Patent ID: 9007335
Filing Date: 2015-04-14
Classification: G06F,G09G

Abstract:
1. A method of projected capacitance touch sensing on a display screen, the method comprising: updating said display screen by applying a drive waveform to each pixel of the display screen over a plurality of frame periods, wherein a said drive waveform for a pixel defines a transition of the pixel from a current pixel state to an updated pixel state over said plurality of frame periods, and wherein said updating comprises selecting each row of said display screen in turn for a row driving period and driving columns of the display screen with a time slice of drive waveforms for pixels of the row to perform a frame update of said display screen, and repeating said frame update to drive pixels of said display screen with a plurality of successive time slices of said drive waveforms to drive said pixels with said drive waveforms; sensing a signal from a projected capacitance touch sensing electrode of said display screen during a sensing interval and using said sensing to provide a touch sensing response; calculating a change value for each selected row which indicates the change between column drive levels of said drive waveforms for pixels of each selected row and a row which will be selected next in turn during said updating step; generating a column drive row change signal when said change value is greater than a threshold value; and inhibiting said touch sensing responsive to said generation of said column drive row change signal during said sensing interval.