Improved multi-magnet electroacoustic transducer and electroacoustic system

Abstract

The present invention relates to an improved multi-magnet electroacoustic transducer and an electroacoustic system. An electroacoustic transducer (1) is disclosed, comprising: a frame and / or a housing; a diaphragm; a magnetic circuit system comprising a plurality of central magnets having different magnetic orientations; and a voice coil device having a plurality of voice coils arranged to be movable in an offset direction relative to the magnetic circuit system. The ratio #imgabs0# is lower than 1, wherein w g Represents the average width of all magnetic gaps in the magnetic circuit system, A g It represents the sum of all magnetic gap areas in the magnetic circuit system, h m represents the average height of the central magnet, A m The invention relates to an electroacoustic system comprising an electrodynamic acoustic transducer (1) of the above-mentioned kind and a control circuit (CC) connected to a voice coil device.

Description

Technical Field

[0001] The present invention relates to an electrodynamic acoustic transducer, which includes: a frame and / or a shell; a diaphragm fixed to the frame or the shell; a magnetic circuit system; and a voice coil device. The magnetic circuit system has a plurality of central magnets, the plurality of central magnets having different magnetic orientations, each of the plurality of central magnets including: a central top plate arranged adjacent to one of the central magnets; a common bottom plate arranged adjacent to the central magnet and opposite to the central top plate; and an outer magnetic circuit region surrounding the central magnet and the central top plate, wherein magnetic gaps are formed between the central top plates and between the central top plate and the outer magnetic circuit region. The voice coil device has a plurality of voice coils attached to a diaphragm and arranged to be movable in an offset direction relative to a magnetic circuit system, wherein each voice coil comprises an annular-shaped electrical conductor extending around a separate voice coil axis in an annular section, wherein the voice coil axis is parallel to the offset direction, wherein the magnetic circuit system is designed to generate a magnetic field transverse to the conductors of the voice coils in the annular section, and wherein each voice coil surrounds a top plate of the magnetic circuit system. Furthermore, the present invention relates to an electroacoustic system comprising an electrodynamic acoustic transducer of the above-mentioned kind and a control circuit of a voice coil device connected to the electrodynamic acoustic transducer. Background Art

[0002] Such electrodynamic acoustic transducers are generally known in the prior art. For example, US 2020 / 0045451 A1 discloses a loudspeaker comprising a basin frame having a receiving space, a vibration system arranged at the basin frame, and a magnetic circuit system configured to drive the vibration system to generate sound by vibration. The vibration system comprises a diaphragm whose outer edge is fixedly held by the basin frame and a voice coil configured to drive the diaphragm to vibrate. The voice coil comprises a first voice coil and a second voice coil fixedly connected to the first voice coil, wherein the first voice coil and the second voice coil are arranged in parallel and symmetrically. The voice coil is integrally wound, and the winding direction of the first voice coil is opposite to the winding direction of the second voice coil. The loudspeaker improves the utilization rate of the magnetic field, provides a better vibration effect and reduces the resonance frequency.

[0003] While the described loudspeakers offer some advantages over other designs, there is still room for improvement in the overall performance of electrodynamic acoustic transducers. Summary of the invention

[0004] Therefore, the object of the present invention is to overcome the disadvantages of the prior art and to provide an improved electrodynamic acoustic transducer and an improved electroacoustic system. In particular, the overall performance of the electrodynamic acoustic transducer and the electroacoustic system should be improved.

[0005] The problem solved by the invention is that of a transducer system as defined in the opening paragraph, wherein the ratio Below 1, where

[0006] -w g represents the average width of all magnetic gaps in the magnetic circuit system, which is the average of the diameters of virtual circles inscribed in the magnetic gaps between the center top plates and the magnetic gaps between the center top plates and the outer magnetic circuit area, where the axis of the virtual circle is parallel to the offset direction, where,

[0007] -A g It represents the sum of all magnetic gap areas in the magnetic circuit system. The magnetic gap area is the average height h of the center top plate measured in the direction parallel to the offset direction. tp Multiply by the magnetic gap length l g , magnetic gap length l g is the total length of the magnetic gap centerline connecting the centers of the virtual circles, where,

[0008] -h m represents the average height of the central magnet measured in a direction parallel to the offset direction, and wherein,

[0009] -A m Represents the total area of ​​the central magnet when viewed in a direction parallel to the offset direction.

[0010] Through the above measures, many advantages are obtained. In detail:

[0011] -The voice coil arrangement forms a kind of rib on the back side of the rigid diaphragm part and in particular in its middle region. This is why the rigid diaphragm part does not deform so much when the electrodynamic acoustic transducer is deflected. The voice coils therefore serve a dual function. Firstly, they are part of the driver for the electrodynamic acoustic transducer and secondly, they reinforce the rigid diaphragm part essentially at no cost, since the voice coil is required for the drive anyway. On the other hand, this does also mean that the rigid diaphragm part can be made lighter, which has a positive effect on the frequency response of the electrodynamic acoustic transducer. This effect occurs in particular when the rib formed by the voice coil arrangement extends along a long extension of the rigid diaphragm part, since the rigid diaphragm part is more susceptible to bending about a short axis than about a long axis.

[0012] - Improved magnetic permeability and thermal operating point of the electrodynamic acoustic transducer, thereby improving the overall acoustic performance, especially in terms of efficiency and sensitivity of the electrodynamic acoustic transducer.

[0013] - The cooling of the electrodynamic acoustic transducer is improved, since the surface of the voice coil arrangement is significantly increased compared to known configurations. Thus, higher output powers can be obtained for small electrodynamic acoustic transducers.

[0014] - Reduced magnetic stray fields compared to designs with only one central magnet.

[0015] Due to the favorable mass distribution of the voice coil arrangement the oscillation frequency is shifted towards higher values.

[0016] - The proposed design allows passive and active reduction of sway.

[0017] Typically, the outer magnetic circuit area can include:

[0018] - an extension of the base plate in the deflection direction, which extension forms a pot together with the base plate, or

[0019] - a side plate adjacent to the bottom plate, which side plate forms a magnetic steel together with the bottom plate, or

[0020] - an outer magnet adjacent to the bottom plate and an outer top plate adjacent to the outer magnet.

[0021] The use of external magnets can increase the magnetic field strength in the magnetic gap. In particular, when a very flat magnetic circuit system is required, this structure can help to obtain the necessary magnetic flux.

[0022] In general, the magnetic gap centerline can be defined as being broken in the region where the diameter of the associated virtual circle exceeds twice the diameter of the smallest virtual circle in the magnetic gap. Thus, this definition can help calculate the above ratios for electro-acoustic transducers (where, for example, there is a large gap in the magnetic circuit system).

[0023] Furthermore, the problem of the invention is solved by an electroacoustic system comprising an electrodynamic acoustic transducer of the above-mentioned kind and a control circuit connected to the voice coil device, the control circuit being designed:

[0024] - determining the position-dependent velocity or the back-EMF of at least two voice coils, in particular all voice coils, of the voice coil arrangement,

[0025] - detect differences in velocity or back EMF associated with the determined position, and

[0026] - generating an output signal which is fed to at least two voice coils (or all voice coils) and cancels out the difference.

[0027] In this way, oscillations are actively avoided or at least reduced. It is particularly advantageous that control movement and sound output can be performed simultaneously.

[0028] In particular, the output signal can be fed to an amplifier or driver of the voice coil and superimposed on the audio signals, which are converted into audible sounds by the electroacoustic transducer. By the above measures, the oscillation can be avoided or at least actively reduced. The oscillating movement of the voice coil arrangement is detected by the difference in position-dependent velocity or back electromotive force, and an output signal is in turn fed to the voice coil, which output signal counteracts the oscillation. Therefore, the above electroacoustic system comprises a oscillation control loop.

[0029] It should be noted that deviations from the given numbers defined in the patent claims, which are unavoidable in reality due to technical tolerances, are generally covered by these patent claims anyway. Specifically, this means that the numbers defined in the patent claims are considered to include a range of + / -10% about the base value.

