| 摘要 |
PURPOSE:To enable both magnetic poles of coils to be magnetized with sufficient strength, by providing the end surface of a cylindrical core with grooves, and by fitting a coil for magnetizing a driving magnetic pole and a coil for magnetizing a magnetic pole for detecting rotational frequency, to be put together partially in a plane state. CONSTITUTION:The end surface of a cylindrical core 1 made of magnetic material is provided with circumferential grooves 8, and is divided into an inner peripheral core 2 and an outer peripheral core 3. Radial grooves 6 are formed on the inner peripheral core 2, and an exciting coil 10 for magnetizing a driving magnetic pole is fitted in the grooves 6. Another radial grooves 9 are formed on the outer peripheral core 3, and an exciting coil 11 for magnetizing a magnetic pole for detecting rotational frequency is fitted in the groves 9. Then, both the exciting coils 10 and 11 are arranged to be partially put together in a plane state. By this method, the driving magnetic pole and the magnetic pole for detecting rotational frequency can be sufficiently magnetized, and driving torque and detection signal can be increased.
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