JPH10177807A - Surface emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To acquire a surface emitting device whose light emitting surface can be brighter. SOLUTION: A surface emitting device 14 which makes a plane 24a emit, the light emitting surface of light guide 21, by the incident rays emitted from a light source 22 provide in opposite to an edge 21a on the light guide 21 for a plane face emitting through the edge 21a, is preconditioned. Setting the edge 21a of the light guide 21 diagonally, the center of light source 22 is positioned on the normal A of that edge 21. Hence, the most of light going into the edge 21a of the light guide 21 from the light source 22 does not travel straightly in parallel to the plane 24a and 24b of the light guide 21, thereby increasing the number of reflections of light on the plane 24a and 24b of the light guide 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light emitting device used for various liquid crystal display devices with a backlight or a display panel device for guidance, guidance, etc., and for emitting the display surface thereof. .

[0002]

2. Description of the Related Art For example, a backlight of a liquid crystal display device is formed by a surface light emitting device, and this device includes a light guide having a light guide flat plate for surface light emission and a light source. Is shown in

In FIG. 9, 1 is a light guide, 2 is a light source, and 3 is a reflecting mirror. The light guide 1 is provided with a light diffusion / reflection layer 5 having a uniform thickness on one surface (light emitting surface) 4a of the light guide plate 4 which emits light and on the other surface 4b on the opposite side. The reflection layer 5 is made of a white paint or a white sheet. End face 1 of this light guide 1
“a” is formed by a surface which is perpendicular to the planes 4a and 4b, and one light source 2 is disposed opposite to the end surface 1a. The reflecting mirror 3 is an arc-shaped reflecting surface having a radius at the center of the light source 2 or a rectangular shape (not shown).
A part of the light radiated from is reflected and made incident on the end face 1a.

In the surface light emitting device having such a configuration, the light emitted from the light source 2 is incident on the end face 1a of the light guide 1 and reflected by the light guide 1 so that the plane 4a of the light guide 1 is changed. It emits light.

[0005]

However, in the configuration of the surface light emitting device shown in FIG. 9, most of the light incident on the flat plate 4 of the light guide 1 from the light source 2 without passing through the reflecting mirror 3 is The light travels in the flat plate 4 substantially parallel to the two flat surfaces 4a and 4b, and the number of reflections on the flat surfaces 4a and 4b is small. Therefore, there is a problem that the brightness of the flat surface 4a, which is the light emitting surface of the light guide 1, is low.

Therefore, a first object of the present invention is to provide a surface light emitting device capable of increasing the brightness of a light emitting surface.

Further, in the configuration of the surface light emitting device shown in FIG.
Since the incident angle of light with respect to a is not controlled at all, the light escapes to the outside on the plane 4a and is easily attenuated in the light guide direction, and the light incident into the light guide 1 is reflected far away from the light source 2. Difficult to reach while letting. In addition, light having a large energy is strongly diffusely reflected by the light diffusion / reflection layer 5 on the side closer to the light source 2 in the light guide 1 due to such circumstances, whereas it is attenuated on the side farther from the light source 2. Since the light whose energy is reduced is weakly diffusely reflected by the light diffusion / reflection layer 5, the diffuse reflection of the light by the light diffusion / reflection layer 5 is not uniform in each part. For this reason, there is a problem that the luminance of the light emitting surface is higher as being closer to the light source 2 and lower as being farther from the light source 2.

Accordingly, a second object of the present invention is to provide a surface light emitting device which can achieve the above first object and can make the luminance of the light emitting surface uniform.

Moreover, in the configuration of the surface light emitting device shown in FIG. 9, only one light source 2 is disposed so as to face the vertical end surface 1a forming the light incident surface of the light guide 1.
The amount of incident light is small, and the number of times the incident light is reflected by the diffuse reflection layer 5 as described above is small. Therefore, there is a problem that the brightness of the flat surface 4a, which is the light emitting surface of the flat plate 4, is low.

