PCAP with enhanced immunity to water contaminants
System, method, and computer program product embodiments are provided that can support touch interaction on a projective capacitive (PCAP) display system in the presence of water contamination. According to an embodiment, a system includes a touchscreen coupled to a controller. The controller determines the presence of water contamination on the touchscreen, and obtains measurements during a mixed-mode measurement frame that includes a self-mode measurement and a mutual-mode measurement. Based on the measurements obtained, the controller determines a touch on the touchscreen in the presence of the water contamination on the touchscreen. In some embodiments, the self-mode measurement includes measurements collected at a both lower and a higher drive frequency, the higher drive frequency may be in the frequency range of 100 kHz to 500 kHz. In another embodiment, the self-mode measurement includes simultaneously measuring both horizontal-electrodes and vertical-electrodes.
1. A projected capacitive (PCAP) touch system comprising:
a touchscreen; and
a controller coupled to the touchscreen, the controller configured to:
obtain measurements during a mixed-mode measurement frame comprising two self-mode measurements followed by a mutual-mode measurement, wherein the two self-mode measurements comprise a lower drive frequency measurement followed by and a higher drive frequency measurement,
wherein the two self-mode measurements determine areas on the touchscreen where the mutual-mode measurement is collected; and
based on the measurements, determine a touch on the touchscreen in a presence of water contamination on the touchscreen.
2. The PCAP touch system of claim 1 , wherein a lower drive frequency of the lower drive frequency measurement is in a range from 10 kHz to 100 kHz.
3. The PCAP touch system of claim 1 , wherein a higher drive frequency of the higher drive frequency measurement is in a range from 100 kHz to 500 kHz.
4. The PCAP touch system of claim 1 , wherein a higher drive frequency of the higher drive frequency measurement is at least five to ten times that of a lower drive frequency of the lower drive frequency measurement.
5. The PCAP touch system of claim 1 , wherein the controller is further configured to:
measure the water contamination, based on the lower drive frequency measurement and the higher drive frequency measurement.
6. The PCAP touch system of claim 5 , wherein to measure the water contamination, the controller is configured to:
determine a quantity of the water contamination; and
determine a location of the water contamination.
7. The PCAP touch system of claim 1 , wherein the self-mode measurement comprises a third drive frequency measurement, wherein a corresponding third drive frequency of the third drive frequency measurement is between a lower drive frequency of the lower drive frequency measurement and a higher drive frequency of the higher drive frequency measurement.
8. The PCAP touch system of claim 1 , wherein the controller is further configured to:
based on the measurements obtained, transition to obtain measurements in: a mutual-mode only measurement frame or a self-mode only measurement frame.
9. The PCAP touch system of 1 , wherein the controller is further configured to:
create a mask comprising a range of vertical electrodes and a range of horizontal electrodes;
determine a set of electrode intersections corresponding to non-zero values of a self-mode measurement obtained within the two self-mode measurements; and
apply the mask to electrode intersections of the set of electrode intersections.
10. The PCAP touch system of claim 9 , wherein the controller is further configured to:
identify sub-masked areas of the touchscreen where the mask is applied; and
collect mutual-mode measurements from the sub-masked areas of the touchscreen.
11. The PCAP touch system of claim 9 , wherein for an electrode intersection (r, s) of the set of electrode intersections, the range of vertical electrodes r comprises 20<=r<=40 or the range of horizontal electrodes comprises 0<=s<=20.
12. A method comprising:
obtaining measurements from a touchscreen during a mixed-mode measurement frame comprising two self-mode measurements followed by a mutual-mode measurement, wherein the two self-mode measurements comprise a lower drive frequency measurement followed by a higher drive frequency measurement,
wherein the two self-mode measurements determine areas on the touchscreen where the mutual-mode measurement is collected; and
based on the measurements, determining a touch on the touchscreen in a presence of water contamination on the touchscreen.
13. The method of claim 12 , wherein a lower drive frequency of the lower drive frequency measurement is in a range from 10 kHz to 100 kHz.
14. The method of claim 12 , wherein a higher drive frequency of the higher drive frequency measurement is in a range from 100 kHz to 500 kHz.
15. The method of claim 12 , wherein a higher drive frequency of the higher drive frequency measurement is at least five to ten times that of a lower drive frequency of the lower drive frequency measurement.
16. The method of claim 12 , further comprising measuring the water contamination, based on the lower drive frequency measurement and the higher drive frequency measurement.
17. The method of claim 16 , wherein the measuring the water contamination comprises:
determining a quantity of the water contamination; and
determining a location of the water contamination.
18. The method of claim 12 , wherein the self-mode measurement comprises a third drive frequency measurement, wherein a corresponding third drive frequency of the third drive frequency measurement is between a lower drive frequency of the lower drive frequency measurement and a higher drive frequency of the higher drive frequency measurement.
19. The method of claim 11 , further comprising:
creating a mask comprising a range of vertical electrodes and a range of horizontal electrodes;
determining a set of electrode intersections corresponding to non-zero values of a self-mode measurement obtained within the two self-mode measurements; and
applying the mask to electrode intersections of the set of electrode intersections.
20. A non-transitory computer-readable medium storing instructions that, when executed by a processor of a first electronic device, cause the processor to perform operations, the operations comprising:
obtaining measurements from a touchscreen during a mixed-mode measurement frame comprising: two self-mode measurements followed by a mutual-mode measurement, wherein the two self-mode measurements comprise a lower drive frequency measurement followed by a higher drive frequency measurement,
wherein the two self-mode measurements determine areas on the touchscreen where the mutual-mode measurement is collected; and
based on the measurements, determining a touch on the touchscreen in a presence of water contamination on the touchscreen.