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:
Oct. 22, 1991
Filed:
Dec. 19, 1990
Shuichi Kikuchi, Yokohama, JP;
Masami Itoh, Tokyo, JP;
Ricoh Company Ltd., Tokyo, JP;
Abstract
A compact zoom lens has a first lens group having a negative focal length f.sub.1 ; a second lens group having a positive focal length f.sub.2 ; and a third lens gorup having a negative focal length f.sub.3. The first, second and third lens groups are sequentially arranged from an object side of the zoom lens to an image side thereof. The first to third lens groups are moved on the object side while the mutual distances between the first, second and third lens groups are changed to perform a zooming operation from a wide angle side to a telescopic side. The third lens group is constructed by positive, negative and positive lenses sequentially arranged from the object side to the image side such that the negative and positive lenses respectively constituting the second and third lenses are joined to each other. The focal lengths f.sub.1, f.sub.2, f.sub.3 and a focal length f.sub.w of an entire lens system at a wide angle end of the zoom lens satisfy the following conditions.