ELECTRODYNAMIC SOUND TRANSDUCER

Description

[0001] The invention relates to an electrodynamic sound transducer comprising a transducer cage with at least one air passage, a flexible membrane for sound generation, a magnet system with magnets, a magnetic return path, a pole plate, and an air gap between the pole plate and the magnets, and a voice coil on a substantially cylindrical coil carrier, one end of which extends into the air gap and the other end of which is connected to the membrane. The invention also relates to a land, air, or water vehicle with such a sound transducer.

[0002] A similar sound transducer is already known from the inventor's publication DE 10 2020 001 041 A1, which can be integrated discreetly and space-savingly into the interior paneling of a vehicle. The surface of the interior paneling usually becomes part of the transducer's membrane. However, it has been shown that the desired sound quality could not yet be fully achieved in the design described there.

[0003] Furthermore, a so-called low-cross-section loudspeaker transducer is known from DE 10 2014 115 443 A1. This transducer has a voice coil connected to a separate diaphragm via a form-fitting adapter. The adapter serves to increase the contact or adhesive surface between the voice coil and the diaphragm. However, the separate diaphragm used there has both centering and beads, which stabilize the separate diaphragm, which is not designed as part of a vehicle.

[0004] It is therefore an object of the invention to significantly improve the known type of integrated sound transducer which merges with the interior paneling of a vehicle with regard to its audio quality.

[0005] This problem is solved by the features of the independent patent claims. Advantageous developments of the invention are the subject of subordinate claims. The inventor recognized the following:

[0006] Especially in the automotive and aviation sectors, the integration of the existing sound transducers in the remaining surfaces of the panels in the doors, sides, ceilings and instrument panels is a very big problem, as these are usually relatively deep and heavy and can, above all, visually disrupt the design.

[0007] However, due to the need for acoustic signals and communication in vehicles and for audio quality reasons, the installation of sound transducers is essential. For example, in the automotive sector, tweeters are usually installed in the mirror triangles, A-pillars, or horizontally in the corners of the instrument panels, and in the rear, in the C- or D-pillars or in the trim panels.

[0008] The situation is even more challenging with the deeper, larger-diameter midrange and bass drivers. Here, all speakers must have sufficient space for cabling, a rear cover, adapters, protective grilles, and multiple amplifier channels to transmit the corresponding power.

[0009] In addition, especially in new hybrid and electric vehicles, there is an increasing amount of electronics, batteries, and safety features such as stiffeners and airbags in the doors, instrument panels, rear parcel shelves, and A-, B-, C-, and D-pillars. Therefore, reduced installation space, efficiency, and weight savings are playing an increasingly important role.

[0010] As already described in the document DE 10 2020 001 041 A1, this type of integrated sound transducer features a basket integrated into the supporting structure of a vehicle component, a membrane that uses the surface of the vehicle component to generate sound, without any surround or centering. In other words, the sound transducer merges with the respective vehicle component, for example, with the supporting structure of a panel.

[0011] Compared to the sound transducer described in DE 10 2020 001 041 A1, the inventor recognized that to achieve the goal of improved reproduction, the following elements and components should be fundamentally modified. However, individual changes do not necessarily lead to success, but rather success only results from the interaction of several changes. These elements are essentially: the ring-shaped voice coils with the likewise ring-shaped coil carrier and their attachment to the diaphragm; the central element, which has a connection to the diaphragm; the attachment of the diaphragm to the basket; the diaphragm, in particular its structure and design.

[0012] According to the invention, the coil former of the voice coil is no longer connected directly to the diaphragm, but via a mounting adapter, wherein the mounting adapter is designed to be complementary in shape to the coil former of the voice coil on the voice coil side and complementary in shape to the free-form surface of the diaphragm on the diaphragm side, wherein the basic shape of the contours of the voice coil and mounting adapter - viewed from the front or rear - is preferably also designed differently. The diaphragm can be designed as a free-form surface extending in three dimensions. Furthermore, the mounting adapter should be designed without steps or edges between the coil former of the voice coil and the diaphragm. In addition, the pole plate of the magnet system should be connected centrally and directly to the free-form surface of the diaphragm via a central element. Furthermore, the diaphragm should be connected to the transducer frame via an elastic damper layer.This creates a flexible sandwich connection with an inner foam layer over a circumferential part of the membrane and a circumferential part of the converter basket.

