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. 16, 2012
Filed:
May. 20, 2010
Applicant:
Isamu Fujii, Chiba, JP;
Inventor:
Isamu Fujii, Chiba, JP;
Assignee:
Seiko Instruments Inc., , JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H03F 3/08 (2006.01);
U.S. Cl.
CPC ...
Abstract
An electric charge storage method is used in which a photoelectric current generated in a photodiode is stored for a predetermined time period and the stored electric charge is amplified by an amplifier to obtain an output. Further, the storage time period is switched so that an output from the circuit has a characteristic of a piecewise linear approximation of a logarithm of an illuminance, permitting a sufficient resolution even in darkness.