JP3384483B2 - Sidelight type surface light source device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sidelight type surface light source device, and is applied to a sidelight type surface light source device using a point light source such as a light emitting diode as a primary light source. According to the present invention, uneven brightness in the vicinity of the incident surface is reduced by forming a plurality of grooves extending from the emission surface to the back surface at least in the region of the plate-like member facing the point light source.

[0002]

2. Description of the Related Art Conventionally, for example, in a liquid crystal display device,
A side light type surface light source device illuminates a liquid crystal display panel, thereby reducing the overall shape.

That is, in the side light type surface light source device, a primary light source is arranged laterally of a plate-like member (that is, a light guide plate), and illumination light emitted from this primary light source is guided from the end face of the light guide plate to the light guide plate. Incident. Further, the side light type surface light source device bends this illumination light and emits it toward the liquid crystal display panel from the plane of the light guide plate, whereby the overall shape can be made thin.

Such a side light type surface light source device is
There are a system in which the primary light source is configured by a rod-shaped light source such as a fluorescent lamp, and a system in which the primary light source is configured by a point light source such as a light emitting diode. The latter can simplify the drive circuit of the primary light source. There are features such as.

FIG. 10 is an exploded perspective view showing an example of this latter sidelight type surface light source device 1, and FIG. 11 is a sectional view showing FIG. 10 taken along the line AA. The side light type surface light source device 1 is formed by arranging a primary light source 3 on a side of a light guide plate 2 and sequentially laminating a reflection sheet 4, a light guide plate 2 and a wavelength conversion sheet 6.

The primary light source 3 is formed by mounting a plurality of light emitting diodes 7 which are point light sources on a holding member 8 such as a printed circuit board, and the illumination light emitted from these light emitting diodes 7 is applied to an end face of the light guide plate 2 (hereinafter referred to as an end face). It is incident on 2A. Here, as the light emitting diode 7 of this type, for example, a blue light emitting diode that emits blue illumination light, which is sealed in a rectangular resin package, is applied.

The light guide plate 2 is formed in a flat plate shape by injection-molding acrylic (PMMA resin) made of a transparent member, and the illumination light of the primary light source 3 is incident from the incident surface 2A. As a result, the light guide plate 2 repeatedly reflects between the reflection sheet 4 side plane (hereinafter referred to as the back surface) 2B and the wavelength conversion sheet 6 side plane (hereinafter referred to as the emission surface) 2C, and propagates the illumination light. At the time of reflection on 2B and emission surface 2C, a component having a critical angle or less is emitted from back surface 2B and emission surface 2C.

Further, the light guide plate 2 has a light scattering surface 2D formed on the back surface 2B. Here, this light scattering surface 2D is shown in FIG.
As shown in FIG. 2, the back surface 2B is formed by partially forming an embossed surface so that the degree of light scattering gradually increases from the incident surface 2A side toward the other end. The light-scattering surface 2D may be formed by selectively adhering a light-scattering ink made of, for example, magnesium carbonate or titanium oxide as a pigment instead of the textured surface. More specifically, the light scattering surface 2D forms a satin area in a rectangular shape, for example, at a constant pitch or in a random arrangement, and the area of each rectangular area is sequentially increased from the incident surface 2A side toward the other end. Are formed to increase. Thereby, the light guide plate 2 has the back surface 2B and the exit surface 2C.
The illumination light that is repeatedly reflected and propagated between and is scattered by the light-scattering surface 2D to increase the component having a critical angle or less with respect to the emission surface 2C. In the sidelight type surface light source device 1, the illumination light is thereby emitted from the emission surface 2C.

The reflection sheet 4 is formed of a sheet-like regular reflection member such as a metal foil or a sheet-like irregular reflection member such as a white PET film, and reflects the illumination light leaking from the back surface 2B to reflect the light guide plate 2. To improve the utilization efficiency of illumination light.

The wavelength conversion sheet 6 is made of a sheet material containing a fluorescent material. When the fluorescent material is excited by blue illumination light to emit light, the blue illumination light is corrected into white illumination light and emitted. . At this time, the wavelength conversion sheet 6 diffuses and emits the white illumination light. As a result, in the sidelight type surface light source device 1, the point light source by the blue light emitting diode 7 is used as the primary light source, and the white illumination light is emitted from the emission surface 2C.

