Apparatus for detecting rotating speed of an object.

摘要

In an apparatus for detecting a rotating speed of a rotating object, in which a pulse train having a frequency proportional to the rotating speed is generated and the rotating speed is detected by detecting the period of the pulse train, the period detection results are over-sampled to form a recursive filter having a peak at the frequency where the frequency characteristic of the period detecting operation becomes zero. As the result, the frequency characteristic of the apparatus as a whole does not have a peak. The phase delay due to the period detecting operation is reduced.