[0030] Typically, the "frame" is the part that holds the diaphragm, the voice coil arrangement and the magnetic circuit system together. Typically, the frame is directly connected to the diaphragm and the magnetic circuit system (for example, with the help of an adhesive), while the voice coil is connected to the diaphragm. The frame is thus fixedly arranged with respect to the magnetic circuit system. Typically, the frame together with the diaphragm, the voice coil arrangement and the magnetic circuit system forms a subsystem that is the result of an intermediate step in the production process.

[0031] A "housing" is usually mounted to the frame and / or the diaphragm and surrounds the back volume of the transducer, i.e. the air compartment or gas compartment behind the diaphragm. The housing is thus arranged fixedly with respect to the magnetic circuit system. In a typical design, the housing can be hermetically sealed. However, as the case may be, it can also include small openings or bass tubes. In particular, the acoustic properties of the transducer can be influenced by changing the back volume by providing openings in the housing.

[0032] The proposed design is generally applicable to loudspeakers, especially for loudspeakers with a diaphragm area less than 600mm. 2 and / or the back cavity volume is 200mm 3 Up to 2cm 3 Miniature speakers in the range of 100 to 200 ft are used in all kinds of mobile devices, such as mobile phones, mobile music devices, laptop computers and / or headphones. It should be noted at this point that a miniature speaker does not necessarily include its own back volume, but can use the space of the device in which the speaker is built as the back volume. This means that the speaker does not include its own (closed) housing, but only an (open) frame. The back volume of a device with such a speaker built in is usually less than 10 cm 3 .

[0033] Further details and advantages of audio transducers of the disclosed kind will become apparent from the following description and accompanying drawings.

[0034] Advantageously, the central magnets are arranged in a matrix pattern, when viewed in a direction parallel to the offset direction, wherein adjacent central magnets have different magnetic orientations. In this way, the proposed measures can be applied to electro-acoustic transducers with a rectangular footprint. A matrix in a given context may refer to a matrix in which all fields are captured by the magnets as well as a matrix in which fields are only partially captured by the magnets. For example, only 7 fields of a 9×9 sparse matrix may be captured by the magnets.

[0035] Alternatively, the central magnets can each be shaped as a circular segment when viewed in a direction parallel to the deflection direction. In this way, the proposed measures can be applied to electro-acoustic transducers having a circular footprint.

[0036] Advantageously, the area of ​​the / all central magnets is the same when viewed in a direction parallel to the deflection direction. In this way, a high degree of symmetry can be achieved which is beneficial for anti-wobble.

[0037] It is particularly advantageous if the center magnets are arranged with respect to their magnetic orientation point-symmetrically about a transducer axis parallel to and arranged at the center of the voice coil axis, or rotationally symmetrically about a transducer axis parallel to and arranged at the center of the voice coil axis according to a rotation angle of ≤180°. In this way, as large a share as possible of the magnetic gap E is exposed to a large amount of magnetic flux. The reason for this is that the above conditions ensure a maximum of oppositely magnetized center magnets (i.e., a maximum opposite magnetic orientation) and therefore a maximum magnetic gap area arranged between these oppositely magnetized center magnets. In other words, the above conditions ensure that as large a part as possible of the center line of the magnetic gap extends through the oppositely magnetized center magnets.

[0038] In the following, some embodiments of an electrodynamic acoustic transducer are presented, which generally improve the symmetry of the electrodynamic acoustic transducer and thus provide passive swing protection:

[0039] The central magnets can be arranged with respect to their shape with point symmetry around the transducer axis or with rotation symmetry with respect to a rotation angle of ≤180° around the transducer axis.

[0040] The magnetic flux generated by the central magnet can be distributed point-symmetrically around the transducer axis, or rotationally symmetrically around the transducer axis at a rotation angle of ≤180°.

[0041] - The force factor associated with the magnetic circuit system and the voice coil arrangement can be distributed point-symmetrically around the transducer axis, or rotationally symmetrically around the transducer axis for a rotation angle of ≤180°. In general, the force factor BL(x) is a metric that allows the force on the voice coil in a magnetic field to be calculated by multiplying the force factor BL(x) with the current through the voice coil.

[0042] The mass of the voice coil arrangement may be distributed point-symmetrically around the transducer axis, or rotationally symmetrically around the transducer axis at a rotation angle of ≤ 180°.

[0043] The centre of gravity of the voice coil may be distributed point-symmetrically around the transducer axis, or rotationally symmetrically around the transducer axis at a rotation angle of ≤180°.

[0044] - The magnetic circuit system may comprise an even number of central magnets.

[0045] The area of ​​the central magnet and the length of the electrical conductors in the annular section of the voice coil seen in a direction parallel to the transducer axis may be distributed point-symmetrically around the transducer axis or rotationally symmetrically around the transducer axis at a rotation angle of ≤180°.

[0046] The last embodiment focuses on the area of ​​the center magnet and the length of the electrical conductor in the annular section of the voice coil, and has little to do with the symmetry of the shape of the center magnet. This means that the above conditions can also be met by differently shaped center magnets and voice coils. However, the contribution of the various magnet-voice coil pairs is essentially the same, because the area of ​​the center magnet (and the flux it produces) and the length of the voice coil (and the force it produces) are the same. For example, a corner of the center magnet can be cut for the connection of the associated voice coil, while the other center magnets do not have such a cut, or at the same position but at a different position. It is advantageous if the asymmetry is formed at the corners of the center magnet (if necessary), because the magnetic field there is not too strong, and therefore the effect of this asymmetry is not too strong. Nevertheless, the asymmetry can be formed on the longitudinal sides of the center magnet.

[0047] In a further advantageous embodiment of the electrodynamic acoustic transducer, the magnetic circuit system has an overall width, an overall length and an overall height according to a Cartesian coordinate system, wherein the overall length is the maximum extension of the magnetic circuit system and the overall height is the minimum extension of the magnetic circuit system, and wherein the ratio of the overall length to the overall height is ≥10, and wherein in particular the ratio is in the range of 10 to 100. In this way, the properties of the electrodynamic acoustic transducer with respect to the stiffness similar to that of the rigid diaphragm part, the magnetic permeability and the thermal operating point of the electrodynamic acoustic transducer, the efficiency and sensitivity of the electrodynamic acoustic transducer, the cooling of the electrodynamic acoustic transducer, the reduction of magnetic stray fields, the offset oscillation frequency and the reduction of oscillation are further improved.

[0048] In a further advantageous embodiment of the electrodynamic acoustic transducer, the magnetic circuit system has an area seen in a direction parallel to the transducer axis and a total height measured in a direction parallel to the transducer axis, wherein a ratio of the square root of the area to the total height is ≥ 10, and wherein in particular the ratio is in the range from 10 to 100. This embodiment further improves the above-mentioned characteristics of the electrodynamic acoustic transducer.

[0049] It is particularly advantageous if the voice coil is made of metal foils stacked on top of each other in the direction of the transducer axis with an insulating layer between the metal foils, wherein the electrical conductors of the voice coil have a rectangular cross section in a cross-sectional view and wherein the long sides of the rectangular cross section in the cross-sectional view are arranged perpendicular to the transducer axis. In general, the use of metal foils for voice coils has many advantages:

[0050] - Firstly, the power density within the voice coil increases, since the share of the voice coil volume occupied by the conductive layer is quite high and is especially high for voice coils consisting of wires with a circular cross section. The improved cooling effect mentioned above helps to manage the temperature of the voice coil at such high power densities.

[0051] - Secondly, the use of metal foil improves the mechanical stability of the voice coil compared to voice coils consisting of wires with a circular cross section. Thus, this embodiment of the voice coil further improves the stiffness of the rigid diaphragm part. This is why the rigid diaphragm part can be made even lighter (which provides a further positive influence on the frequency response of the electrodynamic acoustic transducer).

[0052] - Thirdly, the manufacture of foil-based voice coils is easier than the production of wired voice coils. In particular, the effort to manufacture a voice coil arrangement by using metal foil is essentially independent of the number of voice coils of the voice coil arrangement. This is not the case when voice coils are conventionally wound with wire. Here, the effort to manufacture a voice coil arrangement increases linearly with the number of voice coils of the voice coil arrangement.

