EP1237394A1 - Magnetic circuit for electrodynamic loudspeaker - Google Patents

Magnetic circuit for electrodynamic loudspeaker Download PDF

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Publication number
EP1237394A1
EP1237394A1 EP02290406A EP02290406A EP1237394A1 EP 1237394 A1 EP1237394 A1 EP 1237394A1 EP 02290406 A EP02290406 A EP 02290406A EP 02290406 A EP02290406 A EP 02290406A EP 1237394 A1 EP1237394 A1 EP 1237394A1
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EP
European Patent Office
Prior art keywords
magnet
core
magnetic circuit
cylinder head
coil
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EP02290406A
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German (de)
French (fr)
Inventor
Philippe Lesage
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PHL AUDIO
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PHL AUDIO
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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

Definitions

  • the present invention relates to magnetic circuits for loudspeakers electrodynamics, as well as such speakers having these magnetic circuits.
  • the so-called "central magnet” is particularly advantageous with regard to the magnetic energy to be supplied by the magnet - which may be only 1.6 greater to that desired in the air gap to move the coil axially mobile-- and very low magnetic leaks.
  • This last property therefore makes it possible to use the loudspeaker provided with a magnetic circuit central magnet near equipment sensitive to magnetic fields, such as video monitors, calculators, on-board instruments planes, etc ...
  • the circuits magnetic with central magnet can be, with equal power, of smaller dimensions than, for example, magnetic circuits with annular magnet, especially since said magnet, if it is made of a very energetic material, such as that containing rare earths, can itself be small.
  • a very energetic material such as that containing rare earths
  • the diameter of said magnet is equal to that of the core, so the travel height for the coil can be determined by the sum of the heights of the core and the central magnet. This results in a limitation of the surface of the magnet and therefore the high performance of these known magnetic circuits. In indeed, if one wishes to increase the energy of the magnet, the only possibility is to increase its thickness, which leads to jointly increase its internal reluctance, and therefore limiting the performance of the magnetic circuit.
  • the object of the present invention is to remedy these drawbacks by improving magnetic circuits with central magnets to increase them further performance by reducing the internal reluctance.
  • the diameter of the magnet can be chosen to achieve superior performance at the same air gap to those of the prior art. Because, to make a magnetic circuit more efficient, it is preferable to increase the surface of the magnet by increasing its diameter rather than increasing its thickness, the reluctance of a disc-shaped magnet being proportional to its height and inversely proportional to its surface.
  • the structure according to the present invention leads to an increase in the core and cylinder head height, and possibly an increase diameter of the latter.
  • the loudspeaker comprising the magnetic circuit according to the present invention is of high power, which requires a core cooling ventilation, or is of the coaxial type requiring a central duct
  • said magnetic circuit is provided with a axial passage through said flat bottom of the cylinder head, said magnet and said core.
  • FIGS. 2, 3 and 4 similar to elements in FIG. 1 have the same reference than these, but assigned a specific index.
  • Figure 1 illustrates, in schematic axial section, a magnetic circuit known, of the central magnet type, intended for an electrodynamic loudspeaker.
  • Figures 2, 3 and 4 illustrate, in schematic axial sections, three embodiments of the magnetic circuit according to this invention.
  • the magnetic circuits of Figures 1 to 4 have identical air gaps, as well as travel heights also identical.
  • the winding 11B is structurally bonded to the support 11A and the assembly 11A-11B is arranged coaxially with the axis of revolution R-R.
  • the winding 11B is arranged in the air gap 10 and the coil 11 can move parallel and coaxially to said axis of revolution R-R, as schematically illustrated by the double arrow 12.
  • the coil 11 is, in known manner and not shown, secured to the speaker diaphragm (not shown) and its suspensions that are the spider and the peripheral edge of the cone (also not shown) and which allow said coil only axial movements by prohibiting any lateral movement that could cause friction of the winding 11B against the edge of the opening 7.
  • the axial position of the coil 11 is such that the plane median 13 of air gap 10 (orthogonal to axis R-R) passes through the middle of the winding 11B, as shown in FIG. 1.
  • the 11B winding is subjected to the magnetic field prevailing in the air gap 10, so that, when it is traversed by a modulation current, the coil 11 moves along the axis of revolution R-R.
  • the magnet 8 has a diameter identical to that of the core 9, so that the cylindrical walls of said magnet and of said core are in extension of one another.
  • the edge 11S thereof, disposed on the side of the bottom 3 is located opposite said bottom 3 and is spaced therefrom by a distance d , representing the height available for moving the coil inside the cylinder head 2.
  • this distance d is determined to be greater than the maximum stroke that the coil 11 can make, inside the cylinder head 2, towards the bottom 3.
  • the distance D separating the bottom 3 from the external face 6E of the annular rim 6 is representative of the distance d , significant of the height available.
  • FIG. 2 there is shown a first embodiment 1.1 of the magnetic circuit for electrodynamic loudspeaker conforming to the present invention.
  • the coil 11 For simplification purposes, the coil 11.
  • the diameter of the magnet 8.1 is larger than that of the core 9.1 and forms a peripheral projection 14, annular and radial, of radial amplitude s , relative to said core 9.1.
  • the radial amplitude s of the projection 14 is, in the example shown in FIG. 2, of the order of the thickness e of the magnet 8.1. More generally, this radial amplitude s could be at most equal to three times the thickness e .
  • the core 9.2 of the magnetic circuit 1.2 differs from the core 9.1 of the magnetic circuit 1.1 in that it comprises, on the side of said magnet 8.2, a protruding heel 15 in the form of a disc, the diameter of which is greater than that of the rest of the 9.2 kernel, but smaller than that of the 8.2 magnet, this the latter also forming the peripheral projection 14, annular and radial, relative to the periphery of the heel 15.
  • the magnetic circuit 1.3 of FIG. 4 comprises a yoke 2.3, an 8.3 magnet and a 9.3 core similar to the corresponding elements 2.2, 8.2 and 9.2 of the magnetic circuit 1.2.
  • the magnets 8.1, 8.2 and 8.3 are made of ternary alloy sintered neodymium-iron-boron.

