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:
Dec. 20, 1977
Filed:
Dec. 19, 1975
Yutaka Iizuka, Yokohama, JA;
Soichi Nakamura, Kamakura, JA;
Nippon Kogaku K.K., Tokyo, JA;
Abstract
A zoom lens system for a projector has three groups of lenses. The first lens group closest to the object has a composite converging function achieved by a doublet consisting of a first positive lens and a first negative lens. The second lens group is located between the other groups and is movable along the optical axis of the lens system relative to the other groups for varying magnification. It has a composite diverging function achieved by a doublet consisting of a second negative lens and a second positive meniscus lens. The third lens group most remote from the object has a composite converging function achieved by a third biconvex positive lens, a fourth positive lens, a forward meniscus lens consisting of a fifth positive lens joined to a third negative lens and having the convex surface thereof facing the object, a rearward meniscus lens consisting of a fourth negative lens joined to a sixth positive lens and having the concave surface thereof facing the object, a seventh biconvex positive lens, and an eighth positive lens.