Electromagnetic signal transducer for bone conduction earphone

Abstract

The invention relates to an electromagnetic signal transducer for bone conduction headphones, comprising at least one soft magnetic armature (4) which is movable relative to a pole (1a, 1b) carrying at least one electric coil, at least one permanent magnet (9) for generating a magnetic bias of the armature (4), and at least one soft magnetic yoke (8) which, together with the at least one permanent magnet (3), the at least one pole (1a, 1b) and the at least one armature (4), forms at least one magnetic circuit, in order to keep the small non-linearity of the magnetic resistance force small, at least a first pole (1a) and a second pole (1b) are provided, which each carry at least one electric coil (2), the two poles are identical in construction and are arranged symmetrically to one another on a common pole axis (5), the at least one armature (4) is arranged between the at least two poles (1a, 1b) arranged symmetrically to one another and is movable relative to the poles (1a, 1b) along the pole axis (5), in each case forming an axial working air gap (7), the at least one permanent magnet (3) is magnetized perpendicular to the pole axis (5) and is arranged radially outside the at least one armature (4), a circumferential surface (15) of the at least one armature (4) facing the at least one permanent magnet (3) forms a radial air gap (14) through which the armature (4) is magnetically coupled to the permanent magnet (3), and the axial thickness of the permanent magnet (3) is equal to or greater than the axial spacing between the two poles (1a, 1b).

Description

Technical Field

[0001] This invention relates to an electromagnetic signal converter for bone conduction headphones, the electromagnetic signal converter comprising: - At least one soft magnetic armature, which is movable relative to a pole supporting at least one electric coil. - At least one permanent magnet for generating the magnetic bias of the armature, and - At least one soft magnetic yoke, which together with the at least one permanent magnet, the at least one pole and the at least one armature forms at least one magnetic circuit.

[0002] Electromagnetic signal converters should be installed, especially in bone conduction headphones for diagnostic equipment, but can also be installed in hearing and communication systems. Background Technology

[0003] Bone conduction headphones, as known in the prior art, convert electrical signals into mechanical vibrations and thus function as an electromagnetic signal converter and vibration generator. Furthermore, this technology is used in hearing aids and is particularly suitable for people with damage to the outer and middle ear, because in such cases sound cannot be transmitted as airborne sound to the tympanic membrane and from there to the cochlea via solid conduction through the incus and stapes. The acoustic signal to be transmitted to the person is created as an electrical signal or converted from an acoustic signal to an electrical signal, for example, by means that the electrical signal is received by a microphone. Typically, the electrical signal is amplified, processed, and transmitted to the electromagnetic signal converter. In the signal converter, the electrical signal is fed to at least one coil, which accordingly causes the armature to vibrate. The oscillator, serving as the armature, contacts the body, for example, at the skull location, where the acoustic signal, in the form of tactile vibrations, is transmitted directly to the inner ear, bypassing the middle ear, where it is converted into neural stimulation in the cochlea.

[0004] With a small air gap, i.e., the working air gap between the armature and the pole, high force density can be achieved with small electrical excitation according to the principle of magnetoresistive force. Accordingly, the force F acting on the armature is proportional to the square of the air gap induction and therefore to the square of the current supplied to the coil. This square relationship means that the frequency of the force component in the sinusoidal oscillation of the magnetic field doubles. Therefore, there is no signal fidelity mapping. Furthermore, the working air gap also changes due to vibration, further distorting the transmission characteristics.

[0005] Signal proportioning can be established under certain boundary conditions through the magnetic bias of the armature—in which a static magnetic field superimposed on a dynamic electric field is generated by one or more permanent magnets. While the solution according to EP 3065420 A1 significantly reduces reluctance and current consumption by using highly coercive permanent magnets and thus smaller magnet heights, as well as by implementing a secondary flux path for electrodynamic excitation, fundamental problems of distortion factor and armature self-adhesion remain.

