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Patent US4961252A successfully refreshed from Google Patents.
US4961252A
Expired / Lapsed
US
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Means and method for nonuniform poling of piezoelectric transducers
Assignee: Iowa State University Research Foundation Inc
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Filing: 1989-12-08
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Granted: 1990-10-09
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Expires: 2009-12-08
Abstract
Abstract An apparatus and method for nonuniform poling of piezoelectric transducers includes machining one or more indentation into an end of a piezoelectric rod and cutting the rod to present a thickened disk shape. Highly electrically conductive material is deposited on at least the indentations in the one end and on at least portions of the opposite face of the member. One or more electrodes are configured to matingly fit within the indentations on the one face of the disk, with a like number of electrodes being positionable on the opposite face of the material. Electrical power is then applied to the electrodes in desired amounts, polarity, and duration. The indentations vary the electrical field produced within the piezoelectric material to produce nonuniform poling in the material. The thick disk is then cut to remove the indentations and to present a thin, flat two sided disk for installation in a conventional piezoelectric transducer probe. The indentations are selected to produce poling in accordance with desired transducer response profiles such as Gaussian or Bessel functions.
Inventors
- 👤 David K. Hsu
- 👤 Frank J. Margetan
- 👤 Michael D. Hasselbusch
- 👤 Samuel J. Wormley
- 👤 Michael S. Hughes
- 👤 Donald O. Thompson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:20
CPC Classifications
G; G01; G01N; G01N29/00; G01N29/34; G01N29/346; G01N29/04; G01N29/06; G01N29/0609; G01N29/22; G01N29/24; G01N29/2437; G01N29/245; G01N29/2475; H; H10; H10N; H10N30/00; H10N30/01; H10N30/04; H10N30/045; G01N2291/00; G01N2291/04; G01N2291/042; G01N2291/0421; Y; Y10; Y10T; Y10T29/00; Y10T29/42
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
119 words
A method for nonuniform poling of a piezoelectric transducer comprising: altering a flat first surface of a piezoelectric material to produce at least one indentation; cutting the piezoelectric material to present a opposite second surface generally parallel with the first surface; bonding a highly electrically conductive material to at least portions of the first and second surfaces; mateably inserting an electrode into each indentation; abutting an electrode of opposing polarity on the second surface opposite the first electrode; applying high voltage direct current electrical power through the electrodes and piezoelectric material for a predetermined duration; cutting the piezoelectric material to remove any indentations and to prepare a generally planar two-sided disk; and installing the disk within a transducer probe.
Claim 2
Independent Claim
119 words
A method for nonuniform poling of a piezoelectric transducer comprising: altering a flat first surface of a piezoelectric material to produce at least one indentation; cutting the piezoelectric material to present a opposite second surface generally parallel with the first surface; bonding a highly electrically conductive material to at least portions of the first and second surfaces; mateably inserting an electrode into each indentation; abutting an electrode of opposing polarity on the second surface opposite the first electrode; applying high voltage direct current electrical power through the electrodes and piezoelectric material for a predetermined duration; cutting the piezoelectric material to remove any indentations and to prepare a generally planar two-sided disk; and installing the disk within a transducer probe.
Claim 3
Dependent Claim
10 words
A method of claim 1 wherein the indentation is hemispherical.
Claim 4
Dependent Claim
14 words
The method of claim 2 wherein the electrode inserted in the indentation is spherical.
Claim 5
Dependent Claim
27 words
The method of claim 3 wherein the electrode of opposing polarity includes an indentation to mateably received a portion of the piezoelectric material including the second surface.
Claim 6
Dependent Claim
15 words
The method of claim 1 wherein the highly electrically conductive material is a metal film.
Claim 7
Dependent Claim
17 words
The method of claim 5 wherein the metal film is deposited onto the first and second surfaces.
Claim 8
Dependent Claim
22 words
The method of claim 6 wherein the metal film is comprised of a chromium base layer covered by a gold top layer.
Claim 9
Dependent Claim
17 words
The method of claim 1 wherein the first surface is altered to produce two or more indentations.
Claim 10
Dependent Claim
31 words
The method of claim 8 wherein conductive material is bonded only to the indentations on the first surface, and only to corresponding separated and electrically insulated positions on the second surface.
Claim 11
Dependent Claim
35 words
The method of claim 9 wherein the first and second sets of electrodes are positionable to the different portions of coatings on opposite surfaces, each directly opposite a pair of electrodes being of opposite polarity.
