• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The invention relates to a magnet system (100) for an electromechanical transducer; wherein said magnet system comprises a first set (2) of magnets and a second set (4) of magnets; wherein said first set (2) of magnets comprises a first, inner annular magnet (6) and a first outer, annular magnet (8); wherein said second set (4) of magnets comprises a second, inner 5 annular magnet (10) and a second, outer annular magnet (12); wherein said first, inner annular magnet (6) is arranged in the interior of said first outer annular magnet (8); wherein said second inner annular magnet (10) is arranged in the interior of said second outer annular magnet (12); wherein the magnetic polarity in respect of said first, inner annular magnet (6), said first, outer annular magnet (8), said second, inner annular magnet (10) and of said 10 second, outer annular magnet (12) is having a direction (Y) corresponding to a direction perpendicular to the annular extension (X) of said magnets; wherein said magnet system comprises a first pole piece arrangement (14), said first pole piece arrangement comprises a first, inner annular pole piece (16) and a first, outer annular pole piece (18), wherein said first, inner annular pole piece (16) is arranged within the interior of said first, outer annular pole 15 piece (18); wherein said first pole piece arrangement (14) is being arranged between said first set of magnets (2) and said second set of magnets (4); wherein the magnetic polarity of said first, inner annular magnet (6) is opposite to the magnetic polarity of said first, outer annular magnet (8); wherein the magnetic polarity of said first, inner annular magnet (6) is opposite to the magnetic polarity of said second, inner annular magnet (10); and wherein the magnetic 20 polarity of said first, outer annular magnet (8) is opposite to the magnetic polarity of said second, outer annular magnet (12); and wherein said first, inner annular magnet (6) and said first, outer annular magnet (8) are having geometries and dimensions so that a first magnet air gap (20) is being present between said first, inner annular magnet (6) and said first, outer annular magnet (8); and/or wherein said second, inner annular magnet (10) and said second 25 outer, annular magnet (12) are having geometries and dimensions so that a second magnet air gap (22) is being present between said second, inner annular magnet (10) and said second outer, annular magnet (12); and/or wherein said said first, inner annular pole piece (16) and said first, outer annular pole piece (18) are having geometries and dimensions so that a first pole piece air gap (24) is being present between said first, inner annular pole piece (16) and 30 said first, outer annular pole piece (18).
    公开号:DK201800678A1
    申请号:DKP201800678
    申请日:2018-10-04
    公开日:2020-04-22
    发明作者:Børresen Michael
    申请人:Upper Level Aps；
    IPC主号:
    专利说明:

    A magnet system for an electromechanical transducer
    Field of the invention
    The present invention relates in general to the field of electromechanical transducers.
    More specifically the present invention relates in a first aspect to a magnet system for an electromechanical transducer.
    In a second aspect the present invention relates to an electromechanical transducer comprising a magnet system according to the first aspect in combination with a coil of an electrically conducting material.
    In a third aspect the present invention relates to a speaker unit comprising an electromechanical transducer according to the second aspect in combination with a diaphragm.
    Background of the invention
    Electromechanical transducers are devices which provides for producing a mechanical movement in a response to an electric signal being provided thereto. Accordingly, electromechanical transducers find application in all sorts of technology where it is desired to control a mechanical actuation with an electric signal.
    Many types of electromechanical transducers exploit the phenomenon that when an electric wire is conducting an electric current in the vicinity of a magnetic field, the wire experiences a force being exerted on the wire.
    As the force exerted on the wire will have a magnitude commensurate with the magnitude of the current flowing in the wire and with the magnitude of the magnetic field, it is clear that for some applications it is desirable to provide the magnetic field as strong as possible.
    One type of technology in which electromechanical transducers have found widely use is the field of loudspeakers.
    A loudspeaker comprises a magnetic system typically comprising one or more magnets in combination with iron elements arranged in a configuration so that an air gap is provided through which magnetic flux from the magnets is directed. In the air gap is arranged a voice coil which is provided with the electric signal to be transformed into sound, optionally via a cross-over filter.
    A diaphragm is connected to the voice coil. As the diaphragm comprises a relatively large area, an electric signal provided to the voice coil will by virtue of induction translate into a movement of the diaphragm, the magnitude of which will mimic the electric signal being
    DK 2018 00678 A1 provided to the voice coil. Thereby the electric signal provided to the voice coil will translate into sonic waves propagating through the air from the diaphragm.
    The design of magnet systems for loudspeakers has for many years adhered to rather conservative concepts.
    These concepts generally follow the following principles. The magnet systems of prior art loudspeakers comprise an annular magnet being arranged between a T-yoke and a top plate. The T-yoke comprises a base plate and a cylindrical extension, extending therefrom. The top plate comprises a circular central hole. In this way an air gap for a voice coil is formed between the cylindrical extension of the T-yoke and the hole in the top plate.
    The annular magnet is having its magnetic polarity aligned in a direction parallel to the extension of the T-yoke. Hereby magnetic flux follows from the magnet to the top plate through the air gap and into the extension of the T-yoke, further through the base plate of the T-yoke and back to the magnet.
    This conservative design current used in the design of the magnet system for loudspeakers in turn suffers from a number of drawbacks.
    One of these drawbacks is that the design itself of the magnet system does not allow attaining a desirable high magnetic flux density in the air gap between the top plate and the pole of the T-yoke. A non-optimum magnetic flux density in the air gap of the pole piece implies a inefficient speaker in the sense that only a small amount of power being supplied to the voice coil translates into mechanical movement of the diaphragm of the speaker.
    Another drawback of the prior art T-yoke type magnet systems is the inherent asymmetric magnetic field encountered in the air gap and especially in the vicinity of the borders of the air gap. Such asymmetry implies various types of undesirably distortion of the movement of the voice coil, in relation to the electric signal supplied thereto.
    Yet another disadvantage of the above type of magnet systems for loudspeakers is that an undesirably high inductance of the voice coil, is encountered in the air gap of the magnet system. Such high inductance leads to a non-linear response of the voice coil in relation to the electric signal supplied thereto.
    Accordingly, a need persists to improve the design of magnet systems for electromechanical transducers and in particular in relation to uses in acoustic drivers for loudspeakers.
    The present invention in its various aspect seeks to meet this need.
    Accordingly, it is an objective of the present invention to provide devices and uses which meet these needs.
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    Brief description of the invention
    These objectives are fulfilled according to the first, the second and the third aspect of the present invention.
    Accordingly, the present invention relates in a first aspect to a magnet system for an electromechanical transducer; wherein said magnet system comprises a first set of magnets and a second set of magnets;
    -wherein said first set of magnets comprises a first, inner annular magnet and a first outer, annular magnet;
    -wherein said second set of magnets comprises a second, inner annular magnet and a second, outer annular magnet;
    -wherein said first, inner annular magnet is arranged in the interior of said first outer annular magnet;
    -wherein said second inner annular magnet is arranged in the interior of said second outer annular magnet;
    -wherein the magnetic polarity in respect of said first, inner annular magnet, said first ,outer annular magnet, said second, inner annular magnet and of said second, outer annular magnet is having a direction corresponding to a direction perpendicular to the annular extension of said magnets;
    -wherein said magnet system comprises a first pole piece arrangement, said first pole piece arrangement comprises a first, inner annular pole piece and a first, outer annular pole piece, wherein said first, inner annular pole piece is arranged within the interior of said first, outer annular pole piece;
    -wherein said first pole piece arrangement is being arranged between said first set of magnets and said second set of magnets;
    -wherein the magnetic polarity of said first, inner annular magnet is opposite to the magnetic polarity of said first, outer annular magnet;
    -wherein the magnetic polarity of said first, inner annular magnet is opposite to the magnetic polarity of said second, inner annular magnet; and
    -wherein the magnetic polarity of said first, outer annular magnet is opposite to the magnetic polarity of said second, outer annular magnet; and
    -wherein said first, inner annular magnet and said first outer, annular magnet are having geometries and dimensions so that a first magnet air gap is being present between said first, inner annular magnet and said first, outer annular magnet; and/or
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    -wherein said second, inner annular magnet and said second, outer annular magnet are having geometries and dimensions so that a second magnet air gap is being present between said second, inner annular magnet and said second, outer annular magnet; and/or
    - wherein said said first, inner annular pole piece and said first, outer annular pole piece are having geometries and dimensions so that a first pole piece air gap is being present between said first, inner annular pole piece and said first, outer annular pole piece
    In a second aspect the present invention relates to an electromechanical transducer comprising a magnet system according to the first aspect of the present invention in combination with one or more coil(s) of an electrically conducting material, wherein said coil(s) is/are being arranged in one or more of the first pole piece air gap and optionally also in a second pole piece air gap, if present, of said magnet system.
    In a third aspect the present invention relates to a speaker unit comprising an electromechanical transducer according to the second aspect of the invention and furthermore comprising a diaphragm, wherein said diaphragm is mechanically coupled to said coil(s).
    The present invention in its various aspects provides for magnet systems, transducers and speaker units which result in a more accurate response in relation to an electric signal being provided, thereby reducing the degree of non-linearity and various types of distortion.
    These advantages of the magnet system according to the invention are particularly profound when the magnet system is used in acoustic drivers for loudspeakers.
    Accordingly, in particularly preferred embodiments the present invention provides for electrodynamic transducers to be used in speaker units and loudspeakers, and having improved properties.
    Brief description of the figures
    Fig. 1 is a cross-sectional view illustrating a prior art magnet system for a loudspeaker unit.
    Fig. 2a is a plan view showing one embodiment of a magnet system according to the first aspect of the present invention comprising two sets of magnets and one pole piece arrangement.
    Fig. 2b is a cross-sectional view illustrating the magnet system of fig. 2a.
    Fig. 3 is a cross-sectional view illustrating another embodiment of a magnet system according to the first aspect of the present invention comprising three sets of magnets and two pole piece arrangements.
    Fig. 4 is a cross sectional view illustrating an electromechanical transducer according to the second aspect of the present invention and comprising the magnet system of fig. 2b.
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    Fig. 5 is a cross sectional view illustrating an electromechanical transducer according to the second aspect of the present invention and comprising the magnet system of fig. 3.
    Fig. 6 is a cross-sectional view illustrating a speaker unit comprising the electromechanical transducer illustrated in Fig. 4.
    Detailed description of the invention
    The first aspect of the present invention
    The present invention relates in a first aspect to a magnet system for an electromechanical transducer; wherein said magnet system comprises a first set of magnets and a second set of magnets;
    -wherein said first set of magnets comprises a first, inner annular magnet and a first outer, annular magnet;
    -wherein said second set of magnets comprises a second, inner annular magnet and a second, outer annular magnet;
    -wherein said first, inner annular magnet is arranged in the interior of said first outer annular magnet;
    -wherein said second inner annular magnet is arranged in the interior of said second outer annular magnet;
    -wherein the magnetic polarity in respect of said first, inner annular magnet, said first, outer annular magnet, said second, inner annular magnet and of said second, outer annular magnet is having a direction corresponding to a direction perpendicular to the annular extension of said magnets;
    -wherein said magnet system comprises a first pole piece arrangement, said first pole piece arrangement comprises a first, inner annular pole piece and a first, outer annular pole piece, wherein said first, inner annular pole piece is arranged within the interior of said first, outer annular pole piece;
    -wherein said first pole piece arrangement is being arranged between said first set of magnets and said second set of magnets;
    -wherein the magnetic polarity of said first, inner annular magnet is opposite to the magnetic polarity of said first, outer annular magnet;
    -wherein the magnetic polarity of said first, inner annular magnet is opposite to the magnetic polarity of said second, inner annular magnet; and
    -wherein the magnetic polarity of said first, outer annular magnet is opposite to the magnetic polarity of said second, outer annular magnet; and
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    -wherein said first, inner annular magnet and said first outer, annular magnet are having geometries and dimensions so that a first magnet air gap is being present between said first, inner annular magnet and said first, outer annular magnet; and/or
    -wherein said second, inner annular magnet and said second, outer annular magnet are having geometries and dimensions so that a second magnet air gap is being present between said second, inner annular magnet and said second, outer annular magnet; and/or
    - wherein said said first, inner annular pole piece and said first, outer annular pole piece are having geometries and dimensions so that a first pole piece air gap is being present between said first, inner annular pole piece and said first, outer annular pole piece.
    Accordingly, the magnet system of the first aspect of the present invention relates to a magnet system comprising a first set of magnets and a second set of magnets and a pole piece arrangement, wherein the pole piece arrangement is sandwiched between the first set of magnets and the second set of magnets. Air gaps are provided between the inner and outer magnets of each set of magnets, and between the inner pole piece and the outer pole piece. In this or these air gaps can be accommodated a coil of an electrically conducting wire, thereby forming a electromechanical transducer.
    The high symmetry of the magnet system provides, in relation to prior art magnet system certain advantages as explained further in sections below.
    In one embodiment of the magnet system according to the first aspect of the present invention, the magnet system is a magnet system for an acoustic driver, such as for a loudspeaker.
    The magnet system of the present invention is particularly well-suited for use in for an acoustic driver, such as in a loudspeaker.
    In one embodiment of the magnet system according to the first aspect of the present invention, the first magnet air gap, said second magnet air gap and/or said first pole piece air gap independently is having an extension in a direction perpendicular to the direction of said magnetic polarities, of 0.1 - 6 mm, such as 0.2 - 5 mm, e.g. 0.3 - 4 mm, such as 0.4 - 5 mm, for example 0.5 - 4 mm, such as 0.6 - 3 mm, such as 0.7 - 2 mm, for example 0.8 - 1 mm.
    Such “radial” extensions of the air gap have proven suitable for the intended purposes of the present invention.
    In one embodiment of the magnet system according to the first aspect of the present invention two or more of the first magnet air gap, the second magnet air gap and/or the first pole piece air gap independently is having an extension, in a direction perpendicular to the direction of said magnetic polarities, of equal magnitude.
    In one embodiment of the magnet system according to the first aspect of the present invention the magnet system comprises fixation means, for fixing, relative to each other, the first, inner annular magnet, the first, outer annular magnet; the second, inner annular magnet, the second,
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    Ί outer annular magnet; the first, inner annular pole piece and the first, outer annular pole piece; wherein the fixation means optionally comprising bolts, nuts, bushings and/or glue.
    Hereby the structural integrity of the pole piece is assured.
    In one embodiment of the magnet system according to the first aspect of the present invention the first, inner annular magnet, the first, outer annular magnet; the second, inner annular magnet and the second, outer annular magnet independently are magnets selected from the group comprising: ferrite magnets, samarium-cobalt magnets, alnico magnets, neodymiumiron-boron magnets or other commercially available types of magnets.
    Such types of magnetic materials have proven beneficial in relation to the present invention.
    In one embodiment of the magnet system according to the first aspect of the present invention the first, inner annular pole piece and the first, outer annular pole piece independently are being made from ferrous or non-ferrous material, such as iron or an iron alloy; or the first, inner annular pole piece and the first, outer annular pole piece independently are being made from a non-ferromagnetic material, such as a non-ferromagnetic metal or alloy; such as copper, aluminium or silver, or an alloy thereof, such as bronze or brass.
