Drive for a loudspeaker

Abstract

Drive for a loudspeaker, preferably planar loudspeaker, comprising a first pole piece (10), a second pole piece (12), a coil (14) arranged between the first pole piece (10) and the second pole piece (12), a first main magnet (20), a second main magnet (22), a third main magnet (26), and a fourth main magnet (28), wherein the first main magnet (20) and the second main magnet (22) are arranged on the first pole piece (10), and wherein the third main magnet (26) and the fourth main magnet (28) are arranged on the second pole piece (12), wherein the first main magnet (20) and the second main magnet (22) are oppositely polarized to each other, and the third main magnet (26) is arranged opposite the first main magnet (20) and is polarized opposite to the first main magnet (20) with respect to the coil (14), and the fourth main magnet (28) is arranged opposite the second main magnet (22) and is polarized opposite to the second main magnet (22) with respect to the coil (14).

Description

The invention relates to a drive for a loudspeaker, preferably planar loudspeakers.DE 10 2018 124 261 A1 discloses a planar loudspeaker which comprises a planar sound panel and a drive unit for driving the sound panel. The drive unit has a plate-shaped coil carrier with a coil formed thereon and a magnetic device. The coil carrier is arranged in a gap between two magnet units of the magnet device.However, the magnetic device has the disadvantage that the magnetic field generated is partly inhomogeneous.It is therefore an object of the invention to provide a drive for a loudspeaker in which the magnetic field generated is as homogeneous as possible.This object is achieved by the subject matter having the features of claim 1.According to the invention, the drive is suitable for a loudspeaker or can be used for this purpose.The loudspeaker can preferably be a planar loudspeaker, that is to say a flat loudspeaker.The drive has a first pole shoe, a second pole shoe and a coil arranged between the first pole shoe and the second pole shoe.The first pole shoe and / or the second pole shoe can have at least one chamfer and / or step on the outer side, for example.Preferably, the first pole shoe and / or the second pole shoe can have fastening holes. This enables fastening to a fastening device.The pole shoes can preferably comprise or consist of a ferromagnetic material, for example a metal material, e.g. steel.The thickness of the pole shoes can be, for example, between 1 mm and 20 mm, preferably between 5 mm and 10 mm, for example 6 mm.Preferably, the first pole shoe and / or the second pole shoe are each formed in one piece.Alternatively, these can be constructed in several parts, since the thickness of the pole shoe material is required for magnetic reasons only in the vicinity of the intermediate magnets. Weight can thereby be saved. However, one limit here represents the rigidity of the pole shoes, since the reluctance force leads to severe deformations. However, the stiffness can also be produced with less material by a skillful selection of the geometry.The coil is preferably flat. For example, the coil may have a width between 1 mm and 10 mm, e.g. 4 mm.The coil can preferably have at least one winding, wherein the winding can extend around a coil core.An outer side of the winding opposite the coil core can have, for example, a fastening region for fastening to the loudspeaker. Preferably, the coil is fastened to the loudspeaker exclusively via this fastening region.The winding can thus be fastened, for example glued, directly to the loudspeaker, for example a membrane and / or a centring device or a holder of the centring device.A coil carrier is preferably not provided here.The winding can be configured, for example, in the form of a strip and / or have a rectangular cross-sectional area.For example, the winding comprises or consists of an aluminum material and / or a copper material.Preferably, the winding further comprises an insulation layer, preferably an efloxacin layer and / or an adhesive lacquer layer.Preferably, the winding is made of an anodized aluminum strip. The efloxacin layer can have a thickness of between 1 μm and 10 μm, for example 4 μm, for example. The eloxat layer electrically isolates turns lying one above the other from one another.The coil core can comprise or consist of air and / or a, preferably glass fiber-reinforced, plastic material, for example.In the case of a coil core made of air, therefore, no fixed coil core at all is provided to some extent. In this case, a strong connecting means can be helpful, for example, which ensures that the coil remains in the desired shape.The drive has a first main magnet, a second main magnet, a third main magnet and a fourth main magnet. In addition, further main magnets can optionally be