| 摘要 |
PURPOSE:To eliminate variations in printing density and to improve printing quality by a method wherein heating temperature of heating elements is made different between while non-printing and while printing. CONSTITUTION:A printing signal in response to one cycle of reference clock pulses A is input to each input terminal 6 of a gate 2 so as to control on-and-off operation of transistors Tr1-n which are serially connected to heating elements H1-n, respectively. Respective output terminals of the gate 2 come into the floating state when an output terminal of an inverter 4 assumes a high level, i.e., when the pulse A is low, so that the transistors Tr1-n are turned on and a minute current from FET is supplied to the elements H1-n thereby to preheat them. When both the pulse A and the signal B are high, the output terminals of the gate 2 become high. At this time, since the FET is conducted, source voltage VCC is applied to the elements H1-n directly and temperature of heat-sensitive paper is raised up to such a level that it develops color. When the pulse A is high and the signal B is low, the output terminals of the gate 2 become low. In this state, the transistors Tr1-n are not conducted and the elements H1-n are supplied with no power and hence not heated. |
