US2480535A - Enclosure for vibratile elements - Google Patents

Enclosure for vibratile elements Download PDF

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Publication number
US2480535A
US2480535A US734360A US73436047A US2480535A US 2480535 A US2480535 A US 2480535A US 734360 A US734360 A US 734360A US 73436047 A US73436047 A US 73436047A US 2480535 A US2480535 A US 2480535A
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United States
Prior art keywords
crystal
faces
elements
plastic
face
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Expired - Lifetime
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US734360A
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English (en)
Inventor
Frank J Alois
Richard W Samsel
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General Electric Co
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General Electric Co
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Priority to NL71368D priority Critical patent/NL71368C/xx
Application filed by General Electric Co filed Critical General Electric Co
Priority to US734360A priority patent/US2480535A/en
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Publication of US2480535A publication Critical patent/US2480535A/en
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    • G—PHYSICS
    • G10—MUSICAL INSTRUMENTS; ACOUSTICS
    • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
    • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
    • G10K11/02—Mechanical acoustic impedances; Impedance matching, e.g. by horns; Acoustic resonators
    • 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

Definitions

  • This invention is directed to an enclosure for vibratile elements, and is particularly related to the manufacture of piezo-electric crystal transducers for underwater sound transmission and reception.
  • the invention also relates to improved completely enclosed unitary piezo-electric crystal transducers.
  • An object of the invention is to provide an improved casing for vibratile elements. Another object is to provide an improved method of making devices incorporating vibratile elements in a waterproof structure.
  • a more specific object of the invention is to provide a piezo-electric crystal transducer wherein the crystal elements are totally encased in a solid block of a plastic material, such as a polymerized unsaturated polyester resin.
  • Fig. 1 is a partially cutaway view of a piezo-electric crystal transducer constructed-in accordance with the invention
  • Fig. 2 is a view showing a group of piezo-electric crystals arranged in accordance with the preferred embodiment of the invention showing the crystal elements, metal foil electrodes for the elements and resilient non-damping members, shown partially cutaway, arranged about and between the elements
  • Figs. 3, 4 and 5 are partially cutaway side views illustrative of steps in the manufacture of a complete transducer of the type shown in Fig. 1.
  • the device shown in Fig. 1 is an eflicient receiving or transmitting transducer for operation at sonic or supersonic frequencies wherein the crystal elements are hermetically sealed within a block of solid plastic material.
  • the transducer as shown in Fig. 1, comprises a plurality of piezoelectric crystal elements I, which are preferably of ammonium dihydrogen orthophosphate, although Rochelle salt, quartz or other piezo-electric crystal material may be used. Electrodes and associated conductors in the form of thin conductive metal foil are provided for each crystal as best shown by the heavy lines II to 24 inclusive in Fig.
  • Each of the crystal elements is isolated from the casing by covering all except an upper -operative face which comprises one of the minor faces, with blocks 2 of a soft material such as that known by the tradename Corprene, a granular cork material formed with a suitable binder.
  • a suitable material is one that provides a minimum of mechanical loading of the crystal by absorbing only a small amount of the vibratory energy. Materials possessing this property are referred to herein as soft mate- Piezo-electric transducers have been heretofore used for transmitting and receiving sonic and supersonic energy in depth indicators and in underwater object locating equipments, and various means of protecting the crystal elements from water have been suggested.
  • an eflicient transducer comprising a completely enclosed crystal element, or group of elements, wherein the casing consists of a unitary structure permanently protecting the crystals from damage from liquids and other hazards.
  • One of the principal diificulties heretofore encountered. in constructions of this type has been that vibration-transmitting materials either cannot be bonded to an operative vibratory face of the crystal element or will destroy the crystal element due to difference in expansion due to temperature changes, or due to shrinkage during manufacture.
  • Electric connections including conductors 3 and 4 are made to the metal foil electrodes and a coil or transformer 5 may be connected in series or in parallel with the foil electrodes if required to provide proper electrical impedance for the device.
  • the electrical connections are shown as terminating in a concentric cable comprising an inner conductor 6 and an outer shielding conductor I with interposed insulating material 8, the cable being provided for completing connections to any apparatus which may be used in association with the transducer. All of the transducer elements mentioned above are enclosed in a solid block 9 of hard plastic material preferably comprising an unsaturated polyester resin as later discussed.
  • the crystal elements I will vibrate efi'lciently when excited and that vibratory energy will be transmitted efiectively through the plastic layer to or from face III of the plastic block if a layer, film or thin coating Illa of suitablecement is provided across the top or operative ininor faces of the crystals separating the operative faces from the plastic material, and that the etficiency of transmission is increased if the layer or film is under compression.
  • the foil electrodes and foil conductors for carrying current to the electrodes are numbered ll through 24 and are arranged as indicated by the heavy lines denoting the edges of the foil members.
  • a connection is established from the foil end ll along the back face of one of the end crystals by an electrode l2, and through connecting foil sheet l3 along one face of each of four intermediate crystal-s by electrodes l4 and I5, as well as to the outer faces of two additional crystal elements by electrode l6, and the inner face of the remaining end element by electrode l1.
  • Connections are also established from foil end l8 to electrode ill on the outer face of the last mentioned end element and through foil sheet 20 to electrodes 2
  • each pair of crystal elements Separating adjacent major faces of each pair of crystal elements is a block or sheet of soft, vibration-isolating material 2 and completely enclosing the group of elements, except on the top operative face, are similar blocks 2. It will be noted that a relatively thick block 25 completely covers the under face of the group of crystals. All of these blocks are preferably of the soft material mentioned above.
