Patent ID: 7535637

Claim:
A display apparatus, comprising: a light source for emitting incident light in a direction; and a Fresnel lens sheet for converting the incident light into parallel light, the Fresnel lens sheet comprising: a substrate having a light entrance face and a light emergence face; and a plurality of prisms arrayed on the light entrance face side of the substrate, each of the prisms having a refracting face for refracting the incident light, a reflecting face for reflecting the refracted light toward the light emergence face, and a passing face for passing the reflected light therethrough; wherein at least some of the prisms are configured such that; a first angle between a line perpendicular to the refracting face and a line perpendicular to the emergence face is smaller than a second angle between a line parallel to the direction of the incident light and the line perpendicular to the emergence face, and a third angle between a line parallel to the reflecting face and the line perpendicular to the emergence face is smaller than one-half of a fourth angle between a line parallel to a direction of the refracted light and the line perpendicular to the emergence face.