US3342953A - Electro-acoustic transducer - Google Patents

Electro-acoustic transducer Download PDF

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Publication number
US3342953A
US3342953A US315584A US31558463A US3342953A US 3342953 A US3342953 A US 3342953A US 315584 A US315584 A US 315584A US 31558463 A US31558463 A US 31558463A US 3342953 A US3342953 A US 3342953A
Authority
US
United States
Prior art keywords
permanent magnet
annular
pole piece
electro
air gap
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
US315584A
Other languages
English (en)
Inventor
Pless Ernst
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.)
AKG Acoustics GmbH
Original Assignee
AKG Akustische und Kino Geraete GmbH
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
Application filed by AKG Akustische und Kino Geraete GmbH filed Critical AKG Akustische und Kino Geraete GmbH
Application granted granted Critical
Publication of US3342953A publication Critical patent/US3342953A/en
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
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • 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
    • H04R1/06—Arranging circuit leads; Relieving strain on circuit leads
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
    • H04R31/006—Interconnection of transducer parts
    • 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
    • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
    • H04R9/02—Details
    • H04R9/025—Magnetic circuit
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
    • H04R2201/34—Directing or guiding sound by means of a phase plug
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2209/00—Details of transducers of the moving-coil, moving-strip, or moving-wire type covered by H04R9/00 but not provided for in any of its subgroups
    • H04R2209/024—Manufacturing aspects of the magnetic circuit of loudspeaker or microphone transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2400/00—Loudspeakers
    • H04R2400/11—Aspects regarding the frame of loudspeaker transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2499/00—Aspects covered by H04R or H04S not otherwise provided for in their subgroups
    • H04R2499/10—General applications
    • H04R2499/13—Acoustic transducers and sound field adaptation in vehicles

