JP2000250033A - Surface light source device - Google Patents

Abstract

(57) [Summary] In a radiation-coupled surface light source device, the luminance of a region having a large emission angle from a light source is increased. SOLUTION: An optical coupling portion 23 is provided at a part of an edge of a light guide plate 22.
And a light source 24 is provided so as to face the optical coupling unit 23.
The outer peripheral edge of the light guide plate 22 is a non-light emitting area 26 without the diffusion pattern 25. The first deflecting unit 30 is provided in the non-light-emitting area of the light guide plate 22 at a location where excess light is supplied. Light emitting area 27 provided with diffusion pattern 25
In the vicinity of the region R1 where the luminance is insufficient, the second deflection unit is provided in the non-light emitting region 26. The surplus light is deflected by the first deflecting unit 30 to be sent to the second deflecting unit 31, and is reflected by the second deflecting unit 31 to inject the light into the region R1 where the luminance is insufficient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a surface light source device. In particular, the present invention relates to a surface light source device using a light source smaller than a light guide plate.

[0002]

2. Description of the Related Art (Surface Light Source Device) The structure of a conventional surface light source device is shown in an exploded perspective view of FIG. This surface light source device 1
It comprises a light guide plate 3 for confining light introduced from the light incident surface 2, a light emitting unit 4, and a reflector 5. The light guide plate 3 is formed of a transparent resin having a large refractive index, such as polycarbonate resin or methacrylic resin. The diffusion pattern 7 is formed by printing or the like. The light emitting section 4 has a plurality of small light sources 9 such as light emitting diodes (LEDs) mounted on a circuit board 8, and faces the light incident surface 2 (side surface) of the light guide plate 3. The reflection plate 5 is formed of, for example, a white resin sheet having a high reflectance, and has both sides adhered to the back surface of the light guide plate 3 by a double-sided tape 10.

As shown in FIG. 2, light emitted from each light source 9 of the light emitting section 4 and incident on the inside of the light guide plate 3 from the light incident surface 2 is diffusely reflected when incident on the diffusion pattern 7.
Light reflected at an angle smaller than the critical angle of total reflection toward the light emitting surface 6 is emitted from the light emitting surface 6 to the outside. Further, light that has passed through a portion of the lower surface of the light guide plate 3 where the diffusion pattern 7 does not exist is reflected by the reflector 5 and returns to the inside of the light guide plate 3 again, so that loss of light amount from the lower surface of the light guide plate 3 is prevented.

However, in such a surface light source device 1, light emitted from the small light sources 9 arranged in a line is coupled to the light guide plate 3, and the light is planarized by the diffusion pattern 7 inside the light guide plate 3. Due to the widening, light controllability is not always good, and high efficiency and high uniformity are limited, and design is not easy.

(Radiation-Coupled Surface Light Source Device) Therefore, the applicant of the present invention has proposed a radiation-coupled surface light source device for coupling light of a small light source localized at one or one place to a light guide plate. are doing. FIGS. 3A and 3B show the configuration of the radiation-coupled surface light source device 11. A small light source 12 composed of an LED or the like is localized at one position on the end face of the light guide plate 13, and the light guide plate 13 is located at a position facing the light source 12 in FIG.
An optical coupling portion 14 having a shape as shown in FIG. Diffusion patterns 15 are arranged concentrically around the light source 12 on the back surface of the light guide plate 13. The diffusion pattern 15 has a uniform shape in the circumferential direction around the light source 12. As a result, the light from the light source 12 is deflected in a plane that is perpendicular to the light emitting surface and includes the direction connecting the light source 12 and the pattern, and also guides light that hit the diffusion pattern 15 and was not emitted from the light emitting surface. The light is guided linearly without changing the light direction. Further, a reflection sheet 16 is provided on the back surface of the light guide plate 13, and the light leaking from the back surface of the light guide plate 13 is reflected by the reflection sheet 16 to return to the inside of the light guide plate 13, thereby reducing light loss. Like that.

Thus, the light 18 emitted from the light source 12 and coupled to the optical coupling section 14 is guided into the light guide plate 13 while spreading radially. Light guide plate 1 from optical coupling section 14
The light 18 that has entered the light guide 3 travels while being totally reflected in the light guide plate 13 around the light source 12, and travels through the light exit surface 17 (the light guide plate 1).
3), the light is guided linearly. Light guide plate 13
The light 18 in the light enters the diffusion pattern 15 and the light exit surface 17
At an incident angle smaller than the critical angle of total reflection, the light is emitted from the light emitting surface 17 to the outside.

