Orthogonal frequency scan scheme in touch system
First Claim
1. A system comprising:
- drive circuitry operable to generate a plurality of stimulation signals having a plurality of orthogonal frequencies, each orthogonal frequency of the plurality of orthogonal frequencies being a different frequency, the plurality of stimulation signals for simultaneously driving a plurality of drive electrodes of a touch sensor, wherein frequencies of the plurality of orthogonal frequencies are separated by a frequency that is inversely proportional to an integration time of the touch sensor.
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Abstract
Systems and processes for stimulating a touch sensor panel using orthogonal frequencies are provided. In one example process, the drive lines of the touch sensor panel can be stimulated with stimulation signals having orthogonal frequencies. The orthogonal frequencies can be separated by a frequency that is inversely proportional to an integration time of the touch sensor panel. The touch signals generated in response to the stimulation signals can be amplified, converted into digital form, demodulated using the orthogonal frequencies, and integrated over the integration time. Integrating the demodulated signals over a length of time that is inversely proportional to the frequency spacing between the orthogonal frequencies reduces or eliminates interference in the touch signals caused by the stimulation signals having different frequencies.
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Citations
22 Claims
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1. A system comprising:
drive circuitry operable to generate a plurality of stimulation signals having a plurality of orthogonal frequencies, each orthogonal frequency of the plurality of orthogonal frequencies being a different frequency, the plurality of stimulation signals for simultaneously driving a plurality of drive electrodes of a touch sensor, wherein frequencies of the plurality of orthogonal frequencies are separated by a frequency that is inversely proportional to an integration time of the touch sensor. - View Dependent Claims (2, 3, 4)
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5. A system comprising:
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a touch sensor comprising; a first drive electrode; and a second drive electrode; and drive circuitry coupled to the first and second drive electrodes and operable to; drive the first drive electrode with a first stimulation signal having a first frequency; and drive the second drive electrode with a second stimulation signal having a second frequency, the second frequency different from the first frequency, wherein; a difference between the first frequency and the second frequency is inversely proportional to an integration time of the touch sensor, and the drive circuitry simultaneously drives the first electrode with the first stimulation signal and the second electrode with the second stimulation signal. - View Dependent Claims (6, 7, 8, 9)
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10. A system comprising:
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a touch sensor comprising; a plurality of drive electrodes; and a sense electrode capacitively coupled to the plurality of drive electrodes; and drive circuitry coupled to the plurality of drive electrodes and operable to simultaneously drive the plurality of drive electrodes with a plurality of stimulation signals, each stimulation signal of the plurality of stimulation signals having a different frequency, wherein; the plurality of stimulation signals are spaced by a frequency that is inversely proportional to an integration time of the touch sensor, the sense electrode is operable to generate a touch signal in response to the plurality of drive electrodes being driven by the stimulation signals, and the touch signal comprises an interference component having a frequency corresponding to a difference in frequency between the frequencies of the stimulation signals. - View Dependent Claims (11, 12, 13, 14)
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15. A system comprising:
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a touch sensor comprising a plurality of drive electrodes; and drive circuitry coupled to the plurality of drive electrodes and operable to; drive a first set of the plurality of drive electrodes with a first plurality of stimulation signals, wherein each of the first plurality of stimulation signals has a first frequency, and wherein each of the first plurality of stimulation signals has a different phase offset; and drive a second set of the plurality of drive electrodes with a second plurality of stimulation signals, wherein each of the second plurality of stimulation signals has a second frequency different from the first frequency, wherein each of the second plurality of stimulation signals has a different phase offset, wherein; the first frequency is orthogonal to the second frequency and a difference between the first frequency and the second frequency is inversely proportional to an integration time of the touch sensor, and at least one drive electrode of the first set of drive electrodes and at least one drive electrode of the second set of drive electrodes are driven simultaneously. - View Dependent Claims (16, 17, 18)
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19. A method for stimulating a touch sensor, the method comprising:
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simultaneously stimulating a plurality of sets of drive electrodes with a plurality of stimulation signals having orthogonal frequencies, the plurality of stimulation signals comprising a first signal having a first frequency and a second signal having a second frequency different from the first frequency; receiving a plurality of touch signals generated in response to the plurality of stimulation signals; demodulating the plurality of touch signals using the orthogonal frequencies of the plurality of stimulation signals; and integrating the demodulated plurality of touch signals over an integration time of the touch sensor, the integration time being inversely proportional to a difference between the first frequency and the second frequency by a positive integer multiple. - View Dependent Claims (20, 21, 22)
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Specification