Front-end signal compensation
First Claim
Patent Images
1. A touch surface device, comprising:
- a touch-sensitive panel having a sense node configured for providing an output signal indicative of a touch or no-touch condition on the panel, the output signal including a static portion unaffected by a touch and a dynamic portion affected by the touch;
a compensation circuit, coupled to the sense node, configured for generating a compensation signal that when summed with the output signal prior to demodulation of the output signal substantially removes the static portion of the output signal so as to generate a compensated output signal; and
a sensing circuit coupled to the compensation circuit, the sensing circuit configured for receiving the compensated output signal.
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Abstract
A touch surface device having improved sensitivity and dynamic range is disclosed. In one embodiment, the touch surface device includes a touch-sensitive panel having at least one sense node for providing an output signal indicative of a touch or no-touch condition on the panel; a compensation circuit, coupled to the at least one sense node, for generating a compensation signal that when summed with the output signal removes an undesired portion of the output signal so as to generated a compensated output signal; and an amplifier having an inverting input coupled to the output of the compensation circuit and a non-inverting input coupled to a known reference voltage.
567 Citations
41 Claims
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1. A touch surface device, comprising:
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a touch-sensitive panel having a sense node configured for providing an output signal indicative of a touch or no-touch condition on the panel, the output signal including a static portion unaffected by a touch and a dynamic portion affected by the touch; a compensation circuit, coupled to the sense node, configured for generating a compensation signal that when summed with the output signal prior to demodulation of the output signal substantially removes the static portion of the output signal so as to generate a compensated output signal; and a sensing circuit coupled to the compensation circuit, the sensing circuit configured for receiving the compensated output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A computer system incorporating a touch surface device, comprising:
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a touch-sensitive panel comprising at least one sense node configured to generate an output signal indicative of touch or no-touch condition on the panel, the output signal including a static portion unaffected by a touch and a dynamic portion affected by the touch; a compensation circuit coupled to the at least one sense node and configured to generate a compensation signal for substantially offsetting the static portion of the output signal prior to demodulation of the output signal so as to generate a compensated output signal; and a processor coupled to compensation circuit and configured to receive and process the compensated output signal and perform one or more functions based on data provided by the compensated output signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A method of compensating an output signal generated by a touch surface device, the method comprising:
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generating the output signal at a sense node of the touch surface device, the output signal including a static portion unaffected by a touch and a dynamic portion affected by the touch; generating a compensation signal for substantially offsetting the static portion of the output signal; summing the output signal with the compensation signal prior to demodulation of the output signal to generate a compensated signal and amplifying the compensated signal with a desired gain. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method of compensating for an undesired portion of an output signal generated by an electronic device, the method comprising:
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receiving a periodic output signal from an output node of the electronic device, the output signal including a static portion unaffected by a touch and a dynamic portion affected by the touch; generating a periodic compensation signal having a substantially similar waveform as the periodic output signal but substantially 180 degrees out of phase with the periodic output signal; summing the periodic output signal and the periodic compensation signal prior to demodulation of the periodic output signal so as to generate a compensated signal, wherein the compensated signal substantially represents the periodic output signal with the static portion subtracted from the periodic output signal; providing the compensated signal to a first input of an amplifier; and providing a known reference voltage to a second input of the amplifier. - View Dependent Claims (32, 33, 34, 35, 36, 37)
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38. A computer system utilizing a touch surface device, comprising:
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means for generating the output signal at a sense node of the touch surface device, the output signal including a static portion unaffected by a touch and a dynamic portion affected by the touch; means for generating a compensation signal for substantially offsetting the static portion of the output signal; means for summing the output signal with the compensation signal prior to demodulation of the output signal to generate a compensated signal; and means for amplifying the compensated signal with a desired gain. - View Dependent Claims (39, 40)
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41. A circuit for compensating an output signal generated by an electronic device, comprising:
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means for receiving a periodic output signal from an output node of the electronic device, the output signal including a static portion unaffected by a touch and a dynamic portion affected by the touch; means for generating a periodic compensation signal having a substantially similar waveform as the periodic output signal but substantially 180 degrees out of phase with the periodic output signal; means for summing the periodic output signal and the periodic compensation signal prior to demodulation of the output signal so as to generate a compensated signal, wherein the compensated signal substantially represents the periodic output signal with the static portion subtracted from the periodic output signal; and means for amplifying the compensated signal with a desired gain.
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Specification