Electrodynamic transducer

Abstract

An electrodynamic sound transducer having a transducer basket, a flexible membrane and a magnetic system having an air gap, a voice coil on a cylindrical coil carrier and a dampening central element, which is connected to the membrane, includes a coil carrier of the voice coil is connected to the membrane by a mounting adapter. The membrane is configured as a three-dimensional free-form surface except for conical shapes.

Claims

1. An electrodynamic sound transducer, having: a transducer basket having at least one air passage, a flexible membrane, a magnetic system having a magnet, a magnetic back-iron, a pole plate, and an air gap between the pole plate and the magnet, a voice coil on a substantially cylindrical coil carrier, which dips into the air gap and which is connected to the membrane for generating sound, and a damping central element, which is connected to the membrane, wherein the coil carrier of the voice coil is connected to the membrane by a mounting adapter, the membrane is configured as a three-dimensional free-form surface except for conical shapes, the mounting adapter at the voice coil side is complementary in shape to the coil carrier of the voice coil and at the membrane side it is complementary in shape to the free-form surface of the membrane, the mounting adapter is configured without steps between the coil carrier of the voice coil and the membrane, the pole plate of the magnetic system is connected centrally and directly through the central element to the free-form surface of the membrane, and a damper layer is arranged in the marginal region between the membrane and the transducer basket.

2. The sound transducer as claimed in claim 1, wherein the membrane has different thicknesses in the surface.

3. The sound transducer as claimed in claim 2, wherein the membrane is thinner in regions of greater curvature and thicker in regions with less curvature.

4. The sound transducer as claimed in claim 2, wherein the membrane is thicker in regions of connection to force-transmitting components than in free regions with no force transmission.

5. The sound transducer as claimed in claim 1, wherein the transducer basket comprises an encircling shoulder, at which the membrane is connected to the transducer basket via the damper layer.

6. The sound transducer as claimed in claim 1, wherein the transducer basket comprises at least one encircling groove.

7. The sound transducer as claimed in claim 1, wherein the central element is formed single-piece.

8. The sound transducer as claimed in claim 1, wherein the membrane is formed single-piece.

9. The sound transducer as claimed in claim 1, wherein the membrane is formed sandwich-like.

10. The sound transducer as claimed in claim 1, wherein the membrane has at least one convex and at least one concave region and these regions pass smoothly into one another.

11. The sound transducer as claimed in claim 1, wherein the membrane is coated with a laminating material.

12. The sound transducer as claimed in claim 1, wherein the membrane has a thickness gradient which is thicker at a central fastening region and becomes thinner toward the outside at least at first.

13. The sound transducer as claimed in claim 1, wherein the membrane has a thickness gradient which is thicker at a fastening region of the mounting adapter and becomes thinner toward a central fastening region.

14. The sound transducer as claimed in claim 5, wherein the membrane has a thickness gradient which is thicker at the fastening region of the mounting adapter and becomes thinner toward the encircling shoulder.

15. The sound transducer as claimed in claim 5, wherein the membrane extends beyond the encircling shoulder and the damper layer.

16. The sound transducer as claimed in claim 15, wherein the membrane has a thickness gradient which increases at least initially in the region going beyond the damper layer.

17. The sound transducer as claimed in claim 1, wherein the membrane has a thickness gradient which is free of shoulders and only has very gradual thickness changes (pitch angle <10).

18. The sound transducer as claimed in claim 5, whereineach time looking in a top view onto the sound transducerthe outer and/or inner contour of the encircling shoulder and the outer and/or inner contour of the mounting adapter of the coil carrier of the voice coil are significantly different in regard to their basic shape.

19. The sound transducer as claimed in claim 6, whereineach time looking in a top view onto the sound transducerthe outer and/or inner contour of the encircling groove of the transducer basket and the encircling outer and/or inner contour of the mounting adapter of the coil carrier of the voice coil are significantly different in regard to their basic shape.

