JPH0748093B2 - Surface light source element - Google Patents

Description

TECHNICAL FIELD The present invention relates to a surface light source element used in a surface light source device. The present invention is particularly preferably used as a back lighting unit of a liquid crystal display device.

[Prior Art] Conventionally, as a back lighting means for a liquid crystal display device or the like, a linear lamp is used as a light source, the lamp is placed at the focus of a rotating parabolic reflector, and a milky diffuser plate is placed above the lamp. The idea is to optimize the shape of the reflector and to adjust the diffusivity of the diffuser plate.

Also, as a special shape, a linear lamp and a light guide are combined, and the shape of the light guide is simulated by approximating a point light source.
The one that is processed into an approximate curve shape so as to collect the emitted light in a certain direction, the one that changes the thickness of the light guide along the light traveling direction, and the lenticular that changes the prism angle depending on the distance from the light source. Some are used and some are combined. If a point light source is approximated, in almost all cases, the optical path can be simulated, and the shape of the light guide layer can be changed according to the distance in the light traveling direction, and many such proposals have been made. Has been done.

In particular, recently, there is a strong demand for thinner and lighter display devices. Therefore, it is desired that the surface light source element is as thin and light as possible. In addition, the size of the display surface tends to be increased, and at the same time, improvement in brightness and uniformity of brightness are required.

[Problems to be Solved by the Invention] However, as the surface light source element, although products satisfying many required performances are required as described above,
It is still under development, and it is the present situation that nothing satisfying thinness, light weight, high brightness and uniformity has been obtained.

[Means for Solving the Problems] In view of the problems of the prior art, an object of the present invention is to use a thin (similar to the diameter of the lamp) light source as a back lighting means used in a liquid crystal display device. Another object of the present invention is to provide a surface light source device that can improve the brightness of light without increasing the wattage and have uniform brightness.

The above-mentioned object is to provide a light guide body having at least one side surface as an incident surface, a surface orthogonal to the side surface as a light emitting surface, and a reflection layer on a surface opposite to the light emitting surface, and the light guide body. In a surface light source element including a diffuser plate that diffuses light from the non-directionally, a plurality of lens units that emit light in a predetermined direction are arranged on a light emitting surface of the light guide, Each lens unit extends along the incident surface, and an outgoing light adjusting member is arranged between the light guide and the diffusion plate, and the outgoing light adjusting member is provided from the incoming surface. And a surface light source element having a light reflection pattern whose area ratio gradually decreases as the distance increases.

In the surface light source element according to the present invention as described above, the light incident from the incident surface of the light guide body is emitted from the light guide body in a state of having directionality by the lens unit, the reflection layer, and the emitted light. By the action of the adjusting member and the diffusion plate, it is possible to increase the brightness of the surface while ensuring the uniformity of the brightness on the entire surface.

Hereinafter, a surface light source element according to the present invention will be described in detail with reference to the drawings.

First, the basic idea of the surface light source element according to the present invention will be described.

The refractive index n of light in the light guide to air is generally n = 1.5 to 1.6.
In the vicinity (as shown in FIG. 7 (a)), the critical reflection angle is about 45 ° in principle when the incident end face 11 of the light guide 10 and the exit plane 12 are orthogonal (edge lighting). No light is emitted to the emission plane 12. In FIG. 7 (a), 14 is a light source such as a fluorescent lamp, 15 is its reflector, and 13 is its reflector.
Is a reflection surface formed on the emission plane 12 and the reflection side of the light guide 10.

Therefore, generally, as shown in FIG. 7B, the emission plane 12 is generally a diffusion-processed plane 12a, and the reflection surface 13 of the emission-opposing surface is a scattering reflection surface 13a.

Here, an assembly of linear convex lenses 16 of the same shape which are linear at a right angle to the traveling direction of light is formed on the emission plane, a reflecting surface 13 is formed on the opposite surface, and a fluorescent lamp is formed at one end thereof. Consider a configuration in which the linear light source 14 is arranged parallel to the line of the linear convex lens assembly. FIG. 8 (a) is a perspective view of the structure, and FIG.
FIG. 6B is a sectional view taken along the line AA '.

In such a geometrical positional relationship, the emission direction of light is 40 ° to 60 ° with respect to the normal to the direction perpendicular to the filaments of the lens, and almost no emission occurs in the normal direction (first 8 (b)).

9 (a) and 9 (b) are diagrams showing the angular distribution of the emission light luminance shown in FIG. 8 (b). That is, it is a diagram showing the ratio of the emitted light of each angle when the emitted light of the largest angle among the emitted light of each angle is 100%.

