Ultrasonic transducer having impedance matching layer
First Claim
1. A resonant type transducer comprising:
- a vibrator body comprising piezoelectric or electrostrictive material having a first acoustic impedance associated with a resonant frequency;
a matching layer coupled to said vibrator body and having a second acoustic impedance;
said matching layer acoustically matching said piezoelectric or electrostrictive vibrator to a radiation medium contacting said matching layer, said radiation medium having a third acoustic impedance;
wherein said second acoustic impedance associated with said matching layer is less than said third acoustic impedance associated with said radiation medium and greater than said first impedance associated with said resonance frequency of said vibrator body.
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Abstract
A resonant-type transducer providing a narrow band, high output or high sensitivity signal to a radiation medium, the resonant transducer comprising a vibrator body comprising piezoelectric or electrorestricitive material having a first acoustic impedance at a resonant condition, and a matching layer for acoustically matching the piezoelectric vibrator body at resonance to the radiation medium. Another type of a matching layer structure comprising a first layer of material of a first thickness t1 and acoustic impedance Z1 and having an inner surface coupled to a front surface of the vibrator body, and a second layer of material of thickness t2 and acoustic impedance Z2 and having an outer surface coupled to the radiation medium wherein the second layer has a high acoustic impedance relative to the first layer and wherein the second layer has a thickness of less than one quarter wavelength of the resonant frequency so as to cause a reflection from the high impedance layer to provide a combined impedance of the matching layer at the front surface of the vibrator body which is less than the acoustic impedance of the radiation medium. These matching layer structures provide increased output power and also higher receiving sensitivity for resonant type transducers.
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Citations
32 Claims
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1. A resonant type transducer comprising:
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a vibrator body comprising piezoelectric or electrostrictive material having a first acoustic impedance associated with a resonant frequency;
a matching layer coupled to said vibrator body and having a second acoustic impedance;
said matching layer acoustically matching said piezoelectric or electrostrictive vibrator to a radiation medium contacting said matching layer, said radiation medium having a third acoustic impedance;
wherein said second acoustic impedance associated with said matching layer is less than said third acoustic impedance associated with said radiation medium and greater than said first impedance associated with said resonance frequency of said vibrator body. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A resonant type tranducer providing a narrowband, high output or high sensitvity signal to a radiation medium, said resonant transducer comprising:
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a vibrator body comprising piezoelectric or electrostrictive material having a first acoustic impedance associated with a resonant frequency; and
a matching layer for acoustically matching said vibrator body at resonance to said radiation medium, said matching layer comprising;
a first layer of material of thickness t1 and acoustic impedance Z1 and having an inner surface coupled to a front surface of said vibrator body; and
a second layer of material of thickness t2 and acoustic impedance Z2 and having an outer surface coupled to said radiation medium, wherein the acoustic impedance Z2 is greater than the first acoustic impedance Z1 so as to provide a combined impedance of the matching layer at the front surface of the vibrator body which is less than the acoustic impedance of the radiation medium. - View Dependent Claims (19, 20, 21, 22, 23)
said first layer comprises a material selected from the group consisting of;
polyurethane, polybutadiene, polyisoprene, polychloroprene, silicon rubber, and soft polyethylene; and
,said second layer comprises a material selected from the group consisting of;
mylar, polyester, polystyrene, polyimide, polyethersulfer, metal and glass.
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24. A method of forming a resonance transducer, said method comprising:
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providing a piezoelectric body having a first acoustic impedance indicative of material characteristics of said piezoelectric body;
providing a propagation medium having a second acoustic impedance; and
coupling a matching layer between said piezoelectric body and said propagation medium, wherein said piezoelectric body vibrating at the resonance frequency has a resonance impedance less than said second acoustic impedance associated with said propagation medium, and wherein said matching layer has a third acoustic impedance less than said second acoustic impedance associated with said propagation medium for providing a high output or high sensitivity signal to said medium when operated at the resonance frequency.- View Dependent Claims (25)
a vibrator body comprising piezoelectric or electrostrictive material having a first acoustic impedance associated with a resonant frequency; a matching layer coupled to said vibrator body and having a second acoustic impedance;
said matching layer acoustically matching said piezoelectric or electrostrictive vibrator to a radiation medium contacting said matching layer, said radiation medium having a third acoustic impedance, wherein said second acoustic impedance associated with said matching layer is less than said third acoustic impedance associated with said radiation medium and greater than said first ipdance associated with said resonance frequency of said vibrator body.
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26. A resonant type transducer for producing and/or detecting ultrasound energy in an adjacent radiation medium, said radiation medium having an acoustic impedance associated therewith, said transducer comprising:
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a vibrator body comprising piezoelectric or electrostrictive material and having a first impedance associated with a resonance frequency that is less than that of said acoustic impedance of said radiation medium, said vibrator body having a front surface and a rear surface;
a backing layer disposed at said rear surface of said vibrator body for absorbing ultrasound energy from the vibrator body; and
a matching layer having a first surface coupled to said front surface of said vibrator body and a second surface coupled to said radiation medium for communicating ultrasound energy therebetween, wherein said matching layer has an acoustic impedance less than the acoustic impedance of the radiation medium and greater than sad first impedance at said resonance frequency of said vibrator body. - View Dependent Claims (27)
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28. A resonant type transducer for producing and/or detecting ultrasound energy in an adjacent radiation medium, said radiation medium having an acoustic impedance associated therewith, said transducer comprising:
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a vibrator body comprising piezoelectric or electrostrictive material and having a first impedance associated with a resonance frequency that is less than that of said acoustic impedance of said radiation medium said vibrator body having a front surface through which ultrasound energy is transferred to said radiation medium;
a backing layer disposed at said rear surface of said vibrator body for absorbing ultrasound energy from the vibrator body; and
a matching layer for acoustically matching said vibrator body at said resonance frequency to said radiation medium said matching layer comprising;
a first layer of material of thickness t1 and acoustic impedance Z1, said first layer having a first surface coupled to said front surface of said vibrator body, and a second surface;
a second layer of material of thickness t2 and acoustic impedance Z2 greater than Z1, said second layer having a first surface coupled to said second surface of said fis layer, and a second surface coupled to said radiation medium, wherein said first and second layers are adapted to provide an effective impedance of the matching layer at the front surface of said vibrator body that is less than the acoustic impedance of the radiation medium and greater that of said vibrator body impedance at said resonance frequency. - View Dependent Claims (29, 30, 31, 32)
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Specification