| 简介 |
PROBLEM TO BE SOLVED : To provide an external magnetic type magnetic circuit unit for a speaker, in which even if a rare earth magnet is used, the magnet is hard to be rusted, and a magnetic gap part having high accuracy and a high magnetic field is provided. SOLUTION : The external magnetic type magnetic circuit for a speaker includes : a yoke 31 in which a center pole 35 is formed in the center part of a ring-shaped bottom plate 34; a ring-shaped magnet part 32 surrounding the center pole 35; and a ring-shaped top plate 33 surrounding the center pole 35 and having a center opening part peripheral surface for forming the magnetic gap part 36 between itself and the upper end side peripheral surface of the center pole 35 with the magnet part 32 held and fixed between itself and a bottom plate 34. The magnet part 32 is formed of a rare earth magnetic material, at least the peripheral side thereof comprises a ring-shaped magnet 38 covered with a resin component 37, and the resin component 37 is formed of a resin material containing an oxide based magnet material. COPYRIGHT : (C)2013, JPO&INPIT |
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