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

• US 6,227,048 B1
• Filed: 10/29/1998
• Issued: 05/08/2001
• Est. Priority Date: 11/04/1997
• Status: Expired due to Term

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: NGK Insulators Limited
• Inventors: Kikuchi, Takayuki, Osugi, Yukihisa, Gouji, Shosaku, Soma, Takao
• Primary Examiner(s): CHAPMAN JR, JOHN E
• Application Number:
  US09/181,554
• Time in Patent Office: 922 Days
• Field of Search: 73/504.12, 73/504.13, 73/504.14, 73/504.15, 73/504.16, 73/504.04, 310/321, 310/367
• 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 (Z) and having a center of gravity (GO), said vibrator comprising a plurality of vibration systems (1A, 1B, 2A, 2B) which are formed within a specified plane intersecting said turning axis, said plurality of vibration systems comprising;

a plurality of first vibration systems (1A, 1B) each whose vibration includes a radial vibration component (5A, 5B) with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator, said first vibration systems being symmetrical about said center of gravity of said vibrator;

a second vibration system (2A, 2B) whose vibration includes a circumferential vibration component (6A, 6B) with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator;

means for driving said first vibration systems; and

means for detecting vibration in said second vibration system.

2. The vibrator as claimed in claim 1, wherein said turning axis intersects said specified plane at a right angle.

3. The vibrator as claimed in claim 1, further comprising a base portion (11A) having a peripheral part (11a), and said first and second vibration systems extend from said peripheral part, respectively.

4. The vibrator as claimed in claim 3, wherein said center of gravity of said vibrator is located inside of said peripheral part of said base portion.

5. The vibrator as claimed in claim 4, wherein both of said first and second vibration systems extend from said peripheral part radially with respect to said center of gravity of said vibrator.

6. The vibrator as claimed in claim 5, wherein said plurality of said first vibration systems are provided in positions which are substantially identical with each other after turning said positions around said center of gravity of said vibrator.

7. The vibrator as claimed in claim 6, 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.

8. The vibrator as claimed in claim 6, wherein each first vibration system comprises at least one first bending-vibration piece whose vibration includes at least said radial vibration component.

9. The vibrator as claimed in claim 8, wherein said each first vibration system comprises a supporting portion extending from said base portion and said first bending-vibration piece extends in a direction intersecting the longitudinal direction of said supporting portion.

10. The vibrator as claimed in claim 6, comprising a plurality of second vibration systems located in positions which are substantially identical with each other after turning said positions around said center of gravity of said vibrator.

11. The vibrator as claimed in claim 4, wherein the center of gravity (GD) of said first vibration systems is located on or in the vicinity of said center of gravity of said vibrator.

12. The vibrator as claimed in claim 4, wherein said vibrator comprises two first vibration systems and two second vibration systems, each first vibration system comprising a supporting portion protruding from said peripheral part and at least one first bending-vibration piece intersecting said supporting portion, and each second vibration system comprising one second bending-vibration piece protruding from said peripheral part.

13. The vibrator as claimed in claim 12, wherein said first vibration systems are located in positions which are diad-symmetrical with each other with respect to said center of gravity of said vibrator and said second bending-vibration pieces are located in positions which are diad-symmetrical with each other with respect to said center of gravity of said vibrator.

14. The vibrator as claimed in claim 12, wherein each of said supporting portions bending-vibrates about its connection point to said peripheral part, each of said first bending-vibration pieces bending-vibrates about its connection point to said supporting portion, and each of said second bending-vibration pieces bending-vibrates about its connection point to said peripheral part.

15. The vibrator as claimed in claim 14, wherein each supporting portion and each second bending-vibration piece bending-vibrate in opposite directions to each other in around said center of gravity of said vibrator.

16. The vibrator as claimed in claim 3, wherein each said first vibration system comprises at least one first bending-vibration piece whose vibration includes at least said radial vibration component.

17. The vibrator as claimed in claim 16, wherein each said first vibration system comprises a supporting portion extending from said peripheral part of said base portion and said first bending-vibration piece extends in a direction intersecting the longitudinal direction of said supporting portion.

