Patent ID: 7978285

Claim:
A surface light source comprising: a light source which selectively irradiates two polarized light beams in polarized states different from each other; a light guide plate comprising a transparent plate having two plate surfaces facing each other, the light guide plate guiding two light beams selectively irradiated from the light source into the transparent plate upon allowing the light to enter from an end face of the light guide plate, and irradiating the light from an irradiation surface which comprises one of the two plate surfaces; and an optical element which irradiates irradiated light from the irradiation surface of the light guide plate in a direction substantially normal to the light guide plate upon changing a propagation direction of the irradiated light; wherein the light source comprises: a first light-emitting element and a second light-emitting element which are arranged on the end face of the light guide plate so as to face each other; a first polarizing element which is provided between the first light-emitting element and the end face of the light guide plate and has a transmission axis in a direction substantially perpendicular to the irradiation surface of the light guide plate; and a second polarizing element which is provided between the second light-emitting element and the end face of the light guide plate and has a transmission axis in a direction substantially parallel to the irradiation surface of the light guide plate.