Patent ID: 8411009

Claim:
A liquid crystal display device comprising: an array substrate and a counter substrate facing each other; a liquid crystal layer interposed between the array substrate and the counter substrate; a display area formed of the array substrate, the counter substrate and the liquid crystal layer and including a plurality of pixels arranged in a matrix; a driving unit to drive the plurality of pixels connected to signal lines and scan lines arranged in a matrix; a pixel electrode provided to each pixel; a common electrode formed on the counter substrate and facing the pixel electrode; an auxiliary capacitance provided to each pixel to interpose an auxiliary capacitance signal to the pixel electrode; and auxiliary capacitance lines arranged along the pixels in a row direction and connected to the auxiliary capacitance of the pixel; wherein the driving unit includes an auxiliary capacitance line driving circuit to supply a first voltage, a second voltage smaller than the first voltage and a third voltage smaller than the second voltage to the auxiliary capacitance lines, and the voltage difference between the first voltage and the second voltage is smaller than that between the second voltage and the third voltage; wherein the pixel includes a pixel switch connected to the pixel electrode, the pixel switch including a gate electrode connected to the scan line, a source electrode connected to the signal line and a drain electrode connected to the pixel electrode; wherein an image signal is written into the pixel electrode through the pixel switch and a common voltage is supplied to the common electrode; wherein the common voltage corresponds to respective center voltages of the image signal and a voltage applied to the liquid crystal layer; wherein the voltage values are given so as to satisfy a following expression: ( V 2−( V 1 +V 3)/2)× Cst/Ctot=ΔVg ×( Cgd/Ctot ), wherein, V 1 , V 2 and V 3 are first, second and third voltages, respectively; Cst is an auxiliary capacitance value; Cgd is a capacitance value generated between the gate electrode and the drain electrode when the pixel switch is “OFF”; Ctot is sum of a liquid crystal capacitance, an auxiliary capacitance value Cst, a capacitance generated between the source electrode and the drain electrode and the capacitance value Cgd; ΔVg is voltage difference between “ON” voltage and “OFF” voltage of the pixel switch.