Accordingly, a third object of the present invention is to provide a surface light emitting device which has a large effect of brightening a light emitting surface and can further improve the brightness.

Further, in the configuration of the surface light emitting device shown in FIG. 9, the incident direction of the light incident upon the reflecting mirror 3 with respect to the end surface 1a which is the light incident surface of the light guide 1 is specially controlled. Since the light is incident at various angles, the light incident through the reflecting mirror 3 cannot be efficiently diffused and reflected by the light diffusion / reflection layer 5. For this reason, there is a problem that the brightness of the plane 4a, which is the light emitting surface, is low.

Accordingly, a fourth object of the present invention is to provide a surface-emitting device capable of obtaining a reflecting mirror and effectively utilizing incident light to further improve brightness.

[0013]

SUMMARY OF THE INVENTION The present invention is directed to a planar light emitting body for surface emission, in which light emitted from a light source provided opposite to an end face of the light guide is made incident from the end face. A surface light emitting device that emits light from a light emitting surface is assumed.

In order to solve the first problem, the invention according to claim 1 is characterized in that the end surface of the light guide is an inclined surface, and the light source is arranged on a perpendicular line to the end surface. .

According to the first aspect of the present invention, most of the light incident on the end face of the light guide from the light source is obliquely incident on the light guide in advance in accordance with the angle of the inclined end face. The number of reflections in the light guide can be increased by reducing the light traveling straight in the light guide direction of the light guide.

In order to solve the second problem, the invention according to claim 2 dependent on claim 1 is characterized in that the light passing through the inclined end face is first reflected on one surface of the light guide, The acute angle θ formed by the inclined end surface is defined as θ> sin ⁻¹ n0 / n1 (where n0 is the refractive index in air and n1 is the refractive index of the light guide).

According to the second aspect of the present invention, by setting the acute angle, the light incident from the inclined end surface is totally reflected in the light guide body, and the attenuation of the light is suppressed so that the light is extended farther than the light source. Can be reached.

[0018] Similarly, in order to solve the second problem, the invention of claim 3 which depends on claim 1 or 2
The light guide is provided with a light diffusion / reflection layer for diffusing and reflecting light incident on this plane on the plane opposite to the light emitting surface, and the concentration of the light diffusion / reflection layer becomes more continuous as it approaches the inclined end face. It is a thinner one.

According to the third aspect of the present invention, due to the difference in the density of the light diffusion / reflection layer, if the light incident on the light diffusion / reflection layer is closer to the light source having a higher energy, the density of the portion which diffuses and reflects the light is lower. While the amount of light that is diffusely reflected is suppressed, the energy of the light incident on the light diffuse reflection layer is attenuated and is low. The amount of reflected light can be increased. Thereby, the luminance of the light emitting surface can be balanced in each part.

[0020] In order to solve the third problem, the invention according to claim 4 according to claim 3 is characterized in that the acute angle is located on the light diffusing reflection layer side.

According to the fourth aspect of the present invention, the light emitted from the light source and passing through the inclined end face can be first diffused and reflected by the light diffusion / reflection layer, whereby the number of times of reflection can be secured more. .

Similarly, in order to solve the third problem,
The invention according to claim 5 which depends on claims 1 to 3, wherein the end face of the light guide is inclined in opposite directions to each other with respect to a center position of the light guide in the thickness direction. And the light source is arranged so as to individually face each of the two inclined end face portions.

According to the fifth aspect of the present invention, light emitted from the two light sources can be obliquely incident on one end face of the light guide to the light guide, so that the amount of light can be increased. In addition, when the light guide distance is long, attenuation of light in the light guide direction can be compensated.

According to a sixth aspect of the present invention, in order to solve the fourth problem, a reflector for accommodating the light source is disposed so as to face the inclined end face, and the light source is set at a focal point of the reflector. It is arranged.

