Patent ID: 6157491
Filing Date: 2000-12-05
Classification: G03B

Abstract:
A lenticular lens sheet for use as a rear projection screen, said lens sheet comprising:a body sheet having a front surface and a back surface, said body sheet containing a light diffusing material forming a diffusing layer at least on said front surface;back lenses having a substantially elliptical cross section and formed in the back surface of the body sheet, said back lenses having focal points, respectively;front lenses formed in the front surface of the body sheet at the focal points of the back lenses, or in the vicinity thereof; anda light absorbing layer formed on sections of the front surface at the non-focal points of the back lenses;wherein the light absorbing layer is formed in a BS (Black Stripe) ratio meeting an inequality:BS.ltoreq.(1-2w/p).times.100(%)where:p presents pitches of the back and front lenses andw=(t-t.sub.D /2) tan {sin.sup.-1 (sin .beta..sub.F /n)}+t.sub.D /2.times.tan {sin.sup.-1 (sin .beta..sub.F /n)+sin.sup.-1 (sin .beta..sub.L /n)}.and t is a thickness of the lenticular lens sheet, t.sub.D is a thickness of the diffusing layer, n is a refractive index of the lenticular lens sheet, .beta..sub.F is a 1/3-luminance angle of diffusion of light rays before falling on the lenticular lens sheet (1), and .beta..sub.L is a 1/3-luminance angle of diffusion of light rays caused by the light diffusing material contained in the lenticular lens sheet.