Touch sensor close detection

1 . An input device having an opened state and a closed state, the input device comprising:

a first portion comprising a touch sensor having a sensing area, wherein the touch sensor comprises:

a plurality of transmitter electrodes;

a plurality of receiver electrodes;

a second portion comprising a plurality of features;

a sensor circuit configured to:

drive the plurality of transmitter electrodes with sensing signals;

receive resulting signals from the plurality of receiver electrodes;

a processing system configured to:

generate a reference image using the sensing area of the touch sensor to image the second portion when the input device is in the closed state, wherein the reference image includes data corresponding to the plurality of features;

generate an acquired image from at least a portion of the sensing area;

compare the acquired image to the reference image; and

determine whether the input device is in the closed state based on the comparison of the acquired image to the reference image.

2 . The input device of claim 1 , wherein the sensor circuit is configured to drive the plurality of transmitter electrodes with transcapacitive sensing signals.

3 . The input device of claim 1 , wherein the plurality of features includes at least one non-functional feature and wherein the data corresponding to the plurality of features includes data corresponding the non-functional feature.

4 . The input device of claim 1 , wherein the first portion further comprises an integrated display.

5 . The input device of claim 1 , wherein the processing system is further configured to determine the input device is in the opened state.

6 . The input device of claim 1 , wherein the sensor circuit is further configured to perform forced relaxation.

7 . The input device of claim 1 , wherein the reference image is adaptive.

8 . The input device of claim 1 , wherein the processing system is further configured to:

determine a score value based on the comparison of the acquired image to the reference image;

compare the score value to a threshold; and

determine the input device is in the closed state when the score value exceeds the threshold.

9 . The input device of claim 1 , wherein the plurality of features include at least one of a keyboard, a fingerprint sensor, or a touch pad.

10 . A touch sensor having a sensing area, the touch sensor comprising:

a plurality of transmitter electrodes;

a plurality of receiver electrodes;

a sensor circuit configured to:

drive the plurality of transmitter electrodes with sensing signals;

receive resulting signals from the plurality of receiver electrodes;

a processing system configured to:

generate a reference image of at least a portion of a device using the touch sensor when the device is in a closed state, wherein the reference image includes data corresponding to a plurality of features proximate to the sensing area when the device associated with the touch sensor is in the closed state;

generate an acquired image from at least a portion of the sensing area;

compare the acquired image to the reference image; and

determine whether the device is in the closed state based on the comparison of the acquired image to the reference image.

11 . The touch sensor of claim 10 , wherein the sensor circuit is configured to drive the plurality of transmitter electrodes with transcapacitive sensing signals.

12 . The touch sensor of claim 10 , wherein the plurality of features include at least one non-functional feature and wherein the data corresponding to the plurality of features includes data corresponding the non-functional feature.

13 . The touch sensor of claim 10 , wherein the processing system is further configured to determine the device is in an opened state.

14 . The touch sensor of claim 10 , wherein the sensor circuit is further configured to perform forced relaxation.

15 . The touch sensor of claim 10 , wherein the reference image is adaptive.

16 . The touch sensor of claim 10 , wherein the plurality of features include at least one of a keyboard, a fingerprint sensor, or a touch pad.

17 . A method for determining when a device is in a closed state comprising:

driving a plurality of transmitter electrodes of a touch sensor on a first portion of the device with sensing signals;

receiving resulting signals from a plurality of receiver electrodes of the touch sensor on the first portion of the device;

generating a reference image using the touch sensor when the device is in the closed state, wherein the reference image includes data corresponding to a plurality of features of a second portion of the device proximate to the touch sensor when the device is in the closed state;

generating an acquired image from the touch sensor with the resulting signals;

comparing the acquired image to the reference image; and

determining the device is in the closed state based on the comparison of the acquired image to the reference image.

18 . The method of claim 17 , wherein driving the plurality of transmitter electrodes with the sensing signals comprises driving the plurality of transmitter electrodes with transcapacitive sensing signals.

19 . The method of claim 17 , further comprising:

determining the device is in an opened state.

20 . The method of claim 17 , further comprising:

performing forced relaxation by reestablishing a baseline.