JP2011138691A - Light control board unit, planar light source device, and transmission image display device - Google Patents

Abstract

【選択図】なしProvided are a light control plate unit, a surface light source device, and a transmissive image display device capable of sufficiently uniformly dispersing light from a point light source.
First and second light control plates are provided, and a second light control plate is provided such that a lower surface thereof is positioned on an upper surface side of the first light control plate, and the first and second light control plates are provided. A plurality of convex portions extending in one direction are arranged in parallel on the upper surface of the plate, the extending directions of the convex portions are substantially orthogonal, and the axis passing through both ends of each cross section of the convex portion is the u axis. When the axis that passes through the center between both ends and is perpendicular to the u axis is the v axis, the contour shape v (u) in the cross section is 0.95v ₀ (u) ≦ v (u) ≦ 1.05v ₀ (u Is satisfied. However, v ₀ (u) satisfies the following formula (1).

[Selection figure] None

Description

  The present invention relates to a light control plate unit, a surface light source device, and a transmissive image display device.

  As a direct-type image display device 40 which is an example of a transmissive image display device, for example, as shown in FIG. 8, a device in which a light source 43 is disposed on the back side of the transmissive image display unit 10 is widely used. Examples of the transmissive image display unit 10 include a liquid crystal display panel in which linearly polarizing plates 12 and 13 are disposed on both surfaces of a liquid crystal cell 11. As the light source 43, a plurality of linear light sources such as a straight tube type cold cathode ray tube are arranged in parallel with each other.

  It is desirable that the direct image display device 40 can uniformly illuminate the transmissive image display unit 10 by uniformly dispersing light from the light source 43, and for this reason, between the light source 43 and the transmissive image display unit 10. A light control plate 42 such as a single light diffusing plate having a function of changing the direction of light incident from the light source 43 side and emitting it from the opposite transmissive image display unit 10 side is used. (For example, see Patent Document 1: Japanese Patent Laid-Open No. 7-198913). Since the light output from the light source 43 is emitted as planar light by the light control plate 42, the light source 43 and the light control plate 42 constitute a surface light source device 41.

JP-A-7-198913

  In recent years, it has been studied to use a light emitting diode as a light source from the viewpoint of energy saving instead of a straight tube type cold cathode ray tube. The light emitting diode is usually a point light source, and is used by arranging it in a discrete manner.

  However, when the conventional light control plate is used in a direct type image display device in combination with a point light source such as a light emitting diode, the light from the point light source cannot be made sufficiently uniform, and the transmission type The image displayed by the image display unit has a problem that the brightness differs between the vicinity of the point light source and the position away from the point light source.

  Therefore, an object of the present invention is to provide a light control plate unit, a surface light source device, and a transmissive image display device that can sufficiently uniformly disperse light from a point light source.

ただし、前記式（１）において、

（式（２）中、ｈ_ａは、０．４０ｗ_ａ以上１．６０ｗ_ａ以下を満たす定数であり、ｋ_ａは−１．００以上且つ−０．１５以下を満たす定数である） The light control plate unit according to the present invention can emit light incident from the first surface from the second surface located on the opposite side of the first surface, and extends in one direction. A plurality of convex portions arranged in parallel in a direction substantially perpendicular to the one direction are provided with first and second light control plates formed on the second surface. The second light control plate is provided on the first light control plate, and the first surface of the second light control plate is located on the second surface side of the first light control plate, The extending direction of the convex portion included in the first light control plate is substantially orthogonal to the extending direction of the convex portion included in the second light control plate, and the first and second light control plates have. Each of the convex portions has an axis passing through both ends in a cross section orthogonal to the extending direction of each of the convex portions of the first and second light control plates as a u axis, and a center between both ends on the u axis. Assuming that the axis perpendicular to the u-axis is the v-axis and the length in the u-axis direction is w _a for each of the convex portions of the first and second light control plates, Each contour shape of the convex portion of the second light control plate is represented by v (u) that satisfies the following expression (1) when −0.475 w _a ≦ u ≦ 0.475 w _a . It is characterized by that.

