| CPC G06F 3/0446 (2019.05) [G06F 3/0418 (2013.01)] | 22 Claims |
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1. A method of reading a touch sensor having columns and rows forming a row-column grid, the method comprising:
applying a set of column input signals simultaneously to respective column inputs of the touch sensor, each column input signal being an analog signal at a respective frequency;
combining column output signals taken from respective column outputs of the touch sensor to form a combined column signal, each column output signal corresponding to a respective one of the column input signals but altered in amplitude in dependence on whether the touch sensor is being touched in a vertical screen region corresponding to the respective column of the touch sensor;
applying a set of row input signals simultaneously to respective row inputs of the touch sensor, each row input signal being an analog signal at a respective frequency;
combining row output signals taken from respective row outputs of the touch sensor to form a combined row signal, each row output signal corresponding to a respective one of the row input signals but altered in amplitude in dependence on whether the touch sensor is being touched in a horizontal screen region corresponding to the respective row of the touch sensor;
performing a frequency-domain transform on digitized samples of the combined column signal and on digitized samples of the combined row signal, to obtain, respectively, a set of column values that depend on the amplitudes of the column output signals in the combined column signal, and a set of row values that depend on the amplitudes of the row output signals in the combined row signal; and
detecting a touch input to the touch sensor by evaluating the column values and the row values.
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