Patent ID: 6086211
Filing Date: 2000-07-11
Classification: F21V,G02B

Abstract:
A surface light source device of side light type comprising:guide plate having an emission surface, a side end surface and a back surface;a primary light source supplying illumination light to the side end surface of the guide plate; anda light control member disposed along the emission surface of the guide plate so as to correct directivity of illumination light that has been emitted from the emission surface, the light control member having a surface opposing the guide plate,the emission surface of the guide plate having a large number of projections each of which extends in a direction generally orthogonal to the side end surface;the surface of the light control member opposing the guide plate having a large number of projections each of which extends in a direction generally parallel with the side end surface of the guide plate; andeach projection of the light control member having a first slope relatively remote from the side end surface of the guide plate and a second slope relatively near to the side end surface of the guide plate,the angles of inclination .beta.1, .beta.2 of the first and second slopes respectively being defined with respect to a normal erected on a general surface of the guide plate, the angle of inclination .beta.2 being small compared with angle of inclination .beta.1.