US2787777A - Ceramic transducer having stacked elements - Google Patents

Ceramic transducer having stacked elements Download PDF

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Publication number
US2787777A
US2787777A US272206A US27220652A US2787777A US 2787777 A US2787777 A US 2787777A US 272206 A US272206 A US 272206A US 27220652 A US27220652 A US 27220652A US 2787777 A US2787777 A US 2787777A
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US
United States
Prior art keywords
ceramic
elements
vibrator
transducer
discs
Prior art date
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
US272206A
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English (en)
Inventor
Leon W Camp
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bendix Aviation Corp
Original Assignee
Bendix Aviation Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority to BE509494D priority Critical patent/BE509494A/xx
Priority to BE511127D priority patent/BE511127A/xx
Priority to BE517616D priority patent/BE517616A/xx
Priority to US2733423D priority patent/US2733423A/en
Priority claimed from US228956A external-priority patent/US2774892A/en
Application filed by Bendix Aviation Corp filed Critical Bendix Aviation Corp
Priority to US272206A priority patent/US2787777A/en
Priority to GB4644/52A priority patent/GB718203A/en
Priority to GB18976/53A priority patent/GB718260A/en
Priority to FR1054912D priority patent/FR1054912A/fr
Priority to FR63717D priority patent/FR63717E/fr
Priority to GB11834/52A priority patent/GB716065A/en
Priority to GB3458/53A priority patent/GB726330A/en
Priority to FR63798D priority patent/FR63798E/fr
Publication of US2787777A publication Critical patent/US2787777A/en
Application granted granted Critical
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
    • B06B1/0611—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements in a pile
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0607—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements
    • B06B1/0622—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using multiple elements on one surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
    • B06B1/0644—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element
    • B06B1/0655—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a single piezoelectric element of cylindrical shape
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/72—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using ultrasonic, sonic or infrasonic waves
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/58—Tubes for storage of image or information pattern or for conversion of definition of television or like images, i.e. having electrical input and electrical output
    • H01J31/60—Tubes for storage of image or information pattern or for conversion of definition of television or like images, i.e. having electrical input and electrical output having means for deflecting, either selectively or sequentially, an electron ray on to separate surface elements of the screen
    • H01J31/62—Tubes for storage of image or information pattern or for conversion of definition of television or like images, i.e. having electrical input and electrical output having means for deflecting, either selectively or sequentially, an electron ray on to separate surface elements of the screen with separate reading and writing rays

