| 摘要 |
An impact printer including a platen, a carriage mounted for reciprocating movement generally parallel to the platen, a rotatable print element having character imprinting portions disposed thereon, the characters being assigned a class designation according to their imprinting area, a print element selector for moving the print element to position a selected character portion at a printing position, a hammer for driving the character portions to deform the platen, and means for driving the hammer toward and away from the platen. Different impact velocities are assigned to the hammer in accordance with the character portion class designations. The rate of hammer displacement is varied as it is moved from a home position to an impact position so that the hammer initially moves through a first region wherein it is rapidly displaced at an increasing velocity and subsequently moves through a second region wherein it is slowly displaced at a substantially constant velocity. A counter is incremented periodically in response to the hammer movement for determining the instantaneous location and velocity of the hammer, and the counter is reset with a predetermined count, notwithstanding the actual count, at a location within the second region.
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