Vibrator drive circuit

• US 10,175,045 B2
• Filed: 09/13/2016
• Issued: 01/08/2019
• Est. Priority Date: 03/25/2014
• Status: Active Grant

• Current Assignee: Murata Manufacturing Co Limited
• Original Assignee: Murata Manufacturing Co Limited
• Inventors: Ono, Hidekazu, Tsuji, Nobuaki, Okami, Tsuyoshi, Mizota, Takashi
• Primary Examiner(s): Walsh, Ryan D
• Application Number:
  US15/263,545
• Publication Number:
  US 20160377435A1
• Time in Patent Office: 847 Days
• CPC Class Codes: G01C 19/5726 Signal processing

Abstract

A vibrator drive circuit is configured to drive a vibrator mass 3 in a prescribed vibration direction. The vibrator drive circuit includes a drive unit configured to drive a vibrator based on a reference signal SG1 of a predetermined frequency to cause the vibrator to vibrate in a vibration direction, a phase detector configured to detect a vibration waveform of the vibrator in the vibration direction and to output an output voltage Vcnt in accordance with a phase difference between reference signal SG1 and a vibration waveform thereof, and two capacitors each formed of a movable electrode provided in the vibrator and a fixed electrode provided to face the movable electrode, the output voltage Vcnt being applied to the fixed electrode. The phase detector is configured to adjust the output voltage Vcnt in accordance with the phase difference, thereby changing electrostatic force in each of the capacitors for controlling the phase difference to be 90 degrees.

Claims

1. A combination, comprising:

a vibrator comprising a vibrator mass which is free to vibrate in first and second orthogonal directions;

a signal generator for generating a drive signal which is applied to the vibrator and causes the vibrator mass to vibrate in the first direction;

at least one phase adjusting capacitor coupled to the vibrator mass and serving to adjust the phase of the vibration of the vibrator mass in the first direction as a function of a phase correction signal applied thereto, each of the at least one phase adjusting capacitors including a stationary plate and a moveable plate, the moveable plate being coupled to the vibrator mass for movement therewith; and

a phase detector which detects the phase at which the vibrator mass vibrates in the first direction relative to the phase of the drive signal and generates the phase correction signal as a function of the detected phase.

2. The combination of claim 1, wherein the phase correction signal causes the vibration of the vibrator mass to be 90 degrees out of phase with the drive signal.

3. The combination of claim 1, wherein the vibrator includes a drive capacitor which receives the drive signal.

4. The combination of claim 3, wherein the drive capacitor includes a stationary plate and a moveable plate, the moveable plate being coupled to the vibrator mass for movement therewith.

5. The combination of claim 1, wherein the phase detector receives a signal indicative of the vibration of the vibrator mass from at least one phase detection capacitor coupled to the vibrator mass.

6. The combination of claim 5, wherein each of the at least one phase detection capacitors includes a stationary plate and a moveable plate, the moveable plate being coupled to the vibrator mass for movement therewith.

7. The combination of claim 1, further comprising an angular velocity detector for generating an angular velocity signal as a function of movement of the vibrator mass in the second direction.

8. The combination of claim 1, wherein the vibrator includes a spring structure which allows the vibrator mass to move in the first and second directions.

9. The combination of claim 1, wherein the drive signal has a frequency that is different than a resonance frequency of the vibrator mass.

10. A combination comprising:

a first vibrator including a first vibrator mass, the first vibrator mass being arranged to vibrate in first and second orthogonal directions;

a second vibrator including a second vibrator mass, the second vibrator mass being arranged to vibrate in third and fourth orthogonal directions, the third direction being different than the first direction;

a signal generator for generating a drive signal which is applied the first and second vibrators and causes the first and second vibrator masses to vibrate in the first and third directions, respectively;

at least one first phase adjusting capacitor coupled to the first vibrator mass and serving to adjust the phase of the vibration mass of the first vibrator in the first direction as a function of a first phase correction signal, each of the at least one first phase adjusting capacitors including a stationary plate and a moveable plate, the moveable plate of each respective first phase adjusting capacitor being coupled to the first vibrator mass for movement therewith;

a first phase detector which detects the phase at which the first vibrator mass vibrates in the first direction relative to the phase of the drive signal and generates the first phase correction signal as a function of the so detected phase;

at least one second phase adjusting capacitor coupled to the second vibrator mass and serving to adjust the phase of the vibration of the second vibrator mass in the third direction as a function of a second phase correction signal applied thereto, each of the at least one second phase adjusting capacitors including a stationary plate and a moveable plate, the moveable plate of each respective second phase adjusting capacitor being coupled to the second vibrator mass for movement therewith; and

a second phase detector which detects the phase at which the second vibrator mass vibrates in the third direction relative to the phase of the drive signal and generates the second phase correction signal as a function of the detected phase.

11. The combination of claim 10, wherein:

the first phase correction signal causes the vibration of the first vibrator mass to be 90 degrees out of phase with the drive signal; and

the second phase correction signal causes the vibration of the second vibrator mass to be 90 degrees out of phase with the drive signal.

12. The combination of claim 10, wherein:

the first vibrator includes a first drive capacitor which receives drive signal; and

the second vibrator includes a second drive capacitor which receives the drive signal.

13. The combination of claim 12, wherein:

the first drive capacitor includes a stationary plate and a moveable plate, the moveable plate of the first drive capacitor being coupled to the first vibrator mass for movement therewith; and

the second drive capacitor includes a stationary plate and a moveable plate, the moveable plate of the second drive capacitor being coupled to the second vibrator mass for movement therewith.

14. The combination of claim 10, wherein:

the first phase detector receives first signal from a phase detection capacitor coupled to the first vibrator mass; and

the second phase detector receives second signal from a phase detection capacitor coupled to the second vibrator mass.

15. The combination of claim 14, wherein:

the first phase detection capacitor includes a stationary plate and a moveable plate, the moveable plate of the first phase detection capacitor being coupled to the first vibrator mass for movement therewith; and

the second phase detection capacitor includes a stationary plate and a moveable plate, the moveable plate of the second phase detection capacitor being coupled to the second vibrator mass for movement therewith.

16. The combination of claim 10, further comprising:

a first angular velocity detector for generating a first angular velocity signal as a function of movement of the first vibrator mass in the second direction; and

a second angular velocity detector for generating a second angular velocity signal as a function of movement of the second vibrator mass in the fourth direction.

17. The combination of claim 10, wherein:

the first vibrator includes a first spring structure which allows the first vibrator mass to move in the first and second directions; and

the second vibrator includes a second spring structure which allows the second vibrator mass to move in the third and fourth directions.

18. The combination of claim 10, wherein the drive signal has a frequency that is different than a resonance frequency of at least one of the first and second vibrator masses.