20. The sound transducer as claimed in claim 5, whereineach time looking in a top view onto the sound transducerthe outer and/or inner contour of the encircling shoulder of the transducer basket and the outer and/or inner contour of the mounting adapter in the region of the connection to the coil carrier and/or in the region of the connection to the membrane are significantly different in regard to their basic shape.

21. The sound transducer as claimed in claim 1, wherein a ring-shaped copper cap is arranged on the central region of the magnet.

22. The sound transducer as claimed in claim 1, wherein the transducer basket is part of a support structure of a land, air, or water vehicle and the membrane is integrated seamlessly in the interior paneling of the vehicle.

23. The sound transducer as claimed in claim 1, wherein the transducer basket is part of a support structure of a land, air, or water vehicle and the membrane is laminated seamlessly with the interior paneling of the vehicle.

24. The sound transducer as claimed in claim 1, wherein the sound transducer is free of a bead on the membrane.

25. The sound transducer as claimed in claim 1, wherein the sound transducer is free of a centering for the membrane.

26. The sound transducer as claimed in claim 1, wherein the voice coil comprises two separate windings in the same air gap, being electrically contacted in series or in parallel by the same or each by their own amplifier channel.

27. The sound transducer as claimed in claim 1, wherein the transducer basket is designed as part of a support structure of a vehicle.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0057] In the following, the invention is described more closely on the basis of preferred exemplary embodiments with the aid of the figures, where substantially only the features necessary to understand the invention are represented. There are shown, specifically:

[0058] FIG. 1: First variant of an integrated sound transducer according to the prior art of PCT/DE2021/000031 in a vertical cross-sectional representationsection A-A of FIG. 8;

[0059] FIG. 2: second variant of an integrated sound transducer according to the prior art of PCT/DE2021/000031 in a vertical cross-sectional representationsection A-A of FIG. 8;

[0060] FIG. 3: integrated sound transducer in a vertical cross-sectional representation without lamination of the membranesection A-A of FIG. 9;

[0061] FIG. 4: integrated sound transducer in a vertical cross-sectional representation with a membrane having laminationsection A-A of FIG. 9;

[0062] FIG. 5: integrated sound transducer in a detail - and cross-sectional representation without laminationdetail section A-A of FIG. 9;

[0063] FIG. 6: integrated sound transducer in a detailand cross-sectional representation with lamination with shape gradientdetail section A-A of FIG. 9;

[0064] FIG. 7: integrated sound transducer in the 3D exploded representation of a simple integrated version;

[0065] FIG. 8: integrated sound transducer per FIG. 1 in a top view showing the mode propagation and its interferencesprior art;

[0066] FIG. 9: integrated sound transducer showing the reduced mode propagation thanks to the configuration according to the invention;

[0067] FIG. 10: the frequency response, measured in the near field, of the integrated sound transducer per FIG. 1prior art;

[0068] FIG. 11: the frequency response, measured in the near field, of a sound transducer without lamination modified according to the invention;

[0069] FIG. 12: the frequency response, measured in the near field, of another sound transducer of laminated configuration modified according to the invention;

[0070] FIG. 13: the frequency response, measured in the near field, of another sound transducer of laminated configuration modified according to the invention.

DETAILED DESCRIPTION OF INVENTION

[0071] FIG. 1 shows the basis of the integrated sound transducer according to document PCT/DE2021/000031 as a flat support construction with a transducer basket 1, having webs and air passages 10, the number of which should correspond as much as possible to a prime number. Mounted in this transducer basket 1 is the magnetic system, consisting of at least one magnetic back-iron 14, a magnet 11, a pole plate 4 and a pole core, formed by the back-iron 14, which can have a surrounding copper or pole cap 5.

[0072] The voice coil dips into the air gap of the magnetic system, which is formed by the pole plate 4 and the copper cap 5. The voice coil consists of the coil carrier 8 and the two separate windings 14 and 16 with their electrical contacting points 25 and 26. The voice coil carrier is fastened on the underside of the support membrane 24. At the center of the magnetic system is situated an elastic central guide damper 12 with its webs and air passages 13, the number of which should likewise correspond to a prime number. At its center, the central guide damper 12 is connected across an elastic central damper 7 to the underside of the membrane 2.

