Multilayer piezoelectric transformer

• US 6,326,718 B1
• Filed: 06/02/2000
• Issued: 12/04/2001
• Est. Priority Date: 12/23/1999
• Status: Expired due to Term

• Current Assignee: Face International Corp.
• Original Assignee: Face International Corp.
• Inventors: Boyd, Clark Davis
• Primary Examiner(s): Dougherty, Thomas M.
• Application Number:
  US09/586,304
• Time in Patent Office: 550 Days
• Field of Search: 310/359
• US Class Current: 310/359
• CPC Class Codes: H10N 30/40 with electrical input and electrical output, e.g. functioning as transformers

Abstract

A multilayer piezoelectric transformer is provided using the longitudinal vibration modes for step-up voltage conversion applications. An input portion polarized to deform in a longitudinal plane is bonded to an output portion. The deformation of the input portion is mechanically coupled to the output portion, which deforms in the same longitudinal direction relative to the input portion. The output portion is polarized in the thickness direction relative its electrodes, and piezoelectrically generates a stepped-up output voltage.

Claims

1. A piezoelectric transformer, comprising:

a first input electroactive layer having first and second opposing electroded major faces and first and second opposing minor faces and polarized such that upon application of voltage across said first and second opposing electroded major faces, said first input electroactive layer deforms in a longitudinal direction parallel to said first and second opposing electroded major faces and perpendicular to said first and second opposing minor faces;

an output electroactive layer having first and second opposing major faces, first and second opposing electroded minor faces, third and fourth opposing minor faces, and a central output electrode bonded to said output electroactive layer between said first and second opposing electroded minor faces;

said output electroactive layer having a first output portion between said central output electrode and said first electroded minor face, said first output portion being polarized in a direction normal to said first electroded minor face;

said output electroactive layer having a second output portion between said central output electrode and said second electroded minor face, said second output portion being polarized in a direction normal to said second electroded minor face; and

a dielectric layer having first and second opposing major faces;

said first major face of said dielectric layer being bonded to said first electroded major face of said input electroactive layer;

said second major face of said dielectric layer being bonded to said first major face of said output electroactive layer;

wherein upon application of a voltage across said first and second electroded major faces of said input electroactive layer, said input electroactive layer deforms in said longitudinal direction;

and wherein upon said longitudinal deformation of said input electroactive layer, said bonded dielectric layer and said output electroactive layer mechanically strain in said longitudinal direction;

and wherein said mechanical strain of said output electroactive layer in said longitudinal direction piezoelectrically generates a first output voltage between said first electroded minor face and said central output electrode and a second output voltage between said second electroded minor face and said central output electrode.

2. The piezoelectric transformer of claim 1,

wherein a first distance between said central output electrode and said first or second electroded minor face is greater than a second distance between said first and second opposing major faces of said output electroactive layer.

3. The piezoelectric transformer of claim 2,

wherein said direction of poling of said first output portion is opposite said direction of poling of said second output portion.

4. The piezoelectric transformer of claim 3,

wherein said central output electrode comprises an electrode layer substantially bisecting said output electroactive layer in a plane parallel to said first and second electroded minor faces.

5. The piezoelectric transformer of claim 3,

wherein said central output electrode comprises a conductive band encircling a portion of said output electroactive layer on said first and second opposing major faces and said third and fourth minor faces, said encircled portion being substantially equidistant from each of said first and second electroded minor faces.

6. The piezoelectric transformer of claim 5, further comprising:

means for applying a first voltage of a first polarity across said first input electroactive layer, wherein application of said first voltage deforms said first input electroactive layer in a first direction parallel to said longitudinal direction; and

means for applying a second voltage having a second polarity opposite said first polarity across said first input electroactive layer, wherein application of said second voltage deforms said first input electroactive layer in a second opposite direction parallel to said longitudinal direction.

7. The piezoelectric transformer of claim 5, further comprising:

a second input electroactive layer having first and second opposing electroded major faces and polarized such that upon application of a voltage is across said first and second opposing electroded major faces, said second input electroactive layer deforms in said longitudinal direction parallel to said first and second opposing major faces;

said first electroded major face of said second input electroactive layer being bonded to said second electroded major face of said first input electroactive layer.

