| 摘要 |
PURPOSE:To enable to reduce friction loss and noise, by a method wherein a hammer is turned to a retracted position for each printing cycle, and an initial velocity is imparted to an armature at the time of releasing the lock of the hammer, in an impact printer. CONSTITUTION:The hammer 16 selected by a resetting cam 28 and an electromagnetic means 78 is driven toward a type drum to print, and is reset to a stand-by position for printing by rotating the cam 28 for each printing cycle. For each printing period, the hammer 16 is retracted from the cam 28 by a retracting cam 32, and is securely engaged to the armature 82. When the means 78 is not excited, a gap P is provided between the armature 82 and a releasing arm 70b of a hammer locking lever 70, and when the means 78 is excited, the armature 82 is provided with a prestroke, namely, an initial velocity sufficient for releasing the lever 70, so that the lock can be securely released, notwithstanding the fact that the armature stroke is elongated for obtaining the standby and retracted positions. Accordingly, friction loss and noise can be reduced.
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