COMMON VOLTAGE MODULATION CIRCUIT FOR LIQUID CRYSTAL DISPLAY DEVICE, ESPECIALLY REDUCING VARIABLE WIDTH OF COMMON VOLTAGE TO MATCH FLICKER LEVEL

摘要

PURPOSE: A common voltage modulation circuit for a liquid crystal display device is provided to match the flicker level by adjusting the variable width of the common voltage to 10mV¯20mV. CONSTITUTION: A common voltage modulation circuit for use in a liquid crystal display device includes a duty ratio controller(41), an RC circuit, a controller and an amplifier(42). The RC circuit generates the sawtooth wave generated at the sawtooth generator and the pulse width modulation(PWM) pulse through a comparator by receiving the DC voltage as an input to be controlled in firmware. The RC circuit converts the pulse outputted from the duty cycle controller into the direct voltage. The controller receives the direct voltage outputted from the output terminal of the RC circuit to modulate. And, the amplifier receives the output signal of the controller to the non-inverting terminal and outputs the common voltage through the output terminal connected to the non-inverting terminal.