EP0403378B1 - Kugelmembran-Rundstrahllautsprecher mit magnetostriktivem Doppelschicht-Bändchen - Google Patents

Kugelmembran-Rundstrahllautsprecher mit magnetostriktivem Doppelschicht-Bändchen Download PDF

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Publication number
EP0403378B1
EP0403378B1 EP90401637A EP90401637A EP0403378B1 EP 0403378 B1 EP0403378 B1 EP 0403378B1 EP 90401637 A EP90401637 A EP 90401637A EP 90401637 A EP90401637 A EP 90401637A EP 0403378 B1 EP0403378 B1 EP 0403378B1
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EP
European Patent Office
Prior art keywords
strip
sphere
face
directed towards
membrane
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
EP90401637A
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English (en)
French (fr)
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EP0403378A1 (de
Inventor
Siegfried Klein
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.)
Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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Publication of EP0403378A1 publication Critical patent/EP0403378A1/de
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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
    • H04R15/00—Magnetostrictive transducers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
    • H01H2037/523—Thermally-sensitive members actuated due to deflection of bimetallic element using a corrugated bimetal

Definitions

  • the present invention relates to an omnidirectional speaker with a spherical membrane using a magnetostrictive bimetallic strip.
  • This invention is applicable to the omnidirectional broadcasting of sound waves by means of a high performance loudspeaker, with wide bandwidth, extending throughout the range of audible frequencies.
  • An omnidirectional loudspeaker is known, with a spherical membrane, having a wide bandwidth and using the phenomenon of magnetostriction.
  • This loudspeaker is described for example in European patent application No. 0 177 383, filed on August 22, 1985 in the names of the same applicants.
  • This patent application describes an omnidirectional elastic wave transducer with a large passband, and more precisely a spherical speaker using the phenomenon of magnetostriction.
  • the omnidirectional loudspeaker of spherical shape, consists of a ribbon; of a magnetostrictive material wound in a spiral, an elastic seal joining the turns of the ribbon the two ends of this ribbon are connected to means for applying to the loudspeaker thus obtained, which forms a spherical pulsating membrane, a corresponding electrical control signal sound waves to broadcast.
  • the two ends of the ribbon are located in two areas diametrically opposite of the pulsating membrane.
  • This loudspeaker also comprises means of continuous and permanent magnetic polarization, for polarizing the pulsating membrane so that the acoustic wave has an amplitude proportional to the control signal applied to the ends of the ribbon.
  • the loudspeaker described in this patent has the drawback, however, of having only a low power at low frequencies; this imperfection is mainly due to the difficulty of obtaining a large amplitude of the pulsations of the spherical membrane at low frequencies.
  • the object of the invention is to remedy this drawback and in particular to produce a loudspeaker with a spherical pulsating membrane, ensuring sufficient acoustic power in all frequencies and more particularly at low frequencies.
  • a magnetostrictive tape having at least one of its faces completely or partially covered by a thin layer of a material, such as copper, ceramic, etc..
  • This rigid thin layer gives the ribbon, as will be seen in detail below, the properties of a bimetallic strip, the deformations of which are not controlled by variations in temperature, but by the application of a current modulated electric control.
  • This current causes variations in the length of the magnetostrictive tape which, subject to the stresses of the rigid thin layer, the length of which does not vary, deforms substantially at the rate of the variations in amplitude of the modulation current.
  • FIGS. 1a and 1b will make it possible to better understand the phenomenon of magnetostrictive bimetal strip used in the loudspeaker of the invention.
  • FIG. 1a is a side view of a portion of a magnetostrictive tape M, surrounded by a coil B. In the absence of electric current in the coil B, the tape M has a length L.
  • the coil B When a current is applied to the coil B, and in the absence of a permanent continuous magnetic field, the coil induces a magnetic field in the ribbon which shrinks and then has a length L1, very little less than L.
  • Figure 1b shows laterally the magnetostrictive ribbon M, surrounded by the coil B.