  • the interposition of the soft mass between adjacent crystal faces and between the faces and the plastic block serves to isolate the vibrating faces of the crystals, excepting of course the top face of each, from the casing and from the faces of adjacent crystals without imposing more than a small mechanical loading on the vibratory faces.
  • the preferred method is to apply the strips of metal foil to the desired crystal faces using any cement which is capable of bonding to the foil and to the crystal surfaces.
  • a suitable cement may prove to be nonconductive, and if so, the foil may be pressed against the face of the crystal by rubbing the foil with the rounded tip of a suitable instrument to cause small areas of the foil to directly contact the crystal face.
  • Types of cement found suitable include those commonly used for cementing foil electrodes to crystals, such as that identified as BC-6052 sold by the Bakelite Corporation.
  • Fig. 2 accordingly comprises a group of eight crystal elements, each of the elements being provided with two electrodes on opposite major faces respectively connected to foil ends II and it. Each of the elements is enclosed on five sides or faces by the soft material,'leaving'only the-upper operative minor face of each element uncovered.
  • the crystal unit of Fig. 2 is encased in the solid plastic material by the remaining steps in the construction, which are best explained with reference to Figs. 3, 4 and 5.
  • the unit of Fig. 2 is first coated completely across the upper exposed face with a layer of black neoprene-base cement to a thickness of between /61 to 5; inch.
  • the cement layer is indicated as layer Illa in Fig. 1.
  • This cement may be of the type supplied by the Union Bay State Company of Cambridge, Massachusetts, identified as N-521. which is a chlorobutadiene polymer with a suitable accelerator, although other types of cement with a rubber or neoprene base may be utilized.
  • the cement layer serves to complete a bond between the faces of the crystal elements and the solid plastic material of the encasing block 9.
  • the foil ends are wrapped tightly around and soldered to short conductive wires 26.
  • a glass mold is now prepared in the shape shown in Fig. 3 such as by cementing a flat glass plate 21 to the periphery of one end of a hollow glass cylinder 28.
  • a liquid plastic Into the bottom of the vessel thus formed is poured a liquid plastic to a depth of about A inch which is allowed to solidify to form a block 29 in the bottom of the vessel.
  • the liquid plastic which is poured into the vessel may be that sold under the trade name Selectron" by the Pittsburgh Plate Glass Company identified as No. 5003 which comprises about 70% polystyrene with about 30% methacrylate resin.
  • a suitable quantity of catalyst such as tertiary butyl diperphthalate dissolved in styrene monomer.
  • catalyst such as tertiary butyl diperphthalate dissolved in styrene monomer.
  • Such material when maintained at a temperature of approximately 60 C. for about /2 hour will be found to be polymerized into a hard amber colored plastic material, which will be electrically insulating and capable of transmitting sound or supersonic energy.
  • conductors 3 and l are soldered or otherwise connected to the ends of conductors 28 which protrude from the now solid block of plastic encasing the crystal element structure. More of the liquid plastic may now be poured in to the level 3
  • the mold may be brokenaway yielding the complete transducer shown in Fig. 1.
  • the plastic material selected for encasing the crystal unit should be one which, like that described above, contracts slightly on hardening so that the crystal elements are tightly bound with the block, and so that the layer or film of rubber, or rubber-like, cementitious material l0a across the operative faces of the crystals is compressed between the plastic casing and the crystalfaces. This compression improves the vibration transmission through the layer of cement and tends to maintain the bonds between the cement and plastic and between the cement and crystal faces. It is desirable to use a plastic material which will not adhere to glass to permit removal of the finished transducer from the glass mold without destroying the mold. If it is found that the plastic material polymerizes too rapidly, generating too much heat, an inhibitor such as a saturated solution of quinone dissolved in benzene may be added to the liquid.
  • the block with a face Ill other than flat as shown such as convex or concave, to utilize the plastic material as a lens between the crystal faces and the outside medium.
  • the hard plastic material is adapted for such use as a lens because the velocity of sound in the plastic differs from the velocity in water.
  • vibration of the elements of a transmitting transducer may be produced by electrostatic or electromagnetic coupling from devices outside the plastic block, rather than by electrical connections extending into the block to electrodes attached to the eleagainst ments as shown.
  • pickup of the energy produced by the vibrations imposed on the elements may be similarly arranged.
  • a transducer comprising a vibratile element having an operative vibratory face, a thin layer of rubber-like cement bonded to said face, a solid plastic block completely embedding said element and in contact with said layer, and a soft mass interposed between said element and said plastic of sufficient quantity to minimize damping of said element.
  • a moisture-proof underwater transducer comprising a vibratile element with an operative face, a thin coating of a cement,,of rubber-like base on said face, a soft material mass enclosing said element except for said face, and a solid plastic block completely enclosing said element and said members and arranged to permit vibratory energy transmission through said coating and through said plastic block between said face and the medium in external contact with said block.
  • a transducer comprising a plurality of crystal elements each having an operative face, said operative faces being disposed in a plane, a coating of rubber-like cementitious material across said faces. spacers of soft material arranged all of the remaining faces of each of said elements, a solid hard plastic block completely encasing said elements and compressing said cementitious coating against the faces of said elements whereby said elements are hermetically sealed within said block, and conducting means sealed into said block comprising electrodes for said crystal elements.
  • a transducer comprising a vibratile element with at least two vibratory faces, a layer of rubher-like material bonded to one of said faces, a
  • casing for said element compressing said layer against said one of said faces and forming a vibration-transmitting path from said one of said faces, and isolating means interposed between the other of said faces and said casing.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Multimedia (AREA)
  • Transducers For Ultrasonic Waves (AREA)
US734360A 1947-03-13 1947-03-13 Enclosure for vibratile elements Expired - Lifetime US2480535A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
NL71368D NL71368C (enrdf_load_html_response) 1947-03-13
US734360A US2480535A (en) 1947-03-13 1947-03-13 Enclosure for vibratile elements

