Piezoelectric transformer

• US 5,861,704 A
• Filed: 05/30/1997
• Issued: 01/19/1999
• Est. Priority Date: 05/30/1996
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Isobe, Kiyokazu, Kitami, Tsuyoshi
• Primary Examiner(s): Budd, Mark O.
• Assistant Examiner(s): Williams, Timothy A.
• Application Number:
  US08/866,329
• Time in Patent Office: 599 Days
• Field of Search: 310/316, 310/317, 310/358, 310/357, 310/359, 310/318, 310/369, 310/366
• US Class Current: 310/369
• CPC Class Codes: H10N 30/40 with electrical input and electrical output, e.g. functioning as transformers

Abstract

There is provided a piezoelectric transformer including (a) a cylindrical body made of piezoelectric material and longitudinally defining a driven section and a voltage generating section, the voltage generating section being polarized in one of directions in a direction of a longitudinal axis of the cylindrical body, (b) a pair of first electrodes formed at a curved surface of the cylindrical body in the driven section and defining a plurality of regions in the driven section in a direction of a longitudinal axis of the cylindrical body, the first electrodes being electrically isolated with each other, the regions being polarized so that every other regions are polarized in opposite directions in a direction of a longitudinal axis of the cylindrical body, the pair of first electrodes comprising a plurality of strip-shaped electrodes wound around the cylindrical body and disposed in parallel with one another in a direction of a longitudinal axis of the cylindrical body, every other strip-shaped electrodes being in electrical communication with one another so that they have a common voltage, and (c) a second electrode cooperating with one of the first electrodes located closer to the voltage generating section to make a pair therewith. In accordance with the above mentioned piezoelectric transformer, it is possible to prevent edges of a piezoelectric body from being chipped, because of its cylindrical shape. Thus, it is also possible to prevent destruction of a transformer originated from chipping thereof, resulting in higher reliability of a piezoelectric transformer.

Claims

1. A piezoelectric transformer comprising:

(a) a piezoelectric body made of piezoelectric material and longitudinally defining a driven section and a voltage generating section, said piezoelectric body being cylindrical in shape;

(b) a pair of input electrodes formed at a single curved surface of said piezoelectric body in said driven section for receiving ac voltage to oscillate said piezoelectric body to cause said piezoelectric body to produce a voltage; and

(c) an output electrode cooperating with one of said input electrodes to introduce the produced voltage therethrough.

2. The piezoelectric transformer as set forth in claim 1, wherein said input electrodes receive ac voltage having a frequency which causes longitudinal oscillation generated in said piezoelectric body to make first or higher order resonance in said piezoelectric body.

3. A piezoelectric transformer comprising:

(a) a solid cylindrical body made of piezoelectric material and longitudinally defining a driven section and a voltage generating section,

said voltage generating section being polarized in one of directions in a direction of a longitudinal axis of said cylindrical body;

(b) a pair of first electrodes formed at a curved surface of said cylindrical body in said driven section and defining a plurality of regions in said driven section in a direction of a longitudinal axis of said cylindrical body,

said first electrodes being electrically isolated with each other,

said regions being polarized so that every other regions are polarized in opposite directions in a direction of a longitudinal axis of said cylindrical body; and

(c) a second electrode cooperating with one of said first electrodes located closer to said voltage generating section to make a pair therewith.

4. The piezoelectric transformer as set forth in claim 3, wherein said driven section includes one of end surfaces of said cylindrical body and said voltage generating section includes the other, end surface and said second electrode is formed at said other end surface of said cylindrical body.

5. The piezoelectric transformer as set forth in claim 4, wherein said second electrode is formed at a curved surface and adjacent to said other end surface of said cylindrical body in place of being formed at said other end surface of said cylindrical body.