[0053] A "conductive layer" is a layer of the voice coil that is able to conduct a considerable level of electric current. In the present invention, the conductive layer is made of metal. It should be noted at this point that a "stack of conductive layers" does not exclude the presence of other layers between the conductive layers, especially referring to "insulating layers", "passivation layers" and / or "adhesive layers". In general, for example, metal foils for electrical conductors of voice coils can be made of copper, aluminum and any copper alloy or aluminum alloy. However, the proposed method is generally applicable to conductive foils. Therefore, if a material different from metal but with comparable or better conductivity is provided, in this context, the term "metal foil" can be conceptually replaced by the term "conductive foil".

[0054] An "insulating layer" is a layer of the voice coil that is subject to substantial levels of voltage and is incapable of conducting substantial levels of current. Examples of materials that may be used to construct the insulating layer are plastics, ceramics, and oxides. The insulating layer may include layers of a single insulating material, layers of different insulating materials (such as the materials mentioned previously), or one or more layers comprising a mixture of materials.

[0055] A "passivation layer" is a protective layer on a conductive layer. It can be produced by oxidation of the metal of the conductive layer. Thus, the passivation layer can contain a metal oxide. Usually, the passivation layer has insulating properties. In this case, the passivation layer is part of the insulating layer. The production of the passivation layer is optional, and the insulating layer can also be constructed without a passivation layer.

[0056] An "adhesive layer" is a layer that mechanically connects two adjacent layers by adhesion. The adhesive layer usually also has insulating properties. In this case, the adhesive layer is also part of the insulating layer. Therefore, the insulating layer can usually include a passivation layer and / or an adhesive layer. The adhesive layer can be made of glue, which is applied to the conductive layer or to the passivation layer on the conductive layer, for example by spraying, pad printing or roller coating. Liquid glue can also be applied to the gap between two conductive layers or passivation layers.

[0057] Advantageously, the ratio of the long side of the rectangular cross section to the short side of the rectangular cross section is > 1.5. In this way, a preferred aspect ratio of the voice coil and a desired number of turns can be achieved.

[0058] Advantageously, the thickness of the conductive layer is 5 μm to 60 μm, and / or the total thickness of the insulating layer is 0.5 μm to 5 μm. In this way, a desired number of turns can be provided within a desired height of the voice coil. Furthermore, the electrical strength of the insulating layer is high enough to withstand the voltage difference between the conductive layers, and the mechanical stability is high enough to withstand the forces applied to the voice coil during use, both without significantly reducing the advantageous power-to-weight ratio of the voice coil.

[0059] Advantageously, the proportion of the volume of the voice coil taken up by all the conductive layers is >80%. In this way, the power density within the voice coil arrangement is particularly high.

[0060] Advantageously, the voice coil arrangement of the electroacoustic system may comprise four voice coils, wherein the control circuit is connected to three of the four voice coils and is designed to:

[0061] - detecting the position-dependent velocities or back-EMFs of the three voice coils,

[0062] - detect differences in velocity or back EMF related to the detected position, and

[0063] - generating an output signal which is fed to the three voice coils and cancels out the differences.

[0064] Accordingly, the control circuit has only a few terminals and few components, since only three voice coils are required to realize the full function of the swing protection.

[0065] In the above context, it is advantageous that the control circuit for generating the output signal comprises a bridge circuit having four bridge sections, each bridge section comprising two transistors switched in series and connected to each other at a connection point, wherein the connection point of the common bridge section is connected to the connection point of the three voice coils, and the connection points of the remaining bridge sections are respectively connected to the other ends of the three voice coils. Here, the voice coils are star-connected. Likewise, although only three of the four voice coils are used for active swing control, the full functionality of the swing protection can still be provided.

[0066] Advantageously, the voice coil arrangement may comprise four voice coils, two of the four voice coils being electrically switched in parallel or in series and forming a grouped voice coil, wherein the remaining voice coil forms a single voice coil, and wherein the control circuit is connected to the two single voice coils and the grouped voice coil and is designed to:

[0067] - detecting the position-dependent velocity or back-EMF of the single voice coil and the grouped voice coils,

[0068] - detect differences in velocity or back EMF related to the detected position, and

[0069] - generating an output signal which is fed to the single voice coil and the grouped voice coil and cancels out the differences.

[0070] In this embodiment, all four of the four voice coils are used for panning control, but the control circuit still requires only a few terminals and has only a few components.

[0071] In the above context, the following situation is advantageous: the control circuit for generating the output signal comprises a bridge circuit having four bridge sections, each bridge section comprising two transistors switched in series and connected to each other at a connection point, wherein the connection point of a common bridge section is connected to the connection point of the grouped voice coil and the two single voice coils, and the connection points of the remaining bridge sections are respectively connected to the other ends of the grouped voice coil and the two single voice coils. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] These and other aspects, features, details, utilities and advantages of the present invention will become more apparent from the following detailed description, the appended claims and the accompanying drawings, which illustrate features according to exemplary embodiments of the present invention, and wherein:

[0073] Figure 1 shows a cross-sectional side view of an exemplary electrodynamic acoustic transducer;

[0074] Figure 2 shows a perspective view of a driver for an electrodynamic acoustic transducer;

[0075] Figure 3 Shows Figure 2An exploded view of the drive;

[0076] Figure 4 Shows Figure 2 A schematic top view of a drive;

[0077] Figure 5 shows a perspective view of an alternative driver for an electrodynamic acoustic transducer having a side magnet;

[0078] Figure 6 shows a perspective view of an alternative driver for an electrodynamic acoustic transducer having a triangular shaped central magnet;

[0079] Figure 7 Passive sway prevention by passing lateral airflow through an electro-acoustic transducer is shown;

[0080] Figure 8 shows a schematic diagram of an exemplary electroacoustic system;

[0081] Fig. 9 Shows Figure 8 A cross-sectional view of a device in which two voice coils are electrically switched in series and form a grouped voice coil;

[0082] Fig.10 Shows Figure 8 A cross-sectional view of a voice coil in which two voice coils are electrically switched in parallel and form a grouped voice coil;

[0083] Fig.11 shows a cross-section through a voice coil made of metal foil;

[0084] Fig.12 shows a schematic top view of central magnets arranged in a 3×2 matrix;

[0085] Fig.13 shows a schematic top view of central magnets arranged in a 3×3 matrix;

[0086] Fig.14 A schematic top view showing 7 central magnets arranged in a 3×3 sparse matrix; and

[0087] Fig.15 A schematic top view of a central magnet in the shape of a circle segment is shown.

[0088] Like reference numerals designate like or equivalent parts throughout the several views. DETAILED DESCRIPTION

[0089] Various embodiments are described herein for various devices. Many specific details are set forth to provide a thorough understanding of the overall structure, function, manufacture, and use of the embodiments described in the specification and illustrated in the drawings. However, it will be appreciated by those skilled in the art that the embodiments may be practiced without such specific details. In other cases, well-known operations, components, and elements are not described in detail to avoid making the embodiments described in the specification unclear. It will be appreciated by those of ordinary skill in the art that the embodiments described and illustrated herein are non-limiting examples, and it will therefore be appreciated that the specific structural and functional details disclosed herein may be representative and do not necessarily limit the scope of the embodiments, which are limited only by the appended claims.

[0090] References throughout the specification to "various embodiments," "some embodiments," "one embodiment," or "an embodiment," etc., mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in at least one embodiment. Therefore, phrases "in various embodiments," "in some embodiments," "in one embodiment," or "in an embodiment," etc., appearing in various places throughout the specification do not necessarily all refer to the same embodiment. In addition, in one or more embodiments, particular features, structures, or characteristics may be combined in any suitable manner. Therefore, particular features, structures, or characteristics illustrated or described in conjunction with one embodiment may be combined in whole or in part with features, structures, or characteristics of one or more other embodiments without limitation, as long as such combination is not illogical or non-functional.

[0091] It must be noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless expressly stated otherwise.

[0092] The terms "first", "second", etc. (if any) in the specification and claims are used to distinguish between similar elements and are not necessarily used to describe a particular order or chronological order. It should be understood that the terms used in this way are interchangeable where appropriate, so that the embodiments of the invention described herein can, for example, operate in a sequence different from that illustrated or otherwise described herein. In addition, the terms "including", "having", and any variations thereof are intended to cover non-exclusive inclusions, so that a process, method, article, or device that includes a series of elements is not necessarily limited to these elements, but may include other elements that are not explicitly listed or inherent to the process, method, article, or device.

