Patent ID: 7520652

Claim:
A planar light source device comprising: a primary light source; a light guide guiding a light emitted from the primary light source and having a light incident end face on which the light emitted from the primary light source is incident and a light emitting face from which the light guided in the light guide is emitted; a light deflector arranged adjacently to the light emitting face of the light guide and has a light entering face which the light emitted from the light emitting face of the light guide enters and a light exiting face located on the opposite side to the light entering face; and a direct light incoming prevention means composed of a light-blocking member wherein the light-blocking member is arranged on a first region of the light emitting face of the light guide, the first region being located near an edge of the light emitting face on the side of the light incident end face, and prevents the light, which is emitted from the primary light source, from entering the light deflector without passing through the light guide, a surface of the light-blocking member facing the light emitting face of the light guide is a diffusing reflective surface, and the light deflector is arranged on a second region of the light emitting face where the light-blocking member is not contacting the light emitting face and the light deflector is sandwiched between the light-blocking member and the light emitting face, and wherein the light-blocking member contacts a portion of the light exiting face of the light deflector.