JP2002352616A - Surface light source device and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface light source device enhancing the efficiency of the light from a light source and providing bright illumination. SOLUTION: A light guide assembly 4 whose upper and lower surfaces are constituted almost parallel by stacking light guides 2, 3 having almost a wedge- shaped cross section. Fluorescent lamps 5A, 5B are arranged on facing sides 2b, 3b of the light guide assembly 4 respectively, and light beams from the fluorescent lamps 5A, 5B are guide with lamp reflectors 6A, 6B to the thicker side surfaces 2b, 3b of the light guides 2, 3 respectively. An embossed surface 13 for controlling the reflecting direction of light beams is formed on the lower surface 2c of the light guide 2, and an embossed surface part 14 for controlling the reflecting direction of light beams is formed on the inclined surface of the light guide 3. The end parts of the lamp reflectors 6A, 6B are fitted on the stacked surfaces of the light guides 2, 3 respectively. Thereby, light beams of the fluorescent lamps 5A, 5B are made incident only from the side surfaces 2b, 3b of the fluorescent lamps 5A, 5B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light source device used for a liquid crystal monitor of a liquid crystal television or a personal computer, and an image display device for illuminating an image display panel such as a liquid crystal display panel with the surface light source device. It is.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, a surface light source device used for such an image display device has fluorescent light sources as light sources on the side surfaces (incident surfaces) 22 and 23 of a flat light guide plate 21. Lamps 24 and 25 are arranged, and the fluorescent lamps 24 and 25
Light from the light guide plate 2 from the incident surfaces 22 and 23 of the light guide plate 21.
1, the light introduced into the light guide plate 21 is emitted from an upper surface (emission surface) 26 orthogonal to the incident surfaces 22 and 23 of the light guide plate 21, and the emitted light strikes the liquid crystal display panel 27 and the like. It is designed to be illuminated in a shape.

However, in the surface light source device as shown in FIG. 7, the light guide plate 21 has a rectangular cross section. Therefore, the light from the fluorescent lamps 24 and 25 that is incident on the incident surfaces 22 and 23 so as to be substantially orthogonal to the incident surfaces 2 and 23 of the light guide plate 21
The light was emitted to the outside from the side surface 23 (22) opposite to the side surface 2 (23), and the light was absorbed by the fluorescent lamp 25 (24) or the like and was not effectively used for illumination, and the light use efficiency was low. As a result, the surface light source device as shown in FIG. 7 was insufficient as a lighting device such as a liquid crystal monitor of a personal computer or a television which required a clear image display.

As an improvement over such a conventional surface light source device, a surface light source device as shown in FIG. 8 has been devised.
In the surface light source device shown in FIG. 8, the light guide plates 31 and 32 having a substantially wedge-shaped cross section are combined in such a manner that the slopes 31a and 32a are aligned with each other, and the side surfaces (incident surfaces) 31b and 32b are opposed to each other. Fluorescent lamps 33 and 34 as light sources are arranged, respectively, and the entrance surfaces 31 of the light guide plates 31 and 32 are arranged.
b, 32b are incident on the slope 31
a, 32a. In addition, the surface light source device shown in FIG.
c, a reflection means 35 for controlling the light reflection direction is formed, and a reflection means 36 for controlling the light reflection direction is formed on the inclined surface 32a of the upper light guide plate 32.
3 and 34 are effectively emitted from the emission surface 32c of the upper light guide plate 32 (for example, Japanese Utility Model Laid-Open No. 49-52059, Japanese Utility Model Laid-Open No. 3-12202, Japanese Patent Laid-Open No. 2000-2000). 268617).

[0005]

However, the surface light source device shown in FIG.
Light emitted to the outside from the side surfaces 31d and 32d opposite to the side surfaces 1b and 32b is not effectively used because the fluorescent lamps 33 and 34 absorb the light.
Is incident on the light guide plates 31, 32 from the side surfaces 31d, 32d opposite to the incident surfaces 31b, 32b of the light guide plates 31, 32, but the light guide plates 31, 3 from the side surfaces 31d, 32d.
It was found that the light incident on 2 was not effectively used for illumination.

