Reducing ion-migration and corrosion in electrodes

1. A processing system for an input device comprising:

a sensor module comprising sensor circuitry, the sensor module coupled to transmitter electrodes, receiver electrodes, and a shield electrode, the sensor module configured for:

transmitting transmitter signals with the transmitter electrodes;

receiving resulting signals with the receiver electrodes, the resulting signals comprising effects corresponding to the transmitter signals; and

transitioning the shield electrode from a first voltage to a second voltage during a non-sensing time period; and

a determination module configured for determining positional information for an input object based at least in part on the resulting signals.

2. The processing system of claim 1 , wherein the sensor module is further configured for modulating the second voltage during the non-sensing time period.

3. The processing system of claim 1 , wherein the non-sensing time period occurs between at least one of capacitive frames, transmitter signal cycles, and transmitter signal bursts.

4. The processing system of claim 1 , wherein the sensor module is further configured for driving the shield electrode with a varying voltage during the non-sensing time period and driving the shield electrode with a substantially constant voltage during a sensing time period.

5. The processing system of claim 1 , wherein the sensor module is further configured for driving the shield electrode with a first substantially constant voltage during a sensing time period and driving the shield electrode with a second substantially constant voltage during the non-sensing time period, wherein the first and second substantially constant voltages are different.

6. The processing system of claim 1 , wherein the shield electrode and at least one receiver electrode are driven in a substantially similar manner during the non-sensing time period.

7. The processing system of claim 1 , wherein at least one receiver electrode is driven at a third voltage during a sensing time period, wherein the first voltage is different than the third voltage, and the second voltage is substantially equal to the third voltage.

8. The processing system of claim 1 , wherein at least one receiver electrode is driven at a third voltage during a sensing time period, wherein the first voltage is different than the third voltage, and the second voltage is different than the third voltage.

9. An input device comprising:

transmitter electrodes;

receiver electrodes;

a shield electrode;

a sensor module comprising sensor circuitry, the sensor module coupled to the transmitter electrodes, the receiver electrodes, and the shield electrode, the sensor module configured to:

transmit transmitter signals with the transmitter electrodes;

receive resulting signals with the receiver electrodes, the resulting signals comprising effects corresponding to the transmitter signals; and

transition the shield electrode from a first voltage to a second voltage during a non-sensing time period; and

a determination module configured to determine positional information for an input object based at least in part on the resulting signals.

10. The input device of claim 9 , wherein the sensor module is further configured to modulate the second voltage during the non-sensing time period.

11. The input device of claim 9 , wherein the shield electrode comprises an electrostatic discharge ring.

12. The input device of claim 9 , wherein the transmitter electrodes comprise one or more common electrodes.

13. The input device of claim 12 , wherein the capacitive sensing device is integrated with a display device, wherein the sensor module is further configured to drive one or more of the common electrodes to update the display device.

14. The input device of claim 9 , further comprising a display device stacked with the receiver electrodes.

15. A method of capacitive sensing with an input device having a sensor module and a determination module, the sensor module comprising sensor circuitry and coupled to transmitter electrodes, receiver electrodes, and a shield electrode, the method comprising:

transmitting transmitter signals with the transmitter electrodes during a sensing time period;

receiving resulting signals with the receiver electrodes, the resulting signals comprising effects corresponding to the transmitter signals;

driving the shield electrode with a first voltage during the sensing time period and a second voltage during a non-sensing time period;

transitioning the shield electrode from the first voltage to the second voltage during the non-sensing time period and

determining positional information for an input object based at least in part on the resulting signals.

16. The method of claim 15 , wherein driving the shield electrode with the second voltage comprises modulating the second voltage during the non-sensing time period.

17. The method of claim 16 , wherein driving the shield electrode with the first voltage comprises driving the shield electrode with a substantially constant voltage during the sensing time period.

18. The method of claim 15 , wherein driving the shield electrode with the second voltage occurs between at least one of capacitive frames, transmitter signal cycles, and transmitter signal bursts.

19. The method of claim 15 , wherein the first and second voltages are substantially constant and different.

20. The method of claim 15 , further comprising driving the transmitter electrodes with a voltage that updates a display.