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:
Jul. 19, 1994
Filed:
Nov. 05, 1991
Applicant:
Inventor:
Koutaro Yano, Yokohama, JP;
Assignee:
Canon Kabushiki Kaisha, Tokyo, JP;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G02B / ; G02B / ; G02B / ;
U.S. Cl.
CPC ...
359689 ; 359651 ; 359716 ; 359784 ;
Abstract
In a retro-focus type lens divided into three lens units by the widest air spacing and the next widest air spacing, a first lens unit is disposed on a long conjugate side and has negative refractive power, and includes a negative lens and a lens provided with an aspherical surface, a second lens unit is disposed subsequently to the first lens unit and provided with a positive lens block, and a third lens unit is disposed subsequently to the second lens unit and has positive refractive power, and includes a negative lens and a positive lens.