Reducing common mode noise in touch applications
First Claim
1. A method comprising:
- performing a first scan of a first plurality of electrodes along a first axis in a capacitive sense array to obtain a first plurality of capacitance values corresponding to a mutual capacitance at electrode intersections of the capacitive sense array;
after performing the first scan, switching one or more of the first plurality of electrodes from receive electrodes of the first scan to transmit electrodes of a second scan;
performing the second scan of a second plurality of electrodes along a second axis in the capacitive sense array to obtain a second plurality of capacitance values corresponding to the mutual capacitance at the electrode intersections of the capacitive sense array;
combining at least a portion of the obtained first plurality of capacitance values with at least a portion of the obtained second plurality of capacitance values to obtain a third plurality of capacitance values without a subsequent scan of electrodes in the capacitive sense array, the combining counteracting effects of common mode noise in the obtained capacitance values;
identifying a first subset of the first plurality of capacitance values and a second subset of the second plurality of capacitance values based on a third subset of the third plurality of capacitance values; and
determining, by a processing device, a first coordinate of a conductive object proximate to the capacitive sense array based on the first subset and a second coordinate of the conductive object based on the second subset.
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Accused Products
Abstract
A processing device performs a first scan of a first plurality of electrodes along a first axis in a capacitive sense array to generate a first plurality of capacitance values corresponding to a mutual capacitance at electrode intersections of the capacitive sense array. The processing device performs a second scan of a second plurality of electrodes along a second axis in the capacitive sense array to generate a second plurality of capacitance values corresponding to the mutual capacitance at the electrode intersections of the capacitive sense array. The processing device determines a first coordinate of a conductive object proximate to the capacitive sense array based on the a first subset of first plurality of signals and a second coordinate of the conductive object based on a second subset of the second plurality of signals.
28 Citations
20 Claims
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1. A method comprising:
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performing a first scan of a first plurality of electrodes along a first axis in a capacitive sense array to obtain a first plurality of capacitance values corresponding to a mutual capacitance at electrode intersections of the capacitive sense array; after performing the first scan, switching one or more of the first plurality of electrodes from receive electrodes of the first scan to transmit electrodes of a second scan; performing the second scan of a second plurality of electrodes along a second axis in the capacitive sense array to obtain a second plurality of capacitance values corresponding to the mutual capacitance at the electrode intersections of the capacitive sense array; combining at least a portion of the obtained first plurality of capacitance values with at least a portion of the obtained second plurality of capacitance values to obtain a third plurality of capacitance values without a subsequent scan of electrodes in the capacitive sense array, the combining counteracting effects of common mode noise in the obtained capacitance values; identifying a first subset of the first plurality of capacitance values and a second subset of the second plurality of capacitance values based on a third subset of the third plurality of capacitance values; and determining, by a processing device, a first coordinate of a conductive object proximate to the capacitive sense array based on the first subset and a second coordinate of the conductive object based on the second subset. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus comprising:
a processing device coupled to a capacitive sense array, the processing device configured to; perform a first scan of a first plurality of electrodes parallel to a first axis in the capacitive sense array to obtain a first plurality of capacitance values corresponding to a mutual capacitance at electrode intersections of the capacitive sense array; after the first scan, switch one or more of the first plurality of electrodes from receive electrodes of the first scan to transmit electrodes of a second scan; perform the second scan of a second plurality of electrodes parallel to a second axis in the capacitive sense array to obtain a second plurality of capacitance values corresponding to the mutual capacitance at the electrode intersections of the capacitive sense array; combine at least a portion of the obtained first plurality of capacitance values with at least a portion of the obtained second plurality of capacitance values to obtain a third plurality of capacitance values without a subsequent scan of electrodes in the capacitive sense array, the combining counteracting effects of common mode noise in the obtained capacitance values; identify a first subset of the first plurality of capacitance values and a second subset of the second plurality of capacitance values based a third subset of the third plurality of capacitance values; and determine a first coordinate of a conductive object proximate to the capacitive sense array based on the first subset and a second coordinate of the conductive object based on the second subset. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. An apparatus comprising:
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a touch-sensor device, the touch-sensor device comprising an array of capacitive sense elements, the array comprising a plurality of transmit electrodes and a plurality of receive electrodes; a transmit selection circuit coupled to the touch-sensor device, the transmit selection circuit to selectively apply a transmit signal to one or more of the transmit electrodes; a receive selection circuit coupled to the touch-sensor device, the receive selection circuit to selectively measure a signal from one or more of the receive electrodes, wherein the measured signal corresponds to a mutual capacitance value between a transmit electrode and a receive electrode; and a processing device coupled to the touch-sensor device, the processing device configured to; perform a first scan of a first plurality of electrodes aligned with a first axis in the capacitive sense array to measure a first plurality of capacitance values from the receive electrodes aligned with the first axis in the capacitive sense array; switch an orientation of the transmit and receive electrodes; perform a second scan of a second plurality of electrodes aligned with a second axis in the capacitive sense array to measure a second plurality of capacitance values from the receive electrodes aligned with the second axis in the capacitive sense array; combine at least a portion of the measured first plurality of capacitance values with at least a portion of the measured second plurality of capacitance values to obtain a third plurality of capacitance values without a subsequent scan of electrodes in the capacitive sense array, the combining counteracting effects of common mode noise in the measured capacitance values; identify a first subset of the first plurality of capacitance values and a second subset of the second plurality of capacitance values based on a third subset of the third plurality of capacitance values; and determine a first coordinate of a conductive object proximate to the capacitive sense array based on the first subset of the first plurality of capacitance values and a second coordinate of the conductive object based on the second subset of the second plurality of capacitance values. - View Dependent Claims (18, 19, 20)
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Specification