Patent ID: 7455443

Claim:
A surface light source device comprising: a light guide plate having a light emitting plane at one end; and a light source arranged at a corner portion or side of the light guide plate, wherein a plurality of deflection patterns is formed on a first region in a plane opposite to the light emitting plane; the deflection pattern outputs light from the light emitting plane by reflecting the light guiding in the light guide plate; a diffusion pattern is formed on a second region that does not overlap the first region in the plane opposite the light emitting plane on the light source side of the deflection pattern; the deflection pattern and the diffusion pattern are formed so as not to protrude outside the light guide plate from the plane opposite to the light emitting plane; and the diffusion pattern diffuses the light incident from a light guide direction to a direction different from the light guide direction seen from a direction perpendicular to the light emitting plane.