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:
May. 13, 2014
Filed:
Apr. 07, 2011
Satoshi Machida, Chiba, JP;
Satoshi Machida, Chiba, JP;
Seiko Instruments Inc., Chiba, JP;
Abstract
Provided is an illuminance sensor in which a consumption current is independent of an illuminance level of incident light. Amplifiers (to) and a subtraction circuit () are driven by a constant current source (not shown). The subtraction circuit () outputs a differential voltage between output voltages of a photodetector element () and a photodetector element (). Based on the differential voltage, a sample/hold circuit () performs sampling or holding of a voltage at one end of a capacitor (). A switch () is ON when an output voltage of the subtraction circuit () starts to change, thereby fixing the voltage at the one end of the capacitor () to a reference voltage.