Differential proximity sensing and side detection for an electronic device

1. An electronic device, comprising:

a housing;

a first capacitive proximity sensor on a front of the electronic device included in the housing; a second capacitive proximity sensor on a back of the electronic device included in the housing, the second capacitive proximity sensor employing a near field communication (NFC) loop antenna conductor as a capacitive sensing surface and including at least one blocking coil configured to separate NFC sensing circuitry of the electronic device from capacitive proximity touch sensing circuitry of the electronic device; and

an open loop conductor surrounding the NFC loop antenna conductor and in close proximity to the NFC loop antenna conductor,

wherein the electronic device is configured to:

monitor a signal produced by the first capacitive proximity sensor; monitor a signal produced by the second capacitive proximity sensor;

compare the signal produced by the first capacitive proximity sensor with the signal produced by the second capacitive proximity sensor; and

based on the comparison, determine a differential amount of change between the signal produced by the first capacitive proximity sensor relative to the signal produced by the second capacitive proximity sensor to determine an orientation of the electronic device.

2. The electronic device of claim 1 , further comprising a third capacitive proximity sensor on a side of the electronic device included in the housing.

3. The electronic device claimed in claim 2 , wherein capacitive proximity gain or sensitivity of the first capacitive proximity sensor and the second capacitive proximity sensor is adaptively increased based on whether the third capacitive proximity sensor detects a touch on the side of the electronic device.

4. The electronic device claimed in claim 1 , wherein the electronic device is configured to monitor directional polarity signal change between the first capacitive proximity sensor and the second capacitive proximity sensor.

5. The electronic device claimed in claim 1 , further comprising a chassis ground loop surrounding the open loop conductor and the NFC loop antenna conductor.

6. The electronic device claimed in claim 1 , further comprising a driven signaling open loop surrounding the NFC loop antenna conductor and a sensing signaling open loop surrounding the NFC loop antenna conductor.

7. The electronic device claimed in claim 1 , further comprising capacitive sensing elements within the NFC loop antenna conductor.

8. The electronic device claimed in claim 1 , wherein the first capacitive proximity sensor comprises a capacitive touchscreen for the electronic device.

9. A method performed by an electronic device, the method comprising:

monitoring a signal produced by a motion sensor within a housing of an electronic device;

monitoring a signal produced by a first capacitive proximity sensor on a front of the electronic device included in the housing;

monitoring a signal produced by a second capacitive proximity sensor on a back of the electronic device included in the housing;

monitoring a signal produced by a third capacitive proximity sensor on a side of the electronic device;

comparing the signal produced by the first capacitive proximity sensor and the signal produced by the second capacitive proximity sensor;

based on the comparing, determining a differential amount of change between the signal produced by the first capacitive proximity sensor relative to the signal produced by the second capacitive proximity sensor;

determining whether the electronic device is in a pocket of a user based on:

the determined differential amount of change; and

a positional orientation of the electronic device based on the signal produced by the motion sensor; and

adaptively increasing capacitive proximity gain or sensitivity of the first capacitive proximity sensor and the second capacitive proximity sensor based on whether the third capacitive proximity sensor detects a perimeter touch.

10. The method according to claim 9 wherein, adaptively increasing capacitive proximity gain or sensitivity of the first capacitive proximity sensor and the second capacitive proximity sensor is further based on whether the signal produced by the motion sensor indicates motion of the electronic device.

11. The method according to claim 9 further comprising:

monitoring directional polarity signal change between the first capacitive proximity sensor and the second capacitive proximity sensor.

12. An apparatus practicing the method of claim 9 .

13. An electronic device, comprising:

a housing;

a first capacitive proximity sensor on a front of the electronic device included in the housing;

a second capacitive proximity sensor on a back of the electronic device included in the housing, the second capacitive proximity sensor comprising an impedance matching circuit including a near field communication (NFC) loop; and

an open loop conductor surrounding the NFC loop and in close proximity to the NFC loop,

wherein the electronic device is configured to:

monitor a signal produced by the first capacitive proximity sensor;

monitor a signal produced by the second capacitive proximity sensor;

compare the signal produced by the first capacitive proximity sensor with the signal produced by the second capacitive proximity sensor;

based on the comparison, determine a differential amount of change between the signal produced by the first capacitive proximity sensor relative to the signal produced by the second capacitive proximity sensor; and

determine whether the front of the electronic device is in a user's pocket based on the differential amount of change.

14. The electronic device of claim 13 , further comprising a third capacitive proximity sensor on a side of the electronic device included in the housing.

15. The electronic device claimed in claim 14 , wherein capacitive proximity gain or sensitivity of the first capacitive proximity sensor and the second capacitive proximity sensor is adaptively increased based on whether the third capacitive proximity sensor detects a touch on the side of the electronic device.