Vibrators, vibratory gyroscopes, devices for measuring a linear acceleration and a method of measuring a turning angular rate

• US 20010001928A1
• Filed: 01/02/2001
• Published: 05/31/2001
• Est. Priority Date: 11/04/1997
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: NGK Insulators Limited
• Inventors: Kikuchi, Takayuki, Osugi, Yukihisa, Gouji, Shosaku, Soma, Takao
• Granted Patent: US 6,439,051 B2
• Time in Patent Office: Days
• US Class Current: 73/504.12
• CPC Class Codes: G01C 19/5607 using vibrating tuning forks double-ended tuning forks using planar vibrating masses suspended at opposite ends G01C19/5719
• CPC Class Codes: G01C 19/5642 using vibrating bars or beams

Abstract

A vibratory gyroscope for detecting a turning angular rate in a turning system is provided. The gyroscope comprises a vibrator, an exciting means for exciting driving vibration in the vibrator, and a detecting means for detecting vibration induced in the vibrator. The vibrator comprises a plurality of vibration systems 1A, 1B, 2A and 2B, which are formed within a specified plane intersecting the turning axis Z. Vibration systems comprises first vibration systems 1A and 1B whose vibrations include radial vibration components, in which the center of gravity of first vibration system vibrates in a radial direction in the specified plane with respect to the center of gravity GO of the vibrator. The vibration systems also comprises second vibration systems 2A and 2B whose vibrations include circumferential vibration components, in which the center of gravity of vibration of the second vibration system vibrates in the specified plane along a circle with the center of gravity GO as its center.

Claims

1. A vibrator to be turned around a turning axis and having a center of gravity (GO), comprising:

a first vibration system whose vibration includes a radial vibration component with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator;

a second vibration system whose vibration includes a circumferential vibration component with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator; and

a base portion;

wherein said first vibration system, said second vibration system and said base portion are formed along a specified plane intersecting said turning axis, and wherein said first vibration system and said second vibration system are connected through said base portion.

2. The vibrator of

claim 1

, wherein said first and second vibration systems are connected only through said base portion without any other connection.

3. The vibrator of

claim 1

, wherein a ratio between amplitudes of said radial vibration component and a circumferential vibration component, with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator, in said first vibration system is 1:

0 to 3.

4. The vibrator of

claim 3

, wherein said ratio is 1:

0 to 1.

5. The vibrator of

claim 1

, wherein a ratio between amplitudes of a radial vibration component, with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator, and said circumferential vibration component in said second vibration system is 0 to 1:

5.

6. The vibrator of

claim 5

, wherein said ratio is 0 to 1:

10.

7. The vibrator of

claim 1

, wherein said vibrator has a plurality of said first vibration systems, and a ratio between amplitudes of said radial vibration component and a circumferential vibration component, with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator, in said first vibration systems is 5:

0 to 1, provided that said first vibration systems vibrate in vibration modes containing vibration components having inverse phases with each other and said amplitudes are measured after canceling said vibration components having inverse phases.

8. The vibrator of

claim 7

, wherein said ratio is 10:

0 to 1.

9. The vibrator of

claim 1

, wherein said first vibration system and said second vibration system vibrate in substantially independent vibration modes.

10. The vibrator of

claim 1

, wherein said base portion does not substantially vibrate in bending vibration mode.

11. The vibrator of

claim 1

, wherein said base portion does not constitute a part of a bending vibration piece.

12. The vibrator of

claim 1

, wherein said center of gravity of said vibrator is located in or near said base portion.

13. The vibrator of

claim 1

, wherein said base portion has a peripheral part, and wherein said first vibration system and said second vibration system extend from said peripheral part.

14. The vibrator of

claim 13

, wherein adjacent vibration systems extend from said peripheral part in directions intersecting at an angle not smaller than 30°

with respect to said center of gravity of said vibrator.

15. The vibrator of

claim 1

, wherein a plurality of said first vibration systems are provided in positions which are substantially identical after turning said positions around said center of gravity of said vibrator.

16. The vibrator of

claim 15

, wherein said first vibration systems are provided in positions which are diad-symmetrical, triad-symmetrical or tetrad-symmetrical with each other with respect to said center of gravity of said vibrator.

17. The vibrator of

claim 1

, wherein a plurality of said second vibration systems are provided in positions which are substantially identical after turning said positions around said center of gravity of said vibrator.

18. The vibrator of

claim 17

, wherein said second vibration systems are provided in positions which are diad-symmetrical, triad-symmetrical or tetrad-symmetrical with each other with respect to said center of gravity of said vibrator.

19. The vibrator of

claim 1

, wherein each of said first vibration systems and said second vibration systems has a bending vibration piece connected with said base portion, and wherein said bending vibration piece vibrates in bending motion around the root of said piece to said base portion.

20. The vibrator of

claim 1

, wherein said base portion is a frame having an inner peripheral part and an outer peripheral part.

21. The vibrator of

claim 20

, wherein at least one of said first vibration system and second vibration system extend from said inner peripheral part.