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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)

Abstract

The electrodynamic loudspeaker magnetic circuit (1.1) has a basin shaped body (2.1) and a cylindrical center section (9.1). There is a magnetic section (14) with a diameter (8.1) larger than the cylindrical center section. The effect of having the magnetic overlap sections is to limit the movement of the cylindrical center section.

Description

La présente invention concerne les circuits magnétiques pour haut-parleurs électrodynamiques, ainsi que de tels haut-parleurs comportant ces circuits magnétiques.The present invention relates to magnetic circuits for loudspeakers electrodynamics, as well as such speakers having these magnetic circuits.

On connaít de nombreuses structures de circuit magnétique pour haut-parleur électromagnétique. Parmi ces structures connues, celle dite "à aimant central" est particulièrement avantageuse en ce qui concerne l'énergie magnétique à fournir par l'aimant --qui peut n'être que 1,6 supérieure à celle désirée dans l'entrefer pour déplacer axialement la bobine mobile-- et les très faibles fuites magnétiques. Cette dernière propriété permet donc d'utiliser le haut-parleur pourvu d'un circuit magnétique à aimant central à proximité d'équipements sensibles aux champs magnétiques, comme les moniteurs vidéo, les calculateurs, les instruments à bord des avions, etc ...We know many magnetic circuit structures for electromagnetic speaker. Among these known structures, the so-called "central magnet" is particularly advantageous with regard to the magnetic energy to be supplied by the magnet - which may be only 1.6 greater to that desired in the air gap to move the coil axially mobile-- and very low magnetic leaks. This last property therefore makes it possible to use the loudspeaker provided with a magnetic circuit central magnet near equipment sensitive to magnetic fields, such as video monitors, calculators, on-board instruments planes, etc ...

Du fait de leurs performances énergétiques remarquables, les circuits magnétiques à aimant central peuvent être, à puissance égale, de plus petites dimensions que, par exemple, les circuits magnétiques à aimant annulaire, et ceci d'autant plus que ledit aimant, s'il est réalisé en une matière très énergétique, telle que celle contenant des terres rares, peut lui-même être de petites dimensions. A titre d'exemple de tels aimants très énergétiques, on peut citer ceux en alliage ternaire fritté de néodyme-fer-bore.Due to their remarkable energy performance, the circuits magnetic with central magnet can be, with equal power, of smaller dimensions than, for example, magnetic circuits with annular magnet, especially since said magnet, if it is made of a very energetic material, such as that containing rare earths, can itself be small. As an example of such very energetic magnets, we can mention those made of sintered ternary alloy of neodymium-iron-boron.

On rappellera qu'un circuit magnétique moderne du type à "aimant central" pour haut-parleur électrodynamique présente une forme de révolution autour d'un axe de symétrie et comporte :

