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:
Aug. 14, 2001
Filed:
Apr. 17, 2000
Applicant:
Inventors:
Katsuhiro Takamoto, Sakai, JP;
Jun Nishikawa, Sakai, JP;
Assignee:
Minolta Co., Ltd., Osaka, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G02B 9/00 ; G02B 1/304 ;
U.S. Cl.
CPC ...
G02B 9/00 ; G02B 1/304 ;
Abstract
A projection optical system has, from the enlargement side to the reduction side, a first, a second, and a third lens unit, and an aperture diaphragm. The negatively-powered first lens unit includes only a negative lens element and has at least one aspherical surface. The positively-powered second lens unit includes at least one positive lens element. The positively-powered third lens unit includes a lens element. The aperture diaphragm is disposed at the front focal point of the third lens unit. The lens element of the third lens unit is made of a material of which anomalous partial dispersibility and Abbe number are defined.