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:
Oct. 15, 1985
Filed:
Apr. 05, 1984
Nozomu Kitagishi, Kawasaki, JP;
Shin Yamaguchi, Hiratsuka, JP;
Shinji Sakai, Tokyo, JP;
Takao Kinoshita, Tokyo, JP;
Takashi Kawabata, Kamakura, JP;
Nobuhiko Shinoda, Tokyo, JP;
Kazuya Hosoe, Machida, JP;
Canon Kabushiki Kaisha, Tokyo, JP;
Abstract
A focus detecting apparatus is disclosed which includes a focusing optical system for forming an object image on a predetermined focal plane and photoelectric devices disposed before and behind the focal plane at substantially equal distances from the plane. The photoelectric devices detect the focus states of the object images formed thereon respectively. The focus state of the object image on the focal plane is detected depending on whether or not the focus states on the photoelectric devices are equal to each other. According to the invention such a focus detecting apparatus further includes a mask for gradually decreasing the quantity of light incident upon the photoelectric devices in the direction away from the center of the incident beam. Under the action of such a mask, the focus states of object images before and behind the predetermined focal plane at substantially equal distances from the focal plane are made approximately equal to each other.