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:
Jan. 11, 2000
Filed:
Oct. 09, 1998
Applicant:
Inventors:
Katsutoshi Tsurutani, Sakai, JP;
Katsuhiro Takamoto, Sakai, JP;
Assignee:
Minolta Co., Ltd., Osaka, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G02B / ;
U.S. Cl.
CPC ...
359689 ; 359683 ;
Abstract
A variable magnification optical system includes, from the projection side, a negative first lens unit, a positive second lens unit and a positive third lens unit. The magnification is varied by moving the first and second lens units along the optical axis. A lens element in the first lens unit and a lens element in the third lens unit are aspherical lens elements of which aspherical deviation is defined. A positive lens element in the third lens unit is made of a material of which anomalous partial dispersibility and Abbe number are defined.