Impact printing device with an improved print hammer

摘要

An impact printing device having a plunger-type magnet system has an armature consisting of two joined portions which are a cylindrical principal portion and a guide portion which serves as the printing hammer. The principal portion of the armature consists of material of high magnetic permeability and carries a cylindrical peg thereon which mates with a corresponding receptacle in the printing hammer, which is comprised of non-magnetic material. The principal portion and the peg thereon terminate at sharp edges which cause the magnetic lines of force to converge at those edges thereby increasing the kinetic energy available for moving the armature during a printing stroke. A position sensor is connected to a drive circuit for the magnet system for controlling acceleration of the armature on its way to the striking point and deceleration of the armature during a return after a printing stroke in accordance with the speed of the returning armature.