[0006] The signal converter in US 2003 / 0034705 A1 also incorporates the principle of superimposing static and dynamic magnetic flux in proportional electromagnetic signal conversion, but it uses multiple working air gaps with the magnetic flux oriented in the same direction in some gaps and in opposite directions in others. Furthermore, the signal converter in US 2003 / 0034705 A1 has a different mechanical structure compared to EP3065420 A1, in which the adapter yoke, coil body, and coil are connected to each other and act as an armature, capable of vibrating relative to a unit consisting of a permanent magnet, yoke, base plate, rod, and balancing mass. Therefore, in US 2003 / 0034705 A1, there is no armature that can move relative to the coil.

[0007] Magnetic drag is generated by the magnetic flux of the permanent magnet in the direction of decreasing magnetic reluctance. In some embodiments of US2003 / 0034705 A1, this magnetic drag is compensated by spring force. In the double air gap system of Figures 4 and 5 according to US 2003 / 0034705 A1, no magnetic drag occurs in the symmetrical position of the component used as the armature. However, this operating point is unstable. Once a shift occurs, the magnetic drag also acts in the same direction as the shift and must be compensated by spring force. This magnetic drag is caused by the decrease in total magnetic reluctance during the shift, because the decrease in magnetic reluctance (increase in permeability) in the closed operating air gap is greater than the increase in resistance in the open operating air gap. Magnetic energy increases and generates force. However, this increase in magnetic drag with shift is nonlinear and can be well approximated by a cubic polynomial. The greater the shift of the operating point of the permanent magnet in the direction of increasing operating magnetic induction, the greater the magnetic drag. The implementation according to US 2003 / 0034705 A1 has a particularly strong permeability variation and therefore nonlinear magnetic reluctance, because the permanent magnet flux is not only closed as shown in US 2003 / 0034705 A1, but feeds a secondary path with higher permeability to the armature through this type of arrangement of permanent magnets and air gaps, and the armature generates electromagnetic flux by means of its coil.

[0008] In diagnostic equipment where high precision is required to minimize distortion, nonlinearity in the offset is intolerable. Inverse control using an asymptotic spring characteristic curve is necessary to compensate for this nonlinearity. This is extremely complex.

[0009] However, not only is a small distortion factor important, but also the intensity of the vibration (which requires a specific spring stiffness between the armature and the vibrating mass) and the correct resonant frequency, which is derived from the spring constant and the vibrating mass. The vibrating mass of the system needs to be as large as possible.

[0010] Since signal fidelity is the highest priority for bone conduction headphones in diagnostic technology, current consumption is secondary, as these devices are mostly grid-fed or have enough space for large batteries. Summary of the Invention

[0011] Therefore, the object of the present invention is to overcome the shortcomings of the prior art and to propose an electromagnetic signal converter, particularly, but not only for diagnostic purposes, which causes a small shift in the operating point (change in permeability) on the permanent magnet when the armature is deflected, so as to keep the magnetic reluctance and thus the nonlinearity of the magnetic reluctance small.

[0012] This task is solved by an electromagnetic signal converter. The starting point of this invention is an electromagnetic signal converter for bone conduction headphones, the electromagnetic signal converter comprising: - At least one soft magnetic armature, which is movable relative to a pole supporting at least one electric coil. - At least one permanent magnet for generating the magnetic bias of the armature, and - At least one soft magnetic yoke, which together with the at least one permanent magnet, the at least one pole and the at least one armature forms at least one magnetic circuit.

[0013] In this provision, - It is provided with at least a first pole and a second pole, each of which supports at least one electric coil. The two poles have the same structure and are arranged symmetrically to each other on a common pole axis. - At least one armature is disposed between at least two poles arranged symmetrically to each other, forming an axial working air gap, and is movable relative to the poles along the pole axis. - The at least one permanent magnet is magnetized perpendicular to the polar axis and is disposed outside the radial direction of the at least one armature. - A radial air gap is formed on the circumferential surface of the at least one armature facing the at least one permanent magnet, through which the armature is magnetically coupled to the permanent magnet, and the axial thickness of the permanent magnet is equal to or greater than the axial distance between the two poles.

