JP2605298Y2 - 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 surface light source device used for a liquid crystal backlight, a lighting display, a lighting sign, a lighting body and the like.

[0002]

2. Description of the Related Art FIG . 2 is a cross-sectional view showing an example of a conventional surface light source device. 4 is the emission surface 3
A diffuser 5 is provided on the outer surface of the light guide 2 for diffusing light in each direction. Reference numeral 5 denotes a reflection member disposed on the side of the light guide 2 facing the light exit surface 3, and reference numeral 6 denotes a housing of the surface light source device.

The light emitted from the light source 1 is incident on the light guide 2 and is transmitted directly or while the reflection member 5
Then, the light is transmitted through the diffuser 4 from the light exit surface 3 and is diffused and emitted.

FIG . 3 shows an example of a surface light source device having another configuration, in which two linear light sources 1 are arranged in parallel on a reflecting member 5 and a diffuser is provided on the light source 1 with an appropriate interval. 4 and the light emitted from the light source 1 is partially part of the direct diffuser 4.
, The other light is reflected by the reflection member 5 and travels toward the diffuser 4, and is transmitted through the diffuser 4 and emitted in a diffused state.

The diffuser 4 used in FIGS. 2 and 3 is a transparent sheet or a plate in which a diffuser 4b is uniformly applied. Even when the surface light source has an appropriate luminance distribution, the light passing through the diffuser 4 is attenuated by the diffusing agent 4b, and the luminance of the surface light source device may be greatly reduced.

[0006] FIG. 4 does not cover the diffuser 4 on the outer surface of the light exit surface 3 of the light guide 2 as in the surface light source device shown in FIG.
An ink containing a foaming agent is directly printed and attached by screen printing to a surface 3 ′ of the light guide 2 facing the emission surface 3,
Next, the ink 7 is foamed by heating and finally dried by heating at a low temperature.
The light guide 2 is provided with irregular reflection portions 8 of the ink 7 in which the large and small hollow particles 4c are randomly distributed throughout the inside of the light guide 2 by drying and curing.

In this case, the light directed to the surface 3 ′ of the light guide 2 facing the emission surface 3 is diffused and diffused by the irregular reflection portion 8 and emitted from the emission surface 3.
The unevenness in brightness is reduced by variously changing the printing pattern, but since only light directed to the surface 3 ′ of the light guide 2 facing the emission surface 3 is diffused, the diffusion effect is small, and It is necessary to separately arrange the diffuser 4 on the side of the surface 3, which makes the production difficult and increases the cost.

[0008]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention provides a diffuser for a surface light source device that can make the luminance distribution uniform and obtain high luminance even if there is a difference in the distribution of the amount of emitted light. The purpose is to provide.

[0009]

SUMMARY OF THE INVENTION A surface light source device according to the present invention is provided with a light source which has been subjected to a process for reducing luminance unevenness on an emission surface.
Light source and the guide to allow for a more uniform brightness distribution.
A surface light source device having a diffuser used together with an optical body.
Therefore, the diffuser is formed by coating a diffusing agent in which fine particles having a low light attenuation rate are mixed therein on one surface or both surfaces of the transparent substrate , and an emission surface portion where the amount of emitted light is small. The distribution of the fine particles
The diffusing agent is characterized in that the portion disposed on the exit surface portion where the amount of emitted light is large so as to increase the degree of emission is coated with the diffusing agent so that the distribution density of the fine particles is reduced .

[0010]

According to the present invention, the diameter of the fine particles made of glass beads or hollow particles is changed depending on the part, or the density is changed depending on the part. Since the body works, a uniform luminance distribution due to light diffusion can be obtained. Also book
Diffusers in the invention are glass beads and hollow particles.
Diffusion mixed with fine particles with low light attenuation
Since it is formed by coating with an agent, a light decay rate is smaller than that of a conventional diffuser , and it is possible to realize a surface light source device having higher luminance than the conventional diffuser.

