PRINTER DRIVE

摘要

The electromagnet coil (L) associated with each print needle or hammer is wound on a core to which an armature is held when the coil is de-energised. The current is limited in intensity by a diode (D4) and resistance (R1) in a transistor circuit (V1) for the duration of the initial pulse. This is succeeded by an interval in which an energy recovery capacitor (C) is charged from the coil (L), via another diode (D2), to a voltage limited by a Zener (D1). Finally the capacitor (C) is discharged through another transistor (V2) and an adjustable resistance (R3) into the coil (L).