That is, in the surface light source device shown in FIG. 8, of the light incident on the inside of the light guide plates 31, 32 from the side surfaces 31d, 32d opposite to the incident surfaces 31b, 32b of the light guide plates 31, 32, Light incident substantially orthogonally to the light guide plates 31d and 32d is reflected on the upper and lower surfaces (3
1a, 31c, 32c, 32a) and reflecting means 35, 36
Incident surface 31 of light guide plates 31, 32 without being reflected by
b and 32b are emitted to the outside and absorbed by a light source or the like. Therefore, the surface light source device shown in FIG.
The light from No. 34 could not be used effectively for illumination by the absorbed light.

Accordingly, the present invention provides a surface light source device capable of increasing the efficiency of using light from a light source and providing brighter illumination than the conventional example, and a surface light source capable of brighter illumination than the conventional example. It is an object to provide an image display device provided with the device.

[0008]

According to a first aspect of the present invention, a light guide plate having a substantially wedge-shaped cross section is overlapped to form a light guide plate assembly whose upper and lower surfaces are substantially parallel, and the light guide plate assembly is opposed to the light guide plate. The present invention relates to a surface light source device in which light sources are arranged on the side surfaces, and light emitted from these light sources is guided to the thick side surfaces of the light guide plate by reflection members. In this surface light source device, light reflection control means for controlling a light reflection direction is formed on one of the upper and lower surfaces of the light guide plate assembly, and light is reflected on at least one of the superposed surfaces of the light guide plate. A light reflection control means for controlling a reflection direction is formed, and an end of each of the reflection members is interposed on a superposed surface of the light guide plate.

According to this structure, the end of the reflection member interposed on the overlapping surface of the light guide plate blocks light from the light source from entering the thin side surface of the light guide plate. Therefore, the light of the light source is guided by the reflection member, and surely enters the inside of the light guide plate from the thick side surface of the light guide plate.

According to a second aspect of the present invention, in the surface light source device according to the first aspect of the present invention, the light guide plate assembly is constituted by a pair of light guide plates, and the light reflection control means is provided on an inclined surface of the light guide plates. Wherein the slope of one light guide plate is one of the upper and lower surfaces of the light guide plate assembly, and the slope of the other light guide plate is a surface overlapping with the one light guide plate.

With this configuration, the light guide plates to be superimposed can be shared, and it is not necessary to form another type of injection molding die according to the light guide plate.

According to a third aspect of the present invention, there is provided an image display device comprising: the surface light source device according to the first or second aspect; and an image display panel illuminated by planar illumination light emitted from the surface light source device. It is characterized by having.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a surface light source device 1 according to an embodiment of the present invention. 1 is an exploded perspective view of the surface light source device 1, and FIG. 2 is a cross-sectional view of the surface light source device 1 taken along line AA in FIG.

(Schematic Configuration of Surface Light Source Device and Image Display Device) As shown in these figures, the surface light source device 1 comprises two light guide plates 2 and 3 having a substantially wedge-shaped cross section, The light guide plate assembly 4 is formed by combining the light guide plates 2 and 3 such that the inclined surfaces 2a and 3a face each other, and the light guide plates 2 and 3 have thick side surfaces (incident surfaces) 2b and 3b. The fluorescent lamps 5A and 5B as light sources are arranged so as to face the light sources, and the light of the fluorescent lamps 5A and 5B is applied to the incident surfaces 2b and 3b of the light guide plates 2 and 3 facing each other with lamp reflectors (reflecting members) 6A and 6B. It is leading. In the surface light source device 1, the reflection sheet 7 is disposed so as to face the lower surface 2 c of the lower light guide plate 2, and the lower surface 2 of the lower light guide plate 2 is arranged.
The light emitted from c is reflected by the reflection sheet 7 and returned to the inside of the light guide plate 2. Also, this surface light source device 1
Is arranged such that two light control members 8 and 9 are overlapped so as to face the upper surface (emission surface) 3 c of the upper light guide plate 3.
The traveling direction of the light emitted from the emission surface 3c is controlled by light control members 8 and 9. In the surface light source device 1, the end portions 6A1 and 6B1 of the lamp reflectors 6A and 6B described above are interposed between the facing slopes (overlapping surfaces) 2a and 3a of the light guide plates 2 and 3, and the fluorescent lamp 5A , 5B to the light incident surfaces 2b of the light guide plates 2, 3,
The light from the fluorescent lamps 5A and 5B can be efficiently used as illumination light.

