Piezoelectric acoustic actuator

• US 6,717,337 B2
• Filed: 05/23/2001
• Issued: 04/06/2004
• Est. Priority Date: 05/23/2001
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Bucaro, Joseph A., Howarth, Thomas R., Tressler, James F.
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US09/862,345
• Publication Number:
  US 20020176592A1
• Time in Patent Office: 1,049 Days
• Field of Search: 310/311, 310/324, 310/326-328, 310/357, 310/367, 310/369
• US Class Current: 310/369
• CPC Class Codes: H04R 17/00 Piezoelectric transducers; Electrostrictive transducers piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners H10N30/00

Abstract

An acoustic actuator comprises a radially poled piezoelectric or electrostrictive drive element which is electroded on its inner and outer faces, and an acoustic diaphragm coupled to the upper surface of the piezoelectric drive element. As a voltage is applied to the electrodes, the piezoelectric drive element expands and contracts in the radial direction and the acoustic diaphragm displaces upward or downward, generating a sound wave. In an alternative embodiment, the piezoelectric or electrostrictive drive element is comprised of several subelements laid end to end and radially poled. In another embodiment, the piezoelectric or electrostrictive drive element is comprised of several subelements laid end to end which are thickness-poled reduced and internally biased oxide wafers of piezoelectric material.

Claims

1. An acoustic actuator, comprising:

an electrically active drive element,

said drive element having major inner and outer faces and upper and lower surfaces,

said drive element being poled in the radial direction,

an acoustic diaphragm mechanically attached to said drive element, and

an inner electrode disposed on said inner face of said drive element and an outer electrode disposed on said outer face of said drive element.

2. An acoustic projector as in claim 1, wherein said drive element is a piezoelectric or electrostrictive material.

3. An acoustic actuator as in claim 2, wherein said drive element is a member of the lead zirconate titanate family.

4. An acoustic actuator as in claim 1, wherein said inner electrode is a conductive metallic layer on said inner face of said drive element and said outer electrode is a conductive metallic layer on said outer face of said drive element.

5. An acoustic actuator as in claim 1, wherein said acoustic diaphragm is substantially planar.

6. An acoustic actuator as in claim 1, wherein said acoustic diaphragm has an dome shape.

7. An acoustic actuator as in claim 1, wherein said acoustic diaphragm comprises a thin flexible membrane or shell.

8. An acoustic actuator as in claim 7, wherein said acoustic diaphragm comprises a thermoplastic film.

9. An acoustic actuator as in claim 7, wherein said acoustic diaphragm comprises a polymer membrane.

10. An acoustic actuator as in claim 7, wherein said acoustic diaphragm comprises a multi-layer polymer membrane.

11. An acoustic actuator as in claim 10, wherein said multilayer polymer membrane comprises:

a layer of thermoplastic polyimide film,

a layer of polyamide film,

a layer of fiberglass cloth,

and a second layer of polyamide film.

12. An acoustic actuator as in claim 1, wherein said acoustic diaphragm is attached to said drive element with an adhesive disposed between said acoustic diaphragm and said upper surface of said drive element.

13. An acoustic actuator as in claim 1, wherein said inner and outer surfaces of said drive element are substantially circular.

14. An acoustic actuator as in claim 1, wherein said inner and outer faces of said drive element are elliptical.

15. An acoustic actuator as in claim 1, wherein said drive element comprises a plurality of subelements arranged end-to-end, said subelements poled to expand or contract in response to an applied electrical signal.

16. An acoustic actuator as in claim 1, further comprising a backing disposed opposite said acoustic diaphragm.

17. An acoustic actuator as in claim 16, wherein said backing comprises a polymer membrane.

18. An acoustic actuator as in claim 16, wherein said acoustic diaphragm has excess material which extends beyond said outer surface of said drive elements, and wherein said backing is attached to said acoustic diaphragm excess material.

19. An acoustic actuator, comprising:

electrically active thickness poled drive subelements laid end to end,

said drive subelements having major inner and outer faces and upper and lower surfaces,

said drive subelements made from a reduced and internally biased oxide wafer of piezoelectric material, and

an acoustic diaphragm mechanically attached to said drive elements.

20. An acoustic blanket comprising:

a plurality of electrically active drive elements,

each drive element having major inner and outer faces,

each drive element having an upper surface and a lower surface,

an electrode on said inner face and an electrode on said outer face of said drive element,

an acoustic sheet having indentations, each indentation comprising a film bubble sized to receive said drive elements.

21. An acoustic blanket as in claim 20, wherein said drive elements are mechanically attached to said acoustic sheet at said upper surface of said drive elements.

22. An acoustic blanket as in claim 20, further comprising electrical leads for connecting said electrodes to an external electrical power source.

23. An acoustic blanket as in claim 20, wherein said film bubbles comprise thin flexible film.

24. An acoustic blanket as in claim 20, wherein said film bubbles comprise a polymer membrane.

25. An acoustic blanket as in claim 21, wherein said film bubbles comprise a thermoplastic film.

26. An acoustic blanket as in claim 25, wherein said film bubbles comprise a thermoplastic polyimide film.

27. An acoustic blanket as in claim 20, wherein said film bubbles comprise:

a layer of thermoplastic polyimide film,

a layer of polyamide film,

a layer of fiberglass cloth,

and a second layer of polyamide film.

