| 摘要 |
PURPOSE:To perform high-density gradation printing at a high printing speed and to uniformize the surface of a print by preventing the thermal surface roughening of photographic paper, by comparing gradation data with reference data and controlling the time of heating applied to a thermal head. CONSTITUTION:The gradation data counted by a counter 3 is inputted to a comparator 4 controlling a thermal head heating cycle. The number of gradations to be continuously heated which has been latched by a latch circuit 6 has been preliminarily inputted to the comparator 4 to compare the gradation data with the number of