US5438554A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Tunable acoustic resonator for clinical ultrasonic transducers
Assignee: HP Inc
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Filing: 1994-02-28
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Granted: 1995-08-01
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Expires: 2014-02-28
Abstract
Abstract A tunable ultrasonic probe includes a body of a first piezoelectric material acoustically coupled in series with a body of a second piezoelectric material. The second piezoelectric material has a Curie temperature that is substantially different than that of the first piezoelectric material. Preferably, the first piezoelectric material is a conventional piezoelectric ceramic, such as lead zirconate titanate, while the second piezoelectric material is a relaxor ferroelectric ceramic, such as lead magnesium niobate. At an operating temperature of the probe, the first piezoelectric material has a fixed polarization. In contrast, the second piezoelectric material has a polarization that is variable relative to the fixed polarization of the first piezoelectric material. A preferred novel arrangement of electrodes electrically couples the bodies in parallel with one another. An oscillating voltage for exciting the acoustic signals in the probe is coupled with the electrodes. The polarization of the second piezoelectric material is variably controlled by a bias voltage coupled with the electrodes. In a preferred embodiment, the bias voltage has a reversible electrical polarity for selecting one resonant frequency from a plurality of resonant frequencies of the probe. In another preferred embodiment, the bias voltage source has a variable voltage level for selecting at least one of a plurality of resonant frequencies of the probe.
Inventors
- 👤 Mir S. Seyed-Bolorforosh
- 👤 Michael Greenstein
- 👤 Turuvekere R. Gururaja
- 👤 Henry Yoshida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 02:21
CPC Classifications
G; G10; G10K; G10K11/00; G10K11/02; B; B06; B06B; B06B1/00; B06B1/02; B06B1/06; B06B1/0607; B06B1/0622
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
147 words
A tunable ultrasonic probe for coupling acoustic signals between the probe and a medium having an acoustic impedance, comprising: a body of a first piezoelectric ceramic material having a Curie temperature; a body of a second piezoelectric material acoustically coupled in series with the body of the first piezoelectric material, body of the second piezoelectric material having a polarization and further having a Curie temperature that is substantially different than that of the first piezoelectric material; an electrode means for electrically coupling the bodies in parallel with one another and for applying a voltage potential to each of the bodies; an oscillating voltage means for exciting the acoustic signals in the probe, the oscillating voltage means being coupled with the electrode means; and a bias voltage means for variably controlling the polarization of the second piezoelectric material, the bias voltage means being coupled with the electrode means.
Claim 2
Dependent Claim
147 words
A tunable ultrasonic probe for coupling acoustic signals between the probe and a medium having an acoustic impedance, comprising: a body of a first piezoelectric ceramic material having a Curie temperature; a body of a second piezoelectric material acoustically coupled in series with the body of the first piezoelectric material, body of the second piezoelectric material having a polarization and further having a Curie temperature that is substantially different than that of the first piezoelectric material; an electrode means for electrically coupling the bodies in parallel with one another and for applying a voltage potential to each of the bodies; an oscillating voltage means for exciting the acoustic signals in the probe, the oscillating voltage means being coupled with the electrode means; and a bias voltage means for variably controlling the polarization of the second piezoelectric material, the bias voltage means being coupled with the electrode means.
Claim 3
Dependent Claim
46 words
A probe as in claim 1 wherein: the body of the first piezoelectric material has a polarization that is fixed; and the polarization of the body of the second piezoelectric material is variable relative to the fixed polarization of the body of the first piezoelectric material.
Claim 4
Dependent Claim
40 words
A probe as in claim 1 wherein the bias voltage means for variably controlling the polarization of the second piezoelectric material includes a reversible polarity means for selecting one resonant frequency from a plurality of resonant frequencies of the probe.
Claim 5
Dependent Claim
41 words
A probe as in claim 1 wherein the bias voltage means for variably controlling the polarization of the second piezoelectric material includes a variable voltage level means for selecting at least one of a plurality of resonant frequencies of the probe.
Claim 6
Dependent Claim
77 words
A probe as in claim 1 wherein: the body of the first piezoelectric ceramic material comprises a piezoelectric ceramic layer portion contiguous with a bulk remainder portion of the first piezoelectric ceramic material, the layer and the remainder each having a respective acoustic impedance; and the probe further comprises a means for controlling the acoustic impedance of the layer so as to substantially match the acoustic impedance of the remainder with the acoustic impedance of the medium.
Claim 7
Dependent Claim
23 words
A probe as in claim 5 wherein the means for controlling the acoustic impedance of the layer comprises grooves extending through the layer.
Claim 8
Dependent Claim
20 words
A probe as in claim 6 wherein the electrode means includes an electrode layer extending into and contacting the grooves.
Claim 9
Dependent Claim
85 words
A probe as in claim 1 wherein: the body of the first piezoelectric ceramic material comprises a piezoelectric ceramic layer portion contiguous with a bulk remainder portion of piezoelectric ceramic material, the layer and the remainder each having a respective acoustic impedance; and the probe further comprises a means for controlling the acoustic impedance of the layer at a plurality of tunable resonant frequencies of the probe so as to substantially match the acoustic impedance of the remainder with the acoustic impedance of the medium.
Claim 10
Dependent Claim
25 words
A probe as in claim 1 wherein the Curie temperature of the second piezoelectric material is substantially lower than that of the first piezoelectric material.
