US3703652A - Electroacoustic transducer - Google Patents

Electroacoustic transducer Download PDF

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Publication number
US3703652A
US3703652A US117619A US3703652DA US3703652A US 3703652 A US3703652 A US 3703652A US 117619 A US117619 A US 117619A US 3703652D A US3703652D A US 3703652DA US 3703652 A US3703652 A US 3703652A
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US
United States
Prior art keywords
acoustical
transducer element
transducer
acoustic
oscillations
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US117619A
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English (en)
Inventor
Masahiro Noda
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Mitsubishi Electric Corp
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Mitsubishi Electric Corp
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Publication date
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H04R17/10—Resonant transducers, i.e. adapted to produce maximum output at a predetermined frequency
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/34—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means
    • H04R1/345—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means for loudspeakers

Definitions

  • the electroacoustic transducer element emits an acoustic signal, such as an ultrasonic wave, from both the inner and outer surfaces of the element by expansion and contraction oscillations caused by an electrical signal applied thereto.
  • the transducer element can generate an electrical signal by applying an acoustical oscillation thereto.
  • the inner and outer acoustical reflection plates will reflect acoustic oscillations emitted from the inner and outer surfaces in an axial direction in such a manner that a variable range of directivity may be realized and a high acoustic output obtained.
  • the acoustic reflection plates are provided at suitable inclined angles so that the phases of acoustic oscillations emitted in the radial direction from both the inner and outer surfaces of the cylindrically shaped element of the electroacoustic transducer will essentially coincide.
  • This invention relates generally to a transducer having a cylindrically shaped electroacoustic transducer element which may be expansion and contraction oscillated in the radial direction of the cylinder, and more particularly, to a transducer having two acoustic reflection plates, one being within the cylindrically shaped transducer element and the other being exterior thereto.
  • electroacoustic transducers used for ultrasonic impulse proof devices, substance movement detectors, and the like have included a cylindrically shaped electroacoustic transducer element and a single acoustical reflection plate.
  • the electroacoustic transducer element will emit an acoustic oscillation when excited by an electrical signal and will generate an electrical signal when excited by an acoustic or mechanical oscillating signal.
  • the single acoustic reflection plate was provided on either the inside or the outside of the cylindrically shaped electroacoustic transducer element.
  • the acoustic oscillations emitted from the inner surface of the cylindrically shaped electroaeoustic transducer element would be of an opposite phase to that of the acoustic oscillations emitted from the outer surface of the cylindrically shaped element.
  • the acoustic oscillations emitted in the radial direction from either the inner surface of the cylinder or the outer surface of the cylinder would be reflected in the axial direction of the cylinder and the remaining portion of acoustical oscillations would be shielded with an acoustic shielding plate.
  • One other object of the present invention is to provide a new and improved unique electroacoustical transducer wherein the acoustical oscillations emitted from both the inner and outer surfaces of the cylindrically shaped element thereof can be effectively utilized.
  • an electroacoustical transducer which utilizes a pair of acoustical reflection plates one mounted within a cylindrically shaped transducer element and the other mounted exterior thereto such that the acoustic oscillations emitted from both the inner and outer surfaces of the cylindrically shaped transducer element will be axially directed when the element is expansion and contraction oscillated by an electrical signal.
  • the inner acoustical reflection plate is of a conical shape and the outer acoustical reflection plate is a conical cylinder having a notched portion on the upper edge thereof.
  • angles of the two reflection plates are appropriately determined so as to increase the power of acoustical oscillation and to provide a variable sharp to broad range of directivity. Additionally, it is possible to select a sectional shape of directivity by shielding a part of an acoustical reflection plate with an acoustical shielding plate.
