| 摘要 |
PURPOSE:To make it possible to carry out the stable injection of a liquid, by making the driving time of a drive signal to impart predetermined amount of preheating to an electrothermal converter for forming flying liquid droplets changeable in accordance with the output from the detecting means of an external temp. CONSTITUTION:When an ink is cooled to a temp. requiring heating or less, the resistance of a thermistor 302 is increased and the output of a comparator 308 comes to H. On the other hand, the amplitude of the output pulse of a circuit 306 is changed corresponding to the change in the resistance value of a thermister 301 due to the change in an external temp. and the pulse amplitude becomes long as a temp. is lowered. These both outputs are inputted in an AND gate 309 and a pulse becomes longer at a lower temp. to bring a transistor 310 to an ON state while low voltage VL not forming scattered liquid droplets is added to a heater 313 to preheat the same. When a printing pulse is applied to a transistor 311, high voltage VH is applied to carry out the injection of the liquid. By this mechanism, stable flying liquid droplets can be formed. |