Definitions

  • a magnetic loudspeaker which has thus been made is described, e.g., in the Austrian patent specilication No. 218,090.
  • this loudspeaker at least the diaphragm frame is made by injection molding and is secured to the magnet system by the material which has penetrated through openings in the adjacent part of the magnet system, said material forming a sleevelike extension, which ensure-s the centric position of the iron core and of the air gap.
  • a plurality of other dynamic sound transducers have been disclosed, which comprise also fillers, preferably of plastic, which serve for connecting the parts of the magnet system and which lill the entire interior of the transducer and may form, together with the diaphragm frame, a unit made in one operation.
  • the transducer according to the invention does not have these disadvantages. Only a minimum amount of plastic or the like is used for its manufacture.
  • the transducer according to the invention is extremely robust. This is of special signilicance particularly for microphones. All these advantages do not involve a sacrifice of quality, which is even increased by the structure according to the invention.
  • the invention relates particularly to electro-acoustic transducers which comprise a magnet system having an l annular air gap and including a permanent magnet, which is axially or concentrically disposed, and a body, made preferably by an injection-molding or pressure-casting process from a metal which liows under pressure or from a plastic, particularly from a thermoplastic material,
  • the transducer according to the invention is characterized in that the injectionmolded or pressure-cast material fills entirely at least one free space provided in the magnet system in or around a core member preferably formed by said permanent magnet and the magnet system is surrounded by the same material also on the outside and the resulting integral body has extensions in the shape of discs, rings or the 3,342,953 Patented Sept. 19, 1967 ,Ice
  • the core member of a magnetic circuit defines at least two spaces in the magnetic circuit and at least one of said spaces is substantially free of said injection-molded or pressure-cast material. This may be effected by injection-molding or pressure-casting said material to surround said magnetic circuit and to lill only one of said spaces so as to hold said parts together as a unit.
  • the extensions in the form of discs, rings or of other formations on the integral body are provided with register marks, fitting pins or the like.
  • Another advantage afforded by the invention resides in that only those surfaces must be machined which are contiguous and through which the magnetic flux is transmitted, as well as the surfaces defining the annular air gap, of course, whereas all other surfaces do not require machining because they are coated or covered or the cavities defined by them are filled.
  • the invention includes also the apparatus for manufacturing the transducer according to the invention.
  • This apparatus consists essentially of a at base and a substantially pot-shaped top.
  • the plane of division between the top and base may lie approximately in the plane of the front pole piece.
  • FIG. 1 is a transverse sectional view showing a dynamic microphone embodying the invention
  • FIG. 2 in a sectional view showing the device for manufacturing the transducer.
  • FIG. 1 is a sectional view showing an electrodynamic microphone according to the invention. It comprises a permanent magnet 1, which has in this case an axial through bore, through which the rear face of the diaphragm can also be exposed to sound. In a loudspeaker, such a bore is only required for venting the space behind the diaphragm if the latter forms a'closed surface.
  • the substantially cylindrical permanent magnet 1 is adjoined at one end by the front pole piece 2 and on the other end by the rear pole piece 4.
  • the magnetic circuit is closed by the pot-shaped member 3 and the air gap 5, in which the coil 6 is movably arranged.
  • the rearpole piece 4 has at least one bore 7, through which the filler material can enter into the cavity 8 surrounding the permanent magnet 1.
  • the openings 27 are formed by the resilient cores 26 shown in FIG. 2.
  • a rimmed disc-shaped extension 9 provided in the plane of the front pole piece 2 has a rim portion 12 for the attachment of an outer potand has another rim portion 13, which together with the top surface of the liange 9 forms a dish, which receives the diaphragm 14 with its stilfening rings 15 and the protective cover 16 consisting preferably of plastic.
  • the protruding rim portion 13a is partly or entirely beaded over by hot-forming, as is shown on the right in FIG. 1.
  • the outer pot 11 is not intended in general to provide for a protection of the microphone because such a protection would not be required for a. transducer embodying the invention.
  • the outer pot 11 is provided for acoustic purposes in order to enable the formation of an acoustic impedance element required for modifying the properties of the microphone.
  • the outer pot 11 may form an essential part of the housing.
  • the fiange 9 is formed with one or more bores 18, behind which damping material 19 may be secured to provide a frictional acoustic resistance.
  • One or two of these bores may serve for the passage of the lead wires 20 to the moving coil.
  • the neck 28 may extend through the outer pot 11 to vent the thin or shallow air chambers behind the diaphragm so as to give the microphone a cardioid directional characteristic.
  • FIG. 2 is a sectional View showing an apparatus for manufacturing the transducer according to the invention. The representation is only diagrammatic and nonessential details have been omitted.
  • the apparatus consists essentially of a mold for injection-molding or casting, comprising a base 21 and a top 22.
  • the mold base is substantially flat and formed only with few recesses, for instance, for fitting pins 23 and for the mushroom-shaped portion 24, which is the assembled microphone defines the thin air chamber behind the diaphragm and holds the front pole piece 2 in centric position.
  • the recess for the mushroom-shaped portion 24 is bordered by a circular ring member 25, which ensures that the space for the air gap is left free and which is also required for centering the permanent magnet 1, the platelike pole piece 2 and the pot-shaped member 3.
  • the microphone shown in the apparatus has an omnidirectional rather than a unidirectional pattern.
  • the diaphragm is not exposed to sound from the rear of the transducer.
  • the bore in the permanent magnet 1 may be entirely filled with filler material and the cavity 8 around the permanet magnet may be utilized for acoustic purposes.
  • the mold top 22 is formed with the filling opening 28. Because the mold is not closely contiguous with the systern, the filling mass encloses the entire system also on the outside and leaves free only those portions to which other parts of the transducer, such as the diaphragm and its holder and, if desired, the diaphragm frame of loudspeakers, are secured. Alternatively, the loudspeaker frame may be made in a known manner simultaneously with the envelope of filler of the magnet system.
  • the front pole piece 2 is first placed onto the mold base and the magnet 1 is inserted.
  • the mold having the ring 25 which provides for the air gap thus determines at the same time the position of the essential parts of the magnet system because this ring 25 determines also the final position of the pot-shaped member 3.
  • the entire system is now assembled in correct position.
  • the mold top 22 is applied, which is obviously provided with fitting surfaces or fitting pins interengaging with the base to hold the two parts in the correct relative position.
  • resilient pins 26 force the two pole pieces against the magnet 1 so that the same is in snug engagement with the front pole piece 2 and the inside surface of the rear pole piece 4.
  • this mode of connection has the special advantage in electro-acoustic transducers that lall surfaces which do not constitute fitthe filler material provides nevertheless a smooth, attractive surface, which may be additionally provided with various projections, extensions or the like for any desired purpose so that, for instance, one and the same transducer may be incorporated in housings of different shapes without need for making a new mold.
  • the covering made preferably from thermoplastic material protects the entire system to a high degree from climatic infiuences.
  • the invention relates also to the novel magnet system units for electro-acoustic transducers and to processes for the manufacture of such units.
  • a magnetic system including an axially elongated annular permanent magnet, a pair of annular pole pieces having substantially flat portions engaged with the respective axially opposite ends of said annular permanent magnet and defining therewith an axial passage, and a substantially cylindrical magnetic yoke embracing said permanent magnet and said pole pieces and having one end engaging the radially outer periphery of one pole piece and having a radially inwardly extending portion at its opposite end radially spaced from the radially outer periphery of the other pole piece to define an annular air gap coaxial with said axial passage; a moving coil positioned in and displaceable axially of the air gap; and a body of moldable material at least partially filling said axial passage and extending axially outwardly of said pole pieces and radially over at least a portion of the outer surfaces thereof, said body of material extending completely over the outer surface of said one pole piece and laterally over the entire outer surface of said substantially cylindrical magnetic yoke
  • said one pole piece being cup-shaped and including a cylindrical rim having a radially outer surface engaged with the radially inner surface of said magnetic yoke.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Manufacturing & Machinery (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
US315584A 1962-12-13 1963-10-11 Electro-acoustic transducer Expired - Lifetime US3342953A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT974362A AT236474B (de) 1962-12-13 1962-12-13 Elektroakustischer Wandler und Vorrichtung zu seiner Herstellung