[0011]

By the way, such a sidelight type surface light source device 1 has a drawback that the amount of emitted light decreases as the distance from the light emitting diode 7 increases along the incident surface. As a result, in the sidelight type surface light source device 1, there is a problem that a region B having a low brightness level is formed near the incident surface 2A, between the light emitting diodes 7, etc., and uneven brightness occurs near the incident surface. By the way, in the conventional side light type surface light source device 1, by using only the region on the front end side excluding these regions B, this uneven brightness is avoided and high-quality illumination light is emitted. .

If the amount of light emitted from these areas B can be increased to the same extent as that of the other areas, the light emitting surface of the light guide plate 2 can be effectively used, and the side light type surface light source device can be miniaturized accordingly. can do.

The present invention has been made in consideration of the above points, and an object thereof is to propose a side light type surface light source device capable of reducing uneven brightness in the vicinity of the incident surface.

[0014]

In order to solve such a problem, in the invention of claim 1, the illumination light emitted from the point light source is incident from the end face of the plate member, and the illumination light is bent to bend the plate member. The present invention is applied to a side light type surface light source device that emits light from the light emitting surface. The plate-like member, the region facing the point light source of at least the end face, have a plurality of grooves extending on the emission surface which faces from the output surface, this groove, obliquely to the end face
A pair of slanted planes that are inclined planes or curved surfaces
It should be formed by connecting smoothly .

[0015]

According to the invention of claim 2, claim 1
In the above configuration, the plurality of grooves are formed so that the depth gradually decreases as the distance from the center of the point light source increases.

According to the invention of claim 3, claim 1
Alternatively, in the configuration of claim 2, when viewed from the emission surface side, all or part of the region facing the point light source is concave,
A plate member is formed.

According to the structure of claim 1, in the side light type surface light source device in which the illumination light emitted from the point light source is incident from the end face of the plate member, the illumination light is bent and emitted from the emission surface of the plate member. By forming a plurality of grooves extending from the emitting surface to the surface facing the emitting surface at least in the region of the end surface facing the point light source, the illumination light emitted from the point light source is formed in the surface along the emitting surface. Can be distributed to both side surfaces and guided to the inside of the plate-shaped member. In addition, the illumination light can be prevented from spreading in the in-plane direction perpendicular to the incident surface. As a result, on the exit surface along the entrance surface,
It is possible to effectively avoid the increase of the brightness level in the vicinity of the point light source, and increase the brightness level of the area distant from the point light source. Specifically, a flat surface that is inclined with respect to the end face
Smoothly connect a pair of slopes made of surfaces or curved surfaces with curved surfaces
If this groove is continuously formed, the illumination light will be reflected on both sides by the slope.
When distributing to the side, a sudden change in this distribution amount
It can be effectively avoided and the brightness of the slope connection
The occurrence of la can be effectively avoided.

[0019]

According to the second aspect of the present invention, if the plurality of grooves are formed so that the depth is gradually reduced as the distance from the center of the point light source is increased , when the light is distributed to both side surfaces, reflection by other grooves or the like is caused. It can be reduced and can be efficiently distributed to the side surface.

According to the third aspect of the invention , if the plate-like member is formed so that all or part of the region facing the point light source is concave when viewed from the emission surface side, the concave portion can also be used. The illumination light can be spread in a plane parallel to the emission surface, and the illumination light can be efficiently distributed to both sides.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings as appropriate.

(1) First Embodiment FIG. 1 is a perspective view showing a light guide plate 12 applied to a sidelight type surface light source device according to a first embodiment of the present invention together with a primary light source 3. . In this sidelight type surface light source device, the reflection sheet 4 is laminated on the back surface 12B of the light guide plate 12 and the wavelength conversion sheet 6 is laminated on the emission surface 12C.
In the sidelight type surface light source device according to this embodiment, the same components as those of the sidelight type surface light source device 1 described above with reference to FIG. 10 are denoted by the corresponding reference numerals, and the duplicate description will be omitted.

The light guide plate 12 is formed in a flat plate shape by injection-molding a transparent member such as acrylic (PMMA resin), and the illumination light of the primary light source 3 is incident from the incident surface 12A. As a result, the light guide plate 12 has the back surface 12B and the exit surface 12
The illumination light propagates by being repeatedly reflected between C and C, and when reflected on the back surface 12B and the emission surface 12C, a component having a critical angle or less is emitted from the back surface 12B and the emission surface 12C.

Further, in this light guide plate 12, a light scattering surface similar to the conventional one is formed on the back surface 12B, whereby the back surface 12B.
The illumination light that is repeatedly reflected and propagated between the light emitting surface 12C and the emission surface 12C is scattered by the light scattering surface, and the illumination light can be emitted from the emission surface 12C with a desired distribution.