provided.The main magnets can preferably be neodymium magnets.Preferably, the first main magnet, the second main magnet, the third main magnet and / or the fourth main magnet can be of the same size and / or-apart from the polarity-of the same construction.For example, the main magnets may have mounting holes. These enable fastening to the pole shoes.Preferably, the magnets can be screwed and / or riveted to the pole shoes. For this purpose, countersunk rivets can be used, for example.The first main magnet and the second main magnet are arranged on the first pole shoe, while the third main magnet and the fourth main magnet are arranged on the second pole shoe.Preferably, the first main magnet and the second main magnet are arranged, for example, directly, next to one another and / or parallel to one another.Accordingly, the third main magnet and the fourth main magnet can be arranged, for example, directly, next to one another and / or parallel to one another.The first main magnet and the second main magnet are polarized opposite to each other.Polarity or magnetization is understood here to mean the arrangement of the north and south poles.Preferably, the first main magnet and the second main magnet are oppositely poled to each other in the direction of the coil. Thus, in one main magnet, the south pole is directed in the direction of the coil and in the other main magnet, the north pole.The third main magnet is disposed opposite the first main magnet and is oppositely poled with respect to the coil to the first main magnet.If, for example, the north pole of the first main magnet points toward the coil, the south pole of the third main magnet points toward the coil. If, on the other hand, the south pole of the first main magnet points toward the coil, the north pole of the third main magnet points toward the coil.The fourth main magnet is disposed opposite the second main magnet and is oppositely poled with respect to the coil to the second main magnet.If, for example, the south pole of the second main magnet points toward the coil, the north pole of the fourth main magnet points toward the coil. If, on the other hand, the north pole of the second main magnet points toward the coil, the south pole of the fourth main magnet points toward the coil.Preferably, the third main magnet and the fourth main magnet are polarized in opposite directions to each other.The first main magnet, the second main magnet, the third main magnet and / or the fourth main magnet is preferably poled or magnetized in the direction of the normal vector of the coil. One pole of a main magnet is thus facing the coil and the other pole of the main magnet is facing away from the coil.The magnets can preferably be separate magnets.Alternatively, the first main magnet, the second main magnet and, if appropriate, an optional first intermediate magnet can be designed as a one-piece magnet with corresponding polarity. Accordingly, the third main magnet, the fourth main magnet and, if appropriate, an optional second intermediate magnet can also be designed as a one-piece magnet with corresponding polarity.Overall, for example, a sandwich-like construction of the drive can result:From top to bottom or from left to right, the first pole shoe can be provided first. The first and second main magnets are then connected. The coil now follows. Next, the third and fourth main magnets are provided. This is followed by the second pole shoe.The components are preferably oriented parallel to one another.The magnetic field of the main magnets acts on the coil. The main magnets are arranged in such a way that the scalar product of a normal vector of a coil surface and a magnetic flux density in the coil is positive in one section of the coil and negative in another section of the coil.The main magnets preferably form an annular magnetic field by the two pole shoes and the two air gaps between the main magnets and the coil.The pole shoes preferably form a magnetic short circuit between the rear sides of the main magnets.The drive according to the invention leads to an extremely homogeneous magnetic field in the air gap and to minimal stray losses, since almost the entire magnetic flux runs through the air gap.Steel is usually used for loudspeakers in order to concentrate the magnetic field of neodymium magnets with a magnetic flux density of approximately 1 Tesla to the saturation value of steel of roughly approximately 2 Tesla in the air gap.In the conventional embodiment with two magnets at an angle of 90° to the air gap and relatively wide air gaps, however, there are immense stray losses because with wide magnets a partial magnetic circuit is formed which directly connects the north and south poles at the outer edge of the magnets through the air without passing through the air gap at all.In addition, a magnetic field is formed in the air gap, which magnetic field is not situated for the most part at an angle of 90° to the coil and thus does not contribute to the generation of force in the preferred direction.Simulations have shown that a higher force factor can be achieved by the enormous homogeneity of the magnetic field despite the absence of focusing with the drive according to the invention.Furthermore, in conventional embodiments of the magnetic circuit with two magnets at 90° angle to the air gap, the width of the drive is approximately proportional to the maximum stroke of the coil. With a narrow diaphragm, an extremely large stroke is required to achieve the necessary volume displacement (stroke x radiating surface) for the low-frequency range, so that a conventional magnetic circuit would be wider than the bead of the loudspeaker. However, such loudspeakers cannot be inserted into narrow housings, as are provided for planar loudspeakers. In the drive according to the invention, the additional drive width per additional stroke is smaller by approximately a factor of four.The drive according to the invention is extremely flat overall and is therefore most suitable for use in planar loudspeakers.In contrast to conventional drives, the weight can be reduced considerably. Thus, for example, half of the material, e.g. the steel, for the pole shoes can be saved.In conventional drives, the pole shoes are arranged directly next to the coil, which leads to non-linear distortions in the upper frequency range of the loudspeaker. In the drive according to the invention, the distance between the pole shoes and the coil is significantly greater, which greatly weakens this effect.At high currents, the coil is attracted by the pole shoes with the reluctance force. The force is proportional to the current in the square and strongly dependent on the distance between the coil and the pole shoes and / or on the volume of the pole shoe. This leads, for example, to non-linear distortions.In the case of high-performance loudspeaker drives, this effect has hitherto either been accepted or can only be reduced with great effort. In the drive according to the invention, the distance between the coil and the pole shoes is in any case comparatively large, so that only a low reluctance force occurs even at high currents.The drive according to the invention preferably does not comprise any milling, turning and / or casting and can be produced completely from stamped parts and / or laser parts. As a result, when embodied as laser parts, there is no tool costs, very little waste material and / or very low piece costs.Further developments of the invention can also be taken from the dependent claims, the description and the accompanying drawings.According to one embodiment, a first intermediate magnet is provided between the first main magnet and the second main magnet, which is oriented at right angles to the first main magnet.Between the third main magnet and the fourth main magnet, a second intermediate magnet is provided, which is oriented at right angles to the third main magnet.The intermediate magnets can preferably be neodymium magnets.Preferably, no fastening holes are necessary for the intermediate magnets. Thus, due to the magnetic forces acting, these are pressed by themselves against the pole shoes.The second intermediate magnet is arranged opposite the first intermediate magnet and is polarized opposite the first intermediate magnet with respect to the coil.The first intermediate magnet and / or the second intermediate magnet is preferably poled or magnetized at right angles to the normal vector of the coil. The lateral end faces of the north and south poles thus face the coil.The intermediate magnets preferably concentrate the magnetic field and / or prevent magnetic return flow in undesired directions. For example, the intermediate magnets enable the pole shoes to be made thinner.Thus, the magnetic flux is greatest in the pole shoes parallel to the central magnets. The pole shoes are preferably dimensioned in such a way that the material, for example the steel, at this point reaches saturation just as well.The intermediate magnets deform the magnetic field in such a way that the volume integral is maximized in the air gap in the coil via the cross product of current density vector and magnetic flux density. Without the intermediate magnets, the main magnets would form a magnetic field in the center of the pole shoe which runs across the air gap at the location of the intermediate magnets and can be used less for generating force with the coil.According to a further embodiment, the first intermediate magnet is smaller than the first main magnet and / or the second main magnet.The second intermediate magnet is smaller than the third main magnet and / or the fourth main magnet.According to a further