| 摘要 |
PURPOSE:To control the dispersion of the color formation of thermosensitive paper and to improve the quality of a printing picture by constantly holding voltage applied to a plurality of resistors of a thermosensitive recording head. CONSTITUTION:A compensation circuit RS is mounted which compensates a change of saturated voltage VCES(QC) between a collector and an emitter of a transistor QC for controlling common signals and constantly keeps applied voltage V(R1-Rn) to resistors R1-Rn, and the impedance of the compensation circuit RS is controlled by means of a comparator CP. The comparator CP detects the number of picture signal controlling signals put out from a picture signal controlling section C1, and generates signals decreasing the impedance of the compensation circuit RS when the picture signal controlling signals are many and signals increasing the impedance of the compensation circuit RS when they are, on the contrary, few. Thus, the dispersion of the calorific power of the resistors R1-Rn diminishes, and the quality of a printing picture is improved. |