According to the sixth aspect of the present invention, the incident direction of the light incident on the end face, which is the light incident surface of the light guide, via the reflecting mirror is set as parallel light along the perpendicular to the end face. Can be incident on the body.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment will be described below with reference to FIGS. FIG. 1 is a cross-sectional view illustrating a configuration of a liquid crystal display device including the surface light emitting device according to the first embodiment. In this figure, reference numeral 11 denotes a main body case forming a display device main body, and a display window 11a formed on one side thereof has
It is covered with a transparent protective sheet 12 mounted on one side.

The main body case 11 contains a liquid crystal device 13, a surface light emitting device 14, a circuit device 15 for driving and controlling the liquid crystal device 13 and controlling lighting of a light source, which will be described later. The liquid crystal device 13 has a panel or film shape and is arranged to face the display window 11a. Although the specific configuration of the surface light emitting device 14 will be described later, this is used as a backlight of the liquid crystal device 13, and the liquid crystal device 13 is supported in close contact with the light emitting surface. Note that 16 in FIG. 1 are legs for supporting the surface light emitting device 14. The circuit device 15 is disposed on the back side of the surface light emitting device 14 by utilizing a space provided by the legs 16.

Next, the surface light emitting device 14 will be described.
This device 14 includes a light guide 21, a light source 22, and a reflecting mirror 2.
3 is provided.

The light guide 21 is composed of two planes 2 parallel to each other on a transparent and light guide flat plate 24 such as a transparent acrylic board.
4a and 24b, the light diffusion / reflection layer 2
5 is formed in a flat plate shape, and the other flat surface 2
4a is used as a light emitting surface. As shown in FIG. 1, the light guide 21 is brought into contact with the liquid crystal device 13 by a flat surface 24a as a light emitting surface thereof.
1.

As shown in FIG. 1 and FIG.
Is formed as an inclined surface. In the first embodiment, both end faces 21 are provided.
a are respectively inclined, and the directions of the respective inclinations are opposite to each other. This inclination causes the end of the light guide 21 to have an acute angle θ.
Is provided. These acute angles θ are preferably formed as angles between the flat surface 24b on the side of the light diffusion reflection layer 25 and the end surface 21a. This acute angle θ is equal to
In 4a and 24b, the angle is equal to or larger than the critical angle at which the light incident thereon is totally reflected, that is, θ> sin ^-1 n0 / n1 (where n0 is the refractive index in air and n1 is the refractive index of the light guide 21). .

The light diffusion / reflection layer 25 formed in such a relationship with the acute angle θ reflects the light emitted from the light source 22 and passing through the end face 21 a of the light guide 21 first. The light diffusion / reflection layer 25 is provided by printing or applying a white paint having a high light diffuse reflectance, or by attaching a white sheet.

Further, as shown in FIG. 2 and FIG. 3, the light diffusion / reflection layer 25 has a concentration of the end face 21 of the light guide 21.
It is provided so that it becomes thin continuously as it approaches a.
Therefore, as shown in FIG. 1, in the configuration in which the inclination of both end faces 21a is opposite, the density of the light guide 21 in the central part in the light guide direction is the highest, and the light guide 21 is provided continuously thinner as it approaches the end face 21a. It is what is being done. However, for example, although not shown, when the light guide 21 in which only one end face 21a of the light guide 21 is inclined and the light source 22 is provided only on this one end side is employed, the inclined one end face 21a is used.
The density may be reduced so that the density decreases from the position a to the other end face, in other words, the density increases continuously as the distance from the light source 22 increases.

The density difference can be provided in the application or printing of the white paint. In the case of application, a density difference is provided by gradually changing the thickness,
In the case of printing, it can be provided by printing a white dot and gradually changing the dot density. Further, the white sheet is used as the light diffusion / reflection layer 2.
Also in the case of producing 5, the density difference can be provided by laminating the sheets so that the thickness becomes stepwise.

As the light source 22, a cold-cathode tube which is a kind of a straight tube type fluorescent tube is used. As shown in FIGS. 1 to 4 and the like, the light source 22 is provided close to and opposed to the inclined end face 21 a of the light guide 21, and the center 22 a of the light source 22 (see FIG. 4) is located at the end face 21 a (Normal line) A (see FIG. 4).

