| 摘要 |
PURPOSE:To prevent heat generation in the motor coil of a stepping motor, layer short, and breakage of the driving circuit for the motor so as to prevent breakage of the motor by providing a logical circuit to stop the driving circuit when a switching means is broken. CONSTITUTION:A comparator 16 compares the voltage in application to coils 1-4 with the standard voltage and outputs a signal when the voltage in application is larger. And a voltage of +5V is applied to the output terminal of the comparator 16 through a resistor 19 and input to an exclusive NOR gate 20 together with a motor driving signal 12. In addition, AND gates 21, 22, 23 and 24 are respectively connected between the output side of the exclusive NOR gate 20 and the base of each transistor 5, 6, 7 and 8 in a driving circuit, and the other input sides of these AND gates 21, 22, 23 and 24 are supplied with specific control signals A, A', B and B' from a control circuit not shown in the diagram. When a transistor 9 is broken the current to the coils 1-4 is cut off forcedly. |
