EP1072168B1 - Kurzschlussringe für lautsprecherantrieb mit doppelspulen und doppelspalten - Google Patents

Kurzschlussringe für lautsprecherantrieb mit doppelspulen und doppelspalten Download PDF

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Publication number
EP1072168B1
EP1072168B1 EP99913989A EP99913989A EP1072168B1 EP 1072168 B1 EP1072168 B1 EP 1072168B1 EP 99913989 A EP99913989 A EP 99913989A EP 99913989 A EP99913989 A EP 99913989A EP 1072168 B1 EP1072168 B1 EP 1072168B1
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EP
European Patent Office
Prior art keywords
magnetic
annular
pole piece
voice coil
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
EP99913989A
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English (en)
French (fr)
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EP1072168A4 (de
EP1072168A1 (de
Inventor
Douglas J. Button
Ralph E. Hyde
Alex V. Salvatti
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Harman Professional Inc
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JBL Inc
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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
    • H04R2209/022—Aspects regarding the stray flux internal or external to the magnetic circuit, e.g. shielding, shape of magnetic circuit, flux compensation coils
    • 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
    • H04R2209/041—Voice coil arrangements comprising more than one voice coil unit on the same bobbin

Definitions

  • the present invention relates to the field of electromagnetic transducers and actuators, and more particularly it relates to improvements in loudspeaker drivers of the type having dual voice coils axially located in corresponding dual annular magnetic air gaps on a common axis.
  • the present inventors have found that the dual-voice-coil dual-gap type offers advantages with regard to linearity, efficiency, available voice coil excursion, power compression, heat dissipation and maximum sound pressure output capability. Furthermore they have found that certain benefits of the dual-coil dual-gap approach can be further enhanced by introducing shorting rings in the region of the two magnetic gaps near the voice coils.
  • Japanese patent 61-137496 to Okada introduces a conductive annular plate in a speaker magnet structure to prevent burning of a voice coil and to prevent an eddy current giving adverse influences to a voice coil current.
  • U.S. patent 5,381,483 to Grau discloses a minimal inductance electrodynamic transducer having ferromagnetic shunting rings coated with a highly conductive material to increase the induced current carrying capacity of the transducer.
  • U.S. patent 3,830,986 to Yamamuro discloses a MAGNETIC CIRCUIT FOR AN ELECTRO-ACOUSTIC CONVERTER having an air gap formed of a magnetic material laminated with a conductive layer for acting as shorting rings to decrease the inductance of the voice coil.
  • Japanese patent WO 81/02501 discloses a MAGNETIC CIRCUIT FOR AN ELECTRO-MECHANICAL TRANSDUCER OF A DYNAMIC ELECTRICITY TYPE wherein compensating coils or conductors within the magnetic gaps are supplied with signal current to prevent disturbances in the magnetic field.
  • Japanese patent 198208 discloses an ELECTROMAGNETIC CONVERTER wherein a magnetic ring is located in the air gap so that it can be moved axially between a circumferential yoke and a center yoke to provide good conversion efficiency by using a hollow disk permanent magnet that is magnetized in different poles at the center and external circumference.
  • U.S. patent 3,783,311 to Sato et al discloses a MAGNETIC DEVICE FOR USE IN ACOUSTIC APPARATUS wherein a metallic member in a voice coil gap permits the lines of magnetic force to move substantially in one direction only, for distortion reduction.
  • Patents that disclose dual voice coil dual magnetic gap drivers/actuators include U.S. patents 4,612,592 to Frandsen , 5,231,336 to Van Namen , and French patent 1,180,456 to Kritter ; however these do not disclose the use of shorting rings.
  • U.S. patent 4,914,707 to Kato et al for a BALANCE VEHICULAR SPEAKER SYSTEM suggests attaching a shorting ring to a coil of a dual-coil dual-gap front speaker in a vehicle to decrease the high frequency impedance as an alternative to connecting a resistor in series with a rear speaker, for purposes of making the impedance of the rear speaker higher than that of the front one.
  • the International Patent Application WO 96/33592 A describes a dual coil drive with a multipurpose housing.
  • the present invention thus, provides a loudspeaker driver structure according to claim 1.