[0073] FIG. 2 shows the integrated sound transducer from PCT/2021/000031 in a hybrid version with the central guide damper 12, which comprises further magnets in the direction of the membrane 2, namely an encircling magnet 17 and at the center a central magnet 20. In the region inside the coil carrier 8, on the underside 10 of the membrane 2, there is attached a spiral conductor track 18, which is also electrically contacted in the same direction at the respective end of the winding. Depending on the application, the contacting can be done jointly with the other contacts 25 and 26, but also separately. The double arrow shows the direction of movement. Furthermore, an elastic and shallower central damper 19 is arranged, being located here between the central magnet and the membrane 2.

[0074] FIG. 3 shows the sound transducer according to the invention in the cross section and FIG. 5 shows a detail cutout of FIG. 3 from the region of the magnetic system.

[0075] In this embodiment, the transducer basket 21 is configured such that it is set back so far that it can be mounted with the support structure, the paneling and the lamination of a vehicle virtually flush with the baffle and thus transmits the sound directly. The two broken lines and double arrows indicate the direction of movement of the voice coil and the membrane.

[0076] By contrast with the previously known configurations of FIGS. 1 and 2, the kinetic energy of the voice coil 22 is not introduced directly into the membrane, but instead through the mounting adapter 24.

[0077] The mounting adapter 24 thanks to a configuration which accordingly is complementary in shape to the membrane in the fastening region, offers an increased fastening surface, as compared to a direct mounting of a coil carrier, on the underside of the membrane 22 and therefore transmits the kinetic energy in a better way. On the other hand, when the surface of the membrane 22 is touched or pressed in, this prevents the much less stable voice coil 29 with the coils 15, 16 and their coil carrier 8 from being able to be deformed or moved off center such that they are dragged in the air gap of the magnetic system or become jammed so that the sound transducer can no longer be used.

[0078] This danger of jamming exists because the air gap of the magnetic system, which is formed by the pot-shaped magnetic back-iron 31, the magnet 30 and the pole plate 27, is also only a few tenths of a millimeter larger than the voice coil 29 around its periphery.

[0079] A further way of preventing a disruption due to touching, pressing, or bumping is to configure the geometry of the transducer basket 21 such that the distance behind the membrane up to the transducer basket 21 is so slight that the region outside of the voice coil 29 with its mounting adapter 24 is only a few tenths larger than the largest possible amplitude of the membrane 22, 39.

[0080] A further improvement relates to the multipiece central guide damper 12 or the central damper 7. It has been discovered that it is advantageous to use instead of this a single-piece central element 28. But this should be stronger and less dampening and less movable in its design here. This also ensures that no damage is caused by pressing in or accidentally bumping against the membrane 22. Furthermore, thanks to the use of said single-piece central element 28, a much better ring mode formation is assured, which is also proven acoustically and by measurements, as proven by the measurements shown below.

[0081] A further advantageous property of the new sound transducer is the embossing of a contour on the surface of the membrane on one side, preferably on the underside, i.e., the side of the membrane 22 facing the central element 28 and the mounting adapter 24. The height difference of the embossing as compared to the surface remaining smooth is only a few tenths of a millimeter here. The material thickness of the membrane 22 itself is only slightly thicker than the thinnest remaining region here. Thus, in the mounting region of the central element 28 there is a thickening 43, which gently diminishes toward the outside, in order then to again increase gently up to the inner peripheral thickening 40 on the mounting adapter 24.

[0082] Outside the thickening 40 in the mounting region of the mounting adapter 24, the material thickness again becomes gently thinner until just before the encircling periphery of the membrane 22 and only just before the actual encircling membrane end does the material thickness again increase and thereby forms an impedance termination 41.

