| 摘要 |
PURPOSE:To make printing density uniform by supplying inverted printing data and printing data to a drive means, then allowing the drive means to drive a thermal printing means based on the inverted printing data and printing data and in turn, the thermal printing means to be preheated, if no printing is yet performed by said means. CONSTITUTION:In a latch circuit 5, a printing data signal is latched by a latch signal and then is connected to an inverting and non-inverting circuit 12. An inversion signal is connected to the other input terminals of Exclusive OR gates 121-12N which constitute the inverting and non-inverting circuit 12, and subsequently, the printing data signal is inverted by the inversion signal. Then inverted printing data is supplied to a drive circuit 7 together with the printing data signal. The inverted printing data signal and the printing data signal are subjected to the control of their pulse width by a strobe signal and as a result, a firing signal is produced. The firing signal is applied to a heat-generating element 8 to allow a constant voltage V to preheat the thermal resistor which does not print during the processing of inverted printing data for producing the fire signal. Next, the constant voltage V allows the heat-generating resistor which prints to generate heat during the processing of non-inverted printing data for producing the fire signal. |