  • the shorting rings have no effect on a steady state magnetic field but act in opposition to any change in flux density or any displacement of the flux lines such as those that occur under the loading imposed when the voice coils are driven hard with audio frequency current.
  • the location of the shorting rings determines their effect: location close to a voice coil reduces the voice coil inductance, location entirely within the magnetic flux loop centerline favors reduction of second harmonic and higher order even harmonic distortion, a centered location on the flux loop centerline, i.e. centered in the magnetic gap, favors reduction of third harmonic and higher odd order harmonic distortion, while location outside the flux loop centerline but near the voice coil acts generally to reduce harmonic distortion.
  • a plurality of rings can be differently located so as to optimally suppress both even and odd order harmonic distortion and reduce the voice coil inductance.
  • FIGs. 1-12 are basic functional representations of a dualgap dual-voice-coil loudspeaker driver, shown in half crosssection with a voice coil assembly 10 carrying voice coils 10A and 10B suspended in a pair of magnetized air gaps formed from a permanent magnet M disposed between a first steel pole piece N, at the north pole of magnet M and a second steel pole S at the south pole of magnet M, and a yoke 12 which is made of magnetic material and which can be considered to define, in effect, a pair of pole pieces that would substantially mirror the articulated pole pieces N and S of magnet M and thus form the two magnetic gaps.
  • the magnetic system of the foregoing structure sets up a magnetic flux loop in the path shown as a dashed line, i.e. flux loop center line 14, which is typically centered within each magnetic gap and within each voice coil 10A and 10B.
  • Voice coil assembly 10 is constrained by well known spring suspension diaphragm structure (not shown) so that it travels axially, typically driving a conventional speaker cone diaphragm (not shown) in response to AC (alternating current) applied to coils 10A and 10B, in accordance with the well known Right Hand Rule of electro-magnetic mechanics and in the general manner of loudspeakers, the two coils being phase-connected accordingly.
  • the half cross-section shown in FIGs. 1-12 represents a coaxial loudspeaker motor structure that can have either of two basic configurations that are inverse of each other:
  • a common inherent shortcoming in loudspeakers is that the magnetic flux in the region of the voice coil(s) is subject to pattern deformation or modulation as a reaction to drive current in the voice coil(s); this in turn can distort the acoustic output as well as increase the inductance of the coil winding(s), altering the frequency response.
  • shorting/shunting rings of highly conductive metal such as copper in the vicinity of the magnetic air gap of conventional single coil drivers can provide benefits by acting to stabilize the magnetic flux against such perturbation from modulation due to voice coil current.
  • Such shorting rings have no effect on the flux pattern as long as it remains constant and stationary, however the rings react with an internal flow of current that opposes any change in the flux pattern such as would be caused by the drive current in the voice coils, thus the rings can substantially reduce distortion in the acoustic output.
  • a shorting ring located near a voice coil tends to reduce the inductance of the voice coil.
  • the present inventors in research directed to improvements in dual-gap dual-coil transducer drivers, have identified key locations and configurations for such shorting rings, particularly with regard to distortion reduction, and have developed such locations and configurations for reducing second and/or third harmonic distortion selectively.
  • FIGs. 1-3 show locations of tubular-shaped shorting rings Shat are located within the flux loop as defined by its center line 14 and that therefore act in a manner to reduce even order harmonic distortion including particularly second harmonic distortion in accordance with the present invention.
  • the tubular shorting ring 16A is located adjacent to permanent magnet M, essentially extending between the two pole pieces N and S in a location adjacent to voice coil assembly 10 and entirely within the flux loop defined by center line 14.
  • the tubular shorting ring 16B is embedded in a recessed region of yoke 12, essentially extends between the two yoke pole pieces in a location adjacent to voice coil assembly 10 and entirely within the flux loop defined by center line 14.