The amount of light emitted from the light exit surface 17 of the light guide plate 13 to the outside can be expressed by the product of the amount of light guided in the light guide plate 13 and the radiation loss coefficient, and the radiation loss coefficient compensates for the decrease in the amount of guided light. In this case, a uniform amount of emitted light can be obtained. The radiation loss coefficient is controlled by the density of the diffusion pattern 15. That is, in each direction,
The radiation loss coefficient is reduced by decreasing the pattern density of the diffusion pattern 15 near the light source 12, and the radiation loss coefficient is increased by increasing the pattern density as the distance from the light source 12 increases.
7, the brightness is made uniform.

As described above, the radiation-coupled surface light source device 11 is used.
In this case, since the light is linearly guided inside the light guide plate 13, it is necessary to control the directivity of the light source 12 according to the shape of the light guide plate 13, and the directivity is controlled by the shape of the optical coupling unit 14. are doing. FIG. 4 shows the ideal directivity of the light source 12 in the radiation-coupled surface light source device 11 using the rectangular light guide plate 13. In order to make the luminance in each direction on the light emitting surface uniform, the amount of light to be guided within a unit angle is almost proportional to the square of the distance from the light source 12 to the end of the light emitting plate 13 in each direction. I do. Therefore, the shape of the optical coupling portion 14 is made as shown in FIG. 3B, and the light is refracted by its lens action to form a diagonal direction (direction connecting the angle between the light source 12 and the light guide plate 13) ± θa. The light is collected to correct the light amount distribution.

[0009]

However, it is impossible to completely match the actual directivity with the ideal directivity.
Since luminance unevenness occurs depending on the directivity characteristics of the light source itself, the pattern density is reduced in the direction of higher light source luminance, and the luminance distribution is made uniform by adjusting to the pattern density in the direction of lower light source luminance. As a result, the corrected directivity is as shown by the solid line in FIG.

However, even if the optical coupling surface is designed in accordance with such corrected directivity, the directivity shown by the solid line in FIG. 5 is not actually obtained. The directivity is as shown by the broken line in FIG.
The deviation between the directivity indicated by the solid line and the actual directivity indicated by the broken line in FIG. 5 causes a variation in luminance in each direction. Has become. That is, in the surface light source device 11 having directivity as indicated by a broken line in FIG. 5, the light intensity is insufficient in the region R1 in the left and right corner directions and the region R2 in the diagonal direction as shown in FIG. Become. In the middle region R3 between the region R1 in the left and right corner directions and the region R2 in the diagonal direction, excess light that is not used is generated.

As a countermeasure against this, first, there is a case where the luminance is improved by increasing the density of the diffusion pattern 15 in a direction in which the luminance is insufficient. However, it is difficult to increase the density of the diffusion pattern 15 in a region R1 (a region where the emission angle from the light source 12 is large) in both right and left corner directions because the region is close to the light source 12. In order to eliminate or reduce the low-luminance region R1 in both corner directions, light having a large emission angle should not be used, and the distance between the light source 12 and the light-emitting region should be increased (that is, in both corner directions). No diffusion pattern is provided in a portion including the region R1), which is contrary to the demand for downsizing the surface light source device. In addition, if the overall luminance is reduced in accordance with the low luminance area, the luminance variation can be reduced. However, such a method goes against the demand for higher luminance of the surface light source device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned technical problems, and an object of the present invention is to provide a surface light source device capable of increasing the luminance of a region having a large emission angle from a light source. To provide.

[0013]

According to a first aspect of the present invention, there is provided a surface light source device comprising a light source smaller than a light guide plate, a light guide plate for confining light incident from the light source, and a diffuse reflection of light inside the light guide plate. An optical pattern that causes the light guide plate to emit light, and a first deflection that deflects the light that has reached the region of the light guide plate where the optical pattern is not provided toward another location in the region where the optical pattern is not provided. And a second deflecting unit for deflecting the light deflected by the first deflecting unit toward a region of the light guide plate where the optical pattern is provided.

According to a second aspect of the present invention, there is provided a surface light source device.
Wherein at least one of the first and second deflecting means in the surface light source device is a prism formed in an area of the light guide section where no optical pattern is provided.

