Magnetic film ultrasonic emitter

• US 6,151,398 A
• Filed: 01/13/1998
• Issued: 11/21/2000
• Est. Priority Date: 01/13/1998
• Status: Expired due to Term

• 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): DABNEY, PHYLESHA LARVINIA
• Application Number:
  US09/006,134
• Time in Patent Office: 1,043 Days
• Field of Search: 381/77, 381/400, 381/401, 381/192, 381/396, 367/140, 367/132, 367/133, 367/153
• US Class Current: 381/77
• 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 first magnetic field adjacent the core member and a movable diaphragm stretched along the core member and displaced a short separation distance within a strong portion of the magnetic field. At least one, low mass, planar, conductive coil is disposed on the movable diaphragm and includes first and second contacts for enabling current flow through the coil. A variable current flow to the at least one coil provides a second magnetic field which variably interacts with the first magnetic field to attract and 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.

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

a movable diaphragm extending 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 first magnetic field;

at least one, low mass, planar, conductive coil disposed on the movable diaphragm and including first and second contacts for enabling current flow through opposing ends of the coil; and

means for supplying variable current flow to the at least one coil for developing a second magnetic field which variably interacts with the first magnetic field to attract and 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.

2. A device as defined in claim 1, wherein the core member comprises a permanent magnet.

3. A device as defined in claim 2, wherein the permanent magnet comprises a rigid plate of magnetic material 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 magnetic field along a surface of the plate most adjacent the movable diaphragm.

5. A device as defined in claim 2, wherein the permanent magnet comprises a flexible magnetic 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 opposing conductive coil.

7. A device as defined in claim 6, wherein the at least one opposing conductive coil is positioned on the rigid plate in a location which is juxtaposed to the at least one conductive coil on the movable diaphragm to enable the at least one conductive coil and at least one opposing conductive coil to cause respective magnetic fields from each coil 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 and the at least one opposing conductive coil to provide such that each coil generates a variable magnetic field which is capable of enhancing repulsion and attraction arising between the respective coils.

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

10. A device as defined in claim 9, wherein the film comprises a polymer having isotropic 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 film includes width and length dimensions including at least a two inch diameter.

13. A device as defined in claim 1, wherein the coil is deposited on the diaphragm as a conductive element, said first contact being positioned on one side of the diaphragm and the second contact being positioned on an opposing side of the diaphragm.

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

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

16. A device as defined in claim 15, wherein the plurality of conductive coils 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 at least one conductive coil.

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

19. A device as defined in claim 18, wherein the support perimeter for isolating the coils 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 coils.

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 comprises a permanent magnet having a magnetic field strength selected to provide a biasing force on the diaphragm based on the magnetic field developed within the at least one conductive coil.

22. A device as defined in claim 1, wherein the core comprises an electromagnetic composition and includes means for supplying a voltage for developing an electromagnetic force at the core which is operable with respect to the at least one conductive coil to develop the desired diaphragm displacement.

23. A device as defined in claim 22, wherein a plurality of conductive coils 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 first magnetic field adjacent the core comprises an opposing at least one conductive coil positioned on the core adjacent the at least one conductive coil of the diaphragm.

25. A device as defined in claim 1, comprising a plurality of conductive coils on the diaphragm and a corresponding plurality of conductive coils juxtaposed to the conductive coils on an opposing side of the diaphragm.

26. A device as defined in claim 24, wherein the means for providing the first magnetic field comprises a variable current flow to the at least one coil at the core in a phase inverted relationship with the variable current applied to develop the second magnetic field to thereby enhance the attraction and repulsion of the diaphragm for development of a series of compression waves which may be adjusted to include the ultrasonic frequency range.

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

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 first magnetic field adjacent a supporting core member;

(b) applying at least one conductive coil to a movable diaphragm extending 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 first magnetic field; and

(c) supplying variable current flow to the at least one coil for developing a second magnetic field which variably interacts with the first magnetic field to attract and 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.