| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent a large disturbance in tracking by executing control only when the speed servo in a case where a channel head clog arises and executing the control with ATF and speed servo when the tracking changes transiently. SOLUTION: An input signal is made a pilot signal by an RF circuit 52 and a pilot extraction circuit 53. This pilot signal enters a detection circuit 55. The signal of an ATF detecting circuit 54 generates a sampling pulse by timing generation 58 to take the signal from this detecting circuit 55 into S/H 56, 57. Next, the pilot signal level is compared by subtraction 59 and integration 60, and the ATF tracking error signal is obtd. A controller circuit 67 judges the occurrence of the head clog by the signal of a timing generating circuit 58 and turns off a switch 61. A driving circuit 66 is controlled by the signal of a speed error circuit 65. The switch 61 is turned on and the control is executed by the ATF and the speed error signal when the tracking changes transiently. Thereby, a large disturbance in the tracking is prevented.</p> |
