Patent ID: 6967698

Claim:
A plane light source apparatus comprising: a light source; and a light guide plate for confining light from the light source and emitting the light from a surface thereof; wherein an optical sheet for reflecting light emitted from a rear face of the light guide plate in a skewed direction and making the light incident on the rear face of the light guide plate again orthogonally to the rear face is arranged opposite to the rear face of the light guide plate, wherein the optical sheet is formed with a recessed and projected pattern on a face thereof on a side opposed to a face thereof opposed to the light guide plate, and the face formed with the recessed and projected pattern defines a light reflecting face, wherein the rear face of the light guide plate is discretely formed with a diffusing pattern for reflecting light in the light guide plate, and the light reflected by the diffusing pattern is emitted from the surface of the light guide plate in a direction substantially orthogonal to the surface of the light guide plate, and wherein a directing angle of the light reflected by the optical sheet and then emitted from the light guide plate is narrower than a directing angle of the light reflected by the diffusing pattern and then emitted from the light guide plate.