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:
Aug. 20, 1991
Filed:
Jul. 31, 1990
Yuichiro Kanoshima, Tokyo, JP;
Ricoh Company, Ltd., Tokyo, JP;
Abstract
A reading lens system for a scanner is used at a reduced magnification so as to read an original image at a high speed, and comprises, successively in order from an object toward an image, a first lens unit to a fifth lens unit and an aperture disposed between the second lens unit and the third lens unit. The first lens unit comprises a positive lens serving as a first lens and a negative lens serving as a second lens and being cemented on an image side of the first lens. The second lens unit comprises a meniscus lens serving as a third lens, of which convex surface faces the object. The third lens unit comprises a meniscus lens serving as a fourth lens, of which convex surface faces an image. The fourth lens unit comprises a biconcave lens serving as a fifth lens and a biconvex lens serving as sixth lens and being cemented on the image side of the fifth lens. The fifth lens unit comprises a plane-parallel glass plate serving as a seventh lens. The lens system has the ratio f/f.sub.12 within the predetermined range where f is the focal length of the entire lens system, and f.sub.12 is the focal length of the first lens unit.