Dynamic cross-talk mitigation for integrated touch screens

• US 9,310,917 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
• Application Number:
  US13/844,349
• Publication Number:
  US 20140267087A1
• Time in Patent Office: 1,124 Days
• Field of Search: 345/76, 345/78, 345 82- 83, 345/214, 345/208, 315/169.3
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• 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 3/0443 using a single layer of sensing electrodes

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

a plurality of signal generators, at least one of the plurality of signal generators configured to generate a first stimulation signal and at least one of the plurality of signal generators configured to generate a second stimulation signal;

a plurality of first circuit elements configured to detect a touch input on the touch input device;

a plurality of second circuit elements, the plurality of second circuit elements located proximal to the plurality of first circuit elements; and

a processor capable of;

performing a first scan of the touch input device comprising;

driving the first circuit elements with the first stimulation signal and sensing a first corresponding sense signal;

while driving the first circuit elements with the first stimulation signal and sensing the first corresponding sense signal, driving the second circuit elements with the second stimulation signal; and

adjusting a demodulation phase of a demodulation signal for demodulating the first corresponding sense signal; and

after the first scan, performing a second scan of the touch input device comprising;

driving the first circuit elements with the first stimulation signal and sensing a second corresponding sense signal;

while driving the first circuit elements with the first stimulation signal and sensing the second corresponding sense signal, driving the second circuit elements with the second stimulation signal; and

maintaining the demodulation phase of the demodulation signal for demodulating the second corresponding sense signal.

2. The touch input device of claim 1, wherein driving the second circuit elements with the second stimulation signal includes dithering a parameter of the plurality of second circuit elements.

3. The touch input device of claim 2, wherein dithering the parameter of the plurality of second circuit elements further includes dithering an effective resistance of the circuit element.

4. The touch input device of claim 3, wherein the plurality of second circuit elements include a gate line of a display.

5. The touch input device of claim 4, wherein dithering the effective resistance of the gate line includes dithering a resistance associated with a reservoir capacitor of the gate line.

6. The touch input device of claim 1, wherein the processor is further caused to correct a touch image of the touch input device based on a change in the detected touch signal caused by driving the second circuit elements with the second stimulation signal.

7. The touch input device of claim 1, wherein the first stimulation signal and the second stimulation signal are independently adjustable.

8. 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 first circuit elements configured to detect a touch input on the touch sensor panel with a first stimulation signal and sensing a first corresponding sense signal on the touch sensor panel;

while driving the first circuit elements with the first stimulation signal and sensing the first corresponding sense signal on the touch sensor panel, driving second circuit elements located proximal to the touch sensor panel with the second stimulation signal; and

adjusting a demodulation phase of a demodulation signal for demodulating the first corresponding sense signal; and

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

driving the first circuit elements with the first stimulation signal and sensing a second corresponding sense signal on the touch sensor panel;

while driving the first circuit elements with the first stimulation signal and sensing the second corresponding sense signal on the touch sensor panel, driving the second circuit elements with the second stimulation signal; and

maintaining the demodulation phase of the demodulation signal for demodulating the second corresponding sense signal.

9. The method of claim 8, wherein dithering the parameter of the circuit element proximal to the touch sensor panel includes dithering an effective resistance of the circuit element.

10. The method of claim 9, wherein the circuit element includes a gate line of a display.

11. The method of claim 10, wherein dithering the effective resistance of the gate line includes dithering a resistance associated with a reservoir capacitor of the gate line.

12. The method of claim 10, wherein dithering the effective resistance of the gate line includes dithering a resistance associated with a tail TFT of the gate line.

13. The method of claim 8, further comprising dithering the parameter over a plurality of touch images, and comparing the plurality of touch images to determine the change.

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

15. The method of claim 8, wherein measuring a change in the detected touch signal caused by the dithering includes:

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.

16. The method of claim 8, 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 first circuit elements configured to detect a touch input on the touch sensor panel with a first stimulation signal and sensing a first corresponding sense signal on the touch sensor panel;

while driving the first circuit elements with the first stimulation signal and sensing the first corresponding sense signal on the touch sensor panel, driving second circuit elements located proximal to the touch sensor panel with the second stimulation signal; and

adjusting a demodulation phase of a demodulation signal for demodulating the first corresponding sense signal; and

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

driving the first circuit elements with the first stimulation signal and sensing a second corresponding sense signal on the touch sensor panel;

while driving the first circuit elements with the first stimulation signal and sensing the second corresponding sense signal on the touch sensor panel, driving the second circuit elements with the second stimulation signal; and

maintaining the demodulation phase of the demodulation signal for demodulating the second corresponding 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, further comprising dithering the parameter over a plurality of touch images, and comparing 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 measuring the change in the detected touch signal caused by the dithering includes:

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.

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

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

a plurality of signal generators, at least one of the plurality of signal generators configured to generate a first stimulation signal and at least one of the plurality of signal generators configured to generate a second stimulation signal;

a plurality of first circuit elements configured to detect a touch input on the touch input device;

a plurality of second circuit elements, the plurality of second circuit elements located proximal to the plurality of first circuit elements; and

a processor capable of;

driving the first circuit elements with the first stimulation signal;

measuring a detected touch signal;

while measuring the detected touch signal, driving the second circuit elements with the second stimulation signal;

measuring a change in the detected touch signal caused by driving the second circuit elements with the second stimulation signal;

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

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

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