摘要 |
<p>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.</p> |