Method and apparatus for a magnetically induced speaker diaphragm

• US 6,108,433 A
• Filed: 01/13/1998
• Issued: 08/22/2000
• Est. Priority Date: 01/13/1998
• Status: Expired due to Fees

• Current Assignee: Turtle Beach Corporation
• Original Assignee: American Technology Incorporated (Emerson Electric Company)
• Inventors: Norris, Elwood G.
• Primary Examiner(s): Kuntz, Curtis A.
• Assistant Examiner(s): Harvey, Dionne N.
• Application Number:
  US09/006,689
• Time in Patent Office: 952 Days
• Field of Search: 381/162, 381/163, 381/164, 381/360, 381/368, 381/176, 381/177, 381/395, 381/421, 381/429, 381/406, 381/408, 367/140
• US Class Current: 381/399
• CPC Class Codes: G10K 9/13 using electromagnetic driving means

Abstract

An ultrasonic emitter device having broad frequency range capacity with relatively large diaphragm displacement compared to typical electrostatic diaphragm movement. The device includes a core member able to establish a variable magnetic field adjacent the core member. A movable diaphragm is stretched along and displaced a short separation distance from the core member to allow an intended range of orthogonal displacement of the diaphragm within a strong portion of the magnetic field. At least one conductive ring disposed on the movable diaphragm within the influence of the variable magnetic field of the core member for enabling current flow through the ring for developing a second magnetic field which interacts with the first magnetic field to repel and relax the diaphragm at a desired frequency for development of a series of compression waves which may be adjusted to include an ultrasonic frequency range.

Claims

1. An ultrasonic emitter device having broad frequency range capacity with relatively large diaphragm displacement compared to typical electrostatic diaphragm movement, said device, comprising:

a core member containing means for establishing a variable magnetic field adjacent the core member;

a movable diaphragm disposed in tension along the core member and displaced a short separation distance from the core member to allow an intended range of orthogonal displacement of the diaphragm with respect to the core member and within a strong portion of the variable magnetic field; and

at least one conductive ring disposed on the movable diaphragm for enabling inductively induced current flow in an orientation which develops a counter, opposing magnetic force which is repelled by the variable magnetic field of the core member at a desired frequency for development of a series of compression waves which may be adjusted to include an ultrasonic frequency range.

2. A device as defined in claim 1, wherein the core member comprises an electromagnet.

3. A device as defined in claim 2, wherein the electromagnet comprises a rigid plate having dimensions slightly larger than dimensions of an active emitting surface of the emitter device.

4. A device as defined in claim 3, wherein the rigid plate comprises a flat plate with uniform variable magnetic field along a surface of the plate most adjacent the movable diaphragm.

5. A device as defined in claim 2, wherein the electromagnet comprises a flexible plate.

6. A device as defined in claim 1, wherein the core member comprises a rigid plate formed of nonmagnetic composition, one surface of the plate including at least one opposing conductive coil having first and second contacts for enabling current flow through the conductive coil.

7. A device as defined in claim 6, wherein the at least one conductive coil is positioned on the rigid plate in a location which is juxtaposed to the at least one conductive ring on the movable diaphragm to enable the at least one conductive coil and at least one opposing conductive ring to cause opposing magnetic fields to interact to develop the compression waves.

8. A device as defined in claim 7, wherein the means for supplying variable current flow includes control means for coordinating current flow to the at least one conductive coil such that the at least one conductive coil generates a variable magnetic field which is capable of enhancing repulsion arising between the at least one coils and at least one ring.

9. A device as defined in claim 1, wherein the diaphragm comprises a thin film, said at least one ring being disposed on one side of the film.

10. A device as defined in claim 9, wherein the film comprises a polymer having isotropic resilient properties across its surface to provide a uniform response to applied tension.

11. A device as defined in claim 10, wherein the polymer comprises Mylar.

12. A device as defined in claim 9, wherein the ring is made of a composition selected from the group consisting of conductive metals, conductive ceramics and superconductive materials.

13. A device as defined in claim 1, wherein the ring is deposited on the diaphragm as a conductive element by vapor deposition.

14. A device as defined in claim 1, comprising a plurality of conductive rings disposed on the diaphragm.

15. A device as defined in claim 14, wherein the plurality of conductive rings are equally spaced along the diaphragm.

16. A device as defined in claim 15, wherein the plurality of conductive rings are disposed in a plurality of rows.

17. A device as defined in claim 1, further comprising a support perimeter in contact with the diaphragm around each of the at least one conductive ring.

