| 摘要 |
PURPOSE:To stably operate a device in a short time by beginning to move without waiting for the supply of a pulse that specifies the moving distance of a head and feedback-controlling a DC motor from the difference between a step pulse showing a target track position and a current position from an encoder. CONSTITUTION:The moment the supply of the step pulse corresponding to an amount that a magnetic head moves to a control means 4 starts, the head begins to move. Since the frequency of the pulse is accelerated due to the move of the head, the difference between the target position of the head and current position information expands slowly, and a signal supplied to a drive circuit 4 becomes lager. The speed of a motor becomes MAX. After pulse supply ends at a point P5, the difference between the target value and a measured value decreases slowly. However, the motor 1 remains MAX if the difference is beyond a range stored 4a in a command table. When the difference lies within the range, the motor 1 begins to slow down at a point P2, enters a slow running at a point P3 just ahead of a target track, and stops on the target track. With this control mechanism, seek time can be shortened. |
