Tunable acoustic resonator for clinical ultrasonic transducers
First Claim
1. 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.
1 Assignment
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Accused Products
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.
167 Citations
20 Claims
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1. A tunable ultrasonic probe for coupling acoustic signals between the probe and a medium having an acoustic impedance, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A tunable ultrasonic probe comprising:
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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.
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Specification