US3867587A - Magnetic circuit for an electro-acoustic converter - Google Patents

Magnetic circuit for an electro-acoustic converter Download PDF

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Publication number
US3867587A
US3867587A US315970A US31597072A US3867587A US 3867587 A US3867587 A US 3867587A US 315970 A US315970 A US 315970A US 31597072 A US31597072 A US 31597072A US 3867587 A US3867587 A US 3867587A
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United States
Prior art keywords
magnetic
electro
magnetic circuit
voice coil
acoustic converter
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Expired - Lifetime
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US315970A
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English (en)
Inventor
Isao Yamamuro
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.)
Pioneer Corp
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Pioneer Electronic Corp
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Filing date
Publication date
Application filed by Pioneer Electronic Corp filed Critical Pioneer Electronic Corp
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; 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; ELECTRIC HEARING AIDS; 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
    • H04R2209/021—Reduction of eddy currents in the magnetic circuit of electrodynamic loudspeaker transducer

Definitions

  • FIG. la FIG. lb
  • FIG. Ic PRIOR ART PRIOR ART I FIG. Ic PRIOR ART FIG. 2' PIC-5.3 M NETICMY 7 9 5 7 INSULATING IIIA TL IIZE I086 8 I0 I? s 579 '1 4 ⁇ W4 4 I 3 2 I 2 I FIG; 4
  • This invention relates to a magnetic circuit for an electro-acoustic converter such as a speaker or a microphone.
  • the present invention has taken notice of the aforementioned problems and eliminates the distortion caused bythe magnetic circuit.
  • the primary object of the present invention is to provide a magnetic circuit for an electro-acoustic coverting device characterized in that a portion or all of the magnetic circuit elements defining the air gap have magnetically anisotropic characteristics, thereby increasing the magnetic resistance against magnetic flux caused by a voice coil and eliminating the reproduction of distortion caused by the magnetic non-linearity in the magnetic circuit.
  • Another object of the present invention is to provide a magnetic circuit for an electro-acoustic converter which includes an air gap defined by magnetic parts of magnetic material laminated with an insulating layer so as to have the magnetic anisotropy whereby the reproduction distortion caused by the inductance of the coil is sharply reduced.
  • Another object of the present invention is to provide a magnetic circuit for an electro-acoustic converter whereby an electro-acoustic converter having a high conversion efficiency may be manufactured without difficulty because the eddy current power loss is decreased and most of the magnetic flux is used effeciently.
  • FIGS. la-lc are vertical sections of conventional magnetic circuit portions for an electro-acoustic converter.
  • FIGS. 2 and3 are vertical sections of embodiments of a magnetic circuit in accordance with the present invention.
  • FIG. 4 is an enlarged fragmentary sectional view schematically illustrating directions of magnetic flux of a voice coil.
  • 1 is a yoke
  • 2 is a center pole fixed in the center of the yoke l
  • 3 is a ringshaped magnet
  • 4 is a plate fixed on the magnet 3
  • 5 is a voice coil cylinder
  • 6 is a voice coil.
  • the upper outside portion of the pole 2 and the inside portion of the plate 4 are respectively constructed with magnetic parts 7 and 8, made of a stack of layers of magnetically anisotropic material such as two directional silicon steel 9 interleaved with insulating layers 10 having comparatively higher magnetic resistance so as to have characteristics of magnetic anisotropy.
  • the easy magnetizing axis and hard magnetizing axis of the parts 7 and 8 are consequently directed at right angles and parallel to the voice coil 6.
  • the magnetic flux out of the magnet 3 returns to the same magnet 3 by way of the plate 4, the easy magnetizing axis of the magnetically anisotropic part 8, the air gap, the easy magnetizing axis of the magnetically anisotropic part 7, the center pole 2 and the yoke l.
  • the magnetic flux for driving the speaker passes the air gap through the same path as in the conventional magnetic circuit.
  • the total magnetic resistance of the magnetic circuit is slightly greater as compared with that of the conventional magnetic circuit, because the magnetic flux for driving the voice coil passes through the easy magnetizing axis of the magnetic anisotropic parts 7 and 8.
  • the magnetic flux caused by the voice coil 6 follows the path shown by dotted lines in FIG. 4, that is, the magnetic flux completes closed loops which pass along both of the hard magnetizing axes of the magnetically anisotropic parts 7 and 8.
  • the magnetic flux passing the magnetically anisotropic parts is limited because of the high magnetic resistance and the magnetic saturation brought about with the small magnetic flux. Consequently, the reproduction distortion due to the magnetic non-linearity of the magnetic circuit elements decreases greatly because of the weak mutual relation of the magnetic flux of the voice coil 6 and the magnetic circuit parts.
  • the resistance of the two directional silicon steel is higher than that of normal iron, silicon steel is useful for diminishing eddy current power loss caused by the magnetic flux of the voice coil in the magnetic circuit elements.
  • the insulating layers 10 not only act as magnetic resistance members, but are useful to decrease the eddy current power loss, and thus a speaker or a microphone having a high conversion efficiency may be produced without difficulty because the magnetic flux acts to good advantage. Further, the sheets of magnetically anisotropic material or normal magnetic material act as short rings, and thus the distortion is reduced even more.
  • the magnetic circuit of the present invention is composed of laminated magnetic parts which increase the magnetic resistance against the magnetic flux caused by a voice coil.
  • the sheets of the magnetically anisotropic material are oriented such that the direction of the easy magnetizing axis is the same as the magnetic flux for driving the speaker or the microphone within the air gap. Consequently, the reproduction distortion is drastically reduced. Since the insulating layers are between the sheets of the magnetic material, the eddy current power loss decreased, consequently a speaker or a microphone having high conversion efficiency may be manufactured.
  • An electro-acoustic converter comprising:
  • said plate means is a stack of layers of a magnetically anisotropic material interleaved with insulating layers.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
US315970A 1971-12-17 1972-12-18 Magnetic circuit for an electro-acoustic converter Expired - Lifetime US3867587A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP46102518A JPS5234212B2 (2) 1971-12-17 1971-12-17

