Orthogonal frequency scan scheme in touch system
First Claim
1. A system comprising:
- signal generator operable to generate a plurality of signals having a plurality of orthogonal frequencies, each orthogonal frequency of the plurality of orthogonal frequencies being a different frequency, the plurality of signals simultaneously driving a plurality of rows of a touch sensor, wherein frequencies of the plurality of orthogonal frequencies are spaced by a frequency that is at least a reciprocal of a predetermined measurement period of the touch sensor, and a highest orthogonal frequency of the plurality of orthogonal frequencies is less than twice a lowest orthogonal frequency of the plurality of frequencies.
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Accused Products
Abstract
System and processes for transmitting orthogonal frequencies on a touch sensor are provided. In one example process, the rows of the sensor panel can have signals transmitted thereon having orthogonal frequencies. The orthogonal frequencies can be separated by a frequency spacing (Δf) that is at least the reciprocal of a measurement period τ (e.g., an integration time) of the touch sensor. Touch events cause and correspond to signals on the columns, which can be received by a receive system including appropriate amplifiers. The orthogonal frequencies can be detected by the receiver with a Fourier Transform or filter bank. Separate digitization and signal processing can be implemented for every column. The receiver can measure the quantity of each of the orthogonal transmitted signals present on each column, identifying the rows in touch with each column and may also provide additional (e.g., qualitative) information concerning the touch.
11 Citations
14 Claims
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1. A system comprising:
signal generator operable to generate a plurality of signals having a plurality of orthogonal frequencies, each orthogonal frequency of the plurality of orthogonal frequencies being a different frequency, the plurality of signals simultaneously driving a plurality of rows of a touch sensor, wherein frequencies of the plurality of orthogonal frequencies are spaced by a frequency that is at least a reciprocal of a predetermined measurement period of the touch sensor, and a highest orthogonal frequency of the plurality of orthogonal frequencies is less than twice a lowest orthogonal frequency of the plurality of frequencies. - View Dependent Claims (2, 3, 4)
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5. A system comprising:
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a touch sensor comprising; a first row; and a second row; and signal generator coupled to the first and second rows and operable to; generate on the first row a first signal having a first frequency; and generate on the second row a second 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 at least a reciprocal of a predetermined measurement period of the touch sensor, and either the first frequency is less than twice the second frequency or the second frequency is less than twice the first frequency, and the signal generator simultaneously generating signals on the first row with the first signal and the second row with the second signal. - View Dependent Claims (6, 7)
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8. A system comprising:
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a touch sensor comprising; a plurality of rows; and a column capacitively coupled to the plurality of rows; and signal generator coupled to the plurality of rows and operable to simultaneously generate on the plurality of rows a plurality of row signals, each row signal of the plurality of row signals having a different frequency, wherein; the plurality of row signals are spaced by a frequency that is a reciprocal of a predetermined measurement period of the touch sensor, and a highest row signal frequency of the plurality of row signals is set to be less than twice a lowest row signal frequency of the plurality of row signals, the column is operable to generate a column signal in response to the plurality of rows being driven by the row signals, and the column signal comprises an interference component having a frequency corresponding to a difference in frequency between the frequencies of the row signals. - View Dependent Claims (9, 10)
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11. A system comprising:
signal generator operable to generate a plurality of signals having a plurality of orthogonal frequencies, each orthogonal frequency of the plurality of orthogonal frequencies being a different frequency, the plurality of signals simultaneously driving a plurality of rows of a touch sensor, wherein frequencies of the plurality of orthogonal frequencies are spaced by a frequency that is a reciprocal of a predetermined measurement period of the touch sensor, and a highest orthogonal frequency of the plurality of orthogonal frequencies is less than twice a lowest orthogonal frequency of the plurality of frequencies. - View Dependent Claims (12, 13, 14)
Specification