| 摘要 |
PURPOSE:To obtain an impact head free from a response defect under a low service ambient temperature by operating a heating means until the impact head reaches a prescribed temperature when the impact head goes down to the prescribed temperature or below. CONSTITUTION:After printing, a printing wire 2 returns by the spring force of a return spring 10, bumps into a damper 20 and rebounds. Since the damper 20 is hardened at a low temperature, an armature 6 greatly rebounds to make its movement unstable, which may result in a printing defect. However, a thermistor 16 detects the temperature of the impact head to operate a heater 17, whereby the temperature never drops to the degree that the damper 20 is hardened. Under a low service ambient temperature, the rebound of the armature is less to stabilize its movement, thereby preventing a printing defect. A temperature at which the heater 17 starts operating is set at around 7 deg.C, and a temperature at which the heater 17 is switched off is set at 10 deg.C to 12 deg.C. |
