Front-end signal compensation
AssigneeApple Inc.
InventorsSteve Porter Hotelling, Brian Richards Land
Life of this patent
Estimating the term…
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.
Claims41
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.
A computer system incorporating a touch surface device, comprising:
- 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.
A method of compensating an output signal generated by a touch surface device, the method comprising:
- 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.
A method of compensating for an undesired portion of an output signal generated by an electronic device, the method comprising:
- 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.
A computer system utilizing a touch surface device, comprising:
- 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.
A circuit for compensating an output signal generated by an electronic device, comprising:
- 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.
Dependencies are inferred from the claim text.