  • two rings are incorporated in a driver unit: ring 16A, as in FIG. 1 and ring 16B, as in FIG. 2 ; since both rings are located within the flux loop defined by center line 14, the even order harmonic distortion suppression is greater than in either FIG. 1 or FIG. 2 .
  • FIGs. 4 and 5 show locations of annular shorting rings 16D and 16E configured as disks that have an edge positioned close to the voice coils of assembly 10 and that, being located outside the flux loop center line 14, act generally to reduce harmonic distortion and reduce voice coil inductance in accordance with the present invention.
  • a first pair of shorting.rings 16C are located on the outer surfaces of pole pieces N and S respectively and a second pair of shorting rings 16D are located on each end of yoke 12, all having an edge in close proximity to the voice coils of assembly 10.
  • the shorting rings 16C and 16D are shaped as annular disks, i.e. flat washers, however, depending on the configuration, i.e. whether CL1 or CL2 is the central axis, the pair of shorting rings that are centered on the axis need not have a central hole and thus could be shaped simply as circular disks.
  • two shorting rings 16E are fitted in the outer corners of yoke 12, in close proximity to the voice coils of assembly 10, but outside the flux loop as defined by center line 14.
  • FIGs. 6 and 7 show configurations with shorting ring locations near the voice coils both inside and outside the flux loop as defined by center line 14, thus acting mainly to suppress second harmonics and higher order even harmonics and to reduce voice coil inductance.
  • two shorting rings 16F' are located in the inner corners of each of the magnet pole pieces N and S, within the flux loop and acting mainly on even order harmonics, while two rings 16F are located in the outer corners of the magnet pole pieces N and S and two rings 16E are located in the outer corners of the yoke, as in FIG. 5 , these four rings, being located outside the flux loop but close to the voice coils of assembly 10, will thus acting generally to reduce harmonic distortion and reduce the inductance of the voice coils.
  • FIG. 7 a total of eight rings are deployed; a pair of shorting rings 16G and 16G' embedded in each of the pole pieces N and S as shown, and two corresponding pairs of shorting rings 16H and 16H' embedded in corresponding locations in yoke 12, so that four of the rings are inside the flux loop and the other four are outside the flux loop.
  • FIGs. 8-10 show shorting rings located substantially centered on the flux loop center line 14: this is the optimal location for suppression of odd order harmonics, particularly third harmonics.
  • shorting rings 16J and 16K are embedded in a center location, one each in all four pole pieces defining the two magnetic gaps, substantially centered on the flux loop center line 14.
  • the total faces of poles N and S are configured with laminated shorting ring structures 16L, and corresponding laminated shorting ring structures 16H are embedded in the upper pole piece regions of yoke 12 adjacent the voice coils as shown.
  • These laminated shorting ring structures 16L and 16H consist of sheets of electrically conductive metal (typically copper or aluminum) interleaved with magnetic grade steel laminations.
  • FIG. 10 depicts essentially an unlaminated version of FIG. 9 : lower faces of pole pieces N and S are fitted with shorting rings 16P of tubular shape, and yoke 12 is fitted with embedded shorting rings 16Q of tubular shape, somewhat longer than rings 16P and thus extending inwardly from the outer corners past the voice coils of assembly 10, acting to lower the voice coil inductance as well as to reduce harmonic distortion optimally.
  • a single tubular shorting ring 16R extending full length of the magnet assembly including a surface layer added onto the faces of pole pieces N and S close to the voice coils, thus acting to reduce voice coil inductance as well as to reduce harmonic distortion.
  • FIG. 12 depicts essentially a version of FIG. 11 with the tubular shorting ring 16S deployed as a surface layer extending full length along the upper surface of yoke 12 including its pole regions, close to the voice coils, thus providing further reduction in voice coil inductance.
  • FIGs. 10-12 Alternative viable combinations of FIGs. 10-12 include: ring 16R ( FIG. 11 ) deployed in place of rings 16P in FIG. 10 ; ring 16S ( FIG. 12 ) deployed in place of rings 16Q in FIG. 10 ; ring 16S ( Fig. 12 ) deployed in yoke 12 in FIG. 11 .
  • Shorting rings are most effective in reducing harmonic distortion in the audio frequency range 200 to 2,000 Hertz.

