Resonator

Patent metadata

Field	Value
Publication number	US-8988017-B2
Application number	US-201313927404-A
Country	US
Kind code	B2
Filing date	Jun 26, 2013
Priority date	Jun 29, 2012
Publication date	Mar 24, 2015
Grant date	Mar 24, 2015

Abstract

A mechanical resonator with a closed feed-back damping loop is provided. Displacement in the mechanical resonator is opposed with a damping force determined by the closed feed-back loop that comprises a signal processing filter with associated phase adjustment. An oscillation-free configuration that allows high signal amplification is achieved.

First claim

The invention claimed is:

1. A control element, comprising:
an input for a first electrical signal that corresponds to a displacement of reference point in a mechanical resonator in response to forces acting upon the mass;
an output for a second electrical signal that defines a damping feed-back force to be acted upon the mechanical resonator; and
a signal processing filter for generating a second electrical signal according to a specific response function, the response function defining correspondence between values of the first electrical signal and the second electrical signal.

2. A control element according to claim 1 , wherein the first electrical signal has a first resonant frequency, and the response function is a frequency response function that has a resonant frequency characteristic that essentially coincides with the first resonant frequency.

3. A control element according to claim 2 , wherein the quality factor of the signal processing filter is above 1.

4. A control element according to claim 3 , wherein the quality factor of the signal processing filter is in the range 3 to 10.

5. A resonator device comprising:
a mechanical resonator;
a closed feed-back loop including a first transducer, a second transducer and a control element;
the first transducer is configured to output a first electrical signal that corresponds to displacement of a reference point in the mechanical resonator with respect to an inertial frame of reference, the first electrical signal having a first resonant frequency;
the control element is electrically coupled to the first transducer and the second transducer;
the control element is configured to receive from the first transducer the first electrical signal and generate a second electrical signal according to a specific response function, the response function defining correspondence between values of the first electrical signal and the second electrical signal;
the control element is configured to feed the second electrical signal to the second transducer;
the second transducer is configured to exert to the mechanical resonator a damping force that corresponds to the second electrical signal; and
the control element is a signal processing filter.

6. A resonator device according to claim 5 , wherein the response function of the signal processing filter has a resonant frequency characteristic that essentially coincides with the first resonant frequency.

7. A resonator device according to claim 6 , wherein the quality factor of the signal processing filter is more than 1.

8. A resonator device according to claim 7 , wherein the quality factor of the signal processing filter is in the range 3 to 10.

9. A resonator device according to claim 5 , wherein the loop gain of the closed feed-back loop for frequencies below the first resonant frequency is less than 1.

10. A resonator device according to claim 9 , wherein the loop gain of the closed feed-back loop for frequencies below the first resonant frequency is in the range 0.1 to 0.3.

11. A resonator device according to claim 5 , wherein deviation of the resonant frequency characteristic from the first resonant frequency is less than 50%.

12. A resonator device according to claim 11 , wherein deviation of the resonant frequency characteristic from the first resonant frequency is less than 20%.

13. A resonator device according to claim 5 , wherein the control element is a low-pass filter and the feed-back of the closed feed-back loop is positive.

14. A resonator device according to claim 5 , wherein the control element is a high-pass filter and the feed-back of the closed feed-back loop is negative.

15. A resonator device according to claim 5 , wherein the control element is a combination of a band-pass filter and an all-pass filter and the feed-back of the closed feed-back loop is positive.

16. A resonator device according to claim 5 , wherein the control element is an all-pass filter and the feed-back of the closed feed-back loop is positive.

17. A resonator device according to claim 5 , wherein the sensing device is a MEMS device.

18. A method according to claim 17 , wherein the response function of the signal processing filter has a resonant frequency characteristic that essentially coincides with the first resonant frequency.

19. A resonator device according to claim 5 , wherein the first transducer is configured to detect displacement by means of motion, stress or strain based on capacitive effect, piezoelectric effect, electromagnetic effect or piezoresistive effect.

20. A resonator device according to claim 5 , wherein the second transducer is configured to induce displacement by means of force, torque, stress or strain based on electrostatic effect, piezoelectric effect, electromagnetic effect, thermelastic effect, electrostriction or magnetostriction.

21. A resonator device according to claim 5 , wherein the resonator device is a sensor device or an actuator device.

22. A method for controlling operation of a mechanical resonator, comprising:
coupling the mechanical resonator to a closed feed-back loop including a first transducer, a second transducer and a control element;
outputting from the first transducer to the control element a first electrical signal that corresponds to displacement of a reference point in the mechanical resonator with respect to an inertial frame of reference, the first electrical signal having a first resonant frequency;
generating in the control element a second electrical signal according to a specific response function, the response function defining correspondence between values of the first electrical signal and the second electrical signal, the control element being a signal processing filter;
feeding the second electrical signal from the control element to the second transducer; and
exerting with the second transducer to the mechanical resonator a damping force that corresponds to the second electrical signal and opposes the displacement.

Assignees

• Murata Electronics Oy
• Murata Manufacturing Co

Inventors

• Kuisma Heikki

Classifications

• H03B5/30

  with frequency-determining element being electromechanical resonator · CPC title

• G01C19/5776

  Signal processing not specific to any of the devices covered by groups G01C19/5607 - G01C19/5719 · CPC title

• B81B7/008 Primary

  MEMS characterised by an electronic circuit specially adapted for controlling or driving the same (B81B7/0087 takes precedence; arrangements for starting, regulating, braking, or otherwise controlling an actuator H02N; control arrangements or circuits for visual indicators G09G3/00) · CPC title

• G01P15/13

  by measuring the force required to restore a proofmass subjected to inertial forces to a null position · CPC title

• H02N11/006 Primary

  Motors · CPC title