The reflecting mirror 23 which accommodates the light source 22 is disposed near the end face 21a. A center 22a of the light source 22 is disposed at the focal point of the reflecting mirror 23, and a reflecting mirror having a parabolic reflecting surface with the center 22a of the light source 22 as a focal point is used as the reflecting mirror 23. I have. Therefore, the reflecting mirror 23 causes the light emitted from the light source 22 to the reflecting mirror side to enter the light guide 21 through the end face 21a as reflected light parallel to the normal A of the end face 21a. I have.

The liquid crystal display device having the above-described surface light emitting device 14 is used as a backlight for illuminating the liquid crystal device 13 from the back by turning on the light source 22 of the surface light emitting device 14.

In such a state of use, the end face 21 a of the light guide 21 is directly passed from the light source 22 without passing through the reflecting mirror 23.
As shown by a dotted arrow in FIG. 2, the incident light passing through the light obliquely first enters the light diffusion / reflection layer 25 provided on the plane 24b on the side where the acute angle θ of the light guide 21 is located, where the light is diffusely reflected. The light is reflected obliquely upward (in FIG. 2), and is reflected obliquely downward (in FIG. 2) on the plane 24a which is the light emitting surface of the light guide 21. Such reflection is converted into a zigzag reflection by the light guide 21. In the plane 2 of the light guide 21
4a. In addition, incident light from the light source 22 through the reflecting mirror 23 and passing through the end face 21a of the light guide 21 also
An optical path parallel to the optical path indicated by the dotted line in FIG. 2 is formed, and zigzag reflection is repeated in the light guide 21 to make the plane 24a of the light guide 21 emit light.

In the above-described surface light emission operation, as described above, most of the light incident on the oblique end surface 21a of the light guide 21 from the light source 22 depends on the acute angle θ of the inclined end surface 21a. The light is obliquely incident on the light guide 21 in advance.
Therefore, it is possible to reduce the incidence of the incident light traveling substantially parallel to the planes 24a and 24b of the light guide 21, and increase the number of reflections on the planes 24a and 24b. In addition, since the light incident on the light guide 21 is first diffused and reflected by the light diffusion / reflection layer 25, the number of reflections in the light guide 21 can be secured more, and the number of diffuse reflections of light can be increased.
Therefore, the brightness of the light emitting plane 24a of the light guide 21 can be increased, and the liquid crystal screen can of course be increased.

Further, the acute angle θ forming the inclination angle of the end surface 21a of the light guide 21 on which the light from the light source 22 is incident is equal to or larger than the critical angle, that is, θ> sin ^-1 n0 / n1, so that the inclined end surface The light incident from the light guide 21a is applied to both flat surfaces 24 of the light guide 21.
a and 24b can be totally reflected, respectively. Thus, the light does not pass through the display-side flat surface 24a from the side closer to the light source 22 and the attenuation of the incident light can be suppressed, so that the light can reach farther than the light source 22. Therefore, even when the light guide distance is long, the attenuation of light in the light guide direction can be compensated for, so that the effect of brightening the light emitting plane is great, and the brightness can be further improved, The luminance of the light emitting plane 24a can be made uniform.

In addition, due to the difference in the density of the light diffusion / reflection layer 25, the density of the portion which diffuses and reflects light is lower in the portion closer to the light source 22 where the energy of light incident on the light diffusion / reflection layer 25 is higher. While the amount of light to be diffused is reduced, on the other side of the light source 22 where the energy of the light incident on the light diffusion / reflection layer 25 is attenuated and lowered, the density of the portion that diffuses and reflects the light is high. The amount of reflected light can be increased. Therefore, this also
The luminance of the light emitting plane 24a is balanced in each part, so that the luminance can be made uniform.

