Sensor baseline compensation in a force-based touch device
First Claim
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.
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Accused Products
Abstract
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.
173 Citations
11 Claims
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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:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A device for baseline compensating a force sensor signal output by a force sensor in a force-based input device, the force sensor signal providing measurements of force transmitted to the force sensor by a touch force applied to the force-based input device, the device comprising:
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a first leaky peak detector configured to accept the force sensor signal and output a decaying maximum value; a second leaky peak detector configured to accept the force sensor signal and output a decaying minimum value; a first subtractor operatively coupled to the first leaky peak detector and the second leaky peak detector and configured to subtract the minimum value from the maximum value and output a range value; a comparator operatively coupled to the subtractor and configured to output an update enable signal when the range value is less than a predetermined activity threshold; a filter operatively coupled to the comparator and configured to accept the force sensor signal and produce a baseline estimate when the update enable signal is asserted, and configured to hold a previously determined baseline estimate when the enable signal is not asserted; and a second subtractor operatively coupled to the filter and configured to accept the force sensor signal and subtract the baseline estimate from the force sensor signal and output a conditioned signal. - View Dependent Claims (10, 11)
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Specification