Liquid crystal display apparatus and LED backlight module thereof

摘要

A liquid crystal display apparatus includes an LED backlight module incorporated therein, and the LED backlight module includes a boosting circuit for receiving a direct current voltage, boosting the direct current voltage, and then outputting a step-up direct current voltage; an LED string, including a plurality of LEDs connected in series, for receiving the step-up direct current voltage from the boosting circuit; a constant current driver circuit for generating a signal used for controlling the boosting circuit; and a amplified circuit for receiving the direct current voltage, magnifying the signal from the constant current driver circuit, and then outputting a magnified signal to the boosting circuit. The power consumption of the boosting circuit is reduced by adding the amplified circuit for amplifying a driving voltage to the boosting circuit. Furthermore, the driving voltage input to the MOS transistor of the boosting circuit is amplified by the amplified circuit, and thereby the value of the DCR value of the MOS transistor is reduced. The power consumption of the MOS transistor is reduced, and the temperature is lowered, so the lifespan of the MOS transistor is extended.

主权项

1. An LED backlight module, used for a liquid crystal display apparatus, comprising:
a boosting circuit for receiving a direct current voltage, boosting the direct current voltage, and then outputting a step-up direct current voltage; an LED string, including a sixth resistor and a plurality of LEDs connected in series, for receiving the step-up direct current voltage from the boosting circuit; a constant current driver circuit for generating a signal used for controlling the boosting circuit; a amplifying circuit for receiving the direct current voltage, amplifying the signal from the constant current driver circuit, and then outputting a magnified signal to the boosting circuit; wherein the amplifying circuit includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a first transistor, and a second transistor; wherein a first end of the first resistor connects to a first end of the third resistor and receives the direct current voltage; wherein a second end of the first resistor connects to the boosting circuit; wherein a second end of the third resistor connects to a collector of the first transistor; wherein a base of the first transistor connects to one end of the fifth resistor and the constant current driver circuit; wherein the other end of the fifth resistor connects to an emitter of the first transistor and electrically grounds; wherein a base of the second transistor connects to one end of the fourth resistor and the collector of the first transistor; wherein a collector of the second transistor connects to one end of the second resistor and the second end of the first resistor; wherein an emitter of the second transistor connects to the other end of the second resistor and the other end of the fourth resistor; and wherein the other end of the fourth resistor electrically grounds.