Impulse generator, especially for a sound transducer

Abstract

Impulse generator (1; 101; 201; 301), especially for a sound transducer, with the following features: - a ferromagnetic yoke (10; 110; 210), wherein the yoke (10; 110; 210) has a yoke gap (15; 115; 215) which is formed around a longitudinal axis (L), - a permanent magnet (30) that forms a magnetic field (40), and - a currentable coil (50; 350), wherein the coil (50; 350) is arranged to be movable along the longitudinal axis (L), - wherein the yoke (10; 110; 210) with the yoke gap (15; 115; 215) guides the magnetic field (40) of the permanent magnet (30), wherein the magnetic field (40) comprises a yoke gap main field (41) inside the yoke gap (15; 115; 215) and a yoke gap stray field (42) outside the yoke gap (15; 115; 215), and - wherein the coil (50; 350) is arranged along the longitudinal axis (L) at a distance from the yoke gap (15; 115; 215) such that the yoke gap stray field (42) passes through the coil (50; 350) so that a force acts on the coil (50; 350) which is supplied with a variable current.

Description

[0001] The invention relates to a pulse generator for a sound transducer, having the features of claim 1, and a sound transducer having the features of claim 16.

[0002] Pulse generators are used to convert an electrical signal into a mechanical signal. This is achieved by setting a coil located in a magnetic field into oscillation by applying an alternating signal. Typically, a permanent magnet is used to generate the magnetic field, which is guided by a yoke with a yoke gap. To achieve the highest possible efficiency, the coils in conventional pulse generators are placed within the yoke gap, as the magnetic field is strongest there.

[0003] Sound transducers whose pulse generators have a coil within the yoke gap are known from DE 10 2010 028 442 A1 and DE 10 2007 040 617 A1.

[0004] The following are cited as state of the art: DE 60 2004 013 407 T2, JP 2005 - 223 720 A, CN 1 886 005 A, US 2006 / 0 056 651 A1 and DE 10 2015 222 400 A1.

[0005] A disadvantage of such pulse generators is that the ingress of moisture, dust, dirt, and other particles within the yoke gap must be prevented to avoid impeding the coil's oscillation. Furthermore, the precise positioning and winding of the coil within the yoke gap during assembly are challenging and time-consuming.

[0006] The present invention is dedicated to the task of proposing a generic impulse generator, in particular for a sound transducer, which expediently eliminates the disadvantages known from the prior art.

[0007] These tasks are solved by a pulse generator, in particular for a sound transducer with the features of claim 1 and a sound transducer according to the features of claim 16.

[0008] Advantageous embodiments and further developments of the invention are specified in the dependent claims.

[0009] According to the invention, a pulse generator, particularly for a sound transducer, comprises a ferromagnetic yoke, the yoke having a yoke gap extending around a longitudinal axis. The pulse generator includes a permanent magnet generating a magnetic field and a current-carrying coil, the coil being movably arranged along the longitudinal axis. The yoke with the yoke gap guides the magnetic field of the permanent magnet, the magnetic field comprising a main yoke gap field within the yoke gap and a stray yoke gap field outside the yoke gap. The stray yoke gap field is preferably located near the yoke gap. According to the invention, the coil is arranged along the longitudinal axis at a distance from the yoke gap such that the stray yoke gap field passes through the coil, thereby exerting a force, particularly in a common direction, on the coil when it is energized with a variable current.

[0010] In connection with this invention, the magnetic field in the region of the yoke gap comprises the yoke gap main field and the yoke gap stray field. The yoke gap main field is formed within the yoke gap, with its magnetic field lines passing perpendicularly or nearly perpendicularly through the yoke gap.

[0011] Furthermore, in connection with this invention, the yoke gap stray field is defined as the magnetic field that forms outside the yoke gap. The yoke gap stray field forms immediately adjacent to the yoke gap. The magnetic field lines of the yoke gap stray field preferably have an arc-shaped profile, whereby the field lines of the yoke gap stray field exhibit a vector component in the direction of the longitudinal axis of the yoke gap.

[0012] The present invention is based on the idea of ​​providing a pulse generator whose coil is arranged along the longitudinal axis not in the yoke gap, but rather at a distance close to the yoke gap. This arrangement takes advantage of the fact that the stray field passing through the coil is large enough to cause the coil to vibrate when a variable current signal is applied to it, thus eliminating the need to keep the yoke gap free of dirt and moisture, especially in harsh applications.

