| 摘要 |
PROBLEM TO BE SOLVED: To provide an inexpensive fan rotation detection device for detecting accurately and instantly an abnormality such as decline of a rotational frequency or stop of a cooling fan. SOLUTION: A loop antenna 15 is mounted on a fan unit 11 including a fan 13 connected directly to an electric motor and driven rotatively. A change of a leakage magnetic flux of the electric motor is detected by the antenna. The frequency of a detected detection signal is measured by an oscilloscope 16. The rotation state of the fan can be known by monitoring the frequency, and the cooling state in the device provided with the fan unit can be grasped. COPYRIGHT: (C)2006,JPO&NCIPI
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