Fresnel lens sheet for rear projection screen

Details Fresnel lens sheet for rear projection screen Fresnel lens sheet for rear projection screen

1997-07-11

2000-04-18

Metjahic, Safet

Optical: systems and elements

Projection screen

Unitary sheet comprising plural refracting areas

359443, G03B 2160, G03B 2156

Patent

active

060522267

ABSTRACT:
A Fresnel lens sheet of a multifocal type is intended to be used in combination with a lenticular lens sheet to construct a rear projection screen for a rear projection television receiver. An annular portion (2) of the Fresnel lens sheet at a distance (R) in a range of 0.05 h to 0.5 h, where h is the height of the Fresnel lens sheet, from the optical center (C) of the Fresnel lens sheet, have the shortest focal length f.sub.min among those of other portions of the Fresnel lens sheet, whereby uniformity in brightness of a screen employing the Fresnel lens sheet can be achieved. Alternatively, a portion where an exit angle (.theta.) of outgoing light ray relative to a normal to the surface of the Fresnel lens sheet is the greatest, lies at a distance (R) in a range of 0.3 h to 0.8 h from the optical center (C) of the Fresnel lens sheet, to obtain the same result.

REFERENCES:
patent: 3004470 (1961-10-01), Ruhle
patent: 4012136 (1977-03-01), de la Croix et al.
patent: 5146342 (1992-09-01), Yokoo et al.
patent: 5803567 (1998-09-01), Nakanishi
Patent Abstracts of Japan, vol. 006, No. 027 (P-102), Feb. 17, 1982 & JP 56 147140 A (Matsushita Electric Co. Ltd.), Nov. 14, 1981, *abstract* *Figures 1-5*.
Patent Abstracts of Japan, vol. 017, No. 143 (P-1507), Mar. 23, 1993 & JP 04 316010 A (Seiko Epson Corp.), Nov. 6, 1992, *abstract* Figure 3*.

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