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. 02, 2010
Filed:
Nov. 24, 2008
Akiko Nagahara, Saitama, JP;
Kimiaki Nakazawa, Saitama, JP;
Hiroshi Yamada, Saitama, JP;
Fujinon Corporation, Saitama-shi, JP;
Abstract
A projection zoom lens is provided and includes: in order from the magnification side, a positive first lens group performing focusing with being fixed during power-varying and having a focusing function; a negative second lens group, a negative third lens group, and a positive fourth lens group, which are moved with correlation during the power-varying; and a positive fifth lens group Gfixed during the power-varying. An aperture diaphragm is fixed between the fourth lens group and the fifth lens group during the power-varying. In addition, the expression of 1.7<Bf/f<3.0 is satisfied, where f is a focal length of the whole system, and Bf is a back focal length (air conversion distance) of the whole system.