| 摘要 |
PURPOSE: To detect step-out of a stepping motor by providing means for comparing a detection current with a reference current. CONSTITUTION: A reference voltage 119 determined based on the ratio between resistors 117, 118 is fed, along with a shaped waveform 116, to a voltage comparator 120 where they are compared constantly with each other. Then the voltage of the shaped waveform 116 exceeds the reference voltage 119, the voltage comparator 120 delivers a comparison output 121. When a stepping motor steps out, the voltage 112 is subjected to chopping immediately after switching the conducting direction of a coil 101 and the shaped waveform 116 exceeds the reference voltage 119. Consequently, the comparison output 121 of the voltage comparator 120 delivers a signal at the stage of step-out. A control circuit 107 then makes a decision that the stepping motor has stepped out and stops the motor or delivers an alarm to other device. |
