Impact matrix print head solenoid assembly - has permanent magnet to hold print wire armature and deflect spring with electromagnets to overcome magnetic force

摘要

The printing head increases the resulting impact force of the print needle by combining forces from oppositely-directed magnetic fields. A permanent magnet holds an armature connected to a print wire in a retracted, non-printing position, thus applying a holding force to the armature and deflecting a spring coupled to the armature. An electromagnet is energized to produce a magnetic field which acts on the armature and overcomes the field of the permanent magnet. The field produced by a second electromagnet has a component which urges the interconnected armature and print wire away from their retracted position and toward a printing position.