[0013] Furthermore, by cleverly shaping the yoke, the yoke gap stray field can be deflected in such a way that the intensity of the magnetic field passing through the coil is increased.

[0014] Furthermore, the coil can be arranged within a support element, for example, a glass pane. Excitation of the coil causes the support element, in the previous example the glass pane, to vibrate and generates a sound pressure that is perceived as an acoustic signal.

[0015] Such training for the impulse generator is extremely compact and cost-effective.

[0016] Advantageously, the coil is arranged to be movable along its longitudinal axis, preferably in a linear manner. The linear motion makes the suspension or mounting of the coil very simple.

[0017] Preferably, the longitudinal axis of the yoke gap and a central axis of the pulse generator run coaxially to each other.

[0018] According to an advantageous embodiment of the invention, the yoke gap is annular, preferably symmetrical about its longitudinal axis. Due to the symmetrical design of the yoke gap along its longitudinal axis, the yoke gap stray field also forms along this longitudinal axis. A coil, preferably arranged symmetrically about the longitudinal axis of the yoke gap and located within the symmetrical yoke gap stray field, experiences a force exclusively along the longitudinal axis of the yoke gap, thereby improving sound emission.

[0019] According to a particularly preferred embodiment of the invention, the yoke gap has a width, wherein the yoke gap exhibits a different width at least in certain sections. For example, the width of the yoke gap can decrease continuously or in steps. The width of the yoke gap can also increase in the middle of the yoke gap. By skillfully adjusting the width of the yoke gap, the yoke gap leakage field can be deflected towards the coil. The larger the magnetic yoke gap leakage field passing through the coil, the greater the force acting on the coil in the longitudinal direction.

[0020] Preferably, the width of the yoke gap is greatest on the side facing the coil. This ensures that the yoke gap leakage field forms earlier and more strongly in an arc towards the coil. As a result, the coil can arrange more windings in a plane that the yoke gap leakage field penetrates.

[0021] Preferably, the coil is arranged at a distance along its longitudinal axis from the yoke gap, the distance being less than the width of the yoke gap. The distance between the coil and the yoke gap can be at least as large as the maximum oscillation amplitude of the coil. The distance between the coil and the yoke gap is greater than zero. The distance between the coil and the yoke gap can be at least 10% greater than the width of the yoke gap. The distance between the coil and the yoke gap can be at least 1.5 cm.

[0022] According to an advantageous embodiment of the invention, the yoke gap has a conical, trapezoidal, or longitudinal section. Due to the conical, trapezoidal, or trapezoidal longitudinal section of the yoke gap, the yoke gap leakage field is formed symmetrically in the direction of the coil. This arrangement results in a more curved and arc-shaped yoke gap leakage field, thus increasing the magnetic yoke gap leakage field in the region of the coil.

[0023] According to a particularly preferred embodiment of the invention, the yoke has two yoke slots arranged at equal intervals from a central axis of the pulse generator, with the permanent magnet positioned between the yoke slots and symmetrically to the central axis of the pulse generator. The two yoke slots allow for a greater force to be applied to the coil. Furthermore, a coil typically has a positive conductor and a negative conductor. To achieve optimal utilization, it is recommended to integrate both the positive and negative conductors into the force process. To achieve the flattest possible arrangement, the positive and negative conductors are arranged in the same plane.

[0024] According to a particularly preferred embodiment of the invention, the yoke gap is arranged in an annular shape and equidistant from the central axis of the pulse generator, so that the longitudinal axis and the central axis are coaxial. The coil windings are arranged circularly around the central axis of the pulse generator. The annular yoke gap and the circular coil are arranged almost parallel to each other. The circular arrangement of the pulse generator allows for a simple design of the coil winding. Furthermore, almost the entire coil is integrated into the force process.

[0025] Advantageously, the yoke gap is filled exclusively with air. Air has a significantly lower permittivity than the ferromagnetic material of the yoke. The yoke gap exhibits a considerably higher magnetic resistance than the area within the yoke, resulting in more magnetic field lines being deflected in the yoke gap region, thus increasing the intensity of the yoke gap leakage field in the coil area. Furthermore, in the yoke gap region, particularly at its edges, the magnetic field exits at an angle, due in part to the differing permittivities of air and the ferromagnetic material of the yoke. This, among other factors, gives the magnetic yoke gap leakage field an arc-shaped appearance.

