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:
Dec. 21, 1993
Filed:
Nov. 07, 1991
Kenzaburo Suzuki, Tokyo, JP;
Yoshinari Hamanishi, Wako, JP;
Nikon Corporation, Tokyo, JP;
Abstract
Disclosed is a zoom lens of an internal focusing system, comprising: a positive focusing lens group positioned close to an object and incorporating a focusing function; and a zoom variable power optical system including a negative variable power lens group disposed towards an image of the focusing lens group and having such a variable power function as to be movable along an optical axis. The focusing lens group includes, sequentially from an object, a first lens element having a positive refractive power, a second lens element having a positive refractive power and movable along an optical axis and a third lens element having a negative refractive power. Only the second lens element is moved along the optical axis to change a synthetic focal distance of the focusing lens group, thus effecting focusing.