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Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2558563A (en) * 1948-10-29 1951-06-26 Gen Electric Piezoelectric strain gauge
US2594948A (en) * 1947-10-30 1952-04-29 Brush Dev Co Electromechanical transducer unit
US2613261A (en) * 1948-12-08 1952-10-07 Massa Frank Underwater transducer
US2638577A (en) * 1949-11-15 1953-05-12 Harris Transducer Corp Transducer
US2707755A (en) * 1950-07-20 1955-05-03 Sperry Prod Inc High absorption backings for ultrasonic crystals
US2761117A (en) * 1952-01-16 1956-08-28 Charles E Green Directional transducer
US2830204A (en) * 1955-07-01 1958-04-08 Harris Transducer Corp Linear mechanical oscillator circuit element transducer
US2879496A (en) * 1948-09-30 1959-03-24 Research Corp Plastic cast ring stack transducer
US2931223A (en) * 1954-12-10 1960-04-05 Kritz Jack Transducers for acoustic flowmeter
US2943297A (en) * 1950-04-27 1960-06-28 Raymond L Steinberger Multiple element electroacoustic transducer
US2949772A (en) * 1954-12-10 1960-08-23 Kritz Jack Flowmeter
US3027540A (en) * 1957-09-23 1962-03-27 Gulton Ind Inc Hydrophone with spaced electromechanical ceramic elements
US3068446A (en) * 1958-08-21 1962-12-11 Stanley L Ehrlich Tubular electrostrictive transducer with spaced electrodes and loading masses
US3212056A (en) * 1961-06-22 1965-10-12 Electronic Res Associates Inc Dual transducer device
US4054808A (en) * 1974-08-19 1977-10-18 Matsushita Electric Industrial Co., Ltd. Vibration detecting device having a piezoelectric ceramic plate and a method for adapting the same for use in musical instruments
US4282453A (en) * 1977-02-21 1981-08-04 Australasian Training Aids (Pty.) Ltd. Transducer apparatus for detecting airborne pressure pulse
US4359659A (en) * 1979-02-27 1982-11-16 Australasian Training Aids (Pty.) Limited Piezoelectric shock wave detector
US4859897A (en) * 1988-04-07 1989-08-22 Frank Massa Directional waterproof ultrasonic transducer for operating in air

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2386692A (en) * 1944-04-05 1945-10-09 Walter E Kuenstler Crystal
US2402531A (en) * 1944-03-28 1946-06-25 Brush Dev Co Transducer

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2402531A (en) * 1944-03-28 1946-06-25 Brush Dev Co Transducer
US2386692A (en) * 1944-04-05 1945-10-09 Walter E Kuenstler Crystal

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2594948A (en) * 1947-10-30 1952-04-29 Brush Dev Co Electromechanical transducer unit
US2879496A (en) * 1948-09-30 1959-03-24 Research Corp Plastic cast ring stack transducer
US2558563A (en) * 1948-10-29 1951-06-26 Gen Electric Piezoelectric strain gauge
US2613261A (en) * 1948-12-08 1952-10-07 Massa Frank Underwater transducer
US2638577A (en) * 1949-11-15 1953-05-12 Harris Transducer Corp Transducer
US2943297A (en) * 1950-04-27 1960-06-28 Raymond L Steinberger Multiple element electroacoustic transducer
US2707755A (en) * 1950-07-20 1955-05-03 Sperry Prod Inc High absorption backings for ultrasonic crystals
US2761117A (en) * 1952-01-16 1956-08-28 Charles E Green Directional transducer
US2931223A (en) * 1954-12-10 1960-04-05 Kritz Jack Transducers for acoustic flowmeter
US2949772A (en) * 1954-12-10 1960-08-23 Kritz Jack Flowmeter
US2830204A (en) * 1955-07-01 1958-04-08 Harris Transducer Corp Linear mechanical oscillator circuit element transducer
US3027540A (en) * 1957-09-23 1962-03-27 Gulton Ind Inc Hydrophone with spaced electromechanical ceramic elements
US3068446A (en) * 1958-08-21 1962-12-11 Stanley L Ehrlich Tubular electrostrictive transducer with spaced electrodes and loading masses
US3212056A (en) * 1961-06-22 1965-10-12 Electronic Res Associates Inc Dual transducer device
US4054808A (en) * 1974-08-19 1977-10-18 Matsushita Electric Industrial Co., Ltd. Vibration detecting device having a piezoelectric ceramic plate and a method for adapting the same for use in musical instruments
US4282453A (en) * 1977-02-21 1981-08-04 Australasian Training Aids (Pty.) Ltd. Transducer apparatus for detecting airborne pressure pulse
US4359659A (en) * 1979-02-27 1982-11-16 Australasian Training Aids (Pty.) Limited Piezoelectric shock wave detector
US4859897A (en) * 1988-04-07 1989-08-22 Frank Massa Directional waterproof ultrasonic transducer for operating in air

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