[0013] The improvements of the sound transducer according to the invention essentially improve the following problems with sound transducers of this type in the prior art with regard to standing and reflecting modes, surface resonances and susceptibility to harmonic distortion of the membrane.

[0014] On the basis of the above statements, the inventor proposes the improvement of a known electrodynamic sound transducer, wherein the known sound transducer: a transducer basket with at least one air passage, a flexible membrane, a magnet system with a magnet, a magnetic return, a pole plate, and an air gap between the pole plate and the magnet, a voice coil on a substantially cylindrical coil carrier, which is immersed in the air gap and which is connected to the membrane for sound generation, and a damping central element which is connected to the membrane.

[0015] The improvement according to the invention consists in that: the coil former of the voice coil is connected to the diaphragm via a mounting adapter, the diaphragm is designed as a three-dimensional free-form surface with the exception of conical shapes, the mounting adapter is designed to be complementary in shape to the coil former of the voice coil on the voice coil side and complementary in shape to the free-form surface of the diaphragm on the diaphragm side, the mounting adapter is designed to be stepless between the coil former of the voice coil and the diaphragm, the pole plate of the magnet system is connected centrally and directly via the central element to the free-form surface of the diaphragm, and a damper layer is arranged in the edge region between the diaphragm and the transducer basket.

[0016] It is explicitly stated that the invention does not concern sound transducers with a conical diaphragm. However, if the prior art contains other types of sound transducers with a diaphragm of rotationally symmetrical shape, these are also considered not to be part of the invention.

[0017] Due to the design of the membrane, it is advantageous if the membrane has different thicknesses across its surface. This allows for reinforcement of areas with low dimensional stability, preventing the formation of unwanted vibration modes.

[0018] In particular, the membrane can be made thinner in areas of greater curvature and thicker in areas of lesser curvature.

[0019] It is also particularly advantageous if the diaphragm is thicker in the areas where it is connected to force-transmitting components than in the free areas where no force is transmitted. This reinforces the force-transmitting areas of the diaphragm, particularly the areas connected to the mounting adapter and / or the central element and / or areas of the sandwich-like connection via a foam layer to the cage, to prevent the formation of unwanted spurious vibrations there as well.

[0020] Furthermore, the transducer basket can have a circumferential shoulder where the diaphragm is connected to the transducer basket via the foam layer. The shoulder thus acts as a connecting surface between the transducer basket and the diaphragm, with the elastic foam layer arranged in between.

[0021] Likewise, the transducer basket can have at least one circumferential groove, which prevents resonances and modes from running further outwards and then reflecting.

[0022] It has also been found that it is particularly advantageous if the central element is designed as a single piece, since vibration reflections can occur at the interfaces of multi-piece elements.

[0023] Advantageously, the membrane of the sound transducer can be designed as a single piece and / or as a sandwich.

[0024] Furthermore, the membrane can have at least one convex and at least one concave area, whereby these areas merge smoothly into one another, i.e. to avoid vibration reflections there are only gentle transitions and no steps or edges.

[0025] A particularly advantageous feature of this transducer is the option of coating the diaphragm with a laminated material. This allows the transducer to be covered with the usual coating materials used in automotive engineering, making it virtually "invisible" in the sense that it cannot be detected by the passenger compartment, blending in with the surfaces.

[0026] Furthermore, in a special embodiment, the membrane can have a thickness profile which is thicker in the central fastening area and becomes thinner towards the outside, at least initially.