[0014] In this way, the axial thickness of the permanent magnet is always greater than the axial thickness of the armature between the poles, so that when the armature moves along the pole axis, at least the portion of the armature located between the poles, usually the majority of the armature, always overlaps with the permanent magnet in the axial direction. Through the resulting extension of the permanent magnet relative to the armature and the magnetic field extending through the permanent magnet's movement, which is now perpendicular to the pole axis and therefore transverse to the armature, the armature experiences smaller flux fluctuations during its movement, resulting in a smaller shift in the operating point on the permanent magnet, and thus reducing magnetic reluctance and, consequently, its nonlinearity.

[0015] The axial overlap of the armature and permanent magnet generates a centering force on the armature based on the width of the radial air gap and the maximum offset of the armature. This centering force reacts to and at least partially compensates for the magnetic reluctance. The width of the radial air gap remains constant even as the armature moves relative to one or more permanent magnets.

[0016] This ensures high constantness of the magnetic flux of the permanent magnet, i.e., a small offset correlation between the magnetic field of the permanent magnet and the armature. Simultaneously, the structure of the signal converter according to the invention exhibits low magnetoresistance in the flux path of electromagnetic excitation, resulting in a high force / current constant.

[0017] Regarding the terminology used: "radial air gap" has a length along the polar axis, corresponding to the maximum extension of the air gap surface, and a width resulting from the distance between the circumferential surface of the armature and the adjacent permanent magnet, more precisely, its pole face, which is measured in the radial direction relative to the polar axis. The term "thickness (or height)" refers to the axial thickness (or axial height), i.e., the thickness (or height) measured in the direction of the polar axis, and "axial spacing" refers to the spacing measured in the direction of the polar axis. The axial thickness of the permanent magnet in relation to the structure of the signal converter is usually—with regard to the permanent magnet—called the width of the permanent magnet, because the length and width of the permanent magnet form its pole face, and as thickness usually—again, with regard to the permanent magnet—actually refers to the magnet height, which is measured in the direction of magnetization.

[0018] The pole face facing the armature has a surface normal (= pole axis), which points in the dimensional direction of the working air gap width and is therefore located in the direction of motion.

[0019] The armature has at least two parallel pole faces and at least one circumferential surface that generally extends perpendicular to the pole faces of the armature. The inwardly facing pole face of the permanent magnet is opposite to the circumferential surface of the armature and forms a radial air gap.

[0020] The circumferential surface of the armature typically extends parallel to the polar axis in a longitudinal sectional view, i.e., a sectional view parallel to the polar axis. Similarly, the pole face of the permanent magnet, adjacent to the circumferential surface of the armature and forming a radial air gap with it, extends parallel to the polar axis and therefore parallel to the circumferential surface of the armature. Thus, the radial air gap between the circumferential surface of the armature and the pole face of the permanent magnet has a constant width along the polar axis.

[0021] The magnetic flux generated by (multiple) permanent magnets passes through the armature, the working air gap between the armature and one pole, the pole, and closes through the soft magnetic yoke in the first magnetic circuit. The second magnetic circuit passes through the armature, the working air gap between the armature and another pole, the other pole, and closes through the soft magnetic yoke.

[0022] The armature is constructed symmetrically about a plane perpendicular to the polar axis. The permanent magnet is also constructed symmetrically about this plane. In the stationary state of the armature—where no movement is induced by the coil—the armature is held in such a way by a suspension device that the first and second working air gaps are of the same size.

[0023] The signal converter according to the invention, in its very simple form, has an armature surrounded by one or more permanent magnets.

[0024] An armature is positioned between two identical, symmetrically arranged poles. A soft magnetic yoke closes the two magnetic circuits. The armature, poles, and permanent magnet can be constructed with rotational symmetry about the pole axis. In this case, the permanent magnet will be toroidal or will form a toroidal ring together.