8. The piezoelectric transformer of claim 7, further comprising:

means for applying a first voltage across said first input electroactive layer, wherein application of said first voltage deforms said first input electroactive layer in a first direction parallel to said longitudinal direction; and

means for applying a second voltage across said second input electroactive layer, wherein application of said first voltage deforms said second input electroactive layer in a second opposite direction parallel to said longitudinal direction.

9. The piezoelectric transformer of claim 7,

wherein said direction of polarization of said first input electroactive layer is opposite said direction of polarization of said second input electroactive layer;

and wherein said first voltage and said second voltage have the same polarity.

10. The piezoelectric transformer of claim 7,

wherein said direction of polarization of said first input electroactive layer and said direction of polarization of said second input electroactive layer are the same;

and wherein said first voltage and said second voltage have opposite polarities.

11. The piezoelectric transformer of claim 7, further comprising:

a third input electroactive layer having first and second opposing electroded major faces and polarized such that upon application of a voltage is across said first and second opposing electroded major faces, said third input electroactive layer deforms in said longitudinal direction parallel to said first and second opposing major faces;

said first electroded major face of said third input electroactive layer being bonded to said second electroded major face of said second input electroactive layer.

12. The piezoelectric transformer of claim 11, further comprising:

means for applying a first voltage of a first polarity across said first input electroactive layer and said second input electroactive layer, wherein application of said first voltage deforms said first input electroactive layer and said second input electroactive layer in a first direction parallel to said longitudinal direction; and

means for applying a second voltage having a second polarity opposite said first polarity across said second input electroactive layer and said third input electroactive layer, wherein application of said second voltage deforms said second input electroactive layer and said third input electroactive layer in a second opposite direction parallel to said longitudinal direction.

13. The piezoelectric transformer of claim 11, further comprising:

a fourth input electroactive layer having first and second opposing electroded major faces and polarized such that upon application of a voltage is across said first and second opposing electroded major faces, said fourth input electroactive layer deforms in said longitudinal direction parallel to said first and second opposing major faces;

said first electroded major face of said fourth input electroactive layer being bonded to said second electroded major face of said third input electroactive layer.

14. The piezoelectric transformer of claim 11, further comprising:

means for applying a first voltage across said first input electroactive layer and said third input electroactive layer, wherein application of said first voltage deforms said first input electroactive layer and said third input electroactive layer in a first direction parallel to said longitudinal direction; and

means for applying a second voltage across said second input electroactive layer and said fourth input electroactive layer, wherein application of said second voltage deforms said second input electroactive layer and said fourth input electroactive layer in a second opposite direction parallel to said longitudinal direction.

15. The piezoelectric transformer of claim 11,

wherein said direction of polarization of said first input electroactive layer and said third input electroactive layer are opposite said direction of polarization of said second input electroactive layer and said fourth input electroactive layer;

and wherein said first voltage and said second voltage have the same polarity.

16. The piezoelectric transformer of claim 13,

wherein said direction of polarization of said first input electroactive layer, said second input electroactive layer, said third input electroactive layer and said fourth input electroactive layer are the same;

and wherein said first voltage and said second voltage have opposite polarities.

17. The piezoelectric transformer of claim 6,

wherein said means for applying said first and second voltages comprise means for applying said first and second voltages at a resonant frequency of said piezoelectric transformer;

and wherein a third distance between said first and second opposing minor faces of said first input electroactive layer comprises an integral multiple of half wavelengths of said resonant frequency of said piezoelectric transformer.

18. The piezoelectric transformer of claim 17,

wherein said first distance between said central electrode and said first or second electroded minor faces comprises an integral multiple of half wavelengths of said resonant frequency of said piezoelectric transformer.

19. The piezoelectric transformer of claim 6,

wherein said second distance between said first and second opposing major faces of said output electroactive layer is greater than a fourth distance between said first and second opposing major faces of said first input electroactive layer.