| 摘要 |
PURPOSE:To perform an accurate current control in a wide load range by increasing the gain of amplifying means if a current level becomes lower than a value corresponding to a load to be set in advance. CONSTITUTION:The output data of a current detector 5 is output to a CPU 1 through an amplifier 70, a sample holding circuit 8, and an A/D converter 9. The CPU 1 controls a current to be supplied to a motor 4 in response to the output data of the converter 9. Here, the CPU 1 turns ON an analog switch 10 when the load of the motor 4 is high to set the gain of the amplifier 70 to a small value, and turns OFF the switch 10 when the load is low to set the gain of the amplifier 70 to a large value. Thus, a current detecting accuracy in a low load range can be enhanced without using the converter having high resolution. |
