Patent ID: 6211929
Filing Date: 2001-04-03
Classification: G02B

Abstract:
A surface light source device of side light type comprising:a guide plate having an emission face, a back face and an incidence face, said emission face being provided with a plurality of light scattering elements promoting emission from the emission face, the light scattering elements being distributed on the emission face with a covering rate varying depending on a position on the emission face;a primary light source arranged to supply said guide plate with primary light through said incidence face; anda reflection member arranged along said back face so as to return light leaked from said back face into said guide plate,wherein said reflection member has a reflection face which is directed to said back face and is provided with a plurality of fine regions having a scattering property which is different from that of a rest of the reflection face to control angular extension of illumination output, the fine regions being arranged so as to prevent the light scattering elements being distributed on the emission face from causing an angular extension of illumination output to vary depending on a position on the emission face.