Claim 12
Independent Claim
123 words
A method for producing a nonuniformly poled piezoelectric transducer element comprising: determining a desired beam response pattern for the element; quantifying the pattern by a mathematical function; sculpting a planar end of piezoelectric material in a manner correlated to the mathematical function; coding the sculpted surfaces on the planar end of the piezoelectric material; coding an opposite planar surface of the piezoelectric material on portions corresponding to sculpted portions on the planar end of the piezoelectric material; sandwiching the piezoelectric material between electrodes of preselected polarity; supplying electrical power to the electrodes for a preselected duration; removing the sculpted portions to leave a two sided planar piezoelectric element; and completely covering both sides of the planar element with a coating of conducting material.
Claim 13
Independent Claim
123 words
A method for producing a nonuniformly poled piezoelectric transducer element comprising: determining a desired beam response pattern for the element; quantifying the pattern by a mathematical function; sculpting a planar end of piezoelectric material in a manner correlated to the mathematical function; coding the sculpted surfaces on the planar end of the piezoelectric material; coding an opposite planar surface of the piezoelectric material on portions corresponding to sculpted portions on the planar end of the piezoelectric material; sandwiching the piezoelectric material between electrodes of preselected polarity; supplying electrical power to the electrodes for a preselected duration; removing the sculpted portions to leave a two sided planar piezoelectric element; and completely covering both sides of the planar element with a coating of conducting material.
Claim 14
Dependent Claim
13 words
The method of claim 11 wherein the mathematical function is a Gaussian function.
Claim 15
Dependent Claim
13 words
The method of claim 11 wherein the mathematical function is a Bessel function.
Claim 16
Dependent Claim
21 words
The method of claim 12 wherein the hemispherical centrally located cavity is sculpted in the planar end of the piezoelectric material.
Claim 17
Dependent Claim
17 words
The method of claim 14 wherein a spherical shaped electrode is mateably insertable into the hemispherical cavity.
Claim 18
Dependent Claim
28 words
The method of claim 12 wherein the electrode opposite the planar end includes a recessed cavity for mating insertion of the piezoelectric piece, including the opposite planar surface.
Claim 19
Dependent Claim
13 words
The method of claim 11 wherein the mathematical function is a Bessel function.
Claim 20
Dependent Claim
24 words
The method of claim 17 wherein a center hemispherical cavity and two concentric grooves are sculpted in the planar end of the piezoelectric material.
Claim 21
Dependent Claim
29 words
The method of claim 18 wherein the conductive coating on either planar surface is bonded to the surface in portions which are isolated and electrically insulated from one another.
Claim 22
Dependent Claim
32 words
The method of claim 19 wherein sets of electrodes are correlated with the coatings on opposite planar surfaces, each set of electrodes including at least one pair of electrodes of opposite polarity.
Claim 23
Independent Claim
171 words
The method for nonuniform poling of piezoelectric transducers comprising: machining a hemispherical indentation into a planar end of a piezoelectric rod; cutting the end of the rod containing the hemispherical indentation in a plane parallel to the end surface at a distance spaced apart from the end surface to create a bottom surface; covering the hemispherical indentation and the bottom surface with conducting material; positioning a generally mateably fitting ball-shaped electrode into the plated hemispherical indentation; fitting the bottom of the piezoelectric material into a generally mating circular indentation in a second electrode; positioning the piezoelectric material and first and second electrodes within a heated medium; applying high voltage direct current electrical power of opposite polarity to the first and second electrodes for a predetermined duration; removing the piezoelectric material and electrodes from the heated medium and removing the first and second electrodes; removing the portion of the piezoelectric material containing the hemispherical indentation to produce a planar two sided disk, the disk containing nonuniform poling generally approximating a Gaussian function.
Claim 24
Independent Claim
171 words
The method for nonuniform poling of piezoelectric transducers comprising: machining a hemispherical indentation into a planar end of a piezoelectric rod; cutting the end of the rod containing the hemispherical indentation in a plane parallel to the end surface at a distance spaced apart from the end surface to create a bottom surface; covering the hemispherical indentation and the bottom surface with conducting material; positioning a generally mateably fitting ball-shaped electrode into the plated hemispherical indentation; fitting the bottom of the piezoelectric material into a generally mating circular indentation in a second electrode; positioning the piezoelectric material and first and second electrodes within a heated medium; applying high voltage direct current electrical power of opposite polarity to the first and second electrodes for a predetermined duration; removing the piezoelectric material and electrodes from the heated medium and removing the first and second electrodes; removing the portion of the piezoelectric material containing the hemispherical indentation to produce a planar two sided disk, the disk containing nonuniform poling generally approximating a Gaussian function.
