ROTATIONAL SPEED DETECTION DEVICE

摘要

PURPOSE:To improve the precision of FG signals by canceling rotational periodic components and their higher harmonic components contained in each FG signal caused by inaccurate assemblies and eccentricities while a magnetic tape is running. CONSTITUTION:A rotational cycle detecting circuit 2 detects the rotational cycle of a rotating body. An FG cycle error is detected by taking the difference between the rotational cycle and the value divided by the number of pulses of the FG signal as an FG cycle error and a comb line filter consisting delay circuits 71 to 76 extracts one rotational components of the rotating body and their higher harmonic components from the error signal. Having taken the ratio between the signal and the rotational cycle and stored in the means 71 to 76, the FG cycle is compensated by multiplying the detected rotational cycle. Thus, compensation corresponding to the rotational cycle of the rotating body is accomplished.