TRANSDUCER ARRANGEMENT

• US 20140355388A1
• Filed: 01/07/2013
• Published: 12/04/2014
• Est. Priority Date: 01/09/2012
• Status: Active Grant

• Current Assignee: BAE Systems Plc
• Original Assignee: BAE Systems Plc
• Inventors: Kent, Lionel William John, Bagshaw, John Martin, Rowe, Duncan Peter
• Granted Patent: US 9,307,325 B2
• Time in Patent Office: Days
• US Class Current: 367/140
• CPC Class Codes: B06B 3/00 Methods or apparatus specially adapted for transmitting mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
• CPC Class Codes: H04B 11/00 Transmission systems employing sonic, ultrasonic or infrasonic waves
• CPC Class Codes: H04B 13/00 Transmission systems characterised by the medium used for transmission, not provided for in groups H04B3/00 - H04B11/00
• 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
• CPC Class Codes: H04R 31/00 Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182
• CPC Class Codes: H10N 30/40 with electrical input and electrical output, e.g. functioning as transformers
• CPC Class Codes: Y10T 29/49005 Acoustic transducer

Abstract

There is disclosed a transducer apparatus for acoustic communications through a substrate at a predetermined centre frequency, the apparatus comprising: —an active piezoelectric element for generating an acoustic signal; an intermediate layer, having a surface for accommodating the piezoelectric element, and having a first array of protrusions on a surface opposite the surface for accommodating the piezoelectric element; and a second array of protrusions at the substrate, wherein the active piezoelectric element is mounted onto the intermediate layer, and the intermediate layer is secured in position relative to the substrate such that the first array of protrusions faces the second array of protrusions such that the acoustic signal may propagate through the first and second arrays. There are further disclosed a method of mounting such an apparatus and a plate suitable for use in the transducer apparatus.

Claims

1. A transducer apparatus for acoustic communications through a substrate at a predetermined centre frequency, the apparatus comprising:

an active piezoelectric element for generating an acoustic signal;

an intermediate layer, having a surface for accommodating the piezoelectric element, and having a first array of protrusions on a surface opposite the surface for accommodating the piezoelectric element; and

a second array of protrusions at a surface of the substrate,

wherein the active piezoelectric element is mounted onto the intermediate layer, and the intermediate layer is secured in position relative to the substrate such that the first array of protrusions faces the second array of protrusions such that the acoustic signal may propagate through the first and second arrays.

2. A transducer apparatus according to claim 1 wherein the first array of protrusions are dimensioned and arranged such that the distance between the median point on a first first-array protrusion and the median point on an adjacent first-array protrusion is less than the wavelength of an acoustic wave in the intermediate layer at the predetermined frequency;

and/or the second array of protrusions are dimensioned and arranged such that the distance between the median point on a first second-array protrusion and the median point on an adjacent second-array protrusion is less than the wavelength of an acoustic wave in the substrate at the predetermined frequency.

3. A transducer apparatus according to claim 1 wherein the first or second array of protrusions comprises binary protrusions, each binary protrusion extending generally perpendicularly from the surface at the substrate or intermediate layer and having a generally constantly-shaped cross section along the axis of the extension.

4. A transducer apparatus according to claim 3 wherein the constantly-shaped cross section is a rectangular cross section.

5. A transducer apparatus according to claim 1 wherein the first or second array of protrusions comprises multi-step protrusions each multi-step protrusion having a first step extending generally perpendicularly from the surface at the substrate or intermediate layer, the first step having a first shaped cross section, the first shaped cross section being generally constantly-shaped along the axis of the extension and having a second step extending from the first step, the second step having a second shaped cross section, the second shaped cross section being generally constantly-shaped along the axis of the extension, the second step having a smaller cross sectional area than the first.

6. A transducer apparatus according to claim 1 wherein the first or second array of protrusions comprises tapered protrusions, each tapered protrusion extending from the surface at the substrate or intermediate layer and having a base with a first cross section shape, and extending along the axis of the extension from the base to a second cross-section shape, and continuously tapering between the base and the second section shape.

7. A transducer apparatus according to claim 6 wherein the bases of the tapered protrusions are substantially adjacent and are arranged to tessellate.

8. A transducer apparatus according to claim 6 wherein the second cross-section shape is a point such that the protrusion has the form of a pyramid.

9. A transducer apparatus according to claim 1 wherein the predetermined centre frequency is within the range 1 MHz to 100 MHz.

10. A transducer apparatus according to claim 1 wherein a layer of adhesive is provided between the intermediate layer and the substrate, and the adhesive has a thickness equal to at least a third of the wavelength of the signal predetermined centre frequency in the adhesive.

11. A method of arranging a transducer unit at a substrate, for acoustic communications through the substrate, comprising:

i. forming a first array of protrusions at a surface of the substrate;

providing a transducer unit for generating or receiving an acoustic signal at a predetermined centre frequency;

forming a second array of protrusions upon a surface of the transducer unit; and

fixing the transducer unit relative to the substrate such that the transducer unit is arranged to receive/transmit acoustic signals via the first and second array of protrusions into/out of the substrate.

12. A method according to claim 11 wherein the transducer unit comprises an active piezoelectric element and an intermediate layer, and forming the second array of protrusions comprises forming the second array of protrusions on the intermediate layer.

13. A method according to claim 11 wherein forming the first and/or second array of protrusions is by embossing the respective surface of the transducer unit or substrate.

14. A method according to any of claim 11 wherein forming the first and/or second array of protrusions comprises:

attaching a covering at the surface of the substrate or intermediate layer;

forming the protrusions at the covering.

15. A method according to claim 14 wherein the substrate is steel and the covering is formed from copper.

16. A plate comprising an array of protrusions for mitigating acoustic impedance loss in a transducer apparatus operating at a predetermined centre-frequency, and in an environment comprising a predetermined medium, wherein the array of protrusions are dimensioned and arranged such that the distance between the median point on a first protrusion and the median point on an adjacent protrusion is less than the wavelength of an acoustic wave in the plate at the predetermined centre-frequency, and is less than the wavelength of an acoustic wave in the predetermined medium at the predetermined centre-frequency.

17. The plate according to claim 16 wherein the predetermined medium is fluid, and the plate is part of a sonar system.

18. The plate according to claim 16 wherein the protrusions are pyramid-shaped and arranged to tessellate at their bases.

19. The plate according to claim 18 wherein each pyramid has a height equal to or greater than 0.8 times the wavelength of the acoustic wave in the predetermined medium at the predetermined centre-frequency.

20. The plate according to claim 18 wherein each pyramid has a height equal to or greater than 1.5 times the wavelength of the acoustic wave in the predetermined medium at the predetermined centre-frequency.