In addition, as described above, the incident direction of the light incident through the reflecting mirror 23 on the end surface 21a, which is the light incident surface of the light guide 21, is parallel to the perpendicular (normal line) of the end surface 21a. Since the light is made incident on the light guide 21 as light, the light obtained by obtaining the reflecting mirror 23 is made to act similarly to the incident light directly passing through the end face 21 a of the light guide 21 without passing through the reflecting mirror 23. Available. Therefore, the emitting plane 2
The brightness of 4a can be further improved.

Further, in the first embodiment,
Since the light from the light source 23 is made incident from each of the slanted end surfaces 21a of the light guide 21, the light amount is large, and the display operation as described above is obtained by the light incident from both ends, and the light emitting surface 24a is formed. Brightness can be further increased and brightness can be equalized. Therefore, the light emitting surface 24a is suitable for a device that is desired to have high luminance, and even when the light guide distance is long, the effect of uniformly brightening the light emitting plane 24a is great.

FIG. 5 shows a main part of the second embodiment of the present invention. The second embodiment is different from the first embodiment only in the configuration of the end face of the light guide and the arrangement of the light source and the reflecting mirror with respect to the end face, and the other configurations are the same as those in the first embodiment. The configuration is the same as or similar to the surface emitting device for the liquid crystal display device of the first embodiment shown in FIGS. Therefore, the components not shown are substituted with FIGS. 1 to 4, and the same or similar components shown are given the same reference numerals as in the first embodiment, and the description of those components and the description thereof will be omitted. Although the description of the function and effect based on this is omitted, these same or similar components also constitute a part of the configuration of the surface light emitting device according to the second embodiment.

In the second embodiment, the end face 21a of the light guide is inclined in the opposite directions from the center of the light guide 21 in the thickness direction to form, for example, a mountain-shaped projection.
And the second inclined end face portions 21a1 and 21a2. And, these two inclined end face portions 21a1, 21a2
, Two light sources 22 are arranged so as to face each other. Of course, one light source 22 is arranged on the perpendicular to the inclined end face 21a1 and the other light source 22 is arranged on the perpendicular to the inclined end face 21a2.
Further, a reflecting mirror 23 which accommodates these light sources 22 and has a pair of parabolic reflecting mirror surfaces whose focal point is the center of the light sources 22 is provided correspondingly. Note that the reflecting mirror 23 may be independent for each light source 22. The configuration other than the above is the same as that of the first embodiment, including the points not shown.

Therefore, also in the second embodiment, the same operation as that of the surface light emitting device 14 of the first embodiment can be obtained, and the first, second, and fourth problems of the present invention can be obtained. Can be solved.

In addition, in the second embodiment, one end of the light guide 21 is formed by the configuration of the end face 21a of the light guide 21 and the arrangement of the pair of light sources 22 and the pair of reflectors 23 corresponding thereto. The light emitted from the two light sources 22 is obliquely incident on the light guide 21 as shown by a dotted line in FIG. Therefore, it is suitable for a case where a high luminance of the light emitting plane 24a is required, and can compensate for the attenuation of light in the light guiding direction even when the light guiding distance is long. Also suitable for.

In the second embodiment, since the continuous inclined end surfaces 21a1 and 21a2 form a mountain-shaped end surface 21a, a pair of light sources 22 opposed to the end surfaces 21a1 and 21a2 are moved away from each other to eliminate the interference. There is an advantage that it is easy to secure a space for disposing the. Note that in the second embodiment,
The other end face side (not shown) may be symmetrical with the one end side shown, but it is not oblique but a vertical face, and it is not necessary to provide a light source and a reflecting mirror. In this case, the brightness of the display surface can be further increased by further increasing the amount of light.

FIGS. 6 and 7 show a main part of a third embodiment of the present invention. This third embodiment is different from the first embodiment only in the configuration of the end face of the light guide, and the other configurations are the same as those shown in FIGS. The structure is the same as or similar to that of the surface emitting device for the liquid crystal display device of the first embodiment shown in FIG. Therefore, the configuration not shown in FIG.
4 to FIG. 4, and the same or similar components shown in the drawings are denoted by the same reference numerals as those in the first embodiment, and the description of those configurations and the description of the operation and effect based thereon are omitted. However, these same or similar components also constitute a part of the configuration of the surface emitting device according to the third embodiment.

