Disc rotation control device for a disc player
AssigneeNippon Gakki Seizo Kabushiki Kaisha
InventorNorio Tomisawa
Life of this patent
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Abstract
A disc rotation control device for a compact disc player comprises a stable rotation detection circuit for detecting whether rotation of a compact disc is in a stable state or in an unstable state, a phase control loop for phase-controlling the disc rotation and direct control means for directly controlling the disc rotation. The disc rotation is controlled by the phase control loop when the disc rotation is in a stable state and, if the disc rotation has become unstable, the control of the disc rotation is switched to one by the direct control means. During the phase control, even if an EFM signal reproduced from a disc has become unavailable for some reason, preceding phase difference data is held and used for the disc rotation control.
Claims10
A disc rotation control device for a disc player in which a disc motor rotates a disc and information is read from the rotating disc to generate a reproduced signal, the control device comprising:
- a stable rotation detection circuit for detecting whether disc rotation is in a stable state or in an unstable state;
- a phase control loop for controlling the disc rotation in accordance with a phase difference between the reproduced signal and an internal reference signal;
- direct control means for controlling the disc rotation wherein said direct control means includes (a) a pattern detection means for detecting a particular pattern in the reproduced signal and determining from said particular pattern whether the disc rotation speed is higher or lower than a predetermined speed, and (b) a circuit responsive to an output of said pattern detection means for selectively producing a pulse signal of a predetermined pulse width to control the disc motor;
- and
- means for switching the control of the disc rotation such that the disc rotation is controlled by said phase control loop when a table state of the disc rotation has been detected by said stable rotation detection circuit and by said direct control means when an unstable state of the disc rotation has been detected by said stable state detection circuit.
Dependencies are inferred from the claim text.