    These materials have proved well-suited for use in the magnet system of the invention.
    In one embodiment of the magnet system according to the first aspect of the present invention the first, inner annular magnet, the second, inner annular magnet and the first, inner annular pole piece each independently are having a cylindrical inner surface and/or a cylindrical outer surface.
    Such geometries are common for magnet systems and pole pieces for use in a speaker unit.
    In one embodiment of the magnet system according to the first aspect of the present invention the first, outer annular magnet, the second, outer annular magnet and the first, outer annular pole piece each independently are having a cylindrical inner surface and/or a cylindrical outer surface.
    Such geometries are common for magnet systems and pole pieces for use in a speaker unit.
    In one embodiment of the magnet system according to the first aspect of the present invention the inner surface and/or the outer surface of one or more of the first, inner annular magnet, the second, inner annular magnet; the first, outer annular magnet; the second, outer annular magnet; the first, inner annular pole piece and/or the first, outer annular pole piece is/are having a circular, an elliptical, or a rectangular cross section; or having a cross-section in the form of a rounded rectangle.
    Such geometries are common for magnet systems and pole pieces for use in a speaker unit.
    In one embodiment of the magnet system according to the first aspect of the present invention the first, inner annular magnet is concentrically arranged within the first, outer annular magnet; and/or the second, inner annular magnet is concentrically arranged within the second,
    DK 2018 00678 A1 outer annular magnet; and/or the first, inner annular pole piece is concentrically arranged within said first, outer annular pole piece.
    Such concentrically arrangement may provide for a symmetrical geometry of the corresponding air gaps.
    In one embodiment of the magnet system according to the first aspect of the present invention the and in respect of one or both magnets of the first set of magnets and/or the second set of magnets is having a magnetic flux density, at a pole surface thereof, of 0.1 - 1.4 T, such as 0.2
    - 1.3 T, for example 0.3 - 1.2 T, such as 0.4 - 1.1 T, e.g. 0.5 - 1.0 T, such as 0.6 - 0.9 T or 0.7 - 0.8 T.
    In one embodiment of the magnet system according to the first aspect of the present invention the magnets of said first set of magnets and of the second set of magnets provide a magnetic flux density in said first pole piece air gap of 0.5 - 1.4 T, such as 0.6 - 1.3 T, for example 0.7
    - 1.2 T, e.g. 0.8 - 1.1 T or 0.9 - 1.0 T.
    Such flux densities provide for efficient response of a coil of an electrically conducting material when the coil is accommodated in the first pole piece air gap, such as when used in an electromechanical transducer, such as a speaker unit.
    In one embodiment of the magnet system according to the first aspect of the present invention the maximum extension, in a direction perpendicular to the direction of the magnetic polarity of the magnets, of one or more of the first, inner annular magnet, the second, inner annular magnet; the first, outer annular magnet; the second, outer annular magnet; the first, inner annular pole piece and/or the first, outer annular pole piece independently is/are selected from the ranges: 0.1 - 30 cm, such as 0.2 - 29 cm, e.g. 0.4 - 28 cm, such as 0.6 - 27 cm, such as 0.7 - 26 cm, e.g. 0.8 - 25 cm, such as 0.9 - 24 cm, e.g. 1.0 - 23 cm, such as 1.5 - 22 cm, such as 2 - 21 cm, e.g. 3 - 20 cm, such as 4 - 19 cm, for example 5 - 18 cm or 6 - 17 cm, e.g. 7 16 cm, such as 8 - 15 cm, for example 9- 14 cm, such as 10 - 13 cm or 11 - 12 cm.
    In one embodiment of the magnet system according to the first aspect of the present invention the maximum extension, in a direction parallel to the direction of the magnetic polarity of the magnets of or more of the first, inner annular magnet, the second, inner annular magnet; the first, outer annular magnet; the second, outer annular magnet; the first, inner annular pole piece and/or the first, outer annular pole piece independently is/are selected from the ranges: 0.1 - 20 cm, such as 0.2 - 19 cm, e.g. 0.4 - 18 cm, such as 0.6 - 17 cm, such as 0.7 - 16 cm, e.g. 0.8 - 15 cm, such as 0.9 - 14 cm, e.g. 1.0 - 13 cm, such as 1.5 - 12 cm, such as 2 - 11 cm, e.g. 3 - 10 cm, such as 4 - 9 cm, for example 5 - 8 cm or 6 - 7 cm.
    Such dimensions are for magnet systems and pole pieces for use as an electromechanical transducer, such as for use in a speaker unit.
    In one embodiment of the magnet system according to the first aspect of the present invention the one or more of the first, inner annular magnet, the second, inner annular magnet; the first, outer annular magnet; the second, outer annular magnet independently comprises an array of
    DK 2018 00678 A1 separate magnet entities which collectively make up such a magnet; or comprises a single coherent magnet entity.
    Either of these configurations may equally well be used in the magnet system of the present invention.
    In one embodiment of the magnet system according to the first aspect of the present invention one or more of the first, inner annular pole piece and/or the first outer annular pole piece independently comprises an array of separate pole piece entities which collectively make up such a pole piece; or comprises a single coherent pole piece entity.
    Either of these configurations may equally well be used in the magnet system of the present invention.
    In one embodiment of the magnet system according to the first aspect of the present invention the magnet system, physically and magnetically, is being symmetric in relation to a mirror plane; wherein the mirror plane being perpendicular to the direction of the magnetic polarity of the magnets and is cutting through the first, inner annular pole piece and the first outer annular pole piece.
    In one embodiment of the magnet system according to the first aspect of the present invention one or both of the magnets of the first magnet system or of the second magnet system, or of one or both of the pole pieces of the first pole piece arrangement independently deviates from having an annular character in that one or more slits are being present in those magnet(s) or pole piece(s).
    Each of the slits accordingly will extend through part of the magnet or the pole piece from an outer surface thereof to an inner surface thereof.
    Such geometries of the magnets and the pole pieces may satisfactorily be used in the present invention in its various aspects.
    In one embodiment of the magnet system according to the first aspect of the present invention the magnet system furthermore comprises:
    -a third set of magnets, wherein the third set of magnets comprises a third, inner annular magnet and a third outer, annular magnet, wherein the third, inner annular magnet is being arranged within the interior of the third outer, annular magnet; and
    -a second pole piece arrangement; wherein the second pole piece arrangement comprises a second, inner annular pole piece and a second, outer annular pole piece, wherein the second, inner annular pole piece is being arranged within the interior of the second, outer annular pole piece;
    -wherein the second set of magnets are being arranged between the first pole piece arrangement and the second pole piece arrangement; and
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    -wherein the second pole piece arrangement is being arranged between the second set of magnets and the third set of magnets;
    -wherein the magnetic polarity of the third, inner annular magnet is opposite to the magnetic polarity of the second, inner annular magnet; and
    -wherein the magnetic polarity of the third, outer annular magnet is opposite to the magnetic polarity of the second, outer annular magnet;
    -wherein the third, inner annular magnet and the third outer, annular magnet are having geometries and dimensions so that a third magnet air gap is being present between the third, inner annular magnet and the third outer, annular magnet;
    -wherein the second, inner annular pole piece and the second, outer annular pole piece are having geometries and dimensions so that a second pole piece air gap is being present between the second, inner annular pole piece and the second, outer annular pole piece.
