JP3064006B2 - Surface emitting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a thin illumination light as a display, and a thin and lightweight laptop computer, word processor, and liquid crystal TV.
More specifically, the present invention relates to a so-called edge light type surface light emitting device.

2. Description of the Related Art Conventionally, various types of surface light emitting devices of this type are known. For example, there is a surface light source device in which a light guide plate is provided with irregular reflection portions that change the area ratio in an unrestricted manner (Japanese Patent Laid-Open No. 12650/1990).
1). In addition, there is a surface light emitting device in which a liquid crystal panel is arranged on the surface of a translucent plate, and a light scattering substance is directly applied to the back surface of the translucent plate, and then a specular reflector is installed. Kaihei 1-245220).

[Problems to be solved by the invention]

However, in the above structure, since the pattern density is high, defects such as ink fading are likely to occur during printing, and there are many variations in quality during mass production. Further, when the diffuse transmission portion is formed of a light diffusion material having a different refractive index from that of the transparent light guide plate, the efficiency of scattering and reflecting light is low, and the vicinity of the light source is too bright. In the case of the pattern shown in FIG. 2, a stripe called a density jump occurred at the boundary between the continuous portion and the non-continuous portion, causing uneven brightness and low brightness. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described problems and to provide a surface-emitting device that has high luminance, has no luminance unevenness, and has no variation in quality.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides a white light scattering / reflecting plate disposed on the back surface of a transparent light guide plate and a light source disposed on a side surface of the transparent light guide plate to irradiate the transparent light guide plate with light from the light source. In the surface light-emitting device, the transparent light guide plate and the white scattering reflector, between the light source so as to provide a diffuse transmission portion in a pattern of density 20 to 29 lines so that the area gradually increases as the area increases. Configured. Further, in the above configuration, the diffuse transmission portion may be formed of a light diffusion substance having a refractive index similar to that of the transparent light guide plate. Further, in the above configuration, the diffusion transmitting portions may be all island-independent patterns or all chain-connected patterns. Further, in the above configuration, a light diffusion layer can be arranged on the front side of the transparent light guide plate.

【Example】

Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. FIG. 1 is a sectional view showing one embodiment of the surface emitting device of the present invention. 3 to 5 are plan views showing one embodiment of the surface light emitting device of the present invention. 1 is a light source, 2 is a transparent light guide plate, 3
Is a light diffusion layer, 4 is a white scattering reflection plate, 5 is a diffusion transmission portion, 6
Indicates a curved reflecting plate. As shown in FIGS. 1 and 3 to 5, the surface light emitting device includes a white light scattering / reflecting plate 4 disposed on the back surface of a transparent light guide plate 2 and a light source 1 disposed on a side surface of the transparent light guide plate 2. In the surface light emitting device that irradiates the transparent light guide plate 2 with light from the light source 1, the area between the transparent light guide plate 2 and the white scattering reflector 4 is gradually increased as the distance from the light source 1 increases. The structure was such that the diffusion transmitting portions 5 were provided in a pattern having a density of 20 to 29 lines. As the transparent light guide plate 2, an acrylic resin plate, a polystyrene resin plate, a polycarbonate resin plate, a vinyl chloride resin plate, a methacrylic resin plate, or a glass having high transparency and good light transmittance is used. 2-30
mm is preferred. As an example, a transparent acrylic plate having a length of 240 mm, a width of 170 mm, and a thickness of 6 mm was used. The side surfaces of the transparent light guide plate 2 are preferably polished to a smooth surface, and the light sources 1 are arranged on both side surfaces of the transparent light guide plate 2 respectively. This light source 1 may be arranged only on one side surface of the transparent light guide plate 2. As the light source 1, a line light source such as a fluorescent lamp or a cold cathode tube is arranged, or a point light source such as a lamp or an LED is arranged. In the embodiment, a cold cathode tube having a tube length of 270 mm and a diameter of 6 mm was used as the light source 1. Further, it is preferable that a reflection curved plate 6 which is curved so as to cover the light source 1 is disposed, and the light from the light source 1 is reflected toward the transparent light guide plate 2 side by the mirror surface of the inner surface so that the light can be used effectively. . On the other hand, on the back surface of the transparent light guide plate 2, there is formed a diffusion / transmission portion 5 having a gradation such that the area gradually increases as the distance from the light source 1 increases. The light that has reached the diffuse transmission portion 5 from the light source 1 is diffused here, and travels in multiple directions such as a direction further away from the light source 1 of the transparent light guide plate 2. At this time, the diffusion transmitting portion 5 was formed with a density of less than 30 lines in order to improve the printing yield. However, when the density is less than 20 lines, the pattern of the diffusion transmission part 5 is visible from the surface of the surface light emitting device, so that 20 to 29 lines are preferable in surface light emission and printing yield. The line indicating this density is 1
It means the number of dots per inch. In addition, the diffusion transmitting portion 5 is made of an acrylic resin (a refractive index
1.49) a silica pigment with a refractive index similar to that of
41 to 1.49). Further, the diffusion transmitting portions 5 may be formed independently in an island shape as shown in FIG. 3 or may be formed in a chain shape as shown in FIG. As an example, a density of 28
The diffuse transmission part 5 was formed in a circular dot shape by a line. The diffuse transmission portion 5 is formed in a circular dot shape, but may be formed in a dot shape of an arbitrary shape without being limited to the circular shape. For example, as shown in FIGS. 3 and 4, it may be formed in a circular or rhombic shape. Further, it may be formed in a stripe shape. On the entire surface of the transparent light guide plate 2, a light diffusion layer 3 coated with a light diffusion material is disposed on the transparent light guide plate 2 as necessary. As a specific example of the light diffusion layer 3, there is a light diffusion film D204 manufactured by Kimoto Corporation. As the light diffusing layer 3, in addition to the above-described structure, a film having light diffusing properties, a milky white resin plate, or another material having the same effect may be used. Further, the white scattering reflection plate 4 can be formed by arranging a plate material painted white on the back surface of the transparent light guide plate 2. Further, the white scattering reflection plate 4 may be formed on a plate material different from the case or the like, and then disposed on the back surface of the transparent light guide plate 2. The white scattering reflector 4 does not adhere to a portion of the transparent light guide plate 2 where the diffusion transmitting portion 5 is not formed, and at least a slight gap is formed between the portion and the white scattering reflector 4. To do. Usually, it is only necessary to overlap a white plate on the surface of an acrylic plate as the transparent light guide plate 2, for example. Instead of using a white plate as the white scattering reflection plate 4, a surface of the case that houses the transparent light guide plate 2 and the light source 1 and the surface facing the transparent light guide plate 2 and the light source 1 is made of white paint having good scattering reflection efficiency. It may be painted or printed. Further, a white sheet and a metal foil bonded together may be used as the white scattering reflector 4.

