JP2001060410A - Sheet-like light source unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve non-uniformity of brightness of light in a sheet-like light source unit of an edge light system using a point light source such as an LED as a light source. SOLUTION: In a sheet-like light source unit 10 provided with a plate-like translucent, light guide member 1 and a point-like light source 2, the light guide member 1 consists of a light emitter 11 having a quadrilateral plane and an optical path converter 12 formed into an asymmetric triangular shape and connected to the light emitter 11. The lower surface 11a of the light emitter 11 serves as a light diffusing surface and the upper surface 11b thereof serves as a light emitting surface, so that light from the light source 2 is laterally assigned to the optical path converter 12, and further, a reflector 6 is disposed together with a through hole 8 or a blind hole having the function of partly transmitting the light. Consequently, the light from the light source 2 is uniformly enlarged by the optical path conversion, and then, radiates the upper and lower surfaces of the light emitter 11, so that sheet-like lighting light 9 can be emitted at uniform brightness from the emitting surface 11b, wherein space efficiency can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar light source unit of a display device having a backlight mechanism for illuminating a transmissive or transflective panel from the back.

[0002]

2. Description of the Related Art In recent years, book-type word processors and computers, portable telephones, small-sized portable telephones such as portable TVs, and the like.
2. Description of the Related Art As a display device of a thin information device, a liquid crystal display device having a thin and easy-to-see backlight mechanism is used. As such a backlight mechanism, a planar light source that irradiates the liquid crystal panel from behind to the entire surface is used. As the planar light source, a fluorescent lamp, which is a linear light emitting source, and a luminous flux of the liquid crystal panel are used. In general, a light guide plate that converts light into a planar light beam to be irradiated has been used.
Plural LEDs (light emitting diodes) instead of fluorescent lamps as linear light sources for the purpose of further thinning and longer life
Are arranged in a line.

FIGS. 5 and 6 show a planar light source unit for an edge light type panel having an LED (light emitting diode) array light source as an example of such a conventional backlight mechanism. FIG. FIG. 6 is a perspective view, and FIG. 5 and 6, reference numeral 110 denotes a planar light source unit, which includes a light guide member 101 and a plurality of LEDs 102 linearly arranged as a light source. The light guide member 101 has a plate-like and substantially rectangular parallelepiped shape made of a light-transmitting member such as a transparent plastic material. One of the wide surfaces is a light-emitting surface 101b, and a surface facing the light-emitting surface 101b has As means for reflecting light from the light source toward the opposing light emitting surface, a light diffusing surface 101a such as a plurality of minute embosses or a plurality of hemispherical dots is formed on the surface.

Further, a reflection plate 103 such as a white sheet is provided near the light diffusion surface 101a. The light emitted from the LED 102 enters the light guide 101, and most of the light undergoes total reflection on the upper surface (light emitting surface) 101b, total reflection on the lower surface, or scattering by the light diffusing surface 101a such as grain or hemispherical dot once. Alternatively, the light is emitted from the upper surface to the outside after performing a plurality of times. At this time, a part of the light is transmitted through the lower surface and enters the reflection plate 103. However, the light is reflected here and enters the light guide member 101 again, and is emitted from the upper surface to the outside directly or after being reflected. The light emitted to the outside passes through the liquid crystal panel 107 to illuminate. In order to ensure the uniformity of the luminance in the surface to be illuminated, the roughness of the grain in the lower surface is adjusted, and the shape and density of the hemispherical dots are changed depending on the location.

[0005]

However, the above-mentioned planar light source unit has the following problems. That is, the roughness of the grain is adjusted, the shape of the hemispherical dot,
Some uniformity of in-plane luminance can be adjusted by changing the density depending on the location, but there is a limit to this, and light emitted from one side of the side surface of the light guide member is limited. It is necessary to use a linear light source having uniformity. In order to realize this, it is necessary to arrange a plurality of point light sources such as LEDs so as to approximate the linear light source. That is, if there is only one LED, the intensity of light emission greatly changes depending on the direction due to the directivity.
The effect appears as a non-uniform distribution of the luminance of the illumination light, making uniform illumination impossible. Therefore, many L
There is a problem that an ED is required, which leads to an increase in cost and an increase in current consumption.