The light guide plate 1 for emitting the illumination light in this manner
2 is an incident surface 12A, as shown enlarged by an arrow C.
The grooves 13 having the same shape are repeatedly formed. Here, these grooves 13 are formed so as to extend from the emission surface 12C to the back surface 12B and are repeatedly formed on the entire surface of the incidence surface 12A. In FIGS. 1 and 2, the groove 13 is shown in an enlarged manner for clarity.

Further, as shown in FIG. 2, this groove 13 is
A pair of inclined surfaces 13A and 13B, which are inclined planes with respect to the incident surface 12A, are smoothly connected by an arcuate curved surface 13C, and a similar arcuate curved surface 1 is formed.
It is designed to be smoothly connected to the adjacent groove by 4.

In the above structure, the illumination light emitted from the light emitting diode 7 (FIG. 1) enters the inside of the light guide plate 12 through the incident surface 12A, and the illumination light is emitted between the back surface 12B and the emission surface 12C. It propagates inside the light guide plate 12 while repeating reflection. At this time, each time the illumination light is reflected by the back surface 12B, the light scattering surface 2 formed on the back surface 12B.
A component having a critical angle or less with respect to the emission surface 12C which is scattered by D and increases as a result is emitted from the emission surface 12C.
At this time, with respect to the illumination light, the blue illumination light is corrected to the white illumination light by the wavelength conversion sheet 6 arranged on the emission surface 12C.

When the light emitting diode 7 enters the light guide plate 12 in this manner, the illumination light emitted from the light emitting diode 7 (FIG. 2) is emitted toward the front direction of the light emitting diode 7 with a sharp directivity. As a result, in the sidelight type surface light source device 1 having the conventional configuration, when the distance from the light emitting diode 7 is increased along the incident surface, the amount of emitted light emitted from the emitting surface 12C is reduced, and uneven brightness is observed.

On the other hand, in this embodiment,
In the groove 13 formed on the incident surface 12A, the groove 13
Illumination light L incident on the slopes 13A and 13B forming the
However, the optical paths are bent by the slopes 13A and 13B, respectively, and are distributed to both side surfaces of the light guide plate 12. That is, as shown in FIG. 2, the groove 13 on the front surface of the light emitting diode 7
As an example, the groove 13 on the front side distributes the illumination light L to the areas ARA and ARB. In addition, the grooves on both sides from the front face the areas ARA and ARB.
The illumination light L is distributed to an area further outside of the light guide plate 12, so that the light guide plate 12 compensates for the insufficient amount of the illumination light L between the light emitting diodes 7 and reduces the uneven brightness on the emission surface.

Further, when the illumination light L is distributed in this way, the illumination light L incident between the slopes 13A and 13B.
The area ARM between the areas ARA and ARB in which the optical path is bent by the curved surface 13C connecting the slopes 13A and 13B, and the illumination light L is distributed by the slopes 13A and 13B.
Be assigned to. At this time, in this area ARM, since the slopes 13A and 13B are smoothly connected by the curved surface 13C, the areas ARA, ARM, ARB
It is possible to prevent a rapid change in the amount of the illumination light L at the boundary of, so that it is possible to effectively avoid the occurrence of luminance unevenness due to the connection portion of the slopes 13A and 13B. Thus, as in this embodiment, if a groove is formed by directly connecting the slopes of the flat surface, a streak-like bright line corresponding to the connecting portion of the slopes is observed from the emission surface, and the quality of the emitted light is increased by that amount. Was found to decrease.

Similarly, between the slopes of the adjacent grooves 13, the curved surfaces 14 are also smoothly connected to each other, so that the illumination light L entering between the grooves 13 can also have an optical path so that the boundary between the grooves 13 becomes inconspicuous. Is bent, so that the deterioration of the quality of the emitted light is effectively avoided.

