| 摘要 |
PURPOSE:To enable to enhance the frequency of driving a printing hammer, i.e., the printing speed at which characters can be clearly printed, by passing an electric current through a coil for a longer period of time as the number of printing hammers simultaneously driven becomes larger. CONSTITUTION:In a printing head comprising a plurality of magnetically connected printing elements each of which is so constructed that a spring 61 is normally bent through attracting by a permanent magnet 65 and the printing hammer 67 provided at a tip part of the spring 61 is caused to strike by a recoiling force of the spring 61 when the magnetic flux of the magnet 65 is canceled by passing an electric current through the coil 66 to release the bending of the spring 61, the electric currents are passed through the coils 66 for a longer period of time as the number of the printing hammers 67 simultaneously driven becomes larger. For this purpose, the number of the printing hammers 67 to be simultaneously driven is counted by a counting circuit (e), this information is sent to a current-passing period setting circuit (d) to set the current- passed, period, and pulse signals having a pulse width conforming to the current-passing period are fed from a pulse-generating circuit (c) to driving circuits (g) for the coils (h). |
