Multi-scan touch sensing system and method
In some examples, a touch screen can perform a first touch scan to obtain first touch data and a second touch scan to obtain second touch data. The touch data resulting from the second touch scan may exclude respective noise (e.g., display-to-touch crosstalk (DTX) noise) or may include a reduced amount of the respective noise. In some examples, the electronic device can subtract the second touch data from the first touch data to obtain an estimate of the noise in the first touch data. In some examples, this noise estimate can be subtracted from the first touch data and an action can be performed based on the first touch data with the noise estimate removed.
1. An electronic device comprising:
a touch screen, wherein the touch screen includes a plurality of touch electrodes, and
one or more processors configured to perform a method comprising:
performing a first touch sensing operation for a first duration of time; and
performing a second touch sensing operation for a second duration of time different from the first duration of time;
generating a noise estimate at a subset of the plurality of touch electrodes based on the first touch sensing operation and the second touch sensing operation;
generating a noise estimate at the plurality of touch electrodes based on the noise estimate at the subset of the plurality of touch electrodes;
identifying a touch pattern based on the noise estimate at the subset of the plurality of touch electrodes and the first touch sensing operation; and
performing an action at the electronic device based on the identified touch pattern.
2. The electronic device of claim 1 , wherein the plurality of touch electrodes are disposed at unique x, y locations of the touch screen.
3. The electronic device of claim 1 , wherein generating the noise estimate at the plurality of touch electrodes based on the noise estimate at the subset of the plurality of touch electrodes includes up-sampling the noise estimate at the subset of the plurality of the touch electrodes.
4. The electronic device of claim 3 , wherein the method further includes:
prior to performing the first touch sensing operation and second touch sensing operation:
calibrating a spatial correlation of noise, wherein the up-sampling of the noise estimate at the subset of the plurality of the touch electrodes is based on the spatial correlation.
5. The electronic device of claim 4 , wherein the method further includes:
prior to performing the first touch sensing operation and second touch sensing operation:
selecting the subset of the plurality of the touch electrodes based on the spatial correlation of the noise.
6. The electronic device of claim 1 , wherein the second duration of time is longer than the first duration of time.
7. The electronic device of claim 1 , wherein:
the first touch sensing operation is performed at the plurality of touch electrodes, and
the second touch sensing operation is performed at the subset of the plurality of touch electrodes.
8. The electronic device of claim 1 , wherein:
performing the first touch sensing operation includes:
applying first touch voltages to the plurality of touch electrodes for a first period of time; and
integrating first charges of the plurality of touch electrodes for a second period of time, the first charges corresponding to first touch signals; and
performing the second touch sensing operation includes:
applying second touch voltages to the subset of touch electrodes for a third period of time different from the first period of time; and
integrating second charges of the plurality of the subset of touch electrodes for a fourth period of time different from the second period of time, the second charges corresponding to second touch signals.
9. The electronic device of claim 1 , wherein generating the noise estimate at the subset of the plurality of touch electrodes includes subtracting second touch signals obtained via the second touch sensing operation from first touch signals obtained via the first touch sensing operation.
10. The electronic device of claim 1 , wherein identifying the touch pattern based on the noise estimate at the subset of the plurality of touch electrodes and the first touch sensing operation includes subtracting the noise estimate at the plurality of touch electrodes from first touch signals obtained via the first touch sensing operation.
11. A method performed at an electronic device including a touch screen, wherein the touch screen includes a plurality of touch electrodes, the method comprising:
performing a first touch sensing operation for a first duration of time; and
performing a second touch sensing operation for a second duration of time different from the first duration of time;
generating a noise estimate at a subset of the plurality of touch electrodes based on the first touch sensing operation and the second touch sensing operation;
generating a noise estimate at the plurality of touch electrodes based on the noise estimate at the subset of the plurality of touch electrodes;
identifying a touch pattern based on the noise estimate at the subset of the plurality of touch electrodes and the first touch sensing operation; and
performing an action at the electronic device based on the identified touch pattern.
12. The method of claim 11 , wherein:
performing the first touch sensing operation includes:
applying first touch voltages to the plurality of touch electrodes for a first period of time; and
integrating first charges of the plurality of touch electrodes for a second period of time, the first charges corresponding to first touch signals; and
performing the second touch sensing operation includes:
applying second touch voltages to the subset of touch electrodes for a third period of time different from the first period of time; and
integrating second charges of the plurality of the subset of touch electrodes for a fourth period of time different from the second period of time, the second charges corresponding to second touch signals.
13. A non-transitory computer readable storage medium storing instructions that, when executed at an electronic device including a touch screen, wherein the touch screen includes a plurality of touch electrodes, causes the electronic device to perform a method comprising:
performing a first touch sensing operation for a first duration of time; and
performing a second touch sensing operation for a second duration of time different from the first duration of time;
generating a noise estimate at a subset of the plurality of touch electrodes based on the first touch sensing operation and the second touch sensing operation;
generating a noise estimate at the plurality of touch electrodes based on the noise estimate at the subset of the plurality of touch electrodes;
identifying a touch pattern based on the noise estimate at the subset of the plurality of touch electrodes and the first touch sensing operation; and
performing an action at the electronic device based on the identified touch pattern.
14. The non-transitory computer readable storage medium of claim 13 , wherein the plurality of touch electrodes are disposed at unique x, y locations of the touch screen.
15. The non-transitory computer readable storage medium of claim 13 , wherein generating the noise estimate at the plurality of touch electrodes based on the noise estimate at the subset of the plurality of touch electrodes includes up-sampling the noise estimate at the subset of the plurality of the touch electrodes.
16. The non-transitory computer readable storage medium of claim 13 , wherein the second duration of time is longer than the first duration of time.
17. The non-transitory computer readable storage medium of claim 13 , wherein:
the first touch sensing operation is performed at the plurality of touch electrodes, and
the second touch sensing operation is performed at the subset of the plurality of touch electrodes.
18. The non-transitory computer readable storage medium of claim 13 , wherein:
performing the first touch sensing operation includes:
applying first touch voltages to the plurality of touch electrodes for a first period of time; and
integrating first charges of the plurality of touch electrodes for a second period of time, the first charges corresponding to first touch signals; and
performing the second touch sensing operation includes:
applying second touch voltages to the subset of touch electrodes for a third period of time different from the first period of time; and
integrating second charges of the plurality of the subset of touch electrodes for a fourth period of time different from the second period of time, the second charges corresponding to second touch signals.
19. The non-transitory computer readable storage medium of claim 13 , wherein generating the noise estimate at the subset of the plurality of touch electrodes includes subtracting second touch signals obtained via the second touch sensing operation from first touch signals obtained via the first touch sensing operation.
20. The non-transitory computer readable storage medium of claim 13 , wherein identifying the touch pattern based on the noise estimate at the subset of the plurality of touch electrodes and the first touch sensing operation includes subtracting the noise estimate at the plurality of touch electrodes from first touch signals obtained via the first touch sensing operation.