Light diffusion sheet and backlight unit using that

Abstract

An object of the present invention is to provide a light diffusion sheet having a favorable cost reduction capability due to excellent scratching preventive property of the front face, and having in addition thereto, a favorable directional light diffusion function, transmittivity of rays of light, and a thin film character; and a backlight unit capable of promoting performances such as luminance as well as price reduction, and thin and light modeling capability. The light diffusion sheet of the present invention has a light diffusion sheet including a transparent substrate layer, and a light diffusion layer overlaid on the front face side of the substrate layer, wherein the light diffusion layer has resin beads and a resin binder, characterized in that the light diffusion layer has protruding parts having a shape of a partial spherical body on the front face in a scattering manner. It is preferred that mean height of the protruding parts be 1 mum or greater and 10 mum or less, mean diameter of the protruding parts be 4 mum or greater and 18mum or less, mean occupancy rate of the protruding parts be 2% or greater and 20% or less, and surface roughness (Ra) of the light diffusion layer be 1.5 mum or greater and 10 mum or less. As the beads, small monodisperse beads as a principal component, and large beads as a sub component may be included.

Description

technical field [0001] The present invention relates to a light diffusion sheet having a directional light diffusion function of converging and diffusing transmitted light toward the normal direction, and is particularly suitable for a backlight unit of a liquid crystal display device, and a backlight unit using the light diffusion sheet. Background technique [0002] In a liquid crystal display device, a backlight method in which a liquid crystal layer is irradiated from the back to emit light is popularized, and a backlight unit such as an edge-firing type or a direct-type type is mounted below the liquid crystal layer. The edge-firing type backlight unit 50 basically has a linear lamp 51 as a light source as shown in FIG. The light-diffusing sheet 53 on the side is arranged on the prism sheet 54 on the front side of the light-diffusing sheet 53 . [0003] The function of the backlight unit 50 will be described. First, the light incident on the light guide plate 52 from t...

AI Technical Summary

Problems solved by technology

[0008] However, in the above-mentioned conventional light-diffusing sheet 53, hemispherical protrusions are formed closer to the surface of the light-diffusing layer 57 due to the particle size distribution, average particle diameter, and mixing amount of the above-mentioned beads 59. Continuous damage occurs on the surface of the light-diffusing layer 57 during the process or assembly process of the LCD, which may lead to a decrease in product yield.

The reduction in the product yield of the light diffusing sheet 53 is the result of the opposite of the above-mentioned low price of the LCD.

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