Electromagnetic transducer and portable communication device
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsSawako Usuki, Shuji Saiki
Life of this patent
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Abstract
An electromagnetic transducer, includes: a first diaphragm disposed in a vibratile manner; a second diaphragm provided in a central portion of the first diaphragm, the second diaphragm being formed of a magnetic material; a yoke disposed in a position opposing the first diaphragm; a center pole provided on a face of the yoke that opposes the first diaphragm; a coil substantially surrounding the center pole; a magnet substantially surrounding the coil; and a thin magnetic plate provided between the magnet and the first diaphragm, an inner periphery of the thin magnetic plate being in overlapping relation to an outer periphery of the second diaphragm.
Claims23
An electromagnetic transducer comprising:
- a first diaphragm disposed in a vibratile manner;
- a second diaphragm in a central portion of the first diaphragm and formed of a magnetic material;
- a yoke disposed in a position opposing the first diaphragm;
- a center pole on a face of the yoke that opposes the first diaphragm;
- a coil substantially surrounding the center pole;
- a magnet substantially surrounding the coil;
- and
- a thin magnetic plate between the magnet and the first diaphragm and having:
- (a) an outer peripheral edge, and
- (b) an inner periphery in overlapping relation to an outer periphery of the second diaphragm,
- wherein the outer peripheral edge of the thin magnetic plate substantially coincides with a neutral point at which directions of magnetic flux vectors occurring on a surface of the magnet become diversified so that some of the magnetic flux vectors traverse toward the center pole while others traverse toward an outer periphery of the magnet.
An electromagnetic transducer comprising:
- a first diaphragm disposed in a vibratile manner;
- a second diaphragm provided in a central portion of the first diaphragm, the second diaphragm being formed of a magnetic material;
- a yoke disposed in a position opposing the first diaphragm;
- a center pole provided on a face of the yoke that opposes the first diaphragm;
- a coil substantially surrounding the center pole;
- a magnet substantially surrounding the coil;
- and
- a thin magnetic plate provided between the magnet and the first diaphragm, an inner periphery of the thin magnetic plate being in overlapping relation to an outer periphery of the second diaphragm,
- wherein the magnet includes a recessed portion on a face thereof opposing the first diaphragm at an inner periphery thereof, the thin magnetic plate being snugly received by the recessed portion.
Dependencies are inferred from the claim text.