According to a third aspect of the present invention, there is provided a surface light source device.
Wherein at least one of the first and second deflecting means in the surface light source device is formed of a curved surface.

According to a fourth aspect of the present invention, there is provided a surface light source device.
In the surface light source device described in the above, between the installation part of the first deflection means and the installation part of the second deflection means, an area provided with the optical pattern and an area not provided with the optical pattern The reflective member is provided so as to partition the light.

[0017]

In the surface light source device according to the first aspect of the present invention, the light reaching the region of the light guide plate where the optical pattern is not provided is deflected toward another place of the region where the optical pattern is not provided. And a second deflecting unit for deflecting the light deflected by the first deflecting unit toward an area of the light guide plate where the optical pattern is provided. If the first deflecting means is provided in the area where the surplus light quantity exists and the second deflecting means is provided near the area where the light quantity is insufficient, the surplus light quantity can be obtained by the second deflecting means by the first deflecting means. And the light can be guided from the second deflecting unit to a region where the amount of light is insufficient. Therefore, it is possible to balance the excess and deficiency of the amount of light and make the luminance distribution of the surface light source device uniform.

In the surface light source device according to the second aspect,
Since at least one of the first and second deflecting means in the surface light source device according to claim 1 is a prism formed in a region where the optical pattern of the light guide unit is not provided, Light incident on the first or second deflecting means can be reliably reflected and deflected by the prism. Therefore, the light amount loss in the first or second deflecting means can be reduced.

In the surface light source device according to the third aspect,
The first or second surface light source device according to claim 1.
Since at least one of the deflecting means is formed by a curved surface, when deflecting the direction of light by the deflecting means, the light can be sent while being converged by the condensing action of the curved surface. Therefore, while the light is deflected by the first and second deflecting means, the light can be prevented from gradually diverging, and the light can be efficiently transmitted from the surplus light amount region to the light shortage region.

In the surface light source device according to the fourth aspect,
2. The surface light source device according to claim 1, wherein the area provided with the optical pattern and the optical pattern are provided between the installation part of the first deflection unit and the installation part of the second deflection unit. 3. Since the reflection member is provided so as to partition the light from the non-existing area, the light deflected by the first deflecting means enters the area provided with the optical pattern on the way to the second deflecting means, thereby reducing the brightness unevenness. Never wake up.

[0021]

FIG. 7 is a plan view showing a surface light source device 21 according to one embodiment of the present invention. The surface light source device 21 is a radiation-coupled surface light source device. An optical coupling portion 23 is provided at the center of an edge of a light guide plate 22 formed of a transparent resin having a large refractive index such as polycarbonate resin or methacrylic resin. And the optical coupling unit 2
A small light source 24 made up of an LED or the like is arranged in 3. The optical coupling portion 23 has a shape substantially as shown in FIG. 3B, and is designed so as to obtain the directivity as shown by the solid line in FIG. The directivity is indicated by a broken line in FIG.

On the back surface of the region excluding the periphery of the light guide plate 22,
The diffusion patterns 25 are arranged concentrically around the light source 24. The diffusion pattern 25 has a uniform shape in the circumferential direction around the light source 24. Therefore,
The light guide plate 22 has a region around which the diffusion pattern 25 is not formed (hereinafter, referred to as a non-light-emitting region 26), and a region where the diffusion pattern 25 is formed (hereinafter, referred to as a light-emitting region 27). ing. The light from the light source 24 is deflected by the diffusion pattern 25 in a plane perpendicular to the light emitting surface 28 and including a direction connecting the light source 24 and the pattern. Therefore, the light that has not hit the diffusion pattern 25 and has not exited from the light exit surface 28 does not change its light guiding direction, and is guided linearly from the light source 24 in plan view. In each direction, the pattern density of the diffusion pattern 25 is reduced near the light source 24, and the pattern density is increased as the distance from the light source 24 increases, so that the brightness becomes uniform near and far from the light source 24. Like that. A regular reflection sheet 29 is provided on the back surface of the light guide plate 22 (FIG. 10), and light leaking from the back surface of the light guide plate 22 is reflected by the regular reflection sheet 29 so that the light guide plate 22 is formed.
It is returned inside to reduce light loss.

