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:
Sep. 25, 2012
Filed:
Nov. 24, 2009
Haruo Nagase, Nara, JP;
Takashi Kambara, Osaka, JP;
Haruo Nagase, Nara, JP;
Takashi Kambara, Osaka, JP;
Panasonic Corporation, Osaka, JP;
Abstract
An LED driver circuit is provided for protecting one (or more) LEDs connected in series from over-current damages which may result from a short circuit condition. The driver circuit includes a current control circuit for receiving an input signal from a power source and providing a current output for powering the LED. A voltage sensor detects a voltage across the LED. An LED current restriction circuit such as a switching element restricts a current flow into the LED. A short circuit response circuit controls the LED current restriction circuit dependent on a comparison between the voltage detected by the voltage sensor and a predetermined threshold value. When the detected voltage is less than or equal to the threshold value, the response circuit determines a short circuit, and a signal is sent to the current restriction circuit to restrict current flow into the one or more LEDs.