| 摘要 |
PURPOSE:To increase the starting torque by providing a differential amplifier to which a reference voltage and the output voltage of the DC motor are supplied thereby the overload condition is detected. CONSTITUTION:A reference voltage generating circuit 11, a voltage comparing circuit 12, an output circuit 13, and a constant current circuit 14 constitute the control circuit for the DC motor 10. The output of the reference voltage generating circuit 11 is connected to one input of the voltage comparing circuit 12, and the output of the current mirror circuit to the output circuit 13 is fedback to the other input, thereby the counter-electromotive force Ea of the DC motor 10 becomes constant and the motor is driven at a constant rotational speed. At the normal operation, since the two inputs of the voltage comparing circuit 12 are balanced, differential-type detecting transistors Q4 and Q5 are balanced and the equal collector currents are supplied. Since the values of resistors R1 and R2 are determined as R1>R2, a transistor Q6 is turned OFF and Q7 is turned ON. At the time of starting, since the transistor Q4 is turned OFF, Q5 is turned ON, Q6 is turned ON, and Q7 is turned OFF; and the torque is increased. |