22. The vibrator of

claim 1

, wherein said first vibration system comprises first bending-vibration piece or pieces whose vibration includes at least said radial vibration component and a supporting portion extending from said base portion, and wherein said first bending-vibration piece extends in a direction intersecting the longitudinal direction of said supporting portion.

23. The vibrator of

claim 1

, wherein said second vibration system comprises a bending-vibration piece whose vibration includes at least said circumferential vibration component and said bending-vibration piece is connected with said base portion.

24. A vibratory gyroscope for detecting a turning angular rate around a turning axis comprising:

a vibrator to be turned around said turning axis and having a center of gravity (GO), said vibrator comprising;

a first vibration system whose vibration includes a radial vibration component with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator, a second vibration system whose vibration includes a circumferential vibration component with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator, and a base portion, wherein said first vibration system, said second vibration system and said base portion are formed along a specified plane intersecting said turning axis, and wherein said first vibration system and said second vibration system are connected through said base portion;

exciting means provided in one of said first vibration system and said second vibration system for exciting a driving vibration in said vibrator; and

detecting means provided in the other of said first vibration system and second vibration system for detecting a detecting vibration that occurs due to Coriolis force in said vibrator when said vibrator is turned around said turning axis.

25. The vibratory gyroscope of

claim 24

, wherein said first and second vibration systems are connected only through said base portion without any other connection.

26. The vibratory gyroscope of

claim 24

, wherein a ratio between amplitudes of said radial vibration component and a circumferential vibration component, with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator, in said first vibration system is 1:

0 to 3.

27. The vibratory gyroscope of

claim 26

, wherein said ratio is 1:

0 to 1.

28. The vibratory gyroscope of

claim 24

, wherein a ratio between amplitudes of a radial vibration component, with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator, and said circumferential vibration component in said second vibration system is 0 to 1:

5.

29. The vibratory gyroscope of

claim 28

, wherein said ratio is 0 to 1:

10.

30. The vibratory gyroscope of

claim 24

, wherein said vibrator has a plurality of said first vibration systems, and a ratio between amplitudes of said radial vibration component and a circumferential vibration component, with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator, in said first vibration systems is 5:

0 to 1, provided that said first vibration systems vibrate in vibration modes containing vibration components having inverse phases with each other and said amplitudes are measured after canceling said vibration components having inverse phases.

31. The vibratory gyroscope of

claim 30

, wherein said ratio is 10:

0 to 1.

32. The vibratory gyroscope of

claim 24

, wherein said first vibration system and said second vibration system vibrate in substantially independent vibration modes.

33. The vibratory gyroscope of

claim 24

, wherein said base portion does not substantially vibrate in bending vibration mode.

34. The vibratory gyroscope of

claim 24

, wherein said base portion does not constitute a part of a bending vibration piece.

35. The vibratory gyroscope of

claim 24

, wherein said center of gravity of said vibrator is located in or near said base portion.

36. The vibratory gyroscope of

claim 24

, wherein said base portion has a peripheral part, and wherein said first vibration system and said second vibration system extend from said peripheral part.

37. The vibratory gyroscope of

claim 36

, wherein adjacent vibration systems extend from said peripheral part in directions intersecting at an angle not smaller than 30°

with respect to said center of gravity of said vibrator.

38. The vibratory gyroscope of

claim 24

, wherein a plurality of said first vibration systems are provided in positions which are substantially identical after turning said positions around said center of gravity of said vibrator.

39. The vibratory gyroscope of

claim 38

, wherein said first vibration systems are provided in positions which are diad-symmetrical, triad-symmetrical or tetrad-symmetrical with each other with respect to said center of gravity of said vibrator.

40. The vibratory gyroscope of

claim 24

, wherein a plurality of said second vibration systems are provided in positions which are substantially identical after turning said positions around said center of gravity of said vibrator.

41. The vibratory gyroscope of

claim 40

, wherein said first vibration systems are provided in positions which are diad-symmetrical, triad-symmetrical or tetrad-symmetrical with each other with respect to said center of gravity of said vibrator.

42. The vibratory gyroscope of

claim 24

, wherein each of said first vibration systems and said second vibration systems has a bending vibration piece connected with said base portion, and wherein said bending vibration piece vibrates in bending motion around the root of said piece to said base portion.

43. The vibratory gyroscope of

claim 24

, wherein said base portion is a frame having an inner peripheral part and an outer peripheral part.

44. The vibratory gyroscope of

claim 43

, wherein at least one of said first vibration system and second vibration system extend from said inner peripheral part.

45. The vibratory gyroscope of

claim 24

, wherein said first vibration system comprises first bending-vibration piece or pieces whose vibration includes at least said radial vibration component and a supporting portion extending from said base portion, and wherein said first bending-vibration piece extends in a direction intersecting the longitudinal direction of said supporting portion.

46. The vibratory gyroscope of

claim 24

, wherein said second vibration system comprises a bending-vibration piece whose vibration includes at least said circumferential vibration component and said bending-vibration piece is connected with said base portion.