By disposing a liquid crystal display panel (image display panel) 11 above the light control members 8 and 9,
The surface light source device 1 constitutes a liquid crystal display device (image display device) 12 that illuminates the liquid crystal display panel 11 in a planar manner.

(Light guide plate and light guide plate assembly) Light guide plates 2 and 3
The light guide plates 2 and 3 have substantially the same external shape, and the light guide plates 2 and 3 are combined to form a light guide plate assembly 4. The upper and lower surfaces (3c and 2c) of the light guide plate assembly 4 are substantially parallel. The two light guide plates 2 and 3 are overlapped as described above. The light guide plates 2 and 3 are made of a resin material (polymethyl methacrylate (PMMA), polycarbonate (P
C), cycloolefin resin, etc.), and has a substantially wedge-shaped cross section.
That is, the light guide plates 2 and 3 are formed in a substantially right-angled triangular shape so that the cross-sectional shape becomes thinner as the distance from the fluorescent lamps 5A and 5B increases, and the emission surface shape corresponds to the liquid crystal display panel 11. It is formed in a substantially rectangular shape as shown in FIG.

The light guide plate assembly 4 includes a pair of light guide plates 2 and 3 arranged in opposite directions, and a combination of the light guide plates 2 and 3 such that their slopes 2a and 3a face each other. . On the lower surface 2c of the light guide plate 2 below the light guide plate assembly 4, a textured surface portion for diffusing light (light reflection control means)
13 is formed. As a result, the light guide plate 2 on the lower side of the light guide plate assembly 4 reflects the light propagating inside the light guide plate 2 by the slope 2 a and the embossed surface portion 13, and the light guide plate 3 on the upper side from the slope 2 a of the light guide plate 2. Emit light efficiently. The light guide plate 3 on the upper side of the light guide plate assembly 4 has a textured surface (light reflection control means) 14 formed on a slope (matching surface) 3a, which is a lower surface thereof, so that light propagating inside the light guide plate 3 is inclined 3a. In addition, the light is reflected by the textured surface portion 14 and transmits light emitted from the lower light guide plate 2 side, and efficiently emits light from the emission surface 3c which is the upper surface thereof.

(Fluorescent Lamp) The fluorescent lamps 5A and 5B
It is a rod-shaped body having a length corresponding to the width direction length of the incident surfaces 2b and 3b of the light guide plates 2 and 3, and the outer diameter thereof is
Are smaller than the plate thickness on the side of the incident surfaces 2b and 3b. The fluorescent lamp 5A is arranged at a predetermined interval so as to face the incident surface 2b of the lower light guide plate 2, and the fluorescent lamp 5B is arranged at the incident surface 3b of the upper light guide plate 3. Are arranged at predetermined intervals so as to oppose to each other. The light emitted from the fluorescent lamps 5A, 5B is reflected by the lamp reflectors 6A, 6B and enters the inside of the light guide plates 2, 3 from the incident surfaces 2b, 3b of the light guide plates 2, 3, or directly into the light guide plates. 2,3 incident surfaces 2b, 3
b enters the light guide plates 2 and 3.

