| 摘要 |
PURPOSE:To constantly drive heat generating elements at an optimum temperature, by appropriately controlling preheating energy according to the temperature of a thermal head or the ambient temperature. CONSTITUTION:A heat-sensitive resistor element (thermistor) 3 for detecting the temperature of a thermal head or the ambient temperature is provided, and an energization duration controlling circuit 20 including the element 3 and functioning to vary an energization time for heat generating elements of a thermal head 46 is provided. According to a reference energization time for the heat generating element determined by the controlling circuit 20, a preheating pulse the duration of which is equal to the reference energization time resulting from multiplication by a substantially fixed coefficient is supplied to the heat generating element before printing and/or during printing. By this, it is possible to control the preheating pulse according to temperature variations, to vary the preheating pulse according to a change in a heating value in conformity with the kind of an ink ribbon, and to constantly perform optimum preheating. |
