| 摘要 |
PURPOSE:To improve electroacoustic transducing efficiency, by constituting a magnetic circuit with an odd-shaped magnet which is made of a worked plate and has a radial magnetic anisotropy coinciding with an extended direction. CONSTITUTION:The electroacoustic transducer used for a telephone set, etc., is constituted of an annular member 10 made of a permanent magnet, cylindrical pole piece 13, voice coil 15, armature 12 supported by a diaphragm sheet 14, and an Al-made diaphragm 11 supported by the armature 12 as shown in the diagram. The annular member 10 is manufactured in such a way that a straight pipe is formed of an Fe-Cr-Co magnet alloy and magnetic field treatment is performed on the pipe in an extended direction and an intense odd-shaping work accompanied with pipe expansion or diameter expansion or reduction at one end is performed, and then, aging treatment is performed on the worked product. The annular member 10 constituted in such a way maintains the radial magnetism anisotropy and attains an excellent magnetic characteristic. |