However, in the formula (1),

(In the formula (2), _{h a} is a constant satisfying the following 0.40 W _a or 1.60 W _{a, k a} is a constant satisfying -1.00 or more and -0.15 or less)

  In this configuration, light incident from the first surface of the first light control plate is emitted from the second surface. Then, the light emitted from the second surface of the first light control plate enters the first surface of the second light control plate and is emitted from the second surface of the second light control plate. Each of the first and second light control plates of the light diffusing plate unit has a plurality of convex portions formed on the second surface. Since the convex portion of each of the first and second light control plates has a cross-sectional shape represented by v (u) that satisfies the above formula (1), the first and second light control plates are Light from a point light source can be converted into light that is linear and has a substantially uniform luminance in its extending direction. And the 1st and 2nd light control board is arrange | positioned so that the extending direction of the convex part which each of the 1st and 2nd light control board has substantially orthogonally crosses. Therefore, the light control plate unit can uniformly disperse the light from the point light source disposed on the first surface side of the first light control plate to obtain planar light.

  In the light control plate unit according to the present invention, the first surface of each of the first and second light control plates can be substantially flat.

The surface light source device according to the present invention is provided on the light control plate unit according to the present invention and the first light control plate side of the light control plate unit, and the first surface of the first light control plate. A plurality of point light sources for supplying light to the light source.

  In this surface light source device, light output from a plurality of point light sources is emitted through the light control plate unit according to the present invention. Therefore, it is possible to uniformly disperse light from a plurality of point light sources to form planar light.

A transmissive image display device according to the present invention includes a light control plate unit according to the present invention, a plurality of point light sources for supplying light to the light control plate unit, and a second light control plate of the light control plate unit. And a transmissive image display unit that displays an image irradiated with light emitted from the light control plate unit.

  In this transmissive image display device, the transmissive image display unit is illuminated with light output from a plurality of point light sources and emitted through the light control unit according to the present invention. As a result, the transmissive image display unit is illuminated with the planar light in which the light from the point light source is more uniformly dispersed, so that a higher quality image can be displayed.

  According to the present invention, it is possible to provide a light control plate unit capable of sufficiently uniformly dispersing light from a point light source, a surface light source device including the light control unit, and a transmissive image display device. .

It is sectional drawing which shows typically the structure of the transmissive image display apparatus which concerns on this invention. It is drawing which shows an example of arrangement | positioning of a point light source. It is drawing which shows the other example of arrangement | positioning of a point light source. It is drawing which shows an example of the light distribution of the point light source used for the transmissive | pervious image display shown in FIG. It is a perspective view which shows an example of the light control board unit which concerns on this invention. It is drawing which shows the example of the cross-sectional shape of the convex part which the 1st and 2nd light control board of the light control board unit shown in FIG. 5 has. It is drawing which shows the conditions which the cross-sectional shape of a convex-shaped part satisfy | fills. It is sectional drawing which shows typically the structure of the conventional transmissive image display apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or an equivalent element, and the overlapping description is abbreviate | omitted. The dimensional ratios in the drawings do not necessarily match those described.

  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 shows the transmissive image display device 1 in an exploded manner.

  The transmissive image display device 1 includes a transmissive image display unit 10 and a surface light source device 20 disposed on the back side of the transmissive image display unit 10 in FIG. In the following description, as shown in FIG. 1, the arrangement direction of the surface light source device 20 and the transmissive image display unit 10 is referred to as a z direction (plate thickness direction), which is two directions orthogonal to the z direction and orthogonal to each other. Two directions are referred to as an x direction and a y direction.

  Examples of the transmissive image display unit 10 include a liquid crystal display panel in which linearly polarizing plates 12 and 13 are disposed on both surfaces of a liquid crystal cell 11. 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 the transmissive image display device 1 such as a conventional liquid crystal display device can be used. Examples of the liquid crystal cell 11 include known liquid crystal cells such as TFT type and STN type.

  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 diffusing plate unit (light control plate unit) 21 and a plurality of point light sources 22 arranged on the back side in FIG.

The light diffusion plate unit 21 includes first and second light diffusion plates 30 ₁ and 30 ₂ . First and second light diffusing plate ₃₀ 1, 30 _2, first light diffusing plate 30 ₁ is provided in the thickness direction (z-direction) to the second order of the light diffusion plate 30 _2. The first and second light diffusing plates 30 ₁ and 30 ₂ constituting the light diffusing plate unit 21 have substantially the same plan view shape (shape viewed from the z direction), and are usually rectangular. First and second light diffusing plate 30 _1, 30 ₂ of the plan view shape, in other words, the size of the planar shape of the light diffusing plate unit 21 is adapted to the screen size of the transmissive image display device 1 for the purpose However, it is usually 250 mm × 440 mm or more, preferably 1020 mm × 1800 mm or less. First plan view shape of the light diffusing plate 30 ₁ and the second light diffusion plate 30 ₂ is not limited to a rectangle, it may be square, but in the following, unless otherwise specified, be described as a rectangle.

