Planar dynamic converter

Abstract

Planar dynamic transducer (200) comprising a first planar magnet arrangement (220), a fastening element (221, 321) and a diaphragm (240) with conductor tracks (245) and at least one diaphragm support frame (250), wherein the diaphragm support frame is clamped between the magnet arrangement and the fastening element, wherein at least one decoupling element (260) made of elastic material is located between the membrane support frame (250) and the first magnet arrangement (220) and / or between the membrane support frame (250) and the fastening element (221, 321), wherein the first magnet arrangement (220) and the fastening element (221) are connected to each other by a screw, rivet or press connection (280), wherein the screw, rivet or press connection (230) does not pass through the membrane support frame (250), and wherein the screw, rivet or press connection (280) lies substantially in the plane of the membrane (240) or parallel to the plane of the membrane and the magnet arrangement (220) and the fastening element (221,321) have at least one overlap (270) through which the screw, rivet or press connection (280) is guided.

Description

[0001] The invention relates to a planar dynamic transducer, in particular a planar dynamic sound transducer. background

[0002] Planar dynamic transducers typically consist of a magnet array with several parallel magnet bars and a diaphragm, where the plane of the magnet array is parallel to the diaphragm plane. In sound reproduction mode, an electric current flows through a planar coil mounted directly on the diaphragm. The magnetic field of the magnet array generates a deflection force, which moves the diaphragm and thus produces sound. In sound recording mode, i.e., as a microphone, the sound excitation of the diaphragm induces a corresponding electric current in the coil. Conventional planar dynamic transducers employ a sandwich construction with stacked components.

[0003] Planar dynamic transducers often have a symmetrical design, meaning two identical magnet arrangements mirrored at the diaphragm plane. This creates significant repulsive forces between the two magnet arrangements. These forces, along with the connecting elements required for their fixation (e.g., brackets, mounts, screws, clamps, etc.), can cause twisting, deflection, distortion, screw torque, and other issues. The entire assembly of magnets and associated components is referred to here as the "magnetic components."

[0004] Conventionally, the membrane film is either fixed directly to the appropriately shaped magnetic holder or to a separate component (e.g., a support frame or ring) to facilitate its processing (treatment, coating, structuring, contacting, etc.) and ensure good flatness. This component also often serves as a spacer to other components. The gap on the other side of the membrane can be created by another component (e.g., a spacer frame or ring) or by appropriately shaping adjacent components.

[0005] The entirety of the membrane and its associated components is referred to here as "membrane components".

[0006] Some well-known implementations of planar dynamic transducers use a predominantly or completely rigid connection between the magnet components and the diaphragm components. An exemplary cross-section is shown in Fig. Figure 1 shows the magnetic components. These include, for example, the magnet assembly 120 with bar magnets 110 and a holder 120a, as well as a screw connection 130. The membrane components include, for example, the membrane film 140 with conductor tracks 145 and a membrane support frame 150.

[0007] Since the magnetic components are generally at least as strong or rigid as the diaphragm components, especially the support frame 150, the aforementioned stresses, twists, deflections, etc., are transferred to the very thin, prestressed diaphragm film 140 and impair its flatness and / or the homogeneity of the mechanical stress. This can lead to undesirable, suboptimal vibration behavior and acoustic disadvantages such as partial vibrations, uneven frequency response, harmonic distortion, and so on.

[0008] Several solutions for acoustically decoupling the diaphragm of planar transducers are known. US 3,066,200 A describes how the corners of a diaphragm are glued directly to padding elements, which are glued to posts to keep the transducer particularly small. EP 0 116 957 A1 discloses a ribbon loudspeaker diaphragm whose edge is surrounded by adhesive foam strips and clamped directly between frame-like tensioning elements, tensioned by screws and springs. WO 99 / 0026451 A1 describes how a diaphragm can, in principle, move freely across its entire surface in the vertical direction, being damped by damping elements and guided at the corners by screws. US 4,803,733 A discloses a method for tensioning a diaphragm during transducer assembly, clamping it between two partial frames using a tensioning element.US 5,430,805 A describes a planar transducer with a multilayer diaphragm that is clamped between two subframes using double-sided adhesive tape. US 2004 / 0086147 A1 shows a design whose magnet system, similar to that of moving-coil transducers, has a yoke, but the coil is applied as a flat conductor track on the diaphragm; this is surrounded at the edge with padding material and clamped between the yoke and the outer housing. Summary of the invention

