Guard electrodes in a sensing stack
First Claim
1. A capacitive sensing device, comprising:
- a first layer in a sensing stack, the first layer comprising an electrically floating electrode and a first guard electrode, wherein the first guard electrode surrounds the floating electrode, and wherein the floating electrode is not connected to any routing traces;
a second layer in the sensing stack ohmically insulated from the first layer, the second layer comprising a sensor electrode coupled to a routing trace, wherein the floating electrode at least partially overlaps the sensor electrode in the sensing stack, and the first guard electrode at least partially overlaps the routing trace in the sensing stack; and
a processing system coupled to the sensor electrode via the routing trace, the processing system is configured to;
drive sensing signals onto the routing trace for performing capacitive sensing; and
drive a guarding signal onto the first guard electrode which mitigates capacitive coupling between the routing trace and other components in the capacitive sensing device.
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Abstract
This disclosure generally provides an input device that includes a multi-layered capacitive sensor which includes a first layer disposed over a second layer that contains a plurality of sensor electrodes coupled to respective traces. The first and second layers form a capacitive sensing stack where the first layer is between the second layer and a touch surface for interacting with the input object. The first and second layers may be disposed on either the same substrate or different substrates in the stack. In one embodiment, the first layer includes electrically floating electrodes and at least one guard electrode. These components may align with respective components in the second layer. For example, the electrically floating electrodes in the first layer may at least partially cover the sensor electrodes in the second layer.
230 Citations
21 Claims
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1. A capacitive sensing device, comprising:
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a first layer in a sensing stack, the first layer comprising an electrically floating electrode and a first guard electrode, wherein the first guard electrode surrounds the floating electrode, and wherein the floating electrode is not connected to any routing traces; a second layer in the sensing stack ohmically insulated from the first layer, the second layer comprising a sensor electrode coupled to a routing trace, wherein the floating electrode at least partially overlaps the sensor electrode in the sensing stack, and the first guard electrode at least partially overlaps the routing trace in the sensing stack; and a processing system coupled to the sensor electrode via the routing trace, the processing system is configured to; drive sensing signals onto the routing trace for performing capacitive sensing; and drive a guarding signal onto the first guard electrode which mitigates capacitive coupling between the routing trace and other components in the capacitive sensing device. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 21)
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11. A capacitive sensing stack, comprising
a first layer comprising an electrically floating electrode and a first guard electrode, wherein the first guard electrode surrounds the floating electrode, and wherein the floating electrode is not connected to any routing traces; -
a second layer ohmically insulated from the first layer, the second layer comprising a sensor electrode coupled to a routing trace, wherein the floating electrode at least partially overlaps the sensor electrode in the capacitive sensing stack, and the first guard electrode at least partially overlaps the routing trace in the capacitive sensing stack; a protective cover providing a touch surface, wherein the first layer is between the protective cover and the second layer; and a processing system configured to drive a guarding signal onto the first guard electrode which mitigates capacitive coupling between the routing trace and other components in a capacitive sensing device. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method, comprising:
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disposing a first layer onto a first surface, wherein the first layer comprises a plurality of electrically floating electrodes and a first guard electrode, wherein the first guard electrode surrounds the plurality of electrically floating electrodes, and wherein the plurality of electrically floating electrodes are not connected to any routing traces; disposing a second layer onto a second, different surface, wherein the second layer comprises a plurality of sensor electrodes each coupled to a respective routing trace; forming a capacitive sensing stack comprising the first and second layers, wherein each of the plurality of electrically floating electrodes at least partially overlaps a corresponding one of the sensor electrodes in the capacitive sensing stack, and the first guard electrode at least partially overlaps a first routing trace of the routing traces in the capacitive sensing stack, wherein the first guard electrode is configured to, when driven using a guarding signal, mitigate capacitive coupling between the first routing trace and other components in a capacitive sensing device; and disposing a protective cover onto the capacitive sensing stack such that the first layer is between the protective cover and the second layer, wherein the protective cover comprises a touch surface. - View Dependent Claims (18, 19, 20)
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Specification