Definitions

  • This invention relates to transducers for converting electrical oscillations into traveling compressional waves in fluids and vice versa, and has to do particularly with transducers for this purpose employing electro-mechanically responsive ceramics such as barium titanate.
  • These ceramics resemble piezo electric crystals in that they deform physically in response to electrical potential and vice versa, but have the great advantage over piezo electric crystals in that they are not so limited as to shape or size, are very rugged, and are relatively eflicient converters of energy from electrical to mechanical form and vice versa.
  • An object of the invention is to provide ceramic transducer designs utilizing the special properties of electromechanically responsive ceramics to high advantage in converting traveling waves in fluids to electrical oscillations and vice versa.
  • Fig. l is a longitudinal sectional view of a transducer employing a stack of ceramic disc elements
  • Fig. 2 is a side elevation view showing a variation of the structure of the ceramic element of Fig. 1;
  • Fig. 3 is a view taken in theplane III--III of Fig. 2;
  • Fig. 4 is a view similar to Fig. 2 showing a modification thereof. 7
  • the present invention is directed not to any particular ceramic composition, but to shapes and methods of mounting ceramic elements to obtain efiicient transducers.
  • Various compositons have been developed and are being developed, but for the purpose of the present invention it is merely necessary that the material be electro-mechanically responsive and be capable of being formed into the shapes disclosed.
  • Such shaping may be done by molding or extruding the material in plastic form prior to firing, or by cutting or machining after firing.
  • the material is polarized after firing by applying a high unidirectional electric field in the direction of desired polarity, which is between the working electrodes, so that the latter can be used to apply the polarizing potential.
  • Barium titanate is a common basic ingredient of presently known ceramic electro-mechanically responsive elements, and for disclosures of compositions of some electro-mechanically responsive ceramics that may be used, reference is made to Wainer Patents 2,402,515, 2,402,516 and 2,402,518, but the present invention is in no sense limited to those particular compositions.
  • electro-mechanically responsive elements capable of being formed into shapes disclosed herein will be referred to hereinafter simply as ceramics.
  • transducers herein disclosed are particularly adapted for the transmission or reception of supersonic vibrations in water for use in depth sounding, underwater ranging, etc., but since they are not limited to any particular frequency range, the vibrations will be referred to, for convenience, as sound, which term as used herein includes both the sonic and supersonic range of frequencres.
  • a transducer consisting of a fluid tight case 20 closed at the front end by a rubber cap 21 which has bonded thereto and supports a vibrator member 22.
  • the rubber cap 21 is preferably of a rubber having substantially the same soundtransmitting properties as the water or other fluid in which the transducer is to be immersed, so that it acts as a sound Window to transmit vibrations or sound from the vibrator element 22 through the window with substantially no reflection.
  • the cap 21 is shown as secured in fluidtight relation to the end of the case 20 by a band clamp 23.
  • the vibrator 22 consists of a stack of ceramic elements in the form of discs 24 bonded together by thin films of electrically conducting material such as silver.
  • the faces of the discs 24 may be coated with silver paint prior to assembly of the stack, and then placed together in the stack, and pressed together while subjecting them to heat in a furnace to fuse the silver and bond the discs together in a solid member.
  • the silver films on the outer ends of the end discs function as electrodes, whereas those between the discs function not only as electrodes but as bonding elements.
  • the film on the front face of the front ceramic disc 24 may be mechanically bonded to the rubber cap 21 with any suitable adhesive, many of which are well-known in the art.
  • One set of alternate electrodes 25 are connected together and to a circuit exterior of the case 20 by a lead 26, and the other set of alternate electrodes are connected together and to the external circuit by a lead 32. With this connection the different ceramic discs 24 are connected in parallel, electrically.
  • This has the substantial advantage of presenting a low impedance to the circuit connected to the leads 26 and 32, and make feasible a vibrator of this general type.
  • the vibrator consisted of a single, long cylinder of ceramic with only two electrodes at opposite ends thereof, the impedance of the unit would be extremely high, and it would be difiicult to match the impedance to conventional electrical circuits.
  • the primary mechanical forces developed in a ceramic are parallel to the electrical field therein; therefore the primary vibratory forces developed in the unit 22 are longitudinal, which is the useful direction.
  • the overall length of the vibrating member 22 should be onehalf wave length at the desired frequency of operation.
  • member 22 vibrates longitudinally at its natural or resonant frequency by alternate compression and expansion, and has much greater amplitude of movement than at other frequencies.
  • Such vibration develops severe compression and tensile forces in the body, and the tensile forces can be resisted only by a very strong bonding between the elements.
  • the necessary strength can be provided between ceramic elements by the bonding of silver fused thereto.
  • Fig; 2 shows a vibrator member 22a differing from the member 22 in Fig. 1 only in that it haslongitudinal holes 28 extending therethrough, and in having an end" plate 27 consisting of a solid rigid disc of some material such as aluminum.
  • the function of the plate 27 is to present a continuous surface to the rubber window 21 (Fig. l) and transmit the vibrations of the end of the member 22a to the window as a continuous piston.
  • the advantages of the vibratory member 22a over member 22 are as follows: The percentage of sound transmitted through the contact boundary of two mediais governed by the relative densities of the two media. The structure of member 22a quite effectively reduces the effective density of the vibrating member, thereby improving the efficiency of transmission. .This also lowers the mechanical Q of the vibrating member and broadens the frequency band over which it operates at maximum efiiciency.
  • Fig. 4 shows a vibrator member 22b diifering from member 221: of Fig. 2 only in having a rear end plate 30 ofrigid material bonded to the adjacent ceramic disc, to provide an'inert (with respect to e'lectro-mechanical properties) mass at the free end of the stack.
  • the plate 30 is shown in the drawing as a disc ofthe same diameter'as the ceramic discs 24b, but this is not essential.
  • the plate 30, by virtue of its mass, alters the resonant frequency of the vibrator, and increases the amplitude of vibration of the front (active) end. For the latter purpose, it may be made heavier than the plate 2711 at the front end. It also reduces the Q of the vibrator, which is .desirable in some applications.
  • inert rear end mass plate 30 is not restricted to the specific vibrator of Fig. 2, having apertured. discs, but is also applicable to the vibrator of Fig. lhaving solidceramic discs, and with or without an inert mass element (such as the plate 27 in Fig. 2) at the front end.
  • a transducer according to claim 1 in which a plurality of said elements consist of electromechanically-- responsiveceramicdielectric material and said conductive electrodes on juxtaposed faces 'of two adjacent ceramic elements consisting ofa metallic. film fused to said juxtaposed faces and constituting a mechanical bond therebetween.
  • a transducer accordingto claim 1 in which said member comprises an electromechanically-inert mass 616? ment at one end. w