  • FIG. 1 is a view of a cylindrically shaped electroaeoustical transducer element showing the various modes of oscillation thereof;
  • FIG. 2 shows a plane view and a longitudinal sectional view of a conventional prior art transducer having a cylindrically shaped electroacoustical transducer element and a single acoustical reflection plate therein,
  • FIG. 3 shows a plane view and a longitudinal sectional view of another conventional prior art transducer having a cylindrically shaped electroacoustical transducer element and an acoustical reflection plate therein;
  • FIG. 4 shows a plane view and a sectional side view of one preferred embodiment of an electroacoustical transducer in accordance with the present invention.
  • FIG. 5 shows a plane view, a longitudinal sectional view taken along the line bb of the plane view, and a longitudinal section view taken along the line c--c of the plane view of an electroacoustical transducer in accordance with the present invention.
  • FIG. 1 wherein the modes of mechanical oscillation of a cylindrically shaped electroacoustical transducer element of the present invention is shown and may be made of a porcelain of barium titanate, lead zirco-titanate, or the like.
  • the electroaeoustical transducer element 1 may be expansion oscillated in the direction shown by the arrows 2 and may be contraction oscillated in the direction shown by the arrows 3.
  • cylindrically shaped electroacoustic transducer element 1 will emit acoustic oscillations by causing expansion and contraction oscillations when excited with an electrical signal supplied by a proper source, and on the other hand will generate an electrical signal when acoustically or mechanically oscillated from a proper source.
  • a conventional prior art transducer is shown in a plane view (A) and in a longitudinal sectional view (B).
  • the transducer includes the cylindrically shaped electroacoustic transducer element 1, an acoustic shielding plate 4, and a conical acoustical reflection plate mounted within the transducer element 1.
  • the acoustical reflecting plate 5 is shown as having an angle dz, for reflecting acoustic oscillations.
  • the symbol P shows the direction of transmission of the reflecting acoustic oscillations.
  • FIG. 3 another conventional prior art transducer is shown in a plane view (A) and in a longitudinal sectional view (B).
  • the transducer again includes the cylindrically shaped electroacoustic transducer element 1, and an acoustical shielding plate 6.
  • an acoustical reflection plate 7 is herein provided and the same is mounted exterior to the transducer element 1 and has an angle d), for reflecting acoustical oscillations therefrom.
  • the reflection plates 5 and 7 may be made of any material having an acoustical impedance such as a metal, for example, of copper, aluminum or the like, or a plastic or the like.
  • either the acoustical oscillations emitted from the inner surface or the outer surface of the cylinder 1 in the radial direction will be reflected to the axial direction of the cylinder 1 by utilizing the acoustic reflection plate 5 or 7, while the remaining acoustic oscillations will be shielded by using either the acoustic shielding plate 4 or 6.
  • the conventional transducers as described above with reference FIGS. 2 and 3, only include a single reflection means and thereby may effectively utilize the acoustic oscillations emitted from either the inner surface or the outer surface of the cylindrically shaped transducer element, but not both, the efficiency thereof will be extremely low and thereby may not be effectively utilized.
  • the range of directivity in the axial direction of the cylinder is extremely narrow for changes in either of the angles 4), or (b, of the acoustical reflection plates.
  • FIG. 4 one preferred embodiment of the present invention for overcoming the above described disadvantages of the prior art is illustrated in a plane view (A) and in a longitudinal sectional view (B).
  • the electroacoustic transducer of FIG. 4 includes a pair of reflection plates 5 and 7, the first plate 5 being mounted within the cylindrically shaped electroacoustic transducer element 1 and the second plate 7 being mounted exterior thereto.
  • the inner acoustical reflection plate 5 has an angle of a, of reflection and the acoustical reflection plate 7 has an angle of o of reflection and the same again may be made of a metal, plastic, or the like.
  • the acoustical reflection plate 5 may be formed in a conical shape, but it should be understood that the same is not so limited and that, for example, the inclined straight lines of the reflection plate 5 may be of a rounded nature.
  • the outside or exterior acoustical reflection plate 7 may be formed of a conical cylindrical shape and again, the inclined straight line portions thereof may be rounded.
