Interference detection using frequency modulation
First Claim
1. A processing system, comprising:
- a sensor module having sensor module circuitry configured to couple to a plurality of sensor electrodes, the sensor module circuitry is configured to;
operate, during a first time period, the plurality of sensor electrodes in a capacitive sensing mode to perform capacitive sensing using a plurality of sensing bursts,operate, during a second time period, the plurality of sensor electrodes in an interference detection mode to detect interfering signals using at least first and second interference bursts, wherein a frequency of the first interference burst is different than a frequency of the second interference burst, andwherein the first time period and the second time period are non-contiguous time periods separated by an intermediate time period such that a phase of the plurality of sensing bursts is offset from a phase of at least one of the first and second interference bursts, andwherein each of the first and second interference bursts comprises a reset stage, an integrate stage, and a third stage, wherein the sensor module circuitry is configured to adjust lengths of the third stages in order to set the frequencies of the first and second interference bursts.
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Abstract
This disclosure generally provides embodiments to reduce the likelihood that an input device fails to detect an interfering signal when performing interference detection using interference bursts that are phase offset from sensor bursts used to perform capacitive sensing. In one embodiment, the input device adjusts the frequency of the interference bursts instead of using interference bursts with the same frequency. Doing so adjusts the phases of the interference bursts relative to each other such that even if one of the interference bursts is aligned with the interfering signal in a manner that the signal is not detected, an interference burst with a different frequency has a different alignment relative to the interfering signal. The measurements acquired by the differently aligned interference burst can be used to detect the presence of the interfering signal.
12 Citations
19 Claims
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1. A processing system, comprising:
a sensor module having sensor module circuitry configured to couple to a plurality of sensor electrodes, the sensor module circuitry is configured to; operate, during a first time period, the plurality of sensor electrodes in a capacitive sensing mode to perform capacitive sensing using a plurality of sensing bursts, operate, during a second time period, the plurality of sensor electrodes in an interference detection mode to detect interfering signals using at least first and second interference bursts, wherein a frequency of the first interference burst is different than a frequency of the second interference burst, and wherein the first time period and the second time period are non-contiguous time periods separated by an intermediate time period such that a phase of the plurality of sensing bursts is offset from a phase of at least one of the first and second interference bursts, and wherein each of the first and second interference bursts comprises a reset stage, an integrate stage, and a third stage, wherein the sensor module circuitry is configured to adjust lengths of the third stages in order to set the frequencies of the first and second interference bursts. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An integrated circuit, comprising:
a processing system configured to; operate, during a first time period, a plurality of sensor electrodes in a capacitive sensing mode to perform capacitive sensing using a plurality of sensing bursts, operate, during a second time period, the plurality of sensor electrodes in an interference detection mode to detect interfering signals using at least first and second interference bursts, wherein a frequency of the first interference burst is different than a frequency of the second interference burst, and wherein the first time period and the second time period are non-contiguous time periods separated by an intermediate time period such that a phase of the plurality of sensing bursts is offset from a phase of at least one of the first and second interference bursts, and wherein the first and second interference bursts each comprises a reset stage, an integrate stage, and a third stage, wherein the processing system is configured to adjust lengths of the third stages in order to set the frequencies of the first and second interference bursts. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A method, comprising:
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operating, during a first time period, a plurality of sensor electrodes in a capacitive sensing mode to perform capacitive sensing using a plurality of sensing bursts; operating, during a second time period, the plurality of sensor electrodes in an interference detection mode to detect interfering signals using at least first and second interference bursts, wherein a frequency of the first interference burst is different than a frequency of the second interference burst and each of the first and second interference bursts comprises a reset stage, an integrate stage, and a third stage; adjusting lengths of the third stages of the first and second interference bursts in order to set the frequencies of the first and second interference bursts, wherein the first time period and the second time period are non-contiguous time periods separated by an intermediate time period such that a phase of the plurality of sensing bursts is offset from a phase of at least one of the first and second interference bursts. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification