JP2000294023A - Flat light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat light source device easily manufacturable of a simple structure capable of preventing generation of a bright line resulting from its reflector mounting structure while an enhanced front face brightness is realized using scattered light having high brightness and high directionality. SOLUTION: A light source 12 is arranged at least at a pair of confronting side ends of a photo-guide body 11, and a reflector 13 consisting of a reflector body 13 a and guide plates 13b is arranged so that the beam of light from the light source 12 is reflected and put incident to the inside from the side end 11b of the photo-guide body 11. The guide plates 13b are installed on the external wall surface in the neighborhood of the front extremities 13c and 13d of the reflector body 13a in such a way as partially protruding from the front extremities, wherein the front end face of the reflector body 13a is abutting to the side end face of the photo-guide body 11, and the projections on the guide plates 13b overlap the light emission surface 11a of the photo-guide body 11 and other surface 11c opposing to it so that the abutting part of the front extremities of the reflector body 13 with the side end of the photo-guide body 11 is covered from the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a surface light source device,
More particularly, the present invention relates to a technique for improving the performance of mainly preventing the generation of bright lines in a surface light source device suitably used as a backlight of a liquid crystal display device or the like.

[0002]

2. Description of the Related Art In recent years, a transmissive liquid crystal display (display) device has been frequently used as a display device of a word processor, a personal computer or the like. Such a liquid crystal display device is generally configured by arranging a planar illumination device, that is, a backlight, on the back surface of a liquid crystal element. This backlight has a mechanism for converting a linear light source such as a cold cathode discharge tube into planar light.

[0003] Specifically, a conventional backlight has a light source disposed directly below the back surface of a liquid crystal element, or a light source provided on a side surface thereof, and a surface light source is obtained using a light guide such as an acrylic plate. Is typical (side light method),
In particular, in the case of the latter sidelight method, an optical element such as a prism array is disposed on the light emitting surface of the light guide to obtain desired optical characteristics.

That is, a conventional side light type backlight (surface light source device) comprises a cold cathode discharge tube or the like at one end 1b of a light guide 1 made of an acrylic plate or the like as shown in FIG. A linear light source 2 is provided, and this is
The light guide 1 is provided with a diffusion plate 4 on the light exit surface 1a, and a light control sheet typified by a prism sheet 5 having a vertex angle of 90 degrees is provided thereon. Diffusion plate 6 on top
On the other hand, on the surface 1c opposite to the light exit surface 1a, a dot-like scattering / reflecting portion 7 made of white ink is formed by a printing technique, and foamed polyethylene terephthalate or diffuse reflection is formed in the vicinity of the surface 1c. Reflective sheet 8 made of material
The configuration constituted by disposing was typical.

[0005]

However, in this type of conventional sidelight type backlight, there is a problem that a bright line appears on the light emitting surface of the light guide. The generation of such bright lines lowers the commercial value of a surface light source device used for a liquid crystal backlight, an illuminator, and the like, and prevention thereof has been a major issue.

The cause of the generation of the bright line in this type of surface light source device will be briefly described as follows.
In the conventional surface light source device, as shown in FIG. 5, for example, a reflector 3 having a U-shaped cross section covers an open end 3a in the light emitting direction on an outer surface 1a near one end 1b of the light guide 1. It is wrapped and fixed with an adhesive 9.

Therefore, a part of the light emitted from the light source 2 adheres to the inner surface of the open end 3a, which is the overlapping portion of the reflector located on the light emitting surface 1a of the light guide 1 and the surface 1c facing the light emitting surface 1a. Since the light is incident and reflected via the agent layer 9 and the reflected light is incident on the light guide 1 again or directly from the light source vicinity area 1c 'of the surface 1c facing the light emitting surface 1a, the scattering reflection portion is provided. The light exits from the light exit surface 1a after being reflected by the reflection sheet 7 and the reflection sheet 8 or the like.

However, the conventional surface light source device configured as described above has a problem that the luminance value is low due to its structural characteristics including the use of a plurality of diffusion plates 4 and 6. In addition, recently, the performance required for such a backlight is becoming more and more advanced. In particular, in a portable personal computer or a TV monitor using a color liquid crystal display device, the extremely low light transmittance of the color liquid crystal cell itself necessitates a high luminance value required for a backlight light source. Absent.

