EP0013419A1 - Dynamic transducer comprising a voice coil in an air gap filled with a magnetic fluid - Google Patents

Dynamic transducer comprising a voice coil in an air gap filled with a magnetic fluid Download PDF

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Publication number
EP0013419A1
EP0013419A1 EP79105352A EP79105352A EP0013419A1 EP 0013419 A1 EP0013419 A1 EP 0013419A1 EP 79105352 A EP79105352 A EP 79105352A EP 79105352 A EP79105352 A EP 79105352A EP 0013419 A1 EP0013419 A1 EP 0013419A1
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EP
European Patent Office
Prior art keywords
voice coil
membrane
magnetic
case
liquid
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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.)
Ceased
Application number
EP79105352A
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German (de)
French (fr)
Inventor
Karl-Heinz Dipl.-Phys. Thiele
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Licentia Patent Verwaltungs GmbH
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Licentia Patent Verwaltungs GmbH
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Publication of EP0013419A1 publication Critical patent/EP0013419A1/en
Ceased 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
    • H04R9/025—Magnetic circuit
    • H04R9/027—Air gaps using a magnetic fluid

Definitions

  • Dynamic loudspeakers are known (Instr. A. Control Syst. 48 (1975) 10, pages 41-44), in which the space of the magnetic pole body, referred to as "air gap", in which the voice coil of the dynamic system can be moved, contains a magnetic liquid is filled.
  • the magnetic liquid is held in the air gap by the permanent magnetic field of the magnetic pole body. It is intended to improve the acoustic properties, in particular the distortion factor and the phase profile of the loudspeaker system.
  • the manufacture of the loudspeaker is also simplified, since manufacturing variations in the dimensions of the air gap have less of an effect.
  • the "air gap” receives properties from the filling that approximate the properties of the magnetic poles. As a result, the air gap is reduced to the value zero.
  • the magnetic liquid has a much higher thermal conductivity than air, so that the heat transfer resistance from the voice coil winding to the magnetic pole body is reduced. This increases the maximum permissible input power based on the same maximum temperatures of the voice coil.
  • the invention has for its object to further improve a dynamic converter of the type described.
  • the aim is to ensure that the properties of the converter do not change over a long period of time.
  • the invention is based on the following finding:
  • the magnetic liquid in the air gap of the magnet system is heated by the voice coil.
  • the magnetic liquid evaporates. Even if the magnetic liquid with low partial pressure is used for the liquid carrier, partial evaporation of the carrier liquid can occur over time.
  • the arrangement according to the invention can. establish a balance between the degree of saturation of the air and the partial pressure of the carrier liquid in the gas-tight space which is located around the magnetic liquid. So that no gas molecules can escape from the closed room, the materials surrounding the room should meet the requirement that the pore size in the material is smaller than the so-called free length of the vaporized molecules of the carrier liquid at the operating temperature of the speaker system. If the pore size is orders of magnitude smaller than the free path length of the molecules, the gas can be prevented from escaping.
  • the evaporated carrier liquid is then opposed to a sufficiently high flow resistance.
  • the magnetic body is composed of a magnetic base 6 with a pole core 11, an annular permanent magnet 5 and an upper pole plate 4.
  • the pole plate 4 surrounds the pole core 11 and forms an air gap 3, in which the voice coil 2 is movably arranged.
  • the free space between the voice coil 2 and the pole plate 4 on the one hand and the voice coil 2 and the pole core 11 on the other hand is filled with a magnetic liquid 3 over the entire circumference of the voice coil. This creates a closed cavity 12 below the voice coil 2.
  • the pole core 11 has a central bore 8, which leads from the air space below the spherical cap 1 to a resonance chamber located below the magnetic base 6 and formed by a housing 7. This arrangement is used for frequency correction of the speaker system.
  • the cavity 12 formed below the voice coil 3 is connected by a bore 10 to the central bore 8 of the pole core 11, so that a pressure equalization from the cavity 12 to the much larger air space 7, 8 can take place.
  • a bore 9 which is indicated by dashed lines in FIG. 1, can also be provided in the magnetic base 6.
  • the material from which the spherical cap membrane 1 and the housing 7 are made is selected so that the gas enclosed by these parts cannot escape or diffuse through the material. Since the magnet base 6, the magnet 5 and the pole plate 4 are firmly glued to one another over their entire contact surface, there is no risk that the gas will escape.
  • FIG. 2 shows a further exemplary embodiment of the invention using the example of a cone loudspeaker.
  • This loudspeaker is constructed similarly to the loudspeaker according to FIG. 1 from a membrane 13, a voice coil 19, a pole plate 16, a permanent magnet 17, a magnetic base 18 with a pole core 24, and a magnetic liquid 20.
  • the much larger membrane 13, the external fastening is not shown for reasons of space, is centered in the lower area by a centering membrane 14 so that the voice coil does not come into contact with the pole core 24 or the pole plate 16.
  • the centric membrane 14 is fastened on the outside to a ring 15 arranged on the pole plate 16.
  • a spherical cap 23 is glued into the center of the cone membrane 13.
  • a bore 21 is provided from the cavity 22 below the voice coil 19 for pressure equalization to the air space 25 below the centering membrane 14.
  • the cavity 27 located under the calotte 23 is connected to the cavity 25 formed below the centering membrane by openings 26 in the support of the voice coil 19.
  • the gas-filled cavities 22, 25 and 27 are therefore connected to one another through openings to compensate for pressure fluctuations in the individual cavities.
  • the gas located in the cavities 22, 25 and 27 borders on the magnetic liquid 20.
  • a gas-tight material for the centering membrane 14 and the spherical cap 23 it is achieved that gas molecules of the carrier liquid of the magnetic liquid 20 cannot escape.
  • the air in the cavities 22, 25 and 27 is saturated with gas molecules of the carrier liquid, no further carrier liquid evaporates.
  • the quantity and the composition of the magnetic liquid are kept constant in this way. This ensures that the quality of the system remains unchanged over a long period of time.
  • the materials for the membrane 1 in FIG. 1 and the centering membrane 14 in FIG. 2 are, for example
  • Plastics such as PVC, metal foils e.g. Aluminum foils, or sealed paper in question.
  • the dome 23 in Fig. 2 is advantageously made of a metal, e.g. Aluminum.

