Patent ID: 8638304

Claim:
A touch screen, comprising: an LCD panel; a display controller, for processing a video signal comprising a vertical synchronization signal and a horizontal synchronization signal to generate a panel control signal and a sensing control signal, with the panel control signal controlling the LCD panel so that the LCD panel displays a plurality of images according to the panel control signal, wherein each of the plurality of images is displayed in a plurality of scan lines according to the horizontal synchronization signal and a common voltage (Vcom) signal undergoes a digital transition between the display of each of the plurality of scan lines; a touch panel, for generating a sensing signal in response to a touch; and a sensing circuit, coupled to the touch panel and the display controller, for receiving the sensing signal and the sensing control signal to generate a position signal while the display controller is displaying the plurality of scan lines with reference to the sensing control signal, wherein the sensing circuit determines a plurality of sensing periods according to the sensing control signal and detects the sensing signal within the sensing periods, wherein each of the plurality of sensing periods includes a period of time needed to display at least two scan lines from the plurality of scan lines, and wherein the sensing circuit is configured to ignore the sensing signal during a predetermined sensing period of a frame corresponding to a time period during which variation of the common voltage (Vcom) signal supplied to the LCD panel is different from a plurality of other equally long sensing periods from the plurality of sensing periods of the frame, each of the other equally long sensing periods having an identical variation of the common voltage (Vcom) signal, and wherein the predetermined sensing period, which is ignored by the sensing circuit, includes a vertical blanking interval determined by the vertical synchronization signal.