Touch detection using multiple simultaneous frequencies
First Claim
1. A method for obtaining a plurality of values used to generate an image of touch from touch sensor circuitry, comprising:
- simultaneously applying a plurality of stimulation signals including positive and negative phases of a plurality of different stimulation frequencies to a plurality of drive lines of the touch sensor circuitry in a particular distribution, wherein one stimulation signal is applied to each of the drive lines;
receiving a sense signal from each of a plurality of sense lines of the touch sensor circuitry into a different sense channel;
demodulating the sense signal received into each sense channel with demodulation signals at a plurality of different demodulation frequencies, each demodulation frequency being the same frequency as one of the stimulation frequencies, the demodulation signals at each demodulation frequency being in-phase with either the positive or negative phase of the corresponding stimulation signal;
accumulating the sense signals demodulated with the plurality of demodulation frequencies in each sense channel to generate a plurality of values representing the accumulated demodulated sense signals for each sense channel; and
storing the plurality of values for all sense channels.
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Abstract
The use of multiple stimulation frequencies and phases to generate an image of touch on a touch sensor panel is disclosed. Each of a plurality of sense channels can be coupled to a column in a touch sensor panel and can have multiple mixers. Each mixer in the sense channel can utilize a circuit capable generating a demodulation frequency of a particular frequency. At each of multiple steps, various phases of selected frequencies can be used to simultaneously stimulate the rows of the touch sensor panel, and the multiple mixers in each sense channel can be configured to demodulate the signal received from the column connected to each sense channel using the selected frequencies. After all steps have been completed, the demodulated signals from the multiple mixers can be used in calculations to determine an image of touch for the touch sensor panel at each frequency.
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Citations
22 Claims
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1. A method for obtaining a plurality of values used to generate an image of touch from touch sensor circuitry, comprising:
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simultaneously applying a plurality of stimulation signals including positive and negative phases of a plurality of different stimulation frequencies to a plurality of drive lines of the touch sensor circuitry in a particular distribution, wherein one stimulation signal is applied to each of the drive lines; receiving a sense signal from each of a plurality of sense lines of the touch sensor circuitry into a different sense channel; demodulating the sense signal received into each sense channel with demodulation signals at a plurality of different demodulation frequencies, each demodulation frequency being the same frequency as one of the stimulation frequencies, the demodulation signals at each demodulation frequency being in-phase with either the positive or negative phase of the corresponding stimulation signal; accumulating the sense signals demodulated with the plurality of demodulation frequencies in each sense channel to generate a plurality of values representing the accumulated demodulated sense signals for each sense channel; and storing the plurality of values for all sense channels. - View Dependent Claims (2, 3, 4, 5)
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6. In a system including sensor circuitry having a plurality of drive lines being simultaneously driven with a plurality of stimulation signals including positive and negative phases of a plurality of different stimulation frequencies in a particular distribution, wherein one stimulation signal is applied to each of the drive lines, a method for obtaining a plurality of values used to generate an image of touch, the method comprising:
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demodulating a sense signal received on each sense line of the sensor circuitry with demodulation signals at a plurality of different demodulation frequencies, each demodulation frequency being the same frequency as one of the stimulation frequencies, the demodulation signals at each demodulation frequency being in-phase with either the positive or negative phase of the corresponding stimulation signal; and accumulating each of the plurality of demodulated sense signals for each sense line to generate the plurality of values representing the accumulated demodulated sense signals. - View Dependent Claims (7, 8, 9, 10)
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11. An apparatus for obtaining a plurality of values used to generate an image of touch from touch sensor circuitry, comprising:
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a plurality of sense channels, each sense channel including a charge amplifier configured for receiving a signal from a different sense line of the touch sensor circuitry, an output of the charge amplifier coupled to an input of a multiplexer, a plurality of mixers coupled to an output of the multiplexer, one frequency generator circuit coupled to each of the plurality of mixers for generating a demodulation frequency, and one accumulator coupled to each of the plurality of mixers for generating a value representing an accumulated mixer output; wherein each frequency generator circuit in each sense channel generates a demodulation signal at one of a plurality of different demodulation frequencies, the different demodulation frequencies corresponding to different stimulation frequencies of a plurality of stimulation signals simultaneously applied with different phases to drive lines of the touch sensor circuitry, wherein one stimulation signal is applied to each of the drive lines. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A non-transitory computer readable storage medium storing program code for obtaining a plurality of values used to generate an image of touch from touch sensor circuitry, the program code for performing a method comprising:
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simultaneously applying a plurality of stimulation signals including positive and negative phases of a plurality of different stimulation frequencies to a plurality of drive lines of the touch sensor circuitry in a particular distribution, wherein one stimulation signal is applied to each of the drive lines; receiving a sense signal from each of a plurality of sense lines of the touch sensor circuitry into a different sense channel; demodulating the sense signal received into each sense channel with demodulation signals at a plurality of different demodulation frequencies, each demodulation frequency being the same frequency as one of the stimulation frequencies, the demodulation signals at each demodulation frequency being in-phase with either the positive or negative phase of the corresponding stimulation signal; accumulating the sense signals demodulated with the plurality of demodulation frequencies in each sense channel to generate a plurality of values representing the accumulated demodulated sense signals for each sense channel; and storing the plurality of values for all sense channels. - View Dependent Claims (19, 20, 21, 22)
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Specification