(Lamp Reflector) The lamp reflectors 6A and 6B are open in the direction facing the incident surfaces 2b and 3b of the light guide plates 2 and 3, and the open end 6A1 and 6b.
6A2, 6B1, 6B2 are joined to the upper and lower sides of the light guide plates 2, 3, and the fluorescent lamps 5A, 5 are provided in a space formed by the inner surface and the incident surfaces 2b, 3b of the light guide plates 2, 3.
B is accommodated with a gap. The lamp reflectors 6A and 6B are formed of a resin material having excellent light reflectivity such as polyethylene terephthalate (PET), or formed by sheet metal processing of a thin metal such as a stainless steel plate.

The lamp reflector 6A assembled to the lower light guide plate 2 of the light guide plate assembly 4 has its lower end 6A2 sandwiching the end of the reflection sheet 7 arranged on the lower surface 2c of the light guide plate 2. The upper end 6A1 comes into close contact with the end of the inclined surface (overlapping surface) 2a which is the upper surface of the light guide plate 2. The lamp reflector 6B assembled to the upper light guide plate 3 has a lower end portion 6B1 whose light guide plate 3
Close to the end of the slope (overlapping surface) 3a which is the lower surface of
The light emitting surface 3c whose upper end 6B2 is the upper surface of the light guide plate 2
It comes to be close to. As a result, the side surface 3 on the tip end side (the opposite side to the incident surface 3b) of the upper light guide plate 3 having a small thickness
d is shielded from the lower fluorescent lamp 5A by the lower lamp reflector 6A, and the side surface 2d of the thin light guide plate 2 on the lower end side (the side opposite to the incident surface 2b) is positioned on the upper side. The lamp reflector 6B shields the upper fluorescent lamp 5B. Therefore, even if light is emitted to the outside from the side surfaces 2d and 3d on the distal end side where the thickness of the light guide plates 2 and 3 is thin, by providing an appropriate reflecting member, the light is re-incident on the light guide plates 2 and 3 and Not only can the use efficiency be improved, but also the fluorescent lamps 5A, 5B
Emitted from the light guide plates 2 and 3 are incident on the incident surfaces 2b and 3b.
The light is reliably guided by the lamp reflectors 6A and 6B, and enters the inside of the light guide plates 2 and 3 from the side surfaces 2d and 3d on the front end side (the opposite side to the incident surface) where the thickness of the light guide plates 2 and 3 is small. There is no such thing.

Here, it is assumed that the light of the fluorescent lamps 5A, 5B is applied to the side surfaces 2 of the light guide plates 2, 3 opposite to the incident surfaces 2b, 3b.
When the light enters the light guide plates 2 and 3 so as to be substantially orthogonal to the light guide plates 2 and 3, the light that has entered the inside of the light guide plates 2 and 3 is directly emitted to the outside from the incident surfaces 2 b and 3 b of the light guide plates 2 and 3 and the fluorescent lamps 5 A and 5 B
Etc. are absorbed. As a result, the light of the fluorescent lamps 5A and 5B is not effectively used for illumination, and the light use efficiency is reduced.

However, the surface light source device 1 according to the present embodiment
Can minimize the loss of the light emitted from the side surfaces 2d and 3d of the light guide plates 2 and 3, and can make the light re-enter the light guide plates 2 and 3 and reliably transmit the light of the fluorescent lamps 5A and 5B. Since the light can be guided to the two or three incident surfaces 2b and 3b, the light use efficiency is improved and the illumination luminance can be increased.