[0027] The membrane can also have a thickness gradient which is thicker at the fastening area of ​​the mounting adapter and thinner towards the central fastening area.

[0028] Likewise, the membrane can advantageously have a thickness gradient which is thicker at the fastening area of ​​the mounting adapter and thinner towards the surrounding shoulder.

[0029] By integrating the transducer into a vehicle, the membrane can also extend beyond the surrounding heel and the foam layer.

[0030] Furthermore, the membrane can have a thickness profile which increases, at least initially, in the area extending beyond the foam layer.

[0031] It is advantageous for the membrane to have a thickness gradient that is free of steps and has only smooth thickness changes.

[0032] It is also particularly beneficial to avoid unwanted modes if - in each case viewed from the front or rear of the transducer - the outer and / or inner contour of the circumferential shoulder and the outer and / or inner contour of the mounting adapter of the voice coil former differ significantly in terms of their basic shape. As a rule, the voice coil will have a round contour, so the contour of the mounting adapter should be correspondingly non-round. For example, the contour of the mounting adapter can then be rectangular or square, preferably with rounded corners. Advantageously, however, both contours should have at least approximately a congruent center of gravity or a congruent center to avoid the creation of undesired torques on the voice coil.

[0033] In accordance with the previously described feature, it is also proposed that if a circumferential groove is present - in each case viewed from above onto the sound transducer - the outer and / or inner contour of the circumferential groove of the transducer basket and the circumferential outer and / or inner contour of the mounting adapter of the coil former of the voice coil differ significantly with regard to their basic shape.

[0034] Furthermore, it is proposed that if there is a circumferential shoulder on the transducer basket - in each case seen in plan view of the sound transducer - the outer and / or inner contour of the shoulder of the transducer basket and the outer and / or inner contour of the mounting adapter in the area of ​​the connection to the coil carrier and / or in the area of ​​the connection to the diaphragm differ significantly with regard to their basic shape.

[0035] Regarding the design of the magnet system, it is advantageous if an annular copper cap is arranged on the central area of ​​the magnet. The transducer cage of the sound transducer can also advantageously be designed as part of a supporting structure of a land, air, or water vehicle, with the diaphragm being seamlessly integrated into the interior paneling of the vehicle. Furthermore, the transducer cage can be part of a supporting structure of a land, air, or water vehicle, with the diaphragm being seamlessly laminated to the interior paneling of the vehicle.

[0036] The sound transducer according to the invention is designed such that it is free of a bead on the membrane and / or free of a centering for the membrane.

[0037] Furthermore, the sound transducer can particularly preferably be configured such that the voice coil has two separate windings in the same air gap. The windings can be electrically connected in series or parallel, with each being contacted via a single common amplifier channel or via a separate amplifier channel.

[0038] Finally, the sound transducer can also be designed in such a way that the transducer basket is already designed as part of a supporting structure of a vehicle, i.e. the basket is already formed during the manufacture of the supporting structure.

[0039] Furthermore, it is pointed out that within the scope of the invention, the sound transducer can also be designed in a special embodiment such that the membrane has the same thickness throughout and / or its free-form surface has no deformation, i.e. is straight and flat and / or the membrane has no surface lamination.

[0040] The invention is described in more detail below using preferred embodiments with the aid of the figures, in which essentially only the features necessary for understanding the invention are shown. They show in detail: FIG 1: First variant of an integrated sound transducer according to the prior art from DE 10 2020 001 041 A1 in a vertical sectional view; FIG 2: Second variant of an integrated sound transducer according to the prior art from DE 10 2020 001 041 A1 in a vertical sectional view; FIG 3: Integrated sound transducer in a vertical sectional view without lamination of the membrane; FIG 4: Integrated sound transducer in a vertical sectional view with a lamination membrane; FIG 5: Integrated sound transducer in a detailed and sectional view without lamination; FIG 6: Integrated sound transducer in a detailed and sectional view with lamination with shape progression; FIG 7: Integrated sound transducer in the 3D exploded view of a simple integrated version; FIG 8: Integrated sound transducer according to Figure 1in a plan view showing the mode propagation and its disturbances; FIG. 9: integrated sound transducer showing the reduced mode propagation due to the inventive design; FIG. 10: frequency response of the integrated sound transducer measured in the near field according to Figure 1 ; FIG 11: Frequency response measured in the near field of a sound transducer modified according to the invention without cladding; FIG 12: Frequency response measured in the near field of another sound transducer modified according to the invention in a cladding version; FIG 13: Frequency response measured in the near field of another sound transducer modified according to the invention in a cladding version.