[0026] According to a particularly preferred embodiment of the invention, an insulating solid material with a permittivity of less than or equal to 8 is arranged within the yoke gap. By arranging an insulating solid material within the yoke gap, the ingress of dirt and moisture into the interior of the yoke is no longer possible. This protects the permanent magnet located within the yoke from environmental influences. The insulating solid material can also have a conical or tapered and / or stepped longitudinal section.

[0027] Preferably, the yoke, in particular the yoke gap, is arranged directly on a support element, preferably a body made of plastic or glass, wherein the coil is formed within this support element and is penetrated by the yoke gap stray field. The plastic or glass body can be a component of a vehicle, in particular an automobile. The coil can be encapsulated or bonded within the plastic or glass body.

[0028] An elastic, resilient connection is required between the coil and the permanent magnet or yoke. Preferably, the coil is therefore connected to the permanent magnet or yoke by means of an elastic elastomeric adhesive or a double-sided adhesive elastomeric ring spacer. Both the elastomeric adhesive and the double-sided adhesive elastomeric ring spacer are characterized by their high elasticity and good adhesion. This elastic property of the mounting means that the coil is mounted in a way that allows it to oscillate.

[0029] Furthermore, it is advantageous that the suspension and damping elements, often the surround and spider in transducers, are eliminated, since the coil is integrated directly into a structure and the remaining yoke with permanent magnet only needs to be attached to the structure to be excited, for example, a glass plate or a plastic body. This allows for extremely flat designs of just a few centimeters, especially less than or equal to 20 mm, although these depend largely on the thickness of the permanent magnet. Additionally, a reserve in the pulse generator for the coil's excursion is no longer necessary.

[0030] According to an advantageous embodiment of the invention, the coil is designed as a helical coil. Helical coils are characterized by their compact design and simple construction and are inexpensive to produce.

[0031] Advantageously, the coil is arranged in a plane perpendicular to the longitudinal axis. This arrangement allows the pulse generator to be designed extremely compactly along the longitudinal axis. Furthermore, the yoke gap stray field decreases with increasing distance from the yoke gap in the direction of the longitudinal axis. If the windings are arranged in several planes along the longitudinal axis, the yoke gap stray field is strongest in the winding located in the plane closest to the yoke gap, while the more distant windings exhibit a weaker field.

[0032] According to a particularly advantageous embodiment of the invention, the helical coil is arranged in several planes transverse to the longitudinal axis. By dividing the windings into several planes along the longitudinal axis, the pulse generator can be designed more compactly perpendicular to the longitudinal axis.

[0033] According to a preferred embodiment of the invention, the coil is formed on a carrier element, preferably on a multilayer circuit board. The individual windings of the helical coil are printed or etched onto the individual layers of the circuit board. This allows the pulse generator to be used without directly encapsulating or mounting the coil on a fixed structure, which significantly expands the application area and purpose. The individual layers of the helical coil are electrically connected to each other via vias.

[0034] Advantageously, the support element, in particular the circuit board, or the body made of plastic or glass in which the coil is arranged, is arranged on an end face of the yoke, with the yoke gap being formed on this end face.

[0035] Preferably, the yoke gap and the coil have a width such that the width of the yoke gap and the coil extend perpendicular to the longitudinal axis of the yoke gap, and the width of the coil is longer than the width of the yoke gap. The arc-shaped path of the yoke gap leakage field takes advantage of the fact that more windings of a coil are penetrated by the yoke gap leakage field.

[0036] In a particularly advantageous embodiment of the invention, the coil winding is configured as a chaotic winding. In a chaotic winding, the coil winding is wound in an unstructured manner around one axis, preferably the longitudinal axis of the pulse generator. Chaotic windings have the advantage that they can be manufactured quickly and with simple machinery. Particularly in applications such as glass panes, a structured winding is not possible or only partially feasible, which is why a chaotic winding is a suitable option in these cases. Chaotic windings are used in loudspeaker systems, among other things, to reduce capacitive effects or to avoid certain resonances.

