US Patent 7337085 Sensor baseline compensation in a force-based touch device

Disclosed is method and device for compensating a force sensor signal for baseline error in a force-based touch screen. In one embodiment, baseline compensation includes determining a decaying maximum value and a decaying minimum value of the force sensor signal, and subtracting these values to obtain a range value. When the range value is less than a predetermined activity threshold, updating of the baseline is disabled. The decaying maximum value and decaying minimum value are reset to the current value of the force sensor signal when exceeded by the current value of the force sensor signal.