[0083] For the embossing of the membrane, said membrane originally smooth on both sides is placed in a corresponding heatable mold and deformed by uniform heating and very high pressure. The polymer chain structure is influenced here such that, after cooldown below the softening point, the new shape and structure is assumed and preserved by said structure.

[0084] Besides other possible deformation processes, the one described above can also be used for the membrane 39 configured as a 3D free-form surface, as will be described in FIGS. 4 and 6.

[0085] This produces the effect that the ring wave propagation can be formed in uninterrupted and low-reflection dampening fashion toward the insidei.e., between the voice coil 29 with the mounting adapter 24 and the central element 28 and to the outside as far as the margin, depending on the frequency and wavelength, or the amplitude. The now thicker terminating margin 41 acts here like an impedance termination and ensures that short-wave perturbations are reflected back from the margin and disrupt the then arriving modes.

[0086] A highly integrated laminated version of the sound transducer is shown in FIGS. 4 and 6 in a detail representation in the region of the magnetic system. Here, the transducer basket 21 passes structurally into the support structure of the paneling 33 with the foam base 34 and the laminating material 36, wherein the front side of the membrane 39 is attached across a support film 35 indirectly with the underside of the laminating material 36 so that it can produce sound.

[0087] The continuously positioned support film 35 prevents the narrow gap formed by the encircling groove 38 and the membrane 39, which is set back in encircling fashion, from emerging in optically long-lasting fashion on the front or outer side of the laminating material 36 coated on top of it. This step is important primarily when using laminated leather, since leather has virtually no surface tension at all and still undergoes change when conditions are humid or dry. But this step can also be advantageous in the case of lamination with other materials and cover layers.

[0088] Furthermore, the special shape and surface of this variant should be described. Unlike the embodiments of FIGS. 1 and 2 and the variants described here in

[0089] FIGS. 3 and 5, this involves a membrane 39 which is formed as a three-dimensional free-form surface. Thus, such a membrane can be incorporated seamlessly in a given architectural setting of paneling or other components. This requirement is required primarily in the automotive industry, but also in other applications, and constitutes a special challenge in implementation.

[0090] The mounting adapter 24 and the central element 28 also play a load-bearing role in this version of the sound transducer, whether concave, convex, or flat, whether laminated or unlaminated. The respectively adapted surface and material properties of the two elements ensure that the ring modes are formed in a physically secure manner, that the system functions as a ring mode converter over the entire frequency range, and the construction behind the membrane 39 is neither optically nor haptically evident or becomes perceptible on the respective surface of the membrane 39 and the laminating materials 36. The corresponding protection mechanisms against a disruption, as already described above for FIGS. 3 and 5, can also be used in this version.

[0091] Another improved element is the encircling groove 38, arranged outwardly behind the shoulder 37, in the preferably laminated versions. It has been discovered that, whether with a flat, a 3D-deformed, or a membrane of uniform thickness, this membrane 39 should not extend far beyond the encircling shoulder 37. In the case of the laminated membrane version, this membrane 39 should not be mounted directly beyond the encircling groove 38 with other encircling or adjoining components, such as the foam base 34 or a support structure 33 of the paneling.

[0092] The reason for this as well is that the reflection of oscillations is to be avoided. The modes or oscillations introduced into the membrane 39 must be formed beyond the membrane end without being reflected. It is important for the membrane margin, which is mounted flexibly on the encircling shoulder 37 of the transducer basket 21 on the back side across the one-sided adhesive damper layer 23, to still be able to move freely.

[0093] This is shown in FIG. 6 with the aid of the enlarged representation in the region of the encircling groove 38 after the encircling shoulder 37. Thus, the membrane 39 ends shortly after the encircling shoulder 37, while the support film 35 laminated with the laminating material 36 runs beyond this and only ends on the foam base 34 of the support structure of the paneling 33.

