JPH11191307A - Surface light emitting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface light source unit of a photoconductor system capable of achieving a uniform surface light source with a point-source light. SOLUTION: A side face light emitting portion of a rod-like first photoconductor 2 having a point-source light emitter disposed at the tip thereof is connected to one side end of a plate-like second photoconductor 5, thereby providing a surface light emitting apparatus which obtains a radiation beam from a main surface of the second photoconductor 5. Consequently, light emitted from a point-source light 1 is converted into light of a linear light source by means of the first photoconductor 2, and further, is converted into light of a uniform surface-like light source by means of the second photoconductor 5, thus obtaining a uniform surface-like light source.

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 as a planar light source, and more particularly, to a light guide structure for converting a point light source into a surface light source.

[0002]

2. Description of the Related Art A planar light source capable of obtaining uniform brightness over a wide area is required for, for example, a liquid crystal backlight. The light source is a fluorescent lamp, a cathode ray tube, or the like. Etc. have been used.

Recently, light-emitting diodes (hereinafter, referred to as LEDs) have been attracting attention as point light sources because of their small size and low power consumption. However, they are scattered over a wide area to ensure uniformity throughout. It has been quite difficult to achieve both high efficiency and high use efficiency of light from a light source.

[0004] A conventional surface light source device using an LED, as shown in an external perspective view of FIG.
The ED 11 is juxtaposed on one side surface of the flat light guide 12 at a predetermined interval, and a reflection plate is provided on the rear surface and the other side surface of the flat light guide 12 so that light is not emitted from other than the main surface of the flat light guide 12. 13 and a diffusion plate 14 for obtaining uniform brightness from the main surface.

Light emitted from the LED 11 enters the light guide 12 and is uniformly diffused by the diffusion plate 14 provided on the light emission surface side while being repeatedly reflected by the reflection plate 13 to irradiate necessary portions.

[0006]

However, in the above-described conventional configuration, the brightness is high in the vicinity of each LED, and
There was a problem that the gaps without the holes were dark. In order to obtain a uniform portion, as shown in the external perspective view of FIG. 7, a light-shielding plate 15 is provided on one side surface so that a bright portion near the side surface where the LEDs are arranged is not used. Although not shown, a diffuser plate having a thicker side surface may be provided. However, in any case, the scattered light to a part other than the main surface of the flat light guide 12 used as the light emitting surface increases, and the use efficiency of the radiated light from the light source is inevitably reduced.

An object of the present invention is to provide a light guide type surface light source device capable of realizing a uniform surface light source using a point light source.

[0008]

According to the present invention, there is provided a first light guide for temporarily converting a point light source into a linear light source, and a first light guide for converting the linear light source into a planar light source. 2 light guides, whereby a bright and uniform small surface light source can be realized with a point light source.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a light emitting portion on a side surface of a rod-shaped first light guide having a light emitting member provided at a tip portion is provided at one end of a plate-shaped second light guide. A surface light emitting device configured to obtain light emitted from the main surface of the second light guide by coupling.

According to such a surface light emitting device, the light emitted from the point light source is converted into the light of the linear light source by the first light guide, and further, the light is emitted from the uniform light by the second light guide. By converting the light into the light from the light source body, a uniform planar light source is realized.

In the surface light emitting device of the present invention, the first and second light guides are formed of the same material and are coupled to each other so that light emitted from the point light source can be transmitted to each of the first and second light guides. The light can be converted into light from a planar light source without loss such as reflection at the coupling interface of the light guide.

Further, the surface light emitting device of the present invention is characterized in that:
In the configuration in which an adhesive made of a light-guiding material is provided at a joint between the light-guiding member and the second light-guiding member, light linearized by the first light-guiding member is emitted. The light can be guided to the second light guide without loss such as reflection, and can be used as a light source for obtaining uniform planar radiation.

Still further, in the surface light emitting device according to the present invention, the adhesive provided at the joint between the first light guide and the second light guide may have the same refractive index as each of the light guides. By using the above materials, there is a remarkable effect in that the light emitted from the point light source is converted into the light of the planar light source without loss such as reflection at the coupling interface between the light guides.

[0014]

The embodiments of the present invention will be described below in more detail with reference to examples.

FIG. 1 is an external perspective view of a surface light emitting device according to an embodiment of the present invention, and FIG. 2 is a side view thereof.

In FIGS. 1 and 2, the device is an LED.
Is disposed at one end of a rod-shaped first light guide 2 for converting a point light source 1 into a linear shape, and a catadioptric unit 3 is attached to one side surface of the first light guide 2 in the longitudinal direction. The other side facing this is combined with one side end of a plate-shaped second light guide 5 that converts light into a plane at the connection portion 4. This connection part 4 is the first
It is preferable to use materials having the same refractive index in order to optically couple the light guide 2 and the second light guide 5 with each other and eliminate light loss at the joint interface. In addition, a catadioptric portion 6 is provided on the back surface of the second light guide 5.