In the third embodiment, the light guide 2
The inclination of the end face 21a is opposite to that of the first embodiment, and the acute angle θ is the angle between the plane 24a and the slope 21a forming the display surface, and the light diffuse reflection is performed. It is provided on the display surface side opposite to the surface 25. Therefore, the light from the light source passing through the end face 21a is first totally reflected by the plane 24a forming the display surface.

Therefore, also in the third embodiment, the same operation as that of the surface light emitting device 14 of the first embodiment can be obtained. Each of the first to fourth problems of the present invention can be solved, except for the solution of the third problem of the present invention in terms of increase.

FIG. 8 shows a fourth embodiment of the present invention. The fourth embodiment shows an example in which the display panel device is used. In this panel device, the configuration of the end face of the light guide and the arrangement of the light source and the reflecting mirror with respect to the end face are the same as those of the first embodiment. The other configuration is different from that of FIG.
The structure is the same as or similar to that of the surface light emitting device of the third embodiment shown in FIGS. 6 and 7 including parts not shown in FIG. Therefore, components not shown are substituted with FIGS. 6 and 7, and the same or similar components shown are given the same reference numerals as in the third embodiment, and the description of those components and the description thereof will be omitted. Although the description of the operation and effect based on this is omitted, these same or similar components also constitute a part of the configuration of the surface light emitting device according to the fourth embodiment.

In the fourth embodiment, there is provided a pair of light guides 21 each having an inclined end face 21a only at one end face, and these light guides 21 are brought into surface contact with the light diffusion / reflection layer 25 and bonded. The display panel P is combined to form a display panel P. In order to use both side surfaces as display surfaces, desired displays such as marks and characters are provided on the display surfaces by printing or engraving. The end faces 21a which are continuous with each other by the lamination form a V-shaped concave groove, and a part of the groove is housed in the groove, and one light source 22 is provided so as to be closely opposed. Of course, this light source 22 is centered on each end face 21a.
Are arranged so as to coincide with the intersections of the vertical lines (normal lines).
Then, the one light source 22 is accommodated,
A reflecting mirror 23 having one parabolic reflecting mirror surface having the center as the focal point is provided. The configuration other than the above is the same as the surface light emitting device of the third embodiment.

In FIG. 8, reference numeral 31 denotes a device main body of the display panel device. Under the lower portion, the end portions of the two light guides 21 on the end surfaces 21a side are supported.
The light source 22 and the reflecting mirror 23 are housed. further,
A circuit device 32 for adjusting the on / off of the light source 22 and the illuminance thereof is accommodated in the device main body 31. The display panel device turns on the light source 22 to tilt the two light guides 21. Light is incident on each of the end faces 21a, and the light is first totally reflected on both planes of the light guides 21 forming the display surface to guide the light zigzag, whereby the display can be displayed brightly.

Therefore, also in the fourth embodiment, the same operation as that of the surface light emitting device of the first embodiment can be obtained, so that the number of times of reflection of light by the light diffusion / reflection layer 25 is increased. Except for the solution of the third problem of the present invention, each of the first to fourth problems of the present invention can be solved.

[0055]

The present invention is embodied in the form described above and has the following effects.

According to the first aspect of the present invention, light incident on the light guide from the light source is prevented from traveling straight in the light guide direction of the light guide, and the number of reflections in the light guide can be increased. The brightness of the light emitting surface of the light guide can be increased.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, since the incident light is totally reflected inside the light guide, the brightness of the light emitting surface can be made uniform.

According to the third aspect of the invention, in addition to the effect of the first aspect of the invention, the amount of light diffusely reflected near the light source is reduced due to the density difference of the light diffusion reflection layer, and On the side farther from the light source, the amount of light diffusely reflected can be increased to make the luminance of the light emitting surface uniform.

