SURFACE LIGHT SOURCE DEVICE

摘要

PROBLEM TO BE SOLVED: To prevent the darkening of corner portions of a light incident face for a surface light source device using a comparatively small light source compared with the dimension of a light guide panel and make brightness distribution uniform by forming an optical pattern at an opposite place to the light source for the light incident face of the light guide panel which shuts in light led-in from the light incident face and extracts the light outward from a light emission face. SOLUTION: A light (f) emitted from a light emitting section opposed to an optical pattern 35 of a prism array state is not led into the light guide panel due to forward deflected light. The light is led to the inside of the light guide panel 22 in a wide range by refraction through each prism that constitutes the optical pattern 35. The light reaches even the corner portions of both sides of the light incident face 26 and the brightness distribution of the surface light source device is made uniform when the corner portions becomes bright. The light incident on the light guide panel 22 from the light emitting section is uniformly emitted at each region of the light guide panel 22 and uniform brightness distribution is obtained in the whole surface of the light guide panel 22 since a diffused pattern is formed at the bottom face of the light guide panel 22.