Clock signal generating device and clock signal generating method

Abstract

A clock signal generating apparatus and method in which data recorded in a plurality of tracks and clock marks recorded at equal angular spaces at different radial distances on a rotating disk are reproduced by a reproducing head from the disk and a clock signal is generated in synchronism with the clock marks reproduced by the reproducing head by means of a discriminating circuit for detecting a synchronous state between the generated clock signal and the reproduced clock marks, a circuit for causing oscillation of the reproducing head in a radial direction of the disk over a plurality of tracks when the synchronous state discriminating circuit determines that the clock signal is not synchronous with the clock marks, and a phase-locked loop circuit for generating the clock signal in synchronism with the clock marks reproduced from the disk while the reproducing head is oscillated over the plurality of tracks by synchronizing on the clock marks reproduced at a variety of different radial positions on the disk as the disk is rotated.