Acoustic transducer with impedance matching layer

Patent metadata

Field	Value
Publication number	US-2016016199-A1
Application number	US-201514713822-A
Country	US
Kind code	A1
Filing date	May 15, 2015
Priority date	Feb 15, 2011
Publication date	Jan 21, 2016
Grant date	—

Abstract

A piezoelectric transducer is mounted in a housing. An impedance matching layer is provided between the piezoelectric transducer and the housing. The impedance matching layer includes high-permittivity regions that have a first permittivity, and low-permittivity regions that separate the high-permittivity regions and have a second permittivity. The second permittivity is lower than the first permittivity.

First claim

What is claimed is:

1 . A device comprising:
a piezoelectric transducer, the transducer having N independent transducer regions wherein N is an integer, each of the N independent transducer regions having a thickness, each of the N independent transducer regions having an acoustic impedance AIT, each of the N independent transducer regions being independently excitable to oscillate in the thickness mode when electrically excited by a potential difference applied across the thickness; a first impedance matching layer having an acoustic impedance AI1 between AIT and a borehole fluid acoustic impedance AIBF, the first impedance matching layer being situated such that an acoustic signal emitted by the piezoelectric transducer will pass through the first impedance matching layer, the first impedance matching layer comprising:
high-permittivity regions that match and overlay the N independent transducer regions and have a first permittivity, and
low-permittivity regions that separate the high-permittivity regions and have a second permittivity wherein the second permittivity is lower than the first permittivity; and
a second impedance matching layer having an acoustic impedance AI2 between AI1 and AIBF, the second impedance matching layer being situated in the device such that an acoustic signal emitted by the transducer will pass through the second impedance matching layer after it passes through the first impedance matching layer; wherein the first impedance matching layer has N independent first impedance matching layer regions that match and overlay the N independent transducer regions.

2 . The device of claim 1 wherein the low-permittivity regions are formed by cuts in the first impendence matching layer.

3 . The device of claim 1 wherein the low-permittivity regions impede displacement currents.

4 . The device of claim 1 wherein the low-permittivity regions act as series elements between the high-permittivity regions.

5 . The device of claim 1 wherein the low-permittivity regions cause the device to present a smaller load than without the low-permittivity regions.

6 . A method comprising:
emitting an acoustic pulse from a piezoelectric transducer, the transducer having N independent transducer regions wherein N is an integer, each of the N independent transducer regions having a thickness, each of the N independent transducer regions having an acoustic impedance AIT, each of the N independent transducer regions being independently excitable to oscillate in the thickness mode when electrically excited by a potential difference applied across the thickness; passing the acoustic pulse through a first impedance matching layer having an acoustic impedance AI1 between AIT and a borehole fluid acoustic impedance AIBF, the first impedance matching layer comprising:
high-permittivity regions that match and overlay the N independent transducer regions and have a first permittivity, and
low-permittivity regions that separate the high-permittivity regions and have a second permittivity wherein the second permittivity is lower than the first permittivity; and
passing the acoustic pulse that has passed through the first impedance matching layer through a second impedance matching layer having an acoustic impedance AI2 between AI1 and AIBF.

7 . The method of claim 6 wherein the low-permittivity regions are formed by cuts in the first impendence matching layer.

8 . The method of claim 6 wherein the low-permittivity regions impede displacement currents.

9 . The method of claim 6 wherein the low-permittivity regions act as series elements between the high-permittivity regions.

10 . The method of claim 6 wherein the low-permittivity regions cause the device to present a smaller load than without the low-permittivity regions.

11 . An apparatus comprising:
a housing; a piezoelectric transducer mounted in the housing; and an impedance matching layer provided between the piezoelectric transducer and the housing, the impedance matching layer comprising:
high-permittivity regions that have a first permittivity, and
low-permittivity regions that separate the high-permittivity regions and have a second permittivity wherein the second permittivity is lower than the first permittivity.

12 . The device of claim 11 wherein the low-permittivity regions are formed by cuts in the impendence matching layer.

13 . The device of claim 11 wherein the low-permittivity regions impede displacement currents.

14 . The device of claim 11 wherein the low-permittivity regions act as series elements between the high-permittivity regions.

15 . The device of claim 11 wherein the low-permittivity regions cause the device to present a smaller load than without the low-permittivity regions.

16 . The device of claim 11 wherein the impedance matching layer comprises a plurality of slots extending therethrough, said slots also extending partially through the piezoelectric transducer.

Assignees

• Halliburton Energy Services Inc

Inventors

• Goodman George David
• Maki Voldi E

Classifications

• G01V1/159

  using piezoelectric or magnetostrictive driving means (generating mechanical vibrations by using piezoelectric or magnetostrictive effect in general, B06B1/06, B06B1/08) · CPC title

• G10K11/02

  Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators · CPC title

• B06B1/0625 Primary

  Annular array · CPC title

• B06B1/067 Primary

  which is used as, or combined with, an impedance matching layer · CPC title

• G01V1/40

  specially adapted for well-logging · CPC title