    In one embodiment of the magnet system according to the first aspect of the present invention the features relating to the second, inner annular pole piece and/or the second, outer annular pole piece are as those defined in any of the preceding claims in respect of the first inner annular pole piece and/or the first, outer annular pole piece, respectively.
    Whereas the magnet system of the first aspect of the present invention in its general form represents a pole piece arrangement being “sandwiched” between two magnet systems, the embodiment described above can be interpreted as a “double sandwich” of magnet systems and pole piece arrangement.
    In this embodiment three magnet systems and two pole piece arrangements are present and arranged so that each pole piece arrangement is “sandwiched” between two magnet systems.
    Accordingly, it is clear that features relating to the first inner annular pole piece and/or the first, outer annular pole piece, respectively, may apply equally well to the second, inner annular pole piece and/or the second, outer annular pole piece, respectively.
    In one embodiment of the magnet system according to the first aspect of the present invention the features relating to the third inner, annular magnet (30) and/or the third, outer annular magnet (32) are as those defined in respect of the first inner annular magnet (6) and/or the first, outer annular magnet (8), respectively.
    It is clear that features relating to the third inner, annular magnet and/or the third, outer annular magnet respectively, may apply equally well to the those defined in respect of the first inner annular magnet and/or the first, outer annular magnet, respectively.
    In one embodiment of the magnet system according to the first aspect of the present invention the features relating to mutual relations between the third inner annular magnet, the third outer annular magnet, the second, inner annular pole piece and the second outer annular pole piece, respectively, corresponds to those features relating to mutual relations, as defined in any of
    DK 2018 00678 A1 the preceding claims, between the first, inner annular magnet, the first outer annular magnet, the first, inner annular pole piece and the first outer annular pole piece, respectively.
    Again, due to the symmetric nature of the magnet system, it is clear that these similarities may apply.
    In one embodiment of the magnet system according to the first aspect of the present invention the magnet system, physically but not necessarily magnetically, is being symmetrical in relation to a mirror plane; said mirror plane being perpendicular to the direction of the magnetic polarity of the magnets, is cutting through the second, inner annular magnet and the second, outer annular magnet.
    The second aspect of the present invention
    In a second aspect the present invention related to an electromechanical transducer comprising a magnet system according to the first aspect of the present invention in combination with one or more coil(s) of an electrically conducting material, wherein said coil(s) is/are being arranged in one or more of the first pole piece air gap and optionally also in the second pole piece air gap, if present, of said magnet system.
    In one embodiment of the electromechanical transducer according to the second aspect of the present invention the coil(s) is/are arranged around a tubular coil former, wherein said tubular coil former is being arranged at least partly in one or more of said first magnet air gap, said second magnet air gap, said first pole piece air gap; and optionally also in said third magnet air gap and/or in said second pole piece air gap.
    A coil former provides for guiding the position of the coil in the air gap, thereby aiding in avoiding that the coil(s) move(s) in a radial direction.
    The third aspect of the present invention
    In a third aspect the present invention relates to a speaker unit comprising an electromechanical transducer according to the second aspect of the invention and furthermore comprising a diaphragm, wherein said diaphragm is mechanically coupled to said coil(s).
    In one embodiment of the speaker unit according to the third aspect of the present invention the unit comprising a chassis, wherein the magnet system is being fixed to that chassis, and wherein the diaphragm is being mechanically coupled to the chassis, such as at an outer perimeter of the diaphragm; and wherein the diaphragm, at a distance from the outer perimeter, is being mechanically coupled to the coils, such as via a spider.
    Referring to the figure in order to better illustrating the present invention, Fig. 1 is a crosssectional view of a typical prior art magnet system for an acoustic driver.
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    Fig. 1 shows the prior magnet system 200 comprising a T-yoke 202, a top plate 208 and an annular magnet 210. All the elements making up the prior art magnet system 200 is having a rotational symmetry around the axial axis R.
    The T-yoke comprises a base plate 204 and an axial extension 206. The annular magnet 210 is coaxially arranged around the axial extension 206 of the T-yoke and the top plate 208 is arranged on top of the annular magnet 210. The top plate is comprising a center hole 214 which has a larger diameter than the diameter of the axial extension 206 of the T-yoke 202. This leaves an air gap 212 between the top plate and the upper portion of the T-yoke extension 206 of the T-yoke.
    The polarity of the annular magnet 210 is directed in an axial direction as shown.
    The magnet flux density radiates from the north pole N of the magnet 210 to the top plate where it changes direction and crosses the air gap to the upper portion of the axial extension 206 of the T-yoke 202, from where it continues axially through the axial extension 206 and enters the base plate 202 and extends into the south pole of the magnet 210.
    The air gap 212 is intended for accommodating a voice coil which is to be connected to a diaphragm of the acoustic driver.
    It can be seen in Fig. 1 that from a given rest point of a voice coil accommodated in the air gap 212 the geometry of the magnet system is different in moving in one axial direction in the air gap, compared to a situation in which the voice coil moves in the opposite axial direction.
    Such an asymmetry of the air gap of the prior art magnet system has the consequence that a corresponding asymmetric magnetic flux density is encountered by a voice coil accommodated in the air gap, and this in turn will lead to various types of distorted response of the voice coil in relation to an electric signal supplied thereto. Moreover, such asymmetric magnetic flux density in the air gap will lead to a non-linearity in the voice coil response.
    In more detail this can be explained as follows. For a given frequency supplied to the voice coil being accommodated in the air gap surrounding the axial extension 206 of the T-yoke of the magnet system of a prior art speaker unit, the current flowing in the coil will depend on the axial position of the voice coil (because the inductance decreases when the voice coil is arranged in the air gap, compared to a situation where part of the voice coil has moved out of the air gap). This will lead to a non-linear response of the movement of the voice coil, because the force exerted on the voice coil and originating from the induction taking place will depend on the current flowing in the voice coil.
    Moreover, when the voice coil is moving axially back and forth in the air gap, it will in extreme positions, in which part of the coil approaches or event leaves the air gap, experience different magnetic flux geometries (due to the non-symmetric geometry of the T-yoke magnet system) in the two opposite, extreme positions. This will have as a consequence that when an electrical signal which is symmetric, such as a sine curve is provided to the voice coil the mechanical response of the voice coil which translates into sound waves having an amplitude
    DK 2018 00678 A1 curve which has lost its symmetry due to the non-symmetric flux encountered by the voice coil at the two opposite extreme positions of the voice coil in the air gap. Accordingly, this represents a distortion of the symmetrical electric signal.
    Obviously, also a non-symmetric signal being supplied to the voice coil of the prior art will imply same type of distortion when it is translated into sound waves by the speaker unit comprising the same type of T-yoke magnet system.
    Accordingly, the prior art magnet system comprising a T-yoke, an annular magnet and a top plate represent certain disadvantages, which the present invention seeks to solve.
    Fig. 2a is a plan view illustrating a magnet system of the first aspect of the present invention.
    Fig. 2a shows the magnet system 100 for an electromechanical transducer, comprising a first, inner annular magnet 6 and a first, outer annular magnet 8. The first, inner annular magnet 6 is arranged within the first, outer annular magnet 8.
    The first, inner annular magnet 6 and the first, outer annular magnet 8 make up a first set of magnets 2. Behind the first set of magnets 2 are arranged a first pole piece arrangement 14 and a second set of magnets 4 (these parts are not seen in Fig. 2a).
    It is seen in fig. 2a that a first magnet air gap 20 is arranged between the first, inner annular magnet 6 and the first, outer annular magnet 8. The air gap 20 extends into a second magnet air gap 22 (between two magnets making up the second set of magnets) and into a first pole piece air gap 24 (between two pole pieces making up the first pole piece arrangement).