10 (a) and 10 (b) are diagrams showing the measuring method, respectively, FIG. 10 (a) is a front view of the surface light source element showing the measuring position, and FIG. It is a -A 'sectional view. In FIG. 10 (b), 40 is a luminance meter.

FIG. 9 (a) shows the angular distribution of the emitted light brightness at the center line in FIG. 10, and FIG.
The angular distribution of the emission light brightness at the position of mm is shown. It can be seen from these graphs that there is almost no light emitted in the normal direction.

According to the present invention, the emitted light is thus concentrated in a specific direction, the emitted light distribution is as small as possible, and the emitted light amount is large.
Utilizing 16 skillfully, emitted light on both sides of the normal 20,21
The above-mentioned object is achieved by the reflecting action of the outgoing light adjusting member and the diffusing action of the diffusing plate, which will be described later (see FIG. 8 (b)).

The shape of the lens 16 of the light guide is not particularly limited as long as the emitted light is concentrated in a specific direction, the emitted light distribution is as small as possible, and the emitted light amount is large.

Further, as the emitted light adjusting member of the present invention, a translucent sheet having a reflection pattern whose area is inversely proportional to the distance from the light source is preferable, and for example, the one disclosed in Japanese Utility Model Application No. 61-171001 can be used. it can.

[Examples] Hereinafter, a specific configuration of the surface light source element according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partially cutaway perspective view showing an embodiment of a surface light source element according to the present invention. FIG. 2 is a partial sectional view taken along the line I-I, showing a sectional view near the light source 14.

In FIGS. 1 and 2, 14 is a light source such as a fluorescent lamp, 15 is a reflector thereof, 13 is a reflecting surface formed on the side opposite to the exit surface of the light guide, 16 is the lens unit as described above, 50 Is a light guide having the lens unit 16, 51 is an outgoing light adjusting member, and 52 is
Is a light diffusion plate. The lens unit 16 has a linear projection shape extending in a direction parallel to the light source (lamp) 14.

The light source 14 is installed on at least one side edge 11 of the light guide,
The side end 11 is used as a light incident surface, and the surface on which the lens unit 16 is arranged is a light emitting surface. Further, the light guide body 50 is provided with the reflection layer 13 on the surface opposite to the emission surface, and not only the light directly incident on the emission surface but also the light reflected by the reflection layer 13 is emitted toward the emission surface. Let The light rays 60 and 61 shown in the figure are examples thereof, and are emitted at angles of i ₁ and i ₂ with respect to the surface of the diffusion plate, respectively.

The emitted light adjusting member 51 has a pattern of a reflective layer as described later, and a large amount of light in the portion close to the light source is reflected, and the central portion is almost transmitted. That is, the light emitted from each lens unit 16 is reflected or transmitted by the emitted light adjusting member 51 according to its position, and the light amount near the light source 15 and the light amount in the central portion are made uniform. This action is that the light is emitted in a state in which the light has directionality by the lens, and the reflection layer pattern provided on the emission light adjusting member and the reflection layer 13 of the light guide body are provided.
The surface reflection of the light guide body 50 or the like is repeated, and the effect is enhanced.

The diffusing plate 52 is an omnidirectional plate that is normally used for diffusing light.

In this embodiment, the emitted light adjusting member 5 is provided on the light guide body 50.
1 and the diffusion plate 52 are arranged in this order. The emission light adjusting member 51 and the diffusion plate 52 are arranged on the light guide body 50 only by placing them. An extremely thin air layer is formed between each of the adjusting member 51 and the light diffusion plate 52.

FIG. 3 is a plan view showing a configuration example of the emitted light adjusting member 51.

The emitted light adjusting member 51 has a film or sheet form, and the degree of reflection partially differs depending on the distance from the light source. The member 51 can be formed by partially attaching the reflective layer 51b to the transparent body 51a. That is, if a transparent body 51a, for example, a reflective layer, for example, an aluminum layer, is formed on the transparent body 51a, for example, a polyethylene terephthalate film, so that the area ratio of the reflective layer 51b gradually decreases from the edge on the light source arrangement side to the central portion. Good. FIG. 4 shows X- in FIG.
3 shows a graph of average reflectance R along X. As shown in FIG. 3, at the edge portion on the side where the hand-held light source is arranged, the size of each reflecting layer is large and the area of the transparent portion 51a is relatively small. Therefore, as shown in FIG. The average reflectance r at is relatively high. On the other hand, as shown in FIG. 3, the reflective layer 51 gradually extends from the edge portion on the light source arrangement side to the central portion.
Since the size of b decreases and the area of the transparent portion 51a gradually increases, as shown in FIG. 4, the average reflectance gradually decreases from the edge portion on the light source arrangement side to the central portion. Since the reflective layer 51b does not exist in the central region except the region within the distance x from the edge, the average reflectance is only the reflectance of the transparent body 51a itself.