  • une culasse en forme de cuvette à fond plat, dont le bord, opposé audit fond, est pourvu d'un rebord annulaire périphérique faisant saillie vers ledit axe par rapport à la paroi latérale de ladite cuvette et délimitant une ouverture circulaire en retrait par rapport à ladite paroi latérale ;
  • un aimant en forme de disque, disposé centralement à l'intérieur de ladite culasse et porté par ledit fond plat de celle-ci ; et
  • un noyau cylindrique, disposé centralement à l'intérieur de ladite culasse et porté par ledit aimant, la partie dudit noyau opposée audit aimant se trouvant en regard de ladite ouverture circulaire de la culasse et déterminant avec celle-ci un entrefer annulaire, dans lequel ladite bobine mobile est disposée coaxialement à l'axe dudit circuit magnétique en pouvant se déplacer parallèlement et coaxialement audit axe, la hauteur de débattement disponible pour la bobine à l'intérieur de ladite culasse étant supérieure à la course maximale que ladite bobine peut effectuer, à l'intérieur de ladite culasse, en direction du fond de celle-ci.
It will be recalled that a modern magnetic circuit of the "central magnet" type for electrodynamic loudspeaker has a shape of revolution around an axis of symmetry and comprises:
  • a bowl-shaped cylinder head with a flat bottom, the edge of which, opposite said bottom, is provided with a peripheral annular rim projecting towards said axis relative to the side wall of said bowl and delimiting a circular opening recessed with respect to said side wall;
  • a disc-shaped magnet, centrally disposed inside said cylinder head and carried by said flat bottom thereof; and
  • a cylindrical core, disposed centrally inside said cylinder head and carried by said magnet, the part of said core opposite said magnet lying opposite said circular opening of the cylinder head and determining therewith an annular air gap, in which said movable coil is arranged coaxially to the axis of said magnetic circuit, being able to move parallel and coaxially to said axis, the clearance available for the coil inside said cylinder head being greater than the maximum stroke that said coil can perform, at the interior of said cylinder head, towards the bottom thereof.

Dans les circuits magnétiques connus de ce type, le diamètre dudit aimant est égal à celui du noyau, de sorte que la hauteur de débattement pour la bobine peut être déterminée par la somme des hauteurs du noyau et de l'aimant central. Il en résulte une limitation de la surface de l'aimant et donc des performances élevées de ces circuits magnétiques connus. En effet, si l'on désire augmenter l'énergie de l'aimant, la seule possibilité est d'augmenter son épaisseur, ce qui conduit à augmenter conjointement sa réluctance interne, et donc à limiter la performance du circuit magnétique.In known magnetic circuits of this type, the diameter of said magnet is equal to that of the core, so the travel height for the coil can be determined by the sum of the heights of the core and the central magnet. This results in a limitation of the surface of the magnet and therefore the high performance of these known magnetic circuits. In indeed, if one wishes to increase the energy of the magnet, the only possibility is to increase its thickness, which leads to jointly increase its internal reluctance, and therefore limiting the performance of the magnetic circuit.

La présente invention a pour objet de remédier à ces inconvénients en perfectionnant les circuits magnétiques à aimant central pour en augmenter encore les performances en en réduisant la réluctance interne.The object of the present invention is to remedy these drawbacks by improving magnetic circuits with central magnets to increase them further performance by reducing the internal reluctance.

A cette fin, selon l'invention, le circuit magnétique à aimant central pour haut-parleur électrodynamique présentant la structure rappelée ci-dessus, est remarquable en ce que :

  • le diamètre dudit aimant est plus grand que celui dudit noyau, de sorte que ledit aimant présente une saillie périphérique, annulaire et radiale, par rapport audit noyau ; et
  • la hauteur de débattement de la bobine est limitée, du côté dudit aimant, par ladite saillie périphérique, de sorte que cette hauteur de débattement est déterminée uniquement par ledit noyau.
To this end, according to the invention, the magnetic circuit with central magnet for electrodynamic loudspeaker having the structure recalled above, is remarkable in that:
  • the diameter of said magnet is larger than that of said core, so that said magnet has a peripheral annular and radial projection relative to said core; and
  • the travel height of the coil is limited, on the side of said magnet, by said peripheral projection, so that this travel height is determined solely by said core.

Ainsi, grâce à la présente invention, le diamètre de l'aimant peut être choisi pour atteindre, à entrefer identique, des performances supérieures à celles de l'art antérieur. Car, pour rendre un circuit magnétique plus performant, il est préférable d'augmenter la surface de l'aimant en augmentant son diamètre plutôt que d'augmenter son épaisseur, la réluctance d'un aimant en forme de disque étant proportionnelle à sa hauteur et inversement proportionnelle à sa surface.Thus, thanks to the present invention, the diameter of the magnet can be chosen to achieve superior performance at the same air gap to those of the prior art. Because, to make a magnetic circuit more efficient, it is preferable to increase the surface of the magnet by increasing its diameter rather than increasing its thickness, the reluctance of a disc-shaped magnet being proportional to its height and inversely proportional to its surface.

