| 摘要 |
PURPOSE: A light diffusion plate and a direct type point light source light backlight apparatus used for a backlight are provided to obtain good brightness and regularity of brightness using small number of point light sources. CONSTITUTION: A light diffusion plate(1) has a plurality of concave parts on a surface. The concave part is shape like an inverse polygonal cone or a reverse trapezoid shape. In one or more inner sides among the concave part is the opening edge part, it is composed of a curved face in which the curvature center locates in the depth directivity of the concave part.
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