US3922501A - Moving voice coil electro-acoustic converter with laminated magnetically anisotropic poles - Google Patents

Moving voice coil electro-acoustic converter with laminated magnetically anisotropic poles Download PDF

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Publication number
US3922501A
US3922501A US315962A US31596272A US3922501A US 3922501 A US3922501 A US 3922501A US 315962 A US315962 A US 315962A US 31596272 A US31596272 A US 31596272A US 3922501 A US3922501 A US 3922501A
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United States
Prior art keywords
voice coil
magnetic
magnetically anisotropic
center pole
acoustic converter
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Expired - Lifetime
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US315962A
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English (en)
Inventor
Isao Yamamuro
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Pioneer Corp
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Pioneer Electronic Corp
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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
    • 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
    • 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

  • 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 by the magnetic circuit.
  • the primary object of the present invention is to provide a magnetic circuit for an electro-acoustic converting device characterized in that a portion or all of the magnetic circuit elements defining an air gap are formed of a magnetic anisotropic material, thereby increasing the magnetic resis tance to magnetic flux caused by a voice coil and eliminating the reproduction distortion caused by a magnetic non-linearity of a magnetic circuit.
  • FIGS. -10 are views in vertical section, of conventional magnetic circuit portions for an electro-acoustic converter.
  • FIG. 2 is a view in vertical section, of one embodiment of a magnetic circuit in accordance with the present invention.
  • FIG. 3 is an enlarged fragmentary sectional view schematically illustrating directions of magnetic flux.
  • FIG. 4 is a diagram illustrating the current distortion characteristic of a speaker using a conventional magnetic circuit.
  • FIG. 5 is a diagram illustrating the current distortion characteristics of a speaker using the magnetic circuit according to the present invention.
  • FIG. 6 is a view in vertical section, of another embodiment of the present invention.
  • FIG. 7 is an enlarged sectional view of the additional embodiment.
  • 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 por tion of the pole 2 and the inside portion of the plate 4 are respectively constructed with parts 7 and 8 which are magnetically anisotropic, such as a two directional silicon steel.
  • the easy magnetizing axis and hard mag netizing axis of the parts 7 and 8 are respectively 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 ofthe magnetically anisotropic part 7, the center pole 5, and the yoke 1.
  • the magnetic flux for driving the speaker passes the air gap through the same route as in the conventional magnetic circuit.
  • the total magnetic resistance of the magnetic circuit is slightly increased 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 magnetically anisotropic parts 7 and 8.
  • the magnetic flux caused by the voice coil 6 follows the path shown by dotted lines in FIG. 3, that is, the magnetic flux completes closed loops which pass along both the hard magnetizing axes of the magnetically anisotropic parts 7 and 8.
  • the magnetic flux passing the magnetic 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 diminishes greatly because of the weak mutual relation of the magnetic flux of the voice coil 6 and the magnetic circuit parts.
  • the electrical resistance of the two directional silicon steel is higher than normal iron, the silicon steel is useful for diminishing eddy current power loss caused by the magnetic flux of the voice coil in the magnetic circuit elements.
  • FIG. 4 is a diagram illustrating current distortion characteristics of a speaker using a conventional magnetic circuit.
  • FIG. 5 is a diagram illustrating current distortion characteristics of the speaker using a magnetic circuit according to the present invention, in which the upper outside portion of the center pole 2 and the inside portion of the plate 4 are constructed with the two directional silicon steel which is magnetically anisotropic. Comparing these characteristic diagrams, it is seen that the second harmonic distortion A and the third harmonic distortion B in case of the present invention speaker diminishes greatly in comparison with the second and third harmonic distortion curves A and B of the conventional speaker.
  • the characteristic curve between I-ll of the second harmonic distortion curve A shown in FIG. shows a filter characteristic of a distortion detector, the true distortion component is scarcely included between the HI.
  • a por tion of the elements of the magnetic circuit are constructed with the magnetically anisotropic material.
  • the whole of the plate 4 and the upper part of the center pole 2 may be composed of the magnetically anisotropic material as shown in FIG. 6, or may be composed of parts which have magnetically anisotropic characteristics, which laminate sheets 9 of the normal magnetic material or the magnetically anisotropic material.
  • an insulated or conductive lamination 10 may be positioned between sheets of the normal magnetic material.
  • the insulated lamination 10 is used, the eddy current power loss decreases and the magnetic flux acts to good advantage, and thus an electro-acoustic converter having a high conversion efficiency may be manufactured without difficulty.
  • the lamination 10 is conductive, the conductive laminations act as short rings, and thus the distortion is reduced more than with only the magnetically anisotropic material.
  • the present invention is characterized in that a portion or all of the magnetic circuit sections which define the boundaries of an air gap have portions which are magnetically anisotropic, namely 4 the portion having high magnetic resistance against a magnetic flux of a voice coil and low magnetic resistance against a magnetic flux for driving a speaker.
  • the present invention may be applied to other electro-acoustic converters such as a microphone.
  • an electro-acoustic converter comprising:

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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)
US315962A 1971-12-17 1972-12-18 Moving voice coil electro-acoustic converter with laminated magnetically anisotropic poles Expired - Lifetime US3922501A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP46102517A JPS4868217A (zh) 1971-12-17 1971-12-17

