| 摘要 |
PURPOSE:To improve a torque characteristic in high speed drive, and to eliminate step out in a high speed zone by a structure wherein drive method is switched from bipolar drive to unipolar drive in accordance with drive frequency. CONSTITUTION:A control circuit 3 monitors data of drive frequency from a drive frequency monitor 50 at all times. When it is monitored that the drive frequency becomes predetermined drive frequency, the control circuit 3 supplies a signal S(C) for a drive circuit 2 in order to change over drive method for a step motor 1. In accordance with the signal S(C), the drive method for the step motor 1 is switched from bipolar drive in which current is so used as to be caused to flow in both directions to unipolar drive in which current is so used as to be caused to flow in one direction, by the drive circuit 2. |
