（ｘ）で表される輪郭線とともに、０．９５ｚ１０（ｘ）で示される輪郭線（図中の破線）及び１．０５ｚ１０（ｘ）で示される輪郭線（図中の一点鎖線）を示している。凸状部４１の輪郭線は、式（３）を満たせばよいので、０．９５ｚ１０（ｘ）で表される輪郭線と、１．０５ｚ１０（ｘ）で表される輪郭線との間の領域を通るものであればよい。 In Figure 5, in order to explain the condition that contour lines based on the above z1 0 (x) satisfies, with contour lines represented by z1 0 (x), the contour lines shown by 0.95z1 0 (x) ( A contour line (dashed line in the figure) indicated by a broken line in the figure) and 1.05z1 0 (x) is shown. Contour of the convex portion 41, so should satisfy equation (3), between a contour line represented by 0.95z1 0 (x), a contour line represented by 1.05z1 0 (x) As long as it passes through this area.
　上記形状例１では、ｗａ＝１００μｍとしたがこれに限定されないことは前述したとおりである。 In the first shape example, w a = 100 μm, but it is not limited to this, as described above.
　上記説明では、凸状部４１の断面形状が式（３）を満たすｚ（ｘ）で表されるとした。ただし、凸状部４１の断面形状は、－０．４７５ｗａ≦ｘ≦０．４７５ｗａにおいて式（３）を満たすｚ（ｘ）で表されていればよい。凸状部４１の裾付近（端部近傍）では成形誤差が比較的大きくなる傾向にある一方、裾付近の形状が光の拡散性に与える影響は小さいからである。 In the above description, it is assumed that the cross-sectional shape of the convex portion 41 is represented by z (x) that satisfies Expression (3). However, the cross-sectional shape of the convex portion 41 may be expressed by z (x) that satisfies the expression (3) when −0.475 w a ≦ x ≦ 0.475 w a . This is because the molding error tends to be relatively large in the vicinity of the bottom of the convex portion 41 (in the vicinity of the end), but the shape of the vicinity of the bottom has little influence on the light diffusibility.
　図２に示した光拡散板４０を透過型画像表示装置１に適用する場合、光拡散板４０を、凸状部４１の延在方向（第１の方向）が画面の横方向になるように配置してもよいし、縦方向になるように配置してもよい。 When the light diffusing plate 40 shown in FIG. 2 is applied to the transmissive image display device 1, the light diffusing plate 40 is arranged such that the extending direction (first direction) of the convex portion 41 is the horizontal direction of the screen. You may arrange | position and may arrange | position so that it may become a vertical direction.
　式（３）を満たすように凸状部４１の断面形状を設計し、例えば透明材料から削り出す方法によって、光拡散板４０を製造することができる。また、透明材料として透明樹脂材料を用いる場合は、例えば射出成形法、押出成型法、プレス成形法、フォトポリマー法などの方法によって光拡散板４０を製造することができる。 The light diffusing plate 40 can be manufactured by designing the cross-sectional shape of the convex portion 41 so as to satisfy Equation (3) and, for example, by cutting out from a transparent material. When a transparent resin material is used as the transparent material, the light diffusing plate 40 can be manufactured by a method such as an injection molding method, an extrusion molding method, a press molding method, or a photopolymer method.
　光拡散板４０を含む面光源装置２０及び透過型画像表示装置１では、光源部３０の各光源３１から出力された光は、直接又はランプボックス３２の内面３２ａで反射して光拡散板４０に入射される。光拡散板４０に入射した光は、第２の面４０ｂから透過型画像表示部１０に向けて照射される。第２の面４０ｂには、凸状部４１が複数形成されているため、凸状部４１を介して光が出射される。その結果、光拡散板４０によって面状の光が生成される。この際、凸状部４１が上記ｚ（ｘ）で表される断面形状を有することで、輝度の不均一を抑制可能である。 In the surface light source device 20 and the transmissive image display device 1 including the light diffusing plate 40, the light output from each light source 31 of the light source unit 30 is reflected directly or by the inner surface 32 a of the lamp box 32 to the light diffusing plate 40. Incident. The light incident on the light diffusing plate 40 is irradiated from the second surface 40b toward the transmissive image display unit 10. Since a plurality of convex portions 41 are formed on the second surface 40 b, light is emitted through the convex portions 41. As a result, planar light is generated by the light diffusion plate 40. At this time, since the convex portion 41 has a cross-sectional shape represented by z (x), it is possible to suppress nonuniform luminance.