[0037] Preferably, the pulse generator can have two or more independently controllable coils. The coils can be arranged in one or more planes. The coils can also have different diameters. The coils can be arranged coaxially around one axis, in particular the longitudinal axis of the pulse generator, or around two different axes.

[0038] The coils, and in particular the windings of the coils, are arranged such that a symmetrical force acts on the coil along the longitudinal axis of the pulse generator, causing the coil to oscillate. In particular, the winding of the coil must be designed and arranged in such a way that the force exerted by the coil sections does not cancel each other out.

[0039] In a further advantageous embodiment of the invention, the winding direction, and thus the current direction, of the coil turns in the outer radius is reversed compared to the inner turns, preferably at the center of the coil, so that a Lorentz force acting in the same direction acts on all turns. This allows the relationship between current direction and field line direction to be the same for all turns. Preferably, the center of the coil corresponds to the center of the yoke gap.

[0040] For example, it can be advantageous if the coil has an inner section and an outer section, and if the winding direction of the inner and outer sections is reversed around the longitudinal axis. The center of the coil, which preferably has no turn, is located between the inner and outer sections. Preferably, the axis around which the coil is arranged and the longitudinal axis of the pulse generator can be spaced apart from each other. This means the coil is no longer arranged symmetrically around the air gap, and preferably all windings can only be permeated by field lines of one direction.

[0041] According to the invention, a sound transducer is comprised of an impulse generator according to the invention and a resonating body, wherein the resonating body has a mechanical operative connection with the coil, so that when the coil is energized, the resonating body is set into vibration and produces a tone.

[0042] Four exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawing. It shows: Fig. 1 a longitudinal section of a pulse generator with a constant width of the yoke gap, Fig. 2a a longitudinal section of a pulse generator with a yoke gap with a conical longitudinal section, Fig. 2b an enlarged representation of the yoke gap with conical longitudinal section of the pulse generator made of Fig. 2a, Fig. 3a a longitudinal section of a pulse generator with a yoke gap with conical longitudinal section, Fig. 3b an enlarged representation of the yoke gap with conical longitudinal section of the impulse generator made of Fig. 3a, and Fig. 4 a longitudinal section of a pulse generator with a conical longitudinal section and a coil arranged in a body.

[0043] Identical or functionally equivalent parts or features are identified by the same reference numerals in the detailed description of the figures below. Likewise, not all identical or functionally equivalent parts or features in the figures are assigned a reference number.

[0044] Fig. Figure 1 shows a longitudinal section of a first pulse generator 1. The pulse generator 1 is symmetrical about a central axis M. Preferably, the pulse generator 1 has a circular cross-section, wherein the cross-section intersects the central axis M orthogonally. The cross-section of the pulse generator 1 can also have the shape of a polygon, in particular a quadrilateral or an oval.

[0045] The pulse generator 1 comprises a yoke 10 with a yoke gap 15, a permanent magnet 30 and a coil 50 arranged on a carrier element 70.

[0046] The yoke 10 is made of a ferromagnetic material, for example iron or an iron alloy.

[0047] The yoke 10 is designed in two parts and comprises a first yoke element 20 and a second yoke element 25. The yoke 10 can also be designed in one part.

[0048] The first yoke element 20 is cup-shaped and has a circular cross-section, the cross-section intersecting the central axis M of the pulse generator 1 orthogonally. The cup-shaped first yoke element 20 has a side surface 21 with at least a partially free area. This side surface 21 has an overhang 22 extending in the direction of the central axis M of the pulse generator 1. The first yoke element 20 is arranged symmetrically with respect to the central axis M of the pulse generator 1. The first yoke element 20 can also have a polygonal, in particular quadrilateral, cross-section.

[0049] The second yoke element 25 is circular and arranged at least partially within the side surface 21 with the at least partially free surface of the first yoke element 20, symmetrically to the central axis M of the pulse generator 1. The second yoke element 25 can also be polygonal, in particular quadrilateral.

[0050] An annular yoke gap 15 is formed between the overhang 22 of the first yoke element 20 and the second yoke element 25. The yoke gap 15 is arranged annularly around a longitudinal axis L, preferably symmetrically. Preferably, the longitudinal axis L and the central axis M of the pulse generator 1 are coaxial with each other. The yoke gap 15 has a width B, which is constant.

