Vibrator, vibratory gyroscope, and vibrator adjusting method

• US 6,346,765 B1
• Filed: 10/19/1999
• Issued: 02/12/2002
• Est. Priority Date: 11/26/1996
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: NGK Insulators Limited
• Inventors: Soma, Takao, Kikuchi, Takayuki, Osugi, Yukihisa, Gouji, Shosaku
• Primary Examiner(s): BUDD, MARK OSBORNE
• Application Number:
  US09/420,350
• Time in Patent Office: 847 Days
• Field of Search: 310/321, 310/329, 310/367, 310/316.01
• US Class Current: 310/367
• CPC Class Codes: G01C 19/5607 using vibrating tuning forks double-ended tuning forks using planar vibrating masses suspended at opposite ends G01C19/5719

Abstract

A vibrator of a vibratory gyroscope comprises a main arm having a base part and at least one bending-vibration piece extending from the base part in a direction crossing the longitudinal direction of the base part and a fixing part for fixing one end of the base part, and the base part and the bending-vibration piece are formed so as to extend substantially in a specified plane. Preferably, at the opposite side to one end of the base part, a projection projecting from the bending-vibration piece is provided, or at least a pair of resonant arms resonating with vibration of the base part, said pair of resonant arms projecting from the fixing part are provided. Thanks to this, it has been possible to detect a turning angular rate in a sufficiently high accuracy without providing a projection which has a certain weight and extends from the vibrator toward the axis of turning even in case of arranging the vibrator so that the vibration arm of the vibrator extends perpendicularly to the axis of turning.

Claims

1. A vibratory gyroscope for detecting a turning angular rate about an axis of rotation, said vibratory gyroscope comprising:

a vibrator comprising (i) a fixing part arranged in a plane substantially perpendicular to said axis of rotation, (ii) a substantially straight base part arranged in said plane and having a first end attached to said fixing part and a second end opposed thereto in the longitudinal direction of said base part, (iii) at least one bending vibration piece arranged in said plane and having a first end attached to a portion of said base part other than said first end of said base part, and a second end distal from said first end in a longitudinal direction of said bending vibration piece, the longitudinal direction of said bending vibration piece intersecting the longitudinal direction of said base part, and (iv) at least one pair of resonant arms arranged within said plane and extending from said fixing part, wherein said base part and said bending vibration piece both vibrate in a bending vibration mode substantially within said plane using said first ends thereof, respectively, as their fulcrum, and wherein said resonant arms resonate with vibration of said base part;

excitation means for exciting vibration of one of said base part and said bending vibration piece in said plane; and

detection means for detecting bending vibration of said vibrator generated by Coriolis force within said vibrator as a result of said vibrator being rotated around said axis of rotation;

wherein one of said excitation means and said detection means is positioned on said bending vibration piece.

2. The vibratory gyroscope of claim 1, wherein said first end of said bending vibration piece is attached to said base part at said second end thereof.

3. The vibratory gyroscope of claim 2, wherein said bending vibration piece comprises a pair of pieces, the first end of each piece being attached to said base part at said second end thereof so that said bending vibration pieces are symmetrical about a longitudinal axis of said base part.

4. The vibratory gyroscope of claim 2, further comprising a projection piece arranged within said plane and extending from said second end of said base part in a direction substantially parallel with a longitudinal axis of said base part.

5. The vibratory gyroscope of claim 3, further comprising a projection piece arranged within said plane and extending from said second end of said base part in a direction substantially parallel with a longitudinal axis of said base part.

6. The vibratory gyroscope of claim 1, wherein said resonant arms extend substantially parallel to said base part.

7. The vibratory gyroscope of claim 6, wherein portions of said fixing part positioned between said base part and said resonant arms extend along said base part and said resonant arms a predetermined distance beyond a remaining portion of said fixing part.

8. The vibratory gyroscope of claim 1, wherein said bending vibration piece has a through hole passing therethrough in a direction substantially perpendicular to said plane.

9. The vibratory gyroscope of claim 1, wherein each of said resonant arms has a through hole passing therethrough in a direction substantially perpendicular to said plane.

10. The vibratory gyroscope of claim 1, wherein said base part extends in a first direction away from said fixing part, and said vibrator further comprises an additional resonant arm arranged in said plane and extending in a second direction, diametrically opposed to said first direction, away from said fixing part.

11. The vibratory gyroscope of claim 2, wherein said base part extends in a first direction away from said fixing part, and said vibrator further comprises an additional resonant arm arranged in said plane and extending in a second direction, diametrically opposed to said first direction, away from said fixing part.

