Dynamic cross-talk mitigation for integrated touch screens

• US 9,310,931 B2
• Filed: 03/15/2013
• Issued: 04/12/2016
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Yousefpor, Marduke, Krah, Christoph Horst, White, Kevin J.
• Primary Examiner(s): ABDIN, SHAHEDA A
• Application Number:
  US13/844,171
• Publication Number:
  US 20140267086A1
• Time in Patent Office: 1,124 Days
• Field of Search: 345/76, 345/78, 345 82- 83, 345/214, 345/208, 345/211, 315/169.3
• US Class Current: 1/1
• CPC Class Codes: G06F 3/04184 Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• 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
• CPC Class Codes: G06F 3/0448 Details of the electrode shape, e.g. for enhancing the detection of touches, for generating specific electric field shapes, for enhancing display quality

Abstract

A touch input device configured to mitigate the effects of dynamic cross talk noise is provided. The touch input device can dither an effective resistance of a plurality of gate lines proximal to the touch sensor panel in order to determine if a phase of a touch signal demodulator needs to be adjusted.

Claims

1. A method of dynamically reducing the effect of noise on a touch sensor panel, the method comprising:

performing a first scan of the touch sensor panel comprising;

driving a drive electrode, sensing a corresponding sense electrode and demodulating a sense signal corresponding to the sense electrode with a demodulation signal;

while driving the drive electrode and sensing the sense electrode, dithering a parameter of a circuit element proximal to the touch sensor panel; and

after dithering the parameter, adjusting a phase of the demodulation signal for demodulating the sense signal; and

after the first scan, performing a second scan of the touch sensor panel comprising;

driving the drive electrode, sensing the corresponding sense electrode and demodulating the sense signal with the demodulation signal;

while driving the drive electrode and sensing the sense electrode, dithering the parameter of the circuit element proximal to the touch sensor panel; and

after dithering the parameter, maintaining the phase of the demodulation signal for demodulating the sense signal.

2. The method of claim 1, wherein dithering the parameter of the circuit element proximal to the touch sensor panel includes dithering an effective resistance of the circuit element.

3. The method of claim 2, wherein the circuit element includes a gate line of a display.

4. The method of claim 3, wherein dithering the effective resistance of the gate line includes dithering a resistance associated with a reservoir capacitor of the gate line.

5. The method of claim 3, wherein dithering the effective resistance of the gate line includes dithering a resistance associated with a tail TFT of the gate line.

6. The method of claim 1, further comprising dithering the parameter over a plurality of touch images, and comparing the plurality of touch images to determine the change.

7. The method of claim 1, further comprising:

acquiring a touch image;

dithering the parameter at a fixed frequency during the acquisition of the touch image;

and

filtering the acquired touch image so as to isolate a portion of the acquired touch image correlated to the dithering of the parameter.

8. The method of claim 1, wherein the demodulation phase is adjusted such that the phase is orthogonal to a phase of cross-talk noise.

9. A touch input device configured to reduce the effects of noise, the touch input device comprising:

a touch sensor panel;

a processor capable of;

performing a first scan of the touch sensor panel comprising;

driving a drive electrode, sensing a corresponding sense electrode and demodulating a sense signal corresponding to the sense electrode with a demodulation signal;

while driving the drive electrode and sensing the sense electrode, dithering a parameter of a circuit element proximal to the touch sensor panel; and

after dithering the parameter, adjusting a phase of the demodulation signal for demodulating the sense signal; and

after the first scan, performing a second scan of the touch sensor panel comprising;

driving the drive electrode, sensing the sense electrode and demodulating the sense signal with the demodulation signal;

while driving the drive electrode and sensing the sense electrode, dithering the parameter of the circuit element proximal to the touch sensor panel; and

after dithering the parameter, maintaining the phase of the demodulation signal for demodulating the sense signal.

10. The touch input device of claim 9, wherein dithering the parameter of the circuit element proximal to the touch sensor panel includes dithering an effective resistance of the circuit element.

