| 摘要 |
PURPOSE:To lock the phase quickly to the prescribed phase of a reference signal and to ensure the stable action by using the output of a common phase error detecting means which produces an error signal corresponding to the phase difference of both signals to drive the course and fine adjusting means. CONSTITUTION:A spindle servo system includes a phase error detector PD1 having a wide dynamic range and low detecting sensitivity, a switch 11 which selects the output of the PD1 and the output of a servo amplifier 7 of a tangential servo system, and amplifiers 8 and 9 which amplify the error signal selected by the switch 11. The revolution of a spindle motor is controlled by a drive amplifier 9 at the final stage. The tangential servo system contains a PD2 which has a narrow dynamic range and a high level of detecting sensitivity. The error output produced by the PD2 is supplied to the amplifier 7 via a buffer 4 and a loop switch 6. The output of the amplifier 7 is supplied to a drive amplifier 10 via a DC cutting capacitor C2 and turned into a tangential mirror driving signal. |