  • the cylindrically shaped electroacoustic transducer element 1 may be oscillated by an electrical signal provided from a conventional source such that acoustic oscillations are emitted from both the inner and outer surfaces of the element 1. Again, the phase of the acoustic oscillations emitted from the inner and outer surfaces are initially opposite each other.
  • the angle d5, of the inner acoustical reflec tion plate can be adjusted with the angle (1!): of the outer acoustical reflection plate so that a differential is provided between the transmission path of the acoustical oscillations emitted from the inner surface of the cylinder and the transmission path of the acoustical oscillations emitted from the outer surface of the cylinder such that the phase of all of the acoustical oscillations emitted from the transducer will substantially coincide with each other in the axial direction of the cylinder.
  • the magnitude of the usable acoustical oscillations is greatly increased and likewise the efficiency of the electroacoustic transducer.
  • the directivity of the transducer can be varied over a wide range by properly selecting the angle d2, of the inner acoustical reflection plate and the angle d), of the outer acoustical reflection plate.
  • the directivity was 10 of half value angle, when the electroacoustic transducer element 1 had an outer diameter of 25 mm., an inner diameter of 21 mm., and a height of IO mm.
  • the electroacoustic transducer element 1 was excited by a 40 kHz. electrical signal and the angle of the inner acoustical reflection plate 5 was and the angle d), of the outer acoustical reflection plate 7 was 50.
  • the directivity was also 10 of the half value angle when the electroacoustical transducer element 1 had an outer diameter of 38 mm., an inner diameter of 34 mm., and a height of 10 mm.
  • an electrical signal of 40 kHz. was applied to the electroacoustical transducer element 1; however, here the angle a, of the inner acoustical reflection plate 5 was set to and the angle d, of the outer acoustical reflection plate 7 was set to 45. Under the same conditions, when the angle d1, of the outer acoustical reflection plate 7 was set to a directivity of 10 of the half value angle was obtained.
  • FIG. 5 another preferred and alternative embodiment of the present invention is shown in a plane view (A), in a sectional view (B), taken along the line b-b of the plane view, and in a sectional view (C) taken along the line c-c of the plane view.
  • the outer acoustical reflection plate 7 is beveled and the acoustical shielding plate 8 is placed on top of the beveled portion as shown in FIG. 5(A).
  • acoustic or electrical oscillations emitted from both the inner and outer surfaces of the cylindrically shaped electroacoustical transducer element thereof which are of opposite phase to each other can, by the provision of a pair of reflection plates, be changed in the axial direction such that the phases of the acoustic or electrical oscillations are made to coincide, whereby the power of usable acoustical or electrical oscillation is greatly increased.
  • the directivity of the acoustic or electrical oscillations can be readily changed by properly selecting the angles of both of the acoustical reflection plates thereof.
  • the transducer of the present invention can be utilized for receiving, as well as transmitting acoustical signals.
  • the present invention has been described as emitting an acoustical signal of the ultrasonic type, the invention is not so limited and may be equally used for transmitting acoustical sounds in other ranges, such, for example, as in the audible range. It is therefore to be understood that within the scope of the appended Claims, the invention may be practiced otherwise than as specifically described herein.
  • An electroacoustical transducer comprising:
  • a second acoustical reflection plate having an acoustical impedance which is the same as said given acoustical impedance, said second acoustical reflection plate mounted in said electroacoustical transducer abutting an exterior surface of said transducer element for changing the direction of transmission of acoustical oscillations therefrom, said first and second reflection plates having different respective reflecting angles relative to said electroacoustical transducer element for producing different length transmission paths between said transducer element and said first and second reflection plates so that the phases of all of the acoustical oscillations reflected from said first and second reflection plates will substantially coincide with each other in the axial direction of the cylindrically shaped electroacoustical transducer element.
  • a transducer according to claim 1, wherein said second acoustical reflection plate is a conical shape and is beveled at the upper edge thereof.
  • a transducer according to claim I wherein a shielding plate is mounted to said transducer for shielding a part of said transducer to control the acoustical directivity thereof.