Publications (1)

Publication Number Publication Date
US3342953A true US3342953A (en) 1967-09-19

Family

ID=3616872

Family Applications (1)

Application Number Title Priority Date Filing Date
US315584A Expired - Lifetime US3342953A (en) 1962-12-13 1963-10-11 Electro-acoustic transducer

Country Status (10)

Country Link
US (1) US3342953A (de)
AT (1) AT236474B (de)
BE (1) BE641006A (de)
CH (2) CH418401A (de)
DE (3) DE1224366C2 (de)
ES (1) ES294434A1 (de)
FR (1) FR1377088A (de)
GB (1) GB1065454A (de)
NL (2) NL143786B (de)
SE (1) SE321957B (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3434205A (en) * 1962-10-01 1969-03-25 Electro Voice Method of making electroacoustical devices
US3581015A (en) * 1966-12-28 1971-05-25 Aiwa Co Dynamic microphone
US4418247A (en) * 1980-05-23 1983-11-29 International Standard Electric Corporation Electrodynamic transducer
US4672675A (en) * 1985-08-19 1987-06-09 International Jensen Incorporated Multiple speaker loudspeaker with conductive bridge
US20040022406A1 (en) * 2002-05-02 2004-02-05 Hutt Steven W. Magnet arrangement for loudspeaker

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1295657B (de) * 1967-07-26 1969-05-22 Krone Kg Elektrodynamische Hoerkapsel
FR2083672B1 (de) * 1970-03-31 1973-10-19 Senzaki Seisakusho Kk
GB2082020B (en) * 1980-06-30 1985-05-30 Pioneer Electronic Corp Ear speaker
DE3033631A1 (de) * 1980-09-06 1982-04-29 Fried. Krupp Gmbh, 4300 Essen Hoererkapsel fuer einen fernsprechapparat und verfahren zu ihrer herstellung
GB2113503B (en) * 1981-12-30 1985-05-09 Plessey Co Plc Electro-acoustic transducers
DE4007678A1 (de) * 1990-03-10 1991-09-12 Lehner Fernsprech Signal Dynamischer, elektroakustischer wandler
DE19816060A1 (de) * 1998-04-09 1999-11-18 Bosch Gmbh Robert Lautsprecher
DE102009036337B4 (de) * 2009-08-06 2014-01-02 Robert Bösnecker Vorrichtung mit eingebetteter Membrane