Publications (1)

Publication Number Publication Date
US3867587A true US3867587A (en) 1975-02-18

Family

ID=14329559

Family Applications (1)

Application Number Title Priority Date Filing Date
US315970A Expired - Lifetime US3867587A (en) 1971-12-17 1972-12-18 Magnetic circuit for an electro-acoustic converter

Country Status (3)

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US (1) US3867587A (2)
JP (1) JPS5234212B2 (2)
DE (1) DE2261499B2 (2)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5381483A (en) * 1993-04-05 1995-01-10 Commonwealth Of Puerto Rico Minimal inductance electrodynamic transducer
WO1996012382A1 (en) * 1992-12-23 1996-04-25 Grodinsky Robert M Reduced distortion loudspeakers
WO2001006523A3 (en) * 1999-07-20 2001-07-19 New Transducers Ltd Magnet assembly
US6289106B1 (en) 1997-08-08 2001-09-11 Hong Long Industrial Co., Ltd. Cap and center pole apparatus and method of coupling
FR2836000A1 (fr) * 2002-02-13 2003-08-15 Harman Internat Moteur electrodynamique a bobine mobile notamment pour haut-parleur, haut-parleur et piece polaire adaptee
US20030190052A1 (en) * 1998-03-19 2003-10-09 Jbl Incorporated Shorting rings in dual-coil dual-gap loudspeaker drivers
US20030190051A1 (en) * 1998-07-21 2003-10-09 Williamson Clayton C. Full range loudspeaker
US20050135651A1 (en) * 2002-05-10 2005-06-23 Bo Hakansson Means at electromagnetic vibrator
US20060097583A1 (en) * 2002-09-21 2006-05-11 Dodd Mark A Electromechanical transducers
US20110007913A1 (en) * 2008-01-07 2011-01-13 Scanspeak A/S Magnet assembly for a loudspeaker
CN103503480A (zh) * 2012-01-20 2014-01-08 松下电器产业株式会社 扬声器用磁回路及使用该扬声器用磁回路的扬声器
US20220141592A1 (en) * 2019-02-28 2022-05-05 Purifi Aps Loudspeaker motor with improved linearity
US20240406637A1 (en) * 2022-04-28 2024-12-05 Audio-Technica Corporation Electroacoustic transducer

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6252362U (2) * 1985-09-20 1987-04-01
JPH0317455U (2) * 1989-06-30 1991-02-21
JP5449002B2 (ja) * 2010-04-21 2014-03-19 株式会社オーディオテクニカ 音響用動電型変換器
EP3982513B1 (en) * 2020-10-08 2022-12-14 Melexis Technologies NV Transmitter for power line communication

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1976874A (en) * 1932-11-09 1934-10-16 Brzeski Henryk Loud speaker
US2320402A (en) * 1940-09-30 1943-06-01 Rca Corp Loud-speaker
US3632904A (en) * 1970-03-24 1972-01-04 Paul Mauz Moving coil loudspeaker with eddy current suppression
US3665352A (en) * 1970-05-12 1972-05-23 Deutsche Edelstahlwerke Ag Permanent magnet system for a loudspeaker
US3783311A (en) * 1970-12-19 1974-01-01 Coral Audio Corp Magnetic device for use in acoustic apparatus

