| 摘要 |
PURPOSE:To stabilize the constant current control of a magnet coil in an impact printer by providing reference voltage loading means for controlling ON, OFF to supply a reference voltage with respect to a differential amplifier in a constant current controller. CONSTITUTION:A reference voltage Vs fed from a reference voltage generator 11 is normally loaded to a reference voltage loader 20 having one transistor Tr3 except an exciting time of a magnet coil 13, and the supply to a differential amplifier 15 of a constant current controller 12 is turned OFF. Then, a TR3 in the loader 20 is turned OFF together with a transistor TR2 in a switching unit 14 during the exciting period of the coil 13, a reference voltage Vs is supplied to the amplifier 15, and a constant current from the controller 12 is supplied to the coil 13. Thus, the constant current control is always executed stably by a simple method, and a printing quality is largely improved at an impact printing position. |
