| 摘要 |
In a solenoid driven hammer for an impact printer, the armature, which is driven by the magnetic field provided by the solenoid's coil, is integral with the hammer which strikes a printing element on a print wheel. The shape of the pole piece in the solenoid conforms to the shape of the leading surface of the armature to provide a magnetic force field that is of constant strength as the armature is propelled toward the pole piece when the solenoid coil is energized. The hammer, being unitary with the armature, is thereby propelled against the printing element. As the hammer rebounds after striking the printing element, the armature strikes a polyurethane cushion which absorbs substantially all of the energy of the armature/hammer unit, thereby bringing the unit to a complete stop so that the next stroke may be quickly commenced.
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