　凸状部４１の断面形状が式（３）を満たすｚ（ｘ）で表されることから、例えば光拡散板４０の光源３１に対する位置ずれや熱などによる変形でＬ／Ｄが所定の値（例えば設計値）から変動しても、輝度の不均一が生じにくく、より安定して輝度の不均一を抑制できる。 Since the cross-sectional shape of the convex portion 41 is represented by z (x) satisfying the expression (3), for example, the L / D is a predetermined value (deformation due to displacement of the light diffusion plate 40 with respect to the light source 31 or heat). For example, even if it fluctuates from the design value), non-uniform luminance is less likely to occur, and the non-uniform luminance can be suppressed more stably.
　光拡散板４０が輝度の不均一を抑制可能であり、更に、安定して輝度の不均一を抑制できる点について、シミュレーション結果を参照して具体的に説明する。 The point that the light diffusing plate 40 can suppress non-uniformity in luminance and can further stably suppress non-uniform luminance will be specifically described with reference to simulation results.
　シミュレーションは、図２に示したように、複数の光源３１上に光拡散板４０を配置した構成において実施した。また、光拡散板４０の屈折率は、凸状部４１を含めて１．５１とした。シミュレーションでは、光拡散板４０からの出射光を光線追跡法により求め、ｚ方向に直交する面における輝度均斉度（％）を算出した。輝度均斉度（％）は、「（最低輝度／最高輝度）×１００」によって算出した。 The simulation was performed in a configuration in which a light diffusion plate 40 is disposed on a plurality of light sources 31 as shown in FIG. The refractive index of the light diffusing plate 40 was 1.51 including the convex portion 41. In the simulation, the light emitted from the light diffusing plate 40 was obtained by the ray tracing method, and the luminance uniformity (%) in the plane orthogonal to the z direction was calculated. The brightness uniformity (%) was calculated by “(lowest brightness / highest brightness) × 100”.
　ミュレーションでの凸状部４１の断面形状の輪郭線はｚ（ｘ）＝ｚ０（ｘ）である。ｚ０（ｘ）に含まれるｈａ及びｋａが、上述した範囲（すなわち、０．５６ｗａ≦ｈａ＜０．５８ｗａ及び－０．０３９≦ｋａ＜－０．０２７）の場合を実施例とし、上記範囲以外の場合を比較例として説明する。 The contour line of the cross-sectional shape of the convex portion 41 in the simulation is z (x) = z 0 (x). z 0 (x) h a and k a are included in the the case of the above-described range (i.e., 0.56w a ≦ h a <0.58w a and -0.039 ≦ k a <-0.027) A case outside the above range will be described as a comparative example.
　実施例１、比較例１及び比較例２では、隣接する２つの光源３１の間隔Ｌを３０ｍｍとし、光源３１と光拡散板４０との距離Ｄを１５ｍｍとした。この場合、Ｌ／Ｄ＝２．００である。表１に実施例１、比較例１及び比較例２で設定したｈａ、ｋａの値と共に、シミュレーションより得られた輝度均斉度の結果を示す。表１において、ｗａ＝１００μｍである。
Figure JPOXMLDOC01-appb-T000007
 In Example 1, Comparative Example 1, and Comparative Example 2, the distance L between two adjacent light sources 31 was 30 mm, and the distance D between the light source 31 and the light diffusion plate 40 was 15 mm. In this case, L / D = 2.00. Example Table 1 1, h a set in Comparative Example 1 and Comparative Example 2, with the value of k a, shows the results of the uniformity ratio of luminance Simulation. In Table 1, w a = 100 μm.