11. The touch input device of claim 10, wherein the circuit element includes a gate line of a display.

12. The touch input device of claim 11, wherein dithering the effective resistance of the gate line includes dithering a resistance associated with a reservoir capacitor of the gate line.

13. The touch input device of claim 11, wherein dithering the effective resistance of the gate line includes dithering a resistance associated with a tail TFT of the gate line.

14. The touch input device of claim 9, wherein the processor is further capable of dithering the parameter over a plurality of touch images, and comparing the plurality of touch images to determine the change in the touch signal.

15. The touch input device of claim 9, wherein the processor is further capable of:

acquiring a touch image;

dithering the parameter at a fixed frequency during the acquisition of the touch image; and

filtering the touch image so as to isolate a portion of the acquired touch image correlated to the dithering of the parameter.

16. The touch input device of claim 9, wherein the demodulation phase is adjusted such that the phase is orthogonal to a phase of cross-talk noise.

17. A non-transitory computer readable storage medium having stored thereon a set of instructions for reducing the effects of noise in a touch sensor panel, that when executed by a processor causes the processor to:

perform a first scan of the touch sensor panel comprising;

driving a drive electrode, sensing a corresponding sense electrode and demodulating a sense signal corresponding to the sense electrode with a demodulation signal;

while driving the drive electrode and sensing the sense electrode, dithering a parameter of a circuit element proximal to the touch sensor panel; and

after dithering the parameter, adjusting a phase of the demodulation signal for demodulating the sense signal; and

after the first scan, perform a second scan of the touch sensor panel comprising;

driving the drive electrode, sensing the sense electrode and demodulating the sense signal with the demodulation signal;

while driving the drive electrode and sensing the sense electrode, dithering the parameter of the circuit element proximal to the touch sensor panel; and

after dithering the parameter, maintaining the phase of the demodulation signal for demodulating the sense signal.

18. The non-transitory computer readable storage medium of claim 17, wherein dithering the parameter of the circuit element proximal to the touch sensor panel includes dithering an effective resistance of the circuit element.

19. The non-transitory computer readable storage medium of claim 18, wherein the circuit element includes a gate line of a display.

20. The non-transitory computer readable storage medium of claim 19, wherein dithering the effective resistance of the gate line includes dithering a resistance associated with a reservoir capacitor of the gate line.

21. The non-transitory computer readable storage medium of claim 19, wherein dithering the effective resistance of the gate line includes dithering a resistance associated with a tail TFT of the gate line.

22. The non-transitory computer readable storage medium of claim 17, wherein the instructions further cause the processor to dither the parameter over a plurality of touch images, and compare the plurality of touch images to determine the change in the touch signal.

23. The non-transitory computer readable storage medium of claim 17, wherein the instructions further cause the processor to:

acquire a touch image

dither the parameter at a fixed frequency during the acquisition of the touch image;

and

filter the touch image so as to isolate a portion of the acquired touch image correlated to the dithering of the parameter.

24. The non-transitory computer readable storage medium of claim 17, wherein the phase of the local oscillator is adjusted such that the phase is orthogonal to a phase of cross-talk noise.

25. A touch input device configured to reduce the effects of noise, the touch input device comprising:

a touch sensor panel; and

a processor capable of;

measuring a detected touch signal on the touch sensor panel;

while measuring the detected touch signal, dithering a parameter of a circuit element proximal to the touch sensor panel;

measuring a change in the detected touch signal caused by the dithering, the measurement including demodulating the detected touch signal using a demodulation signal having a demodulation phase;

comparing the change in the detected touch signal caused by the dithering to a pre-determined threshold;

in accordance with a determination that the change in the detected touch signal caused by the dithering is above the pre-determined threshold, adjusting the demodulation phase of the demodulation signal for demodulating the detected touch signal; and

in accordance with a determination that the change in the detected touch signal caused by the dithering is below the pre-determined threshold, maintaining the demodulation phase of the demodulation signal for demodulating the detected touch signal.