    Fig. 2b is a cross sectional view illustrating the magnet system of Fig. 2a as seen through the cut A-A.
    Fig. 2b shows the magnet system 100 comprises a first set 2 of magnets and a second set 4 of magnets and comprising a first pole piece arrangement 14.
    The first set 2 of magnets comprises a first, inner annular magnet 6 and a first outer, annular magnet 8.
    Likewise, the second set 4 of magnets comprises a second, inner annular magnet 10 and a second, outer annular magnet 12.
    It is seen in Fig. 2b that the first, inner annular magnet 6 is arranged in the interior of said first outer annular magnet 8, and that the second inner annular magnet 10 is arranged in the interior of said second outer annular magnet 12.
    Fig. 2b also shows the magnetic polarity of the magnets of the first and second set 2,4 of the magnets involved.
    Accordingly, the magnetic polarity in respect of the first, inner annular magnet 6, the first outer, annular magnet 8, the second, inner annular magnet 10 and of the second, outer annular
    DK 2018 00678 A1 magnet 12 is having a direction Y corresponding to a direction perpendicular to the annular extension X of the magnets. That is, the magnetic polarity is directed in an axial direction.
    As mentioned, the magnet system also comprises a first pole piece arrangement 14.
    The first pole piece arrangement 14 comprises a first, inner annular pole piece 16 and a first, outer annular pole piece 18, wherein the first, inner annular pole piece 16 is arranged within the interior of the first, outer annular pole piece 18.
    Moreover, it is seen in Fig. 2b that the first pole piece arrangement 14 is being arranged between the first set of magnets 2 and said second set of magnets 4.
    The magnetic polarity of the first, inner annular magnet 6 is opposite to the magnetic polarity of the first, outer annular magnet 8; the magnetic polarity of the first, inner annular magnet 6 is opposite to the magnetic polarity of the second, inner annular magnet 10; and the magnetic polarity of the first, outer annular magnet 8 is opposite to the magnetic polarity of the second, outer annular magnet 12.
    Hereby also the magnetic polarity of the second, inner annular magnet 10 will be opposite to the magnetic polarity of the second, outer annular magnet 12.
    It is clear that an opposite magnetic polarity in respect of each of the magnets illustrated in Fig. 2b could equally well be applied.
    It is seen in Fig. 2b that the first, inner annular magnet 6 and the first outer, annular magnet 8 are having geometries and dimensions so that a first magnet air gap 20 is being present between the first, inner annular magnet 6 and said first outer, annular magnet 8
    Likewise, the second, inner annular magnet 10 and said second outer, annular magnet 12 are having geometries and dimensions so that a second magnet air gap 22 is being present between the second, inner annular magnet 10 and the second outer, annular magnet 12.
    Moreover, the first, inner annular pole piece 16 and said first, outer annular pole piece 18 are having geometries and dimensions so that a first pole piece air gap 24 is being present between the first, inner annular pole piece 16 and the first, outer annular pole piece 18.
    Mounting guides 26 have been provided during the assembly of the elements making up the magnet system,
    The air gap 24 arranged between the first inner annular pole piece 16 and the first outer, annular pole piece 18 provides for accommodation of a coil of an electrically conducting material, thereby leading to an electromechanical transducer.
    It is seen in Fig. 2b that when accommodating a coil, such as a voice coil, in the first pole piece air gap 24, that coil will encounter the same magnetic properties, originating from the four magnets 6,8,10,12, in that air gap when moving in an axial direction in either of the two axial direction because the magnet system is fully symmetrical around a mirror plane cutting through the first pole piece arrangement.
    DK 2018 00678 A1
    Such symmetry of magnetic properties in the axial direction of an air gap of an electrodynamic transducer is highly desirable when used as an acoustic driver.
    Fig. 4 is a cross-sectional view illustrating an electrodynamic transducer according to the second aspect of the present invention.
    Fig. 4 shows the electrodynamic transducer 300 comprising a magnetic system 100 as illustrated in Fig. 2b. The magnet system 100 is provided with a coil 302 of an electrically conducting material arranged in the air gap 24 located between the first inner annular pole piece 16 and the first outer, annular pole piece 18.
    Fig. 4 shows that the coil 302 has been wound on a coil former 304 for supporting the coil 302.
    In case the coil former 304 is being connected to a diaphragm a speaker unit is formed. This is illustrated in Fig. 6.
    Fig. 6 is a cross-sectional view illustrating a speaker unit according to the third aspect of the present invention.
    Fig. 6 shows the speaker unit 400 comprising the electrodynamic transducer 300 of Fig. 4 which in turn comprises the magnet system 100. The magnet system 100 of the speaker is fastened to a chassis 404 onto which the diaphragm 402 is suspended at an outer perimeter thereof. The coil former 304 of the electrodynamic transducer 300 is attached to the back side of the diaphragm 402 via the spider 306, thereby forming a speaker unit, such as a woofer.
    Fig. 3 is a cross section illustrating an alternative embodiment of the magnet system of the first aspect of the present invention.
    Fig. 3 shows the magnet system 100. The upper part of the magnet system illustrated in Fig. 3 comprising the first set 2 of magnets, the second set 4 of magnets and the first pole piece arrangement 14 is identical to the magnet system illustrated in Fig. 2b.
    In addition to these parts, the magnet system 100 illustrated in Fig. 3 comprises a third set of magnets 28 comprising a third, inner annular magnet 30 and a third outer, annular magnet 32, wherein the third, inner annular magnet 30 is being arranged within the interior of the third outer, annular magnet 32.
    Moreover, it is seen in Fig. 3 that the magnet system 100 comprises a second pole piece arrangement 34 comprising a second, inner annular pole piece 36 and a second, outer annular pole piece 38, wherein the second, inner annular pole piece 36 is being arranged within the interior of said second, outer annular pole piece 38.
    The second set of magnets 4 are being arranged between the first pole piece arrangement 14 and the second pole piece arrangement 34; and the second pole piece arrangement 34 is being arranged between the second set of magnets 4 and the third set of magnets 28.
    DK 2018 00678 A1
    The magnetic polarity of the third, inner annular magnet 30 is opposite to the magnetic polarity of said second, inner annular magnet 10; and the magnetic polarity of the third, outer annular magnet 32 is opposite to the magnetic polarity of the second, outer annular magnet 12.
    The third, inner annular magnet 30 and the third outer, annular magnet 32 are having geometries and dimensions so that a third magnet air gap 40 is being present between the third, inner annular magnet 30 and the third outer, annular magnet 32.
    Likewise, the second, inner annular pole piece 36 and the second, outer annular pole piece 38 are having geometries and dimensions so that a second pole piece air gap 46 is being present between the second, inner annular pole piece 36 and said second, outer annular pole piece 38.
    The air gap 24 arranged between the first inner annular pole piece 16 and the first outer, annular pole piece 18 on the one hand; and the air gap 42 arranged between the second inner annular pole piece 36 and the second outer, annular pole piece 32 on the one hand provide for accommodation of two coils of an electrically conducting material, thereby leading to an electromechanical transducer.
    It is seen in Fig. 3 that when accommodating a first coil, such as a voice coil, in the first pole piece air gap 24, and a second coil in the second air gap 42 these two coils will collectively encounter the same magnetic properties, originating from the six magnets 6,8,10,12,30,32 in these two air gaps 24 and 42 when moving in an axial direction in either of the two axial direction because the magnet system is fully physical symmetrical around a mirror plane cutting through the second set of magnets 4.
