| 摘要 |
PURPOSE:To eliminate a residual magnetism earlier and to enable to print at a high speed by a method wherein a current of the opposite direction is supplied to a coil after the supply of a current of the normal direction to the coil is finished. CONSTITUTION:When a printing signal S1 of High level is generated, transistors 41, 42 are turned ON and the current iL is supplied to the coil 20 so that an electromagnet 21 is excited. After the input time of the printing signal S1 is elapsed, the signal S1 falls to Low level while a signal S2 rises to High level, and the transistors 41, 42 are turned OFF while transistors 44, 45 are turned ON so that the current iL continues to flow from the terminal A to the terminal B of the coil 20. When the voltage at the terminal B becomes higher, the current iL is returned to the terminal A through a diode 46. When the voltage at the terminal B falls below the Zener voltage, the current iL stops flowing. When the voltage at the terminal B further falls to below that of the magnet power voltage V243, a current flows from the magnet power voltage V243 to the transistor 45 through the coil 20, that is, the current iL of the opposite direction flows in the coil 20 to eliminate the residual magnetism of the electromagnet 21. Accordingly, a needle 29 is returned eary after the printing stroke and hence the printing can be conducted at a higher speed. |
