Rotation control device for information recording disc

A rotation control device for rotating a disc on which an information signal and a sync signal are recorded, comprising:

• a motor for causing the disc into rotation;
• rotation signal generator means for generating a rotation signal having a frequency which is proportional to a rotation speed of said motor;
• first reference signal generator means for generating a first reference signal which is identical in frequency with the sync signal;
• first phase comparator means for generating a first difference signal responsive to a phase difference between the sync signal read out of the disc and the first reference signal;
• second reference signal generator means for generating a second reference signal while the motor rotates the disc for reproducing the sync signal having said frequency out of the disc, said second reference signal being identical in frequency with the rotation signal output from the rotation signal generator means;
• second phase comparator means for generating a second difference signal responsive to a phase difference between the rotation signal output from the rotation signal generator means and the second reference signal;
• operator means for performing a predetermined operation with the first and second difference signals to generate a signal as a result of the operation;
• phase compensator means for compensating a phase of the signal output from said operator means to generate a phase compensated signal;
• and
• motor drive means for driving the motor in response to the phase compensated signal.