| 摘要 |
PURPOSE: To avoid degradation in an S/N ratio at a normal operation even after a motor current increases during an excitation detection operation.CONSTITUTION: The stepping motor driver circuit (20), including current detection circuits (23) (24) of motor currents and controlling so that an electric current corresponding to a command value runs through by feeding back a detection current, is configured to switch a gain of the current detection circuit and to switch so that the gain is decreased according to an increase in a motor current during an excitation detection operation. By switching connections of resistors R,R,R,Rof the current detection circuits, the gain is switched.SELECTED DRAWING: Figure 3 |