18. The vibrator as claimed in claim 17, comprising a plurality of said second vibration systems located in positions which are substantially identical with each other after turning said positions around said center of gravity of said vibrator.

19. The vibrator as claimed in claim 17, wherein said second vibration system comprises at least one second bending-vibration piece whose vibration includes at least said circumferential vibration component.

20. The vibrator as claimed in claim 19, wherein said second bending-vibration piece protrudes from said peripheral part of said base portion radially with respect to said center of gravity of said vibrator.

21. The vibrator as claimed in claim 20, wherein each of said supporting portions bending-vibrates about its connection point to said peripheral part, each of said first bending-vibration pieces bending-vibrates about its connection point to said supporting portion, and each of said second bending-vibration pieces bending-vibrates about its connection point to said peripheral part.

22. The vibrator as claimed in claim 21, wherein each supporting portion and each second bending-vibration piece bending-vibrate in opposite directions to each other around said center of gravity of said vibrator.

23. The vibrator as claimed in claim 3, comprising a plurality of second vibration systems located in positions which are substantially identical with each other after turning said positions around said center of gravity of said vibrator.

24. The vibrator as claimed in claim 3, wherein said second vibration system comprises at least one second bending-vibration piece whose vibration includes at least said circumferential vibration component.

25. The vibrator as claimed in claim 24, wherein said second bending-vibration piece protrudes from said peripheral part of said base portion radially with respect to said center of gravity of said vibrator.

26. The vibrator as claimed in claim 1, comprising a thin plate made of a piezoelectric single crystal and electrodes formed on said thin plate.

27. The vibrator as claimed in claim 26, wherein said piezoelectric single crystal is selected from the group consisting of single crystals of quartz, LiNbO₃, LiTaO₃, a solid solution of lithium niobate-lithium tantalate, langasite and lithium tetraborate.

55. The vibrator as claimed in claim 1, wherein said first vibrating systems are symmetrical about a line passing through said center of gravity of said vibrator and said second vibration system is positioned along said line.

28. A vibratory gyroscope for detecting a turning angular rate around a turning axis (Z) comprising:

a vibrator having a center of gravity (GO) and comprising a plurality of vibration systems (1A, 1B, 2A, 2B) which are formed within a specified plane intersecting said turning axis, said plurality of vibration systems comprising a plurality of first vibration systems (1A, 1B) each whose vibration includes a radial vibration component (5A, 5B) with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator, said first vibration systems being symmetrical about said center of gravity of said vibrator, and a second vibration system (2A, 2B) whose vibration includes a circumferential vibration component (6A, 6B) with respect to an imaginary circle whose center is coincident with said center of gravity of said vibrator;

exciting means provided in said first vibration systems for exciting a driving vibration in said vibrator; and

detecting means provided in said 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.

29. The vibratory gyroscope as claimed in claim 28, wherein said turning axis intersects said specified plane at a right angle.

30. The vibratory gyroscope as claimed in claim 28, further comprising a base portion (11A) having a peripheral part (11a), and said first and second vibration systems extend from said peripheral part, respectively.

31. The vibratory gyroscope as claimed in claim 30, wherein said center of gravity of said vibrator is located inside of said peripheral part of said base portion.

32. The vibratory gyroscope as claimed in claim 31, wherein both of said first and second vibration systems extend from said peripheral part radially with respect to said center of gravity of said vibrator.

33. The vibratory gyroscope as claimed in claim 32, wherein said plurality of said first vibration systems are provided in positions which are substantially identical with each other after turning said positions around said center of gravity of said vibrator.

34. The vibratory gyroscope as claimed in claim 33, 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.

35. The vibratory gyroscope as claimed in claim 33, wherein each first vibration system comprises at least one first bending-vibration piece whose vibration includes at least said radial vibration component.

36. The vibratory gyroscope as claimed in claim 35, wherein said each first vibration system comprises a supporting portion extending from said base portion and said first bending-vibration piece extends in a direction intersecting the longitudinal direction of said supporting portion.