Abstract

Bei einem dynamischen Wandler mit magnetischer Flüssigkeit (20) im Luftspalt des Wandlers werden an die magnetische Flüssigkeit angrenzende Hohlräume (22,25,27) zur Verm eidung der Verdunstung der Trägerflüssigkeit der magnetischen Flüssigkeit gasdicht verschlossen.In a dynamic transducer with magnetic fluid (20) in the air gap of the transducer, cavities (22, 25, 27) adjacent to the magnetic fluid are closed in a gas-tight manner in order to avoid evaporation of the carrier fluid of the magnetic fluid.

Description

Es sind dynamische Lautsprecher bekannt (Instr. A. Control Syst. 48 (1975) 10 Seite 41-44), bei denen der mit "Luftspalt" bezeichnete Raum des Magnetpolkörpers, in dem die Schwingspule des dynamischen Systems bewegbar ist, mit einer magnetischen Flüssigkeit gefüllt ist. Die magnntische Flüssigkeit wird von dem permanenten Magnetfeld des Magnetpolkörpers im Luftspalt festgehalten. Sie soll eine Verbesserung der akustischen Eigenschaften, insbesondere des Klirrfaktors und des Phasenverlaufes des Lautsprechersystems hervorrufen. Auch wird die Fertigung des Lautsprechers vereinfacht, da Fertigungsstreuungen der Abmessungen des Luftspaltes sich weniger stark auswirken. Der "Luftspalt" erhält durch die Füllung Eigenschaften, die den Eigenschalften der Magnetpole angenähert sind. Es wird dadurch sinngemäß der Luftspalt auf den Wert Null verkleinert.Dynamic loudspeakers are known (Instr. A. Control Syst. 48 (1975) 10, pages 41-44), in which the space of the magnetic pole body, referred to as "air gap", in which the voice coil of the dynamic system can be moved, contains a magnetic liquid is filled. The magnetic liquid is held in the air gap by the permanent magnetic field of the magnetic pole body. It is intended to improve the acoustic properties, in particular the distortion factor and the phase profile of the loudspeaker system. The manufacture of the loudspeaker is also simplified, since manufacturing variations in the dimensions of the air gap have less of an effect. The "air gap" receives properties from the filling that approximate the properties of the magnetic poles. As a result, the air gap is reduced to the value zero.

