| 摘要 |
A print wire driver for dot matrix impact printers comprises a pair of yokes made of magnetic material, a solenoid disposed between the yokes, an armature extending through the solenoid, and a print wire connected to the end of the armature. One of the yokes has first and second projected yoke ends, the other has third and fourth yoke ends, which are opposed to each other. The solenoid is disposed between the projected yoke ends. Between the yokes, a permanent magnet is provided to magnetize both yokes in reverse polarity with each other. The armature and four yoke ends are so arranged as to make two magnetic circuits, one of which is the path connecting the first yoke end, armature and fourth yoke end, and the other is the path connecting the second yoke end, armature and third yoke end. The solenoid is excited alternately in polarity to alternately magnetize the armature. Thus, the armature is reciprocated by the attractive and repulsive forces of the magnetic circuit to drive the print wire.
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