Touchscreen data processing
First Claim
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1. A method comprising:
- sequentially integrating and converting charge from each of a plurality of sensing capacitors in an array to generate digital data, the digital data including sample values corresponding to a respective measured capacitance for each of the plurality of sensing capacitors;
forming a sliding window of the digital sample values using a sample aperture of size W, wherein W is an integer greater than 2, wherein a position of each sample value within the sliding window is based on a sequence in which it was generated, and wherein border values are mirrored to enable the sliding window to include W samples for each position of the sliding window;
for each respective position of the sliding window;
sorting the respective sample values in the sliding window;
multiplying each sorted sample value in the sliding window by a respective predetermined weight value based on a respective sort position of the sample valued within the sliding window, wherein the weights include a plurality of non-zero values; and
summing products of the multiplied sample values, and outputting the sum as a filtered sample value for the respective position of the sliding window;
summing a plurality of the filtered sample values to form an accumulated sample value; and
using the accumulated sample value to determined a position of at least one contact on the touch sensor array.
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Abstract
Capacitive touch sensors and touchscreen data processing methods are provided. In one embodiment, the method includes sequentially integrating and converting charge from each of a plurality of sensing capacitors in an array to digital data, the digital data including sample values corresponding to a measured capacitance for each of the plurality of sensing capacitors. Noise is then separated from useful information by filtering the sample values on a sample-by-sample basis. Finally, the filtered sample values are summed and a position of at least one contact on the array determined using the filtered capacitance values. Other embodiments are also provided.
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Citations
15 Claims
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1. A method comprising:
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sequentially integrating and converting charge from each of a plurality of sensing capacitors in an array to generate digital data, the digital data including sample values corresponding to a respective measured capacitance for each of the plurality of sensing capacitors; forming a sliding window of the digital sample values using a sample aperture of size W, wherein W is an integer greater than 2, wherein a position of each sample value within the sliding window is based on a sequence in which it was generated, and wherein border values are mirrored to enable the sliding window to include W samples for each position of the sliding window; for each respective position of the sliding window; sorting the respective sample values in the sliding window; multiplying each sorted sample value in the sliding window by a respective predetermined weight value based on a respective sort position of the sample valued within the sliding window, wherein the weights include a plurality of non-zero values; and summing products of the multiplied sample values, and outputting the sum as a filtered sample value for the respective position of the sliding window; summing a plurality of the filtered sample values to form an accumulated sample value; and using the accumulated sample value to determined a position of at least one contact on the touch sensor array. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system comprising:
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an analog front end configured to sequentially integrate and convert charge from each of a plurality of sensing capacitors of a touch sensor array to digital data; and a channel engine to receive digital data from the analog front end and generate of sample values corresponding to a measured capacitance for the plurality of sensing capacitors, the channel engine including; a sorting filter with weights (SFW) including a sliding window having a sample aperture of size (W), wherein W is an integer greater than 2, wherein a position of each sample value within the sliding window is based on a sequence in which it was generated, and wherein border values are mirrored to enable the sliding window to include W samples for each position of the sliding window, the SFW configured to; for each respective position of the sliding window; sorting the respective sample values in the sliding window; multiply each sorted sample value in the sliding window by a respective predetermined weight value based on a respective sort position of the sample value within the sliding window, wherein the weights include a plurality a non-zero values; and sum products of the multiplied sample values, and output the sum as a filtered sample value for the respective position of the sliding window; and a digital section configured to; sum a plurality of the filtered sample values to form an accumulated sample value; and use the accumulated sample value to determined a position of at least one contact on the touch sensor array. - View Dependent Claims (10)
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- 9. The system of 8, further comprising an amplitude filter configured to limit amplitude of each of the digital sample values.
Specification