Rotation control apparatus for use with recording medium

Abstract

Abstract A rotation control apparatus provides servo control over a recording medium, which allows information signals to be read thereto or written therefrom. The apparatus is capable of effecting proper recording or reproduction even immediately after switching of modes. A motor imparts rotary motion to a recording medium; a pulse generator is arranged to detect the rotation of the recording medium and then to output a pulse of frequency proportional to the rotational speed of the recording medium; a servo circuit receives a reference pulse and the pulse output from the pulse generator and then controls the motor to rotate so that the phase difference between the reference pulse and the pulse output from the pulse generator is constant. An internal vertical synchronizing signal generating circuit having a reset terminal, is arranged to supply an internal vertical synchronizing signal of predetermined frequency to the servo circuit as the reference pulse if no reset signal is supplied to the reset terminal, or, if a reset signal is supplied to the reset terminal, to cause the phase of the internal vertical synchronizing signal to coincide with the phase of the reset signal. An external vertical synchronizing signal separating circuit is arranged to receive a composite video signal and to separate an external vertical synchronizing signal from the composite video signal, thereby outputting the external vertical synchronizing signal. A reset-signal supplier supplies the separated external vertical synchronizing signal to the reset terminal of the internal-vertical-synchronizing-signal generating circuit.

Inventors

• 👤 Kouichi Sato

Bibliographic Details