[0009] One object of the present invention is to provide an improved planar dynamic transducer in which, in particular, the problems mentioned above do not occur. According to the invention, this object is achieved by decoupling the diaphragm components from the magnet components.

[0010] A sound transducer according to the invention is specified in claim 1.

[0011] According to the invention, a planar dynamic transducer comprises a first planar magnet arrangement, a fastening element, and a diaphragm with conductive traces and at least one diaphragm support frame, wherein the diaphragm support frame is clamped between the magnet arrangement and the fastening element, and wherein at least one decoupling element made of elastic material is located between the diaphragm support frame and the first magnet arrangement and / or between the diaphragm support frame and the fastening element. The first magnet arrangement and the fastening element are connected to each other by a screw, rivet, or press connection that does not pass through the diaphragm support frame but is guided substantially parallel to the plane of the diaphragm by an overlap of the first magnet arrangement with the fastening element. The fastening element can also be a second planar magnet arrangement.

[0012] Further advantageous embodiments are described in claims 2-6.

[0013] Claims 7 and 8 relate to a headphone and a microphone with a planar dynamic sound transducer according to the invention. Brief description of the drawings

[0014] Further details and advantageous embodiments are shown in the drawings. These show Fig. 1 a cross-section through a known planar dynamic sound transducer; Fig. 2 a cross-section through a two-sided improved planar dynamic transducer according to a first embodiment; Fig. 3 a cross-section through a two-sided improved planar dynamic sound transducer according to a second embodiment of the invention; Fig. 4 a cross-section through a one-sided improved planar dynamic transducer according to one embodiment; Fig. 5 an elastic element for clamping the membrane frame according to one embodiment; and Fig. 6 a perspective view of a two-sided improved planar dynamic sound transducer according to the second embodiment of the invention. Detailed description of the invention

[0015] Fig. Figure 2 shows a cross-section through a two-sided improved planar dynamic transducer according to a first embodiment. The planar dynamic transducer 200 comprises a planar first magnet arrangement 220, consisting of bar magnets 210 and a frame element 220a for mounting the bar magnets, and a second, mirror-symmetrical magnet arrangement 221, which also consists of bar magnets 211 and a frame element 221a. The magnet arrangements 220 and 221 are, by way of example, firmly connected to one another by a screw connection 230. Other connection methods, such as clamps, are also possible.The mechanical, force-bearing connection between the magnetic components (here: bar magnets 210, frame elements 220a and 221a, screw connection 230), in particular the connection between the two symmetrically opposed component groups, is partially or completely mechanically decoupled from the membrane components (here: membrane film 240 with conductor tracks 245, membrane support frame 250). This is achieved by directly connecting the magnetic components to each other and clamping the membrane film with the membrane support frame 250 between the two magnet arrangements 220, 221, with a decoupling element 260 made of elastic material located between the membrane support frame 250 and the magnet arrangements 220, 221. Thus, there is no rigid connection between the magnetic components and the membrane components.

[0016] The (partial) decoupling of the diaphragm components from the magnet components is improved by a sufficiently thick layer of an elastic material 260, e.g., an elastomer, elastic foam, silicone adhesive, or an elastic adhesive film. Alternatively, the material 260 can also be a viscous material, such as an adhesive, which cures to a partially or completely elastic final state after assembly of the transducer. This compensates for any unevenness, warping, or tolerance of the magnet components and simultaneously minimizes the force acting on the diaphragm components. Any further deformations of the magnet components that may occur later can be accommodated by elastic deformation of the material 260. Alternatively, the material 260 can also be a viscoelastic material (e.g., "memory foam," shape-memory polymer, etc.).The material should exert a similarly low force on the membrane components as a viscous material, but without being a liquid. This makes it easier to handle, dose, and position. The layer is sufficiently thick to ensure the correct positioning of the membrane components relative to the magnetic components. Depending on the chosen elastic material, the decoupling is stronger, weaker, or only partial. Any twisting or similar movements are absorbed by the elastic layer and largely or completely compensated, thus minimizing or preventing their transmission to the membrane. This results in greater flatness and improved vibration behavior.

