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.
Claims25
A front-end signal compensation apparatus, comprising:
- a compensation circuit coupled to a sense node, the compensation circuit configured for
- receiving a sense signal indicative of a detected touch and including a static portion unaffected by the touch and a dynamic portion affected by the touch, and
- generating a compensation signal that, when combined with the sense signal prior to further processing of the sense signal, substantially removes the static portion of the sense signal so as to generate a compensated sense signal;
- and
- a sensing circuit coupled to the compensation circuit, the sensing circuit configured for receiving the compensated sense signal.
A computer system incorporating a front-end signal compensation apparatus, comprising:
- a touch-sensitive device having a sense node configured for providing a sense signal indicative of a detected touch at the device, the sense signal including a static portion unaffected by the touch and a dynamic portion affected by the touch;
- a compensation circuit coupled to the sense node and configured for generating a compensation signal for substantially offsetting the static portion of the sense signal prior to further processing of the sense signal so as to generate a compensated sense signal;
- and
- a processor coupled to the compensation circuit and configured to perform one or more functions based on data within the compensated sense signal.
A method of compensating a sense signal generated by a touch-sensitive device, the method comprising:
- generating the sense signal at a sense node of the touch-sensitive device, the sense signal including a static portion unaffected by a touch and a dynamic portion affected by the touch;
- generating a compensation signal for offsetting the static portion of the sense signal;
- combining the sense signal with the compensation signal prior to further processing of the sense signal to generate a compensated sense signal and
- amplifying the compensated sense signal with a desired gain.
A method of compensating for an undesired portion of an output signal generated by a touch-sensitive device, the method comprising:
- receiving a periodic sense signal from a sense node of the touch-sensitive device, the periodic sense 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 sense signal but substantially 180 degrees out of phase with the periodic sense signal;
- combining the periodic sense signal and the periodic compensation signal prior to further processing of the periodic sense signal so as to generate a compensated sense signal, wherein the compensated sense signal represents the periodic sense signal with the static portion subtracted;
- and
- providing the compensated sense signal to a charge amplifier.
A computer system utilizing a touch-sensitive device, comprising:
- means for generating a sense signal at a sense node of the touch-sensitive device, the sense signal including a static portion unaffected by a touch and a dynamic portion affected by the touch;
- means for generating a compensation signal for offsetting the static portion of the sense signal;
- means for combining the sense signal with the compensation signal prior to further processing of the sense signal to generate a compensated sense signal;
- and
- means for amplifying the compensated sense signal with a desired gain.
A circuit for compensating a sense signal generated by a touch-sensitive device, comprising:
- means for receiving a periodic sense signal from a sense node of the touch-sensitive device, the sense 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 sense signal but substantially 180 degrees out of phase with the periodic sense signal;
- means for combining the periodic sense signal and the periodic compensation signal prior to further processing of the sense signal so as to generate a compensated sense signal, wherein the compensated sense signal represents the periodic sense signal with the static portion subtracted;
- and
- means for amplifying the compensated sense signal with a desired gain.
Dependencies are inferred from the claim text.