Bien entendu, à débattement égal pour la bobine mobile, la structure conforme à la présente invention entraíne une augmentation de la hauteur du noyau et de la culasse, ainsi qu'éventuellement une augmentation de diamètre de celle-ci. Cependant, ces augmentations de dimensions --de faibles amplitudes-- permettent au circuit magnétique de l'invention de dépasser notablement les performances déjà élevées des circuits magnétiques connus, rappelées ci-dessus.Of course, at equal clearance for the voice coil, the structure according to the present invention leads to an increase in the core and cylinder head height, and possibly an increase diameter of the latter. However, these dimensional increases - low amplitudes - allow the magnetic circuit of the invention significantly exceed the already high performance of magnetic circuits known, recalled above.

L'expérience et le calcul ont montré qu'une importante augmentation des performances pouvait déjà être obtenue lorsque la saillie radiale périphérique de l'aimant par rapport au noyau était au plus égale à trois fois l'épaisseur dudit aimant, par exemple de l'ordre de une ou deux fois cette épaisseur.Experience and calculation have shown that a significant increase performance could already be obtained when the radial projection magnet device relative to the core was at most three times the thickness of said magnet, for example of the order of once or twice this thickness.

Pour abaisser encore la réluctance interne dudit aimant, et donc augmenter les performances du circuit magnétique, ce dernier peut, de plus, être tel que :

  • ledit noyau comporte, au contact dudit aimant, un talon saillant en forme de disque, dont le diamètre est plus grand que celui du reste dudit noyau mais plus petit que celui dudit aimant ; et
  • la hauteur de débattement pour la bobine est limitée, du côté dudit aimant, par ledit talon saillant.
To further lower the internal reluctance of said magnet, and therefore increase the performance of the magnetic circuit, the latter can, moreover, be such that:
  • said core comprises, in contact with said magnet, a protruding heel in the form of a disc, the diameter of which is greater than that of the rest of said core but smaller than that of said magnet; and
  • the clearance height for the coil is limited, on the side of said magnet, by said projecting heel.

Là encore, les augmentations de performances qui résultent d'une telle structure justifient très amplement les augmentations de dimensions inhérentes.Again, the performance increases that result from such structure amply justify the increases in size inherent.

Dans le cas où le haut-parleur comportant le circuit magnétique conforme à la présente invention est de forte puissance, ce qui nécessite une ventilation de refroidissement du noyau, ou bien est du type coaxial nécessitant un conduit central, ledit circuit magnétique est pourvu d'un passage axial traversant ledit fond plat de la culasse, ledit aimant et ledit noyau.In the case where the loudspeaker comprising the magnetic circuit according to the present invention is of high power, which requires a core cooling ventilation, or is of the coaxial type requiring a central duct, said magnetic circuit is provided with a axial passage through said flat bottom of the cylinder head, said magnet and said core.

On remarquera qu'un tel passage axial est possible, grâce à l'invention, du fait que la section de l'aimant peut être choisie suffisamment grande, grâce à la saillie périphérique dudit aimant, pour compenser la perte de matière magnétique entraínée par ledit passage.It will be noted that such an axial passage is possible, thanks to the invention, that the magnet section can be chosen sufficiently large, thanks to the peripheral projection of said magnet, to compensate for the loss of magnetic material caused by said passage.

Les figures du dessin annexé feront bien comprendre comment l'invention peut être réalisée. Sur ces figures, les éléments des figures 2, 3 et 4 semblables à des éléments de la figure 1 portent la même référence que ces derniers, mais affectée d'un indice spécifique.The figures in the accompanying drawing will make it clear how the invention can be realized. In these figures, the elements of FIGS. 2, 3 and 4 similar to elements in FIG. 1 have the same reference than these, but assigned a specific index.

La figure 1 illustre, en coupe axiale schématique, un circuit magnétique connu, du type à aimant central, destiné à un haut-parleur électrodynamique.Figure 1 illustrates, in schematic axial section, a magnetic circuit known, of the central magnet type, intended for an electrodynamic loudspeaker.

Les figures 2, 3 et 4 illustrent, en coupes axiales schématiques, trois modes de réalisation du circuit magnétique conforme à la présente invention.Figures 2, 3 and 4 illustrate, in schematic axial sections, three embodiments of the magnetic circuit according to this invention.

A des fins de comparaison, les circuits magnétiques des figures 1 à 4 présentent des entrefers identiques, ainsi que des hauteurs de débattement de bobine également identiques.For comparison purposes, the magnetic circuits of Figures 1 to 4 have identical air gaps, as well as travel heights also identical.