Figure JPOXMLDOC01-appb-T000007
　表１に示すように、実施例１は８８．４％の輝度均斉度を実現する。凸状部４１の断面形状以外の実施例１、比較例１及び比較例２の条件は同じである。従って、凸状部４１の断面形状を実施例１の形状とすることで、比較例１及び比較例２より高い輝度均斉度を得ることが可能である。 As shown in Table 1, Example 1 achieves a brightness uniformity of 88.4%. The conditions of Example 1, Comparative Example 1, and Comparative Example 2 other than the cross-sectional shape of the convex portion 41 are the same. Therefore, by setting the cross-sectional shape of the convex portion 41 to the shape of Example 1, it is possible to obtain a higher luminance uniformity than Comparative Example 1 and Comparative Example 2.
　実施例２として、実施例１に対してＬ／Ｄを変更した条件でシミュレーションを実施した。光源３１と光拡散板４０との距離Ｄを１４ｍｍとした点以外は、実施例１の場合と同様の条件で実施例２のシミュレーションを行った。実施例２では、Ｌ／Ｄ＝２．１４である。表２に実施例２のシミュレーション結果を示す。表２においても、ｗａ＝１００μｍである。
Figure JPOXMLDOC01-appb-T000008
 As Example 2, a simulation was performed under the condition that L / D was changed from Example 1. The simulation of Example 2 was performed under the same conditions as in Example 1 except that the distance D between the light source 31 and the light diffusion plate 40 was 14 mm. In Example 2, L / D = 2.14. Table 2 shows the simulation results of Example 2. Also in Table 2, w a = 100 μm.
Figure JPOXMLDOC01-appb-T000008
　実施例２のシミュレーション条件では、Ｌ／Ｄは２．１４であることから、実施例２のＬ／Ｄは、実施例１の場合のＬ／Ｄに対して変動している。しかしながら、実施例２は、８３．６％という輝度均斉度を実現する。すなわち、断面形状が式（３）を満たすｚ（ｘ）で表される凸状部４１を有することにより、光拡散板４０は、Ｌ／Ｄが所定の値（例えば設計値）から変動しても、輝度の不均一が生じにくく、より安定して輝度の不均一を抑制できる。 Since the L / D is 2.14 under the simulation conditions of the second embodiment, the L / D of the second embodiment varies with the L / D of the first embodiment. However, Example 2 achieves a brightness uniformity of 83.6%. That is, by having the convex portion 41 represented by z (x) whose cross-sectional shape satisfies the expression (3), the light diffusion plate 40 has an L / D that varies from a predetermined value (for example, a design value). However, non-uniform luminance is less likely to occur, and the non-uniform luminance can be suppressed more stably.
　上述した作用効果を光拡散板４０が有するので、光拡散板４０を備える面光源装置２０は、輝度の不均一が抑制された光を出力することができる。光拡散板４０を含む透過型画像表示装置１では、輝度の不均一が抑制された光によって透過型画像表示部１０を照明できるので、透過型画像表示装置１は、表示品質の向上を図ることができる。光拡散板４０を備える面光源装置２０でも、輝度の不均一が抑制された光をより安定して出力可能である。光拡散板４０を備える透過型画像表示装置１では、表示品質の向上を図りながら、光拡散板４０の光源３１に対する位置ずれや熱などによる変形による表示品質の変動を抑制可能である。 Since the light diffusing plate 40 has the above-described effects, the surface light source device 20 including the light diffusing plate 40 can output light in which unevenness in luminance is suppressed. In the transmissive image display device 1 including the light diffusing plate 40, the transmissive image display unit 10 can be illuminated by light with suppressed luminance non-uniformity. Therefore, the transmissive image display device 1 can improve display quality. Can do. Even the surface light source device 20 including the light diffusing plate 40 can more stably output light in which nonuniform luminance is suppressed. In the transmissive image display device 1 including the light diffusing plate 40, it is possible to suppress a change in display quality due to a displacement of the light diffusing plate 40 with respect to the light source 31 or deformation due to heat or the like while improving display quality.
