JP2011013631A - Deflection structure plate, surface light source device, and direct image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deflection structure plate which is applicable to light from a point light source, and suppresses luminance unevenness, and further to provide a surface light source device and a direct image display device.SOLUTION: The deflection structure plate 1 includes: first projection parts 10 which extend in a first direction and are arranged in parallel in a second direction on a first main surface 1a; and a second projection parts 20 which extend in a second direction and are arranged in parallel in the first direction on a second main surface 1b. A prism part which is the first projection part has flanks 13a, 13b and in the cross section of the prism part, each flank has an angle which is formed by the flank and normal directions of the two main surfaces 1a, 1b and becomes smaller on the hem side of the prism than the top end part side of the prism part. The vertex angle of the prism part is an angle with which at least a part of light incident on the top end of the prism part from the light source is totally reflected to an emission surface side in the prism part when the prism part is located on a center between two adjoining light sources. Further each second projection part 20 is constituted of a curved surface which intersects a plate thickness direction.

Description

  The present invention relates to a deflection structure plate, a surface light source device, and a direct type image display device.

  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. For example, as shown in FIG. 10, a direct image display device (102) in which a light source (105) is arranged on the back side of the transmissive image display unit 4 is widely used. The transmissive image display unit 4 is a liquid crystal display panel, and linear deflection plates (4B, 4C) are arranged on both surfaces of the liquid crystal cell (4A). The light source (105) is a linear light source such as a straight tube type cold cathode ray tube. A plurality of light sources (105) are used in parallel with each other.

  In the direct type image display device (102), it is desirable that the light from the light source (105) can be uniformly dispersed to uniformly illuminate the transmissive image display unit (4). For this reason, in the direct type image display device (102), the deflection structure plate (101) is disposed between the light source (105) and the transmissive image display unit (4). The deflection structure plate (101) has a function of changing the direction of light incident from the light source side (105) and emitting it from the opposite side of the transmissive image display unit (4) side.

  FIG. 11 is a diagram schematically illustrating an example of a conventional deflection structure plate. In the conventional deflection structure plate (101) shown in FIG. 11, a plurality of convex portions (110) are formed on the main surface (101a) on the light source (105) side and the main surface (101b) on the transmissive image display unit (4) side. 120). Further, the side surfaces of the convex portions (110, 120) are formed as a flat surface, and the plurality of convex portions (110, 120) have a triangular cross-sectional shape. The plurality of convex portions (110, 120) extend in one direction, and extend in the x direction shown in FIG. 8 on the main surface (101a) on the light source (105) side, and the transmissive image display portion (4). The main surface (101b) on the side extends in the y direction shown in FIG. 11 (see, for example, Patent Document 1).

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 deflection structure 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 of occurrence of luminance unevenness in which brightness differs between the vicinity of the point light source and the position away from the point light source.

  The present invention has been made to solve such a problem, and is applicable to light from a point light source, and can be applied to a deflection structure plate, a surface light source device, and a direct type that can suppress luminance unevenness. An object is to provide an image display device.

  The deflecting structure plate according to the present invention is a deflecting structure plate that has a plate shape and emits light incident from the first main surface from the second main surface facing the first main surface, and extends in the first direction. A plurality of first convex portions formed on the first main surface, and extending in a second direction substantially orthogonal to the first direction, and formed on the second main surface. A plurality of second convex portions, and the plurality of first convex portions are a plurality of prism portions arranged in parallel in the second direction, and each of the plurality of prism portions has two main surfaces. Has a pair of side surfaces that are smaller than the tip end side of the prism portion on the skirt side of the prism portion, and the prism apex angle of the prism portion formed by the pair of side surfaces is When the prism part is located on the center part between two adjacent light sources, the light from the light source incident on the tip part of the prism part The angle is such that at least a part of the prism part is totally reflected to the exit surface side, the plurality of second convex parts are arranged in parallel in the first direction, and each second convex part has a plate thickness. It is characterized by comprising a curved surface that intersects the direction.

  In the above configuration, the light incident from the first main surface is emitted from the second main surface. In this case, the light is incident on the deflecting structure plate via the plurality of first convex portions formed on the first main surface, and passes through the plurality of second convex portions formed on the second main surface. Emitted. Since the extending direction of the first convex portion and the extending direction of the second convex portion are substantially orthogonal, for example, even if a point light source is arranged on the first main surface side, it is emitted as planar light can do. In addition, since the surface of the second convex portion is configured as a curved surface, light is deflected in various directions according to the passing position by refraction when passing through the curved surface. As a result, the light can be sufficiently uniformly dispersed by passing through the deflecting structure plate, so that luminance unevenness can be suppressed. Thus, the deflection structure plate can be applied to a point light source, and even the light output from the point light source can be sufficiently uniformly dispersed.

