JPH01154086A - Light source panel - Google Patents

Abstract

PURPOSE: To obtain high luminance and improve the performance of the surface light source device by arranging a reflection body which has a silver reflecting film nearby each projection end surface. CONSTITUTION: A light diffuser 1 is formed by laminating light-transmissive plate bodies 10, putting their one-end sides in order into an incidence end surface 1A, and arranging the other-end sides in a staircase stepped shape toward the back surface to form a projection end surface 1B. This light diffuser 1 guides light which is made incident on the incidence surface 1A and projects it from the projection end surface 1B, and the reflection body 4 which has the silver reflecting surface is arranged nearby the projection end surface 1B. Therefore, the light is efficiently reflected by this surface, refracted while made incident on the light-transmissive plate bodies 10 again, and transmitted through a diffusion plate 3 and projection. Consequently, the light whic is transmitted through the diffusion plate 3 is sufficiently diffused to have a uniform illumination plane.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a surface light source device used as a surface light source for signboards, various display devices, and the like.

(Prior Art) Large-sized surface light source devices are used as signboards and display devices, and small-sized surface light source devices are used in various instruments and liquid crystal display devices. Conventional devices of this type often have a light source such as a fluorescent lamp installed on the back of the display board, but in order to make the brightness of the display board uniform, it is necessary to use multiple light sources and place them on the back. Or the light source had to be placed far enough away from the back of the display board. However, increasing the number of light sources as in the former case not only increases the initial cost, but also has the drawbacks of high power consumption and heat generation. Furthermore, when the light source is placed away from the back of the display panel as in the latter case, the depth of the housing becomes large and there is a drawback that the device cannot be made thinner.

(Problems to be Solved by the Invention) In view of this situation, a surface light source device in which a linear light source is arranged at one end of a plate-shaped light guide has already been proposed. Although this device can satisfy the requirements for a thinner device, it is difficult to make the brightness of the illumination surface uniform. To solve this problem, the present applicant stacked a large number of light-transmitting plate-like bodies, aligned the minus side edges of each body to form a light incident end face, and formed a step-like step with the other side edges facing the back side. proposed a light diffuser whose output end face is arranged so as to produce
0-87387). When this light diffuser is used as a surface light source, a reflective surface is provided on the output end face, but in the present invention, we investigated how to further increase the reflection efficiency of this reflective surface and improve the brightness. It has also been found that the reflection efficiency increases when a silver reflective surface is used for this purpose, leading to the present invention.

(Means for Solving the Problems) That is, the gist of the present invention is to provide a surface light source device comprising a light source disposed at at least one side end of a light diffuser and a diffuser plate provided in front of the light diffuser. The light incident end face is formed by aligning one end of each of a plurality of laminated translucent plates, and the other end faces toward the back side, creating a step-like step. The surface light source device is characterized in that the light emitting end faces are arranged in a plurality of planes, and a reflector having a silver reflective surface is disposed near each of the light emitting end faces.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 and 2.

In the figure, (1) is a light diffuser, (2) is a light source, (3) is a diffuser plate, (4) is a light reflector, and (5) is a housing.

Of these, the light diffuser (1) includes a plurality of transparent plate-like bodies (1
0) are stacked, and the - side ends of each are aligned to form an incident end face (1A), and the other ends of each are arranged to face the back side to form a step-like step to form an output end face. (1B) is formed. As the light-transmitting plate-like body (10) constituting the light diffuser (1), a synthetic resin plate such as acrylic resin, polycarbonate resin, or vinyl chloride resin is used, but is not limited thereto.

The light diffuser (1) guides the light incident from the input end face (1A) and outputs it from the output end face (1B), but near the output end face (1B) there is a reflector (1) having a silver reflective surface. 4), the light is efficiently reflected from this surface, refracted while entering the light-transmitting plate (10), and transmitted through the diffuser plate (31) to be emitted.

As a result, the light passing through the diffuser plate (3) is sufficiently diffused,
A uniform illumination surface can be achieved.

In particular, in the present invention, since the reflector (4) having a silver reflective surface is used, the reflection characteristics are excellent, and Table 1 shows these values.

Table 1 In the illustrated example, the reflector (4) is extended and the light source (2)
), which increases layer efficiency, but this reflector portion may of course be a separate piece or may be omitted.

A more detailed example will be described below.

(Specific example) An acrylic resin plate with a thickness of 1 mm was used as a translucent plate, and this resin plate was cut into a width of 194 m (Fig. 2 W), and the length was cut from 57 m to 5 m with a pitch ( Figure 2 P)
Nine pieces were cut so that the length was &5m. Then, the end faces of these resin plates were polished and stacked, and adhesive was applied to both sides to produce a light diffuser.

An 8W fluorescent tube was installed at the incident end of the light diffuser, and a reflector made of a 100μ thick polyester film coated with silver via an undercoat was used to double as a reflector. While covering the fluorescent tube, an acrylic resin diffusion plate was installed near the output end face (see Figure 1), and an acrylic resin diffusion plate was installed in front.

The thus manufactured surface light source device was turned on using a 24 V input inverter, and the brightness on the diffuser plate was measured in 9 width sections and 6 length sections.

The brightness was measured using a Minolta NP-173° brightness meter with a spot diameter of 10 squares.

This result is shown in Figure 3, where the numerical value of each section is the luminance (c
d/m''), which was approximately s,oO0 or higher, and there were few spots.

(Comparative example) A surface light source device using exactly the same light diffuser, light source, and diffusion plate as in the above specific example, and using an aluminum-deposited polyester film (thickness 100μ) as a reflector, and installing it in the same manner as in the specific example. was produced.

This surface light source device was turned on in the same manner as in the specific example, and the brightness on the diffuser plate was measured. Figure 4 shows this result.
Compared to the specific example of the present invention, the brightness value is small and there are some spots.
On the contrary, it was confirmed that the average luminance value of the specific example of the present invention was about 1.6 times higher.

Furthermore, when the reflector used as a specific example of the present invention was treated in an environment of high temperature and high humidity, it was confirmed that there was no change even over a long period of time, and there was no problem in practical use.

(Effects of the Invention) Since the present invention has the configuration as described in detail above, by using a reflector having a silver reflective film, unexpectedly higher brightness can be obtained compared to the conventional one, and it can be used as a surface light source. This has the advantage that the performance of the device can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a surface light source device showing an embodiment of the present invention;
FIG. 2 is a perspective view of a light diffuser used in this, FIG. 3 is an explanatory diagram showing brightness values in a specific example of the present invention, and FIG. 4 is an explanatory diagram showing brightness values in a comparative example. (1)...Light diffuser (10)...Translucent plate-like body, (1A)...Incidence end face, (1B)...Output end face (2)...Light Source (3)・・・Diffusion plate package）・・・Reflector Patent applicant Mitsubishi Rayon Co., Ltd. Agent Patent attorney Satoshi Yoshizawa Fusen 1 illustration 2 concave

Claims (2)

[Claims] (1) In a surface light source device comprising a light source disposed on at least one side end of a light diffuser and a diffuser plate on the front side, the light diffuser is arranged on one side of each of a plurality of laminated translucent plate bodies. The ends are aligned to form a light input end face, and the other ends face toward the back side to form a step-like step to form an output end face. A surface light source device characterized in that a reflector having a silver reflective surface is arranged. (2) A light diffusing device as set forth in claim 1, characterized in that the reflector extends to cover the outside of the light source.