False triggering prevention in a resonant phase sensing system
A system may include a resistive-inductive-capacitive sensor, a measurement circuit communicatively coupled to the resistive-inductive-capacitive sensor and configured to at a plurality of periodic intervals, measure phase information associated with the resistive-inductive-capacitive sensor and based on the phase information, determine a displacement of a mechanical member relative to the resistive-inductive-capacitive sensor. The system may also include a driver configured to drive the resistive-inductive-capacitive sensor at a driving frequency and a driving amplitude, wherein at least one of the driving frequency and the driving amplitude varies among the plurality of periodic intervals.
1. A system comprising:
a resistive-inductive-capacitive sensor;
a measurement circuit communicatively coupled to the resistive-inductive-capacitive sensor and configured to:
at a plurality of periodic intervals, measure phase information associated with the resistive-inductive-capacitive sensor; and
based on the phase information, determine a displacement of a mechanical member relative to the resistive-inductive-capacitive sensor; and
a driver configured to drive the resistive-inductive-capacitive sensor at a driving frequency and a driving amplitude, wherein at least one of the driving frequency and the driving amplitude varies among the plurality of periodic intervals.
2. The system of claim 1 , wherein the driver is configured to vary at least one of the driving frequency and the driving amplitude among the plurality of periodic intervals in at least one of a sequential manner, a random manner, a pseudo-random manner, and a deterministic manner.
3. The system of claim 1 , further comprising a voltage-controlled oscillator to set the driving frequency.
4. The system of claim 3 , wherein a tuning voltage of the voltage-controlled oscillator is used to set the driving frequency.
5. The system of claim 3 , wherein the voltage-controlled oscillator is configured to be modulated in accordance with a frequency modulation or a phase modulation in order to set the driving frequency.
6. The system of claim 1 , further comprising a plurality of voltage-controlled oscillators each having a different oscillation frequency, and wherein a selection of a voltage-controlled oscillator from the plurality of voltage-controlled oscillators is used to set the driving frequency.
7. The system of claim 1 , further comprising a passive reactive circuit element external to the resistive-inductive-capacitive sensor, wherein a resonant frequency of the resistive-inductive-capacitive sensor is modified responsive to varying of the driving frequency by modifying a reactance of the passive reactive circuit element.
8. The system of claim 1 , further comprising a control circuit configured to blank at least one of a clock or data associated with the measurement circuit while the driving frequency is in transition between two frequencies.
9. The system of claim 1 , wherein the measurement circuit is further configured to determine an occurrence of a physical interaction associated with a human-machine interface associated with the mechanical member based on the phase information.
10. The system of claim 9 , further comprising a processing circuit configured to process the phase information and data from at least one other sensor to determine the occurrence of the physical interaction.
11. The system of claim 10 , wherein the at least one other sensor comprises one or more of an accelerometer, a gyroscope, a touch sensor, a proximity sensor, a temperature sensor, and an ambient light sensor.
12. The system of claim 1 , wherein the measurement circuit comprises a coherent incident/quadrature detector to track a resonant frequency of the resistive-inductive-capacitive sensor and the measurement circuit is configured to measure the phase information using the coherent incident/quadrature detector.
13. The system of claim 1 , wherein the measurement circuit is further configured to:
at the plurality of periodic intervals, measure amplitude information associated with the resistive-inductive-capacitive sensor;
compare the driving amplitude of an interval of the plurality of periodic intervals to amplitude information of such interval; and
discard the phase information associated with the resistive-inductive-capacitive sensor during such interval responsive to a difference between the driving amplitude of the interval and the amplitude information of such interval exceeding a threshold difference.
14. The system of claim 1 , wherein the measurement circuit is further configured to:
compare the driving frequency of an interval of the plurality of periodic intervals to phase information of such interval; and
discard the phase information associated with the resistive-inductive-capacitive sensor during such interval responsive to a difference between the driving frequency of the interval and the phase information of such interval exceeding a threshold difference.
15. A method comprising:
at a plurality of periodic intervals, measure phase information associated with a resistive-inductive-capacitive sensor;
based on the phase information, determine a displacement of a mechanical member relative to the resistive-inductive-capacitive sensor; and
driving the resistive-inductive-capacitive sensor at a driving frequency and a driving amplitude, wherein at least one of the driving frequency and the driving amplitude varies among the plurality of periodic intervals.
16. The method of claim 15 , further comprising varying at least one of the driving frequency and the driving amplitude among the plurality of periodic intervals in at least one of a sequential manner, a random manner, a pseudo-random manner, and a deterministic manner.
17. The method of claim 15 , further comprising setting the driving frequency with a voltage-controlled oscillator.
18. The method of claim 17 , further comprising setting the driving frequency using a tuning voltage of the voltage-controlled oscillator.
19. The method of claim 17 , further comprising modulating the voltage-controlled oscillator in accordance with a frequency modulation or a phase modulation in order to set the driving frequency.
20. The method of claim 15 , further comprising selecting a voltage-controlled oscillator from a plurality of voltage-controlled oscillators each having a different oscillation frequency, such that a selection of the voltage-controlled oscillator from the plurality of voltage-controlled oscillators is used to set the driving frequency.
21. The method of claim 15 , further comprising modifying a resonant frequency of the resistive-inductive-capacitive sensor responsive to varying of the driving frequency by modifying a reactance of a passive reactive circuit element external to the resistive-inductive-capacitive sensor.
22. The method of claim 15 , further comprising blanking at least one of a clock or data associated with a measurement circuit for measuring the phase information while the driving frequency is in transition between two frequencies.
23. The method of claim 15 , further comprising determining an occurrence of a physical interaction associated with a human-machine interface associated with the mechanical member based on the phase information.
24. The method of claim 23 , further comprising processing the phase information and data from at least one other sensor to determine the occurrence of the physical interaction.
25. The method of claim 24 , wherein the at least one other sensor comprises one or more of an accelerometer, a gyroscope, a touch sensor, a proximity sensor, a temperature sensor, and an ambient light sensor.
26. The method of claim 15 , further comprising tracking a resonant frequency of the resistive-inductive-capacitive sensor wherein the phase information is measured using a coherent incident/quadrature detector.
27. The method of claim 15 , further comprising:
at the plurality of periodic intervals, measuring amplitude information associated with the resistive-inductive-capacitive sensor;
comparing the driving amplitude of an interval of the plurality of periodic intervals to amplitude information of such interval; and
discarding the phase information associated with the resistive-inductive-capacitive sensor during such interval responsive to a difference between the driving amplitude of the interval and the amplitude information of such interval exceeding a threshold difference.
28. The method of claim 15 , further comprising:
comparing the driving frequency of an interval of the plurality of periodic intervals to phase information of such interval; and
discarding the phase information associated with the resistive-inductive-capacitive sensor during such interval responsive to a difference between the driving frequency of the interval and the phase information of such interval exceeding a threshold difference.