| 摘要 |
PURPOSE:To prevent the deviation of printing dot position, unevenness of printing concentration, and blankness of printing by normally operating a printing hammer by a method in which voltage to be applied to a coil is controlled in such a way as to interrupt the increase in suction force resulting from excessive magnetic flux. CONSTITUTION:The number of magnetically driven parts 6 is detected as the reference voltage E proportional to it and then converted into reference voltage F by a function circuit 14, and drive voltage G to be applied to a coil 11 is varied in proportion to the reference voltage F. The function circuit 14 is so designed that the reference voltage F becomes an increasing function of the reference voltage E. Thus, as the number of the magnetically driven parts 6 increases, the drive voltage G is increased and the demagnetization amount Q is reduced. The increasing function is so set that the demagnetization amount Q is always kept at a proper value, and therefore, even when the number of the magnetically driven parts 6 is varied by printing patterns, suction force to be applied to the printing hammer 4 is not changed and printing failure does not occur because the demagnetization amount Q is always kept at a proper value. |