  In the above configuration, light emitted from the plurality of light sources is mainly incident on the deflection structure plate through the prism portion of the first convex portion. When light from two adjacent light sources out of the plurality of light sources is incident on the prism portion near the central portion of the two adjacent light sources, the light from the tip end side of the pair of side surfaces of the prism portion. A lot of light is incident. At this time, since the incident angle of the light on the side surface is smaller than the incident angle in the case of a flat surface having no prism portion on the opposite side to the emitting surface, for example, the transmittance at the time of incidence is larger. Furthermore, the light incident on the tip is directed toward the exit surface by total reflection. Therefore, it is possible to increase the amount of light emitted from the deflection structure plate in the vicinity of the central portion by efficiently using the light propagating in the vicinity of the central portion of the two adjacent light sources.

  On the other hand, on the light source, the light propagates in a direction parallel to the normal line of the emission surface, so that the light reaches almost the entire side surface of the prism portion. In the above configuration, since the angle formed between the side surface and the normal direction of the exit surface is smaller on the skirt side of the prism portion than on the tip portion side, for example, the side surface of the prism portion is the tip with respect to the normal direction. The transmittance at the time of incidence of light on the skirt side of the prism part is reduced as compared with the case where the plane is uniformly inclined at the same angle as the part side. Therefore, the amount of light emitted from the area of the deflection structure plate near the light source is suppressed.

  As described above, the amount of light emitted from the deflection structure plate is increased in the vicinity of the central portion of the two adjacent light sources, while the amount of light emitted from the deflection structure plate is reduced in the vicinity of the light source. Luminance unevenness on the exit surface of the deflection structure plate can be suppressed. And in the deflection | deviation structure board which concerns on this invention, since each prism part has the said structure, a brightness nonuniformity can be suppressed hardly depending on the position of the deflection | deviation structure board with respect to a light source. Therefore, the luminance unevenness can be more stably suppressed.

  In addition, each of the pair of side surfaces of the first convex portion has a first plane portion located on the tip portion side and a second plane portion located on the skirt side, and the deflection structure plate has a second plane portion. The angle formed by the plane portion and the plate thickness direction is smaller than the angle formed by the first plane portion and the plate thickness direction, and the prism apex angle is a central portion between two adjacent light sources of the plurality of light sources. When positioned above, at least part of the light from the light source incident on the first flat surface portion of one side surface of the pair of side surfaces is entirely exposed to the emission surface side at the first flat surface portion of the other side surface. It is good also as a structure which is an angle reflected. Moreover, the structure which the light totally reflected by the 1st convex-shaped part propagates in a plate | board thickness direction is preferable.

  In the deflection structure plate according to the present invention, the first convex portion and the second convex portion may be convex toward the outside.

（ただし、Ｚは第二凸状部の断面における頂点を原点としたときの板厚方向の位置、Ｗは、その頂点を原点としたときの第１の方向の位置、ｋ_ｂは−１≦ｋ_ｂ＜１である定数、ｗ_ｂは、第二凸状部の幅、ｈ_ｂは、第二凸状部の高さである。）によって示される形状であることが好ましい。 Furthermore, in the deflection structure plate according to the present invention, the second convex portion has a cross-sectional outline perpendicular to the second direction expressed by the following formula (1).

(However, Z is the position in the thickness direction when the vertex in the cross section of the second convex portion is the origin, W is the position in the first direction when the vertex is the origin, and _kb is −1 ≦ It is preferable that the constant is k _b <1, w _b is the width of the second convex portion, and h _b is the height of the second convex portion.

In this case, it is preferable that the ratio of the height h _b and the width w _b (h _b / w _b ) of the second convex portion is 0.2 to 1. The second convex portion, it is preferable that the ratio between the height _{h b} and width _{w b (h b / w b} ) is 0.4 to 0.8. The second convex portion is preferably constant _{k b} is -0.75～ + 0.75. Further, the second convex portion is preferably constant _{k b} is -0.75～ + 0.25.

  A surface light source device according to the present invention is provided on a plurality of point light sources arranged in a discrete manner and a plurality of point light sources, and is irradiated with light from the plurality of point light sources. And a deflection structure plate.

  As described above, in the deflecting structure plate according to the present invention, light from a point light source can be converted into planar light, and at that time, the light from the point light source can be dispersed sufficiently uniformly. Is possible. According to the configuration of the surface light source device, since the light from the point light source is emitted through the deflection structure plate, the light from the point light source can be emitted with sufficiently uniform dispersion. As a result, it is possible to emit planar light with suppressed luminance unevenness.

  Further, a direct image display device according to the present invention is provided with a plurality of point light sources arranged discretely and a plurality of point light sources, and a book irradiated with light from the plurality of point light sources. And a transmissive image display unit that is provided on the deflection structure plate and irradiated with light transmitted through the deflection structure plate.

  As described above, in the deflecting structure plate according to the present invention, light from a point light source can be converted into planar light, and at that time, the light from the point light source can be dispersed sufficiently uniformly. Is possible. According to the configuration of the direct type image display device, since the light from the point light source is emitted through the deflection structure plate, the light from the point light source can be emitted sufficiently uniformly. Therefore, in the direct type image display device according to the present invention, the transmissive image display unit can be irradiated with sufficiently uniformly dispersed light, so that it is possible to display an image in which luminance unevenness is suppressed.