[0041] The Figure 1 shows the basis of the integrated transducer according to the publication

[0042] DE 10 2020 001 041 A1 as a flat supporting structure with a transducer cage 1, with webs and air passages 10, the number of which should ideally correspond to a prime number. Mounted in this transducer cage 1 is the magnet system, consisting of at least one magnetic return path 14, a magnet 11, a pole plate 4, and a pole core formed by the return path 14, which may have a surrounding copper or pole cap 5.

[0043] The voice coil is immersed in the air gap of the magnet system, which is formed by the pole plate 4 and the copper cap 5. The voice coil consists of the coil former 8 and the two separate windings 14 and 16 with their electrical contacts 25 and 26. The voice coil former is attached to the underside of the support diaphragm 24. At the center of the magnet system is an elastic central guide damper 12 with its webs and air passages 13, the number of which should also correspond to a prime number. At its center, the central guide damper 12 is connected to the underside of the diaphragm 2 via an elastic central damper 7.

[0044] The Figure 2shows the integrated sound transducer from DE 10 2020 001 041 A1 in a hybrid version with the central guide damper 12, which has additional magnets in the direction of the diaphragm 2, namely a circumferential magnet 17 and a central magnet 20 in the center. In the area inside the coil carrier 8, on the underside of the diaphragm 2, a spiral conductor track 18 is attached, which is also electrically contacted in the same direction at the respective end of the winding. Depending on the application, the contact can be made together with the other contacts 25 and 26, or separately. The double arrow indicates the direction of movement. Furthermore, an elastic, flatter central damper 19 is arranged, which here is located between the central magnet and the diaphragm 2.

[0045] The Figure 3 shows the inventive sound transducer in section and the Figure 5 a detailed extract of the Figure 3 from the area of ​​the magnetic system.

[0046] In this version, the transducer cage 21 is designed to be set back so far that it can be mounted virtually flush with the supporting structure, paneling, and cladding of a vehicle, thus directly transmitting sound. The two dashed lines and double arrows indicate the direction of movement of the voice coil and diaphragm.

[0047] In contrast to the previously known versions of the Figures 1 and 2 the kinetic energy of the voice coil 22 is not introduced directly into the membrane, but via the mounting adapter 24.

[0048] The mounting adapter 24, with its complementary shape to the diaphragm in the mounting area, offers a larger mounting surface to the underside of the diaphragm 22 compared to a direct attachment of a coil carrier, thus better transferring kinetic energy. Furthermore, it prevents the significantly more unstable voice coil 29 with the coils 15, 16 and their coil carrier 8 from becoming deformed or decentered upon contact or indentation of the surface of the diaphragm 22, causing them to drag in the air gap of the magnet system or become jammed, rendering the sound transducer unusable.

[0049] This risk of tilting exists because the air gap of the magnet system, which is formed by the cup-shaped magnetic return 31, the magnet 30 and the pole plate 27, is only a few tenths of a millimeter larger than the voice coil 29.

[0050] A further measure to prevent destruction by contact, pressing in or impact is that the geometry of the transducer basket 21 is designed in such a way that the distance behind the diaphragm to the transducer basket 21 is so narrow that the area outside the voice coil 29 with its mounting adapter 24 is only a few tenths larger than the largest possible amplitude of the diaphragms 22, 39.