【The invention's effect】

According to the present invention, since the diffusion transmitting portions are provided in a pattern having a density of 20 to 29 lines, defects such as clogging of the plate and blurring of the ink hardly occur, and the quality can be stabilized during mass production. Further, by forming the diffusion transmitting portion with a light diffusing material having a refractive index similar to that of the transparent light guide plate, scattering and reflection of light are performed efficiently, and a uniform surface light source without unevenness can be obtained. Further, by forming all the diffusion / transmission portions independently in the form of islands or by connecting them all in the form of a chain, stripes such as a density jump can be eliminated.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of the surface emitting device of the present invention. FIG. 2 is a plan view showing a conventional example. Third to fifth
FIG. 1 is a plan view showing an embodiment of the surface light emitting device of the present invention. 1 ... light source, 2 ... transparent light guide plate, 3 ... light diffusion layer, 4 ...
... White scattering reflector, 5... Diffuse transmission part, 6... Curved reflector.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G02B 6/00 331 F21V 8/00 601 G02F 1/13357

Claims (6)

(57) [Claims] 1. A surface light emitting device in which a white light scattering / reflecting plate is arranged on the back surface of a transparent light guide plate and a light source is arranged on a side surface of the transparent light guide plate to irradiate the transparent light guide plate with light from the light source. A surface light emitting device comprising a light transmitting plate and a diffusion / transmissive portion provided between the light scattering plate and the white scattering reflection plate in a pattern of a density of 20 to 29 lines so that the area gradually increases as the distance from the light source increases. 2. The surface light emitting device according to claim 1, wherein the diffuse transmission portion is formed of a light diffusion material having a refractive index similar to that of the transparent light guide plate. 3. The surface light emitting device according to claim 1, wherein all of the diffusion transmitting portions have independent patterns in an island shape. 4. The surface emitting device according to claim 1, wherein all of the diffusion transmitting portions have a pattern connected in a chain. 5. The surface light emitting device according to claim 1, wherein said diffusion transmitting portion has a dot-like or stripe-like pattern. 6. The surface light emitting device according to claim 1, wherein a light diffusion layer is disposed on a front side of the transparent light guide plate.