ELECTRODYNAMIC VIBRATION EXCITER

Abstract

An actuator, including an electric drive for converting electrical signals into mechanical forces and/or deflections. The drive having at least one coil through which the current of the electrical signal can flow and having at least two magnets which can electromagnetically interact with the coil. The actuator being designed to excite a body which can be connected to the actuator, in particular a flat body, to vibrate, as a result of which the body can emit acoustic sound. The two magnets are arranged such that they form a substantially straight air gap between them, the coil being arranged in the air gap.

Claims

1. An actuator, comprising: an electric drive for converting electrical signals into mechanical forces and/or deflections, the drive having at least one coil through which the current of the electrical signal can flow and having at least two magnets which can electromagnetically interact with the coil, the actuator being designed to excite a body which can be connected to the actuator, to vibrate, as a result of which the body can emit acoustic sound, wherein the two magnets are arranged such that they form a substantially straight air gap between them, the coil being arranged in said air gap.

2. The actuator as claimed in claim 1, wherein the two magnets have a mutually opposite/inverse orientation of the magnetization direction, the magnetization direction of the two magnets being substantially parallel to the vertical direction of the air gap and/or substantially parallel to the deflection direction of the coil in the air gap.

3. The actuator as claimed in claim 1, wherein the actuator is designed such that a respective pole plate is arranged above and below each magnet with respect to the vertical direction of the air gap, said pole plates each having the maximum thickness at the air gap and being designed to taper away from the air gap.

4. The actuator as claimed in claim 1, wherein at least one, pole plate is designed such that the outer surface of the pole plate facing away from the magnet, such that the outer surface which is arranged opposite the connecting surface or adjoining the magnet, has at least one planar partial surface and/or one plateau, in particular in each case.

5. The actuator as claimed in claim 4, wherein the outer surface of a pole plate facing away from the magnet or of each pole plate has a planar partial surface and/or a plateau adjoining the air gap and/or a planar partial surface and/or plateau on the averted side of the air gap.

6. The actuator as claimed in claim 1, wherein the coil is substantially rectangular and/or substantially rectangular with rounded corners.

7. The actuator as claimed in claim 1, wherein the coil comprises a coil carrier which is formed from non-ferromagnetic material and has a coefficient of thermal conductivity of at least 20 W/(m K).

8. The actuator as claimed in claim 7, wherein the coil carrier has a core which is arranged in the interior of the coil, the coil carrier having a respective covering bar above and below the coil, with respect to the vertical direction of the air gap, and covering plates each connected to the covering bars and each being oriented substantially parallel to the plane along the air gap and being arranged on both sides of the coil, so that the covering bars and the covering plates frame the coil in a continuous manner.

9. The actuator as claimed in claim 1, wherein the actuator has a spring arrangement which is designed to bias the coil into an inoperative position, the spring arrangement being designed to bias the coil along each possible direction of movement, returning it to the inoperative position.

10. The actuator as claimed in claim 9, wherein the spring arrangement has at least one spring unit which is arranged above the magnets and the pole plates in relation to the vertical direction of the air gap and one spring unit is arranged below the magnets and the pole plates in relation to the vertical direction of the air gap.

11. The actuator as claimed in claim 9, wherein one spring unit or both spring units, in each case, has/have two spring elements which run substantially in the direction of the air gap in an inoperative state, the spring elements having a curved and/or spiral and/or double-S shape in the inoperative state.

12. The actuator as claimed in claim 1, wherein the actuator with the connected body is designed as a bending wave emitter and/or is designed such that the actuator excites/can excite the body to vibrate its body structure, as a result of which the body surrounded by air emits sound waves.

13. The actuator as claimed in claim 1, wherein the actuator has at least one connecting element which fixes the two magnets and/or all the pole plates jointly and/or is firmly connected to them, the actuator having two connecting elements on two opposite sides of the actuator, the connecting elements each fixing the two magnets and/or all the pole plates jointly and/or being firmly connected to them.

14. The actuator as claimed in claim 1, wherein the coil is arranged substantially centrally and/or in the middle in the air gap in the inoperative state.