[0025] The armature can also be rectangular (viewed along the polar axis). In this case, permanent magnets, such as bar magnets, are provided on at least two parallel sides of the armature, especially on the wider side, more precisely, parallel to each other in a plane perpendicular to the polar axis, so that the radial air gap between the armature and each permanent magnet is always the same size. In this case, the bar magnet is at least as long as the corresponding side of the rectangle. Preferably, a unique bar magnet is used on each side. As a special case of a rectangular armature, a square armature can also be conceived. Thus, while maintaining a constant radial gap, either a bar magnet is provided on each side of the cube, preferably one bar magnet on each side of the cube, which is at least as long as one side of the square armature, or again, only two parallel sides of the cube are provided with bar magnets, preferably one bar magnet on each side of the cube, which is at least as long as one side of the square armature. In summary, the armature can have a regular n-gon shape, surrounded by n bar magnets with a constant radial gap, the bar magnets corresponding to the side lengths of the n-gon. The poles and coils are typically constructed rotationally symmetrically about the pole axis, independent of the shape of the armature.

[0026] The poles used for the armature can consist of multiple sub-poles (Teilpoles) each with its own coil; for example, instead of a single pole, four sub-poles can be provided, covering the rectangular armature. It is also conceivable to divide the armature into multiple sub-armatures (Teilankers). The coil of a single pole can be composed of multiple, especially identical, sub-coils (Teilspule).

[0027] However, the signal converter according to the present invention may also include multiple units, each consisting of an armature, two poles, a permanent magnet surrounding an arrangement, and a soft magnetic yoke. These units may be arranged sequentially along a common polar axis, and / or these units may be arranged side-by-side along their own polar axes.

[0028] To obtain the largest possible vibrational mass, it is preferably specified that the at least one armature is a fixed part of the signal converter, in particular fixedly connected to the housing surrounding the magnetic circuit, while the at least two poles, the at least two coils, the at least one permanent magnet and the at least one soft yoke are fixedly connected to each other and form the vibrational mass of the signal converter relative to the armature.

[0029] The signal converter according to the invention thus has, in its extremely simple form, an armature fixedly connected to a housing and a vibrating mass comprising two poles, coils of the poles, one or more permanent magnets surrounding the armature, and a soft magnetic yoke.

[0030] Only the armature, such as an armature plate, is fixedly connected to the housing, through which vibrations are transmitted to the human body. All other active components, such as permanent magnets, soft yokes, and even the poles of coils, are vibrating masses that vibrate relative to the armature and housing. This maximizes the vibrating mass.

[0031] If the signal converter according to the present invention comprises multiple units, each of which consists of an armature, two poles, a permanent magnet surrounding an arrangement, and a soft magnetic yoke, then on the one hand, the armatures are connected to each other or all the armatures are connected to a housing, and on the other hand, the vibrating masses are connected to each other to form a common vibrating mass.

[0032] To further increase the vibratory mass, it may be specified that the vibratory mass includes at least one additional mass that is less magnetized than the pole, armature, or soft yoke. The additional mass should not function in the magnetic circuit, and thus it should not be magnetized or should be at least less magnetized than the magnetizable elements of the magnetic circuit.

[0033] Typically, the fixed part of the signal transducer is connected to the vibrating mass of the transducer via an elastic element. The elastic element holds the armature between the two poles in a stationary state such that the first and second working air gaps are of the same size. Preferably, the armature is elastically connected to the vibrating mass via at least one spring, particularly a leaf spring. It is preferable to have one spring on each side outside the axial direction of the soft magnetic yoke, thus providing a total of two springs. The armature is suspended on these springs, and the resonant frequency of the vibration system is determined by the spring constants of the springs and the vibrating mass.

[0034] When the maximum radial extension of the armature measured in relation to the pole axis is greater than the maximum radial extension of the pole measured in relation to the pole axis, the nonlinearity of the magnetic reluctance is reduced in a favorable manner. In particular, the maximum radial extension of the armature measured in relation to the pole axis can be greater than the maximum radial extension of the pole end face, i.e., the pole face facing the armature.

[0035] In one embodiment of the invention, the armature is configured as a plate shape, at least in the region radially within the poles. "Plate shape" means that the end faces are flat and parallel to each other, and the distance between the end faces, i.e., the axial height or thickness of the armature, is less than its radial extension dimension. When the armature protrudes radially beyond the poles, it may also have the same height as between the poles in that region. In this case, the armature will be entirely plate-shaped. The plate shape of the armature results in a flattened structure for the signal transducer.

[0036] In one embodiment of the invention, the axial thickness of the armature is specified to widen outward from the radial direction of the pole toward the circumferential surface of the armature. This improves the magnetic coupling with the one or more permanent magnets and reduces the nonlinearity of the reset force. This widening occurs symmetrically in both directions of the pole axis.

[0037] In one embodiment of the invention, the pole is plate-shaped and has a notch for a coil, which is mounted within the plate thickness. In this case, the pole has a core supporting the coil and a plate or pole shoe that does not support the coil and faces the armature. "Plate-shaped" here also means that the end faces of the pole (also called pole faces) are flat and parallel to each other, and the distance between said end faces, i.e., the axial thickness of the pole, is less than its maximum radial extension dimension. The plate shape of the yoke facilitates a low structural height for the signal converter.

[0038] In one embodiment of the invention, a soft magnetic yoke is provided, for each pole, a plate-shaped cover and at least one wall. The cover abuts against the pole in the axial direction and covers the pole in the radial direction. The wall is connected to the cover and surrounds the pole with the coil, the armature, and the at least one permanent magnet in the radial direction, and the at least one permanent magnet is fixed to the wall. Thus, there are two covers and at least one common wall connecting the two covers to each other. The wall is provided, especially at least where the permanent magnet is located, in the circumferential direction around the pole axis. In particular, the permanent magnet is located on the wall or is radially fully or partially recessed into the wall. If, for example, a rectangular armature is present, the armature has the permanent magnet only on the wide side of the rectangle, so that only one wall is provided on each wide side of the armature. In this case, the two covers and the two walls will have the shape of a quadrature shell.

[0039] Alternatively, one could conceive of setting up a closed, surrounding wall along the circumferential direction around the polar axis. In this way, the armature and magnetic poles would be at least completely surrounded by a soft magnetic material. In this case, the two caps and the surrounding wall would, for example, have the shape of a hollow cylinder or a hollow cuboid.

[0040] To ensure the permanent magnet is connected to the at least one magnetic circuit and to keep the structural space small in the radial direction, it can be specified that the at least one permanent magnet is internally disposed in a recess in the wall. In particular, the at least one permanent magnet is flush-attached to the surface of the wall or the recess. Attached Figure Description

[0041] The invention will now be further illustrated with reference to embodiments. The accompanying drawings are exemplary and intended to illustrate the ideas of the invention, but are described in a limiting or even closed manner. The drawings are as follows: Figure 1 A longitudinal cross-sectional view of a signal converter according to the invention, schematically shown in a first embodiment, is illustrated. Figure 2 A longitudinal cross-sectional view of a signal converter according to the invention, schematically illustrated in a second embodiment, is shown. Figure 3 A longitudinal cross-sectional view of a signal converter according to the invention, shown schematically in a third embodiment, is presented. Detailed Implementation

[0042] Figure 1The signal converter mainly includes two identical poles 1a and 1b, two permanent magnets 3 in the form of cuboid magnets, and a plate-shaped armature 4. Each pole has an electric coil 2, and the longitudinal direction of the cuboid magnets is perpendicular to the plane of the figure. The poles 1a and 1b and the coils 2 are configured to be rotationally symmetrical about the pole axis 5. The armature 4 is not configured to be rotationally symmetrical about the pole axis 5, but is configured as a rectangle. Each pole 1a and 1b approaches the armature 4 with its pole face 6 up to the working air gap 7 for the armature 4. The poles 1a and 1b are plate-shaped and have trapezoidal notches in cross-section for the coils 2 on their end faces away from the armature 4. Of course, the poles 1a and 1b and the coils 2 can also be configured differently.

[0043] exist Figure 1 The radial length of the armature 4 is greater than the radial lengths of poles 1a and 1b. The permanent magnet 3 is positioned radially at the same spacing as the pole axis 5 and is thicker or taller than the armature 4—measured in the direction of the pole axis 5. The armature 4 is entirely plate-shaped. The permanent magnet 3 is positioned radially outside the armature 4 about the pole axis 5 and forms a radial air gap 14 with the circumferential surface 15 of the armature (which is composed of four rectangles). The armature 4 is magnetically coupled to the permanent magnet 3 through this radial air gap. The air gap 14 has a constant width at the height of the circumferential surface 15 of the armature 4, and more precisely, not only in the state where no electrical signal is applied to the coil 2, but also in the state where an electrical signal is applied to the coil 2 and the armature 4 is offset from its rest position.