Le circuit magnétique 1 pour haut-parleur électrodynamique, de type connu et représenté sur la figure 1, présente une forme de révolution autour d'un axe R-R. Le circuit magnétique 1 comporte :

  • une culasse 2 en forme de cuvette de révolution autour de l'axe R-R, par exemple réalisée en acier doux, comprenant un fond plat 3 et une paroi latérale cylindrique 4. Du côté opposé au fond 3, le bord 5 de la paroi 4 est pourvu d'un rebord annulaire 6 périphérique faisant saillie, en direction dudit axe de révolution R-R, par rapport à la paroi latérale 4. Le rebord annulaire 6 délimite une ouverture circulaire 7, centrée sur l'axe de révolution R-R et en retrait par rapport à la paroi latérale 4 ;
  • un aimant 8 en forme de disque, disposé à l'intérieur de la culasse 2, coaxialement à l'axe de révolution R-R et porté par le fond plat 3 de la culasse 2. L'aimant 8 est par exemple constitué d'un alliage ternaire fritté de néodyme-fer-bore ; et
  • un noyau cylindrique 9, par exemple réalisé en acier doux, disposé à l'intérieur de la culasse 2, coaxialement à l'axe de révolution R-R, et porté par ledit aimant 8. La partie 9A du noyau 9, opposée à l'aimant 8, se trouve en regard de l'ouverture circulaire 7 de la culasse 2 et détermine avec elle un entrefer annulaire 10.
The magnetic circuit 1 for electrodynamic loudspeaker, of known type and shown in Figure 1, has a shape of revolution around an axis RR. The magnetic circuit 1 includes:
  • a cylinder head 2 in the form of a bowl of revolution around the axis RR, for example made of mild steel, comprising a flat bottom 3 and a cylindrical side wall 4. On the side opposite the bottom 3, the edge 5 of the wall 4 is provided with a peripheral annular rim 6 projecting in the direction of said axis of revolution RR, with respect to the side wall 4. The annular rim 6 delimits a circular opening 7, centered on the axis of revolution RR and recessed with respect to to the side wall 4;
  • a magnet 8 in the form of a disc, placed inside the cylinder head 2, coaxial with the axis of revolution RR and carried by the flat bottom 3 of the cylinder head 2. The magnet 8 is for example made of an alloy sintered ternary of neodymium-iron-boron; and
  • a cylindrical core 9, for example made of mild steel, disposed inside the cylinder head 2, coaxial with the axis of revolution RR, and carried by said magnet 8. The part 9A of the core 9, opposite the magnet 8, is located opposite the circular opening 7 of the cylinder head 2 and determines with it an annular air gap 10.

Par ailleurs, de façon connue, le haut-parleur électrodynamique comportant le circuit magnétique 1 comprend une bobine mobile 11, constituée d'un support cylindrique 11A, entourant le noyau 9 et réalisé en une matière rigide, électriquement non-conductrice et résistant à la chaleur, et d'un bobinage hélicoïdal 11B, porté par la paroi cylindrique dudit support 11A. Le bobinage 11B est collé structurellement sur le support 11A et l'ensemble 11A-11B est disposé coaxialement à l'axe de révolution R-R. Furthermore, in known manner, the electrodynamic loudspeaker comprising the magnetic circuit 1 comprises a moving coil 11, consisting a cylindrical support 11A, surrounding the core 9 and produced in a rigid, electrically non-conductive and heat-resistant material, and a helical winding 11B, carried by the cylindrical wall of said support 11A. The winding 11B is structurally bonded to the support 11A and the assembly 11A-11B is arranged coaxially with the axis of revolution R-R.

Le bobinage 11B est disposé dans l'entrefer 10 et la bobine 11 peut se déplacer parallèlement et coaxialement audit axe de révolution R-R, comme cela est illustré schématiquement par la double flèche 12.The winding 11B is arranged in the air gap 10 and the coil 11 can move parallel and coaxially to said axis of revolution R-R, as schematically illustrated by the double arrow 12.

La bobine 11 est, de façon connue et non représentée, solidaire de la membrane du haut-parleur (non représentée) et de ses suspensions que sont le spider et le bord périphérique du cône (également non représentés) et qui ne permettent à ladite bobine que des mouvements axiaux en interdisant tout déplacement latéral qui risquerait d'entraíner le frottement du bobinage 11B contre le bord de l'ouverture 7.The coil 11 is, in known manner and not shown, secured to the speaker diaphragm (not shown) and its suspensions that are the spider and the peripheral edge of the cone (also not shown) and which allow said coil only axial movements by prohibiting any lateral movement that could cause friction of the winding 11B against the edge of the opening 7.

Au repos, la position axiale de la bobine 11 est telle que le plan médian 13 de l'entrefer 10 (orthogonal à l'axe R-R) passe par le milieu du bobinage 11B, comme cela est représenté sur la figure 1. Bien entendu, le bobinage 11B est soumis au champ magnétique régnant dans l'entrefer 10, de sorte que, lorsqu'il est parcouru par un courant de modulation, la bobine 11 se déplace le long de l'axe de révolution R-R.At rest, the axial position of the coil 11 is such that the plane median 13 of air gap 10 (orthogonal to axis R-R) passes through the middle of the winding 11B, as shown in FIG. 1. Of course, the 11B winding is subjected to the magnetic field prevailing in the air gap 10, so that, when it is traversed by a modulation current, the coil 11 moves along the axis of revolution R-R.