[0093] All directional references (e.g., "plus," "minus," "up," "down," "upward," "downward," "left," "right," "leftward," "rightward," "front," "rear," "top," "bottom," "above," "below," "above," "below," "vertical," "horizontal," "clockwise," and "counterclockwise") are used for identification purposes only to aid the reader in understanding the present disclosure and are not intended to be limiting, especially as to position, orientation, or use of any aspect of the present disclosure. It should be understood that the terms so used are interchangeable where appropriate such that the embodiments of the invention described herein are, for example, capable of operation in other orientations than those illustrated or otherwise described herein.

[0094] As used herein, the phrases "configured to," "configured for," and similar phrases indicate that the subject apparatus, device, or system is designed and / or constructed (e.g., through appropriate hardware, software, and / or components) to achieve one or more specific intended purposes, rather than that the subject apparatus, device, or system is capable of performing only those intended purposes.

[0095] Joiner references (e.g., "attached," "coupled," "connected," etc.) are to be interpreted broadly and may include intermediate members between the connection of elements and relative movement between elements. Thus, joiner references do not necessarily infer that two elements are directly connected and in a fixed relationship to each other. It is intended that all matter contained in the above description or shown in the accompanying drawings be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the invention as defined in the appended claims.

[0096] All numbers expressing measurement and the like used in the description and claims are to be understood in any case as being modified by the term “about” or “substantially”, which especially means a deviation of ±10% from the reference value.

[0097] Figures 1 to 4 A first example of a basic structure of the electrodynamic acoustic transducer 1 is shown. Figure 1 shows a cross-sectional side view of an electrodynamic acoustic transducer 1, Figure 2 shows a perspective view of an alternative driver for an electrodynamic acoustic transducer 1 , Figure 3 shows an exploded view of the drive, and Figure 4 A schematic top view of the drive is shown.

[0098] Specifically, the electrodynamic acoustic transducer 1 comprises a frame or housing 2 and a diaphragm 3 fixed to the frame or housing 2, the diaphragm 3 comprising a flexible diaphragm portion 4 and a rigid diaphragm portion 5. The rigid diaphragm portion 5 may be composed of or include a rigid plate that does not significantly change its shape when the electrodynamic acoustic transducer 1 is deflected, while the flexible diaphragm portion 4 may be composed of or include a softer material that significantly changes its shape when the electrodynamic acoustic transducer 1 is deflected.

[0099] In addition, the electro-acoustic transducer 1 includes a magnetic circuit system 6, which includes: a plurality of central magnets 7a..7d, the plurality of central magnets 7a..7d having different magnetic orientations M1..M4; a central top plate 8a..8d, which is arranged adjacent to one of the central magnets 7a..7d (i.e., on top of the central magnets 7a..7d); and a common bottom plate 12, which is arranged adjacent to the central magnets 7a..7d and opposite to the central top plates 8a..8d (i.e., below the central magnets 7a..7d). In addition, the magnetic circuit system 6 includes an outer magnetic circuit region, which surrounds the central magnets 7a..7d and the central top plates 8a..8d, wherein a magnetic gap E is formed between the central top plates 8a..8d and between the central top plates 8a..8d and the outer magnetic circuit region.

[0100] Generally, the outer magnetic circuit region can be implemented in different ways. For example, the outer magnetic circuit region can be composed of or include a side plate 13 adjacent to the bottom plate 12, and the side plate 13 and the bottom plate 12 together form the magnetic steel 9, such as Figure 2 and Figure 3 Here, the magnetic steel 9 is composed of many separate parts. Alternatively, the outer magnetic circuit region can be composed of or include an extension of the bottom plate 12 in the offset direction z, which together with the bottom plate 12 forms the magnetic steel 9, as shown in FIG. Figure 1 As shown. Figure 1 The middle magnetic steel 9 is an integral piece, so the bottom plate 12 is more of a bottom area than a separate part.

[0101] Furthermore, the electrodynamic acoustic transducer 1 comprises a voice coil arrangement 10 having a plurality of voice coils 11a..11d attached to the diaphragm 3 and arranged to be movable relative to the magnetic circuit system 6 in an offset direction z parallel to the transducer axis D. z and with the transducer axis D x and D y Each of the voice coils 11a..11d comprises an annular-shaped electrical conductor 16 (see, for example, Fig.11), the electric conductors 16 extending in the annular section L around the individual voice coil axes C1..C4, wherein the magnetic circuit system 6 is designed to generate a magnetic field BM of the conductors 16 transverse to the voice coils 11a..11d in the annular section L. The voice coil axes C1..C4 are oriented parallel to the deflection direction z, and each of the voice coils 11a..11d surrounds the top plate 8a..8d of the magnetic circuit system 6.

[0102] Figure 2 Different magnetic orientations M1 .. M4 are indicated. Specifically, the center magnets 7a, 7c have magnetic orientations M1, M3 pointing upwards, and the center magnets 7b, 7d have magnetic orientations M2, M4 pointing downwards. In addition to the arrows, Figure 2 , Figure 5 , Figure 6 and Figures 12 to 15 The hatching indicates different magnetic orientations M1 .. M4 and should not be confused with the cut areas in the cross-sectional views.

[0103] The central magnet 7a..7d has a magnet length l1, a magnet width w1 and a magnet height h1. The magnetic circuit system 6 has a total magnetic circuit system length l2, a total magnetic circuit system width w2 and a total magnetic circuit system height h2. The central top plate 8a..8d has a height h3 and the magnetic gap has a magnetic gap width w3.

[0104] Usually, the ratio Below 1, where

[0105] -w g represents the average width of all magnetic gaps E in the magnetic circuit system 6, which is the average value of the diameters d1..d3 of virtual circles K1..K3 inscribed in the magnetic gaps E between the central top plates 8a..8d and the magnetic gaps E between the central top plates 8a..8d and the outer magnetic circuit area, wherein the axes of the virtual circles K1..K3 are parallel to the offset direction z, wherein,

[0106] -A g represents the sum of all magnetic gap areas in the magnetic circuit system 6, the magnetic gap area being the average height h of the central top plates 8a..8d measured in a direction parallel to the deflection direction z. tp Multiply by the magnetic gap length l g , magnetic gap length l g is the total length of the magnetic gap centerline N connecting the centers of the virtual circles K1..K3, where

[0107] -h m represents the average height of the central magnets 7a..7d measured in a direction parallel to the offset direction z, and wherein,

[0108] -A mdenotes the total area of ​​the central magnets 7a..7d when viewed in a direction parallel to the deflection direction z.

[0109] basically, Figure 3 and Figure 4 provides good insights into how the parameters are calculated (note that Figure 4 is a schematic diagram, and the voice coils 11a..11d are drawn here with dotted lines). Figure 4 Three examples of virtual circles K1..K3 inscribed in the magnetic gap E between the central top plates 8a..8d and the magnetic gap E between the central top plates 8a..8d and the outer magnetic circuit area are shown. As can be seen, the diameters d1..d3 of the virtual circles K1..K3 vary, so the width w3 of the magnetic gap E also varies. Parameter w g Simply put, it represents the average value of the diameters d1..d3 or the average value of the width w3 of the virtual circles K1..K3.

[0110] from Figure 4 It can be seen that the centers of the virtual circles K1..K3 form the magnetic gap center line N. g is the average height h of the central top plates 8a..8d tp Multiply by the total length of the magnetic gap centerline N. In this example, the average height h tp It is just the height h3 of the central top plate 8a..8d, but it can be different if said height h3 varies.

[0111] Parameter h m is the average height of the central magnets 7a..7d, in this example it is directly the height hi, but it may also be different if said height hi varies.

[0112] Finally, A m is the total area of ​​the central magnets 7a..7d, which in this example is approximately:

[0113] A m =4·l1·w1

[0114] Through the above measures, many advantages are obtained. In detail:

[0115] - The voice coil arrangement 10 forms a kind of rib on the back side of the rigid diaphragm part 5 and in particular in its middle region. This is why the rigid diaphragm part 5 does not deform so much when the electrodynamic acoustic transducer 1 is deflected. The voice coils 11a..11d therefore serve a dual function. Firstly, they are part of the driver for the electrodynamic acoustic transducer 1 and secondly, they reinforce the rigid diaphragm part 5 essentially at no cost, since the voice coils 11a..11d are required for the drive anyway. On the other hand, this does also mean that the rigid diaphragm part 5 can be made lighter, which has a positive effect on the frequency response of the electrodynamic acoustic transducer 1. This effect occurs in particular when the rib formed by the voice coil arrangement 10 extends along a long extension of the rigid diaphragm part 5, since the ribs are much lighter than if they were extended around the long axis D. x , the rigid diaphragm part 5 is around the short axis D y More susceptible to bending.

