| 摘要 |
PURPOSE:To stabilize tracking without an LPF by adding a tracking error signal obtained by a wobbling method to a signal passed through a delay circuit for delay one fourth as long as a wobbling period. CONSTITUTION:The output of a BPF15 in which a wobbling frequency component SW' processed by amplitude and phase modulation is inputted to an ana- log multiplier 20 together with a signal S from a wobbling signal generating circuit 12. To the analog multiplier 20, a delay circuit 21 is connected, and the output of the delay circuit 21 and that of the analog multiplier 20 are added and connected to a driving circuit for tracking control through an amplifier 18. The delay period of the delay circuit is set one fourth as long as the period of a signal S. Thus, a tracking control signal with less phase rotation is obtained without increasing a wobbling frequency. |