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2400662A (en) * 1941-05-27 1946-05-21 Int Standard Electric Corp Telephone transmitter and receiver
US2566604A (en) * 1948-03-16 1951-09-04 William C Eaves Electrodynamic loud-speaker assembly
US2714134A (en) * 1951-02-27 1955-07-26 Martin L Touger Headset receiver
US2890297A (en) * 1956-10-10 1959-06-09 Dictograph Products Co Inc Transducer assembly
US3041601A (en) * 1959-10-08 1962-06-26 Electric Auto Lite Co Horn frame mounting means
US3141070A (en) * 1959-06-24 1964-07-14 Philips Corp Electrodynamic microphone

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1702070U (de) * 1955-04-27 1955-07-07 Max Grundig Dauermagnetsystem in topfform fuer dynamische lautsprecher.
DE1744859U (de) * 1956-10-24 1957-05-16 Deutsche Edelstahlwerke Ag Ringspaltmagnetsystem.
DE1774170U (de) * 1958-06-28 1958-09-18 Holmberg & Co Dynamischer schallwandler.
DE1797780U (de) * 1959-02-13 1959-10-15 Siemens Elektrogeraete Gmbh Lautsprecher.
DE1799329U (de) * 1959-09-10 1959-11-05 Deutsche Edelstahlwerke Ag Ringspaltdauermagnetsystem mit einer topfartigen abschirmung.
DE1847044U (de) * 1961-12-22 1962-02-22 Magnetfabrik Gewerkschaft Wind Lautsprecher-magnetsystem mit membrankorb.

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2400662A (en) * 1941-05-27 1946-05-21 Int Standard Electric Corp Telephone transmitter and receiver
US2566604A (en) * 1948-03-16 1951-09-04 William C Eaves Electrodynamic loud-speaker assembly
US2714134A (en) * 1951-02-27 1955-07-26 Martin L Touger Headset receiver
US2890297A (en) * 1956-10-10 1959-06-09 Dictograph Products Co Inc Transducer assembly
US3141070A (en) * 1959-06-24 1964-07-14 Philips Corp Electrodynamic microphone
US3041601A (en) * 1959-10-08 1962-06-26 Electric Auto Lite Co Horn frame mounting means

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3434205A (en) * 1962-10-01 1969-03-25 Electro Voice Method of making electroacoustical devices
US3581015A (en) * 1966-12-28 1971-05-25 Aiwa Co Dynamic microphone
US4418247A (en) * 1980-05-23 1983-11-29 International Standard Electric Corporation Electrodynamic transducer
US4672675A (en) * 1985-08-19 1987-06-09 International Jensen Incorporated Multiple speaker loudspeaker with conductive bridge
US20040022406A1 (en) * 2002-05-02 2004-02-05 Hutt Steven W. Magnet arrangement for loudspeaker
US7203332B2 (en) * 2002-05-02 2007-04-10 Harman International Industries, Incorporated Magnet arrangement for loudspeaker

Also Published As

Publication number Publication date
CH418401A (de) 1966-08-15
DE1243240C2 (de) 1974-05-09
NL301514A (de)
ES294434A1 (es) 1964-04-01
BE641006A (de) 1964-04-01
DE1224366C2 (de) 1974-03-21
SE321957B (de) 1970-03-23
CH452606A (de) 1968-03-15
DE1224366B (de) 1966-09-08
FR1377088A (fr) 1964-10-31
AT236474B (de) 1964-10-26
DE1243240B (de) 1967-06-29
NL143786B (nl) 1974-10-15
GB1065454A (en) 1967-04-12

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