Surface light source device

摘要

A surface light source device having light sources provided along all four side edges of a light-conducting member. A light guide has a diffusion plate on its front surface and a reflection surface on its back surface. The back surface of the light-conducting member has a pattern consisting of tiny rough surface areas. The pattern is so formed that in a direction of connecting a pair of two opposed sides of the light-conducting member, the density of the rough surface areas is the largest in the center portion, but gradually decreases toward the two opposed side edges and reaches the smallest density on the two opposed side edges. Thus, the surface light source device increases the brightness and provides a uniform distribution of brightness.