| 摘要 |
PURPOSE:To improve the quality of printing by driving interval regulating means according to physical amount relating to the displacement of a piezoelectric element to control the interval between a sheet and an impact wire to a predetermined interval. CONSTITUTION:A displacement DELTAL of the end face of an impact wire 28 with respect to a position at a reference temperature is obtained, for example, from the temperature of a piezoelectric element 13. That is, as the temperature rises, the remaining distortion of the element 13 decreases, and an actual impact interval is broadened by the displacement DELTAL from the present value D. Accordingly, the present impact interval Dr becomes (D+DELTAL). In order to set the impact interval to a set value Ds, the impact interval must be corrected by Ds-Dr=Ds-D-DELTAL. Thus, a motor 52 is rotated at an angle corresponding to Ds-Dr. Then, the present value D stored in a present value counter 7 is updated by Ds-Dr. As a result, the actual impact interval is accurately set to the set value Ds. Therefore, even if the remaining distortion of the element 13 is varied by the temperature change, a printing pressure is so controlled as to always show a set reference value. |