  The deflection structure plate of the present invention can sufficiently uniformly disperse light from a point light source. Accordingly, when this deflection structure is used in a surface light source device in combination with a point light source, it is possible to generate planar light in which light from the point light source is sufficiently uniformly dispersed. Further, when the deflection structure plate is used in a direct image display device in combination with a point light source, the image displayed by the transmissive image display unit is displayed with uniform brightness regardless of the position of the point light source. Can do. As described above, according to the present invention, it is possible to provide a deflection structure plate that can be applied to a point light source and can suppress unevenness in luminance, a surface light source device including the same, and a direct-type image display device.

It is a perspective view showing typically one embodiment of a deflection structure board concerning the present invention. It is drawing which shows the cross-sectional shape orthogonal to the 1st direction of the deflection | deviation structure board shown in FIG. It is drawing which shows the cross-sectional shape orthogonal to the 1st direction of a 1st convex-shaped part. It is drawing for demonstrating the conditions which a prism apex angle satisfy | fills. It is drawing for demonstrating the conditions which a prism base angle satisfy | fills. It is a figure which shows the cross-sectional shape orthogonal to the 2nd direction of the deflection | deviation structure board shown in FIG. It is a figure which shows typically an example of the direct type image display apparatus provided with the deflection | deviation structure board shown in FIG. It is drawing which shows typically the path | route after incidence | injection of the light to the prism part on the center part between 2 adjacent light sources, and after incidence | injection. It is drawing which shows typically the path | route after incidence | injection of the light to the prism part on a light source, and incident. It is a figure which shows typically an example of the direct type | mold image display apparatus using the conventional deflection | deviation structure board. It is a perspective view which shows typically an example of the conventional deflection | deviation structure board.

  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 equivalent element, and the overlapping description is abbreviate | omitted. Further, the dimensional ratios in the drawings do not necessarily match those described.

  FIG. 1 is a perspective view schematically showing an embodiment of a deflection structure plate according to the present invention. The deflection structure plate 1 is a plate-like body capable of transmitting light and uniformly disperses light. Examples of the plan view shape of the deflection structure plate 1 include a rectangular shape such as a rectangle or a square. In the deflection structure plate 1, one main surface is a first main surface 1a and the other main surface is a second main surface 1b. The light incident from the first main surface 1a is emitted from the second main surface 1b on the opposite side.

  As shown in FIG. 1, a plurality of first convex portions 10 are formed on the first main surface 1a of the deflection structure plate 1, and a second convex portion 20 is formed on the second main surface 1b. Has been. The first convex portion 10 and the second convex portion 20 are convex on the opposite sides, that is, outward. Moreover, the 1st convex part 10 and the 2nd convex part 20 are extended in the mutually different direction. The extending direction of the first convex portion 10 and the extending direction of the second convex portion 20 intersect each other at substantially right angles, specifically, 80 ° to 100 °, preferably 85 ° to 95 °. They intersect at an angle range, ideally at an angle of 90 °. In this specification, the extending direction of the first convex portion 10 is also referred to as an x direction (first direction), and the extending direction of the second convex portion 20 is also referred to as a y direction (second direction). The thickness direction of the deflection structure plate 1 is also referred to as the z direction.

[First convex part]
FIG. 2 is a cross-sectional view of the deflection structure plate cut in a direction perpendicular to the extending direction of the first convex portion.

  The plurality of first convex portions 10 are formed in parallel in the y direction. The adjacent first convex portions 10, 10 are in contact with each other. That is, the ends 11 of the adjacent first convex portions 10 and 10 are at the same position in the y direction. In this structure, the 1st groove part extended in the x direction which makes the end 11 the bottom part is formed between the adjacent 1st convex-shaped parts 10 and 10. As shown in FIG. Each of the plurality of first convex portions 10 has the same cross-sectional shape, and the cross-sectional shape of each first convex portion 10 is uniform in the extending direction (x direction).

  Each first convex portion 10 has a vertex 12 below in the cross-sectional shape shown in FIG. The vertex 12 is located at the center between the ends 11 and 11 in the y direction.

The width w _a of the first convex portion 10 indicates the distance in the y direction between both ends 11 of the first convex portion 10. Width _{w a} is 40μm~800μm, preferably 80μm~400μm.

  The cross-sectional shape of each first convex portion 10 orthogonal to the extending direction of each first convex portion 10 is substantially the same among the plurality of first convex portions 10, for example, in a sawtooth shape as shown in FIG. is there. And the prism top part 12 of the 1st convex part of each 1st convex part 10 is located on the same plane (virtual plane). When the first convex portions 10 that are convex on the point light source 5 side are formed as in the present embodiment, the separation distance D between the deflecting structure plate 1 and the plurality of point light sources 5 is the first distance. The distance between the plane including the prism top 12 of the convex portion 10 and the plane on which the plurality of point light sources 5 are arranged. 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 adjacent two point light sources 5, is 2 or more, preferably 2.5 or more. The

  FIG. 3 is a schematic configuration diagram of the first convex portion 10 and shows an enlarged view of one first convex portion 10. The configuration of the first convex portion 10 shown in FIG. 3 is when viewed along the extending direction of the first convex portion 10, in other words, when viewed from the direction in which the cross-sectional shape orthogonal to the extending direction is shown. It is the composition.

