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:
Apr. 18, 1995
Filed:
Nov. 05, 1992
Noriyuki Iwata, Fujisawa, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
A varifocal lens system is constructed by two or more lens groups and has a function for changing a focal length of the lens system by changing a distance between the lens groups while the position of an image face is constantly held. An auxiliary lens constructed by two lens groups having negative and positive refracting powers is inserted into an increased clearance between lens groups in a shortest focal length state such that a lens group having the negative refracting power is located on an object side. The focal length of the lens system is transited to the side of a focal length shorter than the shortest focal length without changing the position of the image face by the insertion of the auxiliary lens. The auxiliary lens can be constructed by a single lens group having negative refracting power. In accordance with the above structure, focal lengths of the varifocal lens system can be transited to each other without increasing an entire length of the varifocal lens system.