[0051] A further improvement concerns the multi-part central guide damper 12 or the central damper 7. It has been found that it is advantageous to use a one-piece central element 28 instead. However, this should be designed to be more rigid, with less damping, and less flexible. This also ensures that pressing in or accidentally impacting the diaphragm 22 does not cause damage. Furthermore, the use of this one-piece central element 28 ensures significantly better ring mode formation, which is clearly confirmed both acoustically and by measurement, as demonstrated by the measurements shown below.

[0052] Another advantageous feature of the new transducer is the embossed contour on one side of the diaphragm surface, preferably on the underside of the diaphragm 22, i.e., the side facing the central element 28 and the mounting adapter 24. The height difference between the embossed contours and the remaining smooth surface is only a few tenths of a millimeter. The material thickness of the diaphragm 22 itself is only slightly thicker than the thinnest remaining area. Thus, in the mounting area of ​​the central element 28, there is a thickening 43 that slopes gently toward the outside before gently rising again to the inner circumferential thickening 40 on the mounting adapter 24.

[0053] Outside the thickening 40 in the mounting area of ​​the mounting adapter 24, the material thickness then becomes gently thinner again until just before the circumferential circumference of the membrane 22 and only shortly before the actual circumferential membrane end does the material thickness increase again, thus forming an impedance termination 41.

[0054] To emboss the membrane, this initially smooth membrane on both sides is placed in a heatable mold and deformed by uniform heating and very high pressure. This influences the polymer chain structure so that, after cooling below its softening point, it assumes and retains the new shape and structure.

[0055] In addition to other possible deformation processes, the one described above can also be used for the membrane 39 designed as a 3D free-form surface, as shown in the Figures 4 and 6 described.

[0056] This ensures that, depending on the frequency and wavelength or amplitude, the ring wave propagation can develop seamlessly and with low reflection attenuation inwardly—that is, between the voice coil 29 with the mounting adapter 24 and the central element 28—and outwardly to the edge. The then thicker, final edge 41 acts as an impedance termination, ensuring that short-wave interference from the edge is reflected back and interferes with the incoming modes.

[0057] A highly integrated concealed version of the transducer is installed in the Figures 4 and 6 shown in a detailed view of the magnet system. Here, the transducer cage 21 structurally merges into the supporting structure of the casing 33 with the foam base 34 and the lamination material 36. The front side of the diaphragm 39 is attached indirectly to the underside of the lamination material 36 via a support film 35 so that it can produce sound.

[0058] The continuously positioned support film 35 prevents the narrow gap formed by the circumferential groove 38 and the circumferentially recessed membrane 39 from becoming permanently visible on the front or outer side of the overlying laminated material 36. This measure is particularly important when using laminated leather, as leather has virtually no surface tension, and this tension changes in moisture or dryness. However, this measure can also be advantageous when lamination with other materials and covering layers.

[0059] Furthermore, the special shape and surface of this variant must be described. In contrast to the versions of the Figures 1 and 2 and those here in the Figures 3 and 5The variants described involve a membrane 39 designed as a three-dimensional freeform surface. This allows such a membrane to blend seamlessly into a given architectural environment of panels or other structural elements. This requirement is primarily required in the automotive sector, but also in other applications, and presents a particular challenge in implementation.

[0060] The mounting adapter 24 and the central element 28 also play a key role in this version of the transducer, regardless of whether it is concave, convex or flat, unclad or clad. The respective adapted surface and material properties of both elements ensure that the ring modes develop in a physically secure manner, that the system functions as a ring mode transducer across the entire frequency range, and that the construction behind the diaphragm 39 is neither visually nor haptically visible on the respective surface of the diaphragm 39 and the cladding materials 36, nor can it be felt. The corresponding protective mechanisms against destruction, as already mentioned above for the Figures 3 and 5 are also applicable in this version.