Ein weiterer wesentlicher Vorteil gegenüber dynamischen Systemen mit ungefülltem Luftspalt ist das verbesserte Wärmeverhalten. Die magnetische Flüssigkeit besitzt im Vergleich zur Luft eine sehr viel höhere Wärmeleitfähigkeit, so daß der Wärmeübergangswiderstand von der Schwingspulenwicklung zum Magnetpolkörper verringert ist. Dadurch ist die maximal zulässige Eingangsleistung unter Zugrundelegung gleicher Maximaltemperaturen der Schwingspule erhöht.Another significant advantage over dynamic systems with an unfilled air gap is the improved thermal behavior. The magnetic liquid has a much higher thermal conductivity than air, so that the heat transfer resistance from the voice coil winding to the magnetic pole body is reduced. This increases the maximum permissible input power based on the same maximum temperatures of the voice coil.

Der Erfindung liegt die Aufgabe zugrunde, einen dynamischen Wandler der beschriebenen Art weiter zu verbessern. Insbesondere soll erreicht werden, daß die Eigenschaften des Wandlers sich üher einen langen Zeitraum nicht verändern.The invention has for its object to further improve a dynamic converter of the type described. In particular, the aim is to ensure that the properties of the converter do not change over a long period of time.

Diese Aufgabe wird durch die im Anspruch 1 angegebene Erfindung gelöst. In den Unteransprüchen sind vorteilhafte Ausführungsbeispiele der Erfindung angegeben.This object is achieved by the invention specified in claim 1. Advantageous exemplary embodiments of the invention are specified in the subclaims.

Der Erfindung liegt die folgende Erkenntnis zugrunde: Die magnetische Flüssigkeit in dem Luftspalt des Magnetsystems wird von der Schwingspule aufgeheizt. Begünstigt durch die Wärme findet eine Verdunstung der magnetischen Flüssigkeit statt. Selbst wenn für den Flüssigkeitsträger der magnetischen Flüssigkeit mit niedrigem Partialdruck verwendet wird, kann sich im Zeitverlauf eine teilweise Verdunstung der Trägerflüssigkeit einstellen. Bei der erfindungsgemäßen Anordnung kann sich. in dem gasdichten Raum, der sich um die magnetische Flüssigkeit herum befindet, ein Gleichgewicht zwischen dem Sättigungsgrad der Luft und dem Partialdruck der Trägerflüssigkeit aufbauen. Damit keine Gasmoleküle aus dem abgeschlossenen Raum entweichen können, sollten die den Raum umschlließenden Materialien die Forderung erfüllen, daß die Porengröße im Werkstoff kleiner ist als die sogenannte frei Veglänge der verdampften Moleküle der Trägerflüssigkeit beider Betriebstemperatur des Lautsprechersystems. Wenn die Porengröße um Größenordnungen kleiner ist als die freie Weglänge der Moleküle, so kann ein Entweichen des Gases ausgeschlossen werden. Der verdampftenTrägerflüssigkeit wird dann ein hinreichend hoher .Strömungswiderstand entgegengesetzt.The invention is based on the following finding: The magnetic liquid in the air gap of the magnet system is heated by the voice coil. Favored by the heat, the magnetic liquid evaporates. Even if the magnetic liquid with low partial pressure is used for the liquid carrier, partial evaporation of the carrier liquid can occur over time. In the arrangement according to the invention can. establish a balance between the degree of saturation of the air and the partial pressure of the carrier liquid in the gas-tight space which is located around the magnetic liquid. So that no gas molecules can escape from the closed room, the materials surrounding the room should meet the requirement that the pore size in the material is smaller than the so-called free length of the vaporized molecules of the carrier liquid at the operating temperature of the speaker system. If the pore size is orders of magnitude smaller than the free path length of the molecules, the gas can be prevented from escaping. The evaporated carrier liquid is then opposed to a sufficiently high flow resistance.

