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:
Sep. 07, 1999
Filed:
Mar. 06, 1998
Kimiaki Nakazawa, Omiya, JP;
Fuji Photo Optical Co., Ltd., Saitama, JP;
Abstract
Negative, positive, and positive lens groups are disposed successively from the larger conjugate length side, and focal length adjustment is effected by the convex lens disposed on the smallest conjugate length side of the first lens group, thereby yielding a long back focus and a telecentric characteristic, decreasing distortion and chromatic aberration, and simplifying the focusing structure. Successively from the larger conjugate length side, a first lens group G.sub.1 having a negative refracting power and including a convex lens L.sub.5 disposed on the smallest conjugate length side, a second lens group G.sub.2 having a positive refracting power and causing a luminous flux diverged by the first lens group G.sub.1 to become substantially afocal, and a third lens group G.sub.3 having a positive refracting power are disposed, and the convex lens L.sub.5 disposed on the smallest conjugate length side of the first lens group G.sub.1 is moved on an optical axis so as to effect focus adjustment.