28. An acoustic blanket as in claim 22, wherein said acoustic sheet comprises:

a layer of thermoplastic polyimide film,

a layer of polyamide film,

and a layer of thermoplastic polyimide film.

29. An acoustic blanket as in claim 20, wherein said inner electrode comprises a conductive layer on said inner face of said drive element and said outer electrode comprises a conductive layer on said outer face of said drive element.

30. An acoustic blanket as in claim 20, further comprising a backing attached to said acoustic sheet.

31. An acoustic actuator, comprising:

an electrically active drive element,

the drive element having major inner and outer faces and upper and lower surfaces,

the drive element being poled in the radial direction, and

an acoustic diaphragm mechanically attached to the drive element, wherein the acoustic diaphragm includes a thin flexible multi-layer polymer membrane or shell.

32. An acoustic actuator as in claim 31, wherein the multi-layer polymer membrane or shell comprises:

a layer of thermoplastic polyimide film,

a layer of polyamide film,

a layer of fiberglass cloth,

and a second layer of polyamide film.

33. An acoustic actuator, comprising:

an electrically active drive element,

the drive element having major inner and outer faces and upper and lower surfaces,

the drive element being poled in the radial direction, and

an acoustic diaphragm mechanically attached to the drive element,

wherein the inner and outer faces of the drive element are elliptical.

34. An acoustic actuator as in claim 33, wherein the acoustic diaphragm is substantially planar.

35. An acoustic actuator as in claim 33, wherein the acoustic diaphragm has an dome shape.

36. An acoustic actuator as in claim 33, wherein the acoustic diaphragm comprises a thin flexible membrane or shell.

37. An acoustic actuator as in claim 33, wherein the acoustic diaphragm comprises a thermoplastic film.

38. An acoustic actuator as in claim 33, wherein the acoustic diaphragm comprises a polymer membrane.

39. An acoustic actuator as in claim 33, wherein the acoustic diaphragm comprises a multi-layer polymer membrane.

40. An acoustic actuator as in claim 33, wherein the multilayer polymer membrane comprises:

a layer of thermoplastic polyimide film,

a layer of polyamide film,

a layer of fiberglass cloth,

and a second layer of polyamide film.

41. An acoustic actuator as in claim 33, wherein the acoustic diaphragm is attached to the drive element with an adhesive disposed between the acoustic diaphragm and the upper surface or lower surface of the drive element.

42. An acoustic actuator as in claim 33, wherein the drive element includes a plurality of subelements arranged end-to-end, the subelements being poled to expand or contract in response to an applied electrical signal.

43. An acoustic actuator, comprising:

an electrically active drive element,

the drive element having major inner and outer faces and upper and lower surfaces,

the drive element being poled in the radial direction, and

an acoustic diaphragm mechanically attached to the drive element,

wherein the drive element comprises a plurality of subelements arranged end-to-end,

the subelements poled to expand or contract in response to an applied electrical signal.

44. An acoustic actuator as in claim 43, wherein the acoustic diaphragm is substantially planar.

45. An acoustic actuator as in claim 43, wherein the acoustic diaphragm has an dome shape.

46. An acoustic actuator as in claim 43, wherein the acoustic diaphragm includes a thin flexible membrane or shell.

47. An acoustic actuator as in claim 43, wherein the acoustic diaphragm includes a thermoplastic film.

48. An acoustic actuator as in claim 43, wherein the acoustic diaphragm includes a polymer membrane.

49. An acoustic actuator as in claim 43, wherein the acoustic diaphragm comprises a multi-layer polymer membrane.

50. An acoustic actuator as in claim 43, wherein the multilayer polymer membrane comprises:

a layer of thermoplastic polyimide film,

a layer of polyamide film,

a layer of fiberglass cloth,

and a second layer of polyamide film.

51. An acoustic actuator as in claim 43, wherein the acoustic diaphragm is attached to the drive element with an adhesive disposed between the acoustic diaphragm and the upper surface or lower surface of the drive element.

52. An acoustic actuator, comprising:

an electrically active drive element,

the drive element having major inner and outer faces and upper and lower surfaces,

the drive element being poled in the radial direction, and

an acoustic diaphragm mechanically attached to the drive element,

and a backing disposed opposite the acoustic diaphragm.

53. An acoustic actuator as in claim 52, wherein the backing includes a polymer membrane.

54. An acoustic actuator as in claim 52, wherein the acoustic diaphragm has excess material which extends beyond the outer face of the drive element, and wherein the backing is attached to the acoustic diaphragm excess material.

55. An acoustic actuator, comprising:

an electrically active drive element,

the drive element having major inner and outer faces and upper and lower surfaces,

the drive element being poled in the radial direction, and

an acoustic diaphragm mechanically attached to the drive element, wherein

the acoustic diaphragm comprises a thermoplastic film.

56. An acoustic actuator, comprising:

an electrically active drive element,

the drive element having major inner and outer faces and upper and lower surfaces,

the drive element being poled in the radial direction, and

an acoustic diaphragm mechanically attached to the drive element wherein

the acoustic diaphragm comprises a polymer membrane.