embodiment, the coil is longer than the first main magnet, the second main magnet, the third main magnet and / or the fourth main magnet.The coil thus protrudes longitudinally over at least one main magnet, preferably over all main magnets.According to a further embodiment, the first pole shoe is longer than the first main magnet and / or the second main magnet.Preferably, the first and second main magnets are shorter than the first pole shoe.According to a further embodiment, the second pole shoe is longer than the third main magnet and / or the fourth main magnet.Preferably, the third and fourth main magnets are shorter than the second pole shoe.For example, the first pole shoe and the second pole shoe can be of identical length and / or of identical construction.According to a further embodiment, the first main magnet and / or the second main magnet protrudes laterally beyond the first pole shoe.Preferably, the total width of the first main magnet and of the second main magnet, optionally together with the first intermediate magnet, is greater than the width of the first pole shoe.According to a further embodiment, the third main magnet and / or the fourth main magnet protrudes laterally beyond the second pole shoe.Preferably, the total width of the third main magnet and of the fourth main magnet, optionally together with the second intermediate magnet, is greater than the width of the second pole shoe.The pole shoes are formed narrower than the main magnets to increase the magnetic resistance from the front of the main magnets to the back of the main magnets and maximize the magnetic flux through the air gap.According to a further embodiment, a common fastening device is provided for the first pole shoe and the second pole shoe.For example, the pole shoes can be screwed and / or riveted to the fastening device. For this purpose, countersunk rivets can be used, for example.The pole shoes are held apart by the fastening device, preferably behind and / or in front of the main magnets.Optionally, a feeler gauge band for distance adjustment can be provided between the fastening device and the pole shoes.Preferably, the fastening device can have at least one fastening recess for fastening to a loudspeaker basket.Alternatively or additionally, the fastening device can have at least one fastening hole for fastening a solder plate, on which a stranded wire of the coil is connected to a wire.According to a further embodiment, the fastening device comprises a square tube or is designed as a square tube.The square tube can preferably comprise or consist of a metal material, for example aluminum.All aspects, embodiments and features of the invention described here can be combined with one another, preferably also separately from the specific configuration in the context of which they are mentioned. Preferably, all the subjects of the dependent claims can be combined with one another and with the subject of the independent claim.The invention is described below by way of example with reference to the drawings. The following are shown: FIG. 1 is a perspective view of an embodiment of a drive according to the invention, FIG. 2 is a sectional view (longitudinal) of the drive according to FIG. 1, and FIG. 3 is a sectional view (transverse) of the drive according to FIG. 1.First, it should be noted that the illustrated embodiments are merely exemplary in nature. Thus, individual features can be realized not only in the combination shown, but also alone or in other technically meaningful combinations. For example, the features of one embodiment can be combined with features of another embodiment as desired. The intermediate magnets are purely optional.If a figure contains a reference sign which is not explained in the directly associated text of the description, reference is made to the corresponding preceding or following explanations in the description of the figures. Thus, the same reference numerals are used for identical or comparable components in the figures and these are not explained again.FIG. 1 shows a drive for a loudspeaker, preferably a planar loudspeaker, having a first pole shoe 10 and a second pole shoe 12.A coil 14 is arranged between the first pole shoe 10 and the second pole shoe 12.The first pole shoe 10 and the second pole shoe 12 are fastened to fastening devices 16, which are designed as square tubes.For this purpose, the pole shoes 10, 12 have fastening holes 18. Further fastening holes 18 serve for fastening the main magnets 20, 22.As can be seen in FIG. 2, a first main magnet 20 and a second main magnet 22 are arranged on the first pole shoe 10.The thickness of the pole shoes 10, 12 is preferably at least 0.3 times the height of the main magnets 20, 22.Preferably, the height of the main magnets 20, 22 is greater than the thickness thereof.The first main magnet 