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:
Mar. 17, 2009
Filed:
Oct. 17, 2005
Matthias Wendt, Wuerselen, DE;
Christoph Martiny, Aachen, DE;
Matthias Wendt, Wuerselen, DE;
Christoph Martiny, Aachen, DE;
Koninklijke Philips, N.V., Eindhoven, NL;
Abstract
A lighting device, and a lighting system including such a lighting device and an adjustable power source, includes at least one LED, a control device employing a device for measuring a quantity that is indicative of an electrical resistance of the LED at a predetermined current or voltage, a power supply control device for controlling an adjustable electrical power supply for driving the LED. The electrical resistance of a LED is functionally dependent of the LED's junction temperature, which in turn determines its optical output characteristics. Thus, by measuring the junction temperature indirectly, through measuring of electrical LED characteristics, and mapping them to a temperature, LED output control is possible.