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Transducers For Ultrasonic Waves (AREA)
  • Measurement Of Velocity Or Position Using Acoustic Or Ultrasonic Waves (AREA)
US272206A 1951-03-06 1952-02-18 Ceramic transducer having stacked elements Expired - Lifetime US2787777A (en)

Priority Applications (12)

Application Number Priority Date Filing Date Title
BE509494D BE509494A (is) 1951-03-06
BE511127D BE511127A (is) 1951-03-06
BE517616D BE517616A (is) 1951-03-06
US2733423D US2733423A (en) 1951-03-06 Ceramic transducers having annular elements
US272206A US2787777A (en) 1951-03-06 1952-02-18 Ceramic transducer having stacked elements
GB18976/53A GB718260A (en) 1951-03-06 1952-02-21 Ceramic transducer for underwater sound transmission and reception
GB4644/52A GB718203A (en) 1951-03-06 1952-02-21 Ceramic transducer for underwater sound transmission and reception
FR1054912D FR1054912A (fr) 1951-03-06 1952-02-22 Convertisseur à céramique destiné à l'émission ainsi qu'à la réception d'ondes soniques dans un fluide
FR63717D FR63717E (fr) 1951-03-06 1952-04-22 Convertisseur à céramique destiné à l'émission ainsi qu'à la réception d'ondessoniques dans un fluide
GB11834/52A GB716065A (en) 1951-03-06 1952-05-09 Improvements in or relating to transducers
GB3458/53A GB726330A (en) 1951-03-06 1953-02-06 Improvements in or relating to ceramic transducers for underwater transmission and reception of sound
FR63798D FR63798E (fr) 1951-03-06 1953-02-11 Convertisseur à céramique destiné à l'émission ainsi qu'à la réception d'ondes soniques dans un fluide

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US21414451A 1951-03-06 1951-03-06
US228956A US2774892A (en) 1951-05-29 1951-05-29 Annular vibrator with lumped loading
US272206A US2787777A (en) 1951-03-06 1952-02-18 Ceramic transducer having stacked elements

Publications (1)

Publication Number Publication Date
US2787777A true US2787777A (en) 1957-04-02

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US2733423D Expired - Lifetime US2733423A (en) 1951-03-06 Ceramic transducers having annular elements
US272206A Expired - Lifetime US2787777A (en) 1951-03-06 1952-02-18 Ceramic transducer having stacked elements

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Application Number Title Priority Date Filing Date
US2733423D Expired - Lifetime US2733423A (en) 1951-03-06 Ceramic transducers having annular elements

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US (2) US2787777A (is)
BE (3) BE517616A (is)
FR (3) FR1054912A (is)
GB (4) GB718203A (is)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3019660A (en) * 1956-04-26 1962-02-06 Gulton Ind Inc Ultrasonic transducer
US3068446A (en) * 1958-08-21 1962-12-11 Stanley L Ehrlich Tubular electrostrictive transducer with spaced electrodes and loading masses
US3230503A (en) * 1962-06-22 1966-01-18 Jr Jack Elliot Transducer
US3243767A (en) * 1962-04-30 1966-03-29 Paul M Kendig Electroacoustic transducer for detection of low level acoustic signals over a broad frequency range
US3336573A (en) * 1966-09-14 1967-08-15 Texaco Inc Crystal pressure sensitive geophones for use in soft earth
US3337843A (en) * 1965-12-20 1967-08-22 Paul M Kendig Underwater transducer array for deep submergence
US3453456A (en) * 1966-10-27 1969-07-01 Trw Inc Ultrasonic transducer
US3497727A (en) * 1968-03-28 1970-02-24 Westinghouse Electric Corp Multilayer thin film piezoelectric transducers
US3543058A (en) * 1969-11-10 1970-11-24 Westinghouse Electric Corp Piezoelectric transducer
US3662312A (en) * 1968-03-23 1972-05-09 Ferranti Ltd Semiconductor strain transducers
US4477783A (en) * 1982-08-19 1984-10-16 New York Institute Of Technology Transducer device

