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. 24, 1985
Filed:
Apr. 29, 1985
Takao Kinoshita, Tokyo, JP;
Takashi Kawabata, Kanagawa, JP;
Kazuya Hosoe, Tokyo, JP;
Tokuichi Tsunekawa, Yokohama, JP;
Toshio Sakane, Yokohama, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
In the device disclosed, an image formed by an optical system is scanned by an image sensor composed of independently arranged photoelectric transducing elements to produce an image scanning signal. A detecting circuit detects the variation of the brightness between the adjacent image elements as a measure of the sharpness of the image and the focus of the optical system. The focus detection accuracy is improved by non-linear transformation of the brightness variation signal with a non-linear transformation circuit that weighs the brightness variation signal on the basis of the signal level. A signal forming circuit detects the difference between the outputs of transducing elements and adds the differences to produce a comparator signal when a predetermined relationship is reached between the sharpness indication and the addition signal. An indicator indicates that the focusing condition cannot be discerned in response to the comparison signal and a control inhibits the output of the detection circuit to the indicator prior to the addition signal.