| 摘要 |
For a print head in an impact dot printer, a drive transistor 33 is connected in series to a head coil 59 that drives a print wire, and a pulse 32 is used to turn the drive transistor 33 on and off. Thus, the drive current i is supplied to the head coil 59 to drive the print wire. The input end of a DC/DC converter 2 is connected to the juncture of the head coil 59 and the drive transistor 33, and the output end of the DC/DC converter 2 is connected to the juncture of a power source 34 and the head coil 59. The DC/DC converter 2 clamps, at a constant level, e.g., 90V, the inductive electromotive force of a high voltage that is generated by the head coil 59 when the drive transistor 33 is rendered off. Then, the DC/DC converter 2 transforms the clamped voltage to a voltage equivalent to the voltage level of the power source 34, e.g., 35V. As a result, instead of energy being wasted by the transistor 33, the energy accumulated by the head coil 59 is returned to the power source 34 and can again be employed, while the input voltage of the DC/DC converter 2 is maintained at a constant level by an initial charger 4. <IMAGE> |
