Method of compensating for retransmission effects in a touch sensor
In one embodiment, a method of compensating for retransmission effects in a touch sensor includes, in response to measuring a touch input on a display, generating a first matrix comprising a plurality of first measurements associated with a plurality of capacitive nodes of a touch sensor. The method also includes estimating an amount of retransmission associated with the touch input by generating a first vector comprising one or more second measurements associated with one or more first electrode lines of the touch sensor, generating a second vector comprising one or more third measurements associated with one or more second electrode lines of the touch sensor, and calculating an outer product of the first and second vectors. The method includes generating a revised indication of the touch input based on the first matrix and the estimated amount of retransmission.
1. A method for detecting a touch input comprising:
in response to measuring a touch input on a display, generating a first matrix comprising a plurality of first measurements associated with a plurality of capacitive nodes of a touch sensor, wherein each of the plurality of first measurements is indicative of a capacitance associated with a corresponding one of the plurality of capacitive nodes;
estimating an amount of retransmission associated with the touch input by performing operations comprising:
generating a first vector comprising one or more second measurements each indicative of a capacitance of a respective electrode line of a first plurality of electrode lines of the touch sensor in response to the touch input, wherein the first plurality of electrode lines are oriented along a first axis;
generating a second vector comprising one or more third measurements each indicative of a capacitance of a respective electrode line of a second plurality of electrode lines of the touch sensor in response to the touch input, wherein the second plurality of electrode lines are oriented along a second axis, the second axis being different than the first axis;
generating a second matrix by calculating an outer product of the first and second vectors; and
generating a revised indication of the touch input based on the first matrix and the second matrix.
2. The method of claim 1 , wherein generating the revised indication comprises adjusting the first matrix using the second matrix.
3. The method of claim 2 , wherein adjusting the first matrix using the second matrix comprises adding the second matrix to the first matrix.
4. The method of claim 1 , wherein estimating an amount of retransmission further comprises:
calculating a constant; and
multiplying the outer product by the constant.
5. The method of claim 4 , wherein the constant is calculated based on a total number of capacitive nodes of the touch sensor activated by the touch input.
6. The method of claim 1 , wherein the capacitance of one of the first plurality of electrode lines-comprises the capacitance between the touch input and one of the first plurality of electrode lines.
7. The method of claim 1 , wherein each of the capacitive nodes comprises an intersection point between one of the first plurality of electrode lines and one of the second plurality of electrode lines.
8. An apparatus comprising:
a display coupled to a touch sensor operable to receive a touch input;
a touch-sensor controller coupled to the touch sensor, the touch-sensor controller operable to:
in response to measuring the touch input, generate a first matrix comprising a plurality of first measurements associated with a plurality of capacitive nodes of the touch sensor, wherein each of the plurality of measurements is indicative of a capacitance associated with a corresponding one of the plurality of capacitive nodes;
estimate an amount of retransmission associated with the touch input by performing operations comprising:
generating a first vector comprising one or more second measurements each indicative of a capacitance of a respective electrode line of a first plurality of electrode lines of the touch sensor in response to the touch input, wherein the first plurality of electrode lines are oriented along a first axis;
generating a second vector comprising one or more third measurements each indicative of a capacitance of a respective electrode line of a second plurality of electrode lines of the touch sensor in response to the touch input, wherein the second plurality of electrode lines are oriented along a second axis, the second axis being different than the first axis;
generating a second matrix by calculating an outer product of the first and second vectors; and
generate a revised indication of the touch input based on the first matrix and the second matrix.
9. The apparatus of claim 8 , wherein the touch-sensor controller is further operable to generate the revised indication by adjusting the first matrix using the second matrix.
10. The apparatus of claim 9 , wherein adjusting the first matrix using the second matrix comprises adding the second matrix to the first matrix.
11. The apparatus of claim 8 , wherein the touch-sensor controller is further operable to estimate the amount of retransmission by:
calculating a constant; and
multiplying the outer product by the constant.
12. The apparatus of claim 11 , wherein the constant is calculated based on a total number of capacitive nodes of the touch sensor activated by the touch input.
13. The apparatus of claim 8 , wherein each of the capacitive nodes comprises an intersection point between one of the first plurality of electrode lines and one of the second plurality of electrode lines.
14. One or more computer-readable non-transitory storage media embodying logic that is operable when executed to:
in response to measuring a touch input on a display, generate a first matrix comprising a plurality of first measurements associated with a plurality of capacitive nodes of a touch sensor, wherein each of the plurality of first measurements is indicative of a capacitance associated with a corresponding one of the plurality of capacitive nodes;
estimate an amount of retransmission associated with the touch input by performing operations comprising:
generating a first vector comprising one or more second measurements each indicative of a capacitance of a respective electrode line of a first plurality of electrode lines of the touch sensor in response to the touch input, wherein the first plurality of electrode lines are oriented along a first axis;
generating a second vector comprising one or more third measurements each indicative of a capacitance of a respective electrode line of a second plurality of electrode lines of the touch sensor in response to the touch input, wherein the second plurality of electrode lines are oriented along a second axis, the second axis being different than the first axis;
generating a second matrix by calculating an outer product of the first and second vectors; and
generate a revised indication of the touch input based on the first matrix and the second matrix.
15. The media of claim 14 , wherein the logic is further operable when executed to generate the revised indication by adjusting the first matrix using the second matrix.
16. The media of claim 15 , wherein adjusting the first matrix using the second matrix comprises adding the second matrix to the first matrix.
17. The media of claim 14 , wherein the logic is further operable when executed to estimate the amount of retransmission by:
calculating a constant; and
multiplying the outer product by the constant.