Switching device for driving LED array by pulse-shaped current modulation
AssigneeKoninklijke Philips Electronics N.V.
InventorJohannes Hendrik Wessels
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Abstract
A circuit drives an LED array and controls the brightness of the LED array by regulating the current flowing through the array. The LED array is driven by a pulse-shaped current of which the mean value is regulated with at least one or two of the following types of modulation: frequency modulation, pulse-width modulation, and amplitude modulation.
Claims2
A switching device for driving an LED array, wherein the switching device comprises means for driving the LED array with a pulse-shaped current of mean strength and for regulating the mean strength of the pulse-shaped current flowing through the LED array by modulation means for modulating the pulse-shaped current with frequency modulation, pulse-width modulation, and amplitude modulation, wherein the mean strength has a nominal strength Inom and wherein, from Inom down to 0.05 Inom, the mean strength is regulated by means of the pulse-width modulation, and for less than 0.05 Inom, the mean strength is regulated by superimposing the pulse-width modulation on the amplitude modulation.
Dependencies are inferred from the claim text.