| 摘要 |
<p>PURPOSE:To make it possible to eliminate the density irregularity of the whole of a printed image, that is, between a writing start part and a writing finish part, by performing printing by applying max. voltage to the first line of a print and subsequently voltage attenuating timewise to a thermal head. CONSTITUTION:A character S1 is a printing start signal and the signal S2 sent from a separate control circuit shows a signal held to a 'H' state only for a time t1 controlling the voltage of the power source of a head. By bring said signal S2 to a 'L' state through an inverter only for the time corresponding to the length t1 of the wave form generated in a timer, a relay Rey is operated and an A-terminal is turned ON. When the signal S2 is held to the 'L' state, a B-terminal is an ON-state and a condenser C is charged in quantity corresponding to the values of resistors R4, R5. When the A-terminal is turned ON, the voltage obtained by dividing voltage Ee by resistors R2, R3 is superposed to voltage Ec and voltage EI finally comes to the output voltage Eo of a power source and said voltage Eo is supplied to the head. This wave form becomes the same to voltage Eo and a print having no density irregularity is obtained by this circuit.</p> |
