Analog elimination of ungrounded conductive objects in capacitive sensing
AssigneeMicrochip Technology Incorporated
InventorsBurke Davison, Xiang Gao, Yann LeFaou
Life of this patent
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Abstract
In a method for performing a touch determination with a capacitive sensor, a self capacitance measurement of a capacitive sensor is initiated, wherein at the same time a mutual capacitance measurement including the capacitive sensor is performed. Such a method can be performed such that the self capacitance measurement and the mutual capacitance measurement differentially cancel with ungrounded conductive objects approaching or touching the capacitive sensor and additively combine for grounded objects approaching or touching the capacitive sensor.
Claims11
A method for performing a touch determination with a capacitive sensor, comprising:
- performing a calibration method, wherein the calibration method is performed before performing the touch determination, the calibration method comprising:
- performing an individual self capacitance measurement and storing a first measurement value;
- performing an individual mutual capacitance measurement and storing a second measurement value;
- and
- calculating a scale factor from said first and second measurement values;
- initiating a self capacitance measurement of a capacitive sensor, wherein at the same time a mutual capacitance measurement including the capacitive sensor is performed;
- and
- applying said scale factor to said self capacitance or said mutual capacitance measurement.
A method for performing a touch determination with a capacitive sensor, comprising:
- performing a calibration method to determine a scaling factor, wherein the calibration method is performed before performing the touch determination, the calibration method comprising:
- performing an individual self capacitance measurement and storing a first measurement value;
- performing an individual mutual capacitance measurement and storing a second measurement value;
- and
- calculating a scaling factor from said first and second measurement values;
- initiating a self capacitance measurement of a capacitive sensor,
- initiating a mutual capacitance measurement including the capacitive sensor;
- performing a scaling of either an output value of the self capacitance measurement or the mutual capacitance measurement;
- and
- combining the output values of the self capacitance measurement and the mutual capacitance measurement.
A method for performing a touch determination with a capacitive sensor, comprising:
- performing a calibration method, wherein the calibration method is performed before performing the touch determination, the calibration method comprising:
- performing an individual self capacitance measurement and storing a first measurement value;
- performing an individual mutual capacitance measurement and storing a second measurement value;
- and
- calculating a scale factor from said first and second measurement values;
- initiating a self capacitance measurement of a capacitive sensor, wherein at the same time a mutual capacitance measurement including the capacitive sensor is performed such that the self capacitance measurement and the mutual capacitance measurement differentially cancel with ungrounded conductive objects approaching or touching said capacitive sensor and additively combine for grounded objects approaching or touching said capacitive sensor;
- and
- applying said scale factor to said self capacitance or said mutual capacitance measurement.
Dependencies are inferred from the claim text.