    Such symmetry of magnetic properties in the axial direction of air gaps of an electrodynamic transducer is highly desirable when used as an acoustic driver.
    Fig. 5 is a cross-sectional view illustrating an electrodynamic transducer according to the second aspect of the present invention.
    Fig. 5 shows the electrodynamic transducer 300 comprising a magnetic system 100 as illustrated in Fig. 3. The magnet system 100 is provided with a first coil 302 of an electrically conducting material arranged in the air gap 24 located between the first, inner annular pole piece 16 and the first, outer annular pole piece 18.
    The magnet system 100 is moreover provided with a second coil 302 of an electrically conducting material arranged in the air gap 42 located between the second, inner annular pole piece 36 and the second, outer annular pole piece 38.
    Obviously, the phase of the electrical signal supplied to the first coil 302 and the second coil 302, respectively is selected so that the two coils will be moving in concert in the same direction rather than moving in opposite direction in the air gaps 24 and 42 respectively.
    The two coils 302 have been wound on a coil former 304 for supporting the coil 302.
    DK 2018 00678 A1
    Examples
    Example 1 - Concentrating magnetic flux density in air gap
    This example illustrates the ability of the magnet system according to the first aspect of the present invention to provide a considerably increased magnetic flux density in the air gap between the two pole pieces of the first pole piece arrangement.
    Four magnets were used for designing a magnet system according to the first aspect of the present invention.
    Each magnet was of the neodymium-iron-boron type. Each of the four magnets had a cylindrical inner surface and a cylindrical outer surface of circular cross-sections. The magnetic polarity of each magnet was aligned in the axial direction.
    The dimensions of the magnets were as follows:
    The first and second, inner annular magnet had an inner diameter of 30 mm and an outer diameter of 50 mm. The axial extension of these magnets was 15 mm.
    The first and second, outer annular magnet had an outer diameter of 80 mm and an inner diameter of 56 mm. The axial extension of these magnets was 15 mm.
    The first inner and first outer pole piece had radial dimensions corresponding to the magnets and had an axial extension of 12 mm. The pole pieces were made of copper.
    Using a probe (Gauss/Teslameter: BST BST600 Gaussmeter), the magnetic flux density was measured at the surface of the pole of the magnets. The magnetic flux density was measured to be 0.35 Tesla.
    A magnet system having a geometry according to the first aspect of the present invention was manufactured by assembling the four magnets and the two pole pieces into a magnet system entity. The structure of the resulting magnet system was as depicted in Fig. 2a and 2b.
    The same probe was used for measuring the magnetic flux density in the first pole piece air gap (i.e. the air gap being present between the first, inner pole piece and the first outer pole piece). The magnetic flux density was measured to be 1.2 Tesla in this air gap.
    Accordingly, in the magnet system of the present invention, the magnetic flux density has been concentrated into the first pole piece air gap, compared to the magnetic flux density at the surface of the pole of the magnet of a factor > 3.4.
    A high flux density in the air gap of a magnet system provides for a high efficiency of an electromechanical transducer.
    Moreover, in contrast to the prior art magnet systems comprising a T-yoke, an annular magnet and a top plate, the magnet system according to the first aspect of the present invention
    DK 2018 00678 A1 ensures that the magnetic flux variation when moving in an out of the air gap between the pole pieces of the first pole piece arrangement is symmetrical in the two axial directions.
    Hereby, any undesirably properties caused by effects relating to unsymmetrical border conditions at the extreme outer positions of the air gap and the magnetic flux present therein is reduced.
    This is highly appreciated when the magnet system is used in an acoustic driver for a loudspeaker.
    Example 2 - Obtaining an unprecedented low inductance in a coil arranged in the pole piece air gap of the inventive magnet system
    In the magnet system according to the present invention described in Example 1 above, a coil was arranged at a center position in the axial direction of the first pole piece air gap.
    The specifications of the coil were as follows:
    The coil was cylindrical with a circular cross-section and was wound with copper clad wire having a diameter of 0.2 mm. The coil comprises an inner coil and an outer coil. The total number of windings were 40.
    The inductance of the coil in free air was, using a DATS V2 computer program, measured to be 0.45 mH.
    Subsequently, the coil was arranged concentrically in the first pole piece air gap of the magnet system described in Example 1 in order to obtain an electromechanical transducer according to the second aspect of the present invention.
    Using the same DATS V2 computer program with the same settings, the inductance was now measured to 0.05 mH.
    In case the electromechanical transducer is to be used as a speaker unit, such as a driver for a loudspeaker, this low inductance of the coil is highly desirable.
    The low inductance obtained implies that the coil is capable of responding to an electrical signal supplied to it a faster rate with reduced lag, thus leading to a more detailed presentation of the sound generated by the speaker.
    Additionally, the very low inductance also implies lower resonance impedance variation, which in turn results in lower phase angles and impedance variation for the amplifier driving the speaker.
    The inventor of the present invention is not aware of prior art speaker units of similar physical specifications which are having such as low inductance. Rather, to the best of the inventor’s knowledge all prior art speakers of similar physical specifications are having an inductance which is higher by around a factor 10.
    DK 2018 00678 A1
    Another advantage of the inventive magnet system, when used in a speaker unit, is the possibility of manufacturing the inner and outer annular pole pieces of a material having a high thermal conductivity, such as copper or an copper alloy, or silver. Thereby any heat dissipated in the coil accommodated in pole piece air gap can be efficiently be removed.
    As the inner and outer annular pole pieces can be designed with a considerably physical extension in an axial direction and in a direction perpendicular thereto, thereby comprising a considerably mass of a relatively good thermal conductor, very efficient heat sinking properties can be provided to the speaker unit.
    According, in high end audio applications, in which sound quality is of primary importance 10 and in which manufacturing price is secondary, the present invention in its various aspect presents a wide variety of advantages.
    It should be understood that all features and achievements discussed above and in the appended claims in relation to one aspect of the present invention and embodiments thereof apply equally well to the other aspects of the present invention and embodiments thereof.