37. The vibratory gyroscope as claimed in claim 33, comprising a plurality of second vibration systems located in positions which are substantially identical with each other after turning said positions around said center of gravity of said vibrator.

38. The vibratory gyroscope as claimed in claim 31, wherein the center of gravity (GD) of said first vibration systems is located on or in the vicinity of said center of gravity of said vibrator.

39. The vibratory gyroscope as claimed in claim 31, wherein said vibrator comprises two first vibration systems and two second vibration systems, each first vibration system comprising a supporting portion protruding from said peripheral part and first bending-vibration piece or pieces intersecting said supporting portion, and each second vibration system comprising one second bending-vibration piece protruding from said peripheral part.

40. The vibratory gyroscope as claimed in claim 39, wherein said first vibration systems are located in positions which are diad-symmetrical with each other with respect to said center of gravity of said vibrator and said second bending-vibration pieces are located in positions which are diad-symmetrical with each other with respect to said center of gravity of said vibrator.

41. The vibratory gyroscope as claimed in claim 39, wherein each of said supporting portions bending-vibrates about its connection point to said peripheral part, each of said first bending-vibration pieces bending-vibrates about its connection point to said supporting portion, and each of said second bending-vibration pieces bending-vibrates about its connection point to said peripheral part.

42. The vibratory gyroscope as claimed in claim 41, wherein each supporting portion and each second bending-vibration piece bending-vibrate in opposite directions to each other in reverse phase around said center of gravity of said vibrator.

43. The vibratory gyroscope as claimed in claim 30, wherein each said first vibration system comprises at least one first bending-vibration piece whose vibration includes at least said radial vibration component.

44. The vibratory gyroscope as claimed in claim 43, wherein each said first vibration system comprises a supporting portion extending from said peripheral part of said base portion and said first bending-vibration piece extends in a direction intersecting the longitudinal direction of said supporting portion.

45. The vibratory gyroscope as claimed in claim 44, comprising a plurality of said second vibration systems located in positions which are substantially identical with each other after turning said positions around said center of gravity of said vibrator.

46. The vibratory gyroscope as claimed in claim 44, wherein said second vibration system comprises at least one second bending-vibration piece whose vibration includes at least said circumferential vibration component.

47. The vibratory gyroscope as claimed in claim 46, wherein said second bending-vibration piece protrudes from said peripheral part of said base portion radially with respect to said center of gravity of said vibrator.

48. The vibratory gyroscope as claimed in claim 47, wherein each of said supporting portions bending-vibrates about its connection point to said peripheral part, each of said first bending-vibration pieces bending-vibrates about its connection point to said supporting portion, and each of said second bending-vibration pieces bending-vibrates about its connection point to said peripheral part.

49. The vibratory gyroscope as claimed in claim 48, wherein each supporting portion and each second bending-vibration piece bending-vibrate in opposite directions to each other around said center of gravity of said vibrator.

50. The vibratory gyroscope as claimed in claim 30, comprising a plurality of second vibration systems located in positions which are substantially identical with each other after turning said positions around said center of gravity of said vibrator.

51. The vibratory gyroscope as claimed in claim 30, wherein said second vibration system comprises at least one second bending-vibration piece whose vibration includes at least said circumferential vibration component.

52. The vibratory gyroscope as claimed in claim 51, wherein said second bending-vibration piece protrudes from said peripheral part of said base portion radially with respect to said center of gravity of said vibrator.

53. The vibratory gyroscope as claimed in claim 28, comprising a thin plate made of a piezoelectric single crystal and electrodes formed on said thin plate.

54. The vibratory gyroscope as claimed in claim 53, wherein said piezoelectric single crystal is selected from the group consisting of single crystals of quartz, LiNbO₃, LiTaO₃, a solid solution of lithium niobate-lithium tantalate, langasite and lithium tetraborate.

56. The vibratory gyroscope of claim 28, wherein said first vibrating systems are symmetrical about a line passing through said center of gravity of said vibrator and said second vibration system is positioned along said line.