In the non-light-emitting area 26 located on the left and right side surfaces of the light guide plate 22, a first deflecting section 30 is provided on a side far from the light source 24, and a second deflecting section 30 is provided on a position near an end on the light source 24 side. Is provided. First deflecting unit 30
Are provided in a direction of ± α when viewed from the light source 24, and the direction ± α is included in a region R3 (see FIGS. 6 and 7) including excess light. The first deflecting unit 30 is configured as shown in FIG.
As shown in (a), the light guide plate 22 is formed in a prism shape so that the side surface thereof is cut out, and the light coming from a direction forming an angle of substantially α with the side surface of the light guide plate 22 is totally twice. By reflecting the light, the light is emitted in a direction substantially parallel to the side surface of the light guide plate 22.

As shown in FIG. 9B, the second deflecting portion 31 is provided near the low-luminance region R1 (see FIGS. 6 and 7) at both left and right corners. The side surface is formed so as to be cut out in a V-groove shape, and light coming from a direction substantially parallel to the side surface of the light guide plate 22 is totally reflected toward the region R1 (in particular, toward the light source 24). Like that.

Thus, in the surface light source device 21, the surplus light 32 included in the region R3 is supplied to the first deflecting unit 3
0, the first deflecting unit 30 as shown in FIG.
After being totally reflected twice, the light is changed in direction parallel to the side surface of the light guide plate 22 and enters the second deflecting unit 31. The light 32 incident on the second changing unit is totally reflected by the second deflecting unit 31, and is emitted toward the region R1. As a result, a part of the surplus light 32 emitted toward the region R3 is injected into the region R1 where the light amount is insufficient. As a result, it is possible to reduce the luminance variation without lowering the luminance of the entire light emitting region 27 of the surface light source device 21.

The light 3 reflected by the second deflecting unit 31
2 is reflected toward the light source 24,
Since the brightness of the other region is not changed by the light 32 injected into the region R1 from the opposite direction, the light can be supplemented only to the region R1.

Since there is a possibility that light enters the first deflecting unit 30 from a wide range to some extent, there is a possibility that the light will pass through the first deflecting unit 30 without being totally reflected by the first deflecting unit 30. is there. Therefore, light leakage is reduced by forming a prism shape. However, the light incident on the second deflecting unit 31 is limited only by the light deflected by the first deflecting unit 30, so that the light is deflected by one total reflection. Of course, the second deflecting unit 31 may be prismatic.

FIG. 10 is a rear view of the surface light source device 21.
Of the specular reflection sheet 29 attached to the back surface of the light guide plate 22, a portion facing the first deflecting portion 30 in the non-light emitting region 26, a portion facing the second deflecting portion 31, a first and a second portion. The portion between the deflecting units 31 is removed.

The specular reflection sheet 29 reduces light loss by reflecting light leaked from the back surface of the light guide plate 22 into the light guide plate 22. Since no light leaks from the back surface of the light guide plate 22 between the portions 31, the specular reflection sheet 2
9 is not required. Rather, the specular reflection sheet 2 is provided on the back surface of the light guide plate 22 between the first deflecting unit 30 and the second deflecting unit 31.
9, the light is absorbed or scattered by the specular reflection sheet 29, as shown in FIG. 11, and the efficiency is higher than the case where the light is guided only by total reflection (the case without the specular reflection sheet 29). descend.

Therefore, by removing the specular reflection sheet 29 between the first and second deflecting sections 31, the light 32 propagating from the first deflecting section 30 to the second deflecting section 31 is removed. Light 32 loss due to absorption and scattering is reduced, and light 3
(2) Improving usage efficiency.

(Second Embodiment) FIG. 12 shows a different structure of the first deflection section 30. In this embodiment, the first deflecting unit 30 that is obliquely inclined is formed by forming a V-groove at the edge of the light guide plate 22. First deflecting unit 3
The angle of 0 means that the light 32 coming from the light source 24
The light is set to be reflected in a direction parallel to the direction connecting 0 and the second deflecting unit 31. The first deflection section 30 is provided with a reflection member 33. The reflecting member 33 may be a mirror processing surface formed on the first deflecting unit 30 by depositing a metal film of aluminum, silver, or the like by vapor deposition or sputtering, or may be a member having a metal film adhered to the first deflecting unit 30. Good. Alternatively, a sheet having a high reflectance may be attached to the first deflecting unit 30 to form a reflecting member, or a paint having a high reflectance may be applied to the first deflecting unit 30 to form the reflecting member 33.

