| 摘要 |
PURPOSE:To enable the temperature of a thermal head to be raised to a temperature proximate to a color forming temperature immediately before printing in each color, by sending to the thermal head a preheating pulse suitable for the temperature of the head. CONSTITUTION:With a preheating signal inputted from a system controller for a fixed period of time, a black data changeover switch 10 is changed over to the side of a black data-generating circuit 8, and an energization pulse changeover switch 11 is changed over to the side of a preheating pulse-generating circuit. On the other hand, the temperature of a thermal head 14 is detected, and temperature data is transferred to a preheating period-varying means 20 and a preheating pulse duration-varying means 21 together with a color discrimination signal which is switched for each color. The period-varying means 20 selects a preheating pulse period suitable for the head temperature and the color through which printing is performed, generates a preheating period signal. Synchronously with this, preheating pulse duration data suitable for the head temperature and the color through which printing is performed, generated by the duration-varying means 21, and is transferred to a pulse-generating circuit 17. The generating circuit 17 generates a preheating pulse based on the period signal and the pulse duration data, and output the pulse to an energizing switch 13 for a heat generating element. |