An object of the present invention is to improve the above-mentioned problems in the prior art. The present invention solves the above-described problem, and enables one or a small number of LEDs close to a point light source to be used as a light source in an edge light type planar light source unit to emit a uniform planar light flux. The purpose is to do. Further, the present invention relates to a portable information device such as a portable TV and a portable telephone,
It is another object of the present invention to increase the efficiency of planar arrangement of components including a planar light source unit and a speaker and the like disposed in proximity to the planar light source unit, and to contribute to miniaturization of the planar shape of these information devices. Accordingly, it is possible to provide a planar light source unit in which the illumination light is uniform, the cost and power consumption of the light source are reduced, the cost is low, and the planar arrangement efficiency is high.

[0007]

According to a first aspect of the present invention, there is provided a light emitting member having a plate-like shape formed of a light-transmitting material and having a quadrilateral light emitting surface on a first main surface. Has,
An edge light type planar light source unit comprising: a light guide member provided with a light diffusing means on a second main surface opposite to the first main surface; and a light source arranged close to a side surface of the light guide member. In the light guide member, adjacent to the portion having the light exit surface, has an optical path conversion portion having a plane shape of an asymmetric triangle or asymmetric quadrilateral close to the center line of the light exit surface, One or more through-holes or blind holes having a function of refracting and reflecting the light emitted from the light source in the light path conversion part are provided, and reflection parts are provided on both sides of the part facing the light source on the side surface of the light path conversion part. It is characterized by having.

According to a second aspect of the present invention, in the first aspect, the planar shape of the optical path conversion portion is obtained by cutting off a part of an acute vertex of a right triangle. An asymmetric deformed quadrilateral having bent sides, wherein the light source is arranged to face the cut-out side.

According to a third aspect of the present invention, there is provided the light emitting device according to the first or the second means, wherein the reflecting portion on the side surface of the optical path changing portion has a sharp vertex of the right triangle. The light guide member is provided on a side surface of the light guide member on both sides of a side formed by cutting off a corner, and includes a plurality of substantially arc-shaped grooves substantially parallel to a thickness direction of the light guide member.

According to a fourth aspect of the present invention, as a fourth means for solving the above-mentioned problem, in the third means, the substantially arc-shaped groove of the reflecting portion on the side surface of the optical path changing portion is denser as the distance from the light source increases. It is characterized by being arranged.

According to a fifth aspect of the present invention, there is provided the light guide member according to any one of the first to fourth means, wherein the light guide member has a side surface having a light exit surface. The light scattering means may be provided on one side close to the light source, the light scattering means comprising a grain or a depression of a plurality of hemispherical dots.

According to a sixth aspect of the present invention, there is provided a light-emitting device according to any one of the first to fifth means, wherein the light is provided on a second main surface of the light-guiding member. The diffusion means is a grain or a depression of a plurality of hemispherical dots.

According to a seventh aspect of the present invention, there is provided the light guide member according to any one of the first to sixth means, wherein the light guide member has the quadrilateral light exit surface. The optical path conversion unit is provided so as to be connected to the longer side of the portion.

According to an eighth aspect of the present invention, there is provided the light guide member according to any one of the first to sixth means, wherein the light guide member has the quadrilateral light exit surface. The optical path conversion unit is provided so as to be connected to the shorter side of the portion.

According to a ninth aspect of the present invention, in order to solve the above-mentioned problems, in any one of the first to eighth aspects, the light source is an LED.

According to a tenth aspect of the present invention, there is provided a display device using the planar light source unit according to any one of the first to ninth aspects. A component other than the planar light source unit is disposed at a position facing the longer side surface of the side surfaces on both sides of the light path conversion portion of the member facing the light source.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The present embodiment relates to a planar light source unit including a light guide member having a through-hole for distributing incident light to the left and right and an LED facing the through-hole. FIG. 1 is a perspective view showing the configuration of the planar light source unit according to the present embodiment. In FIG.
Is a planar light source unit, and a light guide member 1 and a light source L
It is constituted by the ED 2 and the reflection plate 3.

The light guide member 1 is made of a light transmitting material such as an optical plastic material, has a plate shape, and has a plane shape of a quadrangle A1A2.
An A3A4 light emitting portion 11 and an optical path changing portion 12 having a substantially right-angled triangular planar shape are formed. One side (A3-A4) of the quadrilateral of the illuminating light emitting portion 11 is formed at the same time by a substantially right angle of the optical path changing portion 12. As if it is one side of the right angle of the triangle,
The light emitting unit 11 and the optical path changing unit 12 are connected. In the embodiment shown in FIG.
Are formed integrally by injection molding or the like, but they may be formed separately and then joined together to form the light guide member 1.