  The plurality of point light sources 22 can be arranged according to the planar view shape of the light diffusing plate unit 21 or the transmissive image display unit 10.

FIG. 2 is a drawing showing an example of the arrangement relationship of a plurality of point light sources. As shown in FIG. 2, the plurality of point light sources 22 can be arranged at equal intervals L _{x in the} x direction and at equal intervals L _y in the y direction. In FIG. 2, as an example, the interval Lx in the x direction is larger than the interval Ly in the y direction, but the interval Ly may be larger than the interval Lx, or the interval Lx and the interval Ly may be the same. The space | interval Lx and the space | interval Ly can be made into the distance between the light emission parts of the point light source 22, and are 10 mm-150 mm normally.

  The plurality of point light sources 22 may be arranged in a staggered pattern shown in FIG. Since FIG. 3 can be regarded as a modification of the case of FIG. 2, the distance between the point light sources 22 in the x direction and the y direction can be the same as in the case of FIG. This will be specifically described.

  The rectangular lattice shown in FIG. 2 can be regarded as a plurality of point light source arrays composed of a plurality of point light sources 22 arranged in the x direction arranged in parallel in the y direction. In this case, the staggered arrangement in FIG. 3 is such that adjacent point light source arrays out of a plurality of point light source arrays arranged in the y direction are arranged with a half cycle shift in the x direction. Therefore, also in the arrangement shown in FIG. 3, the interval Ly in the y direction can be the same as the case shown in FIG. 2, that is, the interval between the point light source arrays arranged in parallel in the y direction. In FIG. 3, as an example, the point light source arrays arranged in parallel in the y direction are shifted by a half cycle in the x direction between adjacent point light source arrays. However, in the above description, the x direction and the y direction are opposite. There may be.

  An example of the point light source 22 is a light emitting diode. Moreover, as a light emitting diode, what is called side emission, what produces the maximum intensity | strength with respect to a certain angle direction with respect to z direction can be illustrated. FIG. 4 is a drawing showing the light distribution of OSRAM “Golden DRAGON (registered trademark) ARGUS (registered trademark)” as an example of the light distribution of light emitting diodes. In FIG. 4, the horizontal axis indicates the angle θ (see FIG. 1) with respect to the z direction, and the vertical axis indicates the intensity. The intensity is a value normalized with respect to the maximum intensity.

FIG. 5 is a perspective view for illustrating a configuration of a light diffusion plate unit (light control plate unit). With reference to FIG. 5, the first and second light diffusion plates 30 ₁ and 30 ₂ constituting the light diffusion plate unit 21 will be described. In FIG. 5, for the sake of explanation, the first and second light diffusion plates 30 ₁ and 30 ₂ are separated from each other, but the first light diffusion plate 301 is in contact with the _first light diffusion plate 301 as described later. 2 of a light diffuser 30 ₂ may be provided on the first upper light diffusion plate 30 _1.

[First light diffuser]
The first light diffusion plate 30 ₁ is substantially the (first surface of the first light control plate) 31 ₁ flat lower surface, the convex portion is convex second light diffusion plate 30 ₂ side (the first of the convex portion of the light control plate) 33 ₁ is a plate-like body having a second surface) 32 of _the plurality forming top surfaces (first light control plate. However, it may be in the form of a sheet or film depending on the thickness. Convex portion 33 ₁ extends substantially parallel to the Y1 direction in the y-direction (first direction of the first light control plate), first in the X1 direction (the first light control plate which is substantially perpendicular to the Y1 direction 2 direction). The X1 direction and the Y1 direction are preferably parallel to the x direction and the y direction, respectively, but may be shifted by about ± 10 ° due to, for example, a manufacturing error. The cross-sectional shape of the plurality of convex portions 33 ₁ is substantially the same between the convex portions 33 ₁ . Further, in the extending direction of the convex portion 33 _1, the cross-sectional shape is substantially uniform. The ends 33a ₁ of the two adjacent convex portions 33 ₁ and 33 ₁ are at the same position in the X1 direction. First thickness d1 of the light diffusion plate 30 ₁ is a z-direction distance between the top portion 33b ₁ of the lower surface 31 ₁ and the convex portion 33 _1, usually a 0.5 mm to 5 mm.

