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1. WO1984000460 - TRANSDUCTEUR ELECTROMAGNETIQUE-ACOUSTIQUE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

THE CLAIMS defining the invention are as follows:

1. An electromagnetic acoustic transducer comprising a diaphragm having on at least one face an audio-frequency current conductor, the conductor being arranged in a waveform pattern to ' divide the diaphragm into a plurality of acoustically rigid zones and define current paths along the sides of the zones, an array of magnets so arranged that magnetic fields produced thereby interact with the current paths along the sides of the zones whereby during passage of an audio-frequency current through the conductor interaction between the audio-frequency current passing along the current paths and the respective magnetic fields causes vibration of the diaphragm.

2. A transducer as claimed in claim 1 wherein the waveform is of castellated formation.

3. A transducer as claimed in claim 1 wherein the waveform is of sawtooth formation.

4. A transducer as claimed in any one of the precedin claims wherein the zones are of rectangular configuration.

5. A transducer as claimed in any one of the precedin claims wherein there is an audio— requency current conductor on each face of the diaphragm, the conductors being so arranged that each zone has at least one current path along each side thereof.

6. A transducer as claimed in any one of the precedin claims wherein the magnets are permanent magnets and are attached to a backing member of magnetic material, the backing member being acoustically transparent.

7. A transducer as claimed in any one of the preceding claims wherein the diaphragm is of flexible material, the zones being rendered acoustically rigid by tension applied to the diaphragm.

8. A transducer as claimed in claim 7 wherein the diaphragm is secured at its periphery to a peripheral frame, the peripheral frame being formed integral with or secured to the backing member.

9. A transducer as claimed in any one of claims 1 to 6 wherein the diaphragm is of flexible material, the zones being rendered acoustically rigid by rigidising means formed in the diaphragm.

10. A transducer as claimed in claim 9 wherein the rigidising means comprises a compound formation in the diaphragm at each zone.

11. A transducer as claimed in claim 10 wherein the compound formation comprises a hemispherical dome merged transitionally with the sides of the respective zone.

12. A transducer as claimed in claim 10 wherein the compound formation comprises a hollow cone merged transitionally with the sides of the respective zone.

13. A transducer as claimed in claim 10 wherein the compound formation comprises a hollow pyramid merged transitionally with the sides of the respective zone.

14. A transducer as claimed in any one of claims 1 to 6 wherein the diaphragm is formed of substantially rigid material.

-- WIPO 15 A transducer as claimed in any one of the preceding claims wherein the pole faces of the magnets are of configuration which is geometrically similar to the configuration of the zones.

16. A transducer as claimed in any one of the precedin claims wherein there is one said permanent magnet corresponding to each zone on the diaphragm, the pole faces o adjacent magnets being of opposite polarity.

17. A transducer as claimed in any one of claims 1 to 15 wherein there is one said permanent magnet corresponding to each alternate zone on the diaphragm, there being pol shoes corresponding to the other zones, the pole faces o the magnets being of the same polarity.

18. A transducer as claimed in any one of the claims 9 t 17 wherein the diaphragm is supported within its perimete by a plurality of resilient support members which permi said vibration of the diaphragm.

19. A transducer as claimed in claim 18 wherein eac resilient support member is attached to the diaphragm a the apex of a respective compound formation in th diaphragm.

20. An electromechanical acoustic transducer substantiall as herein described with reference to the accompanyin drawings.

s y, WIPO