Patent ID: 8625038

Claim:
An active-matrix liquid crystal display device comprising: a plurality of scan lines configured for providing a scan voltage; a plurality of signal lines crossing the scan lines configured for providing a data signal; and a plurality of pixel circuit positioned the neighborhood of each of the cross points of scan lines and signal lines, each pixel circuit comprising: a first transistor comprising a gate connected to one of the scan lines, a source connected to one of the signal lines, and a drain; a second transistor comprising a gate connected to the drain of the first transistor, a source connected to the gate of the first transistor, and a drain connected to said liquid crystal; and a third transistor comprising a source connected to the drain of the second transistor, a gate configured for receiving a first voltage, and a drain configured for receiving a second voltage, wherein the second transistor provides the data signal to the second transistor on the basis of the scan voltage of the scan line, the second transistor provides a pixel voltage to the liquid crystal according to the received data signal, said liquid crystal displays images corresponding to the pixel voltage, a drain current of the second transistor is substantially constant even when the source-drain voltage of the first transistor is varied.