| 摘要 |
PURPOSE:To operate surely a servo loop by retarding the on-timing of a tracking servo loop switch under a prescribed condition and opening the servo loop when the rotation of a disc is made stable. CONSTITUTION:A rotation detecting sensor 30 is fitted to a disc motor 12 and its output signal is inputted to a number of revolution detecting circuit 31. Then a control signal to turn on a switch 22 is obtained from the number of revolution detecting circuit 31 not until the rotating speed of the disc motor 12 reaches a prescribed speed. Thus, the tracking servo loop comprising a tracking control signal generating circuit 21, a switch 22, and a tracking coil drive circuit 23 is formed without fail after the rotating speed of the disc motor 12 reaches a prescribed speed. Further, a conventional switch control signal from the focus control circuit 24 is not required. Thus, the pull-in operation of the tracking servo is made stable and the reliability of the device is attained. Further, a misunderstanding such as a fault is avoided. |