The upper surface of the light emitting portion 11 has a smooth light emitting surface 11b, and the lower surface 11a of the light emitting portion opposite to the light emitting surface 11b has a plurality of micro-textures or recesses of a plurality of hemispherical dots on its surface. And the like. The protruding portion of the optical path conversion unit 12 is chamfered to form a chamfer 12c. Reference numeral 5 denotes an incident portion, which is provided in the chamfered portion 12c and forms a semicircular escape portion. Reference numeral 2 denotes an LED, which is held on the LED substrate 13. The LED substrate 13 is joined to the chamfered portion 12c such that the LED 2 is disposed in the escape portion of the incident portion 5.

The optical path changing portion 12 has a through hole 8 having a substantially inverted triangular planar shape having a function of refracting and reflecting light.
Is provided substantially directly above the LED 2. And through hole 8
Is a portion corresponding to a vertex of a triangle facing the LED 2 (between p1 and p2), a tip curved surface 8b forming a rounded curved surface
The reflective side surfaces 8a1 and 8a2 facing the LED 2 are provided on both sides of the tip curved surface 8. Reflective side surface 8a
1, 8a2 can be a paraboloid. In this case, light coming out of the focus of the paraboloid collides with the axis of the paraboloid due to total reflection when hitting the paraboloid. Therefore, LED2
Is disposed near the common focal point of the reflecting side surfaces 8a1 and 8a2, the light reflected on these reflecting side surfaces can be distributed to the left and right as almost parallel rays. The through hole 8 is provided with a flat bottom side surface 8c facing the tip curved surface 8b.

The chamfered portion 12c provided with the incident portion 5
On the side surfaces 12d1 and 12d2 on both sides of the mirror, a reflecting portion 6 formed of a plurality of arc grooves parallel to the thickness direction is formed. The grooves of the reflection part 6 are arranged denser as the distance from the LED 2 of the light source increases. Although the reflecting portion shown in this example is formed of a circular arc groove, a reflecting portion may be formed by forming a rough surface or the like that causes irregular reflection partially or entirely on the side surface instead. Light emitting portion 1 on extension of side surface 12d1
The one side surface 11d may be a light diffusing surface having a plurality of minute grains or a plurality of hemispherical dot dents on its surface.

The arrangement of the reflector 3 such as a white sheet close to the lower surface 11a of the light emitting portion 11 is the same as in the prior art. The reflecting plate 3 reflects the light leaked to the outside from the lower surface 11a of the light emitting portion and emitted therefrom.
1 again. The same effect can be obtained by attaching a silver vapor-deposited film or the like to the light diffusion surface 1a on the lower surface of the emission part instead of the reflection plate 3. Although not shown, if necessary, the reflecting member 6 is formed of a reflecting sheet or a silver vapor deposition by opposing or contacting the side surface 12d1, 12d2 or another side surface on which the reflecting portion 6 formed of the arc groove is formed. Can also be provided. In addition to the above-described inverted triangular through-holes 8, a plurality of through-holes or blind holes (not shown) are formed at desired positions on the left and right sides, and the direction of light emission can be freely adjusted. Note that LEDs 2 used in the present embodiment are R, G, B
LED of any one of
It may be an ED.

The operation of the planar light source unit according to the present embodiment having the above configuration will be described. As shown in FIG. 1, the light emitted from the LED 2 enters the optical path changing part 12 of the light guide member 1 from the incident part 5, and the light incident on the curved end surface 8 b of the through hole 8 passes through the curved surface by refraction. Thereafter, the light passes through the through hole 8, passes through the opposite bottom side surface 8 c by refraction, enters the light guide member 1 again, reaches the light emitting portion 11, is totally reflected by the light emitting surface 11 b, and faces the light emitting portion 11 b The light is totally reflected or irregularly reflected by the lower surface 11a of the light-emitting portion, and finally exits from the light-emitting surface as illumination light 9 to the outside. Here, the position and the size of the tip curved surface are set so that the incident angle of light to the tip curved surface 8b is smaller than the critical angle θc (with respect to air) of the light guide member 1 even at the maximum.