Die Erfindung wird im fol genden anhand von in der Zeichnung dargestellten Ausführungsbeispielen erläutert. Es zeigen:

  • Fig. 1 einen Hochtonkalottenlautsprecher und
  • Fig. 2 einen Konuslautsprecher mit den erfindungsgemäßen Merkmalen.
The invention is explained in the fol lowing with reference to embodiments shown in the drawing. Show it:
  • Fig. 1 a tweeter speaker and
  • Fig. 2 shows a cone speaker with the features of the invention.

In Fig. 1 ist ein elektrodynamischer Kalotten-Hochtonlautsprecher mit einer Kalotten-Membran 1 und einer die Membran 1 antreibenden Schwingspule 2 dargestellt. Der Magnetkörper ist zusammengesetzt aus einem Magnetgrund 6 mit einem Polkern 11, einem ringförmigen Permanent-Magneten 5 und einer oberen Polplatte 4. Die Polplatte 4 umg-iht den Polkern 11 und bildet einen Luftspalt 3, in dem die Schwingspule 2 bewegbar angeordnet ist. Der freie Zwischenraum zwischen der Schwingspule 2 und der Polplatte 4 einerseits und der Schwingspule 2 und dem Polkern 11 andererseits ist über den ganzen Umfang der Schwingspule mit einer magnetischen Flüssigkeit 3 gefüllt. Dadurch entsteht unterhalb der Schwingspule 2 ein abgeschlossener Hohlraum 12. Der Polkern 11 weist eine zentrale Bohrung 8 auf, die von dem Luftraum unterhalb der Kalotte 1 zu einem unterhalb des Magnetgrundes 6 liegenden und durch ein Gehäuse 7 gebildeten Resonanzraum führt. Diese Anordnung dient zur Frequenzkorrektur des Lautsprechersystems.1 shows an electrodynamic dome tweeter with a dome membrane 1 and a voice coil 2 driving the membrane 1. The magnetic body is composed of a magnetic base 6 with a pole core 11, an annular permanent magnet 5 and an upper pole plate 4. The pole plate 4 surrounds the pole core 11 and forms an air gap 3, in which the voice coil 2 is movably arranged. The free space between the voice coil 2 and the pole plate 4 on the one hand and the voice coil 2 and the pole core 11 on the other hand is filled with a magnetic liquid 3 over the entire circumference of the voice coil. This creates a closed cavity 12 below the voice coil 2. The pole core 11 has a central bore 8, which leads from the air space below the spherical cap 1 to a resonance chamber located below the magnetic base 6 and formed by a housing 7. This arrangement is used for frequency correction of the speaker system.

Der unterhalb der Schwingspule 3 gebildete Hohlraum 12 ist durch eine Bohrung 10 mit der zentralen Bohrung 8 des Polkernes 11 verbunden, so daß ein Druckausgleich von dem Hohlraum 12 zu dem wesentlich größeren Luftraum 7, 8 stattfinden kann. Statt der Bohrung 10 kann auch im Magnetgrund 6 eine Bohrung 9, die in Fig. 1 gestrichelt angedeutet ist, vorgesehen werden.The cavity 12 formed below the voice coil 3 is connected by a bore 10 to the central bore 8 of the pole core 11, so that a pressure equalization from the cavity 12 to the much larger air space 7, 8 can take place. Instead of the bore 10, a bore 9, which is indicated by dashed lines in FIG. 1, can also be provided in the magnetic base 6.