  The first convex portion 10 has a prism shape tapered toward the opposite side to the second main surface 1b, and has a pair of side surfaces 13a and 13b. The side surfaces 13 a and 13 b are incident surfaces for light from the point light source 5. Further, the pair of side surfaces 13 a and 13 b are symmetrical with respect to a straight line in the plate thickness direction passing through the prism top portion 12 of the first convex portion 10.

As shown in FIG. 3, each of the side surfaces 13a and 13b has a first region 13a ₁ , 13b ₁ , a second region 13a ₂ , 13b _2, and a third region 13a ₃ , in order from the prism top 12 side to the skirt side. having 13b _3. Each of the regions 13a ₁ , 13b ₁ , 13a ₂ , 13b ₂ , 13a ₃ , 13b ₃ is a substantially flat surface, and the angles β ₁ , β ₂ , β ₃ made by the z-axis direction with each of the regions 13a ₁ , 13b ₁ , 13b ₂ , 13b ₃ , 13b ₃ The shape portion 10 becomes smaller from the tip side to the skirt side. That is, the side surfaces 13a and 13b of the first convex portion 10 are steeper on the skirt side.

The prism top portion 12 is formed by the first regions 13a ₁ and 13b ₁ of each of the pair of side surfaces 13a and 13b, and the angle α formed by the pair of first regions 13a ₁ and 13b ₁ is the prism apex angle. . Further, the angle γ between the third regions 13a ₃ and 13b ₃ of the side surfaces 13a and 13b and the y-axis direction is the prism base angle of the first convex portion 10. In this case, β ₁ = 0.5α and β ₃ = 0.5π−γ.

The condition that the prism apex angle α is satisfied will be described with reference to FIG. FIG. 4 is an enlarged schematic view of the vicinity of the tip of the first convex portion 10 (region A surrounded by a chain line in FIG. 3). In FIG. 3, the light source 31 on the side closer to the one side surface 13a of the first convex portion 10 is shown for convenience.

The prism apex angle α is such that the light F from the light source 5 closer to the side surface 13a is the first region when the first convex portion 10 is positioned on the central portion between the adjacent two light sources 5 and 5. When entering the 13a _1, which is defined angle to be totally reflected in the plate thickness direction by the first region 13b ₁ of the other side surface 13b. That is, the refractive index of the material constituting the first convex portion 10 is n, the incident-side refractive index is n _0, and the first region 13a ₁ of the light F from the center position of the light source 5 as shown in FIG. When the distance in the y-axis direction to the incident position is approximately L / 2 and the distance in the z-axis direction is approximately D, the prism apex angle α is an angle that satisfies the following formula (2). .

Normally, since the medium between the deflecting structure plate 1 and the light source 5 is air, n ₀ = 1. Also in this embodiment, n ₀ = 1 unless otherwise specified. As described above, when the prism apex angle α is defined, it is assumed that the first convex portion 10 is located on the central portion between the adjacent two light sources 5 and 5. Therefore, strictly speaking, the distance in the y-axis direction between the prism top 12 and the light source 5 is L / 2, and the distance in the z-axis direction between the prism top 12 and the light source 5 is D. However, the size of the first convex portion 10, particularly the size in the vicinity of the prism top portion 12, is smaller than those of L and D. Therefore, as shown in FIG. 4 and as understood from the above formula (2), the distances of the light F incident position on the _first region 13a ₁ from the light source 5 in the y-axis direction and the z-axis direction are expressed as L. Even when expressed as / 2 and D, the error is in a negligible range.

  Next, the condition that the prism base angle γ is satisfied will be described with reference to FIG. FIG. 5 is an enlarged schematic view of the vicinity of the bottom of the first convex portion 10 shown in FIG. 3 (region B surrounded by the two-dot chain line shown in FIG. 3). The condition satisfied by the prism base angle γ is to reduce the luminance of light emitted from the deflecting structure plate 1 in the vicinity immediately above the light source 5, and the prism base angle γ travels in a direction parallel to the z axis. The transmittance T when the incoming light F is incident on the first convex portion 10 is an angle at which the transmittance T is about 70% or less. This will be described in more detail.

ただし、δ、ｔ_ｓ、ｔ_ｐは、以下の式（４），式（５），式（６）を満たす。

As shown in FIG. 5, the light emitted F propagated through in a direction parallel to the z axis is incident on the third first convex portion 10 through the region 13a ₃ to the first convex portion 10 Let δ be the emission angle when Also, the s-polarized light transmission amplitude coefficient and p-polarized light transmission amplitude coefficient at incident light F t _{s, respectively,} and t _p. At this time, the prism base angle γ satisfies the following relational expression (3).

However, _[delta], t s, _{t p,} the following equation (4), Equation (5), satisfies the equation (6).

