Patent ID: 8242706

Claim:
A drive system for an illumination device, comprising: a plurality of light-emitting diodes (LEDs); an extra load; an illumination setting unit, for providing an illumination parameter, wherein the illumination parameter comprises a work cycle; a power supply unit, for providing a direct current (DC); a microprocessor, for receiving the illumination parameter and generating a plurality of pulse width modulation (PWM) signals including a plurality of drive signals and a compensation signal according to the received illumination parameter, wherein the plurality of drive signals correspond to the plurality of LEDs respectively; a plurality of first drive units corresponding to the plurality of LEDs and the plurality of drive signals respectively, wherein each of the first drive units receives one of the plurality of drive signals to drive corresponding one of the plurality of LEDs respectively, where the corresponding LED receives the DC for illumination; and a second drive unit, for receiving the compensation signal and outputting the DC to the extra load according to the compensation signal; wherein each of the plurality of drive signals has a high-level cycle, a low-level cycle and a whole cycle, a ratio of the high-level cycle to the whole cycle is equal to the work cycle, a starting time point of the high-level cycle of one of the plurality of drive signals and a starting time point of the high-level cycle of another one of the plurality of drive signals are spaced apart for a time period of the low-level cycle of the another one drive signal, a high-level sum is a summation of all the plurality of drive signals at each time point during the whole cycle thereof, a highest level value is a maximum value of the high-level sums during the whole cycle, and the compensation signal is a signal for compensating each of the high-level sums to the highest level value at each time point during the whole cycle.