Patent ID: 6091469
Filing Date: 2000-07-18
Classification: G02F

Abstract:
A light reflector for use in a reflective-type liquid-crystal display that comprises a prism sheet, which is made from a transparent base material, the reverse side of said prism sheet having a plurality of unit prisms that are arranged with a fixed pitch in either one or two dimensions, external light that is incident at the surface of said transparent sheet being internally reflected by oblique surfaces of said unit prisms, so that it passes through said transparent base sheet and exits therefrom, wherein said unit prisms of the prism sheet have the shape of a triangle that has a base that is parallel to the reverse side of said prism sheet and a vertex that protrudes toward the side opposite said reverse side, and wherein if the angle that one of said oblique sides of said triangle makes with respect to a normal direction is .theta.1 and the angle that the other oblique side of said triangle makes with respect to said normal direction is .theta.2, the refractive index of said prism sheet material is n, and the angle of incidence of external light with respect to a light-diffusing layer on said transparent base material is .theta.0, under the condition that .theta.1>.theta.2, said light reflector for a reflective-type liquid-crystal display that satisfies the conditions.theta.2<90.degree.-sin.sup.-1 (1/n)and.theta.1=90.degree.-.theta.2+sin.sup.-1 (sin .theta.0/n)/2.2.