[0017] A cross-section through a two-sided improved planar dynamic transducer according to a second embodiment of the invention is shown in Fig. Figure 3 illustrates this. In contrast to the first embodiment, the connection between the two opposing magnet arrangements 220, 221 is not achieved by a screw 230 lying substantially perpendicular to the plane of the diaphragm, but rather by an axial connection 280, which lies substantially in the plane of the diaphragm 240. This connection can be, for example, a screw, rivet, or press fit. The first magnet arrangement 220 and the second magnet arrangement 221, which is substantially mirror-symmetrical to it, have at least one overlap 270 or interlocking joint (e.g., according to the tongue-and-groove principle) through which the connecting axis 280 is guided. At least in the area of ​​the overlap or interlocking joint 270, the first magnet arrangement 220 and the second magnet arrangement 221 may not be mirror-symmetrical.It is particularly advantageous to design the axial connection 280 to be movable in such a way that the two magnet arrangements 220, 221 can spread apart from each other. In this variant, under the influence of the magnetic repulsive forces and corresponding (usually slight) deformation of the magnet arrangements 220, 221, a (minimal) rotation about the axis of the connection 280 is possible, whereby the resulting tensile stresses are not concentrated on one side and at a single point, but are distributed over the entire thickness or length of the supporting component. This reduces the stress on the magnet arrangements 220, 221 and the frames 220a, 221a, allowing them to be made correspondingly smaller. This saves material and reduces the weight of the transducer.

[0018] Fig. Figure 4 shows, according to one embodiment, a cross-section through an improved single-sided planar dynamic transducer. The second magnet arrangement 221 described above is replaced by a fastening element 321, which has fewer or no bar magnets and may have a different thickness and / or shape than the first magnet arrangement 220. The first magnet arrangement 220 is as described in the embodiment above. Single-sided planar dynamic transducers have a flatter design than double-sided transducers and make the diaphragm more accessible for sound input and output. However, they are less effective due to the lower magnetic field strength and generate harmonic distortion due to the asymmetrical magnetic field. The main purpose of the fastening element 321 here is to hold the diaphragm components 240, 245, 250 by clamping the diaphragm support frame 250 between the first magnet arrangement 220 and the fastening element 321.Between the membrane support frame 250 and the first magnet arrangement 220 and / or between the membrane support frame 250 and the fastening element 321, there is at least one decoupling element 260 made of elastic material, as described above. As in the other embodiments, the elastic material of the fastening element 321 can decouple the membrane components from mechanical stresses in the frame and compensate for unevenness in the frame and / or in the magnet arrangements 220, 221 or in the fastening element 321.

[0019] In the Fig. In the example shown in Figure 4, the first magnet arrangement 220 and the fastening element 321 are connected by a screw perpendicular to the membrane, as in the first embodiment above. However, the first magnet arrangement 220 and the fastening element 321 can also be connected by other methods, such as clamps, or by an axial connection parallel to the membrane, as shown above in the second embodiment in connection with Fig. 3 described.