(Light Control Member) Two light control members 8 and 9 are arranged on the light exit surface 3c side of the light guide plate 3 in an overlapping manner. The light control members 8 and 9 are formed by applying a conventionally known means for light diffusion to a PET sheet, and are light diffusion sheets having a light diffusion function. That is, the light control members 8 and 9 can be made by mixing a light diffusing substance into PET,
A coating of a light diffusing substance is formed on the surface of the ET sheet, or the surface of the PET sheet is roughened (roughened), and when the light emitted from the light guide plate 3 passes, the light is diffused. I do. The two light control members 8 and 9 are connected to the light guide plate 3.
By disposing them on the light exit surface 3c side, the grained surface portions 13 and 14 formed on the light guide plates 2 and 3 become less visible from the light exit surface 3c side of the light guide plate 3 and the illumination quality is improved. Also,
The functions of the textured surface portions 13 and 14 formed on the light guide plates 2 and 3
Due to the synergistic effect of the functions of the light control members 8 and 9, the luminance peak of the emitted light is located on the normal direction side of the light emitting surface 3 c of the light guide plate 3, and the illumination luminance is increased.

(Reflection Sheet) The reflection sheet 7 is formed of a resin material having excellent light reflectivity (for example, white PET) in the form of a sheet, and has a shape corresponding to the lower surface 2c of the lower light guide plate 2. It has a rectangular shape and functions to reflect light emitted from the lower surface 2c of the lower light guide plate 2 and return it to the inside of the light guide plate 2.

(Function / Effect of Surface Light Source Device) As shown in FIG. 2, the light of the lower fluorescent lamp 5A is guided to the lamp reflector 6A and from the incident surface 2b of the lower light guide plate 2 to the inside of the light guide plate 2. After being incident on the light guide plate 2, the light propagates through the inside of the light guide plate 2, but is reflected by the embossed surface portion 13 of the lower surface 2c of the lower light guide plate 2 while propagating through the inside of the light guide plate 2, and is emitted from the slope 2a. Then, the light emitted from the slope 2 a of the lower light guide plate 2 enters the inside of the slope 3 a of the upper light guide plate 3, and propagates through the inside of the upper light guide plate 3, on the way of the slope 3 a of the upper light guide plate 3. The light is reflected by the textured surface portion 14 to be emitted from the emission surface 3c of the upper light guide plate 3, or emitted directly from the emission surface 3c of the upper light guide plate 3 to the outside. The light of the upper fluorescent lamp 5B is guided to the lamp reflector 6B, enters the light guide plate 3 from the incident surface 3b of the upper light guide plate 3, and then propagates inside the light guide plate 3. Is reflected by the embossed surface portion 14 of the inclined surface 3a of the upper light guide plate 3 during the propagation, and the light is emitted from the light exit surface 3c. Also, of the light of the upper fluorescent lamp 5B, the light emitted from the inclined surface 3a of the upper light guide plate 3 and then incident on the inside from the inclined surface 2a of the lower light guide plate 2 is the lower surface 2c of the lower light guide plate 2. The slope 2 of the lower light guide plate 2 is reflected by the textured surface portion 13.
a, and is returned to the inside of the upper light guide plate 3,
The light is emitted from the emission surface 3c of the upper light guide plate 3.

The light emitted from the light guide plate assembly 4 is diffused when passing through the two light control members 8 and 9,
The textured surface portions 13 and 14 of the light guide plates 2 and 3 are less likely to be visually recognized, and the luminance on the normal direction side of the emission surface 3c of the upper light guide plate 3 is maximized, so that the illumination luminance of the liquid crystal display panel 11 is increased.

FIGS. 4 and 5 show the emission light luminance distribution (visual characteristics) of the surface light source device 1 according to the present embodiment in comparison with the emission light luminance distribution of the conventional surface light source device. Among them, FIG. 4 shows, as shown in FIG. 3, the emission light luminance distribution in a direction (y direction) parallel to the fluorescent lamp 5A and substantially perpendicular to the center of the emission surface 3c of the light guide plate 3. (Visual characteristics). Further, FIG. 5 shows the emission light luminance distribution (visual direction) in a direction (x direction) perpendicular to the fluorescent lamp 5A and substantially perpendicular to the center of the light exit surface 3c of the light guide plate 3 as shown in FIG. Characteristic). 4 and 5, the measurement angle 0 ° indicates the normal direction (z direction) of FIG. 4 and 5, the emission light luminance distribution shown by the dotted line relates to the conventional surface light source device shown in FIG. 7, and the emission light luminance distribution shown by the solid line represents the surface light source device 1 of the present embodiment. It is about.

