Ultrasonic transducer array incorporating an array of slotted transducer elements

• US 6,014,898 A
• Filed: 06/09/1997
• Issued: 01/18/2000
• Est. Priority Date: 01/29/1993
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: Parallel Design, Inc (GE Aerospace)
• Inventors: Finsterwald, P. Michael, Just, Ricky Gail, Douglas, Stephen Joseph
• Primary Examiner(s): Williams, Hezron
• Assistant Examiner(s): Kwok, Helen C.
• Application Number:
  US08/871,211
• Time in Patent Office: 953 Days
• Field of Search: 73/632, 73/642, 73/644, 73/641, 310/334, 310/336, 310/322, 702/37, 600/447, 600/459
• US Class Current: 73/642
• CPC Class Codes: B06B 1/0622 on one surface
• CPC Class Codes: B06B 1/0633 Cylindrical array
• CPC Class Codes: B06B 1/0692 with a continuous electrode on one side and a plurality of electrodes on the other side
• CPC Class Codes: B06B 2201/20 Application to multi-element transducer
• CPC Class Codes: B06B 2201/50 Application to a particular transducer type
• CPC Class Codes: B06B 2201/56 Foil type, e.g. PVDF
• CPC Class Codes: G10K 11/32 characterised by the shape of the source
• CPC Class Codes: Y10T 29/42 Piezoelectric device making

Abstract

An ultrasonic transducer array having a plurality of transducer elements aligned along an array axis in an imaging plane. Each transducer element includes a piezoelectric layer and one or more acoustic matching layers. The piezoelectric layer has a concave front surface overlayed by a front electrode and a rear surface overlayed by a rear electrode. The shape of each transducer element is selected such that it is mechanically focused into the imaging plane. A backing support holds the plurality of transducer elements in a predetermined relationship along the array axis such that each element is mechanically focused in the imaging plane.

Claims

1. An ultrasonic transducer array for testing a body, comprising:

a plurality of transducer elements aligned along an array axis in an imaging plane, each of the plurality of transducer elements including

a piezoelectric layer having a front surface overlaid by a front electrode and a rear surface overlaid by a rear electrode, the front surface being interrupted by a series of slots arranged in directions substantially parallel with the array axis,

a first acoustic matching layer mounted in front of the front surface of the piezoelectric layer, and

an electrically conductive path across the series of slots of the piezoelectric layer,

wherein the piezoelectric layer and at least a portion of the first acoustic matching layer are spaced from the adjacent transducer elements; and

a backing support that supports the plurality of transducer elements in the aligned, spaced-apart relationship along the array axis.

2. The ultrasonic transducer array of claim 1, and further comprising means for focusing each of the plurality of transducer elements in a plane perpendicular to the array axis.

3. The ultrasonic transducer array of claim 2, wherein the means for focusing is an acoustic lens.

4. The ultrasonic transducer array of claim 2, wherein the means for focusing is provided by a concave shape for the front surfaces of the piezoelectric layer and the acoustic matching layer for each transducer element, in directions perpendicular to the array axis.

5. The ultrasonic transducer array of claim 1, wherein each of the plurality of transducer elements further includes a second acoustic matching layer mounted to a front surface of the first acoustic matching layer.

6. The ultrasonic transducer array of claim 5, wherein the first and second acoustic matching layers both have substantially uniform thicknesses.

7. The ultrasonic transducer array of claim 1, wherein the first acoustic matching layer has a substantially uniform thickness.

8. The ultrasonic transducer array of claim 1, wherein a flexible signal conductor is attached to the rear electrode of each of the plurality of transducer elements and a flexible ground conductor is attached to the front electrode of each of the plurality of transducer elements.

9. The ultrasonic transducer array of claim 8, wherein each of the plurality of transducer elements is divided into subelements, with the subelements electrically connected in parallel.

10. The ultrasonic transducer array of claim 1, further comprising a dielectric material forming an outer face layer for the plurality of transducer elements.

11. The ultrasonic transducer array of claim 1, wherein the spaces between adjacent transducer elements is filled with a low impedance acoustically attenuative material.

12. The ultrasonic transducer array of claim 1, wherein the front and rear electrodes each include an inner layer of nickel and an outer layer of copper.

13. The ultrasonic transducer array of claim 1, wherein the electrically conductive path is an electrically conductive layer between the piezoelectric layer and the acoustic matching layer of each transducer element.

14. The ultrasonic transducer array of claim 1, wherein:

the acoustic matching layer is formed of an electrically conductive material; and

the electrically conductive path is provided by the acoustic matching layer.

15. The ultrasonic transducer array of claim 1, and further comprising an elastomeric filler material located in the slots, to acoustically isolate the adjacent segments.

16. The ultrasonic transducer array of claim 15, wherein the elastomeric filler material is an epoxy material.

17. The ultrasonic transducer array of claim 1, wherein the piezoelectric layer of each transducer element is a PZT-based material.

18. The ultrasonic transducer array of claim 1, wherein the piezoelectric layer of each transducer element is a PVDF-based material.

19. The ultrasonic transducer array of claim 1, wherein the piezoelectric layer of each transducer element is a PMN-based material.

20. The ultrasonic transducer array of claim 1, wherein the first acoustic matching layer of each of the plurality of transducer elements in the array is completely spaced apart from the first acoustic matching layers of the adjacent transducer elements in the array.

21. The ultrasonic transducer array of claim 1, wherein the array axis is linear.

22. The ultrasonic transducer array of claim 1, wherein the array axis is curvilinear.

23. The ultrasonic transducer array of claim 1, wherein the array axis includes linear and curvilinear sections.

24. The ultrasonic transducer array of claim 1, wherein the slots arranged in each transducer element are substantially uniformly spaced.

25. The ultrasonic transducer array of claim 1, wherein the slots arranged in each transducer element are substantially randomly spaced, between a predetermined minimum spacing and a predetermined maximum spacing.