| 摘要 |
PURPOSE:To facilitate the locking of a PLL without reference to whether a used disk is a CLV or CAV type, by simply increasing or decreasing a rotational frequency in response to a disk rotation start command. CONSTITUTION:A control circuit 10 connects a switch 12 to neither contact before a start signal is inputted. Once the start signal is inputted, the switch 12 is connected to a driving signal generating circuit 13 to simply increase the rotational frequency of a motor 2. When its final rotational frequency is st much higher than the rotational speed of a disk at the innermost circumference, the output signal of a pickup passes the lock range of a playback clock extracting PLL at any radius position without fail, so that the PLL4 is locked without fail. At this time, a detection signal is inputted from a detecting circuit 5 to the control circuit 10 and the switch 12 is changed over to the side of a phase comparator 9 to perform phase control operation thereafter by a reference clock and a playback clock. |