[0094] FIG. 7 shows an exploded drawing of basically the components making up the sound transducer according to the invention. In addition to the parts already described in the preceding figures and texts, a two-sided transfer adhesive is shown here with the reference number 42, by which the back side of the encircling damper layer 23 is permanently elastically mounted with the encircling shoulder 37 of the transducer basket 21. Other alternative gluing techniques, however, are not ruled out in the context of the invention.

[0095] Furthermore, the following parts are shown: the magnetic back-iron 32, the magnet 30, the pole plate 27, the transducer basket 21 with the encircling shoulder 37, the voice coil 29, the central element 28, the mounting adapter 24, the damper layer 23, being adhesive on one side in the direction toward the membrane 22.

[0096] In FIG. 8, the problems and the formation of the oscillation modes on the membrane by reflecting oscillations are shown in simplified manner with the aid of a top view of a sound transducer in known configuration according to FIG. 1.

[0097] As can be seen from FIG. 2, the membrane 2 is mounted with a radial damper 3 via the encircling web with groove 9 with the transducer basket 1. The web with the groove 9 has the same contour in the top view, namely, circular round, as the coil carrier 8 with the voice coils 15 and 16 mounted directly on the membrane 2. This causes problems with the introduced kinetic energy and the reflected oscillations, which are propagated as ring modes in the membrane between the centrally located central damper 7 and the coil carrier 8 and externally surrounding the coil carrier 8 beyond the web with the groove 9 as far as the membrane edge. However, such modes disturb the new oscillations introduced through the voice coil.

[0098] These reflections are shown in FIG. 8 by the two double arrow lines with opposite arrows and dashed rings, and the modes with the rings are shown by solid lines.

[0099] One solution approach to this problem is described in FIG. 9, representing a top view of the sound transducer from FIG. 3. The central element 28 can be seen, likewise represented for simplicity by broken lines, situated at the center of the mounting adapter 24 with the voice coil 29 and placed centrally therein. The mode propagation direction of the ring modes is shown by the two double arrow lines and the deforming of the ring modes into oval modes is shown by the circular lines.

[0100] By contrast with the embodiments in FIGS. 1, 2, and 8, the transducer basket 21 with its encircling shoulder 37, on which the membrane 22 is mounted across the encircling damper layer 23, has more the shape of an encircling oval. Thus, the contour of the encircling shoulder 37 and the encircling groove 38 differs fundamentally from the contour of the mounting adapter 24. Thus, the two contours cannot be made congruent by simple enlarging or reducing. It has been found that this use of different basic contours prevents the ring modes from being reflected such that they disturb the incoming mode formation in dependence on the wavelength, starting from the circular round mounting adapter 24 in the mounting region and the margin of the membrane 39.

[0101] Surprisingly, it has also been discovered that, by using such different basic contours for the mounting adapter 24 in the mounting region for the membrane 39 in relation to the basic contour of the voice coil carrier with the voice coil 29, the configuration of the outer shape of the membrane 39 is almost insignificant, for the same sound quality.

[0102] Even if the membrane 39 is likewise circular round in configuration, like the voice coil 29, the negative influences and perturbations are greatly held in check. This is due to the fact that the reflected modes returning from the membrane margin are reflected back toward the outer region of the oval encircling shoulder 37 and die down in the outer region.

[0103] In the following FIGS. 11 to 13, the influences of various exemplary embodiments according to the invention are presented by measurements as compared to the prior art in FIG. 10. The measurements themselves were taken in the near field at 30 cm distance, with no smoothing function, in a small housing without a baffle, under the same boundary conditions.

[0104] FIG. 10 shows the typical measured frequency response of a sound transducer in the known configuration according to one of FIGS. 1 and 2. Plotted along the abscissa are the frequencies between 100 Hz and 20 kHz, which are rendered by the sound transducer. Along the ordinate is plotted the sound pressure level in decibels (dB SPL).

[0105] In FIG. 10 one can notice distinct drops in the frequency response between 200 Hz and 20 kHz, which are due to the mode reflections and disruptions of the uniform configuration, being circular round in this case.

