The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 25, 1989
Filed:
Nov. 20, 1985
Applicant:
Inventors:
Jill F Goldenberg, Pelham Manor, NY (US);
T Stewart McKechnie, Ossining, NY (US);
Assignee:
North American Philips Corporation, New York, NY (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G02B / ;
U.S. Cl.
CPC ...
350452 ;
Abstract
a Fresnel lens for use in rear projection screens wherein said lens has a plurality of facets facing away from the light source and each of said facets has an optimal riser angle, said riser angle varying from the center to the outer edge of said lens as a function of the focal length the refractive index, the angular subtense of the exit pupil and the radial distance from the center of the lens, thereby improving the efficiency of the Fresnel lens.