[0044] To close the two magnetic circuits, a soft magnetic yoke 8 is provided, which comprises two identical U-shaped or bridge-shaped components and is essentially constructed as a cuboid shell. In other words, the soft magnetic yoke 8 consists of two plate-shaped covers 9 and two flat walls 10 (in... Figure 1 The yoke 8 (shown on the left and right sides) consists of a cover that abuts against poles 1a and 1b axially and also against the coil 2 of the poles, and covers poles 1a and 1b radially. The wall connects to the two covers 9 and surrounds the poles 1a and 1b with coil 2, the armature 4, and the permanent magnet 3. In this example, no wall 10 (and no permanent magnet 3) is provided parallel to the plane of the drawing; that is, the yoke 8 is open. However, it is conceivable that two walls 10 (with or without permanent magnet 3) are also provided parallel to the plane of the drawing, so that the yoke 8 as a whole has a hollow cuboid shape.

[0045] The wall 10 has a recess inside, and the permanent magnet 3 is fixed in the recess at least with its outer pole surface.

[0046] The soft magnetic yoke 8 can also be constructed in other ways as a two-piece unit, for example, in which a lid 9 and a wall 10 form a can-shaped component, and then another lid 9 is placed on the component.

[0047] The permanent magnet 3 is magnetized perpendicular to the pole axis 5 and is constructed, for example, as an Sm2Co17 or NdFeB magnet. The poles 1a and 1b can be made of soft magnetic metal. The armature 4 and the soft magnetic yoke 8 can be made of the same material as the poles 1a and 1b.

[0048] The housing, not shown here, encloses all the mentioned and shown components of the signal converter, protects it from environmental influences, and can be placed on the body of the patient to be examined. The armature 4 is fixedly connected to the housing and elastically connected to the vibrating mass of the signal converter, allowing the armature to move freely relative to the vibrating mass, i.e., relative to the poles 1a and 1b with coils 2, the permanent magnet 3, and the soft yoke 8, more precisely, along the pole axis 5. The poles 1a and 1b, coils 2, permanent magnet 3, and soft yoke 8 are fixedly connected to each other and together form the vibrating mass. Of course, an additional mass 16 can also be provided on the vibrating mass, as in... Figure 3 As shown in the image.

[0049] Armature 4 is elastically connected to the vibrating mass via two leaf springs 17, which in Figure 1 Not shown in the image, but can be found from... Figure 3 As can be seen, the two working air gaps 7 are adjusted by the preload of the leaf spring 17. The magnetic flux electrically excited by the coil 2 is superimposed on the magnetic flux of the permanent magnet, which has opposite directions in the two working air gaps 7. The magnetic flux travels, for example, from the armature 4 to the pole faces 6 of poles 1a and 1b. The electrically excited magnetic flux extends from top to bottom or in the opposite direction along the pole axis 5. Therefore, it reduces the magnetic flux in one working air gap 7 and increases the magnetic flux in the other working air gap 7. This results in different forces on both sides and the armature 4 moves in such a way that the armature reduces the working air gap 7 by means of the stronger magnetic flux. The movement of the armature 4 is transmitted to the human body through a housing (not shown).

[0050] according to Figure 2 signal converter and Figure 1 The signal converters in them are very similar, therefore regarding Figure 1 The content described applies and therefore only illustrates the differences. Coil 2 in Figure 2 The middle part is located in a rectangular notch in the cross-section of poles 1a and 1b. However... Figure 1 and 2 The notches used for coil 2 are interchangeable.

