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. 04, 2012
Filed:
Apr. 15, 2008
Geert Willem Van Der Veen, Eindhoven, NL;
Johan Wilhelmus Hermanus Kuppen, Eindhoven, NL;
Marco Foggi, Eindhoven, NL;
Geert Willem Van Der Veen, Eindhoven, NL;
Johan Wilhelmus Hermanus Kuppen, Eindhoven, NL;
Marco Foggi, Eindhoven, NL;
Koninklijke Philips Electronics N.V., Eindhoven, NL;
Abstract
A lighting device () comprises a LED (), a driver (), and a controller () which regularly switches from a drive state to a measuring state and back. In the measuring state, the controller controls the driver such that the driver does not generate any LED current. The LED produces a measuring signal (Sm) indicating a measured light level. The controller processes the measuring signal received from the LED, and makes a decision on the desired light output of the LED. In the drive state, the controller controls the driver such that the average light output produced by the LED corresponds to the desired light output as determined in the measuring state. In a possible embodiment, the driver generates a nominal LED current I, and sets the duration (τ) of the drive state on the basis of the desired light output of the LED as determined in the measuring state.