Multi magnet electrodynamic acoustic transducer and electroacoustic system

Patent metadata

Field	Value
Publication number	US-11889284-B2
Application number	US-202217701999-A
Country	US
Kind code	B2
Filing date	Mar 23, 2022
Priority date	Mar 25, 2021
Publication date	Jan 30, 2024
Grant date	Jan 30, 2024

Abstract

An electrodynamic acoustic transducer (1) is disclosed, which comprises a frame and/or a housing (2), a membrane (3), a magnet system (6) with a plurality of center magnets (7a . . . 7d, 7, 7′) having different magnetic orientations (M1 . . . M4) and a coil arrangement (10) with a plurality of voice coils (11a . . . 11d), which are movably arranged relative to the magnet system (6) in an excursion direction (z). The ratioAg·hmAm·wg=lg·htp·hmAm·wgis below 1, wherein wg denotes the mean width of all airgaps (E) within the magnet system (6), Ag denotes the sum of all airgap areas within the magnet system (6), hm denotes the mean height of the center magnets (7a . . . 7d, 7, 7′) and Am denotes the total area of the center magnets (7a . . . 7d, 7, 7′). Moreover, the invention relates to an electroacoustic system (19), which comprises an electrodynamic acoustic transducer (1) of the above kind and a control circuit (CC) connected to the coil arrangement (10).

First claim

What is claimed is:

1. An Electrodynamic acoustic transducer, comprising:
a frame and/or a housing;
a membrane fixed to said frame or said housing;
a magnet system comprising:
a plurality of center magnets having different magnetic orientations;
a plurality of center top plates each of which being arranged adjacent to one of said center magnets;
a common bottom plate arranged adjacent to said center magnets and opposite to the center top plates; and
an outer magnet circuit region surrounding the center magnets and the center top plates,
wherein airgaps are formed between the center top plates and between the center top plates and the outer magnet circuit region;

a coil arrangement comprising a plurality of voice coils, which are attached to the membrane and which are movably arranged relative to the magnet system in an excursion direction, wherein each of the voice coils comprises an electrical conductor in the shape of loops running around a separate coil axis in a loop section, wherein the coil axes are parallel to the excursion direction, and wherein each of the voice coils surrounds a top plate of the magnet system;
wherein the magnet system is designed to generate a magnetic field transverse to the conductors of the voice coils in the loop sections, and
wherein the ratio

A
g

·

h
m

A
m

·

w
g

=

l
g

·

h
tp

·

h
m

A
m

·

w
g

is below 1,
w g denotes the mean width of all airgaps within the magnet system, which is the average value of diameters of virtual circles inscribed in the airgaps between the center top plates and in the airgaps between the center top plates and the outer magnet circuit region, wherein axes of the virtual circles are parallel to the excursion direction,
A g denotes the sum of all airgap areas within the magnet system, which is the mean height h tp of the center top plates measured in a direction parallel to the excursion direction multiplied by the airgap length l g , which is the total length of an airgap center line connecting the centers of said virtual circles,
h m denotes the mean height of the center magnets measured in a direction parallel to the excursion direction, and
A m denotes the total area of the center magnets when viewed in a direction parallel to the excursion direction.

2. Electrodynamic acoustic transducer according to claim 1 , wherein the outer magnet circuit region comprises:
elongations of the bottom plate in the excursion direction which together with the bottom plate form a pot, or
side plates adjacent to the bottom plate which together with the bottom plate form a pot, or
outer magnets adjacent to the bottom plate and outer top plates adjacent to the outer magnets.

3. The electrodynamic acoustic transducer according to claim 1 , wherein the airgap center line is broken in regions where the diameter of the associated virtual circle exceeds two times the diameter of the smallest virtual circle in the airgaps.

4. The electrodynamic acoustic transducer according to claim 1 , wherein the center magnets are arranged in a matrix-style when viewed in a direction parallel to the excursion direction, wherein adjacent center magnets have different magnetic orientations.

5. The electrodynamic acoustic transducer according to claim 1 , wherein the center magnets are each shaped as a circular segment when viewed in a direction parallel to the excursion direction.

6. The electrodynamic acoustic transducer according to claim 1 , wherein the areas of the center magnets are the same when viewed in a direction parallel to the excursion direction.

7. The electrodynamic acoustic transducer according to claim 1 , wherein the center magnets with regards to their magnetic orientation are arranged point symmetric or rotational symmetric by a rotation angle of ≤180° around a transducer axis, which is parallel to the coil axes and arranged in the center thereof.

8. The electrodynamic acoustic transducer according to claim 1 , wherein the center magnets with regards to their shape are arranged point symmetric or rotational symmetric by a rotation angle of ≤180° around a transducer axis.

9. The electrodynamic acoustic transducer according to claim 1 , wherein a magnetic flux generated by the center magnets is distributed point symmetric or rotational symmetric by a rotation angle of ≤180° around a transducer axis.

10. The electrodynamic acoustic transducer according to claim 1 , wherein a force factor related to the magnet system and to the coil arrangement is distributed point symmetric or rotational symmetric by a rotation angle of ≤180° around a transducer axis.

11. The electrodynamic acoustic transducer according to claim 1 , wherein a mass of the coil arrangement is distributed point symmetric or rotational symmetric by a rotation angle of ≤180° around a transducer axis.

12. The electrodynamic acoustic transducer according to claim 1 , wherein centers of gravity of the voice coils are distributed point symmetric or rotational symmetric by a rotation angle of ≤180° around a transducer axis.

13. The electrodynamic acoustic transducer according to claim 1 , wherein an area of the center magnets seen in a direction parallel to a transducer axis and lengths of electrical conductors in the loop sections of the of voice coils are distributed point symmetric or rotational symmetric by a rotation angle of ≤180° around the transducer axis.

14. The electrodynamic acoustic transducer according to claim 1 , wherein the magnet system comprises an even number of center magnets.

15. The electrodynamic acoustic transducer according to claim 1 , wherein the magnet system has an overall width, an overall length and an overall height in a Cartesian coordinate system, wherein the overall length is the largest extension of the magnet system and the overall height is its smallest extension and wherein a ratio between the overall length and the overall height is ≥10.

16. The electrodynamic acoustic transducer according to claim 1 , wherein the magnet system has an area seen in a direction parallel to the transducer axis and an overall height measured in the direction parallel to the transducer axis, wherein a ratio between the square root of said area and the overall height is ≥10.

17. The electrodynamic acoustic transducer according to claim 1 , wherein the voice coils are made of metal foils stacked one above another in the direction of a transducer axis with insulating lay

Assignees

• Sound Solutions Int Co Ltd

Inventors

• Reining Friedrich

Classifications

• H04R9/027 Primary

  Air gaps using a magnetic fluid · CPC title

• H04R9/025 Primary

  Magnetic circuit · CPC title

• H04R9/04

  Construction, mounting, or centering of coil · CPC title

• H04R9/045

  Mounting (H04R9/043 takes precedence) · CPC title

• H04R9/06

  Loudspeakers · CPC title