| 摘要 |
PURPOSE:To prevent malfunctions of tracking control, by separating a tracking location detecting signal into a noise component and a control signal, by holding, during a period where a noise occurs, the level just before the noise, and by using the level as the control signal. CONSTITUTION:Only a high frequency component (b) is fetched from a signal (a) of a tracking location detecting circuit 6 by an HPF9, and noise are detected at the 1st and 2nd threshold circuits 10 and 11, and then, corresponding pulses (c) and (d) are generated. The opening/closing control of a switch circuit 13 is performed by a signal (e) obtained from an adder 12. The switch circuit is opened only when the signal (e) is at 0 level, and the circuit 13 supplies the location detect signal (a) to a mirror driving circuit 7. Moreover, during the period where the signal (e) is at 1 level, the level of the signal (a) just before the switch circuit 13 is opened is held by a previous value holding circuit 14 and the level is supplied to the driving circuit 7 as a false track location detecting signal. |