[0051] The width B of the yoke gap 15 is smaller than the distance A of the coil 50 to the yoke gap or the end face 11 of the yoke 10. Preferably, 0 << A < B. The distance A preferably has at least the length of the maximum amplitude of the coil in oscillation. The distance A of the coil to the yoke gap is preferably less than 1 cm. The width of the yoke gap is preferably more than 0.5 cm.

[0052] The yoke gap 15 is filled exclusively with air. An insulating material, for example a material with a permittivity less than or equal to 8, may also be present within the yoke gap 15.

[0053] More than one yoke gap 15 can be formed. For example, two, three, four, or more yoke gaps 15 can be formed. The yoke gaps 15 can be arranged along an imaginary circle, along a line, or symmetrically to each other.

[0054] The second yoke element 25 is mechanically connected to the permanent magnet 30. The second yoke element 25 can be mechanically connected to the permanent magnet 30 via a screw connection, an adhesive connection and / or a snap-fit ​​connection.

[0055] The permanent magnet 30 is also mechanically connected to the first yoke element 20. The first yoke element 20 can be mechanically connected to the permanent magnet 30 via a screw connection, an adhesive connection, and / or a snap-fit ​​connection. The first yoke element 20 and the second yoke element 25 are mechanically connected to each other via the permanent magnet 30.

[0056] The permanent magnet 30 is arranged symmetrically to the central axis M of the pulse generator 1. The permanent magnet 30 has a positive pole 31 and a negative pole 32. The negative pole 32 is mechanically connected to the first yoke element 20 directly or via an adhesive bond. The positive pole 31 is mechanically connected to the second yoke element 25 directly or via an adhesive bond.

[0057] The permanent magnet 30 is preferably designed as a neodymium-iron-boron magnet, as a samarium-cobalt magnet or as a ferrite magnet.

[0058] A magnetic field 40 surrounds the permanent magnet 30, with the magnetic field 40 radiating from the positive pole 31 towards the negative pole 32. The positive pole 31 is often referred to as the north pole and the negative pole 32 as the south pole. Due to its good ferromagnetic properties and the resulting high permittivity, the yoke 10 conducts the magnetic field 40. Because of the good magnetic properties of the ferromagnetic material, the stray field is generally small and the losses are low. The yoke gap 15 causes an increase in magnetic resistance, which in turn increases the proportion of the stray field. The stray field that forms in the region of the yoke gap 15 is defined as the yoke gap stray field 42.

[0059] The magnetic field 40 comprises, in the area of ​​the yoke gap 15, a yoke gap main field 41, which is arranged inside the yoke gap 15, and the yoke gap stray field 42 just introduced, which forms outside, but directly in the area of ​​the yoke gap 15.

[0060] The main yoke split field 41 and the scatter field 42 are in Fig. 1 indicated by dashed lines. Due to the symmetrical design of the yoke gap 15 along the longitudinal axis L of the yoke gap 15, the main yoke gap field 41 within the yoke gap 15 is homogeneous.

[0061] The yoke gap leakage field 42 forms symmetrically when the yoke gap 15 is symmetrical along the longitudinal axis L. The yoke gap leakage field 42 is arc-shaped. The yoke gap leakage field 42 emerges particularly in the edge region 23 of the overhang 22 of the first yoke element 20 and re-enters in the edge region 23 of the second yoke element 25. The magnetic field 40 is weaker the further it is from the yoke gap 15. It is therefore recommended to position the coil 50 as close as possible to the yoke gap 15 so that the yoke gap leakage field 42 is strong enough to cause the coil 50 to oscillate when a corresponding current is applied.

[0062] The coil 50 has windings 51. The windings 51 of the coil 50 preferably run parallel to the annular yoke gap 15, so that the coil is also annular in shape. The windings 51 of the coil 50 are preferably arranged in a plane E. The windings 51 of the coil 50 can be meandering. The coil 50 can also be arranged in several planes E. The coil 50 can be configured as a helical coil.

[0063] During sound generation, coil 50 is subjected to a variable current signal. This variable current signal can take the form of a square wave, a sine wave, a trapezoidal wave, or a triangle wave. The variable current signal has both a positive and a negative component, with the positive and negative components being approximately equal in both magnitude and duration.