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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)
  • Circuit For Audible Band Transducer (AREA)

Claims (4)

  1. Eine Lautsprechertreiberstruktur zum Antreiben einer Membran, um Klang zu erzeugen, die umfasst:
    eine erste und eine zweite Schwingspule (10A, 10B), die sich voneinander beabstandet Ende-zu-Ende auf einem rohrförmigen Schwingspulenkörper als Teil einer koaxialen Schwingspulenanordnung (10) befinden, die um eine vertikale Achse angeordnet ist, und die antreibbar mit der Membran verbunden sind und elastisch eingeschränkt sind, so dass sie lediglich in einer longitudinalen Richtung der Achse vibrieren können;
    ein erstes und ein zweites kreisförmiges Magnetpolstück, die als ein gekoppeltes Paar ausgebildet und angeordnet sind, das einen ersten kreisförmigen magnetischen Spalt ausbildet, der über einen vorbestimmten kreisförmigen Bereich der genannten ersten Schwingspule (10A) verläuft;
    ein drittes und ein viertes kreisförmiges Magnetpolstück, die als ein gekoppeltes Paar ausgebildet und angeordnet sind, das einen zweiten kreisförmigen magnetischen Spalt ausbildet, der über einen vorbestimmten kreisförmigen Bereich der genannten zweiten Schwingspule (10B) verläuft;
    einen Permanentmagneten, der einen ersten magnetischen Pol, der zu dem genannten ersten Polstück hin gerichtet ist, und einen zweiten magnetischen Pol, der zu dem genannten dritten Polstück hin gerichtet ist, besitzt;
    ein magnetisches Joch (12), das ein erstes Ende, das zu dem genannten zweiten Polstück hin gerichtet ist, besitzt und ein zweites Ende, das zu dem vierten Polstück hin gerichtet ist, besitzt, und das somit einen magnetischen Hauptpfad um eine Flussschleife zur Verfügung stellt, die der Reihe nach umfasst: (a) den genannten Magneten; (b) das genannte erste Polstück, das ein erstes Magnetpolstück bildet, (c) den ersten magnetischen Spalt, der über die erste Schwingspule verläuft, (d) das genannte zweite Polstück, das ein erstes Jochpolstück bildet, (e) das genannte Joch (12), (f) das genannte vierte Polstück, das ein zweites Jochpolstück bildet, (g) den genannten zweiten magnetischen Spalt, der über die genannte zweite Schwingspule verläuft, und (h) das genannte dritte Polstück, das das zweite Magnetpolstück bildet, wodurch die Flussschleife vollendet wird;
    gekennzeichnet durch
    einen ersten kreisförmigen Kurzschlussring (16A), der dem genannten Magneten benachbart, zwischen dem genannten Magneten und dem Schwingspulenkörper, angeordnet ist und sich im wesentlichen zwischen den zwei Magnetpolstücken erstreckt; und
    einen zweiten kreisförmigen Kurzschlussring (16B), der dem genannten Joch (12) benachbart, zwischen dem genannten Joch (12) und dem Schwingspulenkörper, angeordnet ist, und der sich im wesentlichen zwischen den Jochpolstücken erstreckt,
    wobei der erste kreisförmige Kurzschlussring (16A) und der zweite kreisförmige Kurzschlussring (16B) dazu ausgebildet und derart angeordnet sind, dass sie als eine kurzgeschlossene Wicklungswindung fungieren, die jeder Änderung in der Stärke der Flussschleife entgegenwirkt und jeder Verschiebung derselben entgegenwirkt, so dass, wann immer die genannten Schwingspulen (10A, 10B) mit Audiofrequenzstrom betrieben werden, so dass der Schwingspulenkörper dazu veranlasst wird, die Membran in Vibration zu versetzen, der genannte Ring dazu veranlasst wird, in einer Weise zu reagieren, dass er eine harmonische Störung in der akustischen Ausgabe des genannten Lautsprechers verringert.
  2. Die Lautsprechertreiberstruktur, wie sie in Anspruch 1 definiert ist, in der der erste und zweite kreisförmige Kurzschlussring (16A, 16B) aus einem hochleitfähigen Metall hergestellt sind, sie koaxial angeordnet sind und sich in gekoppelter Beziehung zu der Flussschleife befinden.
  3. Die Lautsprechertreiberstruktur, wie sie in Anspruch 1 oder 2 definiert ist, in der der erste und zweite kreisförmige Kurzschlussring (16A, 16B) vollständig innerhalb der magnetischen Flussschlaufe angeordnet sind, wie sie durch eine Mittellinie (14) derselben definiert ist, so dass sie in einer Weise fungieren, dass sie insbesondere eine harmonische Störung einer geraden Ordnung in der akustischen Ausgabe verringern.
  4. Die Lautsprechertreiberstruktur, wie sie in Anspruch 3 definiert ist, in der zumindest einer der genannten kreisförmigen Kurzschlussringe (16A, 16B) aus einem Stapel einzelner isolierter Laminate aus magnetischem Edelstahl hergestellt ist.
EP99913989A 1998-03-19 1999-03-19 Kurzschlussringe für lautsprecherantrieb mit doppelspulen und doppelspalten Expired - Lifetime EP1072168B1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US7862398P 1998-03-19 1998-03-19
US78623P 1998-03-19
PCT/US1999/006084 WO1999048329A1 (en) 1998-03-19 1999-03-19 Shorting rings in dual-coil dual-gap loudspeaker drivers

