| 摘要 |
PURPOSE:To attain the stabilization of a phase synchronization circuit even if a control signal is supplied under conditions different from the optimum condition because of different specifications of a controller by providing additionally an output detecting circuit, a seek detecting circuit and a load detecting circuit. CONSTITUTION:When a head load signal (d) is inputted, a time until a magnetic head contacts a disc is formed by the load detecting circuit 3, a reference clock (b) is inputted to the phase synchronization circuit 7 and a reading signal (a) is inputted to the phase synchronization circuit 7 after the magnetic head contacts the disc. When a step signal (e) is inputted, the time until the vibration of the magnetic head is settled is formed by the seek detecting circuit 4, and the reading signal (a) is inputted to the phase synchronization circuit 7 after the step operation is finished. The output detecting circuit 2 prevents a wrong reading signal (a) from being inputted to the phase synchronization circuit 7 when an output falls down because of any cause. As a result, the phase synchronization circuit is operated stably. |
