Patent ID: 8841861
Filing Date: 2014-09-23
Classification: H05B,Y02B

Abstract:
1. A dimming device for a lighting device including a main light emitting unit and a secondary light emitting unit, the secondary light emitting unit including at least one red-light-emitting element, at least one green-light-emitting element and at least one blue-light-emitting element, said dimming device comprising: a constant current generator adapted for outputting a current with a fixed amplitude to the main light emitting unit; a state generator operable to repeatedly count based on an input frequency signal so as to generate a state counting output having a counting value that is equal to one of a plurality of continuous values and that changes from a current one of the continuous values to a previous one of the continuous values after a time period associated with the input frequency signal, the values being respectively associated with a plurality of different light-mixing states of the secondary light emitting unit; and an RGB modulation circuit connected electrically to said state generator for receiving the state counting output therefrom, and operable to generate, based on the state counting output from said state generator, a plurality of periodic pulse width modulation (PWM) signals with the same PWM cycle, each of the PWM signals being adapted to drive a corresponding one of the red-light-emitting, green-light-emitting and blue-light-emitting elements of the secondary light emitting unit such that the secondary light-emitting unit is sequentially operated in the different light-mixing states; wherein the secondary light-emitting unit emits a mixed light with an individual color in each of the different light-mixing states to compensate lighting of the main light emitting unit.