Das Material, aus dem die Kalottenmembran 1 und das Gehäuse 7 hergestellt sind, ist so gewählt, daß das von diesen Teilen umschlossene Gas nicht durch das Material austreten oder diffundieren kann. Da der Magnetgrund 6, der Magnet 5 und die Polplatte 4 fest über ihre ganze Berührungsfläche fest miteinander verklebt sind, besteht hier nicht die Gefahr, daß das Gas entweicht.The material from which the spherical cap membrane 1 and the housing 7 are made is selected so that the gas enclosed by these parts cannot escape or diffuse through the material. Since the magnet base 6, the magnet 5 and the pole plate 4 are firmly glued to one another over their entire contact surface, there is no risk that the gas will escape.

In Fig. 2 ist ein weiteres Ausfiihrungsbeispiel der Erfindung am Beispiel eines Konuslautsprechers dargestellt. Dieser Lautsprecher ist ähnlich wie der Lautsprecher gemäß Fig. 1 aufgebaut aus einer Membran 13, einer Schwingspule 19, einer Polplatte 16, einem Permanentmagneten 17, einem Magnetgrund 18 mit einem Polkern 24, und einer magnetischen Flüssigkeit 20. Die wesentlich größere Membran 13, deren äußere Befestigung aus Platzgründen nicht dargestellt ist, ist im unteren Bereich durch eine Zentriermemhran 14 zentriert, damit die Schwingspule nicht mit dem Polkern 24 bzw. der Polplatte 16 in Berührung kommt. Die Zentricrmembran 14 ist außen an einem auf der Polplattc 16 angeordneten Ring 15 befestigt. In das Zentrum der Konusmembran 13 ist eine Kalotte 23 eingeklebt Von dem Hohlraum 22 unterhalb der Schwingspule 19 ist zum Druckausgleich eine Bohrung 21 zu dem Luftraum 25 unterhalb der Zentriermembran 14 vorgesehen.2 shows a further exemplary embodiment of the invention using the example of a cone loudspeaker. This loudspeaker is constructed similarly to the loudspeaker according to FIG. 1 from a membrane 13, a voice coil 19, a pole plate 16, a permanent magnet 17, a magnetic base 18 with a pole core 24, and a magnetic liquid 20. The much larger membrane 13, the external fastening is not shown for reasons of space, is centered in the lower area by a centering membrane 14 so that the voice coil does not come into contact with the pole core 24 or the pole plate 16. The centric membrane 14 is fastened on the outside to a ring 15 arranged on the pole plate 16. A spherical cap 23 is glued into the center of the cone membrane 13. A bore 21 is provided from the cavity 22 below the voice coil 19 for pressure equalization to the air space 25 below the centering membrane 14.

Zu dem gleichen Zweck ist der unter der Kalotte 23 befindliche Holraum 27 durch Öffnungen 26 im Träger der Schwingspule 19 mit dem unterhalb der Zentriermembran gebildeten Hohlraum 25 verbunden. Die gasgefüllten Hohlräume 22, 25 und 27 sind also zum Ausgleich von Druckschwankungen in den einzelnen Hohlräumen miteinander durch Öffnungen verbunden.For the same purpose, the cavity 27 located under the calotte 23 is connected to the cavity 25 formed below the centering membrane by openings 26 in the support of the voice coil 19. The gas-filled cavities 22, 25 and 27 are therefore connected to one another through openings to compensate for pressure fluctuations in the individual cavities.

