Rotation control apparatus operating with a sync signal having variable intervals

摘要

A rotation control apparatus which can maintain an accurate rotating state even in a high density optical disk (DVD) having a structure such that parts of the sync signal are recorded at an interval different from that of the other sync signal parts. The apparatus has: a unit period signal generator for generating a period signal of a unit period; a pre-pit detector for detecting a pre-pit from the DVD; a phase difference detector for detecting a phase difference between the detection timing of the pre-pit and the unit period signal; and a holding circuit for holding the phase difference detected. The rotation of the DVD is controlled on the basis of the phase difference held at the holding circuit.