Claim 25
Dependent Claim
32 words
The method of claim 21 wherein the hemispherical indentation is of a depth related to the profile of an electrical field desired to be set up in the piezoelectric rod during poling.
Claim 26
Dependent Claim
38 words
The method of claim 21 wherein the step of cutting the end of the rod is preselected so that the distance between the plane parallel to the end surface is correlated to the center frequency of the transducer.
Claim 27
Dependent Claim
12 words
The method of claim 21 wherein the heated medium is oil means.
Claim 28
Dependent Claim
23 words
The method of claim 21 wherein the diameter of the hemispherical indentation is proportional to the electrical field strength through the piezoelectric material.
Claim 29
Independent Claim
202 words
A method for nonuniform poling of a piezoelectric transducer comprising: machining the top planar surface of a piezoelectric rod to produce a center hemispherical cavity and first and second concentric grooves surrounding the cavity; depositing conducting material to the surfaces of the cavity and grooves; cutting the metal rod in a spaced apart plane from the plane defining the end surface of the rod to produce a bottom surface; depositing conducting material on the bottom surface in a pattern generally corresponding to the cavity and first and second grooves; mateably inserting a ball shaped electrode into the center cavity; mateably inserting one or more electrodes into each groove; abutting an electrode to the conductive material on the bottom surface opposite the cavity; abutting one or more electrodes to the highly conductive material on the bottom surface corresponding generally with the electrodes in the grooves; applying high voltage direct current electrical power to the electrodes so that aligned and corresponding electrodes in the cavity and grooves as compared to on the bottom surface are of opposite polarities; removing the electrodes; and cutting the piezoelectric material to remove the cavity and grooves to produce a planar two sided disk, the disk being nonuniformly poled.
Claim 30
Independent Claim
202 words
A method for nonuniform poling of a piezoelectric transducer comprising: machining the top planar surface of a piezoelectric rod to produce a center hemispherical cavity and first and second concentric grooves surrounding the cavity; depositing conducting material to the surfaces of the cavity and grooves; cutting the metal rod in a spaced apart plane from the plane defining the end surface of the rod to produce a bottom surface; depositing conducting material on the bottom surface in a pattern generally corresponding to the cavity and first and second grooves; mateably inserting a ball shaped electrode into the center cavity; mateably inserting one or more electrodes into each groove; abutting an electrode to the conductive material on the bottom surface opposite the cavity; abutting one or more electrodes to the highly conductive material on the bottom surface corresponding generally with the electrodes in the grooves; applying high voltage direct current electrical power to the electrodes so that aligned and corresponding electrodes in the cavity and grooves as compared to on the bottom surface are of opposite polarities; removing the electrodes; and cutting the piezoelectric material to remove the cavity and grooves to produce a planar two sided disk, the disk being nonuniformly poled.
Claim 31
Dependent Claim
30 words
The method of claim 26 wherein the spacing, depth, and diameter of the hemispherical cavity and first and second concentric grooves are proportional to the response pattern for the transducer.
Claim 32
Dependent Claim
14 words
The method of claim 27 wherein the response pattern generally approximates a Bessel function.
Claim 33
Dependent Claim
50 words
The method of claim 26 wherein the spacing, depth, and diameter of the central hemispherical cavity and first and second concentric grooves is proportional to the relationship between a center prominent lobe and first and second side lobes on each side of the center lobe according to a Bessel function.
Claim 34
Dependent Claim
19 words
The method of claim 26 wherein three electrodes are positionable at spaced apart positions around and in each groove.
Claim 35
Dependent Claim
23 words
The method of claim 30 wherein a plurality of electrodes are positionable at spaced apart positions corresponding to the electrodes for each groove.
Claim 36
Dependent Claim
32 words
The method of claim 31 wherein electrodes corresponding to the hemispherical cavity and second concentric groove are of like polarity, whereas electrodes corresponding to the first concentric groove is of opposite polarity.
Claim 37
Dependent Claim
28 words
The method of claim 26 comprising the first step of installing the planar two-sided disk within a transducer piston probe housing for connection to a transducer driving means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-10-08 | 1994-04-09 | 1994-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-10-08 | 1998-04-09 | 1998-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-10-08 | 2002-04-09 | 2002-10-09 | $7700.00 | Window Closed / Lapsed |