[Second light diffuser]
The second light diffusion plate 30 ₂ is substantially flat lower surface (second optical control plate first surface of) 31 _2, the convex portion is convex outward (convex portion of the second light control plate ) 33 ₂ is formed with a plurality of upper surface (fourth surface) 32 is a plate-like body having _two and. However, it may be in the form of a sheet or film depending on the thickness. Convex portion 33 ₂ extend in substantially parallel direction X2 in the x-direction (first direction of the second light control plate), first in the Y2 direction (the second light control plate substantially orthogonal to the X2 direction 2 direction). It is preferred X2 direction and the Y2 direction is parallel to the x and y directions, respectively, but as in the case of the first light diffuser 30 _1, for example due to a manufacturing error or the like may be offset about ± 10 °. Cross-sectional shape of the plurality of convex portions 33 ₂ is substantially same in the convex portion 33 _2. Further, in the extending direction of the convex portion 33 _2, the cross-sectional shape is substantially uniform. The ends 33a ₁ and 33a ₂ of the two adjacent convex portions 33 ₂ and 33 ₂ are at the same position in the Y2 direction. The second thickness d2 of the light diffusion plate 30 ₂ is a z-direction distance between the top portion 33b ₂ of the lower surface 31 ₂ and the convex portion 33 _2, usually a 0.1 mm to 5 mm.

[Convex]
The shape of the convex portions 33 ₁ and 33 _{2 included in} each of the first and second light diffusion plates 30 ₁ and 30 ₂ will be described. When the first and second light diffusion plates 30 ₁ and 30 ₂ are arranged on the point light source 22, the convex portions 33 ₁ and 33 ₂ emit light from the point light source 22 with substantially uniform luminance. It has a cross-sectional shape that can be converted into linear light. The cross-sectional shape of the convex portion ₃₃ 1, 33 ₂ will be described with reference to FIG.

Here, unless otherwise specified, the convex portions 33 ₁ and 33 ₂ are referred to as convex portions 33 _i (i is 1 or 2). In FIG. 6, the uv coordinate system is set with the u-axis as the direction orthogonal to the extending direction of the convex portion 33 _i . U-axis direction with respect to the convex portion 33 ₁ corresponds to the X1 direction, v-axis direction corresponds to the z-direction. U-axis direction with respect to the convex portion 33 ₂ corresponds to Y2 direction, v-axis direction corresponds to the z-direction.

ただし、前記式（３）において、

式（４）において、ｗ_ａはｕ軸方向の凸状部３３_ｉの長さである。ｈ_ａは、凸状部３３_ｉの両端３３ａ_ｉ,３３ａ_ｉ間における最大高さに対応し、ｈ_ａは０４０ｗ_ａ以上１．６０ｗ_ａ以下を満たす定数である。すなわち、ｈ_ａは、ｈ_ａ／ｗ_ａが０．４０以上１．６０以下を満たす定数である。ｋ_ａは−１．００以上且つ−０．１５以下を満たす定数である。凸状部３３_ｉの幅ｗ_aは、凸状部３３_ｉの形成が容易であることから、通常４０μｍ以上、好ましくは２５０μｍ以上であり、凸状部３３_ｉ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ｗ_aとして具体的には、ｗ_a＝４１０μｍ、ｗ_a＝４００μｍおよびｗ_a＝３２５μｍが例示できるが、ｗ_aの値はこれに限定されるものではない。 In the uv coordinate system, the cross-sectional shape of the convex portion 33 _i has both ends 33 a _i and 33 a _i on the u axis, and has a contour line symmetrical to the v axis. This contour line is represented by v (u) that satisfies the following formula (3).

However, in the formula (3),

In Expression (4), w _a is the length of the convex portion 33 _{i in} the u-axis direction. h _a is across 33a _i of the convex portion 33 _i, corresponding to the maximum height between 33a _{i, h a} is a constant satisfying the following 040W _a more 1.60 W _a. That is, h _a is a constant that satisfies h _a / w _a of 0.40 or more and 1.60 or less. k _a is _a constant that satisfies −1.00 or more and −0.15 or less. Width w _a of the convex portion 33 _i, since formation of the convex portion 33 _i is easy, usually 40μm or more, preferably 250μm or more, the pattern caused by the convex portion 33 _i is visible to the naked eye Since it is difficult, it is usually 800 μm or less, preferably 450 μm or less. Specific examples of the width w _a include w _a = 410 μm, w _a = 400 μm, and w _a = 325 μm, but the value of w _a is not limited to this.

