Compensation for air gap in an input device

1. A processing system for a display device integrated with a capacitive sensing device comprising:

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

a receiver module coupled to a plurality of receiver electrodes and configured for receiving resulting signals with the receiver electrodes when the plurality of common electrodes are driven for capacitive sensing by the driver module; and

a determination module configured for:

determining a first capacitive image based on the resulting signals;

comparing the first capacitive image to a baseline capacitive image to determine a delta capacitive image;

comparing the delta capacitive image to one or more saturation capacitance values;

in response to the comparing, replacing the one or more saturation capacitance values with one or more capacitance values from the delta capacitive image; and

determining one or more calibration values based on the one or more saturation capacitance values, wherein the one or more calibration values calibrate for an air gap defined between a cover lens of a display device integrated with a capacitive sensing device and the plurality of common electrodes.

2. The processing system of claim 1 , wherein determining the one or more calibration values comprises fitting a plane to the one or more saturation capacitance values.

3. The processing system of claim 1 , wherein determining the first capacitive image comprises instructing a user to place an input object on one or more predetermined input locations.

4. The processing system of claim 3 , wherein the one or more predetermined input locations comprise at least one of:

at least three input areas;

one or more one-dimensional sliding areas;

one or more zero-dimensional input locations; and

a plurality of input locations along the perimeter of the capacitive sensing device.

5. The processing system of claim 1 , wherein the determination module is further configured for determining the one or more calibration values based on at least one of:

a predetermined number of capacitive images, wherein at least one of the predetermined number capacitive images comprises effects due to an input object; and

capacitive images associated with one or more predetermined input areas.

6. The processing system of claim 1 , wherein each of the one or more saturation capacitance values is associated with a sensing region location.

7. The processing system of claim 1 , wherein the determination module is further configured for determining that the one or more saturation capacitance values should not be replaced with the one or more capacitance values because the one or more capacitance values exceed a threshold value.

8. The processing system of claim 1 , wherein the determination module is further configured for:

determining a second capacitive image based on the resulting signals; and

modifying the second capacitive image based on the one or more calibration values.

9. The processing system of claim 1 , wherein the determination module is further configured for:

determining a duration of time for which an input object has occupied an input sensing region; and

determining that the duration of time exceeds a threshold value; and

based on the duration of time exceeding the threshold value, determining that a third capacitive image should not be used to determine the one or more calibration values.

10. A display device integrated with a capacitive sensing device comprising:

a plurality of common electrodes;

a plurality of receiver electrodes;

a processing system coupled to the plurality of common electrodes and the plurality of receiver electrodes, the processing system configured to:

drive the plurality of common electrodes for display updating and capacitive sensing;

receive resulting signals with the receiver electrodes when the plurality of common electrodes are driven for capacitive sensing;

determine a first capacitive image based on the resulting signals;

compare the first capacitive image to a baseline capacitive image to determine a delta capacitive image;

compare the delta capacitive image to one or more saturation capacitance values;

in response to the comparison, replace the one or more saturation capacitance values with one or more capacitance values from the delta capacitive image; and

determine one or more calibration values based on the one or more saturation capacitance values; and

a cover lens disposed over the plurality of common electrodes, wherein the one or more calibration values calibrate for an air gap defined between the cover lens and the plurality of common electrodes.

11. The display device of claim 10 , wherein the processing system is configured to determine the one or more calibration values by fitting a plane to the one or more saturation capacitance values.

12. The display device of claim 10 , wherein the processing system is configured to determine the first capacitive image by instructing a user to place an input object on one or more predetermined sensing region locations, the one or more predetermined sensing region locations comprising at least one of:

at least three input areas;

one or more one-dimensional sliding areas;

one or more zero-dimensional sensing region locations; and

a plurality of sensing region locations along the perimeter of the capacitive sensing device.

13. The display device of claim 10 , wherein the processing system is further configured to determine the one or more calibration values based on at least one of:

a predetermined number of capacitive images, wherein at least one of the predetermined number capacitive images comprises effects due to an input object; and

capacitive images associated with one or more predetermined input areas.

14. The display device of claim 10 , wherein each of the one or more saturation capacitance values is associated with a sensing region location.

15. A method of capacitive sensing with a display device integrated with a capacitive sensing device having a plurality of common electrodes and a plurality of receiver electrodes, the method comprising:

driving the plurality of common electrodes for display updating and capacitive sensing;

receiving resulting signals from the receiver electrodes when the plurality of common electrodes are driven for capacitive sensing;

determining a first capacitive image based on the resulting signals;

comparing the first capacitive image to a baseline capacitive image to determine a delta capacitive image;

comparing the delta capacitive image to one or more saturation capacitance values;

in response to the comparing, replacing the one or more saturation capacitance values with one or more capacitance values from the delta capacitive image; and

determining one or more calibration values based on the one or more saturation capacitance values,

wherein the one or more calibration values calibrate for an air gap defined between a cover lens of a display device integrated with a capacitive sensing device and the plurality of common electrodes.

16. The method of claim 15 , wherein determining the one or more calibration values comprises fitting a plane to the one or more saturation capacitance values.

17. The method of claim 15 , wherein determining the first capacitive image comprises instructing a user to place an input object on one or more predetermined sensing region locations, the one or more predetermined sensing region locations comprising at least one of:

at least three input areas;

one or more one-dimensional sliding areas;

one or more zero-dimensional sensing region locations; and

a plurality of sensing region locations along the perimeter of the capacitive sensing device.

18. The method of claim 15 , wherein determining the one or more calibration values based on at least one of:

a predetermined number of capacitive images, wherein at least one of the predetermined number capacitive images comprises effects due to an input object; and

capacitive images associated with one or more predetermined input areas.

19. The method of claim 15 , wherein each of the one or more saturation capacitance values is associated with a sensing region location.

20. The method of claim 15 , further comprising:

determining a duration of time for which an input object has occupied an input sensing region; and

determining that the duration of time exceeds a threshold value; and

based on the duration of time exceeding the threshold value, determining that a third capacitive image should not be used to determine the one or more calibration values.