| 摘要 |
A light beam (7) of a light-source/photocell arrangement (6) is increasingly shaded when a printing hammer (2) moves in the X direction to its point of impact. The shading decreases again when the printing hammer returns into its initial position. The time variation of the photocell current I is differentiated with respect to time t and the flying time of the printing hammer is determined from the distance of the time of excitation (firing time) for the start of movement of the printing hammer to the time of the zero crossing of the differentiation signal (dI)/dt = f(t). Deviations of flying time from a nominal value are compensated under computer control by displacing the firing time of the printing hammer.
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