Light conducting plate

Abstract

A light guide plate is a light guide plate with a diagonal size of 14 inches to 30 inches obtained by using a mold with a pattern on at least one inner cavity surface and injecting molten transparent resin into it for molding. At least one of the surfaces has a transferred reflective or light-scattering pattern, the birefringence value in the thickness direction is 9×10-6 or less, and the deviation is within ±3×10-6 relative to the average value. The light guide plate transfers the pattern on the cavity surface of the mold onto the surface of the light guide plate at a transfer rate of more than 90%, and the deviation of the transfer rate is within ±2% relative to the average value. Therefore, the present invention provides a large pattern for reflection or light scattering, which can be molded directly by molten resin without warping or deformation after molding, and can be transferred and shaped with high precision for reflection or light scattering. Scattering patterned light guide plate.

Description

technical field [0001] The present invention relates to a light guide plate (Light Transmitting Plate) used in the backlighting of a liquid crystal display. In particular, it relates to large light guide plates with a pattern on the surface for reflection or light scattering and with a diagonal dimension of 14 inches or more. Background technique [0002] The light guide plate is used as an optical device for guiding light from a light source arranged on the side to the liquid crystal display surface in liquid crystal displays such as notebook personal computers, desktop personal computers, and liquid crystal televisions. exist figure 1 The configuration of the liquid crystal display and the light guide plate is shown in a schematic cross-sectional view. The backlighting arranged on the back of the liquid crystal display 1 is mainly composed of light guide plates 2 and 3; the reflective layer 4 arranged on its back; the light scattering layer 5 arranged on the front of the...

AI Technical Summary

Problems solved by technology

[0008] However, in the method of cutting a methacrylic resin extruded plate with a certain thickness to make a light guide plate, it is necessary to additionally provide a reflective layer or a light scattering layer, or to print a pattern replacing these layers, which requires many steps and high cost.

In addition, since the thickness accuracy of the methacrylic resin plate is not so good, it becomes the cause of uneven printing at the time of printing, and a gap occurs when assembling it into the frame, making it impossible to assemble

In addition, in the laser scribing process, it is not satisfactory because the heat of the laser causes the end surface of the board to sag easily, etc., which is not a problem in the injection molding method.

[0009] On the other hand, the method of manufacturing by injection molding can be shaped while forming the pattern for reflection or light scattering, and the process is less, and it is also a preferable method in terms of cost. However, for large guides with a diagonal dimension exceeding 14 inches The size of the product is too large for the light board, and as mentioned above, high-quality products cannot be obtained by the conventional injection molding method

In addition, the light guide plate produced by the conventional injection molding method has the following problems in addition to the above-mentioned problems: the pattern transferability is poor, and the pressure acting on the product during the molding process becomes more uneven, and the stress inside the molded product ( Molding distortion) increases and becomes the cause of warpage or deformation in the product stage

Moreover, the light guide plate shows a tendency to reduce the pattern retention rate after the environmental test for determining durability, that is, the durability is poor, and effective light reflection and emission are hindered, and it is difficult to express the required brightness performance.

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