[0051] Armature 4 Figure 2The armature 4 is plate-shaped only between poles 1a and 1b. Outside poles 1a and 1b, the axial height or thickness of the armature 4 is symmetrically widened in both directions of the pole axis 5, more specifically, by approximately one-quarter of the height or thickness of the armature 4 between poles 1a and 1b. The height of the circumferential surface 15 is preferably greater than the axial distance between the pole faces of the two poles 1a and 1b. However, the height of the circumferential surface 15 is preferably less than the axial thickness of the permanent magnet 3, more specifically, less than the axial dimension of the pole face of the permanent magnet 3 oriented towards the armature 4. Figure 1 and Figure 2 The shape of armature 4 in the middle is interchangeable.

[0052] Holes 12 are concentrically arranged around the pole axis 5, passing through poles 1a and 1b, the soft magnetic yoke 8, and the armature 4 itself, to secure the armature 4 to a housing (not shown), for example, by tightening. Additionally, several smaller holes 13 are provided to tighten the soft magnetic yoke 8 to poles 1a and 1b. Of course, the soft magnetic yoke 8 can also be connected to each pole 1a and 1b in other ways, such as by bonding. The corresponding holes 12 and / or smaller holes 13 (or bonding instead of holes 13) are for tightening according to… Figure 1 The implementation method is also necessary.

[0053] A total of four threads 11 are shown in the cover 9 of the soft magnetic yoke 8, which can also be set according to... Figure 1 and 3 In the implementation method, these threads are used to tighten and preload the leaf spring 17 by means of screw 19, see [link to implementation details]. Figure 3 .

[0054] Figure 3 The implementation method is similar to that based on Figure 1 The implementation method is described herein, therefore only the method described here is related to... Figure 1 Different distinctions or characteristics. Figure 3 The diagram illustrates how the stationary and vibrating parts of the signal converter can be interconnected using a leaf spring 17. This can also be configured according to... Figure 1 and 2 In the implementation method.

[0055] Free spaces are provided in the yoke 8, poles 1a and 1b, and armature 4 to establish the connection between armature 4 and leaf spring 17. These free spaces are provided through... Figure 2 The central hole 12 and through Figure 3 The two corresponding holes next to the polar shaft 5 are used to achieve this. Figure 3A threaded pin 20 and two threaded sleeves 22 are inserted into these holes, respectively. The threaded pins extend through the entire arrangement and thus through the armature 4, and the threaded sleeves 22 extend through the cover 9 and a pole 1a, 1b, respectively. The leaf spring 17 is fitted onto the threaded pin 20 and secured by a nut 21. In this case, the threaded pin 20 also serves to connect the armature 4 to the housing. Of course, the connection between the armature 4 and the leaf spring 17 can also be achieved in other ways.

[0056] Yoke 8 and poles 1a and 1b in Figure 3 In-middle bonding, thereby eliminating the need for bonding as described in the original text. Figure 2 Hole 13 is provided in the embodiment.

[0057] Additional mass 16 in accordance with Figure 3 In the embodiment, the poles 1a and 1b are arranged radially between the wall 10 of the soft magnetic yoke 8 and the poles 1a and 1b, and axially between the permanent magnet 3 and the cover 9 of the soft magnetic yoke 8. According to... Figure 1 and 2 In some implementations, an additional mass 16 can also be provided, for example, in conjunction with... Figure 3 In the corresponding position.

[0058] Physical signal transducers are used in hearing and communication systems, as well as for hearing diagnosis, and are worn and used on the skull of humans or animals in bone conduction headphones (hearing aids). The dimensions of the bone conduction headphones and therefore the signal transducer are determined according to the application. In some implementation variations of the physical signal transducer, the transducer is very small, with a height of approximately 8-10 mm measured externally along axis 5 from cover 9 to cover 9. The diameter of the soft magnetic element, i.e., measured from the outer side of wall 10 to the outer side of the opposite wall 10, is 15-25 mm, for example, 20 mm. The permanent magnet 3 has an axial height of, for example, 2-5 mm, for example, 3 mm, and a radial dimension of 1-2 mm, for example, 1.5 mm.

