Electrodynamic actuator for a speaker or a sound transducer with improved damping

Patent metadata

Field	Value
Publication number	US-12137333-B2
Application number	US-202217939948-A
Country	US
Kind code	B2
Filing date	Sep 7, 2022
Priority date	Sep 9, 2021
Publication date	Nov 5, 2024
Grant date	Nov 5, 2024

Abstract

An electrodynamic actuator ( 1 a . . . 1 c ) for a plate like structure ( 25 ) or membrane ( 2 ) is disclosed, which comprises a voice coil ( 7, 7 a, 7 b ), a magnet system ( 8 ) and a plurality of arms ( 17 a . . . 17 t ) coupling the voice coil ( 7, 7 a, 7 b ) and the magnet system ( 8 ) in a movable manner. The arms ( 17 a . . . 17 t ) are made of a metal with a fatigue strength of at least 370 N/mm 2 or an ultimate tensile strength of at least 1100 N/mm 2 . Each of the arms ( 17 a . . . 17 t ) comprises at least two arm sections (s, s 1 , s 2 ), which are arranged movable to each other, and which are connected to each other by means of a damping material ( 18 a . . . 18 g ) with a tensile storage modulus of 0.1-6000 MPa and a tensile loss factor of at least 0.1, each measured at room temperature of 20° C. Moreover the invention relates to speaker ( 5 ) and an electrodynamic transducer ( 26 a, 26 b ) with such an electrodynamic actuator ( 1 a . . . 1 c ) and a method of manufacturing an intermediate product for such an electrodynamic actuator ( 1 a . . . 1 c ).

First claim

What is claimed is:

1. An electrodynamic actuator ( 1 a . . . 1 c ), which is designed to be connected to a backside of a plate like structure ( 25 ) or membrane ( 2 ) opposite to a sound emanating surface (S) of the plate like structure ( 25 ) or the membrane ( 2 ) and which comprises
at least one voice coil ( 7 , 7 a , 7 b ), which has an electrical conductor in the shape of loops running around a coil axis (A) in a loop section;
a magnet system ( 8 ) being designed to generate a magnetic field (B) transverse to the conductor in the loop section; and
an arm arrangement ( 14 a . . . 14 j ) of a plurality of arms ( 17 a . . . 17 t ) coupling the at least one voice coil ( 7 , 7 a , 7 b ) and
a) the magnet system ( 8 ) and allowing a relative movement between the voice coil ( 7 , 7 a , 7 b ) and said magnet system ( 8 ) in an excursion direction (C) parallel to the coil axis (A); or
b) a movable part ( 28 ) of the magnet system ( 8 ) and allowing a relative movement between the voice coil ( 7 , 7 a , 7 b ) and said movable part ( 28 ) of the magnet system ( 8 ) in an excursion direction (C) parallel to the coil axis (A),

wherein
the arms ( 17 a . . . 17 t ) are made of a metal with a fatigue strength of at least 370 N/mm 2 or an ultimate tensile strength of at least 1100 N/mm 2 and wherein
each of the arms ( 17 a . . . 17 t ) comprises at least two arm sections (s, s 1 , s 2 ), which are arranged movable to each other and which are connected to each other by means of a damping material ( 18 a . . . 18 g ) with a tensile storage modulus of 0.1-6000 MPa and a tensile loss factor of at least 0.1, each measured at room temperature of 20° C.

2. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the arms ( 17 a . . . 17 t ) comprise more than two arm sections (s, s 1 , s 2 ), wherein each two of them are connected to each other by means of the damping material ( 18 a . . . 18 g ).

3. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the at least two arm sections (s, s 1 , s 2 ) run next to each other forming a longitudinal gap in-between, in which the damping material ( 18 a . . . 18 g ) is arranged.

4. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that a ratio between a length of said gap to its width is >20.

5. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the at least two arm sections (s, s 1 , s 2 ) are arranged at a distance (b 1 . . . b 4 ) measured in the direction of the coil axis (A).

6. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 5 , characterized in that the distance (b 1 . . . b 4 ) between the at least two arm sections (s, s 1 , s 2 ) being connected by means of the damping material ( 18 a . . . 18 g ) is in a range of 5 μm≤d≤100 μm.

7. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the at least two arm sections (s, s 1 , s 2 ) are arranged at a distance (b 1 . . . b 4 ) measured perpendicularly to the direction of the coil axis (A).

8. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 7 , characterized in that the distance (b 1 . . . b 4 ) between the at least two arm sections (s, s 1 , s 2 ) being connected by means of the damping material ( 18 a . . . 18 g ) is in a range of 20 μm≤d≤100 μm.

9. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the gap is made by etching and/or by use of a laser.

10. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the arms ( 17 a . . . 17 t ) are L-shaped, U-shaped, S-shaped, shaped like a bow or shaped like a meander when viewed in a direction parallel to the coil axis (A).

11. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 10 , characterized in that the at least two arm sections (s, s 1 , s 2 ) are concatenated in a longitudinal direction of the respective arm ( 17 a . . . 17 t ) and
alternatingly are bent in a different sense of direction or
alternatingly are straight and bent.

12. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 11 , characterized in that a distance (b 1 . . . b 4 ) between the at least two arm sections (s, s 1 , s 2 ) being connected by means of a damping material ( 18 a . . . 18 g ), which is measured perpendicularly to the direction of the coil axis (A), is in a range of 50 μm≤d≤400 μm.

13. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the at least two arm sections (s, s 1 , s 2 ) consist of different materials.

14. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the arms ( 17 a . . . 17 t ) are coated.

15. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the arms ( 17 a . . . 17 t ) are coated with the damping material ( 18 a . . . 18 g ).

16. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 10 , characterized in that the at least one of the plurality of arms ( 17 a . . . 17 t ) is encompassed by or embedded in the damping material ( 18 a . . . 18 g ).

17. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 16 , characterized in that a thickness of the damping material ( 18 a . . . 18 g ), which is measured in the direction of the coil axis (A), is in a range of 20 μm≤d≤200 μm.

18. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 14 , characterized in that the coating consist of or contains sprayed silicone.

19. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the arms ( 17 a . . . 17 t ) together with the damping material ( 18 a . . . 18 g ) are coated.

20. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the at least two arm sections (s, s 1 , s 2 ) have a different stiffness.

21. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that the arms ( 17 a . . . 17 t ) are made of or comprise steel, brass, bronze, molybdenum or tungsten.

22. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 21 , characterized in that the arms ( 17 a . . . 17 t ) are made of a stainless steel.

23. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 22 , characterized in that the arms ( 17 a . . . 17 t ) are made of a cold-rolled stainless steel with a fatigue strength in a range of 370 to 670 N/mm 2 or an ultimate tensile strength in a range of 1100 to 2000 N/mm 2 .

24. The electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 , characterized in that at least some of said arms ( 17 a . . . 17 t ) are electrically connected to the at least one voice coil ( 7 , 7 a , 7 b ).

25. A speaker ( 5 ), characterized by an electrodynamic actuator ( 1 a . . . 1 c ) as claimed in claim 1 and a membrane ( 2 ), which is fixed to the at least one coil ( 7 , 7 a , 7 b ) and to the magnet system ( 8 ).

26. The electrodynamic actua

Assignees

• Sound Solutions Int Co Ltd

Inventors

• Hintennach Andreas
• Mefleh Manuel
• Polat Murat
• Otto Gustav
• Gelbmann Patrick

Classifications

• H04R9/06

  Loudspeakers · CPC title

• H04R9/027

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• H04R2440/05

  Aspects relating to the positioning and way or means of mounting of exciters to resonant bending wave panels · CPC title

• H04R2400/07

  Suspension between moving magnetic core and housing · CPC title

• H04R9/025

  Magnetic circuit · CPC title