| 摘要 |
PURPOSE:To prevent the turbulence caused by a flaw of a disk of tracking control by holding a low band component of tracking error signal of an opening contact, when a tracking servo-circuit is opened, and leading it exactly into a usual servo-state, when the servo-circuit is closed thereafter. CONSTITUTION:The ordinary servo-system of a tracking servo-circuit of an optical pickup is constituted of the first and the second phase compensating circuits 1, 2 for inputting an error signal TR, driver amplifying circuit 3, and a switching means 5 provided between the circuits 1, 2, and the output of the circuit 3 is supplied to a tracking coil 4. Also, the level of an envelope signal of an HF signal from an information sensor is detected by a level detecting circuit 8, and the signal of a low level period from the circuit 8 is detected by a level detecting means 11. By such a signal, the means 5 is opened, and the error signal of an opening contact is held in the capacitor C1 of a holding means 6. When the servo-system is closed thereafter, a usual servo-state is obtained exactly. |
