Planar diaphragm transducer with improved magnetic circuit
Patent 4471172 Issued on September 11, 1984. Estimated Expiration Date: 
March 1, 2002. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
March 1, 2002. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3674946 3829623 3833771 3922502 3922503 Composite type acoustic transducer Patent #: 4242541 InventorAssigneeApplicationNo. 06/353846 filed on 03/01/1982US Classes:381/427, Metal381/412, Magnetic circuit381/431FlatExaminersPrimary: Rubinson, Gene Z.Assistant: Schroeder, L. C. Attorney, Agent or FirmInternational ClassesH04R 9/00 (20060101)H04R 9/04 (20060101) AbstractA planar diaphragm type magnetic transducer with magnetic circuit wherein the magnet strips on the soft iron plate and confronting the diaphragm are arranged in a sequence south, north, north, south, south, north, north, south, et seq. The magnet strips are spaced across the transducer and the metal plates on which the magnet strips lie are apertured to make the plates acoustically transparent. Conductors are grouped in runs on the diaphragm opposite alternate pairs of magnet strips which have magnetic poles of opposite polarity at their front faces.Other References
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