The light incident on the reflection side surfaces 8a1 and 8a2 on both sides of the tip curved surface 8b of the through hole 8 is totally reflected on the side surfaces and is divided into right and left, and after being reflected by the reflection portion 6 composed of the arc groove, The light reaches the light emitting portion 11 and finally exits as illumination light 9 from the light emitting surface 11b according to the same principle as described above. A part of the light totally reflected by the reflection side surface 8a1 is incident on the side surface 11d serving as the light diffusing surface of the light emitting unit 11, and is incident on the light emitting unit 11 by diffuse reflection. Specifically, the light exits from the light exit surface 1b as illumination light 9 to the outside. Here, the reflection side surface 8
The size and shape of the reflective side surfaces 8a1 and 8a2 are set so that the incident angle of light with respect to a1 and 8a2 is larger than the critical angle θc (with respect to air) of the light guide member 1 even when the incident angle is minimum. Note that the brightness of the light incident on the reflector 6 tends to decrease as the distance from the LED increases due to the solid angle. However, as described above, the density of the plurality of grooves of the reflection unit 6 is the LED.
2, the brightness of the light reflected from the reflector 6 into the light guide member 1 does not decrease even near the left and right ends thereof.

Of the light emitted from the LED 2 and incident from the incident portion 5, the light that escapes from the through hole 8 and enters on both sides thereof reaches the illuminating light emitting portion 11 directly, and finally, by the same principle as described above. The light exits from the light exit surface 1b as illumination light 9 to the outside. In this manner, the light that has entered the optical path changing portion 12 of the light guide member 1 from the LED 2 via the incident portion 5 is
The light exits from the light exit surface 11b through various types of routes and becomes illumination light as a whole. The light emitted through each route has the following characteristics.

That is, light passing through the tip curved surface 8b is light of the first route, light reflected by the reflection side surfaces 8a1 and 8a2 is light of the second route, and light incident on both sides of the penetrating hole 8 which is out of the through hole 8. Is the light of the third route, the luminance of the illumination light 9 from the light emitting surface 1b by the light of the first route is large at the center of the light emitting surface 11b and small at both sides. The luminance of the outgoing light 9 from the light exit surface 11b due to the light of the second route is small at the center of the light exit surface 11 and large at both sides. The luminance of the outgoing light 9 from the light exit surface 11b due to the light of the second route is small at the center of the light exit surface 11b and large at both sides. Therefore, by appropriately selecting the ratio of the amount of light of the first route to the amount of light of the second and third routes, the characteristics of the luminance are complemented with each other, so that the light emission is achieved. The brightness of the emitted light for illumination over the entire surface 11b can be uniform or substantially uniform.

The balance of the luminance can be achieved by, for example, appropriately selecting the dimensional ratio between the curved surface 8b of the tip of the through hole 8 and the reflective side surfaces 8a1 and 8a2 and the distance between the side surfaces 12d1 and 12d2 and the through hole 8. Can be achieved. Also, at this time, in order to make the luminance of the illumination light uniform, the roughness of the light diffusing surface on the lower surface 11a of the light emitting portion 11 which is the lower surface of the light emitting portion 11 is changed, and the shape and density of the concave portion of the hemispherical dot are changed. Changing according to the place has the same effect as the prior art.

Next, the configuration of a display device using the planar light source unit according to the present invention will be described with reference to the drawings.
2A and 2B are diagrams showing a configuration of a main part of a liquid crystal display device using the planar light source unit 10 shown in FIG. 1, wherein FIG. 2A is a top view and FIG. 2B is a side view. In FIG. 2, 7 is a liquid crystal panel, 15 is a speaker, and 17 is a circuit board. Here, in FIG. 2A, the liquid crystal panel 7 and the reflection plate 3 are not shown for convenience. As shown in FIG. 2 (b), the liquid crystal panel 7 is arranged above the light exit surface 11b of the light exit portion 11 of the light guide member 1, and the uniform illumination light 9 from the light exit surface 11b causes uneven brightness. There is no lighting.

The speaker 15 is mounted on the circuit board 17 on the side surface 1 corresponding to the oblique side of the optical path changing portion 12 of the light guide member 1.
It is arranged at a position facing and close to 2d2. FIG.
As shown in (a), according to the arrangement of this example, the speaker 15 can be accommodated in a space that is vacant in a plane. This is because the planar shape of the optical path conversion unit 12 forms a substantially right triangle,
This is because a considerably vacant space is created in a portion facing the hypotenuse. For reference, the alternate long and short dash line in FIG. 2A indicates the position of the outer shape when the optical path conversion unit 12 is an isosceles triangle, but in this case, it is difficult to take sufficient free space. As described above, in this example, by using the planar light source unit 1 shown in FIG. 1, the speaker 15 can be efficiently disposed in a space that is two-dimensionally vacant. Small, portable T
V, a liquid crystal display device suitable for a mobile phone or the like can be provided. The present invention is not limited to this, and transformers and other components can be efficiently arranged in the empty space.

