Patent ID: 7525780
Filing Date: 2009-04-28
Classification: G09G,H05B,Y02B

Abstract:
1. A liquid crystal television, comprising: a backlight for illuminating a liquid crystal panel to display an image; a main power supply circuit for rectifying an AC power into a DC power supply voltage; an inverter circuit for boosting the power supply voltage supplied from the main power supply circuit through a transformer and supplying power to the backlight; an inverter controlling integrated circuit (IC) for controlling a voltage boosted by the inverter circuit based on a backlight driving signal and causing, if the power supply voltage from the main power supply circuit is lower than a specified voltage, the inverter circuit to stop boosting a voltage; a protective circuit having a protective function of temporarily cutting off the backlight driving signal to redrive the inverter circuit when the power supply voltage becomes lower than the specified voltage to stop driving the inverter circuit; and a microcomputer for outputting the backlight driving signal to the inverter controlling IC, the inverter circuit including a power recovery circuit for temporarily cutting off the backlight driving signal output from the microcomputer when the power supply voltage of the main power supply circuit drops due to temporary blackout, based on a value of the power supply voltage from the main power supply circuit, and restarting supply of the backlight driving signal to the protective circuit when the value of the power supply voltage is increased up to the specified voltage or higher, the power recovery circuit including: a power supply voltage determining circuit for comparing the power supply voltage from the main power supply circuit with the specified voltage by use of a Zener diode, and outputting a determination current if the power supply voltage is equal to or higher than the specified voltage; a backlight driving signal cutoff circuit for outputting, if the determination current is not output, the power supply voltage from the main power supply circuit to a base of a second transistor by use of a resistor, and emitting the backlight driving signal from the microcomputer to a ground terminal connected to an emitter of the second transistor to cut off the backlight driving signal; and a switchover circuit for emitting, if the determination current is output to a base of a first transistor, a current based on the power supply voltage from the main power supply circuit to a ground terminal connected to an emitter of the first transistor to cut off supply of the power supply voltage to the base of the second transistor through the resistor to restart supply of the backlight driving signal to the protective circuit.