As a material for forming the element of the present invention, an acrylic resin having the largest visible light transmittance as a light guide is suitable for the purpose of small size and light weight, but the material is not limited to this.

Although a small fluorescent lamp is used as the light source 14, a linear light source having a continuous shape (for example, a filament lamp) may be used.

Next, assuming a back light source for a liquid crystal display device having a size of 12 inches, a concrete example using a transparent acrylic resin with a panel size of 225 mm in width × 164 mm in length and a thickness of 5 mm for a light guide This will be described below. The following examples are merely examples, and it is obvious that the present invention is not limited to these in terms of size, thickness and material.

[Detailed Example 1] (Production of light guide) Pitch 0.38 mm, height of lens curved surface 0.051 mm (see FIG. 11)
Using the smooth curved multi-line lens mold,
A pattern was transferred to a 5 mm acrylic resin plate by heat pressing to prepare a light guide.

(Fabrication of outgoing light adjusting member) Metal image forming negative-positive type photosensitive material (KDP manufactured by Kimoto Co., Ltd., which is formed by laminating an aluminum thin film, a photosensitive layer, an adhesive layer and a cover film on a polyethylene terephthalate film having a thickness of 100 μm. )), And using the mask pattern to perform exposure and development according to the prescription of “KDP”,
A spot-shaped reflective layer 51 having a special pattern shown in FIG.
An output light adjusting member 51 having b was obtained. In the pattern of the reflection layer 51b of the emitted light adjusting member 51, the spot-like reflection layer portions are arranged in the vertical and horizontal directions with 30 pits / inch, and the reflectance r in FIG. 4 is 40%. Furthermore, x was set to 40 mm.

(Production of light diffusing plate) Milky white light diffusing plate (Acrylite ^# 43 manufactured by Mitsubishi Rayon Co., Ltd.)
2.2 mm thick) was cut into a size of 225 mm in width × 164 mm in length to obtain a light diffusion plate.

(Production of surface light source element) Next, two sides of 225 mm in width of the light guide body obtained above are polished by a conventional method, and two sides of 164 mm in length are attached with a polyester film with an aluminum vapor deposition film with an adhesive, A polyester film with a silver vapor deposition film was placed on the opposite side of the transferred lens surface. The emitted light adjusting member was placed on the surface of the light guide body so as to correspond to the shape, and the light diffusing plate was placed on the emitted light adjusting member. Then, a two-sided adhesive tape was attached to the two opposing end faces of the corresponding light guide, emission light adjusting member, and light diffusing plate to prepare a joined body composed of three members.

A lamp (FL-8D manufactured by Erebum Co., Ltd., diameter: 15.5 mm) was wrapped around an aluminum foil as a reflector along two sides of a width of 225 mm of the thus obtained joined body (this embodiment configuration example 1). ), And (CB7-300 manufactured by Stanley Electric Co., Ltd.
A surface light source element according to the present invention was obtained by making a light source (S, diameter 7.0 mm) wound with an aluminum foil as a reflector (Example 2 of the present embodiment) so that it could be turned on.

Also, in order to make a comparison by the thickness of the light guide,
The emission light adjusting member and the light diffusing plate used were the same as those in the first embodiment, and a light guide having a thickness of 8 mm was manufactured (third embodiment).

(Production of Comparative Configuration Examples 1, 2, and 3) For comparison, a conventional surface light source element was produced with the same configuration except that a light guide body in which a lens unit was not used was used. The light guide used in this comparative example was manufactured as follows.
Acrylic resin pellets (Mitsubishi PET, Hypet
HBS [registered trademark]) with 1.5% by weight of rutile titanium oxide
It was dry blended to form a 75μ thick film in a conventional extruder. The film was spread on an inorganic glass flat plate without air bubbles and temporarily fixed with methyl methacrylate, and then a cell was formed with a glass plate through a spacer by a usual method, and methyl methacrylate half-polymerization was performed in this clearance. Syrup was injected and polymerized and solidified in the usual manner to produce 5 mm and 8 mm thick resins integrally having a diffusion layer. Also in this case, in order to correspond to the above-mentioned embodiment, as a light source, (FL-8D manufactured by Matsushita Electric Industrial Co., Ltd.) is wrapped with aluminum foil as a reflector (Comparative configuration example 1), and (CB7-300S manufactured by Stanley Electric Co., Ltd.). An aluminum foil was wound as a reflector (Comparative configuration example 2). Further, a comparative structure example 3 having a thickness of the light guide of 8 mm was prepared corresponding to the structure example 3 of the embodiment.