FIG. 6 illustrates, as an example of a cross-sectional shape of the convex portion 33 _i, a shape in which v ₀ (u) is expanded and contracted by a predetermined multiple in the v direction within a range that satisfies Expression (3). However, the sectional shape of the convex portion 33 _i, as shown in FIG. 7, when determining the _v 0 (u) for a width _{w a,} contours represented by 0.95v ₀ (u) And a contour line passing through a region between the contour lines represented by 1.05v ₀ (u).

Further, in the above description, it is assumed that the cross-sectional shape of the convex portion 33 _i is represented by v (u) that satisfies Expression (3). However, considering the effect on the manufacturing error and the intensity distribution at near both ends of the convex portion 33 _i, the cross-sectional shape of the convex portion 33 _i has the formula in -0.475w _a ≦ u ≦ 0.475w _a It may be expressed by v (u) that satisfies (3).

Further, the range of h _{a /} w a and k _a may if they meet the above-mentioned range, but the distance between two adjacent point light sources 22 is L, the light diffusion plate from the light emitting portion of the point light sources 22 When the distance to the surface of the unit 21 on the point light source 22 side (the lower surface 31 _{1 of the first} light diffusing plate 30 ₁ in FIG. 1 or FIG. 5) is D, h _a / preferable for L / D range of w _a and _{k a} are as in Table 1 below. L described in Table 1 corresponds to Lx for contour shape of the convex portion 33 _1, and corresponds to Ly respect contour shape of the convex portion 33 _2.

With respect to the first light diffusing plate 30 ₁ of the convex portion 33 ₁ and the second light diffusion plate 30 _{and second} convex portions _{33 2, w a, h a} , k a is may be the same, or different Good. That is, the first convex portion 33 ₂ of the light diffusing plate 30 ₁ of the convex portion 33 ₁ and the second light diffusion plate 30 ₂ may be the same cross-sectional shapes, each convex Different cross-sectional shapes may be used as long as the contour lines of the cross-sectional shapes of the portions 33 ₁ and 33 ₂ satisfy the above formula (2).

[Layer configuration of first and second light diffusion plates]
The first and second light diffusion plates 30 ₁ and 30 ₂ may be single-layer plates made of a single transparent material, or may have a multilayer structure in which layers made of different transparent materials are laminated. A multilayer board may be sufficient. When the first and second light diffusion plates 30 ₁ and 30 ₂ are multilayer plates, one or both sides of the first and second light diffusion plates 30 ₁ and 30 ₂ are usually 10 μm to 200 μm, preferably 20 μm to It is preferable to use a structure in which a skin layer having a thickness of 100 μm is formed, and a transparent resin material constituting the skin layer to which an ultraviolet absorber is added is used. By adopting such a configuration, it is possible to prevent the first and second light diffusing plates 30 ₁ and 30 ₂ from being deteriorated by the point light source 22 and ultraviolet rays that may be included in light from the outside, and in particular, point-like. If the proportion of the light source 22 of ultraviolet rays using a relatively large, because it can prevent deterioration due to ultraviolet rays, it is preferable that the lower surface 31 _1, 31 ₂ in the skin layer is formed, this time the upper surface 32 ₁ , 32 ₂ is not formed is skin layer to further preferred in terms of cost. When the transparent resin material constituting the skin layer is added with an ultraviolet absorber, the content is usually 0.5% by mass to 5% by mass, preferably 1% by mass to 2% based on the transparent resin material. 0.5% by mass.

The first and second light diffusion plates 30 ₁ and 30 ₂ 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.

[Constituent materials]
The first and second light diffusion plates 30 ₁ and 30 ₂ are made of a transparent material. The refractive index of the transparent material is usually 1.56 to 1.62. Examples of the transparent material include a transparent resin material and a transparent glass material. Examples of the transparent resin material include polycarbonate resin (refractive index: 1.59), MS resin (methyl methacrylate-styrene copolymer resin) (refractive index: 1.56-1.59), polystyrene resin (refractive index: 1.59), AS resin (acrylonitrile-styrene copolymer resin) (refractive index: 1.56-1.59), etc. Polystyrene resin is preferable in terms of surface and moisture absorption.

  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.

  Examples of UV absorbers include benzotriazole UV absorbers, benzophenone meter UV absorbers, cyanoacrylate UV absorbers, malonic ester UV absorbers, oxalic anilide UV absorbers, and triazine UV absorbers. Preferred are benzotriazole ultraviolet absorbers and triazine ultraviolet absorbers.

