| 摘要 |
PURPOSE:To achieve the improvement in the accuracy and stability of servo control for playback head by applying AGC to the reproduction signal and so arranging the apparatus that this AGC does not respond to the vibration frequency of the playback head. CONSTITUTION:The detection signal Sd showing a level of an FM signal Sf from a detection circuit 24 is supplied to a BPF 27 to be removed of the component of the frequency omega of the vibrations of a playback head, whereby it is made to the signal Sb which has only the level change caused by the contact vibrations with heads 1A, 1B and tape 7. This signal is supplied as its gain control signal to an amplifier 21. Hence, AGC is applied to the signal Sf from the amplifier 21 by the signal Sb, thus the signal Sf contains no more level variations owing to the contact state of the heads and tape. However, the component of the frequency omega is not included in the signal Sb and therefore the signal from the amplifier 21 is changed only of its level by the vibrations of the heads 1A, 1B. Thereby the accuracy and stability of the servo control may be improved. |
