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:
Jan. 27, 2009
Filed:
Jul. 11, 2006
Masayasu Ito, Shizuoka, JP;
Fuminori Shiotsu, Shizuoka, JP;
Takanori Namba, Shizuoka, JP;
Koito Manufacturing Co., Ltd., Tokyo, JP;
Abstract
When a forward direction voltage of any of several LEDstois lowered, a drain voltage of an NMOS transistoremployed in any of series regulatorstobecomes higher than a defined voltage. A zener diode ZD, which is connected to the LED where the abnormal condition occurs, becomes conductive. A voltage, which is increased from the defined voltage, is applied to a negative input terminal of a comparing amplifier, and an output voltage of the comparing amplifieris lowered by this increased voltage portion so that a gate voltage of the NMOS transistoris lowered. A current flowing through the NMOS transistoris decreased. Even if an abnormal condition caused by a voltage drop occurs in any of the LEDsto, then the LEDstocan be protected.