Dans le circuit magnétique 1, connu et représenté sur la figure 1, l'aimant 8 présente un diamètre identique à celui du noyau 9, de sorte que les parois cylindriques dudit aimant et dudit noyau sont en prolongement l'une de l'autre. Par suite, dans la position de repos de la bobine 11, le bord 11S de celle-ci, disposé du côté du fond 3, se trouve en regard dudit fond 3 et est écarté de celui-ci d'une distance d, représentant la hauteur disponible pour le déplacement de la bobine à l'intérieur de la culasse 2. Bien entendu, afin d'éviter que la bobine 11 vienne heurter le fond 3 en risquant d'être détruite, cette distance d est déterminée pour être supérieure à la course maximale que la bobine 11 peut effectuer, à l'intérieur de la culasse 2, en direction du fond 3.In the magnetic circuit 1, known and represented in FIG. 1, the magnet 8 has a diameter identical to that of the core 9, so that the cylindrical walls of said magnet and of said core are in extension of one another. As a result, in the rest position of the coil 11, the edge 11S thereof, disposed on the side of the bottom 3, is located opposite said bottom 3 and is spaced therefrom by a distance d , representing the height available for moving the coil inside the cylinder head 2. Of course, in order to prevent the coil 11 from striking the bottom 3, risking being destroyed, this distance d is determined to be greater than the maximum stroke that the coil 11 can make, inside the cylinder head 2, towards the bottom 3.

On remarquera que, pour une bobine 11 déterminée, la distance D séparant le fond 3 de la face externe 6E du rebord annulaire 6 est représentative de la distance d, significative de la hauteur disponible. It will be noted that, for a determined coil 11, the distance D separating the bottom 3 from the external face 6E of the annular rim 6 is representative of the distance d , significant of the height available.

Sur la figure 2, on a représenté un premier mode de réalisation 1.1 du circuit magnétique pour haut-parleur électrodynamique conforme à la présente invention. A des fins de simplification, on n'a pas représenté la bobine 11. Par ailleurs, chaque élément de la figure 2, qui correspond à un élément 2 à 10 de la figure 1, porte le même chiffre de référence, affecté de l'indice 1.In Figure 2, there is shown a first embodiment 1.1 of the magnetic circuit for electrodynamic loudspeaker conforming to the present invention. For simplification purposes, the coil 11. Furthermore, each element of FIG. 2, which corresponds to a element 2 to 10 of figure 1, has the same reference number, assigned of index 1.

Dans le circuit magnétique 1.1, le diamètre de l'aimant 8.1 est plus grand que celui du noyau 9.1 et forme une saillie périphérique 14, annulaire et radiale d'amplitude radiale s, par rapport audit noyau 9.1. L'amplitude radiale s de la saillie 14 est, dans l'exemple représenté sur la figure 2, de l'ordre de l'épaisseur e de l'aimant 8.1. De façon plus générale, cette amplitude radiale s pourrait être au plus égale à trois fois l'épaisseur e.In the magnetic circuit 1.1, the diameter of the magnet 8.1 is larger than that of the core 9.1 and forms a peripheral projection 14, annular and radial, of radial amplitude s , relative to said core 9.1. The radial amplitude s of the projection 14 is, in the example shown in FIG. 2, of the order of the thickness e of the magnet 8.1. More generally, this radial amplitude s could be at most equal to three times the thickness e .

On voit que, dans le circuit magnétique 1.1, la hauteur de débattement D pour la bobine est limitée, du côté de l'aimant 8.1, par la saillie périphérique 14. La bobine 11 ne se déplace donc qu'en regard du noyau 9.1.We see that, in the magnetic circuit 1.1, the clearance height D for the coil is limited, on the side of magnet 8.1, by the projection peripheral 14. The coil 11 therefore only moves opposite the core 9.1.

Dans la variante de réalisation 1.2 du circuit magnétique selon la présente invention, illustrée schématiquement sur la figure 3, on retrouve une culasse 2.2 et un aimant 8.2, respectivement semblables ou identiques à la culasse 2.1 et à l'aimant 8.1 de la figure 2.In the alternative embodiment 1.2 of the magnetic circuit according to the present invention, illustrated schematically in Figure 3, we find a cylinder head 2.2 and a magnet 8.2, respectively similar or identical to the cylinder head 2.1 and to the magnet 8.1 of FIG. 2.