[0061] A further improved element is the circumferential groove 38, arranged outwardly behind the shoulder 37, in the preferably laminated versions. It has been found that, regardless of whether the membrane is flat, 3D-formed, or of a constant thickness, this membrane 39 must not protrude far beyond the circumferential shoulder 37. In the case of the laminated membrane version, this membrane 39 must not be mounted directly over the circumferential groove 38 with other circumferential or adjacent components, such as the foam base 34 or a supporting structure 33 of the cladding.

[0062] The reason for this is also to avoid reflection of vibrations. The modes or vibrations introduced into the diaphragm 39 must be able to develop beyond the diaphragm end without being reflected. It is important that the diaphragm edge, which is flexibly mounted on the rear side via the one-sided adhesive damper layer 23 to the circumferential shoulder 37 of the transducer cage 21, can still move freely.

[0063] This is shown in the Figure 6 shown in the enlarged illustration in the area of ​​the circumferential groove 38 after the circumferential shoulder 37. Thus, the membrane 39 ends shortly after the circumferential shoulder 37, while the support film 35, laminated with the laminating material 36, extends beyond it and only ends on the foam base 34 of the supporting structure of the cladding 33.

[0064] In the Figure 7An exploded view essentially shows the components that comprise the sound transducer according to the invention. In addition to the parts already described in the preceding figures and texts, reference numeral 42 represents a double-sided adhesive transfer adhesive, which is used to permanently and elastically bond the back of the circumferential damping layer 23 to the circumferential shoulder 37 of the transducer cage 21. However, other alternative bonding techniques are not excluded within the scope of the invention.

[0065] Furthermore, the following parts are shown: the magnetic return 32, the magnet 30, the pole plate 27, the transducer basket 21 with the circumferential shoulder 37, the voice coil 29, the central element 28, the mounting adapter 24, the damper layer 23, which is adhesive on one side in the direction of the diaphragm 22.

[0066] In the Figure 8The problem and origin of vibration modes on the membrane by reflected vibrations are simplified using a top view of a sound transducer according to the Figure 1 shown in a familiar design.

[0067] As from the Figure 2As can be seen, the diaphragm 2 is mounted with a radial damper 3 via the circumferential web with groove 9 to the transducer basket 1. The web with the groove 9 has the same contour, namely circular, in the top view as the coil former 8 with the voice coils 15 and 16 mounted directly on the diaphragm 2. This gives rise to problems with the introduced kinetic energy and the reflected vibrations, which continue as ring modes in the diaphragm between the central damper 7 and the coil former 8 and outside, circumferentially around the coil former 8 via the web with groove 9 to the edge of the diaphragm. However, such modes disrupt the new vibrations introduced via the voice coil.

[0068] These reflections are reflected in the Figure 8 represented by the two double arrow lines with opposing arrows and dashed rings and the modes with the rings with solid lines.

[0069] A solution to this problem is presented in the Figure 9 described, which shows a view of the transducer from the Figure 3 Also shown in a simplified manner by dashed lines is the mounting adapter 24 with voice coil 29, and the central element 28 is positioned centrally within it. The direction of propagation of the ring modes is represented by the two double arrow lines, and the deformation of the ring modes into oval modes is represented by the circular lines.

[0070] Contrary to the statements in the Figures 1, 2 , and 8The transducer cage 21, with its circumferential shoulder 37, on which the diaphragm 22 is mounted above the circumferential damper layer 23, has the shape of a circumferential oval. Thus, the contour of the circumferential shoulder 37 and the circumferential groove 38 differ fundamentally from the contour of the mounting adapter 24. The two contours cannot be made congruent by simply enlarging or reducing them. It has been shown that this use of different basic contours prevents the ring modes, depending on the wavelength, from reflecting from the circular mounting adapter 24 in the mounting area and the edge of the diaphragm 39 in such a way that they interfere with the incoming mode formation.

[0071] Surprisingly, it has also been found that when using such different basic contours for the mounting adapter 24 in the mounting area to the diaphragm 39 in relation to the basic contour of the voice coil former with the voice coil 29, the design of the outer shape of the diaphragm 39 is almost irrelevant while maintaining the same sound quality.

