Patent ID: 7542021

Claim:
A common voltage compensating circuit for a liquid crystal display device, comprising: a voltage distributing unit outputting a reference voltage; a deviation sensing unit detecting a deviation of a common voltage in a liquid crystal panel and outputting a deviation signal corresponding to the deviation of the common voltage; and a first compensating unit coupled with the voltage distributing unit and the deviation sensing unit, wherein the first compensating unit compensates the common voltage by outputting a first compensated common voltage based on the reference voltage, the deviation signal and a feedback input of the first compensated common voltage, wherein the deviation sensing unit detects the deviation of the common voltage from one of an anterior dummy common line, a posterior dummy common line and a dummy gate line in the liquid crystal panel, and wherein the deviation sensing unit includes a direct current (DC) source and a resistor connected to the one of the anterior dummy common line, the posterior dummy common line and the dummy gate line.