Method and apparatus to improve noise immunity of a touch sense array
First Claim
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1. A method comprising:
- interleaving between listening for a level of noise and performing a scan of a touch sense array, the listening for the level of noise comprising;
receiving a response signal, which is generated in an absence of the scan, at a capacitive sensing circuit from the touch sense array;
measuring a noise component of the response signal;
determining whether the level of noise is above a threshold; and
when a level of noise within a passband of the capacitive sensing circuit is greater than a threshold, changing at least one parameter of the capacitive sensing circuit to move the passband substantially outside the frequency spectrum of the noise component.
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Abstract
A method for improving noise immunity of capacitive sensing circuit associated with a touch sense array is disclosed. The capacitive sensing circuit receives a response signal from a touch sense array. The capacitive sensing circuit measures a noise component of the response signal. When a level of noise of the noise component within a passband of the capacitive sensing circuit is greater than a threshold, the capacitive sensing circuit changes at least one parameter of capacitive sensing circuit to move the passband substantially outside the frequency spectrum of the noise component.
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Citations
17 Claims
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1. A method comprising:
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interleaving between listening for a level of noise and performing a scan of a touch sense array, the listening for the level of noise comprising; receiving a response signal, which is generated in an absence of the scan, at a capacitive sensing circuit from the touch sense array; measuring a noise component of the response signal; determining whether the level of noise is above a threshold; and when a level of noise within a passband of the capacitive sensing circuit is greater than a threshold, changing at least one parameter of the capacitive sensing circuit to move the passband substantially outside the frequency spectrum of the noise component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A circuit comprising
a capacitive sensing circuit configured to: -
receive a response signal from a touch sense array, which is generated in an absence of a scan of the touch sense array; measure a noise component of the response signal; and when a level of noise of the noise component within a passband of the capacitive sensing circuit is greater than a threshold, change at least one parameter of capacitive sensing circuit to move the passband substantially outside the frequency spectrum of the noise component., wherein the capacitive sensing circuit comprises a circuit for forcing synchronization of a sensing frequency passband to cause the frequency spectrum of the noise component to substantially match the passband of the capacitive sensing circuit. - View Dependent Claims (13, 14, 15)
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16. A processing device, comprising:
a capacitive sensing circuit configured to; receive a first response signal from a touch sense array; and measure a noise component of the first response signal, when a level of noise of the noise component within the passband of the capacitive sensing circuit is greater than a threshold, change at least one parameter of capacitive sensing circuit to move the passband substantially outside the frequency spectrum of the noise component; and processing logic coupled to the capacitive sensing circuit and configured to detect a conductive object proximate to the touch sense array using a second response signal generated responsive to a scan of the touch sense array, wherein the processing logic is configured to interleave between listening to the level of noise and performing the scan. - View Dependent Claims (17)
Specification