JPH03111819A - Optical waveguide plate device - Google Patents

Abstract

PURPOSE:To improve the efficiency of light emission and to increase the light emission brightness of the side of a light emission surface sufficiently by frosting the light emission surface of an optical waveguide plate which is slanted down decreasing in thickness gradually from both end surfaces to the center part. CONSTITUTION:The optical waveguide plate 15 has the light emission surface 16 as one surface and a light shield surface 17 as the other surface and the light emission surface 16 is slanted down from both the end surfaces 18 of the optical waveguide plate 15 to the center part and frosted. Light from a light source 24 is made incident on the optical waveguide plate 15 from both the end surfaces 18 of the optical waveguide plate 15, part of the light reaches the light emission surface 16 directly without being reflected by the light shield surface 17, and the rest is reflected by the light shield surface 17 to reach the light emission surface 16, where the light is emitted out of the optical waveguide plate 16 from the light emission surface 16 while irregularly refracted. The light emitted from the light emission surface 16 passes through two light diffusion member 23 and is emitted out and diffused, so the light of the light source 24 is emitted uniformly from the entire light diffusion surface 16, so the light emission brightness is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a light guide plate device used as a backlight for a liquid crystal color television, a computer, a computer, a backlight for a signboard, or a lighting fixture.

<Prior Art> Fig. 10 shows a conventional light guide plate device, in which 1 is a light guide plate, which is made by superposing two acrylic plates 2 each having a thickness of 411II11 and an acrylic plate 3 having a thickness of 201111mm. One surface of 1 is a light-diffusing surface 4, and the other surface is a light-shielding surface 5.

A light diffusing member 6 made of, for example, a polycarbonate film is attached to the light-diffusing surface 4, and a white polyethylene sheet 7 is attached to the light-shielding surface 5 to prevent light leakage. By performing this processing, spots 9 are provided in a scattered manner to diffusely reflect light. Then, a light source 10 such as a lamp is provided at both ends of the light guide plate 1, and a cover 11 made of a vinyl chloride film with a H2 of about 0.5 rsm is provided, so that the light source 10 is emitted from the side end surface of the light guide plate 1. enters the light guide plate 1, the incident light is repeatedly reflected between the light shielding surface 5 and the light diffusing surface 4, and is diffusely reflected by the spots 5, and the diffusely reflected light is emitted from the light diffusing surface 4 to produce light. The radiation surface 4 side was made to emit light.

<Problem to be solved by the invention> However, in the conventional case, due to reasons such as repeated reflection of light between the light-diffusing surface 4 and the light-shielding surface 5, the light emitted by the light guide plate device is not enough to emit light from the surface. The loss is large and the luminance of the light emitted from the light-diffusing surface 4 side does not increase very much. Therefore, it cannot be used for color liquid crystals that require a high-brightness backlight.

In view of the above-mentioned problems, the present invention is designed to improve the efficiency of light emission and sufficiently increase the brightness of light emission on the light-diffusing surface side.

Means for Solving the Problem> The technical means of the present invention for solving this technical problem includes a light guide plate 15 having one side as a light-diffusing surface 16 and the other side as a light-shielding surface 17, The light is transmitted to both end surfaces 1 of the light guide plate 15.
In the light guide plate device, the light guide plate 15 is gradually thinned from the both side end faces 18 toward the center. The light-diffusing surface 1 of the light guide plate 15 is
6 is inclined downward from both ends toward the center, and the light guide plate 15
The light-diffusing surface 16 of the light-diffusing surface 16 has a matte finish.

Function> As shown in FIG. 7, the light from the light source 24 enters the light guide plate 15 from both end surfaces 18 of the light guide plate 15, and a part of this light is not reflected by the light shielding surface 17 but directly passes through the light diffusing surface. 16, and the other part reaches the light-diffusing surface 16 after being reflected by the light-shielding surface 17, where it is diffusely refracted and emitted from the light-diffusing surface 16 to the outside of the light guide plate 15. The light is emitted to the outside through the two light diffusing members 23, and during this time, the light emitted from the light guide plate 15 is diffused by the light diffusing member 23, so that the light diffusing surface 16 side of the light guide plate 15 is completely covered. Emit light approximately evenly.

Note that if the arcuate portion 16a is not provided at the center of the light-diffusing surface 16 and this portion is bent into a 7-shape, the light-diffusing surface 16 side of the light guide plate 15 will be bent in correspondence with this bent portion. Although a dark line appears at the center, in the embodiment, an arcuate portion 1 is formed at the center of the light-diffusing surface 16.
6a, it is possible to effectively prevent the occurrence of dark lines as described above due to the arc portion 16a.