Le noyau 9.2 du circuit magnétique 1.2 diffère du noyau 9.1 du circuit magnétique 1.1 en ce qu'il comporte, du côté dudit aimant 8.2, un talon saillant 15 en forme de disque, dont le diamètre est plus grand que celui du reste du noyau 9.2, mais plus petit que celui de l'aimant 8.2, ce dernier formant également la saillie périphérique 14, annulaire et radiale, par rapport à la périphérie du talon 15. The core 9.2 of the magnetic circuit 1.2 differs from the core 9.1 of the magnetic circuit 1.1 in that it comprises, on the side of said magnet 8.2, a protruding heel 15 in the form of a disc, the diameter of which is greater than that of the rest of the 9.2 kernel, but smaller than that of the 8.2 magnet, this the latter also forming the peripheral projection 14, annular and radial, relative to the periphery of the heel 15.

Le circuit magnétique 1.3 de la figure 4 comporte une culasse 2.3, un aimant 8.3 et un noyau 9.3 semblables aux éléments correspondants 2.2, 8.2 et 9.2 du circuit magnétique 1.2.The magnetic circuit 1.3 of FIG. 4 comprises a yoke 2.3, an 8.3 magnet and a 9.3 core similar to the corresponding elements 2.2, 8.2 and 9.2 of the magnetic circuit 1.2.

La seule différence réside en ce que, autour de l'axe R3-R3, il est prévu un passage 16 traversant axialement ledit circuit magnétique 1.3 et constitué d'une suite de trous 17, 18 et 19, respectivement pratiqués dans le fond plat 3.3, l'aimant 8.3 et le noyau 9.3.The only difference is that, around the R3-R3 axis, it is provided a passage 16 axially passing through said magnetic circuit 1.3 and consisting of a series of holes 17, 18 and 19, respectively made in the flat bottom 3.3, the magnet 8.3 and the core 9.3.

De préférence, les aimants 8.1, 8.2 et 8.3 sont en alliage ternaire fritté de néodyme-fer-bore.Preferably, the magnets 8.1, 8.2 and 8.3 are made of ternary alloy sintered neodymium-iron-boron.

De la description qui précède, on comprendra aisément que, grâce à la présente invention, on obtient des circuits magnétiques particulièrement performants, même pour des petits diamètres de noyau 9.1, 9.2 et 9.3. Ainsi, les haut-parleurs électrodynamiques incorporant ces circuits magnétiques peuvent eux-mêmes présenter des performances élevées.From the foregoing description, it will be readily understood that, thanks to the present invention, particularly magnetic circuits are obtained efficient, even for small core diameters 9.1, 9.2 and 9.3. Thus, the electrodynamic loudspeakers incorporating these circuits Magnetics can themselves exhibit high performance.

Claims (7)

