SYSTEM AND METHOD FOR INTERFERENCE AVOIDANCE FOR A DISPLAY DEVICE COMPRISING AN INTEGRATED SENSING DEVICE

• US 20140049507A1
• Filed: 09/27/2012
• Published: 02/20/2014
• Est. Priority Date: 08/15/2012
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Shepelev, Petr, Reynolds, Joseph Kurth, Sabo, David
• Granted Patent: US 10,073,568 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

Embodiments of the invention generally provide an input device with display screens that periodically update (refresh) the screen by selectively driving electrodes corresponding to pixels in a display line. In addition to updating the display, the input device may perform capacitive sensing using the display screen as a touch area. To do this, the input device uses common electrodes for both updating the display and performing capacitive sensing, and interleaves periods of capacitive sensing between periods of updating the display lines (and pixels) based on a display frame. To avoid noise and mitigate interference during capacitive sensing, the input device may change the capacitive frame rate relative to the display frame rate based on measurements of interference. The changed capacitive frame rate may result in re-timed periods of capacitive sensing based on each display frame.

Claims

1. A processing system for a display device having an integrated capacitive sensing device, the processing system comprising:

a driver module comprising driver circuitry coupled to a plurality of common electrodes configured to be driven for display updating and capacitive sensing, wherein the driver module is configured to;

drive a first common electrode for display updating during a first display line update period of a first display frame, the first display frame occurring at a pre-determined display frame rate,

drive a second common electrode for display updating during a second display line update period of the first display frame,

drive a first common electrode set comprising at least one of the plurality of common electrodes for capacitive sensing at a capacitive frame rate during a first non-display period of the first display frame, the first non-display period occurring after the first display line update period and before the second display line update period, and the first non-display period being at least as long as the first display line update period;

operate a second common electrode set comprising at least one of the plurality of common electrodes for interference detection during a second non-display period;

a receiver module coupled to a plurality of receiver electrodes and configured to receive first resulting signals with the plurality of receiver electrodes during the first non-display period and second resulting signals during the second non-display period; and

a determination module configured to determine an interference measurement based at least in part on the second resulting signals, wherein an amount of the first non-display period which is used for capacitive sensing is adjusted based on the interference measurement.

2. The processing system of claim 1, wherein the determination module is further configured to adjust the capacitive frame rate relative to the display frame rate based on the interference measurement.

3. The processing system of claim 2, wherein the determination module configured to adjust the capacitive frame rate relative to the display frame rate is further configured to adjust a length of the first non-display period.

4. The processing system of claim 2, wherein the determination module configured to adjust the capacitive frame rate relative to the display frame rate is further configured to drive the first common electrode set for capacitive sensing during a third non-display period of the first display frame, the third non-display period occurring after the first non-display period, the first and third non-display periods comprising a capacitive frame.

5. The processing system of claim 1, wherein the determination module configured to adjust the amount of the second non-display period which is used for capacitive sensing based on the interference measurement is further configured to increase the amount of the second non-display period which is used for capacitive sensing.

6. The processing system of claim 1, wherein the determination module configured to adjust the amount of the second non-display period which is used for capacitive sensing based on the interference measurement is further configured to decrease the amount of the second non-display period which is used for capacitive sensing.

7. The processing system of claim 1, wherein the driver module configured to operate the second common electrode set is further configured to one of (i) drive the second common electrode set with a substantially constant voltage and (ii) electrically float the second common electrode set.

8. The processing system of claim 1, wherein the determination module configured to adjust the amount of the second non-display period which is used for capacitive sensing is further configured to shift from driving the first common electrode set with a first transmitter signal having a first frequency to driving the first common electrode set with a second transmitter signal having a second frequency, wherein the first frequency is different from the second frequency.