The first convex portion 10 shown in FIG. 3 is represented by the above formula (2) and formulas (3) to (6), and the prism tops are set so as to satisfy the conditions described using FIG. 4 and FIG. It has an angle α and a prism base angle γ. In other words, the first regions 13a ₁ and 13b ₁ and the third regions 13a ₃ and 13b ₃ have a prism apex angle α and a prism base angle γ with respect to the y-axis direction (or z-axis direction). The second regions 13a ₂ and 13b ₂ are formed so as to be inclined and connect the first regions 13a ₁ and 13b ₁ and the third regions 13a ₃ and 13b ₃ . Then, when the conditions of the prism apex angle α and the prism base angle γ are satisfied, as shown in FIG. 3, the third region 13a ₃ is formed from the angle β ₁ formed by the z-axis direction and the first regions 13a ₁ and 13b _1. , 13b ₃ is smaller in angle β ₃ . That is, the planar third regions 13a ₃ and 13b ₃ are steeper than the planar first regions 13a ₁ and 13b ₁ .

Examples of the angles β ₁ , β ₂ , and β ₃ include 30 °, 20 °, and 10 °. Further, the y-axis direction length of the first region 13a ₁ second regions 13a ₂ and the third region 13a ₃ as shown in FIG. 3, in particular, the length obtained by projecting the respective regions in the y-axis direction is when was the _{y 1, y 2, y 3} , y 1, y 2, y 3 , for example, 20 [mu] m, 15 [mu] m, is 12.5 .mu.m. Alternatively, y ₁ , y ₂ , and y ₃ are, for example, 25 μm, 12.5 μm, and 10 μm. Although the side surface 13a side has been described here, the same applies to the side surface 13b.

The deflection structure plate 1 can be manufactured as follows, for example. First, L / D is set to a desired value (for example, 3.5) in advance, and the prism apex angle α and the prism base angle β are set so as to satisfy Expression (2) and Expressions (3) to (6). Stipulate. As a result, the angle formed by the planar first and third regions 13a ₁ , 13b ₁ , 13a ₃ , 13b ₃ and the z-axis direction is defined. The lengths y ₁ and y ₃ of the first and third regions 13a ₁ , 13b ₁ , 13a ₃ and 13b _{3 in} the y-axis direction (or the length in the z-axis direction) depend on the size of the deflection structure plate 1 To decide. Then, to design the first convex portion 10 connects the first and third regions _{13a 1,} 13b _1, 13a 3, 13b ₃ in the second region _13a 2, 13b _2. In accordance with this design, a mold is produced, and a deflection structure plate having a substantially rectangular parallelepiped shape and having a plurality of first convex portions 10 formed on one side is molded from a transparent material using the mold. . Here, the mold is used, but the first convex portion 10 having the prism apex angle and the prism base angle described above using the microfabrication technique on one end surface of a plate made of a substantially rectangular parallelepiped transparent material, for example. A plurality of may be formed.

(Second convex part)
The second convex portion will be described with reference to FIG. FIG. 6 is a cross-sectional view of the second convex portion cut in a direction perpendicular to the extending direction (y).

  The plurality of second convex portions 20 are formed in parallel in the x direction. The adjacent second convex portions 20, 20 are in contact with each other. That is, the ends 21 and 21 of the adjacent second convex portions 20 and 20 are at the same position in the x direction. In this structure, between the adjacent 2nd convex-shaped parts 20, the 2nd groove part extended in the y direction which makes the end 21 the bottom is formed. Each of the plurality of second convex portions 20 has the same cross-sectional shape, and the cross-sectional shape of each second convex portion 20 is uniform in the extending direction (y direction).

  Each 2nd convex-shaped part 20 has the vertex 22 above in the cross-sectional shape as shown in FIG. The vertex 22 is located at the center of the ends 21 and 21 in the x direction.

The height h _b of the second convex portion 20 shows a distance in the z direction between the apex 22 and the end 21. The height _{h b} is, 20μm~400μm, preferably 40Myuemu～200myuemu. The width w _b of the second convex portion 20 indicates the distance in the x direction between the ends 21 and 21. The width w _b is 40 μm to 800 μm, preferably 80 μm to 400 μm. The ratio of the height h _b to the width w _b (h _b / w _b ) is 0.2 to 1, preferably 0.4 to 0.8.

上記式（１）において、Ｚは、第二凸状部２０の断面における頂点２２を原点としたときのｚ方向の頂点２２からの距離（μｍ）を示し、Ｗは、頂点２２を原点としたときのｙ方向の頂点２２からの距離（μｍ）を示す。また、ｋ_ｂは−１≦ｋ_ｂ＜１である定数であり、通常−０．７５〜＋０．７５、好ましくは−０．７５〜＋０．２５の範囲から選択可能である。定数ｋ_ｂは、第二凸状部２０のとがり方を示すパラメータである。例えば定数ｋ_ｂが０のときは放物線となり、定数ｋ_ｂが１のときはプリズム形状となり、定数ｋ_ｂが−１のときは楕円を半分に切った形状となる。 The 2nd convex-shaped part 20 is a shape comprised so that the surface 23 which cross | intersects az direction may comprise a curved surface. As for the 2nd convex-shaped part 20, the shape by which the outline of the cross-sectional shape is shown by Formula (1) is mentioned, for example.

In the above formula (1), Z represents the distance (μm) from the vertex 22 in the z direction when the vertex 22 in the cross section of the second convex portion 20 is the origin, and W is the vertex 22 as the origin. The distance (μm) from the apex 22 in the y direction is shown. K _b is a constant satisfying −1 ≦ k _b <1, and can be selected from a range of −0.75 to +0.75, preferably −0.75 to +0.25. Constant k _b is a parameter indicative of the kurtosis way of a second convex portion 20. For example the constant k _b is the parabola 0, becomes a prism shape when the constant k _b is 1, the constant k _b is a shape cut in half ellipse when -1.

