Patent ID: 8154532

Claim:
A liquid crystal display (LCD), comprising: (a) a panel having a display region and a peripheral region adjacent the display region, the panel having a plurality of pixels spatially arranged in the form of a matrix in the display region for displaying an image; (b) a first photosensor member formed in the display region for sensing a change of incident light caused by a touch on the display region, wherein the first photosensor member comprises at least one photo transistor having a gate, a source and a drain, and is characterized with a sensitivity for sensing the change of the incident light, wherein the sensitivity varies with an intensity of ambient light and a voltage difference, Vgs, between the gate and the source of the at least one photo transistor, such that for each intensity value of the ambient light, there is a corresponding value of the voltage difference Vgs for the first photosensor member to operate at an optimal sensitivity, wherein Vgs=(Vg−Vs), Vg and Vs being voltages respectively applied to the gate and the source of the at least one photo transistor; (c) a second photosensor member formed in the peripheral region for measuring the intensity of the ambient light and generating an ambient light sensing signal corresponding to the measured intensity of the ambient light; and (d) a lookup table (LUT) stored in a memory device, containing a number of intensity values of the ambient light, and corresponding values of the voltage difference Vgs for the first photosensor member to operate at the optimal sensitivity; and (e) a sensor controller electrically coupled to the first photosensor member and the second photosensor member and in communication with the memory device, adapted for receiving the ambient light sensing signal from the second photosensor member, looking up a value of the voltage difference Vgs corresponding to the received ambient light sensing signal from the LUT, and regulating the voltages Vg and Vs respectively applied to the gate and the source of the at least one photo transistor of the first photosensor member according to the looked-up value of the voltage difference Vgs, so as to operate the first photosensor member at the optimal sensitivity.