Das in den Hohlräumen 22, 25 und 27 befindliche Gas grenzt an die magnetische Flüssigkeit 20. Durch Verwendung eines gasdichten Materials für die Zentriermembran 14 und die Kalotte 23 wird erreicht, daß Gasmoleküle der Trägerflüssigkeit der magnetischen Flüssigkeit 20 nicht entweichen können. Wenn die Luft in den Hohlräumen 22, 25 und 27 mit Gasmolekülen der Trägerflüssigkeit gesättigt ist, verdunstet keine weitere Trägerflüssigkeit mehr. Die Menge und die Zusammensetzung der magnetischen Fliissigkeit wird auf diese Weiee konstant gehalten. Es ist damit gewährleistet, daß die Qualität des Systems über lange Zeit unverändert bleibt. Als Materialien für die Membran 1 in Fig. 1 und die Zentriermembran 14 in Fig. 2 kommen z.B.The gas located in the cavities 22, 25 and 27 borders on the magnetic liquid 20. By using a gas-tight material for the centering membrane 14 and the spherical cap 23, it is achieved that gas molecules of the carrier liquid of the magnetic liquid 20 cannot escape. When the air in the cavities 22, 25 and 27 is saturated with gas molecules of the carrier liquid, no further carrier liquid evaporates. The quantity and the composition of the magnetic liquid are kept constant in this way. This ensures that the quality of the system remains unchanged over a long period of time. The materials for the membrane 1 in FIG. 1 and the centering membrane 14 in FIG. 2 are, for example

Kunststoffe, wie PVC, Metallfolien, z.B. Aluminiumfolien, oder versiegeltes Papier in Frage. Die Kalotte 23 in Fig. 2 wird vorteilhaft aus einem Metall, z.B. Aluminium, hergestellt.Plastics such as PVC, metal foils e.g. Aluminum foils, or sealed paper in question. The dome 23 in Fig. 2 is advantageously made of a metal, e.g. Aluminum.

Claims (10)

1. Dynamischer elektroakustischer Wandler mit einem Magnetpolkörper und einer in einen Spalt des Magnethohlkörpers ragenden Schwingspule, bei dem in den Spalt zwischen der Schwingspule und dem Mangnetpolkörper wenigstens an einer Seite der Schwingspule eine magnetische Flüssigkeit gegeben ist, dadurch gekennzeichnet, daß der an die magnetische Flüssigkeit angrenzende Raum (22,25,27) derart gasdicht abgeschlossen ist, daß Moleküle der Trägerflüssigkeit der magnetischen Flüssigkeit nicht entweichen können.1. Dynamic electroacoustic transducer with a magnetic pole body and a voice coil protruding into a gap of the hollow magnetic body, in which a magnetic liquid is present in the gap between the voice coil and the magnetic pole body at least on one side of the voice coil, characterized in that the magnetic liquid adjacent space (22, 25, 27) is sealed in a gas-tight manner so that molecules of the carrier liquid of the magnetic liquid cannot escape. 2. Wandler nach Anspruch 1, dadurch gekennzeidhnet, daß für die den angrenzenden Raum einschließenden Bauteile (14,23) Materialien verwendet sind, die eine Porengröße aufweisen, die um Größenordnungen kleiner als die freie Weglänge der verdampften Moleküle der Trägerflüssigkeit der magnetischen Flüssigkeit ist.2. Transducer according to claim 1, characterized in that materials are used for the components (14, 23) enclosing the adjacent space, which have a pore size that is orders of magnitude smaller than the free path length of the vaporized molecules of the carrier liquid of the magnetic liquid. 3. Wandler nach Anspruch 1, dadurch gekennzeichnet, daß im Falle eines Lautsprechers die Membran (1) aus einem Kunststoff, z.B. PVC,hergestellt ist.3. Converter according to claim 1, characterized in that in the case of a speaker, the membrane (1) made of a plastic, e.g. PVC, is made. 4. Wandler nach Anspruch 1, dadurch gekennzeichnet, daß im Falle eines Lautsprechers die Membran aus Metall, z.B. Aluminium, hergestellt ist.4. Transducer according to claim 1, characterized in that in the case of a loudspeaker the membrane made of metal, e.g. Aluminum. 5. Wandler nach Anspruch 1, dadurch gekennzeichnet, daß im Falle eines Lautsprechers mit konzentrisch angeordneter Kalotte (1 bzw.23) die Kalotte (1 bzw. 23) aus einem Metallwerkstoff, z.B. Aluminium, hergestellt ist.5. Transducer according to claim 1, characterized in that in the case of a loudspeaker with a concentrically arranged dome (1 or 23), the dome (1 or 23) made of a metal material, e.g. Aluminum. 6. Wandler nach Anspruch 1, dadurch gekennzeichnet, daß die Kalotte aus Kunststoff, z.B. PVC, hergestellt ist.6. Transducer according to claim 1, characterized in that the calotte made of plastic, e.g. PVC, is made. 7. Wandler nach Anspruch 2, dadurch gekennzeichnet, daß im Falle eines Konuslautsprechers mit Zentriermembran (14) die Zentriermembran (14) aus versiegeltem Gewebe hergestellt ist.7. Converter according to claim 2, characterized in that in the case of a cone speaker with centering membrane (14), the centering membrane (14) is made of sealed fabric. 8. Wandler nach Anspruch 2, dadurch gekennzeichnet, daß im Falle eines Konuslautsprechers mit Zentriermembran (14) die Zentriermembran (14) aus Gummi hergestellt ist.8. Converter according to claim 2, characterized in that in the case of a cone speaker with centering membrane (14), the centering membrane (14) is made of rubber. 9. Wandler nach Anspruch 2, dadurch gekennzeichnet, daß im Falle eines Konuslautsprechers mit Zentriermembran (14) die Zentriermembran (14) aus Kunststoff hergestellt ist.9. Converter according to claim 2, characterized in that in the case of a cone speaker with centering membrane (14), the centering membrane (14) is made of plastic. 10. Wandler nach Anspruch 8 oder 9, dadurch gekennzeichnet, daß der Kunststoff oder Gummi formgeprägt ist.10. Converter according to claim 8 or 9, characterized in that the plastic or rubber is shaped.
EP79105352A 1979-01-08 1979-12-22 Dynamic transducer comprising a voice coil in an air gap filled with a magnetic fluid Ceased EP0013419A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE2900427A DE2900427B1 (en) 1979-01-08 1979-01-08 Dynamic transducer with a voice coil in an air gap filled with a magnetic fluid
DE2900427 1979-01-08