Defines the shape of the second convex portion 20, the height h _b, include those of Table 1 as an example of the value of the constant k _b in the width w _b and the formula (1).

The first convex portion 10 and the second convex portion 20 have been described above, but the first convex portion 10 formed on the light incident side is the second convex portion 20 formed on the light emission side. It is preferable to be sharper. The height h _a of the first convex portion 10 is preferably higher than the height h _b of the second convex portion 20.

The thickness h ₁ of the deflection structure plate 1 having the first convex portion 10 and the second convex portion 20 is the z direction from the vertex 12 of the first convex portion 10 to the vertex 22 of the second convex portion 20. Is the distance. The thickness _{h 1} of the deflection structure plate 1, 0.3Mm～6mm are exemplified, preferably 0.5 mm to 3 mm. The minimum thickness h ₂ of the deflection structure plate 1, the end 11 of the first convex portion 10 a z-direction distance between the end 21 of the second convex portion 20, formed on the first main surface 1a It is the distance in the z direction between the bottom of the first groove and the bottom of the second groove formed on the second main surface 2b. Minimum thickness _{h 2} of the deflection structure plate 1, 0.1 mm to 5 mm can be exemplified, preferably 0.5Mm～2.5Mm.

As the material constituting the deflecting structure plate 1, a transparent material that can transmit light without scattering inside is usually used. As a transparent material applicable to the deflection | deviation structure board 1, transparent inorganic materials, such as inorganic glass, are mentioned, for example. Moreover, as a transparent material applicable to the deflection | deviation structure board 1, the transparent resin material which is a material which is comparatively lightweight and easy to process is preferable. Examples of the transparent resin material include methacrylic resin, styrene resin, styrene-methacrylic acid copolymer resin, polycarbonate resin, cycloolefin resin, and polypropylene resin.

  The transparent material is usually used without dispersing the light diffusing agent, but the light diffusing agent may be slightly dispersed in the transparent material as long as the object of the present invention is not impaired.

  The deflection structure plate 1 shown in FIG. 1 can be manufactured, for example, by a method of cutting out from a transparent material. Moreover, when using a transparent resin material as a transparent material, it can manufacture by methods, such as an injection molding method, an extrusion molding method, a press molding method, for example.

  Next, a direct type image display device in which the deflection structure plate 1 is incorporated will be described. FIG. 7 is a schematic diagram showing an example of a direct type image display device in which the deflection structure plate shown in FIG. 1 is incorporated. In FIG. 7, a cross-sectional configuration of the direct type image display device 2 is schematically shown as an exploded view. The direct type image display device 2 includes a surface light source device 3 and a transmissive image display unit 4 disposed on the front side (front side) of the surface light source device 3.

  Examples of the transmissive image display unit 4 include a liquid crystal display panel in which linearly polarizing plates 4B and 4C are arranged on both surfaces of a liquid crystal cell 4A.

  The surface light source device 3 includes a plurality of point light sources 5 arranged on the back side of the deflection structure plate 1. Examples of the point light source 5 include a light emitting diode. The plurality of point light sources 5 are discretely arranged in the x direction and the y direction, and are used, for example, arranged at equal intervals in each direction.

  In the surface light source device 3, the deflection structure plate 1 is arranged such that the first main surface 1 a is on the point light source 5 side and the second main surface 1 b is on the transmissive image display unit 4 side.

  As shown in FIG. 7, the operation and effect of the deflection structure plate 1 will be described by taking as an example the case where the deflection structure plate 1 is incorporated in the direct type image display device 2.

  When light is output from the point light source 5, the light from the point light source 5 is deflected through the side surfaces 13 a and 13 b of the first convex portion 10 formed on the first main surface 1 a of the deflection structure plate 1. 1 is incident. The light incident on the deflection structure plate 1 travels in the deflection structure plate 1 and is emitted through the surface 23 of the second convex portion 20 formed on the second main surface 1b. In the deflection structure plate 1, the first convex portion 10 extending in the x direction and the second convex portion 20 extending in the y direction are formed so as to be substantially orthogonal to each other. The output light can be converted into planar light.

  Since the deflection structure plate 1 has the surface 23 of the second convex portion 20 configured as a curved surface, the light is deflected in various directions depending on the passing position by refraction when passing through such a curved surface. . As a result, the light from the point light source 5 passes through the deflection structure plate 1, so that the light is diffused. Due to this diffusing action, the deflecting structure plate 1 can disperse the light from the point light source 5 sufficiently uniformly, and as a result, it is possible to emit light with suppressed luminance unevenness.

  In this way, the deflection structure plate 1 adjusts the luminance unevenness by appropriately deflecting light at the time of incidence and emission, and functions as a light control plate. Further, from the viewpoint of the diffusion action as described above, the deflection structure plate 1 functions as a light diffusion plate.

