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. 27, 1993
Filed:
Oct. 16, 1991
Hiroshi Matsui, Kawasaki, JP;
Osamu Koyama, Kawasaki, JP;
Hideaki Yano, Kawasaki, JP;
Yasuo Nakamura, Musashino, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Canon Denshi Kabushiki Kaisha, Saitama, JP;
Abstract
The present invention is directed to a focus detector, one embodiment of which includes a light source, a collimator lens, a beam splitter and an objective lens. The light emitted by the light source is collimated by the collimator lens and subsequently passed through the beam splitter. The objective lens focuses the light passing through the beam splitter on a rotating disk. The light reflected by the disk passes through the beam splitter and is directed to a sensor lens. The sensor lens directs the light beam to an optical element arranged in a light path adjacent a refocus point of the light beam. The optical element is so arranged that the light beam is split only when it is not refocused at the expected refocus point.