| 摘要 |
A position control system for an information storage system, for example, an optical disc system, includes a stepping motor for moving a read-write head and a DC motor for moving a beam reflecting unit, such as an object lens mounted on the head. The position control system drives the stepping motor to compensate a positional error of the beam reflecting unit in a tracking mode after a seek without disturbing the movement of the beam reflecting unit. The position control system includes a master control unit operatively connected to a host controller, a stepping motor control unit, and a track servo control unit. The master control unit activates the stepping motor control unit for a seek operation upon receipt of a seek command from the host controller. The stepping motor control unit drives the stepping motor with a large drive current until the head moved by the stepping motor reaches a position adjacent to a target track on the recording medium. In a tracking operation, the track servo control unit drives the DC motor in response to a positional error of the head at the target track to finely control a position of the head at the target track. The stepping motor control unit drives the stepping motor by a predetermined rotation angle with a small drive circuit to compensate a position of the access end when the position of the beam reflecting unit exceeds a limit of a controllable range of the beam reflecting unit.
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