Next, FIG. 3 is a top view showing a modification of the liquid crystal display device shown in FIG. The planar shape of the light guide member 1 of the liquid crystal display device shown in FIG.
Although the optical path conversion unit 12 is connected to the longer side A3A4 of 3A4, the planar shape of the light guide member 1 of the liquid crystal display device shown in FIG.
The optical path conversion unit 12 is connected to the shorter side A2A3 of A4. In FIG. 3, the symbols of the components of the liquid crystal display device are the same as those in FIG. 2A. As shown in FIG. 3, also in the case of this example, the speaker 15 can be stored in a space that is vacant in a plane. The case of this example is suitable for forming a liquid crystal display device having a flat shape with a relatively large aspect ratio.

Hereinafter, another embodiment of the present invention will be described with reference to the drawings. The present embodiment relates to a modification of the planar light source unit shown in FIG. 4A and 4B are diagrams showing a configuration of the planar light source unit according to the present embodiment, wherein FIG. 4A is a top view, and FIG. 4B is a cross-sectional view taken along line AA of FIG. In FIG. 4, reference numeral 4 denotes a blind hole provided in the optical path conversion unit 12 and having a substantially inverted triangular planar shape. One of the vertices of the triangle faces the LED 2, the tip is sharp, and is not rounded. . The reflection side surfaces 4a1 and 4a2 of the blind hole 4 facing the triangular LED 2 have a common focal point in a separate substantially parabolic surface, and the LED 2 is disposed near the focal point. As shown in FIG. 4B, the bottom surface 1 of the optical path conversion unit 12
2a is a light diffusing surface composed of a plurality of minute embosses or a plurality of hemispherical dots on its surface,
Under the blind hole 4, a bypass portion 12f exists between the bottom surface 4c of the blind hole 4 and the bottom surface 12a of the optical path changing portion. For other components and symbols of the components, see FIG.
It is the same as shown.

The operation of the planar light source unit according to the present embodiment having the above configuration will be described. As shown in FIG. 4A, the light emitted from the LED 2 enters the optical path changing portion 12 of the light guide member 1 from the incident portion 5, and the bypass portion is formed below the blind hole 4 as shown in FIG. The light incident on 12f is the bottom surface 4c of the blind hole 4 and the optical path changing unit
The light enters the illumination light emitting portion 11 directly or repeatedly without reflection between the bottom surfaces 12a of the second 2, and thereafter finally emits the illumination light 9 from the light emitting surface according to the same principle as described above. I do.

The light incident on the reflective side surfaces 4a1 and 4a2 of the blind hole 4 on the bypass portion 12f is shown in FIG.
As shown in FIG. 7, the light is totally reflected on the side surface and is distributed to the left and right. After being reflected by the reflecting portion 6 according to the same principle as described above, the light is finally emitted from the light exit surface 11b to the outside as illumination light 9. Inject. The light coming out of the blind hole 4 and incident on both sides directly reaches the light emitting portion 11,
The illumination light 9 is finally emitted from the light exit surface 11b to the outside according to the same principle as described above.

Here, the luminance of the illumination light due to the light passing through the bypass portion 12f is large at the center of the light exit surface 11b and small at both sides. On the other hand, the brightness of the light passing through the reflection side surfaces 4a1 and 4a2 and the luminance of the illumination light due to the light coming out of the blind hole 4 and being incident on both sides is large at the center of the light exit surface 11b and small at both sides. Therefore, by appropriately selecting the ratio of the amount of light by other routes to the amount of light passing through the bypass portion 12f, the characteristics of the luminance are complemented by each other, so that the entire light exit surface 1b , The brightness of the emitted light for illumination can be uniform or substantially uniform. Such a balance of luminance is shown in FIG.
, The ratio of the depth t1 of the blind hole 4 to the thickness t2 of the bypass portion 12f, the distance between the blind hole 4 and the LED 2, the reflection side surface 4a.
This can be achieved by appropriately selecting the 1,4a2 dimensions. The outer shape of the planar light source unit 10 of the present embodiment is the same as that of the planar light source unit 10 shown in FIG. 1, and space efficiency can be increased for the same reason.

In the embodiment of the present invention described above, a planar light source unit in which one LED is disposed on the side surface of a light guide member has been described. However, the present invention is not limited to this, and the present invention is not limited to this. For example, it is also possible to adopt a configuration in which LEDs of three colors of R, G, and B are arranged so as to overlap in the thickness direction of the planar light source unit.