Circuit magnétique (1.1, 1.2, 1.3) pour haut-parleur électrodynamique à bobine mobile, ledit circuit magnétique présentant une forme de révolution autour d'un axe de symétrie (R1-R1 ; R2-R2 ; R3-R3) et comportant : une culasse (2.1 ; 2.2 ; 2.3) en forme de cuvette à fond plat, dont le bord, opposé audit fond, est pourvu d'un rebord annulaire périphérique (6.1 ; 6.2 ; 6.3) faisant saillie vers ledit axe par rapport à la paroi latérale de ladite cuvette et délimitant une ouverture circulaire (7.1 ; 7.2 ; 7.3) en retrait par rapport à ladite paroi latérale ; un aimant (8.1 ; 8.2 ; 8.3) en forme de disque, disposé centralement à l'intérieur de ladite culasse et porté par ledit fond plat (3.1 ; 3.2 ; 3.3) de celle-ci ; et un noyau cylindrique (9.1 ; 9.2 ; 9.3), disposé centralement à l'intérieur de ladite culasse et porté par ledit aimant, la partie dudit noyau opposée audit aimant se trouvant en regard de ladite ouverture circulaire de la culasse et déterminant avec celle-ci un entrefer annulaire (10.1 ; 10.2 ; 10.3), dans lequel ladite bobine mobile est disposée coaxialement à l'axe dudit circuit magnétique en pouvant se déplacer parallèlement et coaxialement audit axe, la hauteur de débattement disponible (D) pour la bobine à l'intérieur de ladite culasse étant supérieure à la course maximale que ladite bobine peut effectuer, à l'intérieur de ladite culasse, en direction du fond de celle-ci, caractérisé en ce que : le diamètre dudit aimant (8.1 ; 8.2 ; 8.3) est plus grand que celui dudit noyau (9.1 ; 9.2 ; 9.3), de sorte que ledit aimant présente une saillie périphérique (14), annulaire et radiale par rapport audit noyau ; et la hauteur de débattement pour la bobine est limitée, du côté dudit aimant, par ladite saillie périphérique, de sorte que cette hauteur de débattement est déterminée uniquement par ledit noyau. Magnetic circuit (1.1, 1.2, 1.3) for an electrodynamic loudspeaker with a moving coil, said magnetic circuit having a shape of revolution around an axis of symmetry (R1-R1; R2-R2; R3-R3) and comprising: a cylinder head (2.1; 2.2; 2.3) in the form of a flat-bottomed bowl, the edge of which, opposite said bottom, is provided with a peripheral annular rim (6.1; 6.2; 6.3) projecting towards said axis relative to the wall lateral of said bowl and delimiting a circular opening (7.1; 7.2; 7.3) set back relative to said lateral wall; a magnet (8.1; 8.2; 8.3) in the form of a disc, disposed centrally inside said cylinder head and carried by said flat bottom (3.1; 3.2; 3.3) thereof; and a cylindrical core (9.1; 9.2; 9.3), disposed centrally inside said cylinder head and carried by said magnet, the part of said core opposite said magnet facing said circular opening of the cylinder head and determining therewith an annular air gap (10.1; 10.2; 10.3), in which said voice coil is arranged coaxially to the axis of said magnetic circuit, being able to move parallel and coaxially to said axis, the available clearance height (D) for the coil at inside of said cylinder head being greater than the maximum stroke that said coil can perform, inside said cylinder head, in the direction of the bottom thereof, characterized in that : the diameter of said magnet (8.1; 8.2; 8.3) is larger than that of said core (9.1; 9.2; 9.3), so that said magnet has a peripheral projection (14), annular and radial relative to said core; and the clearance height for the coil is limited, on the side of said magnet, by said peripheral projection, so that this clearance height is determined solely by said core. Circuit magnétique selon la revendication 1,
caractérisé en ce que la saillie radiale périphérique (14) de l'aimant par rapport au noyau est au plus égale à trois fois l'épaisseur (e) dudit aimant.Magnetic circuit according to claim 1,
characterized in that the peripheral radial projection (14) of the magnet relative to the core is at most equal to three times the thickness (e) of said magnet. Circuit magnétique selon la revendication 2,
caractérisé en ce que la saillie radiale périphérique (14) de l'aimant par rapport au noyau est de l'ordre de l'épaisseur dudit aimant.Magnetic circuit according to claim 2,
characterized in that the peripheral radial projection (14) of the magnet relative to the core is of the order of the thickness of said magnet. Circuit magnétique selon l'une des revendications 1 à 3,
caractérisé en ce que : ledit noyau comporte, au contact dudit aimant, un talon saillant (15) en forme de disque, dont le diamètre est plus grand que celui du reste dudit noyau (9.2 ; 9.3) mais plus petit que celui dudit aimant (8.2 ; 8.3) ; et la hauteur de débattement pour la bobine est limitée, du côté dudit aimant, par ledit talon saillant (15). Magnetic circuit according to one of claims 1 to 3,
characterized in that : said core comprises, in contact with said magnet, a projecting heel (15) in the form of a disc, the diameter of which is larger than that of the rest of said core (9.2; 9.3) but smaller than that of said magnet (8.2; 8.3); and the clearance height for the coil is limited, on the side of said magnet, by said projecting heel (15). Circuit magnétique selon l'une des revendications 1 à 4,
caractérisé en ce qu'il comporte un passage axial (16) traversant le fond plat (3.3) de ladite culasse (2.3), ledit aimant (8.3) et ledit noyau (9.3).Magnetic circuit according to one of Claims 1 to 4,
characterized in that it comprises an axial passage (16) passing through the flat bottom (3.3) of said cylinder head (2.3), said magnet (8.3) and said core (9.3). Circuit magnétique selon l'une des revendications 1 à 5,
caractérisé en ce que ledit aimant (8.1 ; 8.2 ; 8.3) est en alliage ternaire fritté de néodyme-fer-bore.Magnetic circuit according to one of claims 1 to 5,
characterized in that said magnet (8.1; 8.2; 8.3) is made of sintered ternary alloy of neodymium-iron-boron. Haut-parleur électrodynamique,
caractérisé en ce qu'il comporte un circuit magnétique (1.1 ; 1.2 ; 1.3) tel que spécifié sous l'une des revendications 1 à 6.Electrodynamic speaker,
characterized in that it comprises a magnetic circuit (1.1; 1.2; 1.3) as specified under one of claims 1 to 6.
EP02290406A 2001-03-01 2002-02-20 Magnetic circuit for electrodynamic loudspeaker Withdrawn EP1237394A1 (en)

Applications Claiming Priority (2)

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FR0102807 2001-03-01
FR0102807A FR2821710B1 (en) 2001-03-01 2001-03-01 MAGNETIC CIRCUIT FOR ELECTRODYNAMIC SPEAKER

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DE102009038593A1 (en) * 2009-08-26 2011-03-03 Beyerdynamic Gmbh & Co. Kg Transducer magnet system

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JPH04259198A (en) * 1991-02-13 1992-09-14 Sony Corp Speaker unit
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