15. The actuator as claimed in claim 1, wherein the actuator has at least one pole termination plate which is arranged between the coil and one of the two magnets, the pole termination plate being electrically conductive and not being mechanically connected to the coil or the coil carrier.

16. The actuator as claimed in claim 1, wherein the at least one pole termination plate delimits the air gap in the horizontal direction and is oriented along the vertical direction of the air gap, the at least one pole termination plate being mechanically connected to one of the magnets and/or the pole plates of this magnet here, the respective magnet and/or the pole plates associated with it being connected by way of their surfaces respectively adjoining the air gap to the pole termination plate.

17. The actuator as claimed in claim 1, wherein the actuator has two pole termination plates which each delimit the air gap on one side in the horizontal direction and are each oriented along the vertical direction of the air gap, the two pole termination plates each being mechanically connected to one of the magnets and/or the pole plates of this magnet here and the pole termination plates, in each case by way of the outer side facing the magnet and its pole plates, being designed to be adapted to the contour of the adjoining outer sides of the magnet and its pole plates.

18. The actuator as claimed in claim 1, wherein the body is a flat body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In the drawings, in a schematic illustration,

[0039] FIG. 1 shows an example of a conventional loudspeaker, and

[0040] FIGS. 2 to 12 show exemplary embodiments of the actuator or exemplary parts of the actuator.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0041] FIG. 1 shows the exemplary structure of a conventional, rotationally symmetrical loudspeaker 9, from which the structure of a conventional vibration exciter 10 can be seen by detaching the diaphragm 7, the coil carrier 4 and the basket 5. A permanent magnet 2 is enclosed by two pole plates composed of ferromagnetic material 1. A circular, current-carrying coil 3 which is only connected to the pole plates via an elastic suspension 8 (usually made of textile fabric) is located in the air gap 11 between the two pole plates. Exciting the coil 3 with an electrical signal creates a force on the coil, this force being introduced into the diaphragm 7 via the coil carrier 4. The vibrating diaphragm 7 is connected to the basket 5 via the mechanically soft bead 6, the basket in turn being firmly connected to the pole plate 1. In previously known electrodynamic vibration exciters 10, the connection to a flat structure is made directly via the coil carrier 4. The basket 5, the bead 6 and the diaphragm 7 are dispensed with in this case.

[0042] FIG. 2 shows, by way example, the structure of the magnet system of an electrodynamic vibration exciter or actuator. Two identical magnets 12 are arranged symmetrically with respect to the mirror plane 16, but their magnetic orientation is inverted. An upper pole plate 13 and a lower pole plate 14 are arranged symmetrically with respect to the mirror plane 16 on each of the two magnets. The magnetic flux 15 is consequently oriented in opposite directions in the upper and the lower air gap 17.

[0043] A substantially rectangular coil 19 situated on the mirror plane 16 is illustrated by way of example with reference to FIG. 3. The coil 19 is wound around a core 18 composed of a non-ferromagnetic material.

[0044] FIG. 4 shows a cross section through a structure, symmetrical with respect to the mirror plane 16, of an exemplary coil 19 with an enclosure. The coil 19 wound around the core 18 is covered laterally by covering plates 20. The coil can optionally be covered by additional covering bars 21 on its top and bottom. The core 18 and the covering plates 20 and covering bars 21 are part of the coil carrier.

[0045] FIG. 5 illustrates, by way of example, the direction of the magnetic flux 15, the electric flux in the coil 23 and the resulting force excitation 22 in the exemplary electrodynamic vibration exciter. The magnetic fluxes 15 between the upper pole plates 13 and the lower pole plates 14 due to the magnets 12 are orthogonal to the electrical fluxes 23, this resulting in a force excitation 22 proportional to the electrical excitation signal of the coil. The coil and thus also its electrical flux 23 lie in the mirror plane of the electrodynamic vibration exciter.

