| 摘要 |
PURPOSE:To reproduce density with good accuracy, by mounting a correction means for performing correction according to the voltage detected by an applying voltage detection means so that energy to be supplied becomes almost constant with respect to variable density information. CONSTITUTION:A pulse width operation circuit 15 has the functions of not only determining the voltage pulse width to each heat generator of a thermal head 11 on the basis of the count value of a counter 17 showing gradation according to the relation between recording density and an applying voltage pulse width but also correcting the voltage pulse width in order to supplement insufficient voltage to normal applying voltage Vi on the basis of an applying voltage value through an A/D converter 14. When the counter 17 is initially set to a count value 1, the gradation data corresponding to a picture element is compared with said count value 1 by a comparator 18 and, as a result, voltage is applied to each heat generating resistor of the thermal head 11 corresponding to a picture element with gradation of 1 or more from a power source 13. |
