| 摘要 |
<p>PURPOSE:To apply tracking control accurately over the entire range of tracking servo by changing the speed of a rotating body for a prescribed quantity for a prescribed time from the operation start. CONSTITUTION:A speed control means 54 is provided in parallel with a switch 55 and a DC power supply provided between a sample-and-hold circuit 32 and an adder 50 and consists of a DC power supply 56 whose potential is set within the tracking servo locking range, a switch 57 changing over DC power supplies 56, 57, a flip-flop circuit 58 generating a signal changing over the switches 55, 57, and a counter 59 reset by a signal S2, generating a signal '1' when the 2nd sampling pulse SP2 is detected for a specified number of times, e.g., twice or 4 times during one revolution of a drum and setting the flip-flop circuit 58. The switches 55 and 57 are thrown to the position of a contact (a) at the leading of the tracking servo and thrown to the position of a contact (b) when the 2nd sampling pulse SP2 is detected twice or 4 times during one revolution of the drum and the flip-flop circuit 58 is set.</p> |