[0072] Even if the diaphragm 39 is also circular like the voice coil 29, the negative influences and interference are kept to a minimum. This is because the returning reflected modes from the diaphragm edge are reflected back toward the outer area of ​​the oval, circumferential shoulder 37 and become dead in the outer area.

[0073] In the following Figures 11 to 13 The influences of various embodiments of the invention in comparison to the prior art are shown in the Figure 10The measurements themselves were conducted in the near field at a distance of 30 cm, without smoothing function, in a small enclosure without a baffle under the same boundary conditions.

[0074] The Figure 10 shows the typical measured frequency response of a sound transducer in the known design according to one of the Figures 1 and 2 The frequencies between 100 Hz and 20 kHz reproduced by the transducer are plotted on the abscissa. The sound pressure level in decibels (dB SPL) is indicated on the ordinate.

[0075] In the Figure 10 one can see clear drops in the frequency response between 200 Hz and 20k Hz, which result from the mode reflections and disturbances of the uniform, in this case circular, design.

[0076] The Figure 11 shows the measurement of the frequency response of the transducer in the version according to the Figures 3 and 5Here you can see a clear improvement and linearization of the amplitude, especially towards the higher frequencies.

[0077] The Figure 12 shows the frequency response of the transducer in a design according to the Figures 4 and 6 In this version, the membrane 39 covered with leather 36 is used with uniform thickness throughout, i.e. without the embossed contour. As a result, the frequency response is Figure 11 smoother and more linear. The slightly higher mass due to the leather lamination results in a slightly lower sensitivity in the midrange between 100 Hz and 2000 Hz, but the level increases significantly towards the high frequencies.

[0078] The Figure 13 also shows the frequency response of the transducer in a design according to the Figures 4 and 6, although in this version, the leather-covered diaphragm 39 features an embossed surface and contour. As a result, the frequency response is even smoother and more linear. In particular, the important midrange between 100 Hz and 2000 Hz is further linearized, and toward the high frequencies, the level of the lower midrange is almost reached.

[0079] Overall, the invention proposes an electrodynamic sound transducer or loudspeaker in which: the coil former of the voice coil is connected to the diaphragm via a mounting adapter, the diaphragm is designed as a three-dimensional free-form surface with the exception of conical shapes, the mounting adapter is designed to be complementary in shape to the coil former of the voice coil on the voice coil side and complementary in shape to the free-form surface of the diaphragm on the diaphragm side, the mounting adapter is designed to be stepless between the coil former of the voice coil and the diaphragm, the pole plate of the magnet system is connected centrally and directly via the central element to the free-form surface of the diaphragm, and the diaphragm is connected flat to the transducer basket via an elastic foam layer.

[0080] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited to the disclosed examples, and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention. In particular, the invention is not limited to the specified combinations of features; rather, other combinations and subcombinations that are obvious to those skilled in the art can also be formed from the disclosed features. List of reference symbols

[0081] 1 Transducer basket 2 Diaphragm 3 Radial damper 4 Pole plate 5 Copper cap 6 Circumferential damper 7 Central damper 8 Coil carrier 9 Circumferential web with groove 10 Air passage 11 Magnet 12 Central guide damper 13 Air passages of the central guide damper 14 Magnetic return path 15 1st coil 16 2nd coil 17 Circumferential magnet 18 Spiral conductor track 19 Flat central damper 20 Central magnet 21 Transducer basket 22 Diaphragm 23 Damper layer 24 Mounting adapter 25 + Electrical contact 26 - Electrical contact 27 Pole plate 28 Central element 29 Voice coil 30 Magnets 31 Magnetic return path 32 Air passage 33 Supporting structure cladding 34 Foam base 35 Supporting film 36 Laminating material 37Circular shoulder 38Circular web with groove 39Membrane 40Thickness of the membrane in the area of ​​the adapter 41Mechanical impedance termination 42Transfer adhesive 43Central fastening area with thickening