6. A piezoelectric transformer comprising:

(a) a solid cylindrical body made of piezoelectric material and longitudinally defining a driven section and a voltage generating section, said voltage generating section being polarized in one of directions in a direction of a longitudinal axis of said cylindrical body;

(b) a pair of first electrodes formed at a curved surface of said cylindrical body in said driven section and defining a plurality of regions in said driven section in a direction of a longitudinal axis of said cylindrical body,

said first electrodes being electrically isolated with each other, said regions being polarized so that adjacent regions are polarized in opposite directions in a direction of a longitudinal axis of said cylindrical body,

said pair of first electrodes comprising a plurality of strip-shaped electrodes wound around said cylindrical body and disposed in parallel with one another in a direction of a longitudinal axis of said cylindrical body, every other strip-shaped electrodes being in electrical communication with one another so that they have a common voltage; and

(c) a second electrode cooperating with one of said first electrodes located closer to said voltage generating section to make a pair therewith.

7. The piezoelectric transformer as set forth in claim 6, wherein said strip-shaped electrodes have the same width.

8. The piezoelectric transformer as set forth in claim 6, wherein said strip-shaped electrodes are equally spaced with one another in a direction of a longitudinal axis of said cylindrical body.

9. The piezoelectric transformer as set forth in claim 6, said every other strips-shaped electrodes are connected with one another by a wiring.

10. The piezoelectric transformer as set forth in claim 6, wherein said first electrodes receive ac voltage having a frequency which causes longitudinal oscillation generated in said cylindrical body to make first or higher order resonance in said cylindrical body.

11. The piezoelectric transformer as set forth in claim 6, wherein said cylindrical body has a diameter equal to a height thereof.

12. The piezoelectric transformer as set forth in claim 6 wherein said first and second electrodes are formed by curved-surface printing silver paste around said cylindrical body, and baking said silver paste.

13. The piezoelectric transformer as set forth in claim 6, wherein said driven section includes one of end surfaces of said cylindrical body and said voltage generating section includes the other, and said second electrode is formed at said other end surface of said cylindrical body.

14. The piezoelectric transformer as set forth in claim 13, wherein said second electrode is formed at a curved surface and adjacent to said other end surface of said cylindrical body in place of being formed at said other end surface of said cylindrical body.

15. A piezoelectric transformer comprising:

(a) a solid cylindrical body made of piezoelectric material and longitudinally defining a driven section and a voltage generating section, said voltage generating section being polarized in one of directions in a direction of a longitudinal axis of said cylindrical body;

(b) a pair of first electrodes formed at a curved surface of said cylindrical body in said driven section and defining a plurality of regions in said driven section in a direction of a longitudinal axis of said cylindrical body,

said first electrodes being electrically isolated with each other,

said regions being polarized so that every other regions are polarized in opposite directions in a direction of a longitudinal axis of said cylindrical body,

each of said pair of first electrodes comprising a plurality of finger electrodes wound circumferentially around said cylindrical body and disposed in parallel with one another in a direction of a longitudinal axis of said cylindrical body, said finger electrodes having ends spaced away from each other, and a connection electrode extending between said ends of finger electrodes of the associated first electrode in a direction of a longitudinal axis of said cylindrical body and connecting said finger electrodes thereto, said finger electrodes of said pair of first electrodes being alternately arranged in parallel with each other; and

(c) a second electrode cooperating with one of said first electrodes located closer to said voltage generating section to make a pair therewith.

16. The piezoelectric transformer as set forth in claim 15, wherein said finger electrodes have the same width.

17. The piezoelectric transformer as set forth in claim 15, wherein said finger electrodes are equally spaced with one another in a direction of a longitudinal axis of said cylindrical body.

18. The piezoelectric transformer as set forth in claim 15, wherein said first electrodes receive ac voltage having a frequency which causes longitudinal oscillation generated in said cylindrical body to make first or higher order resonance in said cylindrical body.

19. The piezoelectric transformer as set forth in claim 15 wherein said first and second electrodes are formed by curved-surface printing silver paste around said cylindrical body, and baking said silver paste.

20. The piezoelectric transformer as set forth in claim 15, wherein said driven section includes one of end surfaces of said cylindrical body and said voltage generating section includes the other, and said second electrode is formed at said other end surface of said cylindrical body.

21. The piezoelectric transformer as set forth in claim 20, wherein said second electrode is formed at a curved surface and adjacent to said other end surface of said cylindrical body in place of being formed at said other end surface of said cylindrical body.