[0020] The decoupling of the membrane according to the invention represents a construction method that differs significantly from the conventional sandwich construction: Fig. Figure 5 shows an elastic decoupling element 260 for clamping the membrane film 240 and the membrane support frame 250 according to various embodiments. The decoupling element 260 wraps around the edge of the membrane 240 and the membrane support frame 250, thus mechanically separating them from the first magnet arrangement 220 and the second magnet arrangement 221, or the fastening element 321. Fig. 5a) A single decoupling element 260 is used. Alternatively, two or more separate decoupling elements can be used, e.g., one above the membrane, one below the membrane, and one at the outer edge. In one embodiment, the membrane or the membrane support frame is completely surrounded by the decoupling element in the membrane plane. When using multiple decoupling elements, however, they do not necessarily have to completely surround the membrane or the membrane support frame, but only ensure reliable decoupling and fix the membrane components. This must also be ensured in the case of the spreading described above. For example, in Fig. 5b) the decoupling element 260 is narrower than the membrane support frame 250. Fig. 5c) shows in top view a membrane 240 with membrane support frame 250, which is not completely surrounded in the membrane plane by the decoupling element 260".

[0021] Fig. Figure 6 shows a perspective view of the improved two-sided planar dynamic transducer according to the second embodiment of the invention. As described above, the first and second magnet arrangements 220, 221 are connected to each other by an axial connection 280 and have at least one overlap 270 or interlocking through which the axial connection 280 is guided. An advantage of the invention is that homogeneous diaphragm tension, and thus better playback / recording quality, is easier to achieve. The magnet arrangements can be smaller because the requirements for the stiffness and flatness of the mechanical components are not as stringent as in conventional planar dynamic transducers. In contrast to the one described in Figure 6, the magnet arrangements can be smaller because the requirements for the stiffness and flatness of the mechanical components are not as stringent as in conventional planar dynamic transducers. Fig. In the planar transducer design according to the invention, the holes in the membrane components are also eliminated in the conventional transducer shown in Figure 1, which makes them more robust and simplifies their manufacture.

[0022] Unlike in the examples mentioned above, the decoupling element 260, made of elastic material, can in principle only be used on one side of the membrane, so that it is located either between the membrane support frame 250 and the first magnet arrangement 220, or between the membrane support frame 250 and the fastening element 321 (or the second magnet arrangement 221). In this case, the membrane is only partially decoupled from the magnet arrangement 220, 221 or the fastening element 321.

[0023] Furthermore, the membrane can also have a support frame on one side, although in the drawings membrane support frames are arranged on both sides of the membrane.

[0024] The transducer according to the invention can advantageously be used as a sound transducer, e.g. in microphones, loudspeakers or headphones.

Claims

[1] Planar dynamic transducer (200) comprising a first planar magnet arrangement (220), a fastening element (221, 321) and a diaphragm (240) with conductor tracks (245) and at least one diaphragm support frame (250), wherein the diaphragm support frame is clamped between the magnet arrangement and the fastening element, wherein at least one decoupling element (260) made of elastic material is located between the membrane support frame (250) and the first magnet arrangement (220) and / or between the membrane support frame (250) and the fastening element (221, 321), wherein the first magnet arrangement (220) and the fastening element (221) are connected to each other by a screw, rivet or press connection (280), wherein the screw, rivet or press connection (230) does not pass through the membrane support frame (250), and wherein the screw, rivet or press connection (280) lies substantially in the plane of the membrane (240) or parallel to the plane of the membrane and the magnet arrangement (220) and the fastening element (221,321) have at least one overlap (270) through which the screw, rivet or press connection (280) is guided. [2] Converter according to claim 1, wherein the first magnet arrangement (220) comprises several bar magnets (210) and a frame (220a) to which the bar magnets are attached. [3] Converter according to claim 1 or 2, wherein the fastening element (221) is a second magnet arrangement which is essentially mirror-symmetric to the first magnet arrangement (220). [4] Converter according to one of claims 1 to 3, wherein the overlap (270) is designed in the form of a groove and / or tongue. [5] Converter according to one of claims 1 to 4, wherein the screw, rivet or press connection (280) is axially movable and such that the fastening element (221) and the first magnet arrangement (220) can spread apart from each other. [6] Transducer according to one of claims 1-5, wherein the decoupling element (260) is made of elastic material, a silicone adhesive, an elastic foam, an elastic adhesive film or a viscoelastic material. [7] Headphones with a planar dynamic transducer according to one of claims 1-6. [8] Microphone with a planar dynamic transducer according to one of claims 1-6.

Images