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  • Health & Medical Sciences (AREA)
  • Otolaryngology (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Piezo-Electric Transducers For Audible Bands (AREA)
US117619A 1970-02-25 1971-02-22 Electroacoustic transducer Expired - Lifetime US3703652A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP1608270 1970-02-25

Publications (1)

Publication Number Publication Date
US3703652A true US3703652A (en) 1972-11-21

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Family Applications (1)

Application Number Title Priority Date Filing Date
US117619A Expired - Lifetime US3703652A (en) 1970-02-25 1971-02-22 Electroacoustic transducer

Country Status (4)

Country Link
US (1) US3703652A (enExample)
DE (1) DE2109013C3 (enExample)
FR (1) FR2161734B1 (enExample)
GB (1) GB1331841A (enExample)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3982142A (en) * 1973-11-05 1976-09-21 Sontrix, Inc. Piezoelectric transducer assembly and method for generating a cone shaped radiation pattern
US4142412A (en) * 1976-05-12 1979-03-06 Sutures Inc. Doppler flow meter and method
US4259870A (en) * 1979-02-26 1981-04-07 Howmedica Inc. Doppler method of measuring flow
US4439847A (en) * 1981-12-21 1984-03-27 The Stoneleigh Trust High efficiency broadband directional sonar transducer
US4582065A (en) * 1984-06-28 1986-04-15 Picker International, Inc. Ultrasonic step scanning utilizing unequally spaced curvilinear transducer array
US4630342A (en) * 1984-12-21 1986-12-23 Motorola, Inc. Method of mounting a piezoelectric helmholtz transducer on a printed circuit board
US5212671A (en) * 1989-06-22 1993-05-18 Terumo Kabushiki Kaisha Ultrasonic probe having backing material layer of uneven thickness
US20160060302A1 (en) * 2013-04-03 2016-03-03 Tulane University Expression of HIV inhibitors by Mesenchymal stem cells
US20170323626A1 (en) * 2013-06-27 2017-11-09 Areva Np Ultrasound transducer

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2005741A (en) * 1932-12-15 1935-06-25 Harvey C Hayes Magneto-strictive sound generator
US2855526A (en) * 1955-10-24 1958-10-07 Aeroprojects Inc Apparatus for generating ultrasonic energy of high intensity
US3271596A (en) * 1963-11-12 1966-09-06 Boeing Co Electromechanical transducers
US3302163A (en) * 1965-08-31 1967-01-31 Jr Daniel E Andrews Broad band acoustic transducer
US3325779A (en) * 1965-09-13 1967-06-13 Westinghouse Electric Corp Transducer

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2005741A (en) * 1932-12-15 1935-06-25 Harvey C Hayes Magneto-strictive sound generator
US2855526A (en) * 1955-10-24 1958-10-07 Aeroprojects Inc Apparatus for generating ultrasonic energy of high intensity
US3271596A (en) * 1963-11-12 1966-09-06 Boeing Co Electromechanical transducers
US3302163A (en) * 1965-08-31 1967-01-31 Jr Daniel E Andrews Broad band acoustic transducer
US3325779A (en) * 1965-09-13 1967-06-13 Westinghouse Electric Corp Transducer

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3982142A (en) * 1973-11-05 1976-09-21 Sontrix, Inc. Piezoelectric transducer assembly and method for generating a cone shaped radiation pattern
US4142412A (en) * 1976-05-12 1979-03-06 Sutures Inc. Doppler flow meter and method
US4259870A (en) * 1979-02-26 1981-04-07 Howmedica Inc. Doppler method of measuring flow
US4439847A (en) * 1981-12-21 1984-03-27 The Stoneleigh Trust High efficiency broadband directional sonar transducer
US4582065A (en) * 1984-06-28 1986-04-15 Picker International, Inc. Ultrasonic step scanning utilizing unequally spaced curvilinear transducer array
US4630342A (en) * 1984-12-21 1986-12-23 Motorola, Inc. Method of mounting a piezoelectric helmholtz transducer on a printed circuit board
US5212671A (en) * 1989-06-22 1993-05-18 Terumo Kabushiki Kaisha Ultrasonic probe having backing material layer of uneven thickness
US20160060302A1 (en) * 2013-04-03 2016-03-03 Tulane University Expression of HIV inhibitors by Mesenchymal stem cells
US20170323626A1 (en) * 2013-06-27 2017-11-09 Areva Np Ultrasound transducer
US10242656B2 (en) * 2013-06-27 2019-03-26 Areva Np Ultrasound transducer

Also Published As

Publication number Publication date
DE2109013C3 (de) 1975-08-21
FR2161734A1 (enExample) 1973-07-13
DE2109013B2 (de) 1975-01-09
GB1331841A (en) 1973-09-26
FR2161734B1 (enExample) 1976-07-09
DE2109013A1 (de) 1971-09-16

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