(Measurement of Outgoing Light Distribution and Luminance) With respect to the central part of the panel (refer to FIG. 10 (a)) of the embodiment configuration example 1 and the comparative configuration example 1, a luminance meter (luminometer nt-1 manufactured by Minolta Co., Ltd.) Measurement was performed by changing the angle with respect to the line, and the emitted light distribution was obtained (see FIG. 10 (b)). The measurement result is shown in FIG. In addition, FIG. 6 shows the outgoing light distribution of Comparative Configuration Example 1.

Moreover, the measurement results of the peak luminance values of the respective Examples and Comparative Examples are as shown in Table 1 below.

{5} Comparative evaluation As can be seen by comparing FIG. 5 and FIG. 6, the comparative constitution example 1 has a characteristic that light is uniformly emitted in all directions, whereas The light source element can obtain a relatively concentrated light in the direction of -50 ° to 0 ° to 50 °, and
The peak luminance value at the center point is about 1.5 times that of the conventional comparative example regardless of the thickness of the light guide and the lamp diameter, which is an advantage that a high-luminance surface light source can be obtained.

Detailed Example 2 (Fabrication of Light Guide) As described above, the shape of the lens 16 of the light guide is such that the emitted light is concentrated in a specific direction, the emitted light distribution is as small as possible, and the emitted light amount is large. If so, it is not particularly limited. As an example of such a lens shape, the following light guides were prepared including the light guide of the convex cylindrical lenticular lens of the detailed example 1 described above.

(1) Substantially the same shape as the convex cylindrical lenticular lens shown in FIG. 11, composed of a pitch P = 0.38 mm, a height H = 0.05 mm, and a light guide thickness t = 6 mm.

(2) Trigonal prismatic lenticular lens A shape as shown in FIG. 12, which has a pitch P = 0.5 mm, a vertex angle θ = 25 °, and a light guide thickness t = 6 mm.

(3) Concave Lenticular Lens A shape as shown in FIG. 13, which is composed of cylindrical concave pitch P = 0.5 mm, depth D = 0.06 mm, and light guide thickness t = 6 mm. ..

(4) Polygonal pyramidal lenticular lens The shape is as shown in FIG. 14, and the pitch P ₁ = 0.10 mm, θ ₁ = 30 °, the pitch P ₂ = 0.15 mm, θ ₂ = 10 °, the pitch P ₃ = 0.15mm, θ ₃ = 5 °, height H = 0.097mm, overall pitch = 0.8mm, light guide thickness t = 6mm.

(5) have a shape as shown in anisotropic lenticular lens anisotropic lenticular lenses A FIG. 15 (a), the pitch P = 0.41 mm, the height H ₁ = 0.051 mm, the thickness t of the light guide = 6 mm.

Anisotropic lenticular lens B having a shape as shown in FIG. 15 (b), which has a pitch P = 0.41 mm, a height H ₂ = 0.102 mm, and a light guide thickness t = 6 mm. .

Each of these light guides was formed by transferring a pattern to an acrylic resin plate having a thickness of 6 mm by hot pressing using a mold having a predetermined shape.

(Emission Characteristics of Light Guide) The angular distribution of the emission light brightness of each light guide was obtained by the same method as that described in FIG. 10 (b). The structure in this case is called a surface type. When examining the angular distribution of the brightness of the emitted light, the lens 16 of the light guide 50 faces the reflecting surface 13 side, and after the light from the lens 16 is reflected by the reflecting surface 13,
A structure in which light is emitted from the emission surface 30 (hereinafter referred to as a back surface type)
In order to confirm whether the above can also be adopted, the above-mentioned light guide (1) ~
The lens surface of (5) was directed to the mirror, and the angular distribution of the emitted light brightness was measured. The state of the measurement is shown in FIG. 16 by taking the case of a triangular lenticular lens as an example.