[0064] The coil 50 is arranged such that the stray field 52 of the yoke gap 15 penetrates it with sufficient intensity so that, depending on the current state, a force acts on the coil 50 and the coil 50 begins to oscillate. The coil 50 is always arranged outside the yoke gap 15. The coil 50 is arranged along the longitudinal axis L of the yoke gap 15 at a distance from the end face 11 of the yoke 10 on which the yoke gap 15 is formed.

[0065] The circular arrangement of the coil 50 ensures that the force acting on the coil 50 is symmetrical around the central axis M of the pulse generator 1. This makes the mounting or suspension of the coil 50 extremely simple. Furthermore, tilting of the coil 50 during oscillation is virtually eliminated.

[0066] The coil 50 is arranged on a support element 70. The support element 70 is preferably capable of oscillation. Either the support element 70 itself or a resonating body mechanically connected to the support element 70 is set into vibration by the oscillating movement of the coil 50 and produces a tone.

[0067] In Fig. Figure 2a shows a second embodiment of a pulse generator 101 according to the invention. The second embodiment is almost identical to the first embodiment shown in Figure 2a. Fig. 1. The first and second embodiments differ exclusively in the geometric design of the yoke gap 115 and the first and second yoke elements 120, 125, which is why all further components are described in the first embodiment. The yoke 110 differs only in the area of ​​the yoke gap 115, which is why, excluding the area of ​​the yoke gap 115, reference is also made to the first embodiment.

[0068] The yoke gap 115 is formed by the overhang 122 of the first yoke element 120 and the second yoke element 125.

[0069] The longitudinal section of the yoke gap 115 is trapezoidal. The yoke gap 115 tapers from the end face 111 of the yoke 110, which is located directly apart from the coil 50, towards the permanent magnet 30. The taper is continuous and has a constant gradient.

[0070] The width B of the yoke gap 115 along its longitudinal axis L is of varying dimensions. The width B of the section of the yoke gap 115 immediately adjacent to the coil 50 is larger than the width B of the section closer to the permanent magnet 30. The yoke gap 115 may be tapered in sections.

[0071] Fig. Figure 2a shows that the coil 50 has an inner section 54 and an outer section 56. As indicated in the figure, the winding direction of the inner section 54 and the outer section 56 about the longitudinal axis L is different or vice versa. Between the inner section 54 and the outer section 56 is a coil center 55, which preferably has no winding and preferably corresponds to a geometric center of the yoke gap 115.

[0072] In Fig. 2b is an enlarged representation of the area of ​​the yoke gap 115 of the impulse generator 101. Fig. 2a shown. Due to the trapezoidal longitudinal section of the yoke gap 115, the magnetic field 40 is more deflected and aligned towards the coil 50 than in embodiment one. The in Fig. The dashed lines of the magnetic field 40 shown in Figure 2b are already arc-shaped within the yoke gap 115 in the direction of the coil 50. This has the advantage that the yoke gap stray field 42 has a higher intensity in the direction of the coil 50 than in the direction of the permanent magnet 30.

[0073] This significantly improves efficiency, as the yoke gap stray field 42 passing through the coil 50 is higher than in embodiment one. As a result, the coil 50 can be energized with a lower current while applying the same required force.

[0074] In Fig. Figure 3a shows a third embodiment of a pulse generator 201 according to the invention. The third embodiment is almost identical to the first embodiment from Fig. 1. The first and second embodiments differ exclusively in the geometric design of the yoke gap 215 and the first and second yoke elements 220, 225, which is why all further components are described in the first embodiment. The yoke 210 differs only in the area of ​​the yoke gap 215, which is why, excluding the area of ​​the yoke gap 215, reference is also made to the first embodiment.

[0075] The yoke gap 215 is formed by the overhang 222 of the first yoke element 220 and the second yoke element 225.

[0076] The longitudinal section of the yoke gap 215 is conical. The yoke gap 215 tapers from the end face 211 of the yoke 210, which is arranged directly spaced from the coil 50, towards the permanent magnet 30. The taper is continuous and has discontinuous gradients, with the gradient preferably increasing towards the coil.