  The transparent resin material is usually used without adding a light diffusing agent as an additive, but may be added with a light diffusing agent as long as it is a slight amount that does not impair the object of the present invention.

As the light diffusing agent, a powder having a refractive index different from that of the above-described transparent material mainly constituting the first and second light diffusing plates 30 ₁ and 30 ₂ is usually used and dispersed in the transparent material. Used. As the light diffusing agent, for example, organic particles such as styrene resin particles and methacrylic resin particles, inorganic particles such as potassium carbonate particles, silica particles, and silicone resin particles are used, and the particle diameter is usually 0.8 μm to 50 μm. .

  Further, the surface on the point light source 22 side can be a surface having light diffusibility in order to reduce moire. For example, the surface on the point light source 22 side may be constituted by a skin layer containing fine particles called a matting agent, or the surface on the point light source 22 side may be embossed or blasted, A matting layer may be formed by applying a coating solution containing a matting agent and a binder.

[Method of manufacturing first and second light diffusing plates]
The first and second light diffusion plates 30 ₁ and 30 ₂ can be manufactured by, for example, a method of cutting out from a transparent material. Moreover, when using a transparent resin material as a transparent material, it can manufacture by normal methods, such as an injection molding method, an extrusion molding method, a photopolymer method, a press molding method, for example.

[Disposition relationship of first and second light diffusion plates]
The first and second light diffusion plates 30 ₁ and 30 ₂ are sequentially provided in the z direction. First and second light diffusing plate ₃₀ 1, 30 ₂ includes a convex portion 33 ₁ in the extending direction (Y1 direction), the convex portion 33 ₂ in the extending direction (X2 direction) Togaryaku to orthogonal Is arranged. The angle formed between the extending direction of the convex portion 33 ₁ of the extending direction and the convex portion 33 _2, 80 ° to 100 ° is illustrated, preferably, 90 °.

The distance _{d 12} between the first and second light diffusing plate ₃₀ 1, 30 _2, first light diffusing plate 30 ₁ of the convex portion 33 ₁ apex 33b ₁ and the second light diffusion plate 30 ₂ a z-direction distance between the lower surface 31 _2, 5 mm or less can be exemplified. From the viewpoint of the light diffusing plate unit 21 as compact _{as, d 12} is 0 mm, the first convex portion 33 ₁ of the light diffusing plate 30 ₁ and the second and the lower surface 31 ₂ of the light diffusion plate 30 ₂ You may arrange | position so that it may contact | connect. Thus, in the case of providing in contact with the second light diffusion plate 30 ₂ to the first on the light diffusing plate 30 _1, a second thickness d2 of the light diffusion plate 30 ₂ first light diffusing plate it is preferable to use a thinner than 30 ₁ of the thickness d1. For example, since the second light diffusion plate 30 ₂ If assumed thinner such film form, can be used first light diffusing plate 30 ₁ as the second support bars of the light diffusion plate 30 _2.

[Arrangement of light diffuser unit]
Light diffusing plate unit 21 having a light diffuser 30 _1, 30 ₂ first and second of the above configuration, the distance D from the point light sources 22 to the lower surface 31 of the _first light diffuser 30 _1, usually It arrange | positions with respect to the point light source 22 so that it may become 3 mm-50 mm. In the transmissive image display device 1 or the surface light source device 20, Lx, Ly, and D are values in which Lx / D and Ly / D are each 2 or more, and further 2.5 or more. Is preferable in that it can be made thinner.

Also, the light diffusing plate unit 21, in the transmissive image display device 1, to the extending direction of the convex portion 33 ₁ may be arranged such that the longitudinal direction of the screen, arranged so as to be laterally May be.

If the first light diffusion plate 30 ₁ of the convex portion 33 ₁ in the extending direction (Y1 direction) is arranged a light diffusing plate unit 21 so that the horizontal direction of the screen, the second light diffusion plate 30 ₂ convex portion 33 ₂ in the extending direction (X2 direction) is the longitudinal direction of the screen. In such an arrangement, the ratio of the more suppressing brightness unevenness when viewed from an oblique lateral direction, and h _a and w _a in equation (2) showing the convex portion 33 ₂ of the contour [R ₂ = h _a / w _a] is preferably smaller than the ratio of h _a and w _a [R ₁ = h _a / w _a] in equation (2) showing the convex portion 33 ₁ of the contour shape, k _a in the formula (2) showing the convex portion 33 ₂ of the contour is preferably smaller than k _a in equation (2) showing the convex portion 33 ₁ of the contour. More preferably, in the arrangement of the point light sources 22 in the transmissive image display device 1, the interval Lx between the point light sources 22 in the vertical direction of the screen is equal to or greater than the interval Ly between the point light sources 22 in the horizontal direction. It ’s big.

