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:
Feb. 28, 1989
Filed:
Jan. 28, 1987
Takashi Matsushita, Kanagawa, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A photographic lens comprising four lens units, of which the first and second counting from front are of positive power, and the third and fourth have powers of opposite sign to each other, wherein as focusing is performed from infinitely distant object to nearby object, the first three units are axially moved in such differential relation that all the three air separations between the successive two units increase, while the fourth lens unit is held stationary during focusing, thereby the picture quality for the nearby object is greatly improved.
Data source: USPTO (United States Patent and Trademark Office) public patent records. Weekly synchronization. How IDiyas builds this profile