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:
May. 03, 2016
Filed:
Feb. 09, 2015
Yoshifumi Sudoh, Saitama, JP;
Yoshifumi Sudoh, Saitama, JP;
RICOH COMPANY, LTD., Tokyo, JP;
Abstract
A zoom lens includes, in order from an object side to an image side, first, second, third, and fourth lens groups with positive, negative, negative, and positive refractive powers, respectively. When varying magnification from a short focal length end to a long focal length end, the second lens group is moved to the image side, the third lens group is moved, and the first and fourth lens groups are fixed. The fourth lens group is constituted of a lens group on the object side and a lens group on the image side with a largest distance in the fourth lens group between them. Each of a refractive index, Abbe number, a partial dispersion ratio, and the like of each of at least one positive lens of the lens group on the object side and two positive lenses of the first lens group is regulated to be in a predetermined range.