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:
Apr. 24, 2012
Filed:
Oct. 30, 2009
Applicant:
Kesanobu Kuwabara, Azumino, JP;
Inventor:
Kesanobu Kuwabara, Azumino, JP;
Assignee:
Fuji Electric Co., Ltd., , JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H05B 37/02 (2006.01);
U.S. Cl.
CPC ...
Abstract
A drive circuit drives LED groups each of which has a plurality of LEDs connected in series. The drive circuit includes nMOSFETs which drive the LED groups, current regulating circuits which determine drain currents of the nMOSFETs, and subtracters which control the current regulating circuits to keep the sum of the current values of adjacent two nMOSFETs constant. The LEDs can be switched on/off efficiently even when there are differences between forward voltages of the LEDs.