For this reason, in the backlight of the sidelight type, it is inevitable to secure the front luminance by an optical condensing action by using a sheet composed of a prism array or the like frequently. However, although the use of a sheet made of a prism array or the like is effective for securing the front luminance, there is a problem in that the viewing angle characteristics are narrowed and the cost is greatly increased.

The most effective solution to such a problem is disclosed in Japanese Unexamined Patent Publication No. Hei 6-18879, which discloses a high-luminance directivity generated from a rough surface or light-scattering fine particles. This is an attempt to use highly scattered light.

However, when these directional scattered lights are used, the front luminance is relatively sufficiently ensured. However, when the bright line is generated by the above-described mechanism, a rough surface, light scattering fine particles, etc. As a result, since the light is reflected as scattered light having high directivity, there is a problem that the generation of bright lines becomes more serious than in the conventional surface light source device. For this reason, there has been a long-awaited need for a technique capable of providing a surface light source device that achieves both improvement in front luminance and prevention of generation of bright lines by simple means.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and a high luminance and high directivity scattered light generated from a rough surface, light-scattering fine particles, and the like is used. Another object of the present invention is to provide a surface light source device which has a simple structure and prevents production of a bright line due to a reflector mounting structure while improving the optical characteristics, and which is easy to produce.

[0013]

SUMMARY OF THE INVENTION The present invention is a surface light source device, and is configured as follows to solve the above-mentioned technical problem. That is, the surface light source device of the present invention includes a light guide having one surface serving as a light exit surface, and a light extraction mechanism formed on the other surface facing the one surface, and at least one pair of the light guides facing the light guide. A light source disposed on one or both of the side ends of the light source, and surrounding the outer periphery of the light source,
A reflector body opened in the direction of the light guide so as to reflect the light from the light source and enter the inside from the side end of the light guide, and an outer portion near a pair of front ends defining an open portion of the reflector body A reflector provided on a wall surface and having a guide plate protruding from the front end toward the light guide, and wherein the reflector abuts a front end surface of the reflector main body on a surface of a side end of the light guide, and includes a reflector main body. A part of the guide plate protruding from the front end of the light guide overlaps the light emitting surface of the light guide and the other surface facing the light guide so that the contact portion between the front end of the reflector body and the side end of the light guide is outside. It is characterized by being covered from.

<Specific Configuration of the Present Invention> The surface light source device of the present invention is composed of the above-mentioned essential components. However, the present invention is established even when the components are specifically as follows. The specific constituent element is characterized in that the reflector is attached to the light guide by bonding the front end face of the reflector body abutting on the surface of the side end of the light guide to the light guide. I do.

Further, in the surface light source device of the present invention, the reflector main body further includes a mounting bracket provided on a side portion thereof, and the reflector has a front end surface of the reflector main body attached to a surface of a side end portion of the light guide. It is characterized by being abutted and fixed to the light guide using a mounting bracket.

Further, the surface light source device of the present invention is characterized in that the light extraction mechanism is formed with a rough surface. In that case, it is preferable that the rough surface serving as the light extraction mechanism is formed in a large number of dots, and that each of the rough surface dots is basically separated from the light source, so that its area or arrangement density gradually increases. . In the surface light source device of the present invention, the light extraction mechanism is not particularly limited to a rough surface, for example, means for generating directional strong scattered light caused by inorganic fine particles or the like dispersed in a light guide, It is also preferable to use a means using printing with translucent ink in which inorganic fine particles and the like are dispersed.

Furthermore, the surface light source device of the present invention is characterized in that a light control sheet is disposed on the light exit surface of the light guide. This light control sheet preferably utilizes a downward prism array. Furthermore, in the surface light source device of the present invention,
By fixing the mounting bracket to a fixing surface formed on the light guide using a screw or an adhesive, the open end of the reflector can be pressed against the side end surface of the light guide to be fixed.

According to the surface light source device of the present invention configured as described above, a light beam entering the inside of the light guide from the light source installed at the side end of the light guide is defined as a light exit surface according to a conventional method. The light is reflected toward the light emitting surface by a light extraction mechanism provided on the opposite surface. In the surface light source device of the present invention, a pair of front ends (open ends) that define the open part of the reflector are arranged so as to abut on the side end surfaces of the light guide, so that the light emitted from the light source emits light. It is structurally impossible for the light to be reflected from the inner surface of the open end of the reflector and enter the interior of the light guide from the light exit surface or the surface facing the light guide.