[0106] FIG. 11 shows the measurement of the frequency response of the sound transducer in the embodiment of FIGS. 3 and 5. One notices here a distinct improvement and linearization of the amplitude, especially toward the higher frequencies.

[0107] FIG. 12 shows the frequency response of the sound transducer in an embodiment according to FIGS. 4 and 6. In this version, the membrane 39 laminated with leather 36 and having the same thickness throughout is used, i.e., without the embossed contour. As a result, the frequency response is more smooth and linear as compared to FIG. 11. While the somewhat greater weight of the leather lamination appears in somewhat less sensitivity in the middle tone region between 100 Hz and 2000 Hz, the level increases significantly toward the high frequencies.

[0108] FIG. 13 shows the frequency response of the sound transducer in an embodiment according to FIGS. 4 and 6, but in this version the membrane 39 laminated with leather 36 has an embossed surface and contour. As a result, the frequency response becomes even more smooth and linear. In particular, the important middle tone region between 100 Hz and 2000 Hz is linearized even more and the level of the lower middle tone region is nearly reached toward the high frequencies.

[0109] On the whole, therefore, the invention proposes an electrodynamic sound transducer or loudspeaker in which: [0110] the coil carrier of the voice coil is connected to the membrane by a mounting adapter, [0111] the membrane is configured as a three-dimensional free-form surface except for conical shapes, [0112] the mounting adapter at the voice coil side is complementary in shape to the coil carrier of the voice coil and at the membrane side it is complementary in shape to the free-form surface of the membrane, [0113] the mounting adapter is configured without steps between the coil carrier of the voice coil and the membrane, [0114] the pole plate of the magnetic system is connected centrally and directly through the central element to the free-form surface of the membrane, [0115] and the membrane is connected in two dimensions to the transducer basket across an elastic foam layer.

[0116] Although the invention has been described and illustrated more closely in detail by the preferred exemplary embodiment, the invention is not limited by the disclosed examples and other variations can be derived from it by the person skilled in the art, without leaving the protection scope of the invention. In particular, the invention is not limited to the indicated combinations of features, but rather other combinations and partial combinations which can be implemented in a way obvious to the skilled person can also be formed from the disclosed features. Thus, implementations which are not explicitly shown in the figures, yet which emerge from and can be created from the explained embodiments by separate combinations of features, should also be deemed to be encompassed and disclosed by the invention. It also lies within the scope of the invention to produce a mechanical reversal of the functions of the individual mechanical elements of the invention.

List of reference numbers

[0117] 1 Transducer basket [0118] 2 Membrane [0119] 3 Radial damper [0120] 4 Pole plate [0121] 5 Copper cap [0122] 6 Encircling damper [0123] 7 Central damper [0124] 8 Coil carrier [0125] 9 Encircling web with groove [0126] 10 Air passage [0127] 11 Magnet [0128] 12 Central guide damper [0129] 13 Air passages of the central guide damper [0130] 14 Magnetic back-iron [0131] 15 1st coil [0132] 16 2nd coil [0133] 17 Encircling magnet [0134] 18 Spiral conductor track [0135] 19 Shallower central damper [0136] 20 Central magnet [0137] 21 Transducer basket [0138] 22 Membrane [0139] 23 Damper layer [0140] 24 Mounting adapter [0141] 25 + electrical contacting [0142] 26 electrical contacting [0143] 27 Pole plate [0144] 28 Central element [0145] 29 Voice coil [0146] 30 Magnets [0147] 31 Magnetic back-iron [0148] 32 Air passage [0149] 33 Cladding support structure [0150] 34 Foam base [0151] 35 Support film [0152] 36 Laminating material [0153] 37 Encircling shoulder [0154] 38 Encircling web with groove [0155] 39 Membrane [0156] 40 Thickness gradient of membrane in the region of the adapter [0157] 41 Mechanical impedance termination [0158] 42 Transfer adhesive [0159] 43 Central fastening region with thickening