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:
Mar. 20, 1984
Filed:
Aug. 20, 1981
Applicant:
Inventor:
Yutaka Iizuka, Tokyo, JP;
Assignee:
Nippon Kogaku K.K., Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G02B / ; G02B / ;
U.S. Cl.
CPC ...
350454 ;
Abstract
A lens system comprises a converging first lens group, a diverging second lens group and a converging third lens group arranged in this order as viewed from the object side. The lens can focus continuously from infinity down to a very short object distance by moving only the diverging second lens forward and rearward along the optical axis. The paraxial rays exiting from the second lens group and incident on the third lens group are kept always substantially in parallel with the optical axis throughout all the moving range for focusing of the second lens group.