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. 10, 2002
Filed:
Sep. 26, 2001
Kimiaki Nakazawa, Saitama, JP;
Tomoyuki Baba, Saitama, JP;
Fuji Photo Optical Co., Ltd., Saitama, JP;
Abstract
An afocal, wide converter lens is provided in order to shorten the focal length of a main lens, thereby shortening the projection distance that is needed to fully illuminate a given screen size when the wide converter lens is attached to the enlarging side of a main lens which functions as a projection lens of a projection apparatus. The wide converter lens is formed of, in sequential order in the direction from the enlarging side to the reducing side of the main lens, a lens element of positive refractive power, at least one lens element of negative refractive power, a positive meniscus lens element having its convex surface on the enlarging side, a negative meniscus lens element having its concave surface on the enlarging side, and a cemented lens of overall positive refractive power. Various conditions are satisfied in order that the wide converter lens does not degrade the optical performance of the main lens.