| 摘要 |
PURPOSE:To eliminate the disorder of a tracking error signal and prevent a pickup from operating abnormally by inhibiting a sample holding means which generates a signal for generating the tracking error signal from performing sampling operation when one of a couple of arithmetic outputs is absent. CONSTITUTION:An RF signal outputted by an inverting amplifier 4 is delayed through a delay circuit 14 composed of a delay line, etc., and supplied to a sampling pulse generating circuit 6. At the same time, the RF signal from the inverting amplifier 4 is supplied to a dropout detecting circuit 15. The dropout detecting circuit 15 compares, for example, the envelope component of the RF signal and compares it with a specific reference voltage to generate a high-level dropout detection signal when the signal level of th RF signal drops below a specific level. The output of this dropout detecting circuit 15 is applied to the base of a transistor Q through a resistance R14. |