[0011]

FIG. 1 is an enlarged vertical sectional view of a diffuser according to the present invention. In the figure, 4a is a transparent sheet or plate, 4b
Is a diffusing agent coated on one surface of a transparent sheet or plate 4a, and 4c is a light composed of glass beads or hollow particles having a diameter of 10 μm or less distributed at substantially the same density throughout the diffusing agent 4b. These particles have a low attenuation rate .

The reason why the diameter of the fine particles 4c is set to 10 μm or less is that the experiment was conducted by mixing fine particles 4c made of glass beads or hollow particles of various diameters into the diffusing agent 4b. In this case, it has been found that the effect of increasing the brightness is reduced.

[0013] The diffuser 4 in FIG. 1, the distribution of the fine particles 4c
Density is low at the exit surface area where the surface light source device emits a large amount of light.
In the area of the emission surface where the amount of light emitted from the surface light source device is small,
So as placed to make to. Experiments have shown that this arrangement makes it possible to make the luminance distribution on the diffuser 4 uniform.

In the embodiment shown in FIG . 1, the transparent substrate 4a is
Both surfaces are coated with a diffusing agent 4b mixed with the fine particles 4c.
Diffuser 4 is formed on the surface of one side of the transparent substrate.
A diffusion material coated with a diffusing agent 4b mixed with the fine particles 4c;
4, the same effect as in FIG. 1 can be obtained.

The fine particles 4c are mixed on one surface of the transparent substrate.
When the diffuser 4 is formed by coating the
In this case, even if the surface on the side coated with the diffusing agent 4b is arranged so as to face the emission surface 3 of the light guide 2, or vice versa,
The same effect was obtained by arranging the surface not coated with the diffusing agent 4b so as to face the emission surface 3 of the light guide 2.

Further , according to the present invention , the brightness unevenness on the exit surface is reduced.
A light guide that has been treated for reduction is used.
The processing may include, for example, forming a concave
There is a method to reduce uneven brightness by forming a convex pattern.
You.

Since the surface light source device according to the present invention is configured as described above, the desired light diffusion efficiency can be easily obtained for each part, and the luminance unevenness can be reduced as much as possible. I can do it.

[0018]

According to the present invention, as described above, a diffuser having a different light diffusion efficiency is applied in accordance with a difference in the amount of emitted light, so that a uniform brightness distribution can be obtained by light diffusion. Can be. In addition, a method for reducing uneven brightness by forming a concavo-convex pattern on the surface facing the light-emitting surface of the light guide can be implemented together, so that the object can be effectively achieved and the conventional surface light source device can be modified. The present invention can be adopted without using the present invention.

[Brief description of the drawings]

FIG. 1 is an enlarged vertical sectional view of a diffuser used in a surface light source device according to the present invention.

FIG. 2 is a longitudinal sectional view of a conventional surface light source device.

FIG. 3 is an enlarged vertical sectional view of another conventional surface light source device.

FIG. 4 is an enlarged longitudinal sectional view of still another conventional diffuser.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light source 2 Light guide 3 Emission surface 4 Diffuser 4a Transparent sheet or board 4b Diffusing agent 4c Fine particles made of glass beads or hollow particles 5 Reflecting member 7 Ink 8 Diffuse reflection part

Claims (2)

(57) [Scope of request for utility model registration] 1. A process for reducing luminance unevenness on an output surface is described.
Light and body has been subjected to a surface light source device having a more uniform luminance distribution used with the light guide to enable diffuser, said diffuser, one surface of the transparent substrate Alternatively, both surfaces are coated with a diffusing agent in which fine particles having a low light attenuation rate are mixed therein to form the fine particles.
The distribution density of the fine particles is low in the portion arranged at the exit surface portion where the amount of emitted light is large so that the distribution density of the particles is high.
The surface light source device , wherein the diffusing agent is coated as described above. 2. The surface light source device according to claim 1, wherein the diameter of the fine particles is 10 μm or less.