　以上、本発明の実施形態について説明したが、本発明は上記実施形態に限定されない。例えば光制御板を光拡散板４０として説明したが、本発明はこれに限定されない。光制御板は、複数の光源から出力された光の、複数の光源が配置される平面に平行な平面内での輝度の均一性を調整する光部品であればよい。例えば、光制御板は、透明材料からなる板の光の出射側に、上述した凸状部を複数有する、プリズムシートやレンズシートなどの光学シート又は光学フィルムといった輝度調整板とすることもできる。更に、隣接する凸状部４１の断面形状における端４１ａは凸状部４１の配列方向において重なっているとして説明した。しかしながら、光拡散板４０の断面形状において、隣接する２つの凸状部４１のうちの一方の凸状部４１の端４１ａと他方の凸状部４１の端４１ａの間に平坦部（例えば製造誤差により生じる程度のもの）などが生じているものとすることができる。 As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. For example, although the light control plate has been described as the light diffusion plate 40, the present invention is not limited to this. The light control plate may be an optical component that adjusts the luminance uniformity of light output from a plurality of light sources in a plane parallel to a plane on which the plurality of light sources are arranged. For example, the light control plate may be a brightness adjusting plate such as an optical sheet such as a prism sheet or a lens sheet or an optical film having a plurality of the convex portions described above on the light emission side of a plate made of a transparent material. Further, it has been described that the end 41a in the cross-sectional shape of the adjacent convex portions 41 overlaps in the arrangement direction of the convex portions 41. However, in the cross-sectional shape of the light diffusing plate 40, a flat portion (for example, a manufacturing error) between the end 41a of one convex portion 41 and the end 41a of the other convex portion 41 of the two adjacent convex portions 41. Or the like generated by the above).
　光拡散板４０は、単独の透明材料で構成された単層板であってもよい。光拡散板４０は、互いに異なる透明材料で構成された層が積層された構造の多層板であってもよい。 The light diffusion plate 40 may be a single layer plate made of a single transparent material. The light diffusing plate 40 may be a multilayer plate having a structure in which layers made of different transparent materials are laminated.
　図６は、多層板とした場合の光拡散板の一例の断面図である。図６に示すように、多層板としての光拡散板５０は、スキン層５１と、スキン層５１上に設けられた基体部５２と、基体部５２上に設けられた凸状部形成層５３とを有する。スキン層５１と基体部５２との間の界面及び基体部５２と凸状部形成層５３との界面は、図６に示すように平坦である。 FIG. 6 is a cross-sectional view of an example of a light diffusion plate in the case of a multilayer plate. As shown in FIG. 6, the light diffusing plate 50 as a multilayer plate includes a skin layer 51, a base portion 52 provided on the skin layer 51, and a convex portion forming layer 53 provided on the base portion 52. Have The interface between the skin layer 51 and the base portion 52 and the interface between the base portion 52 and the convex portion forming layer 53 are flat as shown in FIG.
　凸状部形成層５３は、複数の凸状部４１が凸状部４１の延在方向に直交する方向に配列されて構成された形状付与層である。凸状部４１の形状は、図２に示したものと同じである。凸状部形成層５３が有する各凸状部４１は透明材料からなる。各凸状部４１の屈折率は１．５０以上且つ１．５２未満とすることができる。 The convex portion forming layer 53 is a shape imparting layer configured by arranging a plurality of convex portions 41 in a direction orthogonal to the extending direction of the convex portions 41. The shape of the convex portion 41 is the same as that shown in FIG. Each convex portion 41 included in the convex portion forming layer 53 is made of a transparent material. The refractive index of each convex part 41 can be 1.50 or more and less than 1.52.
