| 摘要 |
PURPOSE:To avoid deterioration of the acceleration of a recording disk by monitoring the frequency of a read signal and inhibiting the dropout compensa tion while said frequency is kept at a level lower than the prescribed value. CONSTITUTION:The dropout detecting signal is amplified and wave-detected by a buffer amplifier 7 and a wave detecting circuit 8. The wave detection output is kept at a level H while the frequency of a read signal is low. Then the dropout detecting signal is set at a level L when the frequency of the read signal exceeds the working frequency of a dropout detecting part 2. Thus said wave detection output is also set at a level L and supplied to the base of a transistor 9. The transistor 9 conducts when the wave detection output is kept at a level H, and the collector of the transistor 9 is set at a level approximately equal to the earth voltage level (L). Then a level L is supplied to a correction command generating part 6 from the collector output. The part 6 inhibits the supply of the switch signal to a switch 4 when the collector output of a level L is supplied to a built-in gate circuit. |