[0116] Furthermore, the magnetic permeability and the thermal operating point of the electrodynamic acoustic transducer 1 are improved, thereby improving the overall acoustic performance of the electrodynamic acoustic transducer 1 , especially in terms of the efficiency and sensitivity of the electrodynamic acoustic transducer 1 .

[0117] Furthermore, the cooling of the electrodynamic acoustic transducer 1 is improved, since the surface of the voice coil arrangement 10 is significantly increased compared to a standard configuration. As a result, a higher output power can be obtained for a small electrodynamic acoustic transducer 1 .

[0118] Furthermore, the magnetic stray fields are reduced compared to designs with only one central magnet 7a..7d.

[0119] Furthermore, due to the favorable mass distribution of the voice coil arrangement 10 , the swing frequency is shifted towards higher values.

[0120] Additionally, the proposed design allows passive and active reduction of sway (see Figures 7 to 10 and associated descriptions).

[0121] The above advantages are more prominent if the ratio of the total length l2 of the magnetic circuit system 6 to the total height h2 of the magnetic circuit system 6 is ≥ 10, wherein the total length l2 is the maximum extension of the magnetic circuit system 6 and the total height h2 is the minimum extension of the magnetic circuit system. Specifically, the ratio can be in the range of 10 to 100.

[0122] If the z The above advantages are more prominent if the ratio of the square root of the area of ​​the magnetic circuit system 6 seen in the direction of the magnetic circuit system 6 to the total height h2 of the magnetic circuit system 6 is ≥ 10. Specifically, the area of ​​the magnetic circuit system 6 in this example can be calculated by l2·w2. Specifically, again, the ratio can be in the range of 10 to 100.

[0123] It should be noted that the magnetic gap center line N is not necessarily a continuous line, but can be defined as being broken in a region where the diameter d3 of the associated virtual circle K3 exceeds twice the diameter d1 of the smallest virtual circle K1 in the magnetic gap E. This situation exists when Figure 4 In FIG. 1 , the size of the virtual circle K3 is more than twice the size of the virtual circle K1. Therefore, a gap P of the magnetic gap center line N exists in the corner region.

[0124] exist Figures 1 to 4 In the example shown, the central magnets 7a..7d are arranged in a matrix pattern when viewed in a direction parallel to the deflection direction z, wherein adjacent central magnets 7a..7d have different magnetic orientations M1..M4.

[0125] A matrix in the given context may particularly refer to a matrix in which all fields are captured by the central magnets 7a..7d, Figures 1 to 4 This is the case with the example. Fig.12 and Fig.13 Another example of this arrangement is shown. In detail, Fig.12 A 3×2 matrix of central magnets 7 is shown, and Fig.13 A 3×3 matrix of central magnets 7 is shown. However, the matrix in the given context may also mean a matrix in which all fields are captured by the central magnets 7a..7d, like Figure 1 and Figure 2 However, the matrix in the given context may also represent a sparse matrix where the field is only partially captured by the central magnet 7. For example, Fig.14 An example of a 3×3 sparse matrix is ​​shown in which only 7 fields can be captured by the central magnet 7. It should also be noted in this context that, although it is advantageous for the magnetic circuit system 6 to include an even number of central magnets 7, the magnetic circuit system 6 may also have an odd number of central magnets 7. Fig.14 This is the case with the example.

[0126] In another embodiment, the central magnets 7 ′ can each be shaped as a circular segment when viewed in a direction parallel to the deflection direction z. Fig.15 Here, four central magnets 7 ′ are depicted, but other numbers of central magnets 7 ′ are also possible.

[0127] Please note, Figures 12 to 15 Only the central magnet 7 is shown, but Figure 1 As shown, a complete electro-acoustic transducer 1 of course requires further elements.

[0128] Figure 5 Now another embodiment of a driver for an electrodynamic acoustic transducer 1 is shown, which is similar to Figure 2In contrast, the outer magnetic circuit region consists of or includes outer magnets 14a..14d adjacent to the bottom plate 12 and outer top plates 15a..15d adjacent to the outer magnets 14a..14d. The outer magnets 14a..14d are magnetized opposite to the adjacent central magnets 7a..7d.

[0129] Figure 6 Another embodiment of a driver for an electrodynamic acoustic transducer 1 is shown, which is similar to Figure 5 Again, there are four central magnets 7a..7d, but they are not square shaped but triangular.

[0130] Advantageously, the areas of all central magnets 7a..7d, 7, 7' may be the same when viewed in a direction parallel to the deflection direction z, as is the case in the example shown in the drawings. However, this is not a requirement and the central magnets 7a..7d, 7, 7' may also have different areas.

[0131] Another feature to be noted is that the central magnets 7a..7d with respect to their magnetic orientations M1..M4 can advantageously be arranged about a transducer axis D parallel to and arranged at the center of the voice coil axes C1..C4. z point symmetry, or about a transducer axis D parallel to and arranged at the center of the voice coil axes C1..C4 z According to the rotational symmetry about the rotation angle α ≤ 180°.

[0132] In this way, as large a share as possible of the magnetic gap E is exposed to a large amount of magnetic flux. The reason for this is that the above conditions ensure a maximum of reversely magnetized central magnets 7a..7d (i.e., a maximum reverse magnetic orientation M1..M4) and therefore a maximum magnetic gap area arranged between these reversely magnetized central magnets 7a..7d. In other words, the above conditions ensure that as large a part as possible of the magnetic gap center line N extends through the oppositely magnetized central magnets 7a..7d.

[0133] Further aspects of the symmetry which further demonstrate the above advantages are disclosed below, wherein, in general, the improved degree of symmetry reduces the tendency to wobble in particular.

[0134] For example, the central magnets 7a..7d may be arranged with respect to their shape to be arranged around the transducer axis D z Point symmetry, or around the transducer axis D z Rotational symmetry for rotation angles ≤ 180°. Figures 1 to 6 , Fig.13 and Fig.15 This is the case with the embodiment shown.

[0135] Furthermore, the magnetic flux generated by the central magnets 7a..7d can be distributed around the transducer axis D z Point symmetry, or around the transducer axis D z Rotational symmetry for rotation angles ≤ 180°.

[0136] In addition, the force factor BL(x) associated with the magnetic circuit system 6 and the voice coil device 10 can be distributed around the transducer axis D z Point symmetry, or around the transducer axis D z Rotational symmetry for rotation angles ≤ 180°. In general, the force factor BL(x) is a measure that allows calculating the force on the voice coil in a magnetic field by multiplying the force factor BL(x) with the current through the voice coil.

[0137] Furthermore, the mass of the voice coil device 10 may be distributed around the transducer axis D z Point symmetry, or around the transducer axis D z Rotational symmetry for rotation angles ≤ 180°.

[0138] In addition, the center of gravity of the voice coils 11a..11d may be distributed around the transducer axis D z Point symmetry, or around the transducer axis D z Rotational symmetry for rotation angles ≤ 180°.

[0139] In addition, parallel to the transducer axis D z The area of ​​the central magnet 7a..7d and the length of the electrical conductor 16 in the annular section L of the voice coil 11a..11d can be distributed around the transducer axis D as seen in the direction of z Point symmetry, or around the transducer axis D z Rotational symmetry for rotation angles ≤ 180°.

