| 摘要 |
PURPOSE:To print with a constantly fixed density irrespective of variations in the environmental condition by individually reading data from various environmental data detectors for detecting variations in the environmental conditions, and calculating an optimum power supply voltage for driving heat generating resistors for printing. CONSTITUTION:In an environmental data detecting part 101, environmental data such as head temperature, ambient temperature for the head and resistances of heat generating elements of the head are converted into analog electric signals such as electric resistances by respective sensors for the data. A data calculating part 103 calculates an optimum printing voltage for printing with a constantly fixed density irrespective of environmental conditions, based on the environmental data inputted. A voltage comparing part 106 compares an output voltage from a level converting part 105 with the printing voltage detected by a voltage detecting part 109 by using a preset ratio, and inputs the result to a voltage controlling part 108. The voltage controlling part 108 regulates the printing voltage V+ so as to equalize the inputs being compared, whereby a printing voltage 111 equal to that set by the data calculating part 103 is outputted. |
