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:
Jan. 11, 1994
Filed:
Jun. 19, 1992
Haruhiro Hyodo, Toyohashi, JP;
Hideyuki Kurahashi, Toyohashi, JP;
Abstract
A zoom lens system, for use in a copying apparatus, is provided with, from the object side, a first lens unit of a negative power including a negative lens element, a second lens unit of a positive power including a positive lens element and a negative meniscus lens element concave to the image side, an aperture stop, a third lens unit arranged symmetrically with the second lens unit with respect to the aperture stop, and a fourth lens unit arranged symmetrically with the first lens unit with respect to the aperture stop. The second lens unit and the fourth lens unit are moved in a same direction in association with each other so that the total length of the zoom lens system is minimum at unity magnification. The aperture stop moves so that the symmetry of the entire zoom lens system is maintained. An object-image distance is maintained constant by moving the entire zoom lens system.