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. 31, 1990
Filed:
Dec. 27, 1988
Shinji Nagaoka, Yotsukaido, JP;
Yoichi Seki, Yotsukaido, JP;
Hiroyuki Saito, Yotsukaido, JP;
Michio Taniwaki, Yotsukaido, JP;
Seikosha Co., Ltd., , JP;
Abstract
A circuit for detecting back light comprises a time constant circuit including a capacitor selectively connectable in series with either a resistive element, or one of two CdS photoconductive elements used to measure the central and surrounding portions, respectively, of an object being photographed. Three switches separately conect the resistive element and the two photoconductive elements in series with the capacitor. A circuit generates pulses for a length of time governed by a time constant determined by the time constant circuit, and three separate counters store the pulses the number of which is determined by the time constant. An arithmetic circuit processes the pulses stored in the counters to determine the amount of back light present on the object.