12. The vibratory gyroscope of claim 3, wherein said base part extends in a first direction away from said fixing part, and said vibrator further comprises an additional resonant arm arranged in said plane and extending in a second direction, diametrically opposed to said first direction, away from said fixing part.

13. The vibratory gyroscope of claim 10, wherein said pair of resonant arms extend in said first direction.

14. The vibratory gyroscope of claim 11, wherein said pair of resonant arms extend in said first direction.

15. The vibratory gyroscope of claim 12, wherein said pair of resonant arms extend in said first direction.

16. The vibratory gyroscope of claim 1, wherein the longitudinal direction of said bending vibration piece intersects the longitudinal direction of said base part at an angle of 45°

to 135°

.

17. The vibratory gyroscope of claim 1, wherein the longitudinal direction of said bending vibration piece intersects the longitudinal direction of said base part at an angle of about 90°

.

18. The vibratory gyroscope of claim 1, wherein said excitation means comprises at least one driving electrode positioned on said base part.

19. The vibratory gyroscope of claim 18, wherein said detecting means comprises detecting electrodes positioned on said bending vibration piece.

20. The vibratory gyroscope of claim 1, wherein said excitation means comprises at least one driving electrode positioned on said bending vibration piece.

21. The vibratory gyroscope of claim 20, wherein said detecting means comprises detecting electrodes positioned on said base part.

22. The vibratory gyroscope of claim 10, wherein said excitation means comprises at least one driving electrode positioned on said resonant arm.

23. The vibratory gyroscope of claim 22, wherein said detecting means comprises detecting electrodes positioned on said bending vibration piece.

24. The vibratory gyroscope of claim 10, wherein said excitation means comprises at least one driving electrode positioned on said bending vibration piece.

25. The vibratory gyroscope of claim 24, wherein said detecting means comprises detecting electrodes positioned on said resonant arm.

26. The vibratory gyroscope of claim 1, wherein said excitation means comprises driving electrodes positioned on said pair of resonant arms.

27. The vibratory gyroscope of claim 26, wherein said detecting means comprises detecting electrodes positioned on said bending vibration piece.

28. The vibratory gyroscope of claim 20, wherein said detecting means comprises detecting electrodes positioned on said pair of resonant arms.

29. The vibratory gyroscope of claim 1, wherein said base part, said bending vibration piece, and said pair of resonant arms are formed from a piezoelectric single crystal selected from the group consisting of quartz, LiTaO₃, LiNbO₃, and Li(Nb,Ta)O₃.

30. The vibratory gyroscope of claim 1, wherein said pair of resonant arms extend in directions that intersect, within said fixing part, a longitudinal extension of said base part.

54. The vibratory gyroscope of claim 1, wherein said vibrator comprises at least one pair of said base parts and wherein a space is formed and surrounded by said fixing part, said base parts and said bending vibration piece.

55. The vibratory gyroscope of claim 54, wherein said vibrator comprises at least two pairs of said base parts and at lease two bending vibration pieces and wherein at least two spaces are formed within said vibrator, one space being formed and surrounded by said fixing part, one of said two pairs of base parts and one of said bending vibration pieces and the other space being formed and surrounded by said fixing part, the other of said two pairs of base parts and the other of said bending vibration pieces.

56. The vibratory gyroscope of claim 1, wherein said resonant arms extend from said fixing part in opposite directions.

57. The vibratory gyroscope of claim 54, wherein said resonant arms extend from said fixing part in opposite directions.

58. The vibratory gyroscope of claim 1, wherein said resonant arms are substantially straight and said bending vibration piece is substantially straight, said resonant arms being substantially parallel with said bending vibration piece.

31. A vibrator comprising:

a fixing part arranged in a plane;

a substantially straight base part arranged in said plane and having a first end attached to said fixing part and a second end opposed thereto in the longitudinal direction of said base part;

at least one bending vibration piece arranged in said plane and having a first end attached to a portion of said base part other than said first end of said base part, and a second end distal from said first end in a longitudinal direction of said bending vibration piece, the longitudinal direction of said bending vibration piece intersecting the longitudinal direction of said base part;

at least one pair of resonant arms arranged within said plane and extending from said fixing part, wherein said base part and said bending vibration piece both vibrate in a bending vibration mode substantially within said plane using said first ends thereof, respectively, as their fulcrum, and wherein said resonant arms resonate with vibration of said base part; and

excitation means for exciting vibration of one of said base part and said bending vibration piece in said plane.