According to the fourth aspect of the invention, in addition to the effect of the third aspect of the invention, light incident from the inclined end face is first diffused and reflected by the light diffusion / reflection layer, so that the number of times of reflection is increased. Therefore, the effect of brightening the light emitting surface is great, and the brightness can be further improved.

According to the fifth aspect of the present invention, in addition to the effects of the first to third aspects, the amount of light obliquely incident from one end face of the light guide is increased so that even when the light guide distance is long. Since the light attenuation in the light guide direction can be compensated for, the effect of brightening the light emitting surface is great, and the brightness can be further improved.

According to the sixth aspect of the present invention, in addition to the effects of the first to fifth aspects, the direction of incidence of light incident through the reflecting mirror is set as parallel light along the perpendicular to the end face. , The reflected light can be obtained and the incident light can be used effectively, so that the brightness of the light emitting surface can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a configuration of a liquid crystal display device provided with a surface emitting device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a configuration on a light incident side of the surface emitting device according to the first embodiment.

FIG. 3 is a plan view showing a configuration on the light incident side of the surface emitting device according to the first embodiment.

FIG. 4 is a sectional view showing a configuration of a light incident end of the surface emitting device according to the first embodiment.

FIG. 5 is a cross-sectional view illustrating a configuration of a light emitting unit side of a surface emitting device according to a second embodiment of the present invention.

FIG. 6 is a cross-sectional view schematically showing a configuration of a liquid crystal display device including a surface emitting device according to a third embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating a configuration on a light incident side of a surface emitting device according to a third embodiment.

FIG. 8 is a perspective view showing a configuration of a display panel device provided with a surface light emitting device according to a fourth embodiment of the present invention, partially cut away.

FIG. 9 is a cross-sectional view showing a configuration on a light incident side of a surface emitting device according to a conventional example.

[Explanation of symbols]

 Reference numeral 14 denotes a surface light emitting device, 21 denotes a light guide, 21a denotes an inclined end face of the light guide, 21a1, 21a2 denotes first and second inclined end faces forming end faces, 22 a light source, 22a a center of a light source, 23 ... reflecting mirror, 24: light guide plate, 24a: light guide plane (display surface), 24b: light guide plane, 25: light diffuse reflection layer, θ: acute angle, A: perpendicular (normal line) .

Claims (6)

[Claims] 1. A surface light emitting device that emits light from a light source provided opposite to an end face of a planar light emitting body having a flat shape from the end face to emit a light emitting surface of the light guide. 3. The surface light emitting device according to claim 1, wherein the end surface of the light guide is an inclined surface, and the light source is disposed on a perpendicular line to the end surface. 2. An acute angle θ formed between one surface of the light guide, at which light passing through the inclined end face is reflected first and the inclined end face, is defined as θ> sin ⁻¹ n0 / n1 (where n0 The surface light emitting device according to claim 1, wherein n is a refractive index in air, and n1 is a refractive index of the light guide. 3. The light guide is provided with a light diffusion / reflection layer for diffusing and reflecting light incident on this plane on a plane opposite to the light emitting surface, and the concentration of the light diffusion / reflection layer is inclined. The surface light emitting device according to claim 1, wherein the surface light emitting device is continuously thinned as approaching an end face. 4. The surface emitting device according to claim 3, wherein the acute angle is located on the side of the light diffusion reflection layer. 5. An end face of the light guide is formed by first and second inclined end faces which are inclined in opposite directions with respect to a center position in a thickness direction of the light guide, and both inclined end faces are formed. The surface light emitting device according to any one of claims 1 to 3, wherein the light sources are arranged so as to individually face each of the units. 6. A light source according to claim 1, wherein a reflector for accommodating said light source is disposed so as to face said inclined end face, and a focal point of said reflector and a center of said light source are matched. 6. The surface emitting device according to claim 5.