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:
Mar. 10, 1987
Filed:
Jul. 25, 1983
Hiroto Terashi, Tokyo, JP;
Asahi Kogaku Kogyo Kabushiki Kaisha, Tokyo, JP;
Abstract
An iris control circuit for a video camera in which only a single drive coil is employed so that the video camera employing the circuit can be more easily miniaturized. A first operational amplifier supplies drive current to a drive coil in proportion to the sum of an iris control signal and a feedback signal. A detecting circuit, preferably implemented as a voltage divider circuit, detects the counterelectromotive force developed across the drive coil. A feedback circuit, which may be implemented with a second operational amplifier, develops the feedback signal. The feedback signal can be made variable to adjust the feedback ratio, and hence the proportional braking force applied to the iris.