Patent ID: 6612710
Filing Date: 2003-09-02
Classification: G02B

Abstract:
A surface light source device comprising:a light guide plate, having a first major face serving as an emission face and a second major face serving as a back face opposite to said the emission face, and having end portion; and a primary light source disposed in the vicinity of the end portion of said light guide plate, said primary light source supplying light to said light guide plate to be emitted from said emission face, wherein a first light diffusion pattern is formed on said back face, said first light diffusion pattern having light diffusion elements distributed with a density which increases with increasing distance from said primary light source, a particular partial region and a surrounding region, around said particular partial region, are defined in said emission face, and a second light diffusion pattern is formed in said particular partial region so that said particular partial region provides a higher emission brightness as compared with that provided by the surrounding region.