| 摘要 |
<p>A position control system for an information storage system, for example, an optical disc system, includes a stepping motor (7) for moving a read-write head (2) and a DC motor (32) for moving a beam reflecting unit (25), such as an object lens mounted on the head, which drives the stepping motor (7) to compensate a positional error of the beam reflecting unit (25) in a tracking mode after a seek without disturbing the movement of the beam reflecting unit (25). The position control system includes a master control unit operatively connected to a host controller, a stepping motor control unit (8), and a track servo control unit (4). The master control unit activates the stepping motor control unit (8) for a seek operation upon receipt of a seek command from the host controller. The stepping motor control unit (8) drives the stepping motor with a large drive current until the head moved by the stepping motor (7) reaches a position adjacent to a target track on the recording medium. In a tracking operation after the seek operation, the master control unit changes a mode of the stepping motor control unit (8) to the tracking operation and activates the track servo control unit (4). The track servo control unit (4) drives the DC motor (32) 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 (8) drives the stepping motor (7) by a predetermined rotation angle with a small drive current to compensate a position of the access end when the position of the beam reflecting unit (25) exceeds a limit of a controllable range of the beam reflecting unit (15).</p> |