[0140] Furthermore, the area of ​​the central magnets 7a..7d in a direction parallel to the transducer axis Dz and the length of the electrical conductor 16 in the annular section L of the voice coils 11a..11d may be distributed around the transducer axis Dz. z Point symmetry or rotational symmetry around the transducer axis Dz according to a rotation angle α≤180°. This embodiment focuses on the area A of the central magnet 7a..7d. mand the length of the electrical conductor 16 in the annular section L of the voice coil 11a..11d, and therefore has little to do with the symmetry of the shape of the center magnet 7a..7d. This means that the above conditions can also be met by differently shaped center magnets 7a..7d and voice coils 11a..11d. For example, a corner of the center magnet 7a..7d can be cut for the connection of the associated voice coil 11a..11d, while the other center magnets 7a..7d have no such cutout, or have no such cutout at the same position but at a different position. If an asymmetry is formed at the corners of the center magnet 7a..7d (if necessary), this is advantageous, because the magnetic field BM there is not too strong, and therefore the influence of this asymmetry is also not too strong. Nevertheless, an asymmetry can be formed on the longitudinal sides of the center magnet 7a..7d.

[0141] Now, Figure 7 An effect is shown, which occurs in the proposed electrodynamic acoustic transducer 1 and advantageously avoids or at least reduces the vibration of the diaphragm 3. In detail, Figure 7 The effect of oscillation on the air inside the electroacoustic transducer 1 is shown. Basically, the air moves from the compressed area to the expanded area, such as Figure 7 The voice coils 11a..11d hinder the direct airflow F' from one side of the electrodynamic acoustic transducer 1 to the other side, and the air must instead take a detour and pass through the magnetic gap E. As a result, the flow resistance of the airflow F is much higher than the (impossible) airflow F' that would occur if there were no voice coils 11a..11d in the way. Therefore, the proposed electrodynamic acoustic transducer 1 effectively avoids or at least reduces the oscillation.

[0142] Figure 7 It is shown how the swinging can be avoided or limited passively. However, the swinging can also be avoided or limited actively. Figure 8 In this context a schematic diagram of an electroacoustic system 19 is shown, which comprises an electrodynamic acoustic transducer 1 of the kind disclosed above and a control circuit CC connected to a voice coil arrangement 10. In this embodiment, the control circuit CC comprises a bridge circuit BC, which is connected to a supply voltage VDD and comprises four bridge sections B1..B3, B n . Each bridge part B1..B3, B n With two transistors T1..T switched in series and connected to each other at a connection point n '. Public bridging part B n The connection points of the bridge portions B1 to B3 are connected to the connection points of three voice coils among the plurality of voice coils 11a to 11d, specifically to the voice coils 11a to 11c in this example. The connection points of the remaining bridge portions B1 to B3 are each connected to the other ends of the three voice coils 11a to 11c.

[0143] Furthermore, the electroacoustic system 19 comprises a control unit CU for determining the back electromotive force of the three voice coils 11a..11c and transistors T1..T2 for receiving a control signal and a sound signal S from the control unit CU and driving a bridge circuit BC. n ' driver control unit DCU. In order to determine the back electromotive force, the voltages V1..V3, V n and the currents I1..I2, I through the voice coils 11a, 11b and through the connection points of the voice coils 11a..11c. n The current I3 through the voice coil 11c is not measured directly in this example, but with the aid of the formula I3=I n However, it is easy for a person skilled in the art to understand that other ways to obtain the expected value are also possible.

[0144] Based on this data, the back EMF V emf1 ..V emf3 It can be determined or calculated as follows:

[0145] V emf1 (t)=V1(t)-V n (t)-Z C1 I1(t)

[0146] V emf2 (t) = V2(t) - V n (t)-Z C2 I2(t)

[0147] V emf3 (t)=V3(t)-V n (t)-Z C3 I3(t)

[0148] Among them, Z C1 , Z C2 and Z C3 is the voice coil impedance of the voice coils 11a..11c.

[0149] As shown in the formula, the back electromotive force V emf1 ..V emf3 , voltage V1..V3, V n and currents I1..I3, I n It should also be noted that the voice coil impedance Z C1 ..Z C3The real part of is not necessarily constant over time, but may change, for example, depending on the voice coil temperature. To measure the voice coil resistance, a (inaudible) tone or a sinusoidal signal may be applied to the voice coils 11a..11c. In the case of a microspeaker, such a tone or sinusoidal signal may in particular have a frequency below 100 Hz, for example 50 Hz. It should be noted that the voice coil impedance Z C1 ..Z C3 changes slowly over time. That is why considering the voltages V1..V3, V n and currents I1..I3, I n The rapid change of the voice coil impedance Z C1 ..Z C3 However, strictly speaking, the voice coil impedance Z C1 ..Z C3 You can also use "Z C1 (t)..Z C3 (t)”.

[0150] In addition, it should be noted that Z C1 ..Z C3 is a complex number in the above formula. However, to simplify the calculation, the (real-valued and instantaneous) voice coil resistance R C1 ..R C3 Instead of complex value Z C1 ..Z C3 , thus ignoring the voice coil resistance R C1 ..R C3 Therefore, in this disclosure, “Z C1 ..Z C3 " can be changed to "R C1 ..R C3 "For the electromotive force V emf1 ..V emf3 The formula means:

[0151] V emf1 (t)=V1(t)-V n (t)-R C1 I1(t)

[0152] V emf2 (t) = V2(t) - V n (t)-R C2 I2(t)

[0153] V emf3 (t)=V3(t)-V n (t)-R C2 I2(t)

[0154] The control circuit CC is designed as follows:

[0155] - Determine the back EMF V of the three voice coils 11a..11c emfl ..V emf3 ,

[0156] - Detect back electromotive force V emf1 ..V emf3 The difference, and

[0157] - Generate an output signal which is fed to the three voice coils 11a..11c and cancels out the differences.

[0158] Specifically, a control signal is generated in the control unit CU and fed to the driver control unit DCU, wherein the control signal is superimposed on an audio signal or sound signal S from an audio source (not shown), and wherein transistors T1..T n '. The amplified transistor control signals form the output signals of the voice coils 11a..11c. These output signals are converted by the electro-acoustic transducer 1 into audible sounds caused by the sound signal S and control movements caused by the control signals of the control unit CU. In this way, oscillations are actively avoided or at least reduced. It is particularly advantageous that the control movements and the sound output can occur almost instantaneously.

[0159] In an alternative embodiment, the above method may also be based on the position-dependent velocity of the voice coils 11a..11c, which may be calculated as follows:

[0160]

[0161]

[0162]

[0163] or via:

[0164]

[0165]

[0166]

[0167] Wherein, BL1(0) .. BL3(0) represent the force factors of the voice coils 11a .. 11c in their idle positions. Accordingly, the control circuit CC can also be designed as:

[0168] - determine the position-dependent velocities v1..v3 of the three voice coils 11a..11c,

[0169] - detect differences in position-dependent velocities v1..v3, and

[0170] - Generate an output signal which is fed to the three voice coils 11a..11c and cancels out the differences.

[0171] exist Figure 8 In the context of the illustrated implementation, the following points should be kept in mind:

[0172] -exist Figure 8 In the embodiment of the present invention, two voice coils of the three voice coils 11a..11c are used for swing detection. In detail, the back electromotive force V from the voice coils 11a and 11b is emf1 、V emf2 For around axis D y The back electromotive force V from the voice coils 11b and 11c is emf2 、V emf3 For around axis D x Swing detection (see also in this context, for example Figure 2 ). Note that equivalently, the position-dependent velocities v1..v3 can be used for swing detection.

[0173] - To detect around multiple axes D x , D y The voice coils 11a..11c for swing detection should not be located in a line. Figure 2 In the embodiment of , the voice coils 11a..11c form a corner. However, for reasons of multi-axis wobble detection, alternative arrangements of the voice coils 11a..11c other than a straight arrangement are also possible.

[0174] - The oscillation around the general axis is considered to be around the axis D x The oscillating movement and the rotation around the axis D y In other words, the swing in any direction can be divided into the swing around the axis D x The swing component and the swing component around the axis D y Another component of .

[0175] - Although only three of the plurality of voice coils 11a..11d are used to detect the swing, all four voice coils 11a..11d are driven by the bridge circuit BC, which means that the sound signal S is also fed to the voice coil 11d. However, for simplicity, Figure 8 The voice coil 11d is not shown.

[0176] In order to avoid additional wiring and output stages, more than a given number of voice coils 11a..11d may be divided into three groups, such as Fig. 9 and Fig.10 For example, in the figure, three groups are formed by four voice coils 11a..11d.

