Patent ID: 9380673
Filing Date: 2016-06-28
CPC Classification: G09G,H05B,Y02B

Claim Text:
1. An LED backlight source of liquid crystal display device, which comprises: a boost converter, for boosting the input DC voltage and outputting boosted DC voltage; a plurality of LED strings connected in parallel, each LED string comprising a plurality of LEDs strung in series and receiving the boosted DC voltage from the boost converter, in each of the plurality of LED strings, the plurality of LEDs strung in series being further connected to a fourth resistor in series; a plurality of constant-current drivers, for controlling the size of the current of each of the plurality of LED strings, each constant-current driver controlling the size of the current of at least an LED string and the first constant-current driver controlling the connection and/or disconnection of the boost converter; an under-voltage protection control circuit, for outputting under-voltage protection voltage to each of the constant-current drivers and each of the constant-current drivers determining whether to stop operating based on received under-voltage protection voltage, the under-voltage protection voltage outputted to the first constant-current driver being less than the under-voltage protection voltages outputted to the constant-current drivers other than the first constant-current driver of the plurality of constant-current drivers; wherein the constant-current driver further comprises a control module, for determining whether to stop operating based on the received under-voltage protection voltage outputted by the under-voltage protection control circuit, the control module of the first constant-current driver further controlling the connection and/or disconnection of the boost converter; and a detection module, for detecting the voltage over the two ends of the fourth resistor connected in series with any LED string of the plurality of LED strings controlled by the constant-current driver, and controlling the current of any LED string of the plurality of LED strings based on the feedback of the voltage over the two ends of the fourth resistor.