[0059] List of reference numerals

[0060] 1a, 1b poles

[0061] 2 coils

[0062] 3 permanent magnets

[0063] 4. Armature

[0064] 5 Polar axis

[0065] 6. Polar surfaces of poles 1a and 1b

[0066] 7. Working air gap

[0067] 8. Soft magnetic yoke

[0068] 9. Cover

[0069] 10 walls

[0070] 11 Thread

[0071] 12 holes

[0072] 13 holes

[0073] 14 Air gap

[0074] 15. Peripheral surface of armature 4

[0075] 16. Added mass

[0076] 17 Leaf Springs

[0077] 18 Spacer retainers

[0078] 19 Screws

[0079] 20 threaded pins

[0080] 21 Nuts

[0081] 22 Threaded sleeve

Claims

1. An electromagnetic signal converter for bone conduction headphones, the electromagnetic signal converter comprising: - At least one soft magnetic armature (4), which is movable relative to the poles (1a, 1b) supporting at least one electric coil, - At least one permanent magnet (3) for generating the magnetic bias of the armature (4), and - At least one soft magnetic yoke (8), the soft magnetic yoke, together with the at least one permanent magnet (3), the at least one pole (1a, 1b) and the at least one armature (4), forms at least one magnetic circuit, characterized in that, - It is provided with at least a first pole and a second pole, the first pole and the second pole respectively supporting at least one electric coil (2), the two poles have the same structure and are arranged symmetrically to each other on a common pole axis (5). - At least one armature (4) is disposed between at least two poles (1a, 1b) arranged symmetrically to each other, forming an axial working air gap (7) respectively, and is movable relative to the poles (1a, 1b) along the pole axis (5). - The at least one permanent magnet (3) is magnetized perpendicular to the polar axis (5) and is disposed radially outside the at least one armature (4). - A radial air gap (14) is formed on the circumferential surface (15) of the at least one armature (4) facing the at least one permanent magnet (3), through which the armature (4) is magnetically coupled to the permanent magnet (3), and the axial thickness of the permanent magnet (3) is equal to or greater than the axial distance between the two poles (1a, 1b).

2. The signal converter according to claim 1, characterized in that, The at least one armature (4) is a fixed part of the signal converter, and the at least two poles (1a, 1b), at least two coils (2), at least one permanent magnet (3) and at least one soft magnetic yoke (8) are fixedly connected to each other and form the mass of the signal converter that vibrates relative to the armature (4).

3. The signal converter according to claim 2, characterized in that, The at least one armature (4) is fixedly connected to the housing surrounding the magnetic circuit.

4. The signal converter according to claim 2, characterized in that, The mass of the vibration includes at least one additional mass that can be magnetized less than the poles (1a, 1b), armature (4), or soft yoke (8).

5. The signal converter according to any one of claims 2 to 4, characterized in that, The armature is elastically connected to the vibrating mass via at least one spring.

6. The signal converter according to claim 5, characterized in that, The spring is a leaf spring (17).

7. The signal converter according to any one of claims 1 to 4, characterized in that, The maximum extension dimension of the armature (4) measured radially to the polar axis (5) is greater than the maximum extension dimension of the poles (1a, 1b) measured radially to the polar axis (5).

8. The signal converter according to any one of claims 1 to 4, characterized in that, The armature (4) is constructed in a plate shape in at least the region within the radial direction of the poles (1a, 1b).

9. The signal converter according to any one of claims 1 to 4, characterized in that, The axial thickness of the armature (4) is widened in the radial direction of the poles (1a, 1b) toward the circumferential surface (15) of the armature (4).

10. The signal converter according to any one of claims 1 to 4, characterized in that, The poles (1a, 1b) are plate-shaped and have notches for coils (2), which are mounted within the thickness of the plate.

11. The signal converter according to any one of claims 1 to 4, characterized in that, The soft magnetic yoke (8) has a plate-shaped cover (9) and at least one wall (10) for each pole (1a, 1b), the cover abutting against the pole (1a, 1b) in the axial direction and covering the pole in the radial direction, the wall being connected to the cover (9), the wall surrounding the pole (1a, 1b) with coil (2), armature (4) and at least one permanent magnet (3) in the radial direction, and the at least one permanent magnet (3) being fixed to the wall.

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