  By the way, generally, in the cross section orthogonal to the x direction, the point light source 5 is closer to the point light source 5 than the region of the deflection structure plate above the point light source 5 and the vicinity thereof. For this reason, more light is likely to be incident on the deflecting structure plate. This becomes more prominent as the direct type image display device is made thinner.

  In the deflection structure plate 1 of the present embodiment, the transmittance of the deflection structure plate 1 at and near the center between the adjacent two light sources 5 and 5 by adopting the shape of the first convex portion 10. On the other hand, the transmittance of the light F with respect to the deflection structure plate 1 directly above and near the light source 5 is suppressed. This will be specifically described with reference to FIGS.

  FIG. 8 is a schematic diagram of light incident on the first convex portion 10 in the vicinity of the central portion between two adjacent light sources. FIG. 8 shows a case where the light F from the light source 5 closer to the side surface 13a is incident.

The first convex portion 10 located just above and in the vicinity of the center between the two adjacent light sources 5 and 5 is about L / 2 (mm) in the y-axis direction and about D (mm) in the z-axis direction from the light source 5. ), The light F from the light source 5 closer to the side surface 13a is inclined with respect to the z-axis direction and propagates toward the first convex portion 10. Therefore, the light F is incident on the first convex portion 10 mainly from the tip portion of the first convex portion 10. In the side surfaces 13 a and 13 b, the tip end region is the planar first region 13 a ₁ , so that the incident angle to the first convex portion 10 becomes smaller as the distance from the light source 5 increases. For example, when L / D is about 3.5 and the prism apex angle α is about 60 °, the incident angle from the light source 31 to the _first region 13a ₁ is about 0 ° as shown in FIG. Close to. Therefore, the transmittance at the time of incidence on the prism portion 42 tends to be improved.

Then, the first convex portion 10 deflecting structure plate 1 of this embodiment has the light F that has entered from the first region 13a ₁ at the distal end of the first convex portion 10, the incident side of the light F Since light is totally reflected in the y-axis direction at the first region 13b ₁ on the opposite side surface 13b, the light is directed forward. Thus, even if light diffusion occurs in the deflecting structure plate 1 as in the prior art by changing the path of the light F forward, the deflecting structure in the vicinity immediately above the center of the adjacent two light sources 5 and 5. More light F is emitted from the portion of the plate 1 to improve the luminance.

As shown in FIG. 8, there is a case where light F is incident on the second region 13a ₂ side of the first side surface 13a in the region 13a _1. In this case, the incident light is reflected by the side surface 13b opposite to the incident side and is emitted toward the second main surface 1b.

  FIG. 9 is a schematic diagram of a light beam path of light incident on the first convex portion directly above and near the light source.

As shown in FIG. 9, the light F traveling mainly along the direction parallel to the z-axis (the thickness direction of the deflecting structure plate 1) is directly above the light source 5 and in the vicinity thereof. Through the side surfaces 13a and 13b. In this case, as shown in FIG. 9, the light F that has entered the first convex portion 10 due to refraction at the time of incidence or reflection at the side opposite to the incident side is incident on the second main surface 1b side (front side). ) Therefore, the light F is emitted from the deflecting structure plate 1 also immediately above and near the light source 5. However, in the third regions 13a ₃ and 13b ₃ , the angle β ₃ made with the z-axis direction is small and steep, so that the light F is not easily incident. In addition, the third regions 13a ₃ and 13b ₃ have a transmittance of about 70% or less as described above when entering the first convex portion 10. Therefore, the amount of light F from the deflection structure plate 1 directly above and near the light source 5 is suppressed, and as a result, an increase in luminance is suppressed.

  In addition, the surface light source device 3 is configured to include the deflection structure plate 1 and the point light source 5 that irradiates light to the deflection structure plate 1, and therefore the light from the point light source 5 is deflected to the deflection structure plate 1. Thus, it can be dispersed sufficiently uniformly. Therefore, the surface light source device 3 can emit planar light in which luminance unevenness is suppressed.

  The direct type image display device 2 includes the surface light source device 3 described above and a transmissive image display unit 4 to which light emitted from the surface light source device 3 is irradiated. As described above, the surface light source device 3 can emit the surface light in which the light from the point light source 5 is sufficiently uniformly dispersed by the deflecting structure plate 1 and luminance unevenness is suppressed. Since the direct type image display device 2 illuminates the transmissive image display unit with the light emitted from the surface light source device 3, the direct type image display device 2 can display an image in which luminance unevenness is suppressed. it can.

  Although the present invention has been specifically described above based on the embodiment, the present invention is not limited to the above embodiment. For example, although the ends 11 and 11 of the adjacent first convex portions 10 are in contact with each other, between the adjacent first convex portions 10 and 10, more specifically, one of the first convex portions 10. A flat region may be formed between the end 11 and the end 11 of the other first convex portion 10. The same applies to the second convex portions 20 and 20. In addition, although the plurality of point light sources are arranged at equal intervals in the x direction and the y direction, they need not necessarily be at equal intervals.