As a result, no bright line is generated as in the conventional surface light source device, and therefore, a rough surface formed on the other surface of the light guide or inorganic light dispersed in the light guide is used as a light extraction mechanism. Even if scattered light with high directivity is generated by using means such as fine particles, a surface light source device having a simple structure, a high luminance value and no generation of a bright line without producing a bright line is obtained. Can be.

[0020]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a surface light source device according to the present invention. FIG. 1 shows a surface light source device 10 according to a first embodiment of the present invention. The surface light source device 10 according to this embodiment includes a light guide 11 having one surface 11a serving as a light emitting surface, and a light source 12 is provided at one of a pair of opposed side ends 11b.

As the light source 12, a fluorescent tube, an LED array or the like can be used, but it is not particularly limited to these light sources. As the light source 12 used in the surface light source device 10 of the present invention, it is most preferable to use a cold cathode tube having excellent light source luminance.

The surface light source device 10 of the embodiment shown in FIG.
As a typical example, is a so-called one-lamp type in which one cold-cathode tube is provided as a light source 12 only at one (light incident end) 11b of a pair of opposed side ends. . But,
In addition to such a configuration, a so-called two-lamp type, in which one cold-cathode tube is provided as a light source 12 at both of a pair of opposed side ends of the light guide 11, four sides of the light guide 11 A four-lamp type in which a cold cathode tube is provided as a light source 12 at all ends, or
It is also possible to use a lamp in which a cold cathode tube of a lamp is provided at one or both side end portions of the light guide 11 facing each other.

A reflector 13 is provided around each light source 12 so that the emitted light can be transmitted to the light guide 1 with as little waste as possible.
It is configured to be incident on one light incident end 11b. The reflector 13 includes a reflector main body 13a having at least one open side and a guide plate 13b. The reflector main body 13a defines a pair of open sections that emit light rays from the light source 12 and light reflected by the reflector 13. The front end (open end) is the light incident end 1 of the light guide 11
1b, it is arranged so as to be in contact with the light source 1b, thereby preventing a bright line which is likely to be generated near the light source.

The reflector main body 13a is not particularly limited as long as it can effectively reflect the light from the light source 12 disposed inside and make the light enter the light guide 11 through the opening. Instead, various shapes can be used.

The mounting structure of the reflector 13 will be described in more detail. The reflector main body 13a has the open end portions 13c and 13d whose end faces are connected to the light incident end portion 11 of the light guide 11.
b, and the outer surfaces of the open ends 1c and 13d are positioned so as to be substantially flush with the light exit surface 11a of the light guide 11 and the other surface 11c on the opposite side. It is bonded and fixed with interposition.

However, the thickness of the reflector body 13 is
Since it is about 0.2 mm, even if the end faces of the open ends 13c and 13d are bonded to the light incident end 11b of the light guide 11 with the adhesive 17, there is a concern that the fixing strength is slightly insufficient. In addition, since the thickness of the reflector body 13a is very thin as described above, the outer wall surfaces of the open ends 13c and 13d coincide with the light exit surface 11a of the light guide 11 and the other surface 11c on the opposite side. In other words, it is very difficult to accurately arrange the end face of the open end in contact with the light incident end 11b of the light guide 11 so as to form a continuous flat surface.

Therefore, the surface light source device 1 according to this embodiment
0, the tape-shaped guide plate 13b is
An open end 13 is provided on the outer wall surface near the pair of open ends 3a.
It is provided so as to protrude in the direction of the light guide 11 from c and 13d. The guide plate 13b is used for the reflector body 1
The guide plate 13b formed integrally with the reflector main body 3a may be formed integrally with the reflector body 1a with an adhesive or the like.
Alternatively, it may be attached and fixed to 3a. The tape-shaped guide plate 13b can be formed of relatively rigid paper or plastic, a thin metal plate, or the like.

When the reflector 13 having such a structure is attached to the light guide 11, the adhesive 17 is applied only to the end faces of the open ends 13c and 13d of the reflector main body 13a as described above. A pair of guide plates 13 is provided at the side end.
The two surfaces are relatively close to each other so as to fit between the light guide members b, and the end surface of the open end of the reflector main body 13a is brought into contact with the light incident end 11b of the light guide 11.

