| 摘要 |
PROBLEM TO BE SOLVED: To solve such a problem that a conventional structure of a planar speaker in which a plurality of small magnet chips are arranged in a checkerboard pattern and a circuit is established along each small magnet chip on a diaphragm membrane in a spiral pattern or in a zigzag pattern, aggravates partial split vibration of the diaphragm membrane. SOLUTION: A plurality of annular magnets are arranged on a planar yoke face at a prescribed interval concentrically in such a way that the polarity is sequentially changed. A conductive circuit is formed in spiral on the diaphragm membrane close to an annular magnet group so as to be perpendicular to a direction of the magnetic flux formed by the annular magnet group. The conductive circuit is established to be circulated along an outer circumferential side and an inner circumferential side of each annular magnet, and every time a direction of horizontal magnetic flux of the annular magnet is inverted, the circulation direction is inverted. The conductive circuit reaches an output terminal by repeating the spiral circulation on an opposite side (back side) of the diaphragm membrane toward the outer circumference side similar to the circuit on the front side via a through-hole located in the vicinity of the center of the annular magnets at the innermost circumference. Combination of the annular magnet and the spiral conductive circuit can form the diaphragm membrane with a physically high holding power of a planar shape. COPYRIGHT: (C)2007,JPO&INPIT
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