Position-sensing and force detection panel
In one embodiment, a sensor includes a voltage driver operable to provide an alternating voltage and an integrator circuit. The sensor further includes a first variable resistance element coupled to a first output of the voltage driver and an input of the integrator circuit. The integrator circuit is operable to measure a parameter of the first variable resistance element over a period of time. The sensor further includes circuitry operable to determine, based on the measured parameter, an amount of force applied to a touch sensing panel.
1. An apparatus, comprising:
a control unit comprising a voltage driver and an integrator circuit, the voltage driver operable to provide an alternating voltage;
a touch sensing panel operable to communicate with the control unit;
a first variable resistance element coupled to an output of the voltage driver and an input of the integrator circuit, wherein the integrator circuit is operable to measure a parameter of the first variable resistance element over a period of time, and wherein the first variable resistance element is operable to be driven by the alternating voltage provided by the voltage driver; and
circuitry operable to determine, based on the measured parameter, an amount of force applied to a sensing area of the touch sensing panel.
2. The apparatus of claim 1 , wherein the parameter is current flowing through the first variable resistance element.
3. The apparatus of claim 1 , further comprising a bias resistance element connected in parallel with the first variable resistance element.
4. The apparatus of claim 1 , further comprising a limiting resistance element connected in series with the first variable resistance element.
5. The apparatus of claim 1 , wherein the output of the voltage driver comprises a first output and further comprising a second variable resistance element coupled with a second output of the voltage driver and the input of the integrator circuit.
6. The apparatus of claim 5 , further comprising a bias resistance element connected in parallel with the second variable resistance element.
7. The apparatus of claim 5 , further comprising a limiting resistance element connected in series with the second variable resistance element.
8. The apparatus of claim 1 , wherein the input of the integrator circuit is at a voltage between a first voltage and a second voltage of the alternating voltage provided by the voltage driver.
9. The apparatus of claim 1 , wherein the circuitry is operable to determine an amount of force applied to the sensing area using a differential measurement.
10. The apparatus of claim 1 , wherein the circuitry is further operable to determine a location in a sensing area of the touch sensing panel associated with the determined amount of force.