22. A piezoelectric transformer comprising:

(a) a cylindrical body made of piezoelectric material and longitudinally defining a driven section and a voltage generating section, said voltage generating section being polarized in one of directions in a direction of a longitudinal axis of said cylindrical body;

(b) a pair of first electrodes formed at a curved surface of said cylindrical body in said driven section and defining a plurality of regions in said driven section in a direction of a longitudinal axis of said cylindrical body,

said first electrodes being electrically isolated with each other,

said regions being polarized so that adjacent regions are polarized in opposite directions in a direction of a longitudinal axis of said cylindrical body,

each of said pair of first electrodes comprising a spiral electrode; and

(c) a second electrode cooperating with one of said first electrodes located closer to said voltage generating section to make a pair therewith.

23. The piezoelectric transformer as set forth in claim 22, wherein said first electrodes receive ac voltage having a frequency which causes longitudinal oscillation generated in said cylindrical body to make first or higher order resonance in said cylindrical body.

24. The piezoelectric transformer as set forth in claim 22 wherein said first and second electrodes are formed by curved-surface printing silver paste around said cylindrical body, and baking said silver paste.

25. The piezoelectric transformer as set forth in claim 22, wherein said driven section includes one of end surfaces of said cylindrical body and said voltage generating section includes the other, and said second electrode is formed at said other end surface of said cylindrical body.

26. The piezoelectric transformer as set forth in claim 25, wherein said second electrode is formed at a curved surface and adjacent to said other end surface of said cylindrical body in place of being formed at said other end surface of said cylindrical body.

27. A piezoelectric transformer comprising:

(a) a cylindrical body made of piezoelectric material and longitudinally defining two driven sections and a voltage generating section sandwiched between said driven sections, each of said driven sections including an end surface of said cylindrical body,

said voltage generating section being polarized in one of directions in a direction of a longitudinal axis of said cylindrical body;

(b) two pairs of first electrodes each of which is formed at a curved surface of said cylindrical body in each of said driven sections and defines a plurality of regions in each of said driven sections in a direction of a longitudinal axis of said cylindrical body,

said first electrodes in each of said pairs being electrically isolated with each other,

said regions in each of said driven sections being polarized so that adjacent regions are polarized in opposite directions in a direction of a longitudinal axis of said cylindrical body; and

(c) a second electrode formed in said voltage generating section, said second electrode cooperating with first electrodes located closer to said voltage generating section to make a pair therewith.

28. The piezoelectric transformer as set forth in claim 27, wherein said regions in said driven sections are polarized symmetrically about said second electrode.

29. The piezoelectric transformer as set forth in claim 27 further comprising a plurality of lead wires for electrically connecting said piezoelectric transformer to an external terminal, said lead wires being connected to said piezoelectric transformer at nodes established in said cylindrical body when ac voltage is applied to said driven sections to thereby longitudinally oscillate said cylindrical body.

30. A piezoelectric transformer comprising:

(a) a cylindrical body made of piezoelectric material and longitudinally defining two driven sections and a voltage generating section sandwiched between said driven sections, each of said driven sections including an end surface of said cylindrical body,

said voltage generating section being polarized in one of directions in a direction of a longitudinal axis of said cylindrical body;

(b) two pairs of first electrodes each of which is formed at a curved surface of said cylindrical body in each of said driven sections and defines a plurality of regions in each of said driven sections in a direction of a longitudinal axis of said cylindrical body,

said first electrodes in each of said pairs being electrically isolated with each other,

said regions in each of said driven sections being polarized so that adjacent regions are polarized in opposite directions in a direction of a longitudinal axis of said cylindrical body,

each of said pairs of first electrodes comprising a plurality of strip-shaped electrodes wound around said cylindrical body and disposed in parallel with one another in a direction a longitudinal axis of said cylindrical body, every other strip-shaped electrodes being in electrical communication with one another so that they have a common voltage; and

(c) a second electrode comprising a strip-shaped electrode wound around said cylindrical body at the longitudinal midpoint thereof,

said second electrode cooperating with first electrodes located closer to said voltage generating section to make a pair therewith.

31. The piezoelectric transformer as set forth in claim 30, wherein said strip-shaped electrodes have the same width.

32. The piezoelectric transformer as set forth in claim 30, wherein said strip-shaped electrodes are equally spaced with one another in a direction of a longitudinal axis of said cylindrical body.

