JPS61171001A - Diffuser for lighting - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a light diffusing device used for back illumination of light receiving cells such as liquid crystal cells and electrochromic cells.

[Prior art]

Conventionally, back illumination of liquid crystal cells and the like has been carried out by reflecting the illumination light using a diffuse reflector plate 41'' to make the illumination light as uniform as possible. Therefore, there was a drawback that the volume of the back surface of the liquid crystal cell had to be increased. or,
The purpose is achieved by making the shape of the acrylic plate used as the reflecting plate complex so that the reflected light is uniform. Therefore, although the liquid crystal cell itself is thin, the display device as a whole becomes thick, which is undesirable.

[Purpose of the invention]

The present invention has been made in order to eliminate the above-mentioned drawbacks, and an object thereof is to provide a thin flat diffuser having approximately the same area as the surface of an object to be illuminated such as a liquid crystal cell. be.

[Structure of the invention]

The illumination diffuser of the present invention includes a thin flat core made of a transparent material with a high refractive index, and a material with a lower refractive index than the core provided on the upper and lower wide surfaces of the core and the end portion excluding the pre-incident port. This cladding has a very large number of small holes in one planar part of the cladding, and even after illumination light enters from the light entrance and is repeatedly reflected by the interface between the core and the cladding. Uniform white illumination light is obtained by emitting light from a small hole.

〔Example〕

FIG. 1 is a diagram showing an embodiment of the illumination light generating device of the present invention, in which 1 is an extremely thin flat core made of a transparent material with a refractive index of NL, and 2 is an illumination light entrance. part 1
A cladding made of a thin film-like substance with a refractive index of n2 is provided on both the upper and lower planes of the core 1 and each end face, except for a, and 3 is an extremely large number of small holes formed on one surface of the cladding 2. Also shown in FIG. 2 is an illumination light generating device, which consists of a light source 4 such as a cold cathode or hot cathode tube, a reflector 5, etc. The light from the light source 4 is reflected by the reflector 5 and then emitted from an exit aperture 6. be ejected. Note that n1) and n2.

In the above-described device, if the illumination light from the illumination light generating device is made to enter the diffuser through the incident Dla, the light will be reflected many times within the core 1 at the interface between the core 1 and the cladding 2. Of the light that is repeatedly reflected in this way, the light that reaches the small hole 3 exits the diffuser. In this case, since each light ray travels in a different direction and travels randomly, the illumination light is mixed by the repeated reflections and becomes uniformly diffused light. In this case, the valley wavelength lights are mixed to become white light.

If a diffusing agent is used on the back light source side of the cladding, T
The diffusion effect can be increased by mixing iO and ZnO. The diffusion effect can also be increased by making the surface on the back light source side with a score of 1 a complicated shape.

3 to 5 are diagrams showing various shapes of the core 1 provided with cladding 2, respectively. The one shown in FIG. 2, the upper surface is removed by polishing or the like to form a small hole 1a for light emission. In addition, in FIG. 4, the surface is cut into a pyramidal or conical shape, and after a cladding 2 is provided in the same manner, the upper surface is shaved to form a small hole 1a for light emission. Further, in FIG. 5, a large number of small lenses are formed on the upper surface, and after a cladding is provided, small holes 1a for light emission are provided by cutting. Therefore, the shapes of the small holes 1a are different from those in FIGS. 3 to 5. Furthermore, even in the case of a flat core with a cladding as shown in FIG. 1, the small holes may have any shape.

Note that a reflecting plate may be provided on the back light source surface and the cladding surface other than the incident side.

The above-described diffusion device can be formed by molding a portion of the core using acrylic resin or the like by injection molding or other molding methods, and then providing a cladding by coating or other means. Therefore, shapes such as those shown in FIGS. 3 to 5 can be easily formed. Alternatively, methods such as cast molding or two-color molding may be used, and thereby the core and cladding can be formed in one step.

〔Effect of the invention〕

The illumination device of the present invention is extremely thin (1 inch or less in thickness) and in the form of a flat plate, so that the entire display device can be made thin even when used for illuminating a liquid crystal cell or the like. Furthermore, since the illumination light is emitted after repeated reflections a very large number of times, the illumination light is white in color and has a uniform intensity distribution and is diffused. With such a structure, it is easy to increase the size. Further, as described above, after molding is performed using acrylic resin or the like as a material, a cladding can be provided on the surface by coating or other methods, or can be formed by a two-color molding method, etc., resulting in good productivity.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the diffusion device of the present invention, and FIG.
The figure is a perspective view showing an example of an illumination light generating device used with the diffusion device of the present invention, and FIGS. 3 to 5 are sectional views showing various examples of core shapes. 1... Core, 2... Clad, 3... Small hole for light emission

Claims (1)

[Claims] It consists of a core made of a thin flat plate-like transparent material, and a cladding formed on the surface of the core excluding the light entrance and formed with a number of light exits made of a material with a refractive index lower than that of the core, An illumination diffusion device in which light incident through an entrance is repeatedly reflected at the interface between a core and a cladding, and then exits from an exit.