Patent ID: 7337085
Filing Date: 2008-02-26
Classification: G06F

Abstract:
1. A method of compensating a force sensor signal for baseline error, the force sensor signal being output by a force sensor in a force-based input device, the force sensor signal being used to determine a touch location on the force-based input device, the method comprising: subtracting a baseline estimate from the force sensor signal to obtain a corrected force sensor signal; determining a decaying maximum value of the corrected force sensor signal, wherein the decaying maximum value is reset to a current value of the corrected force sensor signal when the current value of the corrected force sensor signal is greater than the decaying maximum value; determining a decaying minimum value of the corrected force sensor signal, wherein the decaying minimum value is reset to a current value of the corrected force sensor signal when the corrected force sensor signal is less than the decaying minimum value; subtracting the decaying minimum value from the decaying maximum value to form a range value; updating the baseline estimate by holding the baseline estimate when the range is greater than a predefined activity threshold and updating the baseline estimate based on the force sensor signal when the range value is less than the first predefined activity threshold; and outputting the corrected force sensor signal.