When the first light diffusing plate 30 ₁ of the convex portion 33 ₁ in the extending direction (Y1 direction) to position the light diffusing plate unit 21 so that the longitudinal direction of the screen, the second light diffusion plate 30 _{and second} convex Jo portion 33 ₂ in the extending direction (X2 direction) is the horizontal direction of the screen. In such an arrangement, the ratio of the more suppressing brightness unevenness when viewed from an oblique lateral direction, and h _a and w _a in equation (2) showing the convex portion 33 ₁ of the contour [R ₁ = h _a / w _a] is preferably smaller than the ratio of h _a and w _a [R ₂ = h _a / w _a] in equation (2) showing the convex portion 33 ₂ of the contour shape, k _a in the formula (2) showing the convex portion 33 ₁ of the contour shape is preferably smaller than k _a in equation (2) showing the convex portion 33 ₂ of the contour. More preferably, in the arrangement of the point light sources 22 in the transmissive image display device 1, the interval Lx between the point light sources 22 in the vertical direction of the screen is equal to or greater than the interval Ly between the point light sources 22 in the horizontal direction. It ’s big.

  Next, the function and effect of the light diffusing plate unit 21 will be described by taking as an example the case where the light diffusing plate unit 21 is applied to the transmissive image display device 1 as shown in FIG. Here, it is assumed that the X1 direction and the X2 direction are parallel to the x direction, and the Y1 direction and the Y2 direction are parallel to the y direction.

Since the first and second light diffusing plates 30 ₁ and 30 ₂ of the light diffusing plate unit 21 have convex portions 33 ₁ and 33 ₂ formed on the upper surfaces 32 ₁ and 32 ₂ , The light can be converted into linear light having a substantially uniform luminance distribution. In the light diffusing plate unit 21, the first and second light diffusing plates 30 ₁ and 30 ₂ are arranged such that the convex portions 33 ₁ and 33 ₂ are substantially orthogonal to each other. As a result, light from the plurality of point light sources 22 is converted into planar light by the light diffusion plate unit 21. Further, the first and second light diffusing plates 30 ₁ and 30 ₂ respectively convert the light from the point light source 22 into linear light having substantially uniform luminance in the extending direction. It has become. Therefore, since the light from the plurality of point light sources 22 is uniformly dispersed by the light diffusing plate unit 21, it is possible to generate planar light having higher luminance uniformity on the surface orthogonal to the z direction.

  Since the surface light source device 20 includes the light diffusing plate unit 21, the surface light having a higher luminance uniformity on the surface orthogonal to the z direction in which the light from the plurality of point light sources 22 is uniformly dispersed. Can be emitted. Further, since the transmissive image display device 1 includes the light diffusing plate unit 21, light from a plurality of point light sources 22 is uniformly dispersed, and the luminance uniformity on the surface orthogonal to the z direction is higher. It is possible to irradiate the transmissive image display unit 10 with planar light. As a result, a higher quality image can be displayed.

As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment. In the above embodiment, the arrangement example of the plurality of point light sources 22 is shown in FIGS. 3 and 4. For example, a square lattice, that is, between the point light sources 22 adjacent to each other in the x direction and the y direction as described above. The interval may be the same. In addition, the end 33a _i in the cross-sectional shape of the adjacent convex portion 33 _i (i is 1 or 2) has been described as overlapping in the arrangement direction of the convex portions 33a _i , but the adjacent convex portion 33 _i (i it may be slightly flattened portions (e.g., the extent caused by manufacturing error ones) has not occurred, such as between the ends 33a _i of 1 or 2). The light diffusing plate unit 21 may further include an optical film such as a diffusing film or a microlens film on the transmissive liquid crystal display unit 10 side (for example, the liquid crystal panel side). Further, the transmissive image display device 1 may further include an optical film such as the above-described diffusion film or microlens film between the light diffusing plate unit 21 and the transmissive liquid crystal display unit 10.