  • This ribbon is here covered, on one of its faces, by a thin layer of a rigid material such as copper or ceramic for example.
  • the ribbon M and the layer R have a length L.
  • the invention uses this bimetallic strip in a spherical loudspeaker having sufficient acoustic power throughout the range of acoustic frequencies and in particular at low frequencies.
  • the invention relates to an omnidirectional loudspeaker comprising a spherical membrane, which comprises turns formed of a ribbon of a magnetostrictive material wound in a spiral according to a sphere, these turns being held by an elastic support, so that they form with said support said spherical membrane, this ribbon having two opposite faces, one of which is directed towards the inside of the sphere and the other towards the outside, and two ends situated in two diametrically opposite zones of the sphere, to be connected to an electrical control means supplying a signal corresponding to sound waves to be reproduced, and a means for continuous polarization of the membrane, characterized in that at least one of the faces of the ribbon is at least partially covered with a thin layer of rigid material.
  • the ribbon is covered by the rigid thin layer on its face directed towards the outside of the sphere.
  • the ribbon has over its entire length transverse corrugations, each corrugation having on the face of the ribbon, directed towards the inside of the sphere, a concave zone and a zone convex and, on the face of the ribbon directed towards the outside of the sphere, a concave zone and a convex zone, the rigid layer being located at least partially on the face of the ribbon directed towards the outside of the sphere, opposite the convex areas of this face.
  • the ribbon has transverse undulations over its entire length, each undulation having on the face of the ribbon directed towards the interior of the sphere, a concave zone and a convex zone and, on the face of the ribbon directed towards the outside of the sphere, a concave zone and a convex zone, the rigid layer being located partially on each face of the strip, opposite the concave zones or opposite the convex zones.
  • the means for continuous polarization of the membrane is a permanent magnet located inside said membrane.
  • the DC biasing means is a DC voltage source connected to the ends of said strip.
  • said membrane is formed of two hemispheres joined to one another.
  • FIG. 2 schematically represents a first embodiment of an omnidirectional loudspeaker, according to the invention.
  • This loudspeaker comprises a spherical membrane which comprises turns (2) of a magnetostrictive tape, wound in a spiral according to a sphere. These turns are held by an elastic support 1 which can be either a hollow sphere of an insulating and elastic material, on which the turns are glued, or a strip of an elastic material wound helically according to a sphere, this strip being located between the turns and being made integral with these.
  • the tape 2 of magnetostrictive material forms with the support 1 a spherical membrane.
  • the ribbon has two opposite faces, one of which is directed towards the inside of the sphere, and the other towards the outside of the sphere.
  • the tape 2 of magnetostrictive material comprises on at least one of its faces an at least partial coating of a thin layer of a rigid material such as copper , ceramic ... etc. It also has two ends 3, 4, located in two diametrically opposite zones of the spherical shell 1. These ends are connected to a control means 5 providing a modulation signal corresponding to sound waves to be reproduced.
  • This control means can be constituted for example, in this embodiment, by a transformer, a primary winding 6 of which receives the output signal from an amplifier.
  • the secondary winding 7 of this transformer applies this signal to the ends 3, 4, of the ribbon 2.
  • the loudspeaker also comprises a means of continuous polarization constituted here by an electric source 8 of direct voltage, one of the terminals of which is connected to the end 4 of the ribbon 2 and the other terminal of which is connected to the end 3 of this ribbon, via a choke L.
  • a decoupling capacitor 9 also appears in the figure. This capacitor is conventional in the connection of a loudspeaker to the output of an amplifier.
  • the DC voltage source induces a continuous and permanent magnetic field in the ribbon.
  • At least one of the faces of the tape 2 has a rigid thin layer completely or partially covering this face. This layer does not appear in this figure and will be described later.
  • FIG. 3 schematically represents another embodiment of the loudspeaker of FIG. 1.