<Example> Hereinafter, the present invention will be explained according to the illustrated example.
In the drawings to FIG. 3, reference numeral 15 denotes a light guide plate made of a transparent acrylic plate, with one side serving as a light-diffusing surface 16 and the other side serving as a light-shielding surface 17. As shown in FIGS. 4 to 6, this light guide plate 15 is formed so that it becomes gradually thinner from both side end surfaces 18 toward the center, and the wall thickness at both side ends is about 12 m+s, and the wall thickness at the center is about 12 m+s. is approximately lrm, and the light-diffusing surface 16 of the light guide plate 15 is inclined downward from both ends toward the center, and an arcuate portion 16a is provided at the center of the light-diffusing surface 16.

The light-diffusing surface 16 of the light guide plate 15 is subjected to a matte finish such as matte finish or puff finish, and both side end faces 18 are finished with a glossy puff finish.

Reference numeral 21 denotes a light shielding member, which is made by pasting a silver vapor-deposited film with a thickness of about 0.1 mm on the inner surface of a polyethylene film with a thickness of about 0.25 mm. It is attached to 22.

Reference numeral 23 denotes a light diffusion member, which is made of a polycarbonate film that diffuses light, and two sheets are arranged on the light diffusion surface 16 side so as to cover the light diffusion surface 16 of the light guide plate 15.
The surface of No. 3 is formed into a rough surface so that light can be more strongly diffused.

Reference numeral 24 denotes a light source, which is composed of a cold cathode tube lamp, and two of which are arranged outside the end surfaces 18 on both sides of the light guide plate 15.
The light enters into the light guide plate 15 from both end surfaces 18 of the light guide plate 15. Reference numeral 25 denotes a light-shielding cover, which is made by pasting a silver vapor-deposited film with a thickness of about 0.1 wm on the inner surface of a vinyl chloride film.The light-shielding cover 25 is made by pasting a silver vapor-deposited film with a thickness of about 0.1 wm on the inner surface of a vinyl chloride film. It covers the outer periphery of 24.

Next, the embodiment of the present invention shown in FIGS. 1 to 3 and the 1θ
The results of comparison with the conventional example shown in the figure will be explained.

Note that the light guide plate devices of the present invention and the conventional example have a total thickness of
Those having the same size, number of light sources 24, and light intensity are compared. FIG. 8 shows the brightness measured at nine points on the effective light emitting surface of the light guide plate device in the embodiment of the present invention, and FIG. 9 shows the brightness measured at nine similar points in the conventional example. ing. As shown in FIGS. 8 and 9, the embodiment of the present invention has higher brightness over the entire light emitting surface than the conventional example, and in the case of the present invention, the brightness is higher over the entire light emitting surface. The average luminance value of 4150cd/mz
In contrast, in the case of the conventional example, the average brightness is 2800 cd.
It was 7m2. Regarding weight, in the case of the present invention, the weight of the entire device is 400g, while in the case of the conventional example, the weight is 700g, and the brightness of the example of the present invention is 148% higher than that of the conventional device. Moreover, the weight has been reduced by 57%.

<Effects of the Invention> According to the present invention, the light diffusing surfaces 16 of the light guide plate 15 descend from both side ends toward the center so that the light guide plate 15 gradually becomes thinner from the both side end surfaces 18 toward the center. Since the light diffusing surface 16 of the light guide plate 15 is tilted and has a matte finish, the light source 24 incident on the light guide plate 15 from both end surfaces 18
The light reaches the light diffusing surface 16 directly or after being reflected by the light shielding surface 17, approximately evenly over the entire light diffusing surface 16, and without repeating reflection many times within the light guide plate 15. The light is diffusely refracted by the diffusing surface 16 and emitted to the outside. Therefore, the light from the light source 24 can be uniformly and efficiently emitted from the entire light-diffusing surface 16, and the luminance on the light-diffusing surface 16 side can be significantly increased. It can also be used for many purposes, and its practical effects are significant.

[Brief explanation of drawings]

1 to 7 show an embodiment of the present invention, in which FIG. 1 is a front view, FIG. 2 is a side sectional view, FIG. 3 is a bottom view, and FIG. 4 is a front view of the light guide plate. 5 is a side view of the same, FIG. 6 is a bottom view of the same, and FIG. 7 is a sectional view for explaining the operation. Figures 8 and 9
The figure is a front view showing the results of brightness measurements of the present invention and a conventional device. FIG. 10 is a sectional view showing a conventional example. DESCRIPTION OF SYMBOLS 15... Light guide plate, 16... Light-diffusion surface, 17... Light shielding surface, 18... Side end surface, 24... Light source.

Claims (1)

[Claims] (1) One side is a light-diffusing surface (16) and the other side is a light-shielding surface (16).
7), the light from the light source (24) enters from both end surfaces (18) of the light guide plate (15) and is diffused from the light diffusion surface (16) of the light guide plate (15). In the light guide plate device, the light guide plate (15) is arranged such that the light guide plate (15) gradually becomes thinner from the both end surfaces (18) toward the center. ) The light-diffusing surfaces (16) of the light-guiding plate (15) are sloped downward from both ends toward the center, and the light-diffusing surfaces (16) of the light-guiding plate (15) are subjected to a matte finish.