33. The piezoelectric transformer as set forth in claim 30, said every other strips-shaped electrodes are connected with one another by a wiring.

34. The piezoelectric transformer as set forth in claim 30, wherein said first electrodes receive ac voltage having a frequency which causes longitudinal oscillation generated in said cylindrical body to make first or higher order resonance in said cylindrical body.

35. The piezoelectric transformer as set forth in claim 30, wherein said cylindrical body has a diameter equal to a height thereof.

36. The piezoelectric transformer as set forth in claim 30 wherein said first and second electrodes are formed by curved-surface printing silver paste around said cylindrical body, and baking said silver paste.

37. The piezoelectric transformer as set forth in claim 30, wherein said regions in said driven sections are polarized symmetrically about said second electrode.

38. The piezoelectric transformer as set forth in claim 30 further comprising a plurality of lead wires for electrically connecting said piezoelectric transformer to an external terminal, said lead wires being connected to said piezoelectric transformer at nodes established in said cylindrical body when ac voltage is applied to said driven sections to thereby longitudinally oscillate said cylindrical body.

39. A piezoelectric transformer comprising:

(a) a cylindrical body made of piezoelectric material and longitudinally defining two driven sections and a voltage generating section sandwiched between said driven sections, each of said driven sections including an end surface of said cylindrical body,

said voltage generating section being polarized in one of directions in a direction of a longitudinal axis of said cylindrical body;

(b) two pairs of first electrodes each of which is formed at a curved surface of said cylindrical body in each of said driven sections and defines a plurality of regions in each of said driven sections in a direction of a longitudinal axis of said cylindrical body,

said first electrodes in each of said pairs being electrically isolated with each other,

said regions in each of said driven sections being polarized so that adjacent regions are polarized in opposite directions in a direction of a longitudinal axis of said cylindrical body,

each of said pairs of first electrodes comprising a plurality of finger electrodes wound circumferentially around said cylindrical body and disposed in parallel with one another in a direction of a longitudinal axis of said cylindrical body, said finger electrodes having ends spaced away from each other, and a connection electrode extending between said ends of finger electrodes of the associated first electrode in a direction of a longitudinal axis of said cylindrical body and connecting said finger electrodes thereto, said finger electrodes of said pair of first electrodes being alternately arranged in parallel with each other; and

(c) a second electrode comprising a strip-shaped electrode wound around said cylindrical body at the longitudinal midpoint thereof,

said second electrode cooperating with first electrodes located closer to said voltage generating section to make a pair therewith.

40. The piezoelectric transformer as set forth in claim 39, wherein said regions in said driven sections are polarized symmetrically about said second electrode.

41. The piezoelectric transformer as set forth in claim 39 further comprising a plurality of lead wires for electrically connecting said piezoelectric transformer to an external terminal, said lead wires being connected to said piezoelectric transformer at nodes established in said cylindrical body when ac voltage is applied to said driven sections to thereby longitudinally oscillate said cylindrical body.

42. A piezoelectric transformer comprising:

(a) a cylindrical body made of piezoelectric material and longitudinally defining two driven sections and a voltage generating section sandwiched between said driven sections, each of said driven sections including an end surface of said cylindrical body;

(b) two pairs of first electrodes each of which is formed at a curved surface of said cylindrical body in each of said driven sections and defines a plurality of regions in each of said driven sections in a direction of a longitudinal axis of said cylindrical body,

said first electrodes in each of said pairs being electrically isolated with each other,

said regions in each of said driven sections being polarized so that adjacent regions are polarized in opposite directions in a direction of a longitudinal axis of said cylindrical body,

each of said first electrodes comprising a spiral electrode; and

(c) a second electrode comprising a strip-shaped electrode wound around said cylindrical body at the longitudinal midpoint thereof,

said second electrode cooperating with first electrodes located closer to said voltage generating section to make a pair therewith.

43. The piezoelectric transformer as set forth in claim 42, wherein said regions in said driven sections are polarized symmetrically about said second electrode.

