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. 21, 1982
Filed:
Apr. 10, 1980
Shozo Ishiyama, Hachioji, JP;
Abstract
A compact zoom lens of mechanical compensation type is described which comprises first, second, third and fourth lens groups arranged so that variation of image position caused when the second lens group is moved along the optical axis for the purpose of varying the focal length is compensated by moving the third lens group so as to form a locus of points concave toward the object side. The zoom lens as a whole is made compact by compactly arranging the vari-focal lens groups, which comprise the first through third lens groups, by making the amounts of movements of the second and third lens groups small and by arranging the vari-focal lens group itself so that the focal length of the fourth lens group becomes short.