[0046] FIG. 6 shows, by way of example, the synchronization of the two mirror halves by means of connecting elements 24. The two mirror halves, each consisting of a magnet 12, an upper pole plate 13 and a lower pole plate 14, are connected to one another by two connecting elements 24, the aim of this being to synchronize their movement. Furthermore, the respective upper pole plates 13 and the respective lower pole plates 14 are positioned at their mutual distance and in their position corresponding to a reflection at the mirror plane 16 by the connecting elements 24. The upper pole plates 13 and the lower pole plates 14 project laterally beyond the magnets 12 by the thickness of the connecting elements 24 in order to completely enclose the connecting elements 24.

[0047] FIG. 7 illustrates an exemplary elastic suspension of the magnets 12 and the pole plates 13, 14 by means of bending springs 25, 26. The bending springs 25, 26 are cut in the region of the outer covering plates of the coil 20, so that the covering plates 20 can be inserted through the bending springs 25, 26, this allowing the coil 19 to be positioned and centered between the pole plates 13, 14 and the magnets 12.

[0048] FIG. 8 shows, by way of example, the orientation of the coil 19 between the pole plates 13, 14 by means of orientation planes 31, 32. Imaginary orientation planes 31, 32 are located at the level of half the thickness of the sides of the pole plates 13, 14 facing the air gaps 17. The upper orientation plane 31 and, respectively, lower orientation plane 32 is oriented on the upper pole plates 13 and lower pole plates 14. The coil 19 is preferably oriented in the air gaps 17 such that it intersects the respective orientation plane 31, 32 at half its height. However, it can be positioned with a deliberate displacement in relation to the orientation planes 31, 32 in order to achieve a different characteristic, for example progressive or degressive characteristics, for the electromagnetic excitation.

[0049] FIG. 9 shows an exemplary plan view of a bending spring. The bending springs are preferably designed symmetrically with respect to the mirror plane 16. The outer regions of the bending spring 27 are connected to the pole plates 13, 14. The middle part of the bending spring 29 has a cutout 30, so that the covering plates of the coil 20 can be inserted through it. The transition regions 28 between the outer regions 27 and the middle part 29 can be shaped as desired, but are preferably constructed with mirror symmetry.

[0050] FIG. 10 shows an exemplary actuator in which the coil 19 is arranged between the pole plates 13, 14 in a manner spaced apart by means of an air gap 17 in each case. A respective pole plate 13 and 14 is arranged on and below the magnet 12 in a manner enclosing it on both sides. The magnet 12 and the pair of pole plates 13, 14 each have a pole termination plate 33 composed of electrically conductive material on their surface jointly adjoining the air gap, the pole termination plates each being secured by means of an adhesive layer, not shown, by way of example. The pole termination plate 33 has, by way of example, an electrical conductivity of at least 1 MS/m.

[0051] FIG. 11 shows an exemplary actuator in which the pole plates 13, 14 are respectively arranged above and below the two magnets 12 on both sides. Here, the pole plates 13, 14 each have two plateaus 34 and 35 on the outer surface facing away from the magnet 12, the thickness of the pole plate adjoining the air gap in each case and being determined by the plateau 34 and the surface facing the magnet 12 being greater than the thickness of the pole plate on the side opposite the air gap, this thickness being determined between the plateau 35 and the surface facing the magnet 12. The pole plates 13, 14 each have an inclined course, for example a linear change in thickness, between the plateaus 34 and 35.

[0052] An actuator is illustrated by way of example with reference to FIG. 12. The coil 19 is arranged between the pole plates 13, 14 in a manner spaced apart by means of an air gap 17 in each case. A respective pole plate 13 and 14 is arranged on and below the magnet 12 in a manner enclosing it on both sides. The magnet 12 and the pair of pole plates 13, 14 each have a pole termination plate 33 composed of electrically conductive material on their surface jointly adjoining the air gap 17. The coil 19 is suspended from bending springs 25, 26 and is covered laterally by covering plates 20 and is covered on its top side and bottom side by additional covering bars 21. The coil 19 can vibrate in a manner suspended in mirror plane 16 in this way. Said FIG. 12 also illustrates the orientation of the coil 19 between the pole plates 13, 14 by means of orientation planes 31, 32.