Claim 11
Dependent Claim
21 words
A probe as in claim 9 wherein the Curie temperature of the second piezoelectric material is below approximately sixty degrees celsius.
Claim 12
Dependent Claim
30 words
A probe as in claim 9 wherein the Curie temperature of the second piezoelectric material is within a range from approximately twenty five degrees celsius to approximately forty degrees celsius.
Claim 13
Dependent Claim
35 words
A probe as in claim 1 wherein: the first piezoelectric material has a dielectric constant; and the second piezoelectric material has a dielectric constant that is substantially higher than that of the first piezoelectric material.
Claim 14
Dependent Claim
105 words
A probe as in claim 1 wherein: the body of the first piezoelectric material has a first face and an opposing face; the body of the second piezoelectric material has a first face and an opposing face; the electrode means includes a first electrode layer contacting the first face of the body of the first piezoelectric material and contacting the first face of the body of the second piezoelectric material; and the electrode means further includes a second electrode layer sandwiched between the opposing face of the body of the first piezoelectric material and the opposing face of the body of the second piezoelectric material.
Claim 15
Dependent Claim
73 words
A probe as in claim 13 wherein: the oscillating voltage means has a first electrical lead coupled to the first electrode layer and has a second electrical lead capacitively coupled to the second electrode layer; and the bias voltage means for variably controlling the polarization of the second piezoelectric material has a first electrical lead coupled with the first electrode layer and has a second electrical lead coupled with the second electrode layer.
Claim 16
Dependent Claim
54 words
A probe as in claim 1 wherein: the body of the first piezoelectric material has a thickness dimension; the body of the second piezoelectric material has a thickness dimension; and the thickness dimension of the body of the second piezoelectric material is substantially different from that of the body of the first piezoelectric material.
Claim 17
Dependent Claim
32 words
A probe as in claim 15 wherein the probe further comprises a plurality of bodies of the first piezoelectric material acoustically coupled in series with the body of the second piezoelectric material.
Claim 18
Dependent Claim
57 words
A probe as in claim 16 wherein: the bodies of the first piezoelectric material each have a respective capacitance; the body of the second piezoelectric material has a capacitance; and the capacitance of the body of the second piezoelectric material is approximately equal to a sum of the respective capacitances of bodies of the first piezoelectric material.
Claim 19
Dependent Claim
67 words
A probe as in claim 1 wherein: the first piezoelectric material is characterized by a first acoustic velocity of the acoustic signals as they propagate through the first piezoelectric material; the second piezoelectric material is characterized by a second acoustic velocity of the acoustic signals as they propagate through the second piezoelectric material; and the second acoustic velocity is approximately the same as the first acoustic velocity.
Claim 20
Dependent Claim
43 words
A probe as in claim 1 further comprising a damping support body acoustically coupled in series with the body of the second piezoelectric material for damping unwanted acoustic signals and for drawing unwanted heat away from the body of the second piezoelectric material.
Claim 21
Dependent Claim
119 words
A tunable ultrasonic probe comprising: a body of a first piezoelectric material having a fixed polarization; a body of a second piezoelectric material acoustically coupled in series with the body of the first piezoelectric material, the second piezoelectric material having a polarization that is variable relative to the fixed polarization of the body of the first piezoelectric material; an electrode means for electrically coupling the bodies in parallel with one another and for applying a voltage potential to each of the bodies; an oscillating voltage means for exciting the acoustic signals in the probe, the oscillating voltage means being coupled with the electrode means; and a bias voltage means for controlling the variable polarization of the second piezoelectric material.
Claim 22
Dependent Claim
119 words
A tunable ultrasonic probe comprising: a body of a first piezoelectric material having a fixed polarization; a body of a second piezoelectric material acoustically coupled in series with the body of the first piezoelectric material, the second piezoelectric material having a polarization that is variable relative to the fixed polarization of the body of the first piezoelectric material; an electrode means for electrically coupling the bodies in parallel with one another and for applying a voltage potential to each of the bodies; an oscillating voltage means for exciting the acoustic signals in the probe, the oscillating voltage means being coupled with the electrode means; and a bias voltage means for controlling the variable polarization of the second piezoelectric material.
References Cited (Backward Citations)
US2589403A
Cited
US3093760A
Cited
US3378704A
Cited
US3462746A
Cited
US3590287A
Cited
US3401377A
Cited
US3718898A
Cited
US3833825A
Cited
US4087716A
Cited
US4096756A
Cited
US4211948A
Cited
US4356422A
Cited
GB2059716B
Cited
US4367426A
Cited
US4366406A
Cited
JPS60208200A
Cited
DE3430161A1
Cited
US4695988A
Cited
US4672591A
Cited
US4736631A
Cited
US4717851A
Cited
US4835747A
Cited
US4939826A
Cited
US5142187A
Cited
US5045746A
Cited
US5115809A
Cited
US5025790A
Cited
EP0401027A2
Cited
US5099459A
Cited
US5175709A
Cited
US5237542A
Cited
US5345139A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-07-31 | 1999-01-30 | 1999-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-07-31 | 2003-01-30 | 2003-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-07-31 | 2007-01-30 | 2007-08-01 | $7700.00 | Window Closed / Lapsed |