20 and the second main magnet 22 may have attachment holes 18 for attachment to the first pole shoe 10.A first intermediate magnet 24 is provided between the main magnets 20, 22.FIG. 3 also shows a third main magnet 26, a fourth main magnet 28 and a second intermediate magnet 30 arranged therebetween. These magnets 26, 28, 30 are arranged on the second pole shoe 12.The first main magnet 20 and the second main magnet 22 are polarized in opposite directions to one another, as is illustrated with the north poles N and south poles S (in principle, all poles can also be interchanged in each case).The third main magnet 26 is arranged opposite the first main magnet 20 and is polarized opposite the first main magnet 20 with respect to the coil 14.The fourth main magnet 28 is arranged opposite the second main magnet 22 and is polarized opposite the second main magnet 22 with respect to the coil 14.The first intermediate magnet 24 is oriented at right angles to the first main magnet 20, while the second intermediate magnet 30 is oriented at right angles to the third main magnet 26.The second intermediate magnet 30 is arranged opposite the first intermediate magnet 24 and is polarized opposite the first intermediate magnet 24 with respect to the coil 14.List of reference characters10 first pole shoe 12 second pole shoe 14 coil 16 fastening device, square tube 18 fastening hole 20 first main magnet 22 second main magnet 24 first intermediate magnet 26 third main magnet 28 fourth main magnet 30 second intermediate magnetReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2018 124 261 A1

[0002]

Claims

Drive for a loudspeaker, preferably planar loudspeaker, having a first pole shoe (10), a second pole shoe (12), a coil (14) arranged between the first pole shoe (10) and the second pole shoe (12), a first main magnet (20), a second main magnet (22), a third main magnet (26), and a fourth main magnet (28), wherein the first main magnet (20) and the second main magnet (22) are arranged on the first pole shoe (10), and wherein the third main magnet (26) and the fourth main magnet (28) are arranged on the second pole shoe (12), wherein the first main magnet (20) and the second main magnet (22) are polarized opposite to one another, and the third main magnet (26) is arranged opposite the first main magnet (20) and is polarized opposite to the first main magnet (20) with respect to the coil (14), and the fourth main magnet (28) is arranged opposite the second main magnet (22) and is polarized opposite the second main magnet (22) with respect to the coil (14).Drive according to Claim 1, characterized in that a first intermediate magnet (24) is provided between the first main magnet (20) and the second main magnet (22), said first intermediate magnet being oriented at right angles to the first main magnet (20), and in that a second intermediate magnet (30) is provided between the third main magnet (26) and the fourth main magnet (28), said second intermediate magnet (30) being oriented at right angles to the third main magnet (26), the second intermediate magnet (30) being arranged opposite the first intermediate magnet (24) and being polarized opposite the first intermediate magnet (24) with respect to the coil (14).Drive according to Claim 1 or 2, characterized in that the first intermediate magnet (24) is smaller than the first main magnet (20) and / or the second main magnet (22), and / or in that the second intermediate magnet (30) is smaller than the third main magnet (26) and / or the fourth main magnet (28).Drive according to one of the preceding claims, characterized in that the coil (14) is longer than the first main magnet (20), the second main magnet (22), the third main magnet (26) and / or the fourth main magnet (28).Drive according to one of the preceding claims, characterized in that the first pole shoe (10) is longer than the first main magnet (20) and / or the second main magnet (22).Drive according to one of the preceding claims, characterized in that the second pole shoe (12) is longer than the third main magnet (26) and / or the fourth main magnet (28).Drive according to one of the preceding claims, characterized in that the first main magnet (20) and / or the second main magnet (22) projects laterally beyond the first pole shoe (10).Drive according to one of the preceding claims, characterized in that the third main magnet (26) and / or the fourth main magnet (28) projects laterally beyond the second pole shoe.Drive according to one of the preceding claims, characterized in that a common fastening device (16) is provided for the first pole shoe (10) and the second pole shoe (12).Drive according to claim 9, characterised in that the fastening device comprises a square tube (16) or is designed as a square tube (16).

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