Koninklijke Philips Corporation N.v.

U.S. Philips Corporation

Alexander Christiaan De Rijck

Roel Van Woudenberg

Peter Hubertus Franciscus Deurenberg

Henricus Marie Peeters

Hendrik Huisman

The invention relates to a power semiconductor device () cooling assembly for cooling a power semiconductor device (), wherein the assembly comprises an actively cooled heat sink () and a controller (), wherein the controller () is adapted for adjusting the cooling efficiency of the heat sink () depending on the temperature of the high current carrying semiconductor junction comprised in the power semiconductor device ().

Power semiconductor device adaptive cooling assembly

The present invention relates to a method for determining drive values for driving a lighting device at a desired brightness and color. The method comprising the steps of determining a first luminous flux weight ratio based on the desired color and a first drive current for driving each of the differently colored LEDs, determining a first luminous flux for each of the differently colored LEDs based on the desired brightness and the first luminous flux weight ratio, comparing, for each of the differently colored LEDs, the first luminous flux with a nominal luminous flux for a plurality of different drive currents, selecting, for each of the differently colored LEDs, a preferred drive current that at least can produce the first luminous flux, determining a second luminous flux weight ratio based on the desired color and the selected drive currents for each of the differently colored LEDs, determining a second luminous flux for each of the differently colored LEDs based on the desired brightness and the second luminous flux weight ratio, and determining a duty cycle for each of the differently colored LEDs at the selected drive currents, wherein the selected currents at the determined duty cycles produces the second luminous flux for each of the differently colored LEDs. The present invention provides for the possibility to limit the number of necessary computational steps for determining preferred drive currents. Furthermore, an increase in number of current level and/or differently colored LEDs would only slightly increase the computational cost.

Method and driver for determining drive values for driving a lighting device

An optical transmitter comprising a control loop for stabilizing the bias current which sets a bias level of the amount of light emitted by a laser diode 6. A cascade circuit 5 which includes the laser diode 6, a photodiode 7 and a variable gain control amplifier 8 is connected in the negative feedback path of the control loop. To prevent amplitude modulation of the bias current when a modulation signal occurs at the input of the gain control amplifier, the control loop produces a cancelling signal of a magnitude which cancels the mean value of such modulation signal. The cancelling signal is derived from the modulation signal in a fixed manner, by fixing the transfer factor of the negative feedback path as measured by transmission of an auxiliary signal through such path and adjusting the gain of amplifier 8 in accordance with the result of such measurements.

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Eindhoven, Netherlands

Alexander Christiaan De Rijck