| 摘要 |
PURPOSE:To retrieve a track securely by feeding a reader stepwise in a radius direction according to a difference between a retrieved address and a current address and then by making one-track jumps up to the retrieved address. CONSTITUTION:From the output of a main beam detector 15, an address detecting circuit 46 detects an address signal and a step-number determining circuit 50 determines the number of steps required to move a head in a disk radius direction according to a difference between a current address and a desired retrieved address, so that a step motor 27 turns as much as the number of steps through a step motor controlling circuit 42. Then, jump pulses are generated according to the difference between an address detected again and the retrieved address to drive a rotary mirror 12, thereby permitting the head to approach to a targeted track, one by one. |