  • the means for continuous polarization of the ribbon is here constituted by a permanent magnet 10 situated inside the spherical membrane.
  • This permanent magnet of cylindrical shape for example, has an axis common to the axis X of the loudspeaker.
  • the DC voltage source 8, the choke L and the decoupling capacitor 9, are not necessary and the secondary winding of the transformer 5 is directly connected to the ends of the strip 2.
  • at least l 'One of the faces of the tape 2 here also has a rigid thin layer completely or partially covering this face. This layer does not appear in this figure and will be described later.
  • FIG 4 is a schematic transverse view of an alternative embodiment of the magnetostrictive tape covered with a rigid thin layer, used in the loudspeaker of the invention.
  • the magnetostrictive tape 2 which has two opposite faces 11, 12, one (face 12) directed towards the inside I of the sphere and the other (face 11) directed towards the outside E of the sphere, is completely covered on its face 11, directed towards the outside of the sphere, by a thin layer 13 of rigid material.
  • the magnetostrictive tape can be constituted for example by a colbalt / nickel alloy, while the rigid thin layer 13 can be a layer of copper or a ceramic for example.
  • this ribbon undergoes deformations whose amplitudes are proportional to the variations in amplitude of the current. Due to the presence of the rigid layer, the ribbon undergoes deformations which are amplified in the same way as in a thermal bimetallic strip where it is temperature variations which cause such deformations. It follows that the speaker formed using such a ribbon has a very wide bandwidth in the range of audible frequencies, including for low frequencies or its power is much greater than for the speakers state of the art spherical.
  • FIG. 5 schematically represents a side view of another variant of a magnetostrictive tape used in the loudspeaker of the invention.
  • the ribbon here has undulations over its entire length transverse.
  • Each corrugation has on the face 12 of the ribbon, directed towards the interior I of the sphere, a concave zone 14A and a convex zone 14B.
  • Each corrugation also has on the face 11 of the ribbon, directed towards the outside E of the sphere, a concave zone 15A and a convex zone 15B.
  • the rigid thin layer does not extend over the whole of one of the faces of the ribbon, but it is located at least partially opposite the convex zones 15B of the face 11 of the ribbon, directed towards the outside. E of the sphere. This rigid thin layer is shown at 16 in the figure.
  • FIG. 6 schematically represents a side view of another variant of the magnetostrictive tape.
  • the magnetostrictive ribbon has transverse undulations over its entire length.
  • Each corrugation has, as in the previous embodiment, on its face 12 directed towards the interior I of the sphere, a concave zone 14A, and a convex zone 14B and on its face 11, directed towards the exterior of the sphere , a concave zone 15A and a convex zone 15B.
  • the rigid layer is here partially located opposite the zones concaves 14A and 15A on each side of the ribbon. These localized rigid thin layers are shown at 19, 20 in the figure.
  • the passage of electric current through the ribbon here causes the edges of the corrugations to spread apart.
  • FIG. 7 schematically represents a side view of another variant of a magnetostrictive tape used in the loudspeaker of the invention.
  • the rigid thin layer is here partially deposited on each of the faces of the ribbon, facing the convex zones 14B, 15B of the corrugations. These localized rigid thin layers are shown at 21, 22 in the figure.
  • the amplitude of the deformations of the ribbon in particular at low frequencies, is very large due to the bimetal effect of the structure of the ribbon described.
  • the passage of electric current through the ribbon brings the edges of the corrugations together.
  • the membrane constituted by the ribbon 2, partially covered with rigid material, and by the elastic support 1 can be formed of two hemispheres, such as represented in 23 , 24, in FIG. 1. These two hemispheres are made integral, for example by gluing the support and by welding two half-ribbons, each corresponding to one of the hemispheres.
  • the preferred embodiments of the loudspeaker which has just been described are those which use the magnetostrictive ribbon with bimetal effect, of wavy shape. It is indeed this wavy shape which provides the best acoustic performance and which ensures the simplest manufacture of the spherical loudspeaker.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
  • Diaphragms For Electromechanical Transducers (AREA)
  • Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)

