| 摘要 |
PROBLEM TO BE SOLVED: To provide a rotating speed detector which is small-sized and capable of detecting even a low speed. SOLUTION: A circuit part is packaged with a coil block B formed by winding a detecting coil 2 on a coil bobbin 3 on a circuit board 5. The circuit board 5 is stored with the coil block B positioned at the bottom in a housing 6 shaped like a bottomed cylinder by synthetic resin. A mount 7 is fitted to an open end of the housing 6. Thus, the detecting coil 2 is driven with high frequency current to generate a high frequency magnetic field, and a signal corresponding to the projecting and recessed part 1a is taken according to a difference in amount of an eddy current generated in the surface of a rotor 1 by the high frequency magnetic field, so that a small-sized detecting coil 2 with a diameter and a length of about several mm is provided. Accordingly, it is possible to provide a rotating speed detector which is small-sized and capable of detecting even a low speed.
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