JPH04178627A - Production of panel light source - Google Patents

Abstract

PURPOSE:To obtain the more uniform and brighter brightness distribution on a diffusion surface by disposing a light transmission body which is disposed with a light source and the light diffusion surface on a front side and is disposed with a reflection surface on a rear surface side in proximity to the light source and forming the patterns consisting of light diffusive milky white coated films by hot stamping on the rear surface side of this light transmission body. CONSTITUTION:The rugged rough surface layer formed by embossing or the milky white layer 5 formed of ink, etc., is formed by hot stamping between the light transmission body 2 and a reflection sheet 4, i.e. the rear side of the light transmission body 2. This layer 5 consists of the patterns formed of the arrangement of rhombic shapes or rectangular shapes having some area in the rough surface parts or the milky white parts 6. The patterns are arranged at a specified pitch; in addition, the patterns are so formed that the sizes thereof are smaller and the arranging density thereof is smaller the furtherer from the light source 1. The patterns can be formed to the smaller sizes and the smaller inter-pattern pitch and the deposited layers can be formed thinner by using the hot stamping to transfer the printed patterns by pressing a transparent base material, such as acrylic resin, with a heated mold from the surface to be printed of this material. The good reproduction accuracy of the patterns is, therefore, obtd. and the brightness distribution is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a surface light source device that uses a light guide in a surface light source device used as a backlight of a liquid crystal display device or the like.

[Prior Art] Among conventional surface light sources, a light guide type surface light source device in which a light guide made of a transparent resin made of acrylic, polycarbonate, etc. is disposed close to a cold cathode tube isoline light source is the first one. As shown in the figure, a diffuser plate 3 is formed on the front side of the light guide 2, and a reflective plate 4 is formed on the back side of the light guide 2.

In this conventional surface light source device, light from a light source 1 enters the light guide 2 from an end surface 2a, is sequentially reflected by the front surface and the reflective surface, and is sequentially transmitted to the opposite side 2b of the light guide end surface 2a. While being transmitted, a part of the light is scattered by the diffusion surface 3 and diffused out to the outside of the light guide 3 as diffused light.

In a surface light source device using such a light guide, the light transmitted through the light guide gradually decreases, and the amount of light decreases as you move away from the light source, so the brightness on the diffuser plate decreases as you get closer to the light source. This is accompanied by a phenomenon in which the light intensity decreases as the distance from the light source increases, so in order to compensate for these drawbacks, it has been conventionally possible to use screen printing to create spots or net-like patterns on one side of the light guide, which is the reflective surface. The distance between the patterns closer to the light source is increased (smaller density), and the distance between the patterns is made smaller (higher density) as the distance from the light source increases. By gradually increasing the pattern size from small (small area) to large (large area) as you move away from the near side, the degree of diffusion of the reflected light on the reflective surface side is varied, and the pattern size on the side far from the light source is varied. The degree of diffused light is increased to make the brightness uniform on the diffused surface.

[Problems to be Solved by the Invention] By the way, when the above-mentioned screen printing is adopted, all types of inks (e.g., evaporation, oxidative polymerization, two-component reaction type, UV, and water-based inks) can be used because the printing method is simple. It is easy to use, has good reproducibility, and can be easily printed on both hard and soft objects with low printing pressure.

On the other hand, however, the inked layer 5 is thick, and when attempting to form various patterns such as spots or nets, there is a problem in that it is not possible to reduce the pitch between adjacent spots in the pattern.

The purpose of the present invention is to make the luminance distribution on the diffusing surface more uniform.
It is an object of the present invention to provide a surface light source device that forms a diffusion pattern on one surface of a light guide in a more preferable state so that the light becomes brighter. The surface light source device has a light source and a light guide with a light diffusing surface on the front side and a reflective surface on the back side arranged close to the light source, and a diffuse milky white light source formed on the back side of the light guide. This method attempts to form a pattern consisting of a coating layer using hot stamping.

[Embodiment 1] Next, an embodiment of the surface light source device of the present invention will be described based on the drawings. FIG. 1 is a sectional view of an example of a surface light source device which is a premise for implementing the present invention, where ■ is a linear light source such as a cold cathode tube,
3 is a light guide, and 3 is a diffusion sheet 4 is a reflection sheet, which are substantially the same as those of a conventional surface light source device. Figure 2 shows the first
This is an enlarged cross-sectional view of part A of the light guide of the device, and there is a textured surface between the light guide 2 and the reflective sheet 4, that is, on the back side of the light guide 2, as shown in FIGS. 3 and 4. A rough surface layer 5 having an uneven surface or a milky white layer 5 made of ink or the like is formed by hot stamping. This rough surface layer or milky white layer 5 has a rough surface portion or milky white portion 6 as shown in FIGS. 3 and 4.
consists of a pattern formed by an array of rhombuses or rectangles with a certain area, arranged at a constant pitch,
In this case, the size of the light source 1 decreases as it moves away from the light source 1, and the density of the array becomes fine. By using hot stamping to transfer the pattern, it is possible to reduce the size of the pattern and the pitch between patterns, and to form a thin ink layer, resulting in good pattern reproduction accuracy and improved optical properties (brightness distribution). Is possible.

Furthermore, by using Bott stamping, it is not only possible to print on a flat light guide plate, but also to effectively print when a curved light guide plate is to be formed due to design considerations.

[Effect of the invention 1] According to the surface light source device of the present invention, the brightness on the diffusing surface of the light guide surface can be made uniform, and the uniformity almost in accordance with the designed value can be reliably obtained. be.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an example of a surface light source device which is a prerequisite for carrying out the method of the present invention, FIG. 2 is an enlarged sectional view of part A of the light guide of the device shown in FIG. FIG. 6 is a plan view showing a second embodiment showing a pattern of a surface layer or a milky white layer. 1--Light source, 2--Light guide, 3--Diffusion sheet 4
... Reflective sheet, 5... Rough surface or milky white layer 6--
Rough surface area or milky white area

Claims (1)

[Claims] A light source, a light guide having an incident end face disposed close to the light source and having an appropriate pattern having a diffusing effect formed on one surface, a diffusing surface provided on the surface side of the light guide, and 1. A method of manufacturing a surface light source device comprising a reflective surface provided on the back side, the method comprising: forming a diffusion pattern provided on the light guide by hot stamping printing.