[0177] In detail, Fig. 9 Shows Figure 8 An alternative cross-sectional view of the embodiment of the invention, wherein the electrical connection of the voice coils 11a..11d is modified. In detail, the two voice coils 11a, 11b are electrically switched in series and form Fig. 9 The control circuit CC is connected to the two single voice coils SVC and the grouped voice coil GVC, and is designed as follows:

[0178] - Detection of the position-dependent velocities v1..v3 or back-EMF V of the single voice coil SVC and the grouped voice coil GVC emf1 ..V emf3 ,

[0179] - Detection of the detected position-dependent velocity v1..v3 or back-EMF V emf1 ..V emf3 The difference, and

[0180] - generating an output signal which is fed to the single voice coil SVC and the grouped voice coil GVC and cancels out the difference.

[0181] Basic operation mode and Figure 8 The only difference is that the two voice coils 11a, 11b are electrically switched in series and form a grouped voice coil GVC.

[0182] In this embodiment, the back electromotive force V from the grouped voice coil GVC emf1 and V from voice coils 11c and 11d emf2 For around axis D x The swing detection and the back electromotive force V from the voice coils 11c and 11d emf2 、V emf3 For around axis D y Swing detection (see again in this context, for example Figure 2 ). Note again that, equivalently, the position-dependent velocities v1..v3 can be used for swing detection.

[0183] Fig.10 Shows something like Fig. 9 Again, the basic mode of operation is similar to Figure 8 and Fig. 9 The only difference is that two voice coils 11a, 11b are electrically switched in parallel and form a grouped voice coil GVC. Therefore, two voice coils 11a, 11b are electrically switched in parallel and form a grouped voice coil GVC, while the remaining voice coils 11c, 11d form a single voice coil SVC.

[0184] Again, the back EMF V from the grouped voice coil GVC emf1 and V from voice coils 11c and 11d emf2 For around axis D x The swing detection and the back electromotive force V from the voice coils 11c and 11d emf2 、V emf3 For around axis D y Swing detection (see again in this context, for example Figure 2 ). Note again that, equivalently, the position-dependent velocities v1..v3 can be used for swing detection.

[0185] Fig.10 The embodiment of has some advantages. The selected grouping results in a lower impedance, but at the same time generates the same forces in each of the grouped voice coils 11a, 11b, because the same current flows through each of the voice coils 11a, 11b. This is particularly useful if the given supply voltage VDD for all voice coils 11a..11d is the same as seen by the bridge circuit BC. In other words, Fig.10 The embodiment of provides the advantage that the voice coils 11a..11d can be identical and only the bridge circuit BC has to provide the higher current for the two voice coils 11a, 11b which are electrically switched in parallel and form the grouped voice coil GVC.

[0186] The disclosed principle can be applied to basically any number of voice coils 11a..11d or more. In particular, the principle can be applied to all voice coils 11a..11d of the electrodynamic acoustic transducer 1. However, some limitations should still be considered, such as the interface connection with the bridge circuit BC and the quality, impedance Z C1 ..Z C3 and the number of windings of each voice coil 11a..11d.

[0187] Typically, the voice coils 11a..11d may be made of or include a wire wound around the associated voice coil axis C1..C4, but this is not the only possibility. The voice coils 11a..11d may also be made of a metal foil formed on the transducer axis D z The conductive layers G1..G3 are stacked on top of each other in the direction of 12 , H 23 , this is Fig.11 The electric conductor 16 of the voice coil 11a..11d has a rectangular cross section in the cross-sectional view, wherein the long side w4 of the rectangular cross section in the cross-sectional view is arranged perpendicular to the transducer axis D z . Insulation layer H 12 , H 23The invention comprises a passivation layer 17 and an adhesive 18 located between the passivation layers 17 .

[0188] Advantageously, the ratio of the long side w4 of the rectangular cross section of the electrical conductor 16 or the conductive layer G1..G3 to the short side h4 of the rectangular cross section is >1.5. Furthermore, if the thickness h4 of the conductive layer G1..G3 is 5 μm to 60 μm and / or the insulating layer H 12 , H 23 It is advantageous if the total thickness h5 of the voice coil 11 a .. 11 d is 0.5 μm to 5 μm. Finally, it is advantageous if all conductive layers G1 .. G3 account for >80% of the volume of the voice coil 11 a .. 11 d .

[0189] Generally, using metal foil 16 for voice coils 11a..11d has many advantages:

[0190] Firstly, the power density within the voice coil 11a..11d is increased, since the share of the volume of the voice coil 11a..11d occupied by the conductive layers G1..G3 is relatively high, and is especially high for voice coils 11a..11d consisting of wires with a circular cross section. The improved cooling effect mentioned above helps to manage the temperature of the voice coil 11a..11d at such high power densities.

[0191] Secondly, the use of the metal foil 16 improves the mechanical stability of the voice coils 11a..11d compared to voice coils 11a..11d consisting of a wire with a circular cross section. Therefore, this embodiment of the voice coils 11a..11d further improves the stiffness of the rigid diaphragm part 5. This is why the rigid diaphragm part 5 can be made even lighter (which provides a further positive influence on the frequency response of the electrodynamic acoustic transducer 1).

[0192] Third, the manufacture of the foil-based voice coils 11a..11d is easier than the production of wired voice coils 11a..11d. Specifically, the effort to manufacture the voice coil assembly 10 by using metal foil is substantially independent of the number of voice coils 11a..11d per voice coil assembly 10. This is not the case when the voice coils 11a..11d are conventionally wound with wires. Here, the effort to manufacture the voice coil assembly 10 increases linearly with the number of voice coils 11a..11d per voice coil assembly 10.

[0193] It should be noted that the present invention is not limited to the above-described embodiments and exemplary working examples. Additional developments, modifications and combinations are also within the scope of the patent claims and are understood by those skilled in the art from the above disclosure. Therefore, the techniques and structures described and illustrated herein should be understood to be illustrative and exemplary, rather than to limit the scope of the present invention.

[0194] The scope of the present invention is defined by the appended claims, including known equivalents and unforeseeable equivalents at the time of filing this application. Although many embodiments of the present invention have been described above with a certain degree of particularity, those skilled in the art may make various changes to the disclosed embodiments without departing from the spirit or scope of the present disclosure.

[0195] Reference numerals list

[0196] 1 Electrodynamic Acoustic Transducer

[0197] 2 Frame / housing

[0198] 3 Diaphragms

[0199] 4 Flexible diaphragm part

[0200] 5 Rigid diaphragm section

[0201] 6 Magnetic circuit system

[0202] 7a..7d,7,7'Center magnet

[0203] 8a..8d Center top plate

[0204] 9 Magnet

[0205] 10 Voice coil device

[0206] 11a..11d Voice coil

[0207] 12 Bottom Plate

[0208] 13 Side Panel

[0209] 14a..14d External magnet

[0210] 15a..15d External top plate

[0211] 16 Electrical wires

[0212] 17 Passivation layer

[0213] 18 Adhesive

[0214] 19 Electroacoustic System

[0215] α Angle

[0216] d1..d3 diameter

[0217] w3 Magnetic gap width

[0218] h1 Height of magnet

[0219] l1 Magnet length

[0220] w1 Magnet width

[0221] h2 Total magnetic circuit system height

[0222] l2 Total magnetic circuit system length

[0223] w2 Total magnetic circuit system width

[0224] z offset direction

[0225] h3 Height of the center top plate

[0226] w4 Width of the conductive layer (long side)

[0227] h4 Thickness of the conductive layer (short side)

