| 摘要 |
PURPOSE:To control the information reading position so as to be moved accurately in a prescribed line speed in the tangential direction of a track by extracting track address information from a pickup output and detecting accurately a track on which the information is read. CONSTITUTION:A pickup 60 reads the information recorded on the track of the disc 10, the output is fed to a waveform shaping circuit 72 through an amplifier circuit 71, the track address information and a signal data are demodulated from the output of the circuit 72 by using a clock from the phase locked loop 73, the synchronism information from a detection circuit 74 and an address mark, and the track address information and a reproducing signal are extracted separately by the processing circuit 76. The output of an operation control circuit 80 decides the frequency dividing ratio N of a frequency division circuit 42 of a reference clock generating circuit 40, the frequency of the reference clock is corresponded to the track address at that time and fed to a phase comparator circuit 51 of a motor control circuit 50 so as to control the motor 20 through a servo circuit 52. |