As described above, the reflecting member 3 is provided on the first deflecting section 30.
3, the first light is emitted at an angle that does not satisfy the condition of total reflection.
Even when the light enters the deflecting unit 30, the light is
Since the incident light beam can be surely reflected and deflected without leaking through 0, the degree of freedom in the shape design of the first deflecting unit 30 can be increased.

Although not shown, the second deflecting unit 31 may be mirror-processed similarly.

(Third Embodiment) FIG. 13 is a perspective view showing still another structure of the first deflection section 30. In the first deflecting unit 30, the first deflecting unit 30 has a prism shape in the thickness direction. By making the first deflecting unit 30 prism-shaped in the thickness direction as in this embodiment, the incident light 32 is totally reflected twice and
To the deflecting unit 31. Therefore, even with the first deflecting unit 30 having such a structure, light leakage can be reduced and light use efficiency can be improved.

Although not shown, the second deflecting unit 31
May also be prismatic in the thickness direction.

(Fourth Embodiment) FIG. 14 shows still another structure of the first deflecting unit 30. In this embodiment, a plurality of prism-shaped first deflection portions 30a, 30b,... In such a structure, for example, the first
The light 32 deflected by the deflecting unit 30a passes through the other first deflecting units 30b,... And is directed to the second deflecting unit 31.
The second deflecting unit 31 includes all the first deflecting units 30a and 3
0b,... Are sent to the second deflecting unit 3
The light is deflected by 1 and injected into the region R1. Therefore, according to such a configuration, it is possible to inject a larger amount of surplus light in the region R3 into the region R1 than in the case where there is one first deflecting unit.

The light 32 deflected by the first deflecting unit (for example, 30a) is turned into another first deflecting unit (for example, 30a).
b), the light 32 deflected by the first deflecting unit 30a or the like is vertically incident on other deflecting units 30b,... as shown in FIG. It is desirable.

(Fifth Embodiment) FIG. 15 is a partially broken plan view of a surface light source device 35 according to still another embodiment of the present invention. In this embodiment, the first deflecting unit 3
By forming the zero and second deflecting parts 31 with curved surfaces,
Each has a light condensing action.

The light traveling from the light source 24 to the first deflecting unit 30 is not parallel light, and the light source 24 actually has a certain spread. For this reason, if the light is reflected by the first deflecting unit 30 on a plane, there is a possibility that the light will diverge considerably before reaching the region R1.

On the other hand, in this embodiment, the light 32 deflected by the first deflecting unit 30 is sent to the second deflecting unit 31 while being condensed, and the light 32 is condensed by the second deflecting unit 31 while being condensed. Since it can be injected into R1, the divergence of the light 32 can be suppressed and the light can be efficiently guided.

(Sixth Embodiment) FIG. 16 is a partially broken plan view showing a surface light source device 36 according to another embodiment of the present invention. In this embodiment, the first deflecting unit 3 is configured to partition the light emitting region 27 and the non-light emitting region 26 near the boundary between the light emitting region 27 and the non-light emitting region 26.
0 along the region connecting the second deflecting unit 31 and the second deflecting unit 31.
7 are provided. In FIG. 16, a slit-shaped groove is formed in the light guide plate 22 as the reflection member 36 so that the light 32 is reflected by total reflection.

Ideally, all the light reflected by the first deflecting unit 30 goes straight to the second deflecting unit 31, but the light reflected by the first deflecting unit 30 is When the light enters the light emitting region 27 out of the way, unintentional emission occurs,
This may cause uneven brightness.

On the other hand, in this embodiment, since the reflecting member 37 is provided so as to partition the light emitting area 27 and the non-light emitting area 26, the light 32 reflected by the first deflecting unit 30 and traveling toward the light emitting area 27 is provided. Is reflected by the reflection member 37 and is prevented from entering the light emitting region 27, thereby suppressing the occurrence of uneven brightness.

When the reflection member 37 is provided by a slit-shaped groove formed in the light guide plate 22, if the groove is too long, the mechanical strength of the non-light emitting region 26 may be reduced at that portion. In order to prevent this, relatively short grooves may be arranged as shown in FIG. Alternatively, as shown in FIG. 17 (b), it may be prevented from penetrating a part or the entire length.

