| 摘要 |
PURPOSE:To make always stable tracking servo possible, by stopping the movement of the output voltage of a voltage generating circuit and holding the stopped condition when a disk is mounted on a player and the output level of multiplying circuit becomes almost equal to that of the 2nd photodetector. CONSTITUTION:When the counted value of a counter 35 varies from (n) to (n+1), the output S3 of a voltage comparing circuit 33 varies from a low level L to a high level H and counting of a clock CK at the counter 35 is stopped. Then the data of the counter 35 is recorded and held in a memory 36 and the peak value of the output X.Ie of a multiplying circuit 30 and the peak value of the output If of a photodetector 22F are maintained at almost the same values. When the output S3 of the voltage comparing circuit 33 becomes high in level, a switch 31 is turned on and a tracking error signal Et which is the output of a subtracting circuit 23 is applied to a movable coil 25 of a tracking driving means through an amplifier circuit 24 and, as a result, tracking servo is started. |
