Patent ID: 8345184

Claim:
A surface light source apparatus comprising a point light source, and a light guide plate for introducing light of the point light source from a light incident surface and outputting to an outside from a light outputting surface; wherein the point light source is arranged at a position facing the light incident surface of the light guide plate; the light guide plate includes a light introducing section for confining the light from the point light source entered from the light incident surface, and a light guide plate main body, which has a thickness smaller than a maximum thickness of the light introducing section and being arranged to continue with the light introducing section, for outputting the confined light to the outside from the light outputting surface by light outputting means; the light introducing section has an inclined surface, which is inclined toward an end of a surface of the light guide plate main body from a surface of a portion having a greater thickness than the light guide plate main body, on a surface on the light outputting side of the light guide plate or on an opposite surface thereof; and the light guide plate has a directivity converting pattern, for converting a directivity expansion in a thickness direction of the light guide plate of the light entered to the light introducing section to directivity characteristics tilted toward a direction parallel to a surface direction of the light guide plate, on the surface on the light outputting side or on the opposite surface thereof.