[0045]

According to the surface light source device of the first aspect,
If the first deflecting means is provided in the area where the surplus light quantity exists and the second deflecting means is provided near the area where the light quantity is insufficient, the surplus light quantity can be obtained by the second deflecting means by the first deflecting means. And the light can be guided from the second deflecting unit to a region where the amount of light is insufficient. Therefore, it is possible to balance the excess and deficiency of the amount of light and make the luminance distribution of the surface light source device uniform. Therefore, it is possible to reduce the variation in brightness of the surface light source device without hindering the size reduction of the surface light source device and without lowering the overall brightness.

According to the surface light source device of the second aspect, since at least one deflecting unit in the surface light source unit of the first aspect is a prism, the light incident on the first or second deflecting unit can be used. The light can be reliably reflected and deflected by the prism. Therefore, the light amount loss in the first or second deflecting means can be reduced.

According to the surface light source device of the third aspect, since at least one deflecting means in the surface light source device of the first aspect is formed by a curved surface, the direction of light is changed by the deflecting means. When the light is deflected, the light can be transmitted while being converged by the condensing action of the curved surface. Therefore, while the light is deflected by the first and second deflecting means, the light can be prevented from gradually diverging, and the light can be efficiently transmitted from the surplus light amount region to the light shortage region.

According to the surface light source device described in claim 4, in the surface light source device described in claim 1, between the installation portion of the first deflection means and the installation portion of the second deflection means, Since the reflecting member is provided so as to partition the area where the optical pattern is provided and the area where the optical pattern is not provided, the light deflected by the first deflecting means is transmitted to the second deflecting means. The light does not enter the area where the optical pattern is provided on the way, and does not cause uneven brightness.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a conventional surface light source device.

FIG. 2 is an operation explanatory view of the surface light source device of FIG. 1;

FIG. 3 is a perspective view showing a radiation-coupled surface light source device.

FIG. 4 is a plan view showing an optical coupling unit of the surface light source device of FIG.

FIG. 5 is a diagram showing ideal directivity of an optical coupling unit.

FIG. 6 is a diagram illustrating corrected directivity and actual directivity characteristics.

FIG. 7 is a plan view of a surface light source device according to an embodiment of the present invention.

FIG. 8 is a diagram illustrating the operation of a deflecting unit in the surface light source device of FIG. 7;

FIGS. 9A and 9B are enlarged views showing the behavior of light in a deflecting unit.

FIG. 10 is a rear view of a surface light source device according to another embodiment of the present invention.

FIG. 11 is a diagram for explaining the embodiment.

FIG. 12 is an enlarged plan view of a deflecting unit according to still another embodiment of the present invention.

FIG. 13 is an enlarged perspective view of a deflection unit according to still another embodiment of the present invention.

FIG. 14 is an enlarged plan view of a deflection unit according to still another embodiment of the present invention.

FIG. 15 is a partially broken plan view of a surface light source device according to still another embodiment of the present invention.

FIG. 16 is a partially broken plan view of a surface light source device according to still another embodiment of the present invention.

17A and 17B are schematic cross-sectional views of the reflection member in the embodiment of FIG.

[Explanation of symbols]

 Reference Signs List 22 light guide plate 23 optical coupling section 24 light source 25 diffusion pattern 26 non-light emitting area 27 light emitting area 30 first deflecting section 31 second deflecting section

Claims (4)

[Claims] A light source smaller than the light guide plate; a light guide plate for confining light incident from the light source; an optical pattern for diffusing and reflecting light inside the light guide plate to emit light from the light guide plate; First deflecting means for deflecting the light that has reached the area where the optical pattern is not provided toward another place in the area where the optical pattern is not provided, and light deflected by the first deflecting means. And a second deflecting unit for deflecting the light guide plate toward a region where the optical pattern is provided. 2. The surface according to claim 1, wherein at least one of the first and second deflecting means is a prism formed in a region where the optical pattern is not provided. Light source device. 3. The surface light source device according to claim 1, wherein at least one of the first and second deflecting means is formed by a curved surface. 4. An area where the optical pattern is provided and an area where the optical pattern is not provided are partitioned between an installation portion of the first deflection unit and an installation portion of the second deflection unit. The surface light source device according to claim 1, wherein a reflecting member is provided.