Claims

1. Electrodynamic sound transducer, having: - a transducer basket (21) having at least one air passage (32), - a flexible membrane (22), - a magnetic system having a magnet (30), a magnetic back-iron (31), a pole plate (27), and an air gap between the pole plate (27) and the magnet (30), - a voice coil (29) on a substantially cylindrical coil carrier, which dips into the air gap and which is connected to the membrane (22) for generating sound, and - a damping central element (28) which is connected to the membrane (22), wherein - the sound transducer is designed to be free of beads and centrings on the membrane (22). - characterized in that - the coil carrier of the voice coil (29) is connected to the membrane (22) by a mounting adapter (24), - the membrane (22) is configured as a three-dimensional free-form surface except for conical shapes, - the mounting adapter (24) at the voice coil side is complementary in shape to the coil carrier of the voice coil (29) and at the membrane side it is complementary in shape to the free-form surface of the membrane (22), - the mounting adapter is configured without steps between the coil carrier of the voice coil (29) and the membrane (22), - the pole plate (27) of the magnetic system is connected centrally and directly through the central element (28) to the free-form surface of the membrane (22), - and a damper layer (23) is arranged in the marginal region between the membrane (22) and the transducer basket (21).

2. Sound transducer according to the preceding Claim 1, characterized in that the membrane (22) has different thicknesses in the surface.

3. Sound transducer according to the preceding Claim 2, characterized in that the membrane (22) is thicker in regions of connection to force-transmitting components than in free regions with no force transmission.

4. Sound transducer according to one of the preceding claims, characterized in that the transducer basket (21) has an encircling shoulder (37) at which the membrane (22) is connected to the transducer basket (21) via the damper layer (23).

5. Sound transducer according to one of the preceding claims, characterized in that the membrane (22) has at least one convex and at least one concave region, and these regions transition smoothly into one another.

6. Sound transducer according to one of the preceding claims, characterized in that the membrane (22) is coated with a laminating material.

7. Sound transducer according to one of the preceding Claims 4 to 6, characterized in that the membrane (22) extends beyond the encircling shoulder (37) and the damper layer (23).

8. Sound transducer according to one of the preceding Claims 4 to 7, characterized in that - in each case in a top view onto the sound transducer - the outer and / or the inner contour of the encircling shoulder (37) and the outer and / or inner contour of the mounting adapter (24) of the coil carrier of the voice coil (29) differ in regard to their contour in such a manner that the occurrence of undesirable modes during operation is prevented.

9. Sound transducer according to any one of the preceding Claims 4 to 8, characterized in that - in each case in a top view onto the sound transducer - the outer and / or the inner contour of the encircling groove of the transducer basket (21) and the encircling outer and / or inner contour of the mounting adapter (24) of the coil carrier of the voice coil (29) differ in regard to their contour in such a manner that the occurrence of undesirable modes during operation is prevented.

10. Sound transducer according to any one of the preceding Claims 4 to 9, characterized in that - in each case in a top view onto the sound transducer - the outer and / or the inner contour of the encircling shoulder (37) of the transducer basket (21) and the outer and / or inner contour of the mounting adapter (24) in the region of the connection to the coil carrier and / or in the region of the connection to the membrane (22) differ in regard to their contour in such a manner that the occurrence of undesirable modes during operation is prevented.

11. Land, air or water craft having a supporting structure, an inner cladding and at least one sound transducer having a transducer basket (21), characterized in that the sound transducer has the features of one of the preceding Claims 1 to 10, and the transducer basket (21) is part of the supporting structure (33) of the land, air or water craft.

12. Land, air or water craft according to Claim 11, characterized in that the membrane (22) is integrated into the inner cladding of the craft without any transition.

13. Land, air or water craft according to one of Claims 11 or 12, characterized in that the membrane (22) is laminated to the inner cladding of the craft without any transition.