18. A device as defined in claim 17, comprising a plurality of conductive rings, each ring including a support perimeter in contact with the diaphragm and providing means for substantially isolating displacement of the diaphragm at each ring from adjacent rings.

22. A device as defined in claim 1, wherein the core comprises an electromagnetic composition and includes means for supplying an alternating current to the means for establishing a variable magnetic field for developing an electromagnetic force inside the core which is operable with respect to the at least one conductive ring to develop the desired diaphragm displacement.

23. A device as defined in claim 22, wherein a plurality of conductive rings are disposed on the diaphragm and develop a collective response to the electromagnetic force of the core to generate the desired relatively large diaphragm displacement.

24. A device as defined in claim 1, wherein the means for establishing the variable magnetic field adjacent the core comprises at least one conductive coil positioned on the core adjacent the at least one conductive ring of the diaphragm.

25. A device as defined in claim 24, comprising a plurality of first conductive rings on the diaphragm and a corresponding plurality of second conductive rings juxtaposed to the first conductive rings on an opposing side of the diaphragm.

26. A device as defined in claim 24, wherein the means for providing the variable magnetic field comprises an alternating current source.

27. A device as defined in claim 26, wherein the plurality of coils of the core are aligned with the plurality of rings of the diaphragm.

19. An ultrasonic emitter device having broad frequency range capacity with relatively large diaphragm displacement compared to typical electrostatic diaphragm movement, said device, comprising:

a core member having means for establishing a variable magnetic field adjacent the core member;

a movable diaphragm disposed in tension along the core member and displaced a short separation distance from the core member to allow an intended range of orthogonal displacement of the diaphragm with respect to the core member and within a strong portion of the variable magnetic field;

a plurality of conductive rings disposed on the movable diaphragm for enabling current flow in an orientation which develops a counter, opposing magnetic force which is repelled by the variable magnetic field of the core member at a desired frequency for development of a series of compression waves which may be adjusted to include an ultrasonic frequency range;

a support perimeter, in contact with the diaphragm and providing means for substantially isolating displacement of the diaphragm at each ring from adjacent rings, wherein the support perimeter for isolating the rings comprises a grid configuration defining a plurality of open displacement cavities at a surface of the core member adjacent to the diaphragm, each cavity being aligned with one of the conductive rings.

20. A device as defined in claim 19, wherein the displacement cavities are of equal circular dimension.

21. A device as defined in claim 19, wherein the core includes means for generating a biasing magnetic field having a continuously oscillating strength selected to provide a biasing force on the diaphragm responsive to the magnetic field developed within the at least one conductive coil to displace the diaphragm to a baseline displacement and tension.

28. A method for emitting a broad frequency range including ultrasonic frequencies, yet having a capacity for relatively large diaphragm displacement as compared to lesser movement of a typical electrostatic diaphragm movement, the method comprising the steps of:

(a) providing a continuously variable magnetic field adjacent a supporting core member;

(b) maintaining a movable diaphragm having at least one conductive ring thereon in stretched configuration along the core member and displaced a short separation distance from the core member to allow an intended range of orthogonal displacement of the diaphragm with respect to the core member and within a strong portion of the variable magnetic field; and

(c) inductively coupling the variable current flow within the at least one coil with the at least one ring for developing a second magnetic field which variably interacts with the first magnetic field to repel the diaphragm at a desired frequency for development of a series of compression waves which may be adjusted to include an ultrasonic frequency range.

29. A method as defined in claim 28, wherein the step of supplying the continuously variable magnetic field at the core comprises developing an alternating current within conductive coils coupled to the core to generate a resulting variable magnetic field for repelling the diaphragm, said alternating current providing a momentary relaxation period to allow the diaphragm to resume a rest position which is slightly biased in tension.

30. A method as defined in claim 29, wherein the supplying step comprises developing the alternating current at a frequency corresponding to a frequency range within the ultrasonic bandwidth.

31. A method as defined in claim 29, wherein the alternating current includes a fixed carrier frequency portion within the ultrasonic frequency range, plus a sonic frequency modulated with the carrier frequency to generate at least two ultrasonic frequencies whose difference in value corresponds to the sonic frequency.

32. A method as defined in claim 31, further comprising the step of applying the fixed carrier frequency to bias the diaphragm to a displacement distance from the core member wherein the diaphragm is in tension, but capable of further displacement in response to the two ultrasonic frequencies to generate compression waves within the ultrasonic frequency range which interfere in air to develop a sonic output.