Claims (7)

  1. Rundstrahllautsprecher, eine Kugelmembran enthaltend, die Windungen aufweist, gebildet aus einem Bändchen (2) aus magnetorestriktivem Material, spiralförmig einer Kugel entsprechend aufgerollt, wobei diese Windungen gehalten werden durch einen elastischen Träger (1), so daß sie mit dem genannten Träger die genannte Kugelmembran bilden, wobei dieses Bändchen zwei entgegengesetzte Seiten (11, 12) aufweist, deren eine gegen das Innere (I) der Kugel gerichtet ist und das andere gegen das Äußere (E), und zwei Enden (3, 4), in zwei diametral entgegengesetzten Zonen der Kugel befindlich, um durch eine elektrische Steuereinrichtung (5) verbunden zu werden, die ein Signal liefert, das den zu erzeugenden Schallwellen entspricht, und eine Einrichtung zur kontinuierlichen Polarisation der Membran,
    dadurch gekennzeichnet,
    daß wenigstens eine der Seiten (11) des Bändchens (2) wenigstens teilweise bedeckt ist mit einer dünnen Schicht (13) aus einem steifen Material.
  2. Lautsprecher nach Anspruch 1, dadurch gekennzeichnet, daß das Bändchen (2) auf seiner gegen das Kugeläußere (E) gekehrten Seite (11) bedeckt ist mit der dünnen Schicht (13).
  3. Lautsprecher nach Anspruch 1, dadurch gekennzeichnet, daß das Bändchen (2) auf seiner ganzen Länge Querwellen aufweist, wobei jede Welle auf der Seite (12) des Bändchens, die gegen das Kugelinnere (I) gerichtet ist, eine konkave Zone (14A) und eine konvexe Zone (14B) aufweist, und auf der Seite (11) des Bändchens, gegen das Kugeläußere (E) gerichtet, eine konkave Zone (15A) und eine konvexe Zone (15B), wobei die steife Schicht (16) wenigstens teilweise auf der Seite (11) des Bändchens lokalisiert ist, gegen das Kugeläußere gerichtet, den konvexen Zonen (15B) dieser Seite gegenüberstehend.
  4. Lautsprecher nach Anspruch 1, dadurch gekennzeichnet, daß das Bändchen (2) auf seiner ganzen Länge Querwellen aufweist, wobei jede Querwelle auf der Seite (12) des Bändchens, gegen das Kugelinnere gerichtet, eine konkave Zone (15A) und eine konvexe Zone (15B) aufweist, und auf der Seite (11) des Bändchens, gegen das Kugeläußere gerichtet, eine konkave Zone (15A) und eine konvexe Zone (15B), wobei die steife Schicht (19, 20 oder 21, 22) teilweise lokalisiert ist auf jeder Seite des Bändchens, den konkaven Zonen (14A, 15A) gegenüberstehend, oder den konvexen Zonen (14B, 15B) gegenüberstehend.
  5. Lautsprecher nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Einrichtung der kontinuierlichen Polarisation der Membran ein Permanentmagnet (10) ist, angeordnet im Innern der genannten Membran.
  6. Lautsprecher nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Einrichtung der kontinuierlichen Polarisation eine Gleichspannungsquelle (8) ist, verbunden mit den Enden des genannten Bändchens.
  7. Lautsprecher nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die genannte Membran gebildet wird aus zwei zusammengefügten Halbkugeln (23, 24).
EP90401637A 1989-06-15 1990-06-13 Kugelmembran-Rundstrahllautsprecher mit magnetostriktivem Doppelschicht-Bändchen Expired - Lifetime EP0403378B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8907960A FR2648664A1 (fr) 1989-06-15 1989-06-15 Haut-parleur omnidirectionnel a membrane spherique utilisant un ruban magnetostrictif
FR8907960 1989-06-15

Publications (2)

Publication Number Publication Date
EP0403378A1 EP0403378A1 (de) 1990-12-19
EP0403378B1 true EP0403378B1 (de) 1993-12-29

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EP90401637A Expired - Lifetime EP0403378B1 (de) 1989-06-15 1990-06-13 Kugelmembran-Rundstrahllautsprecher mit magnetostriktivem Doppelschicht-Bändchen

Country Status (5)

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US (1) US5103483A (de)
EP (1) EP0403378B1 (de)
JP (1) JPH0332200A (de)
DE (1) DE69005537T2 (de)
FR (1) FR2648664A1 (de)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5396266A (en) * 1993-06-08 1995-03-07 Technical Research Associates, Inc. Kinesthetic feedback apparatus and method
GB2376834B (en) * 1999-12-21 2003-06-25 1 Ltd Loudspeaker using an electro-active device
AUPR317901A0 (en) 2001-02-16 2001-03-15 Arnstein, Barry Electro-acoustic converter

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2761077A (en) * 1952-03-27 1956-08-28 Harris Transducer Corp Magnetostrictive ceramic transducer
DE1157266B (de) * 1961-01-11 1963-11-14 Sennheiser Electronic Magnetostriktives Wandlerelement
FR2503515B1 (fr) * 1981-04-01 1985-12-27 Klein Siegfried Haut-parleur omnidirectionnel pour les frequences aigues du spectre sonore
DE3405635A1 (de) * 1984-02-17 1985-08-22 Rainer J. 5000 Köln Haas Elektrodynamischer lautsprecher mit rundum-schallabstrahlung
US4782471A (en) * 1984-08-28 1988-11-01 Commissariat A L'energie Atomique Omnidirectional transducer of elastic waves with a wide pass band and production process
FR2619481B1 (fr) * 1987-08-14 1989-11-17 Commissariat Energie Atomique Transducteur omnidirectionnel d'ondes elastiques a large bande passante
US4843275A (en) * 1988-01-19 1989-06-27 Pennwalt Corporation Air buoyant piezoelectric polymeric film microphone
DE8803776U1 (de) * 1988-03-19 1988-05-11 Klein, Siegfried, Dr. Prof., Paris Akustoelektrischer Wandler

Also Published As

Publication number Publication date
JPH0332200A (ja) 1991-02-12
FR2648664A1 (fr) 1990-12-21
DE69005537D1 (de) 1994-02-10
EP0403378A1 (de) 1990-12-19
DE69005537T2 (de) 1994-06-23
US5103483A (en) 1992-04-07

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