Publications (1)

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EP0013419A1 true EP0013419A1 (en) 1980-07-23

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EP79105352A Ceased EP0013419A1 (en) 1979-01-08 1979-12-22 Dynamic transducer comprising a voice coil in an air gap filled with a magnetic fluid

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US (1) US4320263A (en)
EP (1) EP0013419A1 (en)
JP (1) JPS5593399A (en)
DE (1) DE2900427B1 (en)

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GB460994A (en) * 1934-06-04 1937-02-03 Jensen Radio Mfg Company Improvements in electro-dynamic sound reproducers
US3513270A (en) * 1965-05-08 1970-05-19 Sennheiser Electronic Microphone diaphragm including spacer means between diaphragm and voice coil
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DE2900427B1 (en) * 1979-01-08 1979-08-02 Licentia Gmbh Dynamic transducer with a voice coil in an air gap filled with a magnetic fluid

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GB460994A (en) * 1934-06-04 1937-02-03 Jensen Radio Mfg Company Improvements in electro-dynamic sound reproducers
US3513270A (en) * 1965-05-08 1970-05-19 Sennheiser Electronic Microphone diaphragm including spacer means between diaphragm and voice coil
US4017694A (en) * 1976-02-18 1977-04-12 Essex Group, Inc. Method for making loudspeaker with magnetic fluid enveloping the voice coil
FR2345048A1 (en) * 1976-03-19 1977-10-14 Harwood Hugh ELECTRO-ACOUSTIC TRANSDUCER MEMBRANE
DE2716063A1 (en) * 1977-04-09 1978-10-12 Licentia Gmbh DYNAMIC CONVERTER WITH A VOICE COIL IN AN AIR GAP FILLED WITH A MAGNETIC LIQUID
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Also Published As

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US4320263A (en) 1982-03-16
JPS5593399A (en) 1980-07-15
DE2900427B1 (en) 1979-08-02

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