Measurement result of angular distribution of outgoing light brightness The angular distribution of outgoing light brightness of the back surface type of the same shape as the cylindrical convex lenticular lens shown in Fig. 11 is shown.
It is shown in Fig. 17 (b). The surface type luminance distribution is
It is shown in Fig. 17 (a). The peak luminance was about 70 ° from the normal in the case of the back surface type and 70 to 80 ° from the normal in the case of the front surface type.

FIG. 18 (a) shows the angular distribution of the emission brightness of the surface type of the light guide of the triangular prismatic lenticular lens. In addition, the brightness distribution of the back surface type is shown in FIG. 18 (b). The peak luminance was 70 to 80 ° from the normal line for the front type and 30 to 35 ° from the normal line for the back type.

FIG. 19 (a) shows the angular distribution of the emission brightness of the surface type of the light guide of the cylindrical concave lenticular lens. Also, the luminance distribution of the back surface type is shown in FIG. 19 (b). The peak brightness was in the direction of 75 to 80 ° from the normal for both the front and back types.

FIG. 20 (a) shows the angular distribution of the luminance of the surface type output light of the light guide of the convex polygonal pyramidal lenticular lens. Also, the luminance distribution of the back surface type is shown in FIG. 20 (b). The peak brightness was in the direction of 75 to 80 ° from the normal for both the front and back types.

FIG. 21 (a) shows the angular distribution of the emission light brightness on the surface of the light guide of the anisotropic lenticular lens A. The luminance distribution of the anisotropic lenticular lens B is shown in FIG. 21 (b). The peak luminance was about 60 ° from the normal in the case of A and about 50 ° from the normal in the case of B.

(Production of surface light source element) Each of the light guides obtained as described above has a width of 225 mm.
The sides were polished by a conventional method, and a polyester film with a pressure-sensitive adhesive and an aluminum vapor-deposited film was attached to two sides with a length of 164 mm, and a polyester film with a silver vapor-deposited film was arranged on the opposite side of the transferred lens surface. On the surface of the light guide body, the emitted light adjusting member (the same as that used in the detailed embodiment 1) is placed corresponding to the shape, and the light diffusing plate is further placed on the emitted light adjusting member. (The same as that used in detailed Example 1) was placed, and the lens surface 16 of the light guide was provided on the side of the exit surface 30. Then, a two-sided adhesive tape was attached to the two opposing end faces of the corresponding light guide, emission light adjusting member, and light diffusing plate to prepare a joined body composed of three members. The width 22 of the joint thus obtained
Lamp (FL-8 made by Matsushita Electric Co., Ltd.)
A surface light source element (surface type) having the lens surface 16 of the light guide on the emitting surface 30 side was produced by winding aluminum foil as a reflector (D, diameter 15.5 mm).

On the other hand, for each light guide, a polyester film with a silver vapor deposition film is provided on the lens surface side, and the outgoing light adjusting member (the same as that used in detailed Example 1) is provided on the opposite side of the lens surface. ) Corresponding to the shape, and further, the light diffusing plate (the same as that used in the detailed example 1) is placed on the emitted light adjusting member, and the lens surface 16 serves as the emitting surface 30. A zygote with the configuration on the opposite side was created. Thereafter, a surface light source element (back surface type) having a structure in which the lens surface 16 is on the side opposite to the emission surface 30 was manufactured in the same manner as described above. As an example of these surface light source elements, front surface type and back surface type surface light source elements using a triangular column wrench are shown in FIGS. 22 (a) and 22 (b), respectively.

(Measurement of Luminance of Each Surface Light Source Element) As shown in FIG. 23, the panel of each surface light source element (as shown in FIG. 1) has 7 columns (A to G) × 11 columns (a to k). The lamp is lit by dividing the grid into equal parts, and the brightness in the normal direction is measured with a Minolta brightness meter nt-1 and the center of the grid is adjusted to about 10
Adjust so that the measurement points are on a circle with a diameter of
Points, measured. The results are shown in Table 2. In Table 2, the central one-column average is the column f in FIG.
The average brightness of the points is defined as the average of the front of the panel (77
Point) means the average light intensity.

As can be seen from Table 2, in the surface light source element including the light guide having the lens unit of each of the convex wrench, the triangular prism, the concave wrench, and the convex polygonal pyramid, the back surface type is slightly brighter than the front surface type. However, this difference is very small and can be sufficiently put to practical use.

