| 摘要 |
PURPOSE:To prevent a pulse waveform drive circuit and a driven device from damaging by detecting and integrating a pulse waveform drive current, and comparing it with a reference voltage to detect a malfunction. CONSTITUTION:A drive current supplied through a transistor TR to the exciting phase L of a stepping motor is detected by a torque correcting resistor R and an amplifier 6. An integrator 7 integrates the waveform (1). The integrated value (2) is compared by a comparator 8 with a comparison voltage E. This comparison voltage value E is set to a value larger than the integrated value of the pulse waveform and smaller than the integrated value from the same continued voltage value as the maximum value of the pulse waveform. If the comparator 8 detects the integrated value exceeding the comparison voltage value, a power source interruption signal is delivered. |
