| 摘要 |
PURPOSE:To avoid malfunction of a rotation servo due to the occurence of noises by supressing a lower frequency component than a carrier frequency corresponding to a synchronizing signal of frequency-modulated high frequency signal, which is reproduced at the time of de-tracking. CONSTITUTION:A reproduction signal read out from a disk by means of a light head is supplied to an input terminal 37, and added to an amplifier 10. Gains of the amplifier 10 become larger and has a characteristic of a high-band compensation, when a transistor 35 is turned on and when a trap circuit of 4.5- 5MHz consisting of a resistance 18, a coil 29 and a capacitor 30 is held in a circuit arrangement. Since a control signal at a low level is added from a terminal 33 at the time of a normal reproduction, the transistor 35 is turned off, which keeps the trap circuit still in recess, and gains of the amplifier 10 become smaller. As a result, a reproduction signal of the light head is band-controlled through a suppressing trap circuit <=2MHz consisting of a BPF38, capacitors 21 and 23 and coils 22 and 24.
|