As shown in FIGS. 4 and 5, the surface light source device 1 of the present embodiment has the highest emission light luminance in the normal direction of the emission surface 3c of the light guide plate 3, and is shown in FIG. The emission light luminance is increased by about 7% to 11% as compared with the conventional example.

In this embodiment, the opening-side ends 6A1, 6A2, 6B1, of the lamp reflectors 6A, 6B are provided.
6B2 is bonded to the upper and lower sides of the light guide plates 2 and 3 so that the light of the fluorescent lamps 5A and 5B is only transmitted from the light incident surfaces 2b and 3b, which are the thicker sides of the light guide plates 2 and 3 inside the light guide plates 2 and 3. And the light from the fluorescent lamps 5A, 5B is prevented from being incident from the side surfaces 2d, 3d on the opposite side (thin wall side) of the light guide plates 2, 3 from the incident surfaces 2b, 3b. , 3 enter the fluorescent lamps 5A, 5B from the incident surfaces 2d, 3d of the light guide plates 2, 3, and a part of the light of the fluorescent lamps 5A, 5B emits fluorescent light. Lamp 5
B, 5A and the like can be prevented from being absorbed. As a result, in the surface light source device 1 of the present embodiment, the use efficiency of light of the fluorescent lamps 5A and 5B is improved as compared with the conventional surface light source device shown in FIG. The brightness of the illumination light increases. Further, the loss of light emitted from the side surfaces 2d and 3d is suppressed as much as possible, and an appropriate reflecting member is provided so that the light is incident again on the light guide plates 2 and 3.

(Modification of this Embodiment) FIG. 6 shows a modification of the above-described embodiment.
The same light guide plate 3 is used as the lower light guide plate. That is, the lower light guide plate 3 has a surface 3c orthogonal to the incident surface 3b as an overlapping surface, and the inclined surface 3a on which the grain surface portion 14 is formed.
Is arranged as a lower surface. If the light guide plate assembly 4 is configured in this manner, the light guide plate 3 in which the grain surface portion 14 is integrally formed on the inclined surface 3a during the injection molding can be commonly used on the lower side and the upper side. The cost can be reduced, and the product price of the surface light source device 1 can be reduced. In the surface light source device 1 according to the above-described embodiment, the lower light guide plate 2 has a textured surface portion 13 formed on a surface 2c orthogonal to the incident surface 2b, and the upper light guide plate 3 has a textured surface on the inclined surface 3a. Since the surface portion 14 is formed, it is necessary to separately prepare an injection mold for the upper light guide plate 3 and an injection mold for the lower light guide plate 2. However, according to this modification, the upper and lower light guide plates 3 and 3 can be injection-molded with one injection mold.

In the above-described embodiment, the coverage of the embossed surface portions 13 and 14 of the light guide plates 2 and 3 is
The coverage may be increased as the distance from A, 5B increases, or the coverage of the embossed surface portions 13, 14 may be changed between the light guide plates 2, 3. In addition, each light guide plate 2, 3 has a textured surface portion 13,
14 may be shifted.

Further, in the above-described embodiment, the aspect in which the embossed surface portions 13 and 14 are formed on the light guide plates 2 and 3 as the light reflection control means has been exemplified. May be formed by printing.

Further, in the above-described embodiment, an example has been described in which two light diffusion sheets are superposed and arranged as the light control members 8 and 9, but the present invention is not limited to this.
When a desired increase in luminance can be achieved by a synergistic effect with the light emitting device 4, at least one light diffusion sheet may be provided.

