Patent ID: 6212143
Filing Date: 2001-04-03
Classification: G11B

Abstract:
A spindle motor control system controlling a spindle motor for rotating an optical disk at a constant linear velocity for recording/reproducing data, said system comprising:a clock extracting unit which extracts a clock component from the reproduction data;a constant linear velocity control unit that controls the spindle motor by generating a first drive signal in accordance with the extracted clock component to thereby rotate the optical disk in a constant linear velocity mode;a rotational velocity detecting unit that detects a value corresponding to a current rotational velocity of the spindle motor;a constant angular velocity control unit that controls the spindle motor by generating a second drive signal in accordance with the current rotational velocity of the spindle motor detected by said rotational velocity detecting unit to thereby rotate the optical disk in a constant angular velocity mode; anda clock period supervisory unit that judges whether or not the clock component extracted from the reproduced data is within a given range in which constant linear velocity control can be stably performed, and that switches control of the spindle motor between said constant linear velocity control unit and said constant angular velocity control unit depending on whether said clock component extracted from the reproduced signal is within said given range.