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3258739A (en) * 1966-06-28 Hurley etal hydrophones
DE1113400B (de) * 1953-08-14 1961-08-31 Bendix Corp UEbertrager fuer die Umformung von Schallwellen in einem fluessigen Medium in elektrische Wellen und umgekehrt
US2783449A (en) * 1953-08-28 1957-02-26 Texas Co Seismic velocity measurement
BE541365A (is) * 1955-07-13
US3018466A (en) * 1955-10-21 1962-01-23 Harris Transducer Corp Compensated hydrophone
US3094636A (en) * 1956-06-15 1963-06-18 Bendix Corp Underwater transducer
US3058014A (en) * 1958-09-08 1962-10-09 Bendix Corp Apparatus for generating sonic vibrations in liquids
US3079584A (en) * 1959-10-23 1963-02-26 Claude C Sims High pressure piezoelectric hydrophone with tungsten backing plate
US3242723A (en) * 1962-09-27 1966-03-29 Dwight J Evans Ultrasonic transducer
US3277451A (en) * 1963-11-21 1966-10-04 Edwin J Parssinen Wide angle broad band hydrophone array
US3319219A (en) * 1965-03-29 1967-05-09 Dynamics Corp Massa Div Electroacoustic transducer
US4156228A (en) * 1977-07-26 1979-05-22 Eg&G International, Inc. Acoustic transducer with acoustic isolating mounting base

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1450246A (en) * 1920-01-28 1923-04-03 Walter G Cady Piezo-electric resonator
US2233992A (en) * 1938-01-03 1941-03-04 Gulf Research Development Co Method of and apparatus for surveying wells
US2271200A (en) * 1939-07-19 1942-01-27 Bell Telephone Labor Inc Wave filter
US2426650A (en) * 1943-12-27 1947-09-02 Bell Telephone Labor Inc Method of soldering a terminal to a piezoelectric crystal
US2520938A (en) * 1944-10-07 1950-09-05 Klein Elias Tourmaline crystal transducer

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2405187A (en) * 1941-11-07 1946-08-06 Submarine Signal Co Piezoelectric transducer
US2404391A (en) * 1942-02-19 1946-07-23 Bell Telephone Labor Inc Prismatic and high power compressional-wave radiator and receiver
US2473354A (en) * 1942-11-20 1949-06-14 Submarine Signal Co Device for transmitting and receiving compressional waves
US2497901A (en) * 1944-08-18 1950-02-21 Bell Telephone Labor Inc Magnetostrictive transmitter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1450246A (en) * 1920-01-28 1923-04-03 Walter G Cady Piezo-electric resonator
US2233992A (en) * 1938-01-03 1941-03-04 Gulf Research Development Co Method of and apparatus for surveying wells
US2271200A (en) * 1939-07-19 1942-01-27 Bell Telephone Labor Inc Wave filter
US2426650A (en) * 1943-12-27 1947-09-02 Bell Telephone Labor Inc Method of soldering a terminal to a piezoelectric crystal
US2520938A (en) * 1944-10-07 1950-09-05 Klein Elias Tourmaline crystal transducer

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3019660A (en) * 1956-04-26 1962-02-06 Gulton Ind Inc Ultrasonic transducer
US3068446A (en) * 1958-08-21 1962-12-11 Stanley L Ehrlich Tubular electrostrictive transducer with spaced electrodes and loading masses
US3243767A (en) * 1962-04-30 1966-03-29 Paul M Kendig Electroacoustic transducer for detection of low level acoustic signals over a broad frequency range
US3230503A (en) * 1962-06-22 1966-01-18 Jr Jack Elliot Transducer
US3337843A (en) * 1965-12-20 1967-08-22 Paul M Kendig Underwater transducer array for deep submergence
US3336573A (en) * 1966-09-14 1967-08-15 Texaco Inc Crystal pressure sensitive geophones for use in soft earth
US3453456A (en) * 1966-10-27 1969-07-01 Trw Inc Ultrasonic transducer
US3662312A (en) * 1968-03-23 1972-05-09 Ferranti Ltd Semiconductor strain transducers
US3497727A (en) * 1968-03-28 1970-02-24 Westinghouse Electric Corp Multilayer thin film piezoelectric transducers
US3543058A (en) * 1969-11-10 1970-11-24 Westinghouse Electric Corp Piezoelectric transducer
US4477783A (en) * 1982-08-19 1984-10-16 New York Institute Of Technology Transducer device

Also Published As

Publication number Publication date
US2733423A (en) 1956-01-31
BE511127A (is)
GB718260A (en) 1954-11-10
GB716065A (en) 1954-09-29
BE517616A (is)
BE509494A (is)
GB726330A (en) 1955-03-16
FR63798E (fr) 1955-10-03
GB718203A (en) 1954-11-10
FR63717E (fr) 1955-10-03
FR1054912A (fr) 1954-02-15

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