1 and 2, light emitted from a point light source 1 installed at an end of a first light guide 2 repeats refraction and reflection in the first light guide 2 to form a line. The first light guide 2 is reflected and refracted by the catadioptric portion 3 provided on the side surface of the first light guide 2, and is guided to the second light guide 5 through the connection portion 4. In the second light guide 5, the linear light incident through the connecting portion 4 is spread in a planar shape while repeating the reflection and refraction, and the catadioptric portion 6 provided on the back surface of the second light guide 5 causes The light is emitted from the main surface of the plate-like second light guide 5 as uniform planar radiation.

In this embodiment, the point light source 1 is
Although an example of the case where a plurality of light sources are installed is shown, it is needless to say that the number of the point light sources 1 can be one, or a large number of four or more light sources, and furthermore, a single color or a multicolor mixed mounting is possible. .

As shown in the schematic explanatory view of FIG. 3, the first light guide 2 is formed of a transparent or translucent material such as resin (for example, acryl) or glass, and is provided at an end. In order to efficiently transmit and transmit the light from the point light source 1 and emit the transmitted light from one side in the longitudinal direction, the side opposite to the output side is reflected or refracted. The catadioptric portion 3 made of a material is installed by a processing technique such as pasting, painting, or vapor deposition. Specifically, a metal or a white material for reflection is applied, or a surface roughening process for light scattering, a chevron shape for refraction, and a spherical surface process are performed.

FIGS. 1, 2 and 3 show an example in which the first light guide 2 has a rod shape or a column shape. In addition to these cylinder shapes, the vertical cross section has a polygonal shape, an elliptical shape, a parabolic shape or the like. Rod-shaped body, furthermore, one that is thicker at one point light source side in the longitudinal direction and thinner and inclined at the other end, that is, each cross section perpendicular to the longitudinal direction is gradually reduced. However, it can be configured.

FIGS. 1, 2 and 3 show a case where the point light source 1 is installed at one end of the first light guide 2.
It is also possible to adopt a configuration in which the point light sources 1 are installed at both ends.

Further, FIGS. 1, 2 and 3 show a case where the linear light source composed of the first light guide 2 is installed alone at one end of the second light guide 5. It is also possible to install two individually at both end portions of the second light guide 5, or to install four in each of the four surroundings of the second light guide 5 to make four.

As the second light guide 5, a light guide having an uneven surface on which a number of polygonal projections are provided can be used.

The second light guide 5 is made of a transparent material such as resin or glass, like the first light guide 2.

Note that the second light guide 5 is a first light guide 2
In order to efficiently transmit and transmit the linearly emitted light incident from the connection portion 4 with the connecting portion 4 and emit the transmitted light from the main surface,
That is, it is preferable to provide the catadioptric portion 6 on the surface opposite to the exit surface side.

In each of the drawings shown in the embodiments, the second light guide 5
Is simplified and the planar shape is shown as a rectangle, but a polygonal shape, a circular shape, or the like can be used.

The second light guide 5 is not limited to a plate-like body having a rectangular cross section as shown in FIGS.
As shown in the side view in FIG. 4, the side surface is tapered to gradually reduce from the line light source side end to the other end side. Further, as shown in the side view in FIG. 5, the side opposite to the emission surface side A curved surface can be used.

It is effective to provide a catadioptric section 6 for efficiently transmitting and emitting light also on the back surface of the second light guide 5. As in the case of the formation of the catadioptric portion 3 installed in 2, the metal or white material is applied, stuck and installed, or a surface roughening process for light scattering, a chevron process for refraction, a spherical process, etc. Can be formed.

[0029]

As described above, according to the present invention, the light of a point light source is efficiently converted into uniform planar radiation light by each of rod-shaped and plate-shaped light guides. The surface light-emitting device of the present invention is suitable for a liquid crystal backlight as a small and simple surface light source.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a surface emitting device according to an embodiment of the present invention.

FIG. 2 is a side view of the surface emitting device according to one embodiment of the present invention.

FIG. 3 is a schematic explanatory view of a first light guide according to one embodiment of the present invention.

FIG. 4 is a side view of a surface emitting device according to another embodiment of the present invention.

FIG. 5 is a side view of a surface emitting device according to another embodiment of the present invention.

FIG. 6 is an external perspective view of a conventional surface emitting device.

FIG. 7 is an external perspective view of another conventional surface light emitting device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 point light source 2 first light guide 3 catadioptric unit 4 connection unit 5 second light guide 6 catadioptric unit

Claims (4)

[Claims] 1. A light emitting portion on a side surface of a rod-shaped first light guide having a light-emitting member provided at a distal end thereof is connected to one side of a plate-shaped second light guide, and the second light guide is connected to the second light guide. A surface emitting device that obtains radiated light from the main surface of a light guide. 2. The surface light emitting device according to claim 1, wherein said first and second light guides are formed of the same material. 3. An adhesive made of a light-guiding material is provided at a joint between the first light-guiding member and the second light-guiding member.
Or the surface emitting device according to 2. 4. The surface emitting device according to claim 3, wherein the adhesive is made of a material having the same refractive index as the first and second light guides.