Publications (3)

Publication Number Publication Date
EP1072168A1 EP1072168A1 (de) 2001-01-31
EP1072168A4 EP1072168A4 (de) 2006-02-08
EP1072168B1 true EP1072168B1 (de) 2008-11-12

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EP (1) EP1072168B1 (de)
JP (1) JP3574403B2 (de)
CN (1) CN1152601C (de)
AT (1) ATE414395T1 (de)
AU (1) AU3194199A (de)
CA (1) CA2324394C (de)
DE (1) DE69939898D1 (de)
WO (1) WO1999048329A1 (de)

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US6774510B1 (en) * 2000-10-25 2004-08-10 Harman International Industries, Inc. Electromagnetic motor with flux stabilization ring, saturation tips, and radiator
JP2006527933A (ja) * 2003-06-18 2006-12-07 余姚温度メーター工場有限責任公司 非励振磁気回路による低インダクタンス電磁ドライバー
CN101202161B (zh) * 2007-10-24 2012-12-26 钱维忠 开合式电流互感器
CN102149036A (zh) * 2010-02-09 2011-08-10 美律实业股份有限公司 具有双音圈的扬声器
FR2971385B1 (fr) * 2011-02-08 2014-02-14 Renault Sa Dispositif de moteur magnetique de transducteur electrodynamique
EP2833648B1 (de) * 2013-08-01 2016-04-27 Harman International Industries, Inc. Elektrodynamischer Lautsprecher mit leitenden Elementen
CN107820174B (zh) * 2017-11-22 2020-03-17 重庆长安汽车股份有限公司 一种车载扬声器磁路结构
US11785392B2 (en) 2019-09-27 2023-10-10 Apple Inc. Dual function transducer
US11070920B2 (en) * 2019-09-27 2021-07-20 Apple Inc. Dual function transducer
CN116980800A (zh) * 2023-09-25 2023-10-31 苏州墨觉智能电子有限公司 一种磁路组件、骨导发声装置及骨导耳机

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US3632904A (en) * 1970-03-24 1972-01-04 Paul Mauz Moving coil loudspeaker with eddy current suppression
US3783311A (en) * 1970-12-19 1974-01-01 Coral Audio Corp Magnetic device for use in acoustic apparatus
JPS542647Y2 (de) * 1971-03-10 1979-02-05
JPS5235294B2 (de) * 1971-12-17 1977-09-08
JP2501948Y2 (ja) * 1985-09-02 1996-06-19 パイオニア株式会社 車載音響装置
WO1991005447A1 (en) * 1989-10-02 1991-04-18 Jbl, Incorporated Improved electrodynamic loudspeaker
US5381483A (en) * 1993-04-05 1995-01-10 Commonwealth Of Puerto Rico Minimal inductance electrodynamic transducer
DK54093D0 (da) * 1993-05-10 1993-05-10 Scan Speak As Hoejttaler
WO1996033592A1 (en) * 1995-04-18 1996-10-24 Harman International Industries, Inc. Dual coil drive with multipurpose housing

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EP1072168A4 (de) 2006-02-08
CA2324394A1 (en) 1999-09-23
CN1298622A (zh) 2001-06-06
JP3574403B2 (ja) 2004-10-06
ATE414395T1 (de) 2008-11-15
AU3194199A (en) 1999-10-11
DE69939898D1 (de) 2008-12-24
JP2002507873A (ja) 2002-03-12
EP1072168A1 (de) 2001-01-31
CN1152601C (zh) 2004-06-02
CA2324394C (en) 2006-02-07
WO1999048329A1 (en) 1999-09-23

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