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:
Feb. 04, 1997
Filed:
Aug. 08, 1995
Applicant:
Inventors:
Assignees:
Casio Computer Co., Ltd., Tokyo, JP;
Asahi Kogaku Kogyo Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G02B / ; G02B / ;
U.S. Cl.
CPC ...
359651 ; 359649 ; 359650 ; 359742 ;
Abstract
A projection lens assembly having an imaging lens group, including a first lens group having a positive refractive power, a second lens group having a positive refractive power, and a Fresnel lens group having a positive refractive power and at least one Fresnel lens surface, in this order from the enlargement side. The projection lens assembly satisfies the relationships 1.4<f.sub.1 /f<2.8, and 1.5<f.sub.2 /f<6.0. In these relationships, f represents the focal length of the whole lens system, f.sub.1 the focal length of the first lens group, and f.sub.2 the focal length of the second lens group.