Patent ID: 8911111

Claim:
An LED backlight system, which comprises: a power source module, for supplying power; an LED array, electrically connected to the power source, comprising a plurality of LED strings with common anode; wherein the LED backlight system further comprising: a master switch module, comprising a plurality of first switch transistors, each of the plurality of first switch transistors being serially connected respectively to corresponding LED string for receiving switch control PWM signal of LED string to control the on-and-off of each LED string; a current detection module, serially connected to current loop of LED string, for outputting a plurality of current feedback signals of LED strings; a current equalizer module, connected to current detection module, the current equalizer module comprising equalizer control unit and equalizer switch unit connected to the equalizer control unit; wherein equalizer switch unit further comprising a plurality of second switch transistors, each of the plurality of second switch transistors being disposed correspondingly to each of LED strings; equalizer control unit comprising a plurality of comparators, each of comparators being disposed correspondingly to each of LED strings; enabling terminals of the plurality of comparators receiving switch control PWM signals of LED strings, non-inverting inputs of comparators receiving same reference voltage signal, inverting inputs of comparators respectively receiving current feedback signal outputted by current detection module, output of each comparator outputting control signal for current equalization of LED string to control on-and-off of second switch transistor to control impedance of current loop of each LED string so as to control illumination of each LED string; and a current shunt module, connected in parallel with current equalizer module, wherein current shunt module comprising equal number of shunt resistors as number of LED strings, first end of each of shunt resistors being connected in parallel with drain terminal of second switch transistor of corresponding LED string, second end of each of shunt resistors being connected in parallel with source terminal of second switch transistor corresponding to each LED string for performing current shunt on current equalizer module.