Flextronics International Kft.

Rainer Kümer

Frank Wimbert

Uwe Burkhardt

Tobias Gern

A method for obtaining PWM values for an LED module having n LED chips from various color ranges, wherein n&#x3e;1, wherein for each LED chip a PWM value for producing a target color value is obtained, is characterized in that a calibration measurement is performed in which the wave lengths (&#x3bb;, &#x3bb;, &#x3bb;) and/or the standard color proportion values ((x,y), (x,y), (x,y)) and possibly the luminous flux values of the individual LED chips are determined at a calibration temperature (T), PWM control points are obtained, where each PWM control point contains a PWM value for each of the n color ranges of the LED module, during operation of the LED module a value that depends on the present temperature (T) of the LED module, in particular the present temperature (T) itself, is determined, and a first and a second PWM control point are assigned to this temperature-dependent value, and the PWM values for producing the target color value are obtained through interpolation between the assigned PWM control points. This makes it possible to realize a precise color mixture in the LED module in a cost-effective way, with little computing power, despite temperature fluctuations (and possible electric current fluctuations).

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Dettingen, Germany

Rainer Kümer