Reducing background capacitance associated with a touch surface
First Claim
1. A processing system for reducing background capacitance associated with a touch surface, comprising:
- transmitter circuitry configured to drive a transmitter electrode of the touch surface with a waveform, wherein the waveform is periodic;
receiver circuitry configured to detect input in a sensing region of the touch surface based on a resulting signal from a receiver electrode of the touch surface; and
offset reduction circuitry connected to the receiver circuitry and configured to;
subtract, prior to completion of an integration period of the waveform, a first plurality of charge associated with background capacitance from the resulting signal using a capacitor,wherein the integration period is approximately 1/N of a cycle of the waveform driving the transmitter electrode,wherein N is a natural number, andwherein the resulting signal is integrated by the receiver circuitry during the integration period;
execute a first reload of the capacitor prior to completion of the integration period of the waveform; and
subtract, prior to completion of the integration period of the waveform, a second plurality of charge associated with background capacitance from the resulting signal using the capacitor after the first reload.
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Accused Products
Abstract
A processing system for reducing background capacitance associated with a touch surface. The processing system includes: transmitter circuitry that drives a transmitter electrode of the touch surface with a waveform; receiver circuitry that detects input in a sensing region of the touch surface based on a resulting signal from a receiver electrode of the touch surface; and offset reduction circuitry connected to the receiver circuitry that: subtracts, prior to completion of an integration period of the waveform, a first plurality of charge associated with background capacitance from the resulting signal using a capacitor; executes a first reload of the capacitor prior to completion of the integration period of the waveform; and subtracts, prior to completion of the integration period of the waveform, a second plurality of charge associated with background capacitance from the resulting signal using the capacitor after the first reload.
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Citations
20 Claims
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1. A processing system for reducing background capacitance associated with a touch surface, comprising:
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transmitter circuitry configured to drive a transmitter electrode of the touch surface with a waveform, wherein the waveform is periodic; receiver circuitry configured to detect input in a sensing region of the touch surface based on a resulting signal from a receiver electrode of the touch surface; and offset reduction circuitry connected to the receiver circuitry and configured to; subtract, prior to completion of an integration period of the waveform, a first plurality of charge associated with background capacitance from the resulting signal using a capacitor, wherein the integration period is approximately 1/N of a cycle of the waveform driving the transmitter electrode, wherein N is a natural number, and wherein the resulting signal is integrated by the receiver circuitry during the integration period; execute a first reload of the capacitor prior to completion of the integration period of the waveform; and subtract, prior to completion of the integration period of the waveform, a second plurality of charge associated with background capacitance from the resulting signal using the capacitor after the first reload. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for reducing background capacitance associated with a touch surface, comprising:
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driving a transmitter electrode of the touch surface with a waveform, wherein the waveform is periodic; integrating, by receiver circuitry, a resulting signal from a receiver electrode of the touch surface; subtracting, prior to completion of an integration period of the waveform, a first plurality of charge associated with background capacitance from the resulting signal using a capacitor, wherein the integration period is approximately 1/N of a cycle of the waveform driving the transmitter electrode, and wherein N is a natural number; executing a first reload of the capacitor prior to completion of the integration period of the waveform; subtracting, prior to completion of the integration period of the waveform, a second plurality of charge associated with background capacitance from the resulting signal using the capacitor after the first reload; and detecting input in a sensing region of the touch surface based on the resulting signal. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification