False triggering prevention in a resonant phase sensing system

• US 10,642,435 B2
• Filed: 03/06/2019
• Issued: 05/05/2020
• Est. Priority Date: 03/29/2018
• Status: Active Grant

• Current Assignee: Cirrus Logic Incorporated
• Original Assignee: Cirrus Logic Incorporated
• Inventors: Maru, Siddharth, Das, Tejasvi, Lapointe, Luke, Marijanovic, Srdjan, You, Zhong, Kinney, Drew, Doy, Anthony S., King, Eric J.
• Primary Examiner(s): Park, Sanghyuk
• Application Number:
  US16/294,311
• Publication Number:
  US 20190302923A1
• Time in Patent Office: 426 Days
• CPC Class Codes: G01D 5/2006 by influencing the self-induction of one or more coils G01D5/22 takes precedence
• CPC Class Codes: G01D 5/2026 constituting a short-circuiting element
• CPC Class Codes: G01D 5/243 influencing the phase or frequency of ac
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

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.

Claims

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.