CAPACITIVE TOUCH SCREEN INTERFERENCE DETECTION AND OPERATION

• US 20120249476A1
• Filed: 03/29/2012
• Published: 10/04/2012
• Est. Priority Date: 03/29/2011
• Status: Active Grant

• Current Assignee: Omnivision TDDI Ontario Limited Partnership
• Original Assignee: Synaptics Incorporated
• Inventors: Dattalo, Tracy Scott, Reynolds, Joseph Kurth, Schwartz, Adam, Hodgson, Robin
• Granted Patent: US 9,952,720 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A processing system for a capacitive touch screen comprises sensor circuitry and control logic. The sensor circuitry is configured to communicatively couple with sensor electrodes of the capacitive touch screen. The control logic is configured to operate the capacitive touch screen in a first mode comprising interference sensing at a first level and input object sensing. The control logic is also configured to operate the capacitive touch screen in a second mode instead of the first mode in response to: interference measured in the first mode meeting an interference condition; and a determination that input is in a sensing region of the capacitive touch screen. Operating in the first mode, interference sensing is performed during a non-display update time. Operating in the second mode, interference sensing with the capacitive touch screen is either not performed or is performed at a second level, lower in fidelity than the first level.

Claims

1. A processing system for a capacitive touch screen, said processing system comprising:

sensor circuitry configured to be communicatively coupled with sensor electrodes of said capacitive touch screen; and

control logic configured to;

operate said capacitive touch screen in a first mode comprising interference sensing at a first level and input object sensing; and

operate said capacitive touch screen in a second mode instead of in said first mode in response to;

interference measured in said first mode meeting an interference condition; and

a determination that input is in a sensing region of said capacitive touch screen,

wherein, interference sensing while in said first mode is performed during a non-display update time, and while in said second mode, interference sensing is either not performed or else performed at a second level that is lower in fidelity than said first level.

2. The processing system of claim 1, wherein said processing system further comprises display circuitry configured to update a display of said capacitive touch screen and wherein the sensor electrodes of the capacitive touch screen comprise common electrodes used for updating the display and capacitive sensing.

3. The processing system of claim 2, wherein said common electrodes are maintained in a non-transmitting state during interference sensing in said first mode.

4. The processing system of claim 1, wherein said control logic is further configured to:

exit said second mode in response to a second determination while in said second mode that no input is in said sensing region.

5. The processing system of claim 1, wherein said control logic is further configured to:

enter said first mode in response to a second determination that no input has been sensed in said sensing region for a predetermined period.

6. The processing system of claim 1, wherein said control logic is further configured to:

enter said first mode in response to experiencing signal corruption while in said second mode.

7. The processing system of claim 1, wherein said control logic is further configured to:

operate said capacitive touch screen in a third mode in response to a second determination, said second determination comprising that no input has been sensed in said sensing region for a predetermined period, wherein input sensing is performed at a lower fidelity in said third mode than in said first mode.

8. The processing system of claim 7, wherein said control logic is further configured to:

operate said capacitive touch screen in said first mode in response to a third determination, said third determination comprising input being sensed in said sensing region while in said third mode.

9. The processing system of claim 1, wherein said control logic is further configured to:

implement an interference avoidance action while in said first mode in response to said interference condition not being met.

10. The processing system of claim 9, wherein said interference avoidance action is selected from the group of interference avoidance actions consisting of:

modifying a sensing frequency, modifying a filtering operation, increasing a code length utilized in a code division multiplexing sensing scheme, and implementing a non-linear filtering technique.

11. A capacitive touch screen comprising:

a plurality of sensor electrodes; and

a processing system coupled with said plurality of plurality of sensor electrodes, said processing system configured to;

operate said capacitive touch screen in a first mode comprising interference sensing at a first level and input object sensing; and

operate said capacitive touch screen in a second mode instead of in said first mode in response to;

interference measured in said first mode meeting an interference condition; and

a determination that input is in a sensing region of said capacitive touch screen,

wherein, interference sensing while in said first mode is performed during a non-display update time, and while in said second mode, interference sensing is either not performed or else performed at a second level that is lower in fidelity than said first level.

12. The capacitive touch screen of claim 11, wherein the processing system comprises display circuitry configured to update a display of said capacitive touch screen and wherein the sensor electrodes of the capacitive touch screen comprise common electrodes used for updating the display and capacitive sensing.

13. The capacitive touch screen of claim 12 wherein said common electrodes are maintained in a non-transmitting state during interference sensing in said first mode.

14. The capacitive touch screen of claim 11, wherein said processing system is further configured to:

exit said second mode in response to a second determination while in said second mode that no input is in said sensing region.

15. The capacitive touch screen of claim 11, wherein said processing system is further configured to:

enter said first mode in response to a second determination that no input has been sensed in said sensing region for a predetermined period.

16. The capacitive touch screen of claim 11, wherein said processing system is further configured to:

enter said first mode in response to experiencing signal corruption while in said second mode.

17. The capacitive touch screen of claim 11, wherein said processing system is further configured to:

operate said capacitive touch screen in a third mode in response to a second determination, said second determination comprising that no input has been sensed in said sensing region for a predetermined period, wherein input sensing is performed at a lower fidelity in said third mode than in said first mode.

18. A method of operating a capacitive touch screen configured to sense in a sensing region, said method comprising:

operating in a first mode, said first mode comprising interference sensing at a first level and input sensing; and

switching to operating in a second mode in response to;

interference measured while in said first mode satisfying an interference condition; and

a determination that input is in said sensing region,

wherein, interference sensing while in said first mode is performed during a non-display update time, and while in said second mode, interference sensing is either not performed or else performed at a second level that is lower in fidelity than said first level.

19. The method as recited in claim 18, further comprising:

exiting said second mode in response to a second determination, said second determination comprising that no input is sensed in said sensing region.

20. The method as recited in claim 18, further comprising:

entering said first mode in response to a second determination, said second determination comprising no input being sensed in said sensing region for a predetermined period.

21. The method as recited in claim 18, further comprising:

entering said first mode in response to experiencing signal corruption while in said second mode.

22. The method as recited in claim 18, further comprising:

entering a third mode of operation in response to a second determination, said second determination comprising that no input has been sensed in said sensing region for a predetermined period, wherein input sensing is performed at a lower fidelity in said third mode than in said second mode.

23. The method as recited in claim 18, wherein said operating in a first mode comprising interference sensing at a first rate comprises:

performing said interference sensing at said first level with transmitter electrodes of said capacitive touch screen in a non-transmitting state.