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. 20, 1990
Filed:
May. 02, 1989
Shuichi Kikuchi, Yokohama, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
A zoom lens comprises a front lens group having a positive focal length and a rear lens group having a negative focal length, with the distance between the front and rear lens groups being variable for varying the magnification of the zoom lens. The front lens group comprises a first front lens group having a negative focal length and a second front lens group having a positive focal length, the first and second front lens groups being successively arranged in the order specified from an object side. The first front lens group comprises, in the order named from the object side, at least a positive lens and a negative lens. The second front lens group comprises at least one negative lens and at least two positive lenses. The rear lens group comprises, in the order specified from the object side, a positive lens, a negative lens, a negative lens, and a positive lens. The distance between the first and second front lens groups varies during zooming movement of the zoom lens.