MUTUAL CAPACITANCE MEASUREMENT IN A MULTI-TOUCH INPUT DEVICE
First Claim
1. A method for determining multiple touch events in a multi-touch sensor system having a capacitance measurement unit, a pulse drive unit, and a touch sensor having a plurality of nodes and a plurality of electrodes comprising at least two sets of electrodes, the method comprising:
- connecting a first electrode in a first set of electrodes to the capacitance measurement unit;
driving, with the pulse drive unit, a voltage or current pulse onto a second electrode in a second set of electrodes;
measuring, with the capacitance measurement unit, the mutual capacitance at a node corresponding to the first and second electrodes; and
comparing the measured mutual capacitance at the node with a previously measured mutual capacitance corresponding to the node;
reporting that the node has been touched if there has been a deviation from the previously measured mutual capacitance.
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Accused Products
Abstract
Systems and methods for determining multiple touch events in a multi-touch sensor system are provided. The system may include a capacitance measurement unit, a pulse drive unit, and a touch sensor having a plurality of nodes and a plurality of electrodes comprising at least two sets of electrodes. The method may include connecting a first electrode in a first set to the capacitance measurement unit, the pulse drive unit driving a voltage or current pulse onto a second electrode in a second set of electrodes. The method may further include the capacitance measurement unit measuring the mutual capacitance at a node corresponding to the first and second electrodes. The method may include comparing the measured mutual capacitance at the node with a previously measured mutual capacitance for the node, and reporting that the node has been touched if there has been a deviation from the previously measured mutual capacitance.
57 Citations
22 Claims
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1. A method for determining multiple touch events in a multi-touch sensor system having a capacitance measurement unit, a pulse drive unit, and a touch sensor having a plurality of nodes and a plurality of electrodes comprising at least two sets of electrodes, the method comprising:
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connecting a first electrode in a first set of electrodes to the capacitance measurement unit; driving, with the pulse drive unit, a voltage or current pulse onto a second electrode in a second set of electrodes; measuring, with the capacitance measurement unit, the mutual capacitance at a node corresponding to the first and second electrodes; and comparing the measured mutual capacitance at the node with a previously measured mutual capacitance corresponding to the node; reporting that the node has been touched if there has been a deviation from the previously measured mutual capacitance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A system for detecting one or more touch events on a touch sensor, comprising:
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a touch sensor having a plurality of electrodes comprising at least a first and second set of electrodes, wherein a proximity between electrodes in different sets defines a plurality of nodes; a pulse drive circuit operable to provide a charging or discharging voltage or current to the plurality of electrodes; capacitance measuring means for measuring the mutual capacitance at each of the plurality of nodes; and reporting means for reporting a touched node based on the measured mutual capacitance of that node. - View Dependent Claims (14, 15, 16)
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17. A system for detecting one or more touch events on a touch sensor, comprising:
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a touch sensor having a plurality of nodes and a plurality of electrodes comprising at least a first and second set of electrodes; a touch controller having a pulse drive circuit selectably coupled to the plurality of electrodes, and a capacitance measurement unit selectably coupled to the plurality of electrodes; wherein the touch controller is operable to; measure the mutual capacitance at a node corresponding to a first electrode in the first set of electrodes and a second electrode in the second set of electrodes; compare the mutual capacitance at the node with a previously measured mutual capacitance corresponding to the node; and report that the node has been touched if there has been a deviation from the previously measured mutual capacitance. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification