US3614335A - Electroacoustic transducer held together by thermoplastic clamping ring - Google Patents

Electroacoustic transducer held together by thermoplastic clamping ring Download PDF

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Publication number
US3614335A
US3614335A US846034A US3614335DA US3614335A US 3614335 A US3614335 A US 3614335A US 846034 A US846034 A US 846034A US 3614335D A US3614335D A US 3614335DA US 3614335 A US3614335 A US 3614335A
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US
United States
Prior art keywords
clamping ring
transducer
diaphragm
flat
yoke
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
US846034A
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English (en)
Inventor
Leslie Eugene Dymoke-Bradshaw
Norman William Tester
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.)
STC PLC
Original Assignee
International Standard Electric Corp
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Filing date
Publication date
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
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Publication of US3614335A publication Critical patent/US3614335A/en
Assigned to STC PLC reassignment STC PLC ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: INTERNATIONAL STANDARD ELECTRIC CORPORATION, A DE CORP.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/02—Details
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/16—Mounting or tensioning of diaphragms or cones
    • H04R7/18—Mounting or tensioning of diaphragms or cones at the periphery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/02—Details
    • H04R9/025—Magnetic circuit

Definitions

  • thermoplastic clamping ring has an in tegral flange which provides spaces between the magnetic system and the diaphragm.
  • Acoustic damping is provided by a .nonmagnetic grid located behind a voice coil and coupled acoustically to the space behind the diaphragm.
  • This invention relates to electroacoustic transducers.
  • an electroacoustic transducer in which the front cover, back cover and diaphragm are held together by a cylindrical thermoplastic clamping ring which has its two ends heat sealed over the front and back covers respectively.
  • a moving coil electroacoustic transducer in which the magnetic structure consists of a solid cylindrical permanent magnet topped by an inner pole piece of soft magnetic material and encased concentrically by a cup-shaped yoke of soft magnetic material, in which a diaphragm carries a voice coil which rests in the annular airgap between the inner pole piece and the yoke, in which part of the yoke forms the back cover of the transducer, and in which the back cover, diaphragm and front cover are held together by a cylindrical clamping ring, with the diaphragm being located on an inwardly extending flange of the clamping ring and the two ends of the clamping ring being formed over the back and front covers of the transducer respectively.
  • a moving coil clectroacoustic transducer in which the magnetic structure consists of a solid cylindrical permanent magnet topped by an inner pole piece of soft magnetic material and encased concentrically by a cup-shaped yoke of soft magnetic material, in which a diaphragm carries a voice coil which rests in the annular airgap between the inner pole piece and the yoke, in which part of the yoke forms the back cover of the transducer, and in which sound equalization is achieved by a damping grid behind the moving coil having one or more holes leading to an otherwise closed space between the permanent magnet and the yoke, and by one or more holes in the front cover of the transducer which also serve for the ingress or egress of sound.
  • FlG. 1 shows a cross section view, along the line A-A of FIG. 2 of a moving coil transducer according to the invention
  • FlG. 2 shows a plan view of the moving coil transducer shown in FIG. ll
  • FIG. 3 illustrates modification to the transducer shown in FIGS. 1 and 2 with regard to securing the permanent magnet of the assembly
  • FIG. A shows a section view of the clamping ring before it is used to hold together the assembly of parts of the transducer shown in F108. 1 and 2, or FIGS. 1 and 2 as modified by FIG. 3.
  • a solid cylindrical permanent magnet 111 of columnar material such as Ticonal GX
  • a cup-shaped yoke of mild steel concentrically encases the permanent magnet the yoke being made up of a generally frustoconical pot 12, which forms the back cover of the transducer, and a flat annular pole piece 113.
  • a plastic diaphragm has a dome-shaped inner portion M and a flat rim 15.
  • the diaphragm carries a voice coil 16 which rests in the annular airgap between the inner pole piece 111 and the outer pole piece 113.
  • a damping grip 17, of nonmagnetic metal, is in the form of an annular trough behind the voice-coil 1b with its inner rim attached to the inner pole piece 11 and it outer rim attached to the outer pole piece 13
  • the damping grid 17, has one or more holes 171 leading to an otherwise closed space between the permanent magnet and the yoke.
  • FIG. 3 shows a modification to the shape of the pct 12 in which the magnet is secured by making it a press fit.
  • the larger end of the pot 12 has an outwardly extending flat lip 121 on which rests the flat annular outer pole piece 113.
  • the pot 12 and the outer pole piece 13 are held together by a cylindrical clamping ring 18 (see also FIG. 1) of thermoplastic-insulating material,
  • the flat rim 15 of the diaphragm is located on the outer side of the flange 1M.
  • the other end 11131 of the clamping ring 1% is heat sealed over the flat rim 2111, thus clamping the diaphragm between the flange 1M and the washer 19 and holding the front cover 20 and diaphragm to the magnetic assembly of the transducer.
  • the clamping ring 13 has an outwardly extending rib WA into which the two terminals 21, e.g., of brass, are secured.
  • Each electrical lead 161 of the voice coil 16 extends along a groove in the flange 1181 and through a hole or slot in the side of the clamping ring 18 and is laid over the top of the respective terminal 21 by locating it in a groove 1185 in the outer lip of the rib 11M.
  • the leads 161 are soldered or welded to the terminals 21 and are protected by sealing material 22 in the upper surface of the rib 111 1.
  • a preferred method of manufacture of the diaphragm is to form it between heated male and female tools, followed by suitable cooling.
  • the coil is made of solderable enameled copper wire coated with an adhesive and is self supporting, requiring no former.
  • Ticonal GX type-material is chosen for the permanent magnet working at its (Bl-1) maximum point, where B is the flux density in the permanent magnet and H is the magnetizing force in the permanent magnet.
  • This material is chosen because it has a low value of A/(BH),,,,,,,, where A is the density of the material, so as to achieve a low weight of magnet to provide a given flux density in a given airgap.
  • the antiresonant type of frequency response equalization is chosen for the transducer. This is achieved by the hole or holes 171 in the damping grid 17 behind the moving coil.
  • the frequency response is also modified by one or more holes 202 in the front plate 20.
  • the holes 171 and 202 may be damped by covering them with fabric or by making them in the fonn of louvres.
  • the hole or holes 201 also serve for the ingress or egress of sound.
  • G Z The magnetic efficiency factor G Z where G, the force factor, is defined as force per unit current or flux density in the airgap X conductor length and Z is the AC impedance of the winding, is optimized to achieve a flux density of the order of 7,500 lines per square cm. it is found that high sensitivity occurs for a magnet in the region of 5 to 10 grams and for an airgap 0.1 cm. long.
  • the weight of the complete transducer capsule is of the order of 18 grams, and the overall diameter and overall depth of the transducer capsule are approximately one inch and three-quarters of an inch respectively.
  • the above-described transducer is of small size and lightweight and can be used both as the transmitter and as the receiver of a telephone set. Modifications to the frequency response that may be required for these two different applications may be obtained by adjusting the acoustic mass and resistance of the holes in the associated mouthpiece or earcap and/or by adjusting the volume between the transducer front plate and the earcap or mouthpiece. if a cut in sensitivity at low frequencies is required this can be achieved by making one or more holes in the diaphragm.
  • the transducer has lower distortion than the rocking-armature type.
  • the transducer As a transmitter the transducer has the advantages of lower distortion than the carbon transmitter and does not suffer from burning noise. Because of its lower sensitivity than the carbon transmitter it must be used in conjunction with a transistor amplifier in the telephone set. However, the carbon transmitter, when subjected to much use, e.g., in public phone kiosks, and, more particularly when used in dirty locations such as railway stations and coal mines, becomes contaminated and replacement is frequent. The moving coil transducer (and amplifier) does not, of course, suffer from this defeet and, being inherently more reliable, ensures fewer replacements.
  • An electroacoustic transducer comprising a front cover, a back cover and a diaphragm, means holding said front cover, said back cover and said diaphragm together including a cylindrical thermoplastic-clamping ring, in which said thermoplastic-clamping ring includes two ends which are heat sealed over the front and back covers respectively, the diaphragm of the assembly is located on an inwardly extending flange of the clamping ring, the two ends of the clamping ring are formed over the back and front covers of the assembly respectively, and the clamping ring is of thermoplastic-insulating material and has an outwardly extending rib in which the terminals of the transducer are secured.
  • a moving coil electroacoustic transducer comprising a front cover, a magnetic structure, a diaphragm and a back cover, in which the front cover is formed of a flat piece of mild steel having a flat outer rim, the magnetic structure consists of a solid cylindrical permanent magnet topped by an inner pole piece of soft magnetic material and encased concentrically by a cup-shaped yoke of soft magnetic material, the diaphragm carries a voice coil which rests in an annular airgap between the inner pole piece and the yoke, the back cover is formed using part of the yoke, and the back cover, diaphragm, and the front cover are held together by a cylindrical clamping ring, the clamping ring is formed of thermoplastic-insulating material, the diaphragm is located on an inwardly extending flange integral to the clamping ring and the two ends of the clamping ring are formed over the back and front covers of the transducer respectively.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Multimedia (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
  • Headphones And Earphones (AREA)
US846034A 1968-08-08 1969-07-30 Electroacoustic transducer held together by thermoplastic clamping ring Expired - Lifetime US3614335A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB37939/68A GB1219918A (en) 1968-08-08 1968-08-08 Improvements in and relating to moving coil transducers

Publications (1)

Publication Number Publication Date
US3614335A true US3614335A (en) 1971-10-19

Family

ID=10400082

Family Applications (1)

Application Number Title Priority Date Filing Date
US846034A Expired - Lifetime US3614335A (en) 1968-08-08 1969-07-30 Electroacoustic transducer held together by thermoplastic clamping ring

Country Status (7)

Country Link
US (1) US3614335A (enrdf_load_stackoverflow)
CA (1) CA918798A (enrdf_load_stackoverflow)
CH (1) CH505525A (enrdf_load_stackoverflow)
DE (1) DE1939837A1 (enrdf_load_stackoverflow)
ES (1) ES370321A1 (enrdf_load_stackoverflow)
FR (1) FR2019332A1 (enrdf_load_stackoverflow)
GB (1) GB1219918A (enrdf_load_stackoverflow)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57196698A (en) * 1981-05-22 1982-12-02 Int Standard Electric Corp Dynamic converter and method of producing same
US4507800A (en) * 1982-01-06 1985-03-26 Analog & Digital Systems, Inc. Enclosed magnet loudspeaker
US5610989A (en) * 1989-12-21 1997-03-11 Knowles Electronics Co. Coil assemblies
US6185809B1 (en) * 1996-06-19 2001-02-13 Akg Acoustics Gmbh Method of manufacturing a diaphragm for an electroacoustic transducer
US20030081807A1 (en) * 2001-10-30 2003-05-01 Citizen Electronics, Co., Ltd. Speaker and method for manufacturing the speaker
US20040062414A1 (en) * 2001-11-14 2004-04-01 Shinji Kobayashi Speaker
WO2015124437A1 (de) * 2014-02-19 2015-08-27 Harman Becker Automotive Systems Gmbh Lautsprecher
US9154864B1 (en) * 2014-04-30 2015-10-06 Harman International Industries, Inc. Speaker assembly
US20150304781A1 (en) * 2012-12-25 2015-10-22 Kyocera Corporation Acoustic generator, acoustic generation device, and electronic device
EP2966880A1 (en) * 2014-07-08 2016-01-13 Harman International Industries, Incorporated Speaker assembly
US9338557B2 (en) * 2012-12-25 2016-05-10 Kyocera Corporation Acoustic generator, acoustic generation device, and electronic device
US9380365B2 (en) * 2012-12-17 2016-06-28 Kyocera Corporation Acoustic generator, acoustic generation device, and electronic device
US20170180837A1 (en) * 2015-12-17 2017-06-22 Delphi Technologies, Inc. Sound emitter device
US9872109B2 (en) 2014-12-17 2018-01-16 Knowles Electronics, Llc Shared coil receiver

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1659551B1 (de) * 1967-01-21 1972-05-25 Braas & Co Gmbh Distanzausgleichplaettchen fuer Verkleidungsplatten
GB1531791A (en) * 1976-03-17 1978-11-08 Rank Organisation Ltd Transducers
FR2363255A1 (fr) * 1976-08-27 1978-03-24 Bose Corp Haut-parleur et procede de fabrication
DE2929432C2 (de) * 1979-07-20 1981-08-13 Telefonbau Und Normalzeit Gmbh, 6000 Frankfurt Verfahren zur Herstellung eines elektrodynamischen Wandlers

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1847702A (en) * 1931-05-02 1932-03-01 Bell Telephone Labor Inc Sound translating device
US1915358A (en) * 1930-04-11 1933-06-27 Bell Telephone Labor Inc Electrodynamic device
US2293078A (en) * 1939-12-05 1942-08-18 B A Proctor Company Inc Microphone
US2458158A (en) * 1942-11-25 1949-01-04 Permoflux Corp Magnetically shielded electrodynamic sound reproducer
US2523802A (en) * 1949-08-06 1950-09-26 Joseph D Zimmerman Electrodynamic pillow-type loudspeaker
US2585052A (en) * 1948-04-23 1952-02-12 Int Standard Electric Corp Granule type acoustic transducer
DE1121654B (de) * 1960-08-31 1962-01-11 Siemens Ag Verfahren und Zentrierring zum Zentrieren der Schwingspule eines elektroakustischen Wandlers mit Ringspaltmagnetsystem
DE1153421B (de) * 1959-01-14 1963-08-29 Peiker Acustic Fabrik Elektroa Elektrodynamisches Schallgeraet
CH407233A (de) * 1963-12-14 1966-02-15 Peiker Heinrich Elektroakustischer Wandler

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1915358A (en) * 1930-04-11 1933-06-27 Bell Telephone Labor Inc Electrodynamic device
US1847702A (en) * 1931-05-02 1932-03-01 Bell Telephone Labor Inc Sound translating device
US2293078A (en) * 1939-12-05 1942-08-18 B A Proctor Company Inc Microphone
US2458158A (en) * 1942-11-25 1949-01-04 Permoflux Corp Magnetically shielded electrodynamic sound reproducer
US2585052A (en) * 1948-04-23 1952-02-12 Int Standard Electric Corp Granule type acoustic transducer
US2523802A (en) * 1949-08-06 1950-09-26 Joseph D Zimmerman Electrodynamic pillow-type loudspeaker
DE1153421B (de) * 1959-01-14 1963-08-29 Peiker Acustic Fabrik Elektroa Elektrodynamisches Schallgeraet
DE1121654B (de) * 1960-08-31 1962-01-11 Siemens Ag Verfahren und Zentrierring zum Zentrieren der Schwingspule eines elektroakustischen Wandlers mit Ringspaltmagnetsystem
CH407233A (de) * 1963-12-14 1966-02-15 Peiker Heinrich Elektroakustischer Wandler

Cited By (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57196698A (en) * 1981-05-22 1982-12-02 Int Standard Electric Corp Dynamic converter and method of producing same
US4507800A (en) * 1982-01-06 1985-03-26 Analog & Digital Systems, Inc. Enclosed magnet loudspeaker
US5610989A (en) * 1989-12-21 1997-03-11 Knowles Electronics Co. Coil assemblies
US5708721A (en) * 1989-12-21 1998-01-13 Knowles Electronics Co. Coil assemblies
US6185809B1 (en) * 1996-06-19 2001-02-13 Akg Acoustics Gmbh Method of manufacturing a diaphragm for an electroacoustic transducer
US20030081807A1 (en) * 2001-10-30 2003-05-01 Citizen Electronics, Co., Ltd. Speaker and method for manufacturing the speaker
US7266213B2 (en) * 2001-10-30 2007-09-04 Citizen Electronics Co., Ltd. Compact speaker with a protective cover
EP1315400A3 (en) * 2001-10-30 2008-03-05 Citizen Electronics Co., Ltd. Speaker and method for manufacturing the speaker
US20040062414A1 (en) * 2001-11-14 2004-04-01 Shinji Kobayashi Speaker
US7324658B2 (en) * 2001-11-14 2008-01-29 Sony Corporation Speaker
US9380365B2 (en) * 2012-12-17 2016-06-28 Kyocera Corporation Acoustic generator, acoustic generation device, and electronic device
US9338557B2 (en) * 2012-12-25 2016-05-10 Kyocera Corporation Acoustic generator, acoustic generation device, and electronic device
US20150304781A1 (en) * 2012-12-25 2015-10-22 Kyocera Corporation Acoustic generator, acoustic generation device, and electronic device
US9338558B2 (en) * 2012-12-25 2016-05-10 Kyocera Corporation Acoustic generator, acoustic generation device, and electronic device
US10015611B2 (en) 2014-02-19 2018-07-03 Harman Becker Automotive Systems Gmbh Loudspeaker
WO2015124437A1 (de) * 2014-02-19 2015-08-27 Harman Becker Automotive Systems Gmbh Lautsprecher
US9154864B1 (en) * 2014-04-30 2015-10-06 Harman International Industries, Inc. Speaker assembly
CN105282633A (zh) * 2014-07-08 2016-01-27 哈曼国际工业有限公司 扬声器总成
US20160014523A1 (en) * 2014-07-08 2016-01-14 Harman International Industries, Incorporated Speaker Assembly
US9723410B2 (en) * 2014-07-08 2017-08-01 Harman International Industries, Incorporated Speaker assembly
EP2966880A1 (en) * 2014-07-08 2016-01-13 Harman International Industries, Incorporated Speaker assembly
CN105282633B (zh) * 2014-07-08 2019-12-17 哈曼国际工业有限公司 扬声器总成
US9872109B2 (en) 2014-12-17 2018-01-16 Knowles Electronics, Llc Shared coil receiver
US20170180837A1 (en) * 2015-12-17 2017-06-22 Delphi Technologies, Inc. Sound emitter device
CN106899917A (zh) * 2015-12-17 2017-06-27 戴尔菲技术公司 发声器装置
US10021469B2 (en) * 2015-12-17 2018-07-10 Delphi Technologies, Inc. Sound emitter device
CN106899917B (zh) * 2015-12-17 2020-04-07 戴尔菲技术公司 发声器装置

Also Published As

Publication number Publication date
CH505525A (de) 1971-03-31
GB1219918A (en) 1971-01-20
CA918798A (en) 1973-01-09
ES370321A1 (es) 1971-05-16
DE1939837A1 (de) 1970-02-19
FR2019332A1 (enrdf_load_stackoverflow) 1970-07-03

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Legal Events

Date Code Title Description
AS Assignment

Owner name: STC PLC,ENGLAND

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:INTERNATIONAL STANDARD ELECTRIC CORPORATION, A DE CORP.;REEL/FRAME:004761/0721

Effective date: 19870423

Owner name: STC PLC, 10 MALTRAVERS STREET, LONDON, WC2R 3HA, E

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:INTERNATIONAL STANDARD ELECTRIC CORPORATION, A DE CORP.;REEL/FRAME:004761/0721

Effective date: 19870423