    DK 2018 00678 A1
    List of reference numerals
    2First set of magnets4Second set of magnets6First, inner annular magnet8First, outer annular magnet10Second, inner annular magnet12Second, outer annular magnet14First pole piece arrangement16First, inner pole piece18First, outer pole piece20First magnet air gap22Second magnet air gap24First pole piece air gap26Mounting guide28Third set of magnets30Third inner, annular magnet32Third outer, annular magnet34Second pole piece arrangement36Second inner annular pole piece38Second outer annular pole piece40Third magnet air gap42Second pole piece air gap100Magnet system according to the present invention200Magnet system according to the prior art202T-yoke of prior art magnet system204Base plate of T-yoke206Center extension of T-yoke208Top plate of prior art magnet system210Annular magnet of prior art magnet system212Air gap for voice coil between top plate and center extension
    DK 2018 00678 A1
    214 Center hole in top plate
    300 Electromechanical transducer according to the present invention
    302 Coil of electrically conduction material
    304 Coil former for supporting coil
    400 Speaker unit
    402 Diaphragm
    404 Chassis of speaker unit
    406 Spider of speaker unit
    N North pole of magnetic polarity
    R Rotational axis of symmetry
    S South pole of magnetic polarity
    X Direction parallel to magnetic polarity of magnets
    Y Direction perpendicular to annular extension of annular magnets
    DK 2018 00678 A1
    权利要求:
    Claims (28)
    [1] Claims
    1. A magnet system (100) for an electromechanical transducer; wherein said magnet system comprises a first set (2) of magnets and a second set (4) of magnets;
    -wherein said first set (2) of magnets comprises a first, inner annular magnet (6) and a first outer, annular magnet (8);
    -wherein said second set (4) of magnets comprises a second, inner annular magnet (10) and a second, outer annular magnet (12);
    -wherein said first, inner annular magnet (6) is arranged in the interior of said first outer annular magnet (8);
    -wherein said second inner annular magnet (10) is arranged in the interior of said second outer annular magnet (12);
    -wherein the magnetic polarity in respect of said first, inner annular magnet (6), said first, outer annular magnet (8), said second, inner annular magnet (10) and of said second, outer annular magnet (12) is having a direction (Y) corresponding to a direction perpendicular to the annular extension (X) of said magnets;
    -wherein said magnet system comprises a first pole piece arrangement (14), said first pole piece arrangement comprises a first, inner annular pole piece (16) and a first, outer annular pole piece (18), wherein said first, inner annular pole piece (16) is arranged within the interior of said first, outer annular pole piece (18);
    -wherein said first pole piece arrangement (14) is being arranged between said first set of magnets (2) and said second set of magnets (4);
    -wherein the magnetic polarity of said first, inner annular magnet (6) is opposite to the magnetic polarity of said first, outer annular magnet (8);
    -wherein the magnetic polarity of said first, inner annular magnet (6) is opposite to the magnetic polarity of said second, inner annular magnet (10); and
    -wherein the magnetic polarity of said first, outer annular magnet (8) is opposite to the magnetic polarity of said second, outer annular magnet (12); and
    -wherein said first, inner annular magnet (6) and said first outer, annular magnet (8) are having geometries and dimensions so that a first magnet air gap (20) is being present between said first, inner annular magnet (6) and said first, outer annular magnet (8); and/or
    -wherein said second, inner annular magnet (10) and said second, outer annular magnet (12) are having geometries and dimensions so that a second magnet air gap (22) is being present between said second, inner annular magnet (10) and said second, outer annular magnet (12); and/or
    DK 2018 00678 A1
    - wherein said said first, inner annular pole piece (16) and said first, outer annular pole piece (18) are having geometries and dimensions so that a first pole piece air gap (24) is being present between said first, inner annular pole piece (16) and said first, outer annular pole piece (18).
    [2] 2. A magnet system (100) according to claim 1, wherein said magnet system is a magnet system for an acoustic driver, such as for a loudspeaker.
    [3] 3. A magnet system (100) according to claim 1 or 2, wherein said first magnet air gap (20), said second magnet air gap (22) and/or said first pole piece air gap (24) independently is having an extension in a direction (X) perpendicular to the direction (Y) of said magnetic polarities, of 0.1 - 6 mm, such as 0.2 - 5 mm, e.g. 0.3 - 4 mm, such as 0.4 - 5 mm, for example 0.5 - 4 mm, such as 0.6 - 3 mm, such as 0.7 - 2 mm, for example 0.8 - 1 mm.
    [4] 4. A magnet system (100) according to any of the claims 1 - 3, wherein two or more of said first magnet air gap (20), said second magnet air gap (22) and/or said first pole piece air gap (24) independently is having an extension, in a direction (X) perpendicular to the direction (Y) of said magnetic polarities, of equal magnitude.
    [5] 5. A magnet system (100) according to any of the claims 1 - 4, wherein said magnet system comprises fixation means, for fixing, relative to each other, said first, inner annular magnet (6), said first, outer annular magnet (8); said second, inner annular magnet (10), said second, outer annular magnet (12); said first, inner annular pole piece (16) and said first, outer annular pole piece (18); said fixation means optionally comprising bolts, nuts, bushings and/or glue.
    [6] 6. A magnet system (100) according to any of the claims 1 - 5, wherein said first, inner annular magnet (6), said first, outer annular magnet (8); said second, inner annular magnet (10) and said second, outer annular magnet (12) independently are magnets selected from the group comprising: ferrite magnets, samarium-cobalt magnets, alnico magnets, neodymiumiron-boron magnets or other commercially available types of magnets.
    [7] 7. A magnet system (100) according to any of the claims 1 - 6, wherein said first, inner annular pole piece (14) and said first, outer annular pole piece (16) independently are being made from ferrous or non-ferrous material, such as iron or an iron alloy; or wherein said first, inner annular pole piece (14) and said first, outer annular pole piece (16) independently are being made from a non-ferromagnetic material, such as a non-ferromagnetic metal or alloy; such as copper, aluminium or silver, or an alloy thereof, such as bronze or brass.
    [8] 8. A magnet system (100) according to any of the claims 1 - 7, wherein said first, inner annular magnet (6), said second, inner annular magnet (10) and said first, inner annular pole piece (16) each independently are having a cylindrical inner surface and/or a cylindrical outer surface.
    [9] 9. A magnet system (100) according to any of the claims 1 - 8, wherein said first, outer annular magnet (8), said second, outer annular magnet (12) and said first, outer annular pole
    DK 2018 00678 A1 piece (18) each independently are having a cylindrical inner surface and/or a cylindrical outer surface.
    [10] 10. A magnet system (100) according to any of the claims 1 - 9, wherein the inner surface and/or the outer surface of one or more of said first, inner annular magnet (6), said second, inner annular magnet (10); said first, outer annular magnet (8); said second, outer annular magnet (12); said first, inner annular pole piece (16) and/or said first, outer annular pole piece (18) is/are having a circular, an elliptical, or a rectangular cross section; or having a crosssection in the form of a rounded rectangle.
    [11] 11. A magnet system (100) according to any of the claims 1 - 10, wherein said first, inner annular magnet (6) is concentrically arranged within said first, outer annular magnet (8); and/or wherein said second, inner annular magnet (10) is concentrically arranged within said second, outer annular magnet (12); and/or wherein said first, inner annular pole piece (16) is concentrically arranged within said first, outer annular pole piece (18).
    [12] 12. A magnet system (100) according to any of the claims 1 - 11, wherein in respect of one or both magnets of the first set of magnets (2) and/or the second set of magnets (4) is having a magnetic flux density, at a pole surface thereof, of 0.1 - 1.4 T, such as 0.2 - 1.3 T, for example 0.3 - 1.2 T, such as 0.4 - 1.1 T, e.g. 0.5 - 1.0 T, such as 0.6 - 0.9 T or 0.7 - 0.8 T.
    [13] 13. A magnet system (100) according to any of the claims 1 - 12, wherein said magnets of said first first set of magnets (2) and said second set of magnets (4) provide a magnetic flux density in said first pole piece air gap (24) of 0.5 - 1.4 T, such as 0.6 - 1.3 T, for example 0.7 - 1.2 T, e.g. 0.8 - 1.1 T or 0.9 - 1.0 T.
    [14] 14. A magnet system (100) according to any of the claims 1 - 13, wherein the maximum extension, in a direction (X) perpendicular to the direction of the magnetic polarity (Y) of said magnets, of one or more of said first, inner annular magnet (6), said second, inner annular magnet (10); said first, outer annular magnet (8); said second, outer annular magnet (12); said first, inner annular pole piece (16) and/or said first, outer annular pole piece (18) independently is/are selected from the ranges: 0.1 - 30 cm, such as 0.2 - 29 cm, e.g. 0.4 - 28 cm, such as 0.6 - 27 cm, such as 0.7 - 26 cm, e.g. 0.8 - 25 cm, such as 0.9 - 24 cm, e.g. 1.0 23 cm, such as 1.5 - 22 cm, such as 2 - 21 cm, e.g. 3 - 20 cm, such as 4 - 19 cm, for example 5 - 18 cm or 6 - 17 cm, e.g. 7 - 16 cm, such as 8 - 15 cm, for example 9- 14 cm, such as 10 13 cm or 11 - 12 cm.