32. The vibrator of claim 31, wherein said first end of said bending vibration piece is attached to said base part at said second end thereof.

33. The vibrator of claim 32, wherein said bending vibration piece comprises a pair of pieces, the first end of each piece being attached to said base part at said second end thereof so that said bending vibration pieces are symmetrical about a longitudinal axis of said base part.

34. The vibrator of claim 32, further comprising a projection piece arranged within said plane and extending from said second end of said base part in a direction substantially parallel with a longitudinal axis of said base part.

35. The vibrator of claim 33, further comprising a projection piece arranged within said plane and extending from said second end of said base part in a direction substantially parallel with a longitudinal axis of said base part.

36. The vibrator of claim 31, wherein said resonant arms extend substantially parallel to said base part.

37. The vibrator of claim 36, wherein portions of said fixing part positioned between said base part and said resonant arms extend along said base part and said resonant arms a predetermined distance beyond a remaining portion of said fixing part.

38. The vibrator of claim 31, wherein said bending vibration piece has a through hole passing therethrough in a direction substantially perpendicular to said plane.

39. The vibrator of claim 31, wherein each of said resonant arms has a through hole passing therethrough in a direction substantially perpendicular to said plane.

40. The vibrator of claim 31, wherein said base part extends in a first direction away from said fixing part, and said vibrator further comprises an additional resonant arm arranged in said plane and extending in a second direction, diametrically opposed to said first direction, away from said fixing part.

41. The vibrator of claim 32, wherein said base part extends in a first direction away from said fixing part, and said vibrator further comprises an additional resonant arm arranged in said plane and extending in a second direction, diametrically opposed to said first direction, away from said fixing part.

42. The vibrator of claim 33, wherein said base part extends in a first direction away from said fixing part, and said vibrator further comprises an additional resonant arm arranged in said plane and extending in a second direction, diametrically opposed to said first direction, away from said fixing part.

43. The vibrator of claim 40, wherein said pair of resonant arms extend in said first direction.

44. The vibrator of claim 41, wherein said pair of resonant arms extend in said first direction.

45. The vibrator of claim 42, wherein said pair of resonant arms extend in said first direction.

46. The vibrator of claim 31, wherein the longitudinal direction of said bending vibration piece intersects the longitudinal direction of said base part at an angle of about 90°

.

47. The vibrator of claim 31, wherein said excitation means comprises at least one driving electrode positioned on said base part.

48. The vibrator of claim 31, wherein said excitation means comprises at least one driving electrode positioned on said bending vibration piece.

49. The vibrator of claim 40, wherein said excitation means comprises at least one driving electrode positioned on said resonant arm.

50. The vibrator of claim 31, wherein said excitation means comprises driving electrodes positioned on said pair of resonant arms.

51. The vibrator of claim 31, wherein said base part comprises first and second base parts, each having a first end attached to said fixing part and a free second end distal from said first end in a longitudinal direction of said base part, and wherein said first end of said bending vibration piece is attached to said second end of said first base part and said second end of said bending vibration piece is attached to said second end of said second base part.

52. The vibrator of claim 31, wherein said base part, said bending vibration piece, and said pair of resonant arms are formed from a piezoelectric single crystal selected from the group consisting of quartz, LiTaO₃, LiNbO₃, and Li(Nb,Ta)O₃.

53. The vibrator of claim 31, wherein said pair of resonant arms extend in directions that intersect, within said fixing part, a longitudinal extension of said base part.

59. The vibrator of claim 31, wherein said vibrator comprises at least one pair of said base parts, wherein a space is formed and surrounded by said fixing part, said base parts and said bending vibration piece.

60. The vibrator of claim 59, wherein said vibrator comprises at least two pairs of said base parts and at least two bending vibration pieces, wherein at least two spaces are formed within said vibrator, one space being formed and surrounded by said fixing part, one of said two pairs of base parts and one of said bending vibration pieces, and the other space being formed and surrounded by said fixing part, the other of said two pairs of base parts and the other of said bending vibration pieces.

61. The vibrator of claim 31, wherein said resonant arms extend from said fixing part in opposite directions.

62. The vibrator of claim 59, wherein said resonant arms extend from said fixing part in opposite directions.

63. The vibrator of claim 31, wherein said resonant arms are substantially straight and said bending vibration piece is substantially straight, said resonant arms being substantially parallel with said bending vibration piece.