According to the above construction, the groove 13 extending from the exit surface 12C to the back surface 12B is repeatedly formed on the entrance surface 12A, and the slopes 13A and 13B are smoothed by the curved surface 13C.
By forming the groove 13 by connecting to the above , the illumination light L can be distributed to both side surfaces of the light guide plate 12 and incident on the light guide plate 12. As a result, it is possible to compensate for the insufficient light amount of the illumination light L between the light emitting diodes 7 and reduce uneven brightness along the incident surface 12A. Also slopes 13A and 13B
It is possible to effectively avoid the occurrence of uneven brightness due to the connection part of
It is possible to effectively avoid the deterioration of the quality of the emitted light.
You can

[0034]

(2) Second Embodiment FIG. 3 is a partially enlarged view of the light guide plate showing the groove shape in an emphasized manner in comparison with FIG. In the sidelight type surface light source device according to the second embodiment, the light guide plate 22 is applied instead of the light guide plate 12 described with reference to FIG. The light guide plate 22 is formed in the same manner as the light guide plate 12 described above with reference to FIG. 1 except for the configuration of the incident surface 22A, and thus the illumination surface is repeatedly reflected and propagated between the back surface and the emission surface while the emission surface is being emitted. It is designed to emit more.

In the light guide plate 22, the grooves 13 of the same shape are repeatedly formed only in the region facing the emission surface of the light emitting diode 7, and these grooves are smoothly connected by the curved surface 14.

According to the structure shown in FIG. 3, even if the groove 13 is formed only in the region facing the emitting surface of the light emitting diode 7, the same effect as that of the first embodiment can be obtained. . In addition, since the groove 13 is formed only in the region facing the emission surface of the light emitting diode 7, the period required for producing the mold of the light guide plate 22 can be shortened as compared with the first embodiment.

(3) Third Embodiment FIG. 4 is a partially enlarged view of the light guide plate showing the groove shape in an emphasized manner in comparison with FIG. In the sidelight type surface light source device according to the third embodiment, the light guide plate 23 is applied instead of the light guide plate 12 described above with reference to FIG. The light guide plate 23 is formed in the same manner as the light guide plate 12 described above with reference to FIG. 1 except for the configuration of the entrance surface 23A, and thus the illumination surface is repeatedly reflected and propagated between the back surface and the exit surface while the exit surface is being emitted. It is designed to emit more.

The light guide plate 23 has a groove 13 on the incident surface 23A.
Are repeatedly formed, and the grooves 13 are smoothly connected by the curved surface 14. Further, these grooves 13 have the deepest depth at the portion corresponding to the center of the light emitting diode 7 which is a point light source, and the depths are gradually reduced as the distance from the center increases.

Accordingly, in the light guide plate 23, in the portion corresponding to the center of the light emitting diode 7 having the largest incident light amount, the groove 13 adjacent to the illumination light L bent by the pair of slopes forming the groove 13 is as close as possible. It is arranged that the illumination light is distributed to both side surfaces so as not to traverse, and the multiple reflections of the illumination light caused by traversing the adjacent grooves 13 are effectively avoided, and the illumination light can be efficiently distributed.

According to the structure shown in FIG. 4, the depth is sequentially reduced as the distance from the portion corresponding to the center of the light emitting diode 7 is increased, and the plurality of grooves 13 are formed in the incident surface 23A. In addition to the effect of the above form, the illumination light can be distributed more efficiently, and the luminance unevenness can be efficiently reduced accordingly.

(4) Fourth Embodiment FIG. 5 is a partially enlarged view of the light guide plate showing the groove shape in an emphasized manner in comparison with FIG. In the sidelight type surface light source device according to the fourth embodiment, the light guide plate 24 is applied instead of the light guide plate 12 described with reference to FIG. The light guide plate 24 is formed in the same manner as the light guide plate 12 described above with reference to FIG. 1 except for the configuration of the incident surface 24A.

On the incident surface 24A of the light guide plate 24, the grooves 13 are formed only in the region facing the emission surface of the light emitting diode 7, and these grooves 13 have the maximum depth at the portion corresponding to the center of the light emitting diode 7. The depth becomes deeper, and the depth gradually decreases as the distance from the center increases.

According to the structure shown in FIG. 5, the groove 13 is formed only in the region facing the emission surface of the light emitting diode 7, and the depth of this groove is further increased as the distance from the portion corresponding to the center of the light emitting diode 7 increases. By sequentially reducing the depth, in addition to the effect of the first embodiment, the illumination light can be distributed more efficiently, and the luminance unevenness can be efficiently reduced accordingly.

(5) Fifth Embodiment FIG. 6 is a partially enlarged view of the light guide plate showing the groove shape in comparison with FIG. In the sidelight type surface light source device according to the fifth embodiment, the light guide plate 25 is applied instead of the light guide plate 12 described above with reference to FIG. The light guide plate 25 is formed in the same manner as the light guide plate 12 described above with reference to FIG. 1 except for the structure of the incident surface 25A.

