| 摘要 |
A start-control method is disclosed for an optical disc play-back system comprising an optical disc (1) with an information track to be read, a disc drive motor (27) which rotates the optical disc (1), an objective lens (2) facing the information track, a photoelectric sensor (A to F) which receives a beam of reflected light from the surface of the optical disc (1) through the objective lens (2), a focus servomotor (25) which drives the objective lens (2) in a direction normal to the surface of the optical disc (1), a tracking servomotor (26) which moves the objective lens (2) radially across the optical disc (1), a drive circuit (16, 20) for starting the disc drive motor (27), a focus search circuit (13, 17), a focus servo circuit (12, 17), a tracking servo circuit (14, 18, 19), a disc-drive motor servo circuit (15, 20) for regulating the speed of the disc drive motor (27) at normal operating level, and means (10) for generating control signals for the focus servo circuit (12, 17), the tracking servo circuit (14, 18, 19) and the disc-drive-motor servo circuit (15, 20), the method comprising the steps of energizing the disc drive motor (27) for a predetermined period of time, and then establishing at least the focus search circuit (13, 17) while the disc drive motor (27) continues to rotate due to the force of inertia. |
