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Magnetically shielded electromagnetic acoustic transducer

  • US 4,956,868 A
  • Filed: 10/26/1989
  • Issued: 09/11/1990
  • Est. Priority Date: 10/26/1989
  • Status: Expired due to Term
First Claim
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1. A magnetically shielded electromagnetic acoustic transducer comprising:

  • an acoustic diaphragm;

    a magnetic armature;

    mechanical drive connection means interconnecting the armature and the diaphragm;

    an electromagnetic coil disposed in encompassing relation to a portion of the armature;

    magnetic connection means linking the electromagnet coil and the armature in a complete magnetic circit having a plane of symmetry across which no appreciable magnetic flux flows;

    and a magnetic shield encompassing the diaphragm, the armature, the coil, and both connection means,the magnetic shield comprising two generally cup-shaped casing halves of high magnetic permeability joined together along a joint plane closely adjacent to and parallel to said plane of symmetry.

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