　基体部５２は、透明材料からなる板状体である。基体部５２の屈折率は１．５０以上且つ１．５２未満とすることができる。基体部５２の屈折率は、凸状部４１の屈折率と異なっていてもよい。しかしながら、基体部５２の屈折率は、凸状部４１の屈折率と同じであることが好ましい。 The base portion 52 is a plate-like body made of a transparent material. The refractive index of the base portion 52 can be 1.50 or more and less than 1.52. The refractive index of the base portion 52 may be different from the refractive index of the convex portion 41. However, the refractive index of the base portion 52 is preferably the same as the refractive index of the convex portion 41.
　スキン層５１も透明材料からなる板状体である。スキン層５１において基体部５２と反対側の面は平坦である。スキン層５１の厚さは基体部５２より薄い。スキン層５１の厚さの例は、１０μｍ以上且つ１００μｍ未満である。スキン層５１の屈折率は基体部５２との屈折率差が０．１以下のものとすることができる。スキン層５１の屈折率は基体部５２と同じ屈折率であることが好ましい。 The skin layer 51 is also a plate-like body made of a transparent material. The surface of the skin layer 51 opposite to the base portion 52 is flat. The skin layer 51 is thinner than the base portion 52. An example of the thickness of the skin layer 51 is 10 μm or more and less than 100 μm. The skin layer 51 may have a refractive index difference of 0.1 or less with respect to the base portion 52. The refractive index of the skin layer 51 is preferably the same as that of the base portion 52.
　基体部５２が樹脂からなる場合、スキン層５１は、好ましくは、紫外線吸収剤を含む。紫外線吸収剤をスキン層５１が含むことによって、例えば、蛍光管のように出力光に紫外線を含む光源３１を用いた場合、光源３１からの紫外線による光拡散板の劣化を防止できるからである。また、基体部５２が吸湿性を有する場合には、スキン層５１を構成する材料は、吸湿を抑制する材料とすることができる。凸状部５３が吸湿性を有する場合には、スキン層５１を構成する材料は、凸状部５３より吸湿し易い材料とすることができる。 When the base portion 52 is made of a resin, the skin layer 51 preferably contains an ultraviolet absorber. This is because, when the skin layer 51 contains the ultraviolet absorber, for example, when the light source 31 including ultraviolet rays is used as output light like a fluorescent tube, deterioration of the light diffusion plate due to the ultraviolet rays from the light source 31 can be prevented. Moreover, when the base | substrate part 52 has a hygroscopic property, the material which comprises the skin layer 51 can be made into the material which suppresses moisture absorption. When the convex part 53 has a hygroscopic property, the material which comprises the skin layer 51 can be made into the material which absorbs moisture more easily than the convex part 53. FIG.
　これまでの説明では、光源部３０が有する複数の光源３１は、間隔Ｌでほぼ等間隔に配置されているとした。しかしながら、隣接する２つの光源３１，３１間の距離は異なっていても良い。この場合は、隣接する２つの光源３１，３１間の間隔の平均距離Ｌｍを使用して、光源３１間の距離と、光源３１と光制御板との間の距離の比を定義することができる。 In the description so far, it is assumed that the plurality of light sources 31 included in the light source unit 30 are arranged at substantially equal intervals with the interval L. However, the distance between the two adjacent light sources 31 may be different. In this case, by using the average distance L m intervals between 31 and 31 adjacent two light sources, and the distance between the light source 31, to define the ratio of the distance between the light source 31 and the light control plate it can.
　１…透過型画像表示装置、１０…透過型画像表示部、２０…面光源装置、３０…光源部、３１…光源、４０…光拡散板(光制御板)、４０ａ…第１の面、４０ｂ…第２の面、４１…凸状部、４１ａ…凸状部の端、４１ｂ…凸状部の頂部。 DESCRIPTION OF SYMBOLS 1 ... Transmission type image display apparatus, 10 ... Transmission type image display part, 20 ... Surface light source device, 30 ... Light source part, 31 ... Light source, 40 ... Light diffusing plate (light control board), 40a ... 1st surface, 40b ... 2nd surface, 41 ... convex part, 41a ... end of convex part, 41b ... top part of convex part.