[0077] The width B of the yoke gap 215 along its longitudinal axis L varies. The width B of the section of the yoke gap 215 immediately adjacent to the coil 50 is larger than the width B of the section closer to the permanent magnet 30. The yoke gap 215 may be tapered in sections.

[0078] In Fig. Figure 3b is an enlarged representation of the area of ​​the conical yoke gap 215 of the impulse generator 201. Fig. Figure 3a shows the main yoke gap field 41 and the yoke gap stray field 42, indicated by dashed lines. Due to the conically shaped yoke gap 215, the yoke gap stray field 42 is more strongly oriented towards coil 50. The field lines are already arc-shaped within the yoke gap 215 in the direction of coil 50. As a result, the yoke gap stray field 42 has a higher intensity in the area of ​​coil 50, which increases the efficiency because the force acting on coil 50 increases with a constant current flowing through it.

[0079] Fig. Figure 4 shows a fourth embodiment of the pulse generator 301 according to the invention, wherein the yoke 210 and the permanent magnet 30 and their arrangement are the same as in the embodiment shown in Figure 4. Fig. 3a are trained.

[0080] The fourth embodiment differs with regard to the arrangement and design of the coil 350.

[0081] The coil 350 is arranged within a support element 370. The coil 350 is arranged in several, preferably four, planes E, one plane E intersecting the central axis M of the pulse generator 301 orthogonally. The coil 350 can also be arranged in only one plane E.

[0082] The support element 370 is mechanically connected to the yoke 210 by means of an elastic adhesive layer 390.

[0083] The carrier element 370 can be a circuit board 380, in particular a multilayer circuit board 380. Preferably, the coil 350 is arranged as a helical coil on the circuit board 380. Preferably, the helical coil is arranged on several layers of the multilayer circuit board 380. The helical coil can be designed in a meandering shape.

[0084] The support element 370 can be a glass pane, a plastic body, or a body made of another material. The coil 350 can be encased, glued, screwed, or clamped within the glass pane, plastic body, or body made of another material. Preferably, an elastomeric adhesive or a double-sided adhesive elastomeric ring interlayer is used as the elastic adhesive material. Elastomeric adhesives or this interlayer are characterized by their good elastic properties, allowing the coil to be arranged to oscillate.

[0085] In particular, the support element 370 can be a glass pane or a plastic body or a body made of another material that is part of a vehicle, especially an automobile.

[0086] When the coil 350 is set into vibration within the carrier element 370, the carrier element 370 is also set into vibration. This results in a sound being emitted.

[0087] The support element 370 with coil 350 is mechanically fixed to the end face 211 of the yoke 210 with yoke gap 215 by means of an adhesive bond. The support element 370 with coil 350 can also be mechanically fixed to the yoke 210 by means of a screw connection or a clamp connection.

[0088] The yoke gap 215 can have any longitudinal section. The longitudinal section of the yoke gap 215 can be conical, trapezoidal, polygonal, in particular rectangular or square.

[0089] The winding direction of the coil 50 can be reversed in embodiments one to four in the region of the yoke gap 15. For example, the coil 50 can be wound – as in Fig. 2 is indicated - in the area of ​​its outer radius it is wound in the opposite direction to the inner radius.

[0090] The coil 50 of embodiments one to four can also be wound around an axis that is spaced apart from the longitudinal axis L of the pulse generator 1. This means that the coil 50 can be arranged offset from the pulse generator 1 in one or more planes. Reference symbol list 1 pulse generator 10 yoke 11 Front 15 Jochspalt 20 First yoke element 21 side surface 22 Overhang 23 edge area 25 Second yoke element 30 permanent magnets 31 Positive pole 32 Negative terminal 40 Magnetic field 41 Jochspalthauptfeld 42 Yoke split scatter field 50 coil 54 inner section 55 Coil center 56 outer section 51 windings 70 support element 101 Impulse generators 110 yoke 111 Front 115 Jochspalt 120 First yoke element 122 Overhang 125 Second yoke element 201 Impulse generators 210 yoke 211 Front 215 Jochspalt 220 First yoke element 222 Overhang 225 Second yoke element 220 First yoke element 225 Second yoke element 301 Pulse generator 350 coil 370 support element 380 circuit board 390 adhesive layer M Center axis pulse generator L Longitudinal axis Yoke gap B Wide yoke gap B1 Wide Coil Level E

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