| 摘要 |
PURPOSE:To eliminate the effect of the uneven tape travelling speed which arises in a recording/reproduction system, by comparing the frequency corresponding to the travelling speed of a magnetic tape with the reference frequency. CONSTITUTION:The phase of the speed signal passed through a variable delay element 6 follows the phase fluctuation of the speed fluctuation during the recording, and the phase of the speed signal from the element 6 coincides with the reference signal during the reproduction respectively by a speed detecting head 7 and a speed detecting circuit 8. The clock signal supplied from a VCO12 contains no wow and flutter component of the tape travelling speed. The output of the detector 8 is supplied to a phase comparator 18 to be compared with the signal sent from a reference oscillator 16 in terms of the phase. Then the error signal is extracted. This signal controls the number of rotations of a capstan 21 via a DC amplifier 19 and a motor driving circuit 20. The travelling speed of a tape 1 is controlled based on the oscillation 16. Thus no difference of frequency is caused between the speed signal and the reference signal. |