[0228] h5 (total) insulation thickness

[0229] A m Total area of ​​central magnet

[0230] BM Magnetic Field

[0231] C1..C4 Voice coil axis

[0232] D x ..D z Transducer axis

[0233] E Magnetic gap

[0234] F, F' airflow

[0235] G1..G3 Conductive layer

[0236] H 12 , H 23 Insulation layer

[0237] I1..I3、I n Voice coil current

[0238] K1..K3 virtual circle

[0239] L Ring segment

[0240] M1..M4 Magnetic Orientation

[0241] N Magnetic gap centerline

[0242] P Gap of magnetic gap centerline

[0243] S Sound signal

[0244] T1..T n ' transistor

[0245] V1..V3,V n Voice coil voltage

[0246] B1..B3, B n Bridge section

[0247] BC bridge circuit

[0248] CC Control Circuit

[0249] CU Control Unit

[0250] DCU Drive Control Unit

[0251] VDD supply voltage

[0252] SVC Single Voice Coil

[0253] GVC Grouped Voice Coil

Claims

1. An electrodynamic acoustic transducer, the electrodynamic acoustic transducer include: - a frame and / or a housing; - a diaphragm fixed to the frame or the housing; - a magnetic circuit system, the magnetic circuit system comprising: a plurality of central magnets, the plurality of central magnets having different magnetic orientations; central top plates, each of the central top plates being arranged adjacent to one of the central magnets; a common bottom plate, the common bottom plate being arranged adjacent to the central magnet and opposite to the central top plate; and an outer magnetic circuit region, the outer magnetic circuit region surrounding the central magnet and the central top plate, wherein magnetic gaps are formed between the central top plates and between the central top plate and the outer magnetic circuit region, - a voice coil device having a plurality of voice coils attached to the diaphragm and arranged to be movable in an offset direction relative to the magnetic circuit system, wherein each of the plurality of voice coils comprises an annular-shaped electrical conductor extending around a separate voice coil axis in an annular section, wherein the voice coil axis is parallel to the offset direction, wherein the magnetic circuit system is designed to generate a magnetic field transverse to the electrical conductor of the voice coil in the annular section, and wherein each of the plurality of voice coils surrounds a top plate of the magnetic circuit system, It is characterized by the ratio Below 1, where -w g represents the average width of all magnetic gaps in the magnetic circuit system, the average width is the average value of the diameters of virtual circles inscribed in the magnetic gaps between the central top plates and the magnetic gaps between the central top plates and the outer magnetic circuit region, wherein the axis of the virtual circle is parallel to the offset direction, wherein, -A g represents the sum of all magnetic gap areas in the magnetic circuit system, where the magnetic gap area is the average height h of the central top plate measured in a direction parallel to the offset direction. tp Multiply by the magnetic gap length l g , the magnetic gap length l g is the total length of the magnetic gap centerline connecting the centers of the virtual circles, where, -h m represents the average height of the central magnet measured in a direction parallel to the offset direction, and wherein, -A m represents the total area of ​​the central magnet when viewed in a direction parallel to the offset direction.

2. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The outer magnetic circuit region includes: - an extension of the common bottom plate in the offset direction, the extension forming a magnetic steel together with the common bottom plate, or - a side plate, the side plate being adjacent to the common bottom plate, the side plate and the common bottom plate forming a magnetic steel together, or - an outer magnet adjacent to said common bottom plate and an outer top plate adjacent to said outer magnet.

3. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The magnetic gap centerline is broken in an area where the diameter of the associated virtual circle exceeds twice the diameter of the smallest virtual circle in the magnetic gap.

4. The electrodynamic acoustic transducer according to claim 1, It is characterized in that When viewed in a direction parallel to the deflection direction, the central magnets are arranged in a matrix pattern, wherein adjacent central magnets have different magnetic orientations.

5. The electrodynamic acoustic transducer according to claim 1, It is characterized in that When viewed in a direction parallel to the deflection direction, the central magnets are each shaped as a circle segment.

6. The electrodynamic acoustic transducer according to claim 1, It is characterized in that When viewed in a direction parallel to the deflection direction, all central magnets have the same area.

7. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The central magnets are arranged with respect to their magnetic orientations in point symmetry around a transducer axis or in rotation symmetry around the transducer axis at a rotation angle of ≤180°, the transducer axis being parallel to the voice coil axis and arranged at the center of the voice coil axis.

8. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The central magnets are arranged with respect to their shape in a point-symmetrical manner around the transducer axis or in a rotationally symmetrical manner around the transducer axis at a rotation angle of ≤180°.

9. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The magnetic flux generated by the central magnet is distributed point-symmetrically around the transducer axis, or rotationally symmetrically around the transducer axis at a rotation angle of ≤180°.

10. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The force factors associated with the magnetic circuit system and the voice coil device are distributed in a point-symmetric manner around the transducer axis, or in a rotationally symmetric manner around the transducer axis at a rotation angle of ≤180°.

11. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The mass of the voice coil device is distributed point-symmetrically around the transducer axis, or rotationally symmetrically around the transducer axis at a rotation angle of ≤180°.

12. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The center of gravity of the voice coil is distributed to be point-symmetrical about the transducer axis, or to be rotationally symmetrical about the transducer axis at a rotation angle of ≤180°.

13. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The area of ​​the central magnet seen in a direction parallel to the transducer axis and the length of the electric conductor in the annular section of the voice coil are distributed point-symmetrically around the transducer axis or rotationally symmetrically around the transducer axis at a rotation angle of ≤180°.

14. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The magnetic circuit system includes an even number of central magnets.

15. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The magnetic circuit system has an overall width, an overall length and an overall height according to a Cartesian coordinate system, wherein the overall length is the maximum extension of the magnetic circuit system and the overall height is the minimum extension of the magnetic circuit system, and wherein the ratio of the overall length to the overall height is ≥10.

16. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The magnetic circuit system has an area seen in a direction parallel to the transducer axis and a total height measured in a direction parallel to the transducer axis, wherein a ratio of a square root of the area to the total height is ≥10.

17. The electrodynamic acoustic transducer according to claim 1, It is characterized in that The voice coil is made of metal foils which are stacked on top of each other in the direction of the transducer axis with an insulating layer between the metal foils, wherein the electrical conductor of the voice coil has a rectangular cross-section in a cross-sectional view, and wherein the long side of the rectangular cross-section in the cross-sectional view is arranged perpendicular to the transducer axis.

18. The electrodynamic acoustic transducer according to claim 17, It is characterized in that The ratio of the long side of the rectangular cross section to the short side of the rectangular cross section is greater than 1.

5.

19. The electrodynamic acoustic transducer according to claim 17, It is characterized in that The thickness of the conductive layer is 5 μm to 60 μm, and / or the total thickness of the insulating layer is 0.5 μm to 5 μm.

20. The electrodynamic acoustic transducer according to claim 17, It is characterized in that The share of the volume of the voice coil occupied by all conductive layers is >80%.

21. An electroacoustic system, comprising the electroacoustic transducer according to claim 1, It is characterized in that A control circuit is connected to the voice coil device, and the control circuit is designed to: - detecting the position-dependent velocity or the back-EMF of at least two voice coils of the voice coil arrangement, - detect differences in velocity or back EMF related to the detected position, and - generating an output signal which is fed to the at least two voice coils and cancels out the difference.

22. The electroacoustic system according to claim 21, It is characterized in that The voice coil device includes four voice coils, and the control circuit is connected to three of the four voice coils and is designed to: - detecting the position-dependent velocities or back-EMFs of the three voice coils, - detect differences in velocity or back EMF related to the detected position, and - generating an output signal which is fed to the three voice coils and cancels out the differences.

23. The electroacoustic system according to claim 22, It is characterized in that The control circuit for generating the output signal comprises a bridge circuit having four bridge sections, each bridge section comprising two transistors switched in series and connected to each other at a connection point, wherein a connection point of a common bridge section is connected to a connection point of the three voice coils, and connection points of the remaining bridge sections are respectively connected to the other ends of the three voice coils.

24. The electroacoustic system according to claim 21, It is characterized in that The voice coil device comprises four voice coils, two of the four voice coils are electrically switched in parallel or in series and form a grouped voice coil, wherein the remaining voice coils form two single voice coils, and wherein the control circuit is connected to the two single voice coils and the grouped voice coils and is designed to: - detecting the position-dependent velocity or back-EMF of the two single voice coils and the grouped voice coils, - detect differences in velocity or back EMF related to the detected position, and - generating an output signal which is fed to the two single voice coils and the grouped voice coil and cancels out the difference.

25. The electroacoustic system according to claim 24, It is characterized in that The control circuit for generating the output signal comprises a bridge circuit having four bridge sections, each bridge section comprising two transistors switched in series and connected to each other at a connection point, wherein a connection point of a common bridge section is connected to a connection point of the grouped voice coil and the two single voice coils, and connection points of the remaining bridge sections are respectively connected to the other ends of the grouped voice coil and the two single voice coils.

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