9. A processing system for a display device having an integrated capacitive sensing device, the processing system comprising:

a driver module comprising driver circuitry coupled to a plurality of common electrodes configured to be driven for display updating and capacitive sensing, wherein the driver module is configured to;

drive a first common electrode for display updating during a first display line update period of a first display frame, the first display frame occurring at a display frame rate,

drive a second common electrode for display updating during a second display line update period of the first display frame,

drive a first common electrode set comprising at least one of the plurality of common electrodes for capacitive sensing during a first non-display period at a capacitive frame rate, wherein the first non-display period occurs after the first display line update period and before the second display line update period, and the first non-display period being at least as long as the first display line update period,

operate a second common electrode set comprising at least one of the plurality of common electrodes for interference detection during a second non-display period;

a receiver module coupled to a plurality of receiver electrodes and configured to receive first resulting signals with the plurality of receiver electrodes during the first non-display period and second resulting signals during the second non-display period; and

a determination module configured to determine an interference measurement based at least in part on the second resulting signals, wherein the determination module is further configured to adjust an amount of capacitive frames per display frame based on the interference measurement.

10. The processing system of claim 9, wherein the determination module configured to adjust the amount of capacitive frames per display frame is further configured to adjust a length of the first non-display period.

11. The processing system of claim 9, wherein the determination module configured to adjust the amount of capacitive frames per display frame is further configured to drive the first common electrode set for capacitive sensing during the third non-display period of the first display frame, the third non-display period occurring after the first non-display period, the first and third non-display periods comprising a capacitive frame.

12. The processing system of claim 9, wherein the determination module configured to adjust the amount of capacitive frames per display frame is further configured to increase the amount of the second non-display period which is used for capacitive sensing.

13. The processing system of claim 9, wherein the driver module configured to operate the second common electrode set is further configured to one of (i) drive the first common electrode set with a substantially constant voltage and (ii) electrically float the first common electrode set.

14. The processing system of claim 9, wherein the determination module configured to adjust the amount of capacitive frames per display frame is further configured to shift from driving the first common electrode set with a first transmitter signal having a first frequency to driving the first common electrode set with a second transmitter signal having a second frequency, wherein the first frequency is different from the second frequency.

15. A method for operating a display device having an integrated capacitive sensing device, the method comprising:

driving, a first common electrode of a plurality of common electrodes for display updating during a first display line update period of a first display frame, the first display frame occurring at a display frame rate, wherein the plurality of common electrodes are configured for display updating and capacitive sensing;

driving a second common electrode of the plurality of common electrodes for display updating during a second display line update period of the first display frame;

operating a first common electrode set comprising at least one of the plurality of common electrodes for interference detection;

receiving first resulting signals from a plurality of receiver electrodes while operating the first common electrode set for interference detection;

determining an interference measurement based at least in part on the first resulting signals; and

adjusting an amount of a first non-display period which is used for capacitive sensing based on the interference measurement.

driving a second first common electrode set comprising at least one of the plurality of common electrodes for capacitive sensing during the amount of the first non-display period of the first display frame at a capacitive frame rate, the first non-display period occurring after the first display line update period and before the second display line update period, and the first non-display period being at least as long as the first display line update period.

16. The method of claim 15, wherein operating the second common electrode set for interference detection comprises one of driving the second common electrode set with a substantially constant voltage and electrically floating the second common electrode set.

17. The method of claim 15, the method further comprising adjusting the capacitive frame rate relative to the display frame rate based on the interference measurement.

18. The method of claim 15, wherein adjusting an amount of the first non-display period which is used for capacitive sensing based on the interference measurement comprises one of increasing the amount of the first non-display period which is used for capacitive sensing and decreasing the amount of the first non-display period which is used for capacitive sensing.

19. The method of claim 17, wherein adjusting the capacitive frame rate relative to the display frame rate based on the interference measurement comprising one of increasing the capacitive frame rate relative to the display frame rate and decreasing the capacitive frame rate relative to the display frame rate.

20. The method of claim 15, wherein adjusting an amount of the first non-display period which is used for capacitive sensing based on the interference measurement comprises shifting from driving the first common electrode set with a first transmitter signal having a first frequency to driving the first common electrode set with a second transmitter signal having a second frequency, wherein the first frequency is different from the second frequency.