Publications (1)

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US3922501A true US3922501A (en) 1975-11-25

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US315962A Expired - Lifetime US3922501A (en) 1971-12-17 1972-12-18 Moving voice coil electro-acoustic converter with laminated magnetically anisotropic poles

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US (1) US3922501A (zh)
JP (1) JPS4868217A (zh)
DE (1) DE2261500B2 (zh)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4289937A (en) * 1978-05-30 1981-09-15 Mitsubishi Denki Kabushiki Kaisha Speaker with fine grain ferromagnetic material on center pole or ring
US4827162A (en) * 1987-03-02 1989-05-02 Unisys Corp. Controlled drag for magnet actuator
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
WO2001006523A2 (en) * 1999-07-20 2001-01-25 New Transducers Limited Magnet assembly
US6289106B1 (en) 1997-08-08 2001-09-11 Hong Long Industrial Co., Ltd. Cap and center pole apparatus and method of coupling
US20020021050A1 (en) * 2000-08-21 2002-02-21 Shoji Fujisawa Slider unit with built-in moving-coil linear motor
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
US6653753B1 (en) * 1999-04-13 2003-11-25 Matsushita Electric Industrial Co., Ltd. Linear motor
US20040213430A1 (en) * 2003-04-25 2004-10-28 Stiles Enrique M. Laminated motor structure for electromagnetic transducer
US20060018503A1 (en) * 2004-07-22 2006-01-26 Nobuhiro Endo Speaker device, magnetic circuit for use in speaker device, and method of manufacturing magnetic circuit
GB2527533A (en) * 2014-06-24 2015-12-30 Amina Technologies Ltd Moving coil drive unit and audio drivers incorporating the same
CN107948802A (zh) * 2017-12-25 2018-04-20 厦门东声电子有限公司 一种受话器
US20220141592A1 (en) * 2019-02-28 2022-05-05 Purifi Aps Loudspeaker motor with improved linearity

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108460225B (zh) * 2018-03-21 2021-08-31 华北电力大学（保定） 一种各向异性金属薄板感应式磁声图像的仿真方法及系统

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
US3830986A (en) * 1971-12-17 1974-08-20 Pioneer Electronic Corp Magnetic circuit for an electro-acoustic converter

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
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
US3830986A (en) * 1971-12-17 1974-08-20 Pioneer Electronic Corp Magnetic circuit for an electro-acoustic converter

Cited By (30)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4289937A (en) * 1978-05-30 1981-09-15 Mitsubishi Denki Kabushiki Kaisha Speaker with fine grain ferromagnetic material on center pole or ring
US4827162A (en) * 1987-03-02 1989-05-02 Unisys Corp. Controlled drag for magnet actuator
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
US20030190052A1 (en) * 1998-03-19 2003-10-09 Jbl Incorporated Shorting rings in dual-coil dual-gap loudspeaker drivers
US6847726B2 (en) * 1998-03-19 2005-01-25 Harman International Industries, 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
US7071584B2 (en) 1999-04-13 2006-07-04 Matsushita Electric Industrial Co., Ltd. Linear motor
US20040207272A1 (en) * 1999-04-13 2004-10-21 Matsushita Electric Industrial Co., Ltd. Linear motor
US6653753B1 (en) * 1999-04-13 2003-11-25 Matsushita Electric Industrial Co., Ltd. Linear motor
WO2001006523A3 (en) * 1999-07-20 2001-07-19 New Transducers Ltd Magnet assembly
WO2001006523A2 (en) * 1999-07-20 2001-01-25 New Transducers Limited Magnet assembly
US20020021050A1 (en) * 2000-08-21 2002-02-21 Shoji Fujisawa Slider unit with built-in moving-coil linear motor
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
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
US7283642B2 (en) 2002-02-13 2007-10-16 Harman International Industries, Incorporated Moving-coil electrodynamic motor for a loudspeaker, loudspeaker and pole piece
US20040213430A1 (en) * 2003-04-25 2004-10-28 Stiles Enrique M. Laminated motor structure for electromagnetic transducer
US7457429B2 (en) * 2003-04-25 2008-11-25 Step Technologies Inc. Laminated motor structure for electromagnetic transducer
US20060018503A1 (en) * 2004-07-22 2006-01-26 Nobuhiro Endo Speaker device, magnetic circuit for use in speaker device, and method of manufacturing magnetic circuit
GB2527533A (en) * 2014-06-24 2015-12-30 Amina Technologies Ltd Moving coil drive unit and audio drivers incorporating the same
GB2527533B (en) * 2014-06-24 2016-07-13 Amina Tech Ltd Moving coil drive unit and audio drivers incorporating the same
CN107948802A (zh) * 2017-12-25 2018-04-20 厦门东声电子有限公司 一种受话器
CN107948802B (zh) * 2017-12-25 2024-04-23 厦门东声电子有限公司 一种受话器
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

Also Published As

Publication number Publication date
DE2261500A1 (de) 1973-06-28
DE2261500B2 (de) 1975-07-03
JPS4868217A (zh) 1973-09-18

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