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. 09, 2002
Filed:
Mar. 02, 1999
Yoshio Tsuruta, Nagano, JP;
Fuji Electric Co., Ltd., Kawasaki, JP;
Abstract
An optical sensor circuit of the invention includes a photodiode, a reset switch, a capacitor for charge integration, an operational amplifier, reference voltage generating circuits connected to the operational amplifier via switches, and a reference voltage selecting circuit connected to the control input terminals of the respective switches. The reference voltage for defining the upper limit of the output range of the optical sensor circuit can be set at an appropriate value. Since the reference voltage is set at an appropriate value corresponding to the input range of an A/D converter due to this circuit configuration, a conversion error in the A/D converter is avoided, and the analog output of the optical sensor circuit is converted to a digital quantity while the resolution of the A/D converter is fully utilized.