| 摘要 |
PURPOSE:To print with a uniform density and favorable quality, by sending printing data for the preceding line to a head part by inverting the data, and supplying a preheating pulse signal to a thermal line printer head to heat the head to a predetermined temperature, after completing printing in one line and before printing in the next line. CONSTITUTION:When a printing in one line is completed, the printing data for the line are taken out through an OUT terminal of a shift register 13, and are inverted by an inverter circuit 7. The inverted data are inputted to an inverted printing data selector circuit 6, and are sent to and latched by a latch circuit 12 in response to a control signal from a preheating-controlling means 24 in a microcomputer 2. A preheating pulse signal determining means 22 for determining the width and number of pulses of a preheating pulse signal to be applied to a head 11 reads the temperature t'H of the head 11 detected from a temperature sensor 14. When printing is conducted at a regular time interval Tp, the printing period for the preceding line is subtracted from Tp to calculate a preheating period Th = (Tp-Pp), and the width PH and number NH of pulses of the preheating pulse signal are determined based on a preheating energy lookup table and the preheating period Th. |
