Patent ID: 7344293

Claim:
A planar light source device comprising: a light source; a light guide opposed to the light source to guide light which is received from the light source; a frame which supports the light source and the light guide, and has a projection which positions the light source and the light guide; and an optical sheet which provides an optical property for light radiated from the light source, and has a regulation section that regulates contact between the light guide and the projection of the frame, the regulation section being located between the light guide and the projection. wherein the light guide has a first main surface from which light is to be emitted, a second main surface that is a back side of the first main surface and is opposed to the frame, and a side surface that extends between the first main surface and the second main surface and is opposed to the projection, and the optical sheet is opposed to one of the first main surface and the second main surface, and the regulation section has a tongue that extends from the optical sheet and is folded along the side surface of the light guide.