  Further, the direct type image display device 2 may include a light diffusion plate 6 disposed between the deflection structure plate 1 and the transmission type image display unit 4 as shown in FIG. As the light diffusing plate 6, a light diffusing agent dispersed in a transparent material can be used. Moreover, what provided the fine unevenness | corrugation in the single side | surface or both surfaces of the board which consists of transparent materials can also be used. The thickness of the light diffusing plate 6 is usually 0.05 mm to 1 mm, and may be a film. By providing such a light diffusing plate 6, the light emitted from the second main surface 1 b of the deflection structure plate 1 can be further diffused to illuminate the transmissive image display unit 4 more uniformly, and the point light source 5. An image with less difference in brightness between the vicinity and other locations can be displayed.

DESCRIPTION OF SYMBOLS 1 ... Deflection structure board, 1a ... 1st main surface, 1b ... 2nd main surface, 10 ... 1st convex-shaped part (prism part), 11 ... End of y direction of 1st convex-shaped part (bottom part of 1st groove part) ), 12... Prism apex (vertex of the first convex portion), 13 a, 13 b, a pair of side surfaces of the first convex portion, 13 a ₁ , 13 b _1, first region (first flat portion), 13 a _3. , 13b ₃ ... third region (second plane part) 20 ... second convex part, 21 ... end in the x direction of the second convex part (bottom part of the second groove part), 22 ... second convex part 2 ... Direct type image display device, 3 ... Surface light source device, 4 ... Transmission type image display unit, 4A ... Liquid crystal cell, 4B, 4C ... Linear polarizing plate, 5 ... Point light source (light emitting diode), 6 ... Light diffusing plate, h ₁ ... Thickness of deflection structure plate (distance from top of first convex portion to top of second convex portion), h _2. Minimum thickness of deflection structural plate (bottom of first groove portion) Or The second groove distance to the bottom), alpha ... prism apex angle.

Claims (11)

A deflection structure plate that has a plate shape and emits light incident from the first main surface from the second main surface facing the first main surface,
A plurality of first convex portions extending in a first direction and formed on the first main surface;
A plurality of second convex portions extending in a second direction substantially orthogonal to the first direction and formed on the second main surface;
Have
The plurality of first convex portions are a plurality of prism portions arranged in parallel in the second direction,
Each of the plurality of prism portions has a pair of side surfaces whose angle formed with the normal direction of the two main surfaces is smaller than the tip end side of the prism portion on the skirt side of the prism portion,
The prism apex angle of the prism portion formed by a pair of the side surfaces is determined from the light source incident on the tip portion of the prism portion when the prism portion is located on the central portion between two adjacent light sources. An angle at which at least part of the light is totally reflected on the exit surface side in the prism portion;
The plurality of second convex portions are arranged in parallel in the first direction, and each of the second convex portions is configured by a curved surface that intersects the plate thickness direction.
A deflection structure board characterized by that.   The deflection structure plate according to claim 1, wherein each of the first convex portion and the second convex portion is convex outward. Each of the pair of side surfaces of the first convex portion is
A first planar portion located on the tip side;
A second flat portion located on the hem side;
Have
An angle formed between the second plane portion and the plate thickness direction is smaller than an angle formed between the first plane portion and the plate thickness direction,
The prism apex angle corresponds to the first plane portion on one side surface of the pair of side surfaces when the prism portion is located on a central portion between two adjacent light sources among the plurality of light sources. An angle at which at least a part of the incident light from the light source is totally reflected on the emission surface side by the first flat surface portion on the other side surface,
The deflecting structure plate according to claim 1 or 2, wherein   The deflection structure plate according to any one of claims 1 to 3, wherein the light totally reflected by the first convex portion propagates in the plate thickness direction. As for said 2nd convex part, the outline of the cross section orthogonal to said 2nd direction is following formula (1).

(Where Z is the position in the thickness direction when the vertex in the cross section of the second convex portion is the origin, W is the position in the first direction when the vertex is the origin, and k _b is −1. ≦ k _b <1 constant, w _b is the width of the second convex portion in the first direction, and h _b is the height of the second convex portion.)
The deflection structure plate according to claim 1, wherein the deflection structure plate has a shape indicated by The deflection structure plate according to claim 5, wherein the second convex portion has a ratio (h _b / w _b ) of a height h _b to a width w _b of 0.2 to 1. The deflection structure plate according to claim 5, wherein the second convex portion has a ratio (h _b / w _b ) of a height h _b to a width w _b of 0.4 to 0.8. . The second convex portion, deflecting plate according to any one of claims 5-7, wherein the constant _{k b} is characterized in that it is a -0.75～ + 0.75. The second convex portion, deflecting plate according to any one of claims 5-7, wherein the constant _{k b} is characterized in that it is a -0.75～ + 0.25. A plurality of discrete point light sources,
The deflection structure plate according to any one of claims 1 to 9, wherein the deflection structure plate is provided on the plurality of point light sources, and is irradiated with light from the plurality of point light sources.
A surface light source device comprising: A plurality of discrete point light sources,
The deflection structure plate according to any one of claims 1 to 10, wherein the deflection structure plate is provided on a plurality of the point light sources, and is irradiated with light from the plurality of point light sources.
A transmission-type image display unit provided on the deflection structure plate and irradiated with light transmitted through the deflection structure plate;
A direct-type image display device comprising:

Images