Patent ID: 7819572

Claim:
A planar light source device, comprising: a light guide plate that emits an entered incident light from a front surface thereof, the light guide plate including a convex positioning part disposed on a side surface thereof; a light source that emits light to a side surface of the light guide plate other than the side surface including the positioning part; a rear frame disposed on a back surface side of the light guide plate, the rear frame storing the light guide plate and the light source; and a mold frame having a frame shape and disposed between the light guide plate and the rear frame, the mold frame fitting with the light guide plate including the positioning part, wherein the positioning part includes a parallel surface almost parallel to the side surface of the light guide plate including the positioning part and includes connection surfaces that connect the parallel surface to the side surface of the light guide plate including the positioning part, the rear frame supports the light guide plate with the mold frame interposed therebetween and includes a projecting part projecting to an inside of the rear frame, the projecting part being formed of an end edge surface and a side edge surface, the end edge surface opposing the side surface of the light guide plate and the side edge surface opposing the connection surfaces, and the mold frame includes an opening therethrough and surrounds a periphery of the light guide plate.