Elevation aperture control of an ultrasonic transducer
First Claim
1. A device for transmitting and receiving acoustic waves comprising:
- a relaxor ferroelectric transducer for converting between electric wave energy and acoustic wave energy, said relaxor ferroelectric transducer having opposed generally planar sides;
first electrode means for applying an electrical signal across said relaxor ferroelectric transducer, said first electrode means being in electrical communication with said relaxor ferroelectric transducer along a first of said opposed planar sides; and
dielectric means extending between said relaxor ferroelectric transducer and said first electrode means for locally varying alignment of dipoles of said relaxor ferroelectric transducer, said dielectric means having a varying thickness, wherein said electrical communication of said first electrode means with said relaxor ferroelectric transducer changes in correspondence with said thickness.
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Accused Products
Abstract
An ultrasonic transducer for controlling an elevation aperture utilizes the electric field-induced polarization properties of relaxor ferroelectric materials. The Curie temperature of the material is typically close to room temperature, so that the application of a bias voltage provides piezoelectric activity. By varying the thickness of a dielectric layer that spaces apart the relaxor ferroelectric material from an electrode or providing the bias voltage, the piezoelectric activity can be tailored. That is, degrees of polarization of the relaxor ferroelectric material are varied spatially in correspondence with changes in thickness of the dielectric layer. The effective elevation aperture of the transducer can be varied by adjusting the bias voltage.
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Citations
20 Claims
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1. A device for transmitting and receiving acoustic waves comprising:
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a relaxor ferroelectric transducer for converting between electric wave energy and acoustic wave energy, said relaxor ferroelectric transducer having opposed generally planar sides; first electrode means for applying an electrical signal across said relaxor ferroelectric transducer, said first electrode means being in electrical communication with said relaxor ferroelectric transducer along a first of said opposed planar sides; and dielectric means extending between said relaxor ferroelectric transducer and said first electrode means for locally varying alignment of dipoles of said relaxor ferroelectric transducer, said dielectric means having a varying thickness, wherein said electrical communication of said first electrode means with said relaxor ferroelectric transducer changes in correspondence with said thickness. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A device for transmitting and receiving acoustic waves comprising:
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a transducer having a relaxor ferroelectric ceramic layer, said transducer having a first major side and an opposed second major side; a dielectric layer on said first major side, said dielectric layer increasing in thickness with departure from a central region of said first major side; a first electrode layer formed on said first major side at a side of said dielectric opposite to said transducer; a second electrode layer formed on said second major side; a first source of an excitation signal connected to one of said first and second electrode layers; and a second source of a biasing voltage connected to one of said first and second electrode layers, wherein degrees of polarization of said relaxor ferroelectric ceramic layer are varied spatially in correspondence to said changes in thickness of said dielectric layer and wherein said transducer has an effective elevation aperture that varies in response to changes in said biasing voltage from said second source. - View Dependent Claims (12, 13, 14, 15, 16)
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17. A method of controlling an elevation aperture of a transducing device comprising:
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providing a relaxor ferroelectric transducer having a dielectric layer that varies in thickness, said dielectric layer being on a first side of a transducer, said transducer having an electrode on said dielectric layer; applying a bias voltage across said transducer to align dipoles of said transducer, including providing an electrical connection to said electrode, thereby providing local variations in degrees of alignment of dipoles in correspondence with said variations in thickness of said dielectric layer; transmitting acoustic waves from said transducer into a medium of interest while applying said bias voltage, including applying an excitation signal across said transducer, said transmitting having a first penetration depth into said medium of interest; and selectively changing said bias voltage to vary said localized degrees of alignment of dipoles of said transducer, thereby changing an elevation aperture of said transducer such that the penetration depth into said medium of interest and beam characteristics of said acoustic wave transmission vary with respect to said first penetration depth. - View Dependent Claims (18, 19, 20)
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Specification