Input device having reduced electromagnetic interference

1. A processing system for an input device, the processing system comprising:

a driver configured to:

drive a sensor electrode with a sensing signal during a first portion of a non-display update period of a display frame, wherein the sensing signal comprises a varying voltage;

drive the sensor electrode with a first constant voltage during a first display period of the display frame and a second display period of the display frame for display updating, wherein the non-display update period occurs between the first display period and second display period; and

drive the sensor electrode with a second constant voltage during at least one of a second portion of the non-display update period and a third portion of the non-display update period, wherein the first portion of the non-display update period occurs after the second portion of the non-display update period and before the third portion of the non-display update period, and wherein the first constant voltage is different than the second constant voltage; and

a source driver configured to drive a first data line of a display panel with a third constant voltage during at least one of the second portion of the non-display update period and the third portion of the non-display update period.

2. The processing system of claim 1 , wherein the source driver is further configured to output a guard signal during the first portion of the non-display update period, wherein the guard signal mitigates capacitive coupling between the source driver and the sensor electrode.

3. The processing system of claim 2 , wherein the guard signal comprises at least one selected from the group of a frequency, phase and amplitude in common with the sensing signal.

4. The processing system of claim 1 , wherein the third constant voltage differs from the second constant voltage.

5. The processing system of claim 2 , wherein outputting the guard signal during the first portion of the non-display update period comprises outputting the guard signal onto the first data line.

6. The processing system of claim 2 , wherein the source driver is selectively coupled to the first data line during the second portion and the third portion of the non-display update period and is selectively decoupled from the first data line during the first portion of the non-display update period, and wherein the first data line is electrically floated during the first portion of the non-display update period.

7. The processing system of claim 6 , wherein the source driver is further:

selectively coupled to a second data line of the display panel during the second portion and the third portion of the non-display update period; and

selectively decoupled from the second data line during the first portion of the non-display update period, and wherein the second data line is electrically floated during the first portion of the non-display update period.

8. An input device, comprising:

a plurality of data lines of a display panel;

a plurality of sensor electrodes; and

a processing system, the processing system configured to:

drive a sensor electrode of the plurality of sensor electrodes with a sensing signal during a first portion of a non-display update period of a display frame, wherein the sensing signal comprises a varying voltage;

drive the sensor electrode with a first constant voltage during a first display period of the display frame and a second display period of the display frame for display updating, wherein the non-display update period occurs between the first display period and second display period; and

drive the sensor electrode with a second constant voltage during at least one of a second portion of the non-display update period and a third portion of the non-display update period, wherein the second constant voltage is different than the first constant voltage, and wherein the first portion of the non-display update period occurs after the second portion of the non-display update period and before the third portion of the non-display update period; and

output a guard signal during the first portion of the non-display update period, wherein the guard signal mitigates capacitive coupling between the processing system and the sensor electrode.

9. The input device of claim 8 , wherein the processing system is further configured to drive a first data line of the plurality of data lines with a third constant voltage during at least one of the second portion of the non-display update period and the third portion of the non-display update period.

10. The input device of claim 8 , wherein the guard signal comprises at least one selected from the group of a frequency, phase and amplitude in common with the sensing signal.

11. The input device of claim 9 , wherein outputting the guard signal during the first portion of the non-display update period comprises outputting the guard signal onto the first data line.

12. The input device of claim 9 , further comprising a selection mechanism configured to:

selectively couple the processing system with the first data line during the second portion and the third portion of the non-display update period; and

selectively decouple the processing system with the first data line during the first portion of the non-display update period, wherein the first data line is electrically floated during the first portion of the non-display update period.

13. The input device of claim 12 , wherein the selection mechanism is further configured to:

selectively couple the processing system with a second data line of the plurality of data lines during the second portion and the third portion of the non-display update period; and

selectively decouple the processing system with the second data line during the first portion of the non-display update period, wherein the second data line is electrically floated during the first portion of the non-display update period.

14. A method for input sensing comprising:

driving a sensor electrode with a sensing signal during a first portion of a non-display update period of a display frame, wherein the sensing signal comprises a varying voltage;

driving the sensor electrode with a first constant voltage during a first display period of the display frame and a second display period of the display frame for display updating, wherein the non-display update period occurs between the first display period and the second display period;

driving the sensor electrode with a second constant voltage during at least one of a second portion of the non-display update period and a third portion of the non-display update period, wherein the second constant voltage is different than the first constant voltage, and wherein the first portion of the non-display update period occurs after the second portion of the non-display update period and before the third portion of the non-display update period; and

driving a first data line of a display panel with a third constant voltage during at least one of the second portion of the non-display update period and the third portion of the non-display update period.

15. The method of claim 14 , further comprising outputting a guard signal during the first portion of the non-display update period, wherein the guard signal mitigates capacitive coupling between a source driver and the sensor electrode.

16. The method of claim 15 , wherein the guard signal comprises at least one selected from the group of a frequency, phase and amplitude in common with the sensing signal.

17. The method of claim 15 , wherein outputting the guard signal during the first portion of the non-display update period comprises outputting the guard signal onto the first data line.

18. The method of claim 15 , further comprising:

selectively coupling the first data line with the source driver during the second portion and the third portion of the non-display update period.

19. The method of claim 18 , further comprising:

selectively decoupling the first data line from the source driver during the first portion of the non-display update period, and wherein the first data line is electrically floated during the first portion of the non-display update period.

20. The method of claim 18 , further comprising:

selectively coupling a second data line of the display panel with the source driver during the second portion and the third portion of the non-display update period; and

selectively decoupling the second data line from the source driver during the first portion of the non-display update period, and wherein the second data line is electrically floated during the first portion of the non-display update period.