On the incident surface 25A of the light guide plate 25, a region facing the emission surface of the light emitting diode 7 is formed in a concave shape when viewed from the emission surface side, and the groove 13 of the same shape connected by the curved surface 14 is formed in the concave portion. It is configured to be repeatedly formed including 26. As a result, in the light guide plate 12, the lens surface of the cylindrical lens that spreads the illumination light L only on both side surfaces and guides it into the inside of the light guide plate 25 is formed by the concave portion 26, and this lens surface together with other portions of the incident surface 25A, The minute groove 13 is formed.

According to the structure shown in FIG. 6, the region facing the emitting surface of the light emitting diode 7 is formed in a concave shape when viewed from the emitting surface side, and the minute groove is formed in the concave portion 26 together with the other portion of the incident surface 25A. By forming 13, the illumination light can be more efficiently distributed to both side surfaces, and the uneven brightness can be reduced.

(6) Sixth Embodiment FIG. 7 is a partially enlarged view of the light guide plate showing the groove shape in an emphasized manner in comparison with FIG. In the sidelight type surface light source device according to the sixth embodiment, the light guide plate 27 is applied in place of the light guide plate 12 described above with reference to FIG. 1, and the light guide plate 27 is provided except for the configuration of the incident surface 27A. It is formed in the same manner as the light guide plate 12 described above with reference to FIG.

On the incident surface 27A of the light guide plate 27, a region facing the emission surface of the light emitting diode 7 is formed in a concave shape as viewed from the emission surface side, and the groove 13 having the same shape is repeatedly formed only in the concave portion 26. It is designed to be done.

According to the structure shown in FIG. 7, the region facing the emitting surface of the light emitting diode 7 is formed in a concave shape when viewed from the emitting surface side, and the minute groove 13 is formed in the concave portion 26, so that it is even further enhanced. Illumination light can be efficiently distributed to both side surfaces to reduce uneven brightness.

(7) Seventh Embodiment FIG. 8 is a partially enlarged view of the light guide plate showing the groove shape in an emphasized manner in comparison with FIG. In the sidelight type surface light source device according to the sixth embodiment, the light guide plate 28 is applied in place of the light guide plate 12 described above with reference to FIG. 1, and the light guide plate 28 except for the configuration of the incident surface 28A. It is formed in the same manner as the light guide plate 12 described above with reference to FIG.

On the incident surface 28A of the light guide plate 28, a region facing the emission surface of the light emitting diode 7 is formed in a concave shape as viewed from the emission surface side, and only the concave portion 26 has the groove 1
3 is repeatedly formed. Further, these grooves 13 are formed so that the depth thereof is gradually reduced as the distance from the portion corresponding to the center of the light emitting diode 7 increases.

According to the structure shown in FIG. 8, the region facing the emitting surface of the light emitting diode 7 is formed in a concave shape when viewed from the emitting surface side, the minute groove 13 is formed in this concave portion 26, and further, this groove is formed. By changing the depth, the illumination light can be efficiently distributed to both side surfaces, and the uneven brightness can be further reduced.

(8) Other Embodiments In the above-described embodiments, the case where the groove is simply formed on the incident surface has been described, but the present invention is not limited to this.
For example, the incident surface having the groove may be formed as a light diffusing surface by a matte surface treatment or a roughening treatment such as ink adhesion. By doing so, the illumination light can be more efficiently distributed to both side surfaces.

Further, in the above-mentioned embodiments, the case where the point light source is constituted by the light emitting diode sealed in the rectangular resin package has been described, but the present invention is not limited to this, and the light emitting diodes of various shapes are described. Therefore, it can be widely applied in the case of forming a point light source. In this case, for example, a groove may be formed on the entire surface of the incident surface as in the above-described first embodiment, or a groove may be formed partially, and further, the depth of the groove may be changed. Good. Furthermore, FIG.
As shown in, the light guide plates according to the first to sixth embodiments described above can be applied to, for example, a light emitting diode having a dome-shaped tip. Note that, in FIG. 9, a concave portion 26 is formed in the light guide plate 29 so as to correspond to the outer shape of the light emitting diode 7A, and a groove is formed on the incident surface including the concave portion 26.

Further, in the above-mentioned embodiment, the case where the flat inclined surface is smoothly connected by the curved surface to form the groove has been described, but the present invention is not limited to this, and the inclined surface is formed by the curved surface. Good.

