Common-mode hover detection
In one embodiment, a method includes substantially simultaneously applying a pre-determined voltage to a conductive layer and to one or more electrodes of a touch sensor. The conductive layer is spatially separated from the electrodes by at least a thickness of a substrate. The method also includes determining a difference between a measurement current of one or more of the electrodes and a reference value; and determining whether a proximity or touch input to the touch sensor has occurred based at least in part on the difference.
1. A method comprising:
substantially simultaneously applying a pre-determined voltage to a conductive layer and to one or more electrodes of a touch sensor, the conductive layer disposed around at least two sides of a printed-circuit board (PCB), the one or more electrodes situated in a first plane, the conductive layer and the PCB situated in a second plane different than the first plane;
determining a difference between a measurement current of one or more of the electrodes and a reference value; and
determining whether a proximity or touch input to the touch sensor has occurred based at least in part on the difference.
2. The method of claim 1 , wherein the determination of the difference comprises integrating the measurement current of one or more of the electrodes.
3. The method of claim 1 , wherein the pre-determined voltage comprises a voltage having a square-wave waveform.
4. The method of claim 1 , further comprising amplifying the measurement current.
5. The method of claim 1 , wherein the application of the pre-determined voltage comprises applying the pre-determined voltage to an input of an integrator circuit.
6. The method of claim 1 , wherein the conductive layer is annular shaped and surrounds the PCB.
7. The method of claim 6 , wherein a device housing the PCB is held by a user.
8. A computer-readable non-transitory storage medium embodying instructions configured, when executed, to:
substantially simultaneously apply a pre-determined voltage to a conductive layer and to one or more electrodes of a touch sensor, the conductive layer disposed around at least two sides of a printed-circuit board (PCB), the one or more electrodes situated in a first plane, the conductive layer and the PCB situated in a second plane different than the first plane;
determine a difference between a measurement current of one or more of the electrodes and a reference value; and
determine whether a proximity or touch input to the touch sensor has occurred based at least in part on the difference.
9. The medium of claim 8 , wherein the instructions are further configured to integrate the measurement current of one or more of the electrodes.
10. The medium of claim 8 , wherein the pre-determined voltage comprises a voltage having a square-wave waveform.
11. The medium of claim 8 , wherein the instructions are further configured to amplify the measurement current.
12. The medium of claim 8 , wherein the instructions are further configured to apply the pre-determined voltage to an input of an integrator circuit.
13. The medium of claim 8 , wherein the conductive layer is annular shaped and surrounds the PCB.
14. The medium of claim 13 , wherein a device housing the PCB is held by a user.
15. A device comprising:
a measurement circuit;
a touch sensor; and
a computer-readable non-transitory storage medium coupled to the measurement circuit and embodying instructions configured, when executed, to:
substantially simultaneously apply a pre-determined voltage to a conductive layer and to one or more electrodes of the touch sensor, the conductive layer disposed around at least two sides of a printed-circuit board (PCB), the one or more electrodes situated in a first plane, the conductive layer and the PCB situated in a second plane different than the first plane;
determine a difference between a measurement current of one or more of the electrodes and a reference value; and
determine whether a proximity or touch input to the touch sensor has occurred based at least in part on the difference.
16. The device of claim 15 , wherein the pre-determined voltage comprises a voltage having a square-wave waveform.
17. The device of claim 15 , wherein the instructions are further configured to apply the pre-determined voltage to an input of an integrator circuit.