    [15] 15. A magnet system (100) according to any of the claims 1 - 14, wherein the maximum extension, in a direction parallel to the direction (Y) of the magnetic polarity of said magnets, of or more of said first, inner annular magnet (6), said second, inner annular magnet (10); said first, outer annular magnet (8); said second, outer annular magnet (12); said first, inner annular pole piece (16) and/or said first, outer annular pole piece (18) independently is/are selected from the ranges: 0.1 - 20 cm, such as 0.2 - 19 cm, e.g. 0.4 - 18 cm, such as 0.6 - 17 cm, such as 0.7 - 16 cm, e.g. 0.8 - 15 cm, such as 0.9 - 14 cm, e.g. 1.0 - 13 cm, such as 1.5 12 cm, such as 2 - 11 cm, e.g. 3 - 10 cm, such as 4 - 9 cm, for example 5 - 8 cm or 6 - 7 cm.
    DK 2018 00678 A1
    [16] 16. A magnet system (100) according to any of the claims 1 - 15, wherein one or more of said first, inner annular magnet (6), said second, inner annular magnet (10); said first, outer annular magnet (8); said second, outer annular magnet (12) independently comprises an array of separate magnet entities which collectively make up such a magnet; or comprises a single coherent magnet entity.
    [17] 17. A magnet system (100) according to any of the claims 1 - 16, wherein of one or more of said first, inner annular pole piece (16) and/or said first outer annular pole piece (18) independently comprises an array of separate pole piece entities which collectively make up such a pole piece; or comprises a single coherent pole piece entity.
    [18] 18. A magnet system (100) according to any of the claims 1 - 17, wherein said magnet system, physically and magnetically, is being symmetric in relation to a mirror plane; said mirror plane being perpendicular to the direction (Y) of the magnetic polarity of the magnets (6,8,10,12) and is cutting through said first, inner annular pole piece (16) and said first outer annular pole piece (18).
    [19] 19. A magnet system (100) according to any of the claims 1 - 18, wherein one or both of the magnets of the first magnet system (2) or of the second magnet system (4), or of one or both of the pole pieces of the first pole piece arrangement (14) independently deviates from having an annular character in that one or more slits are being present in said magnet(s) (6,8,10,12) or pole piece(s) (16,18).
    [20] 20. A magnet system (100) according to any of the preceding claims, wherein said magnet system furthermore comprises:
    -a third set of magnets (28), wherein said third set of magnets comprises a third, inner annular magnet (30) and a third outer, annular magnet (32), wherein said third, inner annular magnet (30) is being arranged within the interior of said third outer, annular magnet (32); and
    -a second pole piece arrangement (34); said second pole piece arrangement comprises a second, inner annular pole piece (36) and a second, outer annular pole piece (38), wherein said second, inner annular pole piece (36) is being arranged within the interior of said second, outer annular pole piece (38);
    -wherein said second set of magnets (4) are being arranged between said first pole piece arrangement (14) and said second pole piece arrangement (34); and
    -wherein said second pole piece arrangement (34) is being arranged between said second set of magnets (4) and said third set of magnets (28);
    -wherein the magnetic polarity of said third, inner annular magnet (30) is opposite to the magnetic polarity of said second, inner annular magnet (10); and
    -wherein the magnetic polarity of said third, outer annular magnet (32) is opposite to the magnetic polarity of said second, outer annular magnet (12);
    DK 2018 00678 A1
    -wherein said third, inner annular magnet (30) and said third outer, annular magnet (32) are having geometries and dimensions so that a third magnet air gap (40) is being present between said third, inner annular magnet (30) and said third outer, annular magnet (32);
    -wherein said second, inner annular pole piece (36) and said second, outer annular pole piece (38) are having geometries and dimensions so that a second pole piece air gap (42) is being present between said second, inner annular pole piece (36) and said second, outer annular pole piece (38).
    [21] 21. A magnet system (100) according to claim 20, wherein the features relating to the second, inner annular pole piece (36) and/or the second, outer annular pole piece (38) are as those defined in any of the preceding claims in respect of the first inner annular pole piece (16) and/or the first, outer annular pole piece (18), respectively.
    [22] 22. A magnet system (100) according to claim 20 or 21, wherein the features relating to the third inner, annular magnet (30) and/or the third, outer annular magnet (32) are as those defined in respect of the first inner annular magnet (6) and/or the first, outer annular magnet (8), respectively.
    [23] 23. A magnet system (100) according to any of the claims 20 - 22, wherein features relating to mutual relations between the third inner annular magnet (30), the third outer annular magnet (32), the second, inner annular pole piece (36) and the second outer annular pole piece (38), respectively, corresponds to those features relating to mutual relations, as defined in any of the preceding claims, between the first, inner annular magnet (6), the first outer annular magnet (8), the first, inner annular pole piece (16) and the first outer annular pole piece (18), respectively.
    [24] 24. A magnet system (100) according to any of the claims 20 - 23, wherein said magnet system, physically but not necessarily magnetically, is being symmetrical in relation to a mirror plane; said mirror plane being perpendicular to the direction (Y) of the magnetic polarity of the magnets (6,8,10,12,30,32) and is cutting through the second, inner annular magnet (10) and the second, outer annular magnet (12).
    [25] 25. An electromechanical transducer (300) comprising a magnet system (100) according to any of the preceding claims in combination with one or more coils (302) of an electrically conducting material, wherein said coil(s) is/are being arranged in one or more of the first pole piece air gap (24) and optionally also in the second pole piece air gap (42), if present, of said magnet system (100).
    [26] 26. An electromechanical transducer (300) according to claim 25, wherein said coil(s) (30) is/are arranged around a tubular coil former (304), wherein said tubular coil former (304) is being arranged at least partly in one or more of said first magnet air gap (20), said second magnet air gap (22), said first pole piece air gap (24); and optionally also in said third magnet air gap (40) and/or in said second pole piece air gap (42).
    DK 2018 00678 A1
    [27] 27. A speaker unit (400) comprising an electromechanical transducer (300) according to claim 25 or 26 furthermore comprising a diaphragm (402), wherein said diaphragm is mechanically coupled to said coil(s) (302).
    [28] 28. A speaker unit (400) according to claim 27, furthermore comprising a chassis (404),
    5 wherein said magnet system (100) is being fixed to said chassis, wherein said diaphragm (402) is being mechanically coupled to said chassis (404), such as at an outer perimeter of said diaphragm; and wherein said diaphragm at a distance from said outer perimeter is being mechanically coupled to said coil(s), such as via a spider.
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    同族专利:
    公开号 | 公开日
    EP3634013A1|2020-04-08|
    US10993035B2|2021-04-27|
    DK180111B1|2020-05-06|
    US20200112793A1|2020-04-09|
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    法律状态:
    2020-04-22| PAT| Application published|Effective date: 20200405 |
    2020-05-06| PME| Patent granted|Effective date: 20200506 |
    优先权:
    申请号 | 申请日 | 专利标题
    DKPA201800678A|DK180111B1|2018-10-04|2018-10-04|A magnet system for an electromechanical transducer|DKPA201800678A| DK180111B1|2018-10-04|2018-10-04|A magnet system for an electromechanical transducer|
    EP19198847.6A| EP3634013A1|2018-10-04|2019-09-23|A magnet system for an electromechanical transducer|
    US16/593,464| US10993035B2|2018-10-04|2019-10-04|Magnet system for an electromechanical transducer|
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