Background noise measurement and frequency selection in touch panel sensor systems
First Claim
1. A system comprising:
- a sensor configured to detect a change in capacitance associated with a touch upon a touch panel;
a measuring module coupled to the sensor;
an offset cancellation drive module coupled to the measuring module, the offset cancellation drive module configured to generate, during a sensor detection phase, a first drive signal having a first periodic waveform characteristic and the drive module configured to generate, during a noise measurement detection phase, a second drive signal having a second, constant voltage, waveform;
characteristic;
wherein the first drive signal and the second drive signal drive the sensor andthe measuring module is configured to measure, during the noise measurement phase, noise associated with the sensor having the first periodic waveform characteristic.
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Abstract
A touch panel sensor system that can dynamically measure noise and automatically switch to a frequency with minimal noise is described. The touch panel sensor system includes a sensor configured to detect a change in capacitance associated with a touch upon a touch panel. The system also includes a drive module configured to generate a drive signal having a first waveform characteristic (e.g., signal having a periodic waveform characteristic) during a first phase (e.g., sensor phase) and a second drive signal having a second waveform characteristic (e.g., constant voltage signal) during a second phase (e.g., noise detection phase). The first and second drive signals are configured to drive the sensor. The system also includes a measuring module coupled to the sensor that is configured to measure noise having the first waveform characteristic (e.g., periodic waveform characteristic) during the second phase.
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Citations
19 Claims
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1. A system comprising:
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a sensor configured to detect a change in capacitance associated with a touch upon a touch panel; a measuring module coupled to the sensor; an offset cancellation drive module coupled to the measuring module, the offset cancellation drive module configured to generate, during a sensor detection phase, a first drive signal having a first periodic waveform characteristic and the drive module configured to generate, during a noise measurement detection phase, a second drive signal having a second, constant voltage, waveform;
characteristic;
wherein the first drive signal and the second drive signal drive the sensor andthe measuring module is configured to measure, during the noise measurement phase, noise associated with the sensor having the first periodic waveform characteristic. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A system comprising:
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a sensor configured to detect a change in capacitance associated with a touch upon a touch panel; a measuring module coupled to the sensor; a drive module coupled to the sensor, the drive module configured to generate, during a sensor detection phase, a first drive signal having a first periodic waveform characteristic and, during a noise measurement detection phase, a second drive signal having a second, constant voltage, waveform characteristic different from the first waveform characteristic, the first drive signal and the second drive signal for driving the sensor; an offset cancellation module coupled to the measuring module, the offset cancellation module configured to furnish an adjustable capacitive value for the sensor; an offset cancellation drive module coupled to the offset cancellation module, the offset cancellation drive module configured to generate, during the sensor detection phase, a first offset cancellation drive signal having the first periodic waveform characteristic and a second offset cancellation drive signal having the second, constant voltage, waveform characteristic during the noise measurement detection phase, the first offset cancellation drive signal and the second offset cancellation drive signal for driving the offset cancellation module;
whereinthe measuring module is configured to detect noise having the first periodic waveform characteristic during the noise measurement detection phase, the noise associated with at least one of the sensor or the offset cancellation module. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. A method comprising:
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generating, during a sensor detection phase, a first drive signal having a first periodic waveform characteristic; generating, during a noise measurement detection phase, a second drive signal having a second, constant voltage, waveform characteristic;
wherein the first drive signal and the second drive signal drive the sensor;initiating, during the noise measurement detection phase, a first noise measurement comprising the first periodic waveform characteristic at a measuring module, the first noise measurement associated with a sensor configured to detect a change in capacitance associated with a touch upon a touch panel; determining whether the first noise measurement exceeds a predetermined threshold; and initiating a second noise measurement comprising the second, constant voltage, waveform characteristic when the first noise measurement exceeds the predetermined threshold. - View Dependent Claims (15, 16, 17, 18, 19)
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Specification