| 摘要 |
PURPOSE: To obtain a pull-in torque at the time of starting higher than the maximum load torque by increasing the drive frequency of a stepping motor at the time of starting gradually from a level corresponding to the pull-out torque at a predetermined drive frequency to a predetermined drive frequency. CONSTITUTION: When a body touching an electrode 4 is detected, the first exciting coil of a stepping motor 1 is conducted for a time interval sufficiently longer than that for steady operation thus setting the rotor at an optimal starting position. Subsequently, the drive frequency is increased gradually from a level lower than the steady drive frequency to the steady drive frequency. Since the pull-in torque can be set higher than the steady drive frequency, a stepping motor 1 having a pull-in torque at the steady drive frequency lower than the maximum load torque can be employed. |
