Mitigation of parasitic capacitance
First Claim
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1. A method of reducing an effect of parasitic capacitance on a touch input device, the method comprising:
- generating a plurality of periodic signals different from a touch sense circuitry output signal, the plurality of periodic signals having a same frequency as the touch sense circuitry output signal;
initializing a gain of the plurality of periodic signals;
combining the plurality of periodic signals with the touch sense circuitry output signal; and
adjusting the gain of the plurality of periodic signals until the combination of the plurality of periodic signals and the touch sense circuitry output signal is approximately zero.
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Abstract
A touch sensor panel configured to mitigate the effect of parasitic capacitance on the ability of a capacitive touch sensor panel to reliably detect touch and proximity events. The touch sensor panel includes circuitry that can electrically drive a set of conductive shields that partially encapsulate various conductive components of the touch sensor panel. The touch sensor panel can also include circuitry that work to calibrate the touch sensor panel against variations in signal phase due to a parasitic capacitance.
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Citations
23 Claims
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1. A method of reducing an effect of parasitic capacitance on a touch input device, the method comprising:
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generating a plurality of periodic signals different from a touch sense circuitry output signal, the plurality of periodic signals having a same frequency as the touch sense circuitry output signal; initializing a gain of the plurality of periodic signals; combining the plurality of periodic signals with the touch sense circuitry output signal; and adjusting the gain of the plurality of periodic signals until the combination of the plurality of periodic signals and the touch sense circuitry output signal is approximately zero. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An apparatus for reducing an effect of parasitic capacitance on a touch input device, the apparatus comprising:
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a plurality of signal generators configured to generate a plurality of periodic signals different from an output of touch sensor circuitry; a signal combiner configured to combine the plurality of periodic signals with the output of the touch sensor circuitry; and a processor capable of determining an output of the signal combiner and adjusting a gain of the plurality of periodic signals if the output of the signal combiner is above a pre-determined threshold. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A non-transitory computer readable storage medium having stored thereon a set of instructions for detecting proximity events in a touch sensor panel, that when executed by a processor causes the processor to:
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determine a frequency of a touch sense circuitry output signal; generate a plurality of signals different from the touch sense circuitry output signal, the plurality of signals having the same frequency as the determined frequency of the touch sense circuitry output signal; combine the plurality of signals with the touch sense circuitry output signal; determine if a magnitude of the combination is below a pre-determined threshold; and adjust a gain of the signals until the combination is below a pre-determined threshold. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A computing device including an apparatus for reducing an effect of parasitic capacitance on a touch input device, the apparatus comprising:
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a plurality of signal generators configured to generate a plurality of periodic signals different from an output of touch sensor circuitry; a signal combiner configured to combine the plurality of periodic signals with the output of the touch sensor circuitry; and a processor capable of determining an output of the signal combiner and adjusting a gain of the plurality of periodic signals if the output of the signal combiner is above a pre-determined threshold.
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Specification