| 摘要 |
PURPOSE: To control a stepping motor by monitoring the variation of voltage chopped by a clock signal and passed through a filter based on the current value of at least one wire connected between a control circuit and a winding. CONSTITUTION: A power supply circuit CP is provided with resistors R10, R20 and currents flowing through windings E1, E2 are grounded. Consequently, the terminal voltages of the resistors R10, R20 represent the current values of the windings E1, E2. That information is transmitted to a control circuit CC in order to control the power supply circuit CP through wires C11, C12 and C21, C22. The power supply circuit CP feeds a control current to the winding E1 through wires P11, P12 and to the winding E2 through wires P21, P22. A NOT-AND circuit 1 produces a logical sum equal to the potential difference of signals appearing on the wires C21, C22. Upon failure of a stepping motor MP, voltage from a low-pass filter 3 drops below a threshold level for defining a lower limit. |