Claims (4)

  1. 　第１の面から入射した光を前記第１の面と反対側に位置する第２の面から出射する光制御板であって、
    　第２の面に形成される複数の凸状部を備え、
    　複数の前記凸状部の各々は、第１の方向に延在しており、複数の前記凸状部は、前記第１の方向に直交する第２の方向に並列配置されており、
    　複数の前記凸状部の各々の前記第１の方向に直交する断面において、前記第２の方向に対する各前記凸状部の両端をとおる軸をｘ軸とし、前記ｘ軸上において前記両端の中心をとおり前記ｘ軸に直交する軸をｚ軸とし、各前記凸状部のｘ軸方向の長さをｗａとしたとき、前記断面における各前記凸状部の輪郭形状が、－０．４７５ｗａ≦ｘ≦０．４７５ｗａにおいて、式（１）を満たすｚ（ｘ）で表される、光制御板。
    Figure JPOXMLDOC01-appb-M000001
     　ただし、式（１）において、ｚ０(x)は、式（２）を満たす。
    Figure JPOXMLDOC01-appb-M000002
     （式(２)中、ｈａは０．５６ｗａ以上且つ０．５８ｗａ未満の数、ｋａは－０．０３９以上且つ－０．０２７未満の数）     A light control plate that emits light incident from a first surface from a second surface located on the opposite side of the first surface;
    A plurality of convex portions formed on the second surface;
    Each of the plurality of convex portions extends in a first direction, and the plurality of convex portions are arranged in parallel in a second direction orthogonal to the first direction,
    In a cross section orthogonal to the first direction of each of the plurality of convex portions, an axis passing through both ends of each convex portion with respect to the second direction is an x axis, and the centers of the both ends on the x axis When the z-axis is the axis perpendicular to the x-axis and the length in the x-axis direction of each convex portion is w a , the contour shape of each convex portion in the cross section is −0.475 w. in a ≦ x ≦ 0.475w a, represented by z (x) satisfying the equation (1), the light control plate.
    Figure JPOXMLDOC01-appb-M000001
     However, in the formula (1), z 0 (x) satisfies the formula (2).
    Figure JPOXMLDOC01-appb-M000002
     (Wherein (in 2), h a is a number less than 0.56W a more and 0.58w a, k a is a number less than -0.039 or more and -0.027)
  2. 　前記光制御板は透明材料からなり、
    　各前記凸状部の屈折率は１．５０以上且つ１．５２未満である、
    請求項１記載の光制御板。     The light control plate is made of a transparent material,
    The refractive index of each convex portion is 1.50 or more and less than 1.52.
    The light control board according to claim 1.
  3. 　請求項１又は請求項２に記載の光制御板と、
    　互いに離間して配置されており、前記光制御板の前記第１の面に光を供給する複数の光源と、
    を備える、面光源装置。     The light control plate according to claim 1 or 2,
    A plurality of light sources that are spaced apart from each other and that supply light to the first surface of the light control plate;
    A surface light source device.
  4. 　請求項１又は請求項２に記載の光制御板と、
    　互いに離間して配置されており、前記光制御板の前記第１の面に光を供給する複数の光源と、
    　前記光制御板の前記第２の面から出射された光によって照明されて画像を表示する透過型画像表示部と、
    を備える、透過型画像表示装置。     The light control plate according to claim 1 or 2,
    A plurality of light sources that are spaced apart from each other and that supply light to the first surface of the light control plate;
    A transmissive image display unit that displays an image illuminated by light emitted from the second surface of the light control plate;
    A transmissive image display device.
PCT/JP2011/050999 2010-01-22 2011-01-20 Light control plate, surface light source device, and transmission-type image display device WO2011090125A1 (en)

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