| 摘要 |
PROBLEM TO BE SOLVED: To provide a small-sized, high-output, and low-cogging torque direct- current motor, using thin arc-shaped rare-earth magnets with a maximum thickness of less than 1 mm for use in audio video equipment with its starting voltage and starting current reduced, so that the motor runs with accuracy. SOLUTION: Arc-shaped rare-earth magnets 1, less than 1 mm in maximum thickness, formed by compression-molding rare-earth-iron quenching-solidified thin pieces, together with binder are pressed against and secured on a magnetically soft frame 2, and both ends 11 in the circumferential direction without a back yoke for obtaining a permanent magnet field system type, small-sized direct-current motor. The arc-shaped rear-earth magnets formed by compression molding, containing more rare-earth-iron quenching-solidified thin pieces, have such a property where remnant magnetic flux density Br and coercive force HC further increase simultaneously as a function of magnetization fields, and obtains balanced demagnetizing curves, even in an saturated magnetization state.
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