Further, in the above-mentioned embodiments, the case where the textured surface is formed on the back surface of the light guide plate to form the light scattering surface is described, but the present invention is not limited to this, and the back surface of the light guide plate or the reflection sheet is formed. The present invention can be applied to a case where ink is adhered to form a light scattering surface, and further, it can be widely applied to a case where a light scattering sheet or the like is arranged to form a light scattering surface.

Further, in the above-mentioned embodiment, the case where the blue light emitting diode is used as the point light source and the blue illumination light is corrected to the white light by the wavelength conversion sheet on the emission surface has been described. Not limited to this, when the point light sources of various colors are used and the illumination light of this point light source is directly emitted from the light guide plate, or when the wavelength conversion sheet is used to emit the illumination light of a desired hue. Can be widely applied to.

Further, in the above-described embodiment, the case where the illumination light is incident from one end face has been described, but the present invention is not limited to this, and the side light type surface having a configuration in which the illumination light is incident from another end face as well. It can be widely applied to a light source device.

Further, in the above-mentioned embodiment, the case where the present invention is applied to the side light type surface light source device using the light guide plate made of a flat plate-shaped member has been described, but the present invention is not limited to this. The present invention can be widely applied to a sidelight type surface light source device using a light guide plate having a wedge-shaped cross section.

Furthermore, in the above-described embodiment, the case where the present invention is applied to the surface light source device of the liquid crystal display device has been described, but the present invention is not limited to this, and is a side light type such as various lighting devices and display devices. It can be widely applied to surface light source devices.

[0062]

As described above, according to the present invention, by forming a plurality of grooves extending from the emission surface to the back surface in at least the area of the incident surface of the plate-like member facing the point light source, Illumination light can be distributed to both side surfaces, which can reduce uneven brightness near the incident surface.

[Brief description of drawings]

FIG. 1 is a perspective view showing a light guide plate applied to a sidelight type surface light source device according to an embodiment of the present invention.

FIG. 2 is a plan view for explaining the operation of grooves in the light guide plate of FIG.

FIG. 3 is a plan view showing a light guide plate applied to a sidelight type surface light source device according to a second embodiment by contrast with FIG.

FIG. 4 is a plan view showing a light guide plate applied to a sidelight type surface light source device according to a third embodiment in comparison with FIG. 2.

FIG. 5 is a plan view showing a light guide plate applied to a sidelight type surface light source device according to a fourth embodiment by contrast with FIG.

FIG. 6 is a plan view showing a light guide plate applied to a sidelight type surface light source device according to a fifth embodiment in comparison with FIG. 2.

FIG. 7 is a plan view showing a light guide plate applied to a sidelight type surface light source device according to a sixth embodiment by contrast with FIG.

FIG. 8 is a plan view showing a light guide plate applied to a side light type surface light source device according to a seventh embodiment by contrast with FIG.

FIG. 9 is a perspective view showing a light guide plate applied to another embodiment.

FIG. 10 is an exploded perspective view showing a conventional side light type surface light source device.

11 is a cross-sectional view of FIG. 10 taken along the line AA.

FIG. 12 is a plan view showing the back surface of the light guide plate 2.

[Explanation of symbols]

1 ... Sidelight type surface light source device, 2, 12, 22-2
5, 27-29 ... Light guide plate, 2A, 12A, 22A-2
5A, 27A to 29A ... Incident surface, 3 ... Primary light source, 4
...... Reflective sheet, 6 …… Wavelength conversion sheet, 7,7A ……
Light-emitting diode, 13 grooves, 13A, 13B ... Slope, 1
3C, 14 ... curved surface, 26 ... concave portion

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Claims (3)

(57) [Claims] 1. A side light type surface light source device in which illumination light emitted from a point light source is incident from an end face of a plate-shaped member, and the illumination light is bent and emitted from an emission surface of the plate-shaped member. member, the region facing the point light source of at least the end face, have a plurality of grooves extending in the emission surface which faces than the exit surface, the groove, inclined obliquely with respect to the end face 1 pair by plane or curved surface
A side light type surface light source device, characterized in that the slopes of the are connected smoothly by curved surfaces . 2. The depth of each of the plurality of grooves is gradually reduced as the distance from the center of the point light source increases.
Side light type surface light source device according to formed in claim 1, characterized in such that. 3. The plate-shaped member covers the entire area facing the point light source when viewed from the emission surface side.
The sidelight type surface light source device according to claim 1 or 2, wherein a part or a part is formed in a concave shape .