44. The piezoelectric transformer as set forth in claim 42 further comprising a plurality of lead wires for electrically connecting said piezoelectric transformer to an external terminal, said lead wires being connected to said piezoelectric transformer at nodes established in said cylindrical body when ac voltage is applied to said driven sections to thereby longitudinally oscillate said cylindrical body.

45. A support for supporting a piezoelectric transformer therewith,

said piezoelectric transformer comprising:

(a) a cylindrical body made of piezoelectric material longitudinally defining a driven section and a voltage generating section;

(b) a pair of input electrodes formed at a single curved surface of said cylindrical body in said driven section for receiving ac voltage to oscillate said cylindrical body to cause said cylindrical body to produce a voltage; and

(c) an output electrode cooperating with one of said input electrodes to introduce said voltage therethrough,

said support being made of resilient, electrically insulating material and supporting said piezoelectric transformer at nodes established in said cylindrical body when ac voltage is applied to said driven section to thereby longitudinally oscillate said cylindrical body.

46. A support for supporting a piezoelectric transformer therewith,

said piezoelectric transformer comprising:

(a) a cylindrical body made of piezoelectric material longitudinally defining a driven section and a voltage generating section;

(b) a pair of first electrodes formed at a curved surface of said cylindrical body in said driven section for receiving ac voltage to oscillate said cylindrical body to cause said cylindrical body to produce a voltage; and

(c) a second electrode cooperating with one of said first electrodes to introduce said voltage therethrough,

said support comprising;

(a) an enclosure through which said cylindrical body can be inserted; and

(b) resilient, electrically insulating material to be sandwiched between an inner surface of said enclosure and an outer surface of said cylindrical body.

47. The support as set forth in claim 46 further comprising a housing in which said enclosure is fixed to said housing.

48. The support as set forth in claim 46, wherein said enclosure is ring-shaped.

49. The support as set forth in claim 46, wherein said insulating material is silicone resin.

50. The support as set forth in claim 46, wherein said support supports said piezoelectric transformer at a longitudinal midpoint of said cylindrical body.

51. A support for supporting a piezoelectric transformer therewith,

said piezoelectric transformer comprising:

(a) a cylindrical body made of piezoelectric material longitudinally defining a driven section and a voltage generating section;

(b) a pair of first electrodes formed at a curved surface of said cylindrical body in said driven section for receiving ac voltage to oscillate said cylindrical body to cause said cylindrical body to produce a voltage; and

(c) a second electrode cooperating with one of said first electrodes to introduce said voltage therethrough,

said support comprising a plurality of supporting members made of resilient, electrically conductive material and supporting said piezoelectric transformer at said first and second electrodes therewith, said first and second electrodes being in electrical communication with an external terminal through said supporting members.

52. A support for supporting a piezoelectric transformer therewith,

said piezoelectric transformer comprising:

(a) a cylindrical body made of piezoelectric material longitudinally defining a driven section and a voltage generating section;

(b) a pair of first electrodes formed at a curved surface of said cylindrical body in said driven section for receiving ac voltage to oscillate said cylindrical body to cause said cylindrical body to produce a voltage; and

(c) a second electrode cooperating with one of said first electrodes to introduce said voltage therethrough,

said support comprising;

(a) an enclosure made of electrically insulating material for enclosing said piezoelectric transformer therein, said enclosure being formed at an outer wall thereof with a plurality holes; and

(b) resilient, electrically conductive material filled in said holes and making contact with said first electrodes, which are in electrical connection with an external terminal through said electrically conductive material.

53. The support as set forth in claim 52, wherein said holes comprising first and second sets of holes, each of said first and second sets of holes being formed in alignment with each of said first electrodes.

54. The support as set forth in claim 52, wherein said enclosure is rectangular in shape.

55. The support as set forth in claim 52, wherein said enclosure is circular in shape.

56. The support as set forth in claim 53, wherein said enclosure is rectangular in shape, said first and second sets of holes being formed with each of planes of said enclosure facing each other, said resilient, electrically conductive material filled in said first and second sets of holes being in electrical connection with each other, respectively.

57. The support as set forth in claim 56, wherein said planes make tangential contact with said cylindrical body.

58. The support as set forth in claim 52, wherein said resilient, electrically conductive material is silicone rubber.