Contact identification and tracking on a capacitance sensing array
First Claim
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1. A capacitance sensing apparatus comprising:
- a first plurality of electrodes disposed along a first axis;
a second plurality of electrodes disposed along a second axis;
a capacitance sensing circuit coupled to the first and second pluralities of electrodes and configured to measure a plurality of capacitances representative of a conductive object proximate to the first and second pluralities of electrodes; and
a processor coupled to the capacitance sensing circuit and configured to calculate a position of at least one contact on the first and second pluralities of electrodes based on the measured capacitances, the processor configured to calculate a position based on at least one virtual node, wherein the at least one virtual node is generated to complete an N×
M matrix of nodes and is populated by mirroring capacitance data from a real node along a meridian, the meridian on at least one axis centered on the peak intersection.
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Abstract
A technique for providing reliable position calculations for conductive inputs at the edges of a touch-sensitive array is disclosed. A matrix of sensors is completed using virtual sensors or nodes, allowing for a closer approximation of position of a conductive object. The matrix may be defined by a center point or sensor and a number of surrounding nodes or sensors.
53 Citations
23 Claims
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1. A capacitance sensing apparatus comprising:
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a first plurality of electrodes disposed along a first axis; a second plurality of electrodes disposed along a second axis; a capacitance sensing circuit coupled to the first and second pluralities of electrodes and configured to measure a plurality of capacitances representative of a conductive object proximate to the first and second pluralities of electrodes; and a processor coupled to the capacitance sensing circuit and configured to calculate a position of at least one contact on the first and second pluralities of electrodes based on the measured capacitances, the processor configured to calculate a position based on at least one virtual node, wherein the at least one virtual node is generated to complete an N×
M matrix of nodes and is populated by mirroring capacitance data from a real node along a meridian, the meridian on at least one axis centered on the peak intersection. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system comprising:
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a capacitance sensing array comprising; a first plurality of electrodes disposed along a first axis; a second plurality of electrodes disposed along a second axis; a capacitance sensing circuit coupled to the first and second pluralities of electrodes and configured to measure a plurality of capacitances formed at the intersections of the first and second pluralities of electrodes; and a processor coupled to the capacitance sensing circuit and configured to calculate a position of at least one contact on the first and second pluralities of electrodes based on the measured capacitances, the processor configured to generate virtual values for intersections to complete an N×
M matrix of intersections that are not present on the array but necessary for the calculation of the position of the at least one contact, wherein the virtual values for intersections that are not present on the array are populated by mirroring real values for intersections that are present on the array along a meridian defined on at least one axis centered on a peak intersection. - View Dependent Claims (12, 13, 14, 15)
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16. A method for determining position of a capacitance sensing array comprising:
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scanning the capacitance sensing array, the capacitance sensing array comprising a first plurality of electrodes disposed along a first axis and a second plurality of electrodes disposed along a second axis; building an array of values corresponding to intersections of the first and second pluralities of electrodes; identifying at least one peak intersection, wherein the peak intersection is characterized by a greater measured capacitance than any of the surrounding intersections; determining if the peak intersection is in a location when a complete N×
M matrix may be generated about the peak intersection;if an N×
M matrix may be generated, generating the N×
M matrix and calculating the position of the at least one contact on the array; andif an N×
M matrix may not be generated,defining a meridian on at least one axis centered on the peak intersection; generating dummy intersections to complete the N×
M matrix;populating the dummy intersections by mirroring capacitance values about the meridian; and calculating the position of the at least one contact on the array. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23)
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Specification