| 摘要 |
PURPOSE:To make the coil current of a step motor zero by giving a predetermined positive offset voltage to the input of a voltage comparator and by reducing the reference voltage value of the voltage comparator below the DC offset voltage. CONSTITUTION:Regardless of the current value of a coil 16 a DC offset voltage is optionally given to the inversion input terminal of a voltage comparator 2 by the partial pressure ratio between a resistance 20 and a resistance 21. It is possible to make the current of the coil 16 completely zero, so long as the reference voltage value, which is inputted to the non-inversion input terminal of the voltage comparator 2 where a DC offset voltage is given, is reduced more than that of the equation as shown above the figure. (in which R20 and R21 denote the resistance values of the resistances 20 and 21 respectively. while Vcc denotes the voltage of source.) |