[0036]

As described above, according to the present invention, 1
In an edge light type planar light source unit provided with a point shape such as a small number or a small number of LEDs, an approximately triangular light path conversion portion that is asymmetrical left and right is provided adjacent to a light output portion of a light guide member, and the light path conversion portion is provided. In addition to distributing the incident light to the left and right, while providing a through hole or blind hole having the effect of passing a part, by providing a reflection portion of the distributed light, the light from the light source, by efficient optical path conversion The illumination light is uniformly spread as a whole so that illumination light with uniform luminance can be emitted from the light emission surface of the light emission portion. Accordingly, it is possible to provide a planar light source unit in which the illumination light is uniform, the cost and power consumption of the light source are reduced, the cost is low, and the planar arrangement efficiency is high.
Then, by using such a planar unit, it is possible to provide a display device such as a liquid crystal display device having a speaker and the like, a small planar dimension and a small thickness.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a planar light source unit according to an embodiment of the present invention.

FIGS. 2A and 2B are a top view and a side view showing a configuration of a main part of a liquid crystal display device using the planar light source unit shown in FIG.

FIG. 3 is a top view showing a configuration of a main part of a modification of the liquid crystal display device shown in FIG. 2;

FIG. 4 is a top view and a cross-sectional view illustrating a configuration of a planar light source unit according to another embodiment of the present invention.

FIG. 5 is a perspective view showing a configuration of a conventional planar light source unit.

6 is a cross-sectional view of the planar light source unit shown in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light guide member 2 LED 3 reflector 4 blind hole 4 a 1, 4 a 2, 8 a 1, 8 a 2 reflective side surface 5 incident part 6 reflective part 7 liquid crystal panel 8 through hole 8 b curved tip 9 illumination light 10 planar light source unit 11 light emitting part 11 a emission Lower surface 11b Light emitting surface 11d, 12d1, 12d2 Side surface 12 Optical path conversion unit 12c Chamfered unit 12f Bypass unit 13 LED board 15 Speaker 17 Circuit board

Claims (10)

[Claims] A first plate formed of a light-transmitting material;
A light guide member having a quadrilateral light exit surface on the main surface of the light guide member and a light diffusing means provided on a second main surface opposite to the first main surface; In the edge light type planar light source unit having the light source, the light guide member is adjacent to the portion having the light output surface, and is a right-left asymmetric triangle or an asymmetric quadrilateral close to the center line of the light output surface. Having an optical path conversion portion having a planar shape of, and the light path conversion portion is provided with one or more through holes or blind holes having a function of refracting and reflecting the emitted light of the light source, and a side surface of the optical path conversion portion. A planar light source unit, wherein reflection portions are provided on both sides of a portion facing the light source. 2. The planar shape of the optical path changing portion is an asymmetric deformed quadrilateral having a side formed by cutting out a part of an acute vertex of a right triangle, and facing the side formed by cutting out. The planar light source unit according to claim 1, wherein the light source is provided. 3. A reflecting portion on a side surface of the optical path changing portion is provided on a side surface of the light guide member on both sides of a side formed by cutting off an acute apex angle of the right triangle, and is provided in a thickness direction of the light guide member. The planar light source unit according to claim 1, comprising a plurality of substantially arc-shaped grooves substantially parallel to each other. 4. The planar light source unit according to claim 3, wherein the substantially arc-shaped grooves of the reflecting portion on the side surface of the optical path changing portion are arranged denser as the distance from the light source increases. 5. A light scattering means comprising a grain or a depression of a plurality of hemispherical dots is provided on one of the side surfaces of the light guide member having the light emitting surface, the side surface being close to the light source. The planar light source unit according to any one of claims 1 to 4, wherein: 6. The light guide member according to claim 1, wherein the light diffusing means provided on the second main surface of the light guide member is a grain or a depression of a plurality of hemispherical dots. The planar light source unit as described in the above. 7. The light guide member according to claim 1, wherein the light guide member is connected to a longer side of the portion having the quadrangular light exit surface, and the optical path conversion unit is provided. The planar light source unit according to any one of the above. 8. The light guide member according to claim 1, wherein the light guide member is connected to a shorter side of the portion having the quadrangular light exit surface, and the optical path conversion unit is provided. The planar light source unit according to any one of the above. 9. The planar light source unit according to claim 1, wherein the light source is an LED. 10. A display device using the planar light source unit according to claim 1, wherein a side surface of both sides of a portion of the light guide conversion member facing the light source in an optical path changing portion. A display device characterized by disposing other components other than the planar light source unit at a position facing the longer side surface of the display device.