(Distribution Light Distribution of Each Surface Light Source Element) With respect to each surface light source element, the distribution of the emission light at the central portion (intersection of column f, row D in FIG. 23) was measured according to the above-described measurement of the distribution of the emission light of the light guide. . The measurement result shows that the maximum brightness changes depending on each surface light source element and the distinction between the front surface type and the back surface type, but the emission light distribution itself is the same as the result (FIG. 5) of the embodiment of the present invention in the detailed embodiment 1. Almost no change, the surface light source element of the present invention is -50
It was possible to obtain light that was relatively concentrated in the direction of 0 ° to 50 °.

[Effects of the Invention] As described above, according to the surface light source element of the present invention, the following effects can be obtained.

It is possible to provide a light source device that is thin (similar to the diameter of a lamp) and has improved brightness without increasing the wattage of the light source and has good brightness uniformity over the entire surface as back lighting for various liquid crystal display devices and the like. . In particular, this is a great advantage in a liquid crystal display device in which portability and power saving are important.

Even when a fluorescent lamp that is essentially a diffuse light source is used, the brightness of the surface can be easily increased.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an embodiment of a surface light source element according to the present invention. FIG. 2 is a partial sectional view taken along the line I-I in FIG. FIG. 3 is a plan view showing a configuration example of the emitted light adjusting member. FIG. 4 is a diagram showing the reflectance distribution of the outgoing light adjusting member of FIG. FIG. 5 is a diagram showing the angular distribution of the emitted light luminance in the first structural example. FIG. 6 is a diagram showing the angular distribution of the emitted light luminance of Comparative Configuration Example 1. 7 (a) and 7 (b) are sectional views showing the structure of a conventional light guide. 8A and 8B are a perspective view and a sectional view showing a state in which the surface light source element according to the present embodiment is incorporated and the diffusion plate and the emitted light adjusting member are removed. 9 (a) and 9 (b) are diagrams showing the angular distribution of the emission light brightness of the light guide according to the present embodiment. FIG. 10 (a) is a front view of an apparatus incorporating this embodiment (
Is a measurement point), (b) is a sectional view taken along the line AA 'in FIG. FIG. 11 is a diagram showing an example of a lens unit of the light guide according to the present invention. FIG. 12 is a diagram showing a case where the lens unit of the light guide body is a triangular columnar lenticular lens. FIG. 13 is a diagram showing a case where the lens unit of the light guide body is a cylindrical concave lenticular lens. FIG. 14 is a diagram showing a case where the lens unit of the light guide is a convex polygonal pyramidal lenticular lens. FIGS. 15 (a) and 15 (b) are views showing the case where the lens unit of the light guide body is an anisotropic lenticular lens. FIG. 16 is a diagram showing a state in which the lens surface is directed to a mirror and the angular distribution of the emitted light brightness is measured. FIGS. 17 (a) and 17 (b) are views showing outgoing light distributions of the front surface type and the back surface type of the cylindrical convex lenticular lens, respectively. FIGS. 18 (a) and 18 (b) are diagrams showing outgoing light distributions of the front surface type and the rear surface type of the triangular columnar lenticular lens, respectively. FIGS. 19 (a) and 19 (b) are diagrams showing outgoing light distributions of the front surface type and the rear surface type of the cylindrical concave lenticular lens, respectively. FIGS. 20 (a) and 20 (b) are diagrams showing outgoing light distributions of a front surface type and a back surface type of a convex polygonal pyramid lenticular lens, respectively. FIGS. 21 (a) and 21 (b) are views showing outgoing light distributions of the anisotropic lenticular lenses A and B, respectively. FIGS. 22 (a) and 22 (b) are views showing a front surface type and a back surface type surface light source element using a triangular prism wrench, respectively. FIG. 23 is a diagram showing how to measure the luminance of the surface light source element. 16: Lens unit 13: Reflecting surface 14: Light source 15: Reflector 50: Light guide 51: Emission light adjusting member 52: Light diffusion plate 30: Light emission surface

Claims (1)

[Claims] 1. A light guide body having at least one side surface as an incident surface, a surface orthogonal to the side surface as a light emitting surface, and a reflection layer provided on a surface opposite to the light emitting surface; In a surface light source element including a diffusion plate that diffuses light omnidirectionally, a large number of lens units that emit light in a predetermined direction are arranged on the light emission surface of the light guide, and the lens units Respectively extend along the incident surface, and an output light adjusting member is arranged between the light guide and the diffuser plate, and the output light adjusting member moves away from the input surface. A surface light source element comprising a light reflection pattern whose area ratio gradually decreases.