Further, a prism sheet or the like having a function of condensing light in a specific direction as the light control members 8 and 9 may be appropriately used instead of the light diffusion sheet, or a prism sheet or the like may be used together with the light diffusion sheet. It may be.

Further, light reflection control means may be formed on the inclined surface 2a of the light guide plate 2 or the light exit surface 3c of the light guide plate 3.

In the above-described embodiment, the configuration in which two light guide plates are stacked and combined is exemplified. However, the present invention is not limited to this, and the number of light guide plates to be combined may be appropriately changed according to the use of the surface light source device 1. Can be.

[0038]

As described above, the surface light source device of the present invention has
Since the end of the reflecting member is interposed between the upper and lower light guide plates so that the light of the fluorescent lamp enters the inside of the light guide plate only from the light incident surface on the thick side of the light guide plate, the fluorescent lamp The light can be efficiently used as the outgoing light, and the luminance of the illumination light can be improved.

Further, since the image display device of the present invention includes the surface light source device that emits bright illumination light as described above, the image on the image display panel is bright and easy to see.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a surface light source device showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the surface light source device taken along line AA of FIG.

FIG. 3 is a diagram showing a method of measuring the emission light luminance distribution of the surface light source device according to the embodiment of the present invention.

FIG. 4 is a diagram showing a comparison between the emission light luminance distribution of the surface light source device according to the embodiment of the present invention and the emission light luminance distribution of the conventional surface light source device, in a direction parallel to the fluorescent lamp and It is a figure which shows the emitted light luminance distribution on the surface orthogonal to the emission surface of a light guide plate.

FIG. 5 is a diagram showing a comparison between the emission light luminance distribution of the surface light source device according to the embodiment of the present invention and the emission light luminance distribution of the conventional surface light source device, in a direction orthogonal to the fluorescent lamp; It is a figure which shows the emitted light luminance distribution on the surface orthogonal to the emission surface of a light guide plate.

FIG. 6 is a cross-sectional view of a surface light source device according to a modification of the present invention.

FIG. 7 is a sectional view of a surface light source device according to a first conventional example.

FIG. 8 is a sectional view of a surface light source device according to a second conventional example.

[Explanation of symbols]

1 .... surface light source device, 2,3 ... light guide plate, 2b. 3b ...
Side surface (incident surface), 2c... Lower surface, 3a... Slope (overlapping surface), 3c.
A, 5B: fluorescent lamp (light source), 6A, 6B: lamp reflector (reflective member), 6A1, 6B1: end portion, 8, 9, light control member, 11: liquid crystal display panel (image display panel) ), 12: Liquid crystal display device (image display device), 13, 14: Textured surface portion (light reflection control means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) // F21Y 103: 00 F21Y 103: 00

Claims (3)

[Claims] 1. A light guide plate having a substantially wedge-shaped cross section is superimposed to form a light guide plate assembly whose upper and lower surfaces are substantially parallel, and light sources are arranged on opposite side surfaces of the light guide plate assembly. A light source for guiding the light emitted from the light guide plate to the thick side surface side of the light guide plate by a reflecting member, wherein the light is reflected on one of the upper and lower surfaces of the light guide plate assembly. Forming light reflection control means for controlling the direction, and forming light reflection control means for controlling the light reflection direction on at least one of the superposed surfaces of the light guide plate; A surface light source device, wherein the surface light source device is interposed on each of the superposed surfaces. 2. The light guide plate assembly comprises a pair of light guide plates, wherein the light reflection control means is formed on the slopes of the light guide plates, and the slope of one of the light guide plates is placed above the light guide plate assembly. 2. The light guide plate according to claim 1, wherein the lower surface is one of the lower surfaces, and a slope of the other light guide plate is a surface overlapping with the one light guide plate.
A surface light source device according to claim 1. 3. An image display device comprising: the surface light source device according to claim 1; and an image display panel illuminated by planar illumination light emitted from the surface light source device. .