  Furthermore, the surface light source device 20 and the transmissive image display device 1 may include a reflection unit such as a reflection plate that reflects the light output from the point light source 22 toward the light control plate unit 21 side. In the schematic diagram shown in FIG. 1, the reflecting means may be provided on the side opposite to the light diffusing plate unit (light control plate unit) 21 with respect to the point light source 22, for example, to hold the point light source 22. The light source mounting surface of the holding member can be a reflective surface.

Further, the first and second light control plates have been described as the first and second light diffusion plates 30 ₁ and 30 ₂ as an example, but the first and second light control plates transmit light in various directions. convex portion 33 ₁ and the convex portion 33 ₂ for dispersing the light by deflecting also said that deflecting plate formed on the exit surface side. The first and second light control plate, in order to more evenly disperse the light output from the plurality of point light sources to generate a linear light, the convex portion 33 ₁ and convex on the emission side of the light Jo portion 33 ₂ may if the shaped plate-like optical components. In this case, the light control plate unit can be assumed that two of the optical components, the convex portion 33 ₁ and the convex portion 33 ₂ are arranged to be substantially perpendicular to the respective extending direction. In addition, although demonstrated as plate shape, the thing of a film form and a sheet form is also included according to thickness.

DESCRIPTION OF SYMBOLS 1 ... Transmission type image display apparatus, 10 ... Transmission type image display part, 20 ... Surface light source device, 21 ... Light diffusing plate unit (light control board unit), 22 ... Point light source, 33a ₁ ... End of convex-shaped part ( End of the convex portion of the first light control plate), 33a ₂ ... End of the convex portion (end of the convex portion of the second light control plate), 33a _i ... End of the convex portion (first and first) End of the convex portion of the second light control plate), 33 _i ... Convex portion (convex portion of the first and second light control plates), 30 ₁ ... First light diffusion plate (first light control) Plate), 30 ₂ ... second light diffusion plate (second light control plate), 31 ₁ ... lower surface of the first light diffusion plate (first surface of the first light control plate), 31 ₂ ... first Lower surface of the second light diffusion plate (first surface of the second light control plate), 32 ₁ ... Upper surface of the first light diffusion plate (second surface of the first light control plate), 32 ₂ . The upper surface of the second light diffusion plate (the second surface of the second light control plate , 33 i _... convex portion (convex portion of the first and second light control plate), 33 1 _... convex portion of the first light diffusing plate (the convex portion of the first light control plate), 33 ₂ ... convex portion of the second light diffusion plate (convex portion of the second light control plate), Y1 ... extension direction of the convex portion of the first light control plate, X1 ... substantially orthogonal to the Y1 direction Direction, X2... Extension direction of the convex portion of the second light control plate, Y2... Direction substantially orthogonal to the X2 direction.

Claims (4)

Light incident from the first surface can be emitted from the second surface located on the opposite side of the first surface, and extends in one direction and is substantially perpendicular to the one direction. A plurality of convex portions arranged in parallel are provided with first and second light control plates formed on the second surface,
The second light control plate is provided on the first light control plate;
The first surface of the second light control plate is located on the second surface side of the first light control plate;
The extending direction of the convex portion included in the first light control plate and the extending direction of the convex portion included in the second light control plate are substantially orthogonal to each other.
Each of the convex portions of the first and second light control plates passes through both ends in a cross section orthogonal to the extending direction of each of the convex portions of the first and second light control plates. An axis is a u-axis, and an axis that passes through the center between the both ends on the u-axis and is orthogonal to the u-axis is a v-axis, and for each of the convex portions of the first and second light control plates, When the length in the u-axis direction is w _a , the contour shape of each of the convex portions of the first and second light control plates in the cross section is −0.475 w _a ≦ u ≦ 0.475 w. light control plate unit which is characterized by being represented by v (u) satisfying the following formula (1) in _a.

However, in the formula (1),

(In the formula (2), _{h a} is a constant satisfying the following 0.40 W _a or 1.60 W _{a, k a} is a constant satisfying -1.00 or more and -0.15 or less)   The light control plate unit according to claim 1, wherein the first surface of each of the first and second light control plates is substantially flat. The light control plate unit according to claim 1 or 2,
A plurality of point light sources which are provided on the first light control plate side of the light control plate unit and supply light to the first surface of the first light control plate;
A surface light source device comprising: The light control plate unit according to claim 1 or 2,
A plurality of point light sources for supplying light to the light control plate unit;
A transmissive image display unit that is provided on the second light control plate of the light control plate unit and that is irradiated with light emitted from the light control plate unit to display an image;
A transmissive image display device comprising:

Images