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1976874A (en) * 1932-11-09 1934-10-16 Brzeski Henryk Loud speaker
US2320402A (en) * 1940-09-30 1943-06-01 Rca Corp Loud-speaker
US3632904A (en) * 1970-03-24 1972-01-04 Paul Mauz Moving coil loudspeaker with eddy current suppression
US3665352A (en) * 1970-05-12 1972-05-23 Deutsche Edelstahlwerke Ag Permanent magnet system for a loudspeaker
US3783311A (en) * 1970-12-19 1974-01-01 Coral Audio Corp Magnetic device for use in acoustic apparatus

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996012382A1 (en) * 1992-12-23 1996-04-25 Grodinsky Robert M Reduced distortion loudspeakers
US5381483A (en) * 1993-04-05 1995-01-10 Commonwealth Of Puerto Rico Minimal inductance electrodynamic transducer
US6289106B1 (en) 1997-08-08 2001-09-11 Hong Long Industrial Co., Ltd. Cap and center pole apparatus and method of coupling
US6473515B2 (en) 1997-08-08 2002-10-29 Ching Tong Wong Cap and center pole apparatus and method of coupling
US6847726B2 (en) * 1998-03-19 2005-01-25 Harman International Industries, Incorporated Shorting rings in dual-coil dual-gap loudspeaker drivers
US20030190052A1 (en) * 1998-03-19 2003-10-09 Jbl Incorporated Shorting rings in dual-coil dual-gap loudspeaker drivers
US6768806B1 (en) * 1998-03-19 2004-07-27 Harman International Industries, Incorporated Shorting rings in dual-coil dual-gap loudspeaker drivers
US7167573B2 (en) 1998-07-21 2007-01-23 Harman International Industries, Incorporated Full range loudspeaker
US20030190051A1 (en) * 1998-07-21 2003-10-09 Williamson Clayton C. Full range loudspeaker
WO2001006523A3 (en) * 1999-07-20 2001-07-19 New Transducers Ltd Magnet assembly
US20050226457A1 (en) * 2002-02-13 2005-10-13 Gilles Milot Moving-coil electrodynamic motor for a loudspeaker, loudspeaker and pole piece
WO2003069953A1 (fr) * 2002-02-13 2003-08-21 Harman International Moteur electrodynamique a bobine mobile notamment pour haut-parleur, haut-parleur et piece polaire adaptee
FR2836000A1 (fr) * 2002-02-13 2003-08-15 Harman Internat Moteur electrodynamique a bobine mobile notamment pour haut-parleur, haut-parleur et piece polaire adaptee
US7283642B2 (en) * 2002-02-13 2007-10-16 Harman International Industries, Incorporated Moving-coil electrodynamic motor for a loudspeaker, loudspeaker and pole piece
US20050135651A1 (en) * 2002-05-10 2005-06-23 Bo Hakansson Means at electromagnetic vibrator
US7471801B2 (en) * 2002-05-10 2008-12-30 Osseofon Ab Device for the generation of or monitoring of vibrations
US20060097583A1 (en) * 2002-09-21 2006-05-11 Dodd Mark A Electromechanical transducers
US20110007913A1 (en) * 2008-01-07 2011-01-13 Scanspeak A/S Magnet assembly for a loudspeaker
CN103503480A (zh) * 2012-01-20 2014-01-08 松下电器产业株式会社 扬声器用磁回路及使用该扬声器用磁回路的扬声器
US20140056468A1 (en) * 2012-01-20 2014-02-27 Panasonic Corporation Magnetic circuit for loudspeaker and loudspeaker using the same
US20220141592A1 (en) * 2019-02-28 2022-05-05 Purifi Aps Loudspeaker motor with improved linearity
US11956612B2 (en) * 2019-02-28 2024-04-09 Purifi Aps Loudspeaker motor with improved linearity
US20240406637A1 (en) * 2022-04-28 2024-12-05 Audio-Technica Corporation Electroacoustic transducer
EP4472237A4 (en) * 2022-04-28 2025-04-30 Audio-Technica Corporation ELECTROACOUSTIC TRANSDUCER

Also Published As

Publication number Publication date
DE2261499A1 (de) 1973-06-28
JPS5234212B2 (2) 1977-09-02
JPS4868218A (2) 1973-09-18
DE2261499B2 (de) 1975-07-03

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