As a result, since the reflector body 13a is restricted from moving in the direction perpendicular to the light emitting surface 11a of the light guide 11 by the guide plate 13b, the end face of the open end and the light guide 11 Even if the reflector 13 is fixed to the light incident end 11b with the adhesive 17, the mounting strength of the reflector 13 can be made sufficient.

In addition, when the reflector 13 is mounted on the light guide 11, the open end 1
Since the positioning of 3c and 13d is only required to insert one side end 11b of the light guide 11 between the guide plates 13b,
It is very easy and a predetermined positioning accuracy can be reliably ensured.

Further, the light guide 11 is provided with various light extraction mechanisms. Particularly, in the surface light source device of the present invention, a rough surface or light scattering fine particles disclosed in Japanese Patent Application Laid-Open No. Hei 6-18879. It is most preferable that a scattered light having high intensity and excellent directivity, which is caused by the above, be used as a light extraction mechanism.

For example, a rough surface is provided as a light extraction mechanism,
When taking out the scattered light from the rough surface, graining of a gradation pattern or transfer of a dot pattern having a rough surface is effective. At this time, it is preferable to adjust the degree of the rough surface, the area occupied by the rough surface, and the like to make the luminance distribution uniform. Such uniform luminance on the light emitting surface is one of the characteristics required for the surface light source device.

In the surface light source device 10 shown in FIG.
The rough dots 14, 15, 16,... Provided on the surface 11c facing the light emitting surface 11a are typical examples thereof.
It is formed of a predetermined pattern, for example, a pattern arranged vertically and horizontally at a predetermined interval from each other. Not limited to such a dot pattern, a rough surface or a white ink application portion described later can be formed in an arbitrary pattern (shape). Forming the rough surface or the white ink-coated portion in an arbitrary pattern (shape) in this manner is generally called "patterning".

The rough dots 14, 15, 16,
Are configured so that the area of each dot increases as the distance from the light source 12 increases, so that the amount of light emitted on the light emitting surface 11a is as uniform as possible over the entire surface. In addition, from the viewpoint of uniforming the luminance distribution on the light emitting surface, that is, the light emitting surface 11a, the same applies to the case where the arrangement density of rough surface dots having the same area or different areas is increased as the distance from the light source increases. The effect can be obtained.

In this surface light source device 10, the rough surface dots 1
The light extraction mechanism constituting 4, 15, 16,... Includes a reflection sheet 18 disposed on the entire surface close to the surface on which the rough dots are formed. This reflection sheet 1
8 is preferably made of an ortho-emissive material such as silver.

The surface light source device 10 according to the present embodiment is composed of, for example, a triangular prism array having an apex angle of 60 to 70 degrees, and the apex portion is directed toward the light emitting surface 11a, and the light source 12 and the generatrix of each prism are parallel. The light control sheet 19 further includes a light control sheet 19, and the light control sheet 19 changes the direction of the emitted light and takes out the light.

According to the surface light source device 10 configured as described above, the light beam from the light source 12 incident from the one end 11b propagates in the light guide 11 according to the total reflection condition based on Snell's law. This light beam is applied to the rough dots 14, 1
When reaching the light extraction mechanism composed of 5, 16,..., A scattering phenomenon occurs, and the light rays are emitted without staying in the light guide 11 any longer.

At this time, there are a light beam directly emitted from the light guide 11 and a light beam emitted through reflection by the reflection sheet 18 provided on the surface 11c of the light guide 11 which is opposed to the light emission surface 11a. However, in any case, in the case of scattered light having high intensity and high directivity due to the rough surface dots 14, 15, 16,..., The direction of the emitted light greatly deviates from the normal direction of the light emission surface 11a, and is half value. The corner becomes narrow.

The light beam emitted in this manner is directed to a light control sheet comprising a triangular prism array in which the apex is directed toward the light emitting surface 11a and the light source 12 and the generatrix of each prism are arranged in parallel. By changing the angle at 19 and directing the luminance peak position to the normal direction of the light emitting surface 11a, illumination light with high luminance at the front can be obtained.

The surface light source device 1 according to this embodiment
At 0, since the reflector 13 is disposed such that the open ends 13c and 13d of the reflector main body 13a abut against the side end surfaces of the light guide 11, the light emitted from the light source 12 emits the light from the reflector main body 13a. End 13c, 1
It is structurally impossible that the light is reflected by the inner surface of the light guide 3d and enters the inside from the light emitting surface 11a of the light guide 11 or the surface 11c opposed thereto.

As a result, no bright line is generated as in the conventional surface light source device, and therefore, the rough dots 14, 15, 16, formed on the other surface 11c of the light guide 11 as a light extraction mechanism. Even if scattered light having high directivity is generated by using means such as inorganic fine particles dispersed in a light guide or the like, the bright line is not distinguished by this, the structure is simple, the luminance value is high, and the bright line is obtained. Can be obtained.

Next, a second embodiment of the surface light source device of the present invention will be described. In the surface light source device 20 of this embodiment, as shown in FIG.
A double-sided adhesive tape 21 is attached so as to wrap each of the open ends 13c and 13d.
1 and a guide plate 13b is attached to the outer wall surface of each open end. Here, the guide plate 13
b may be provided so as to cover the reflector main body 13a.

The surface light source device 20 according to the second embodiment is substantially the same as the surface light source device according to the first embodiment shown in FIG. 1 except for the configuration described above. Or, the corresponding components are denoted by the same reference numerals in FIG. 2 and the description thereof will be omitted.

As described above, when the double-sided adhesive tape 21 is attached to the respective open ends 13c and 13d of the reflector main body 13a, and the guide plate 13b is attached to the outer wall surface of each open end using the double-sided adhesive tape 21, The workability at the time of assembly can be improved as compared with the surface light source device 10 of the first embodiment shown in FIG.

In order to secure the mounting strength of the reflector body 13a, if it is unavoidable, the guide plate 13
An adhesive may also be provided on the overlap portion 22 between the light guide 11 and the light guide 11 to improve the mounting strength of the reflector.

FIGS. 3 and 4 show a third embodiment of the surface light source device of the present invention. In the surface light source device 30 of this embodiment, mounting brackets 13e are formed on both side ends of the reflector main body 13a. When the mounting bracket 13 e is arranged with the surfaces of the open ends 13 b and 13 c of the reflector main body 13 a abutting on the surface of the light input end 11 b of the light guide 11, the mounting bracket 13 e projects from both sides of the light guide 11. It is configured to be in close contact with the front end face of the portion 11d.

When the reflector 13 is mounted on the light guide 11, the mounting bracket 13 e of the reflector main body 13 a which is in close contact with the front end face of the mounting portion 11 d of the light guide 11 is fixed to the mounting portion 11 d by a set screw 31. Thereby, the reflector main body 13a has its open end 13c,
An acting force is applied to the light incident end 11b of the light guide 11 at all times.

Therefore, it can be expected that the fixing strength of the reflector 13 to the light guide 11 and the adhesion of the open end surface of the reflector main body 13a to the light entrance end surface of the reflector body 13a are improved. Structures other than these are the same as those of the surface light source device 10 of the first embodiment shown in FIG. 1, and the same or corresponding components are denoted by the same reference numerals in FIGS. Is omitted.

When the reflector main body 13a is fixed to the light guide 11 by the mounting bracket 13e, the open end 13c, like the surface light source device 10 according to the first embodiment, is used.
The adhesive 17 may be attached to the end face of 13d, or may be attached so as to surround the open ends 13c and 13d with the double-sided adhesive tape 21 as in the surface light source device 20 according to the second embodiment. .

Further, in the third embodiment described above, the mounting bracket 13e is fixed to the front end face of the mounting portion 11d of the light guide 11 with the set screw 31. May be fixed with an adhesive.

Regarding the light control sheet 19 disposed on the light exit surface 11a of the light guide 11, in addition to the prism having a triangular cross section, a prism having a polygonal cross section, a prism having a top curved surface, a cylindrical lenticular lens, A light control sheet formed of a group of pyramids having a polygonal cross section, a microlens array, a diffractive optical element array, or the like and having a shape designed to satisfy the above-described functions can also be suitably used.

In a preferred embodiment of the surface light source device of the present invention, each of the light guide 11 and the light control sheet 19 is formed of a resin material. In particular, an acrylic resin, a polycarbonate resin, a polyester resin, or a cyclic polyolefin resin is suitably used, and a group of optical elements formed on the surface of the light control sheet 19 is a known thermosetting represented by an acrylic resin or the like. What is formed with a property or a photocurable resin is preferable.

The light source as the light supply means in the surface light source device of the present invention is not particularly limited, but includes a fluorescent tube (cold cathode tube, hot cathode tube), a tungsten incandescent bulb, an optical rod, an LED array and the like. Representative. In particular,
It is most preferable to use a cold cathode tube as a linear light source that can be easily reduced in size and increased in luminance.

[0054]

As described above, according to the surface light source device of the present invention, while utilizing high-intensity highly directional scattered light generated from a rough surface or light scattering fine particles, etc. It is possible to provide a surface light source device which has a simple structure and is easy to produce, in which the generation of bright lines emitted from the light exit surface is prevented. These features respond to the demand for optical characteristics of illumination light for backlights of liquid crystal display devices, which have recently become more sophisticated.

[Brief description of the drawings]

FIG. 1 is a fragmentary sectional view schematically showing a surface light source device according to a first embodiment of the present invention.

FIG. 2 is a fragmentary sectional view schematically showing a surface light source device according to a second embodiment of the present invention.

FIG. 3 is a fragmentary sectional view schematically showing a surface light source device according to a third embodiment of the present invention.

FIG. 4 is a partial cross-sectional view showing the surface light source device shown in FIG. 3 along a line 4-4.

FIG. 5 is a cross-sectional view schematically showing a conventional representative surface light source device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Surface light source device 11 Light guide 11a Light emission surface of light guide 11b One end (light entrance end) of light guide 11c Surface opposite to light emission surface of light guide 12 Light source 13 Reflector 13a Reflector Main body 13b Guide plate 13c Open end 13d Open end 13e Bracket 14 Rough surface dot (light extraction mechanism) 15 Rough surface dot (light extraction mechanism) 16 Rough surface dot (light extraction mechanism) 17 Adhesive 18 Reflection sheet 19 Light control Sheet 20 Surface light source device 21 Double-sided adhesive tape 30 Surface light source device 31 Set screw

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H038 AA52 AA55 BA06 2H091 FA14Z FA21Z FA23Z FA32Z FA42Z FA45Z FB02 FB08 FC17 FC19 FC25 FD06 LA03 LA18 5G435 AA02 AA03 BB12 BB15 DD09 EE27 FF00 FF02 GG03 FF03 GG03 FF03 GG02 FF03 GG03 FF03 GG02

Claims (7)

[Claims] 1. A light guide having one surface serving as a light exit surface and having a light extraction mechanism formed on the other surface facing the one surface, and a light guide having at least a pair of side ends facing the light guide. A light source disposed on one or both of the light guides, the light guide surrounding the outer periphery of the light source, and reflecting light from the light source to be incident on the light guide from the side end of the light guide; And a reflector provided on an outer wall near a pair of front ends defining an open portion of the reflector main body, and a guide plate protruding from the front end toward the light guide. The reflector has a front end surface of the reflector main body abutting on a surface of the side end portion of the light guide, and a part of the guide plate protruding from the front end of the reflector main body is a part of the light guide. The light emitting surface and the The surface light source device, wherein the covering from the outside the contact portion between the end portion of the overlapped to each of the other surface to counter the front end and the light guide body of the reflector body. 2. The method according to claim 1, wherein the reflector is attached to the light guide by bonding a front end surface of the reflector main body, which is in contact with a surface of the side end portion of the light guide, to the light guide. The surface light source device according to claim 1, wherein: 3. The reflector body further includes a mounting bracket provided on a side portion of the reflector body, the reflector bringing a front end surface of the reflector body into contact with a surface of the side end portion of the light guide. The surface light source device according to claim 1, wherein the surface light source device is fixed to the light guide using the mounting bracket. 4. The surface light source device according to claim 1, wherein the light extraction mechanism is formed with a rough surface. 5. The light extraction mechanism according to claim 1, wherein the light extraction mechanism is configured to generate scattered light having high directivity caused by inorganic fine particles or the like dispersed in the light guide. The surface light source device according to any one of the above. 6. The light source device according to claim 1, wherein the surface light source device further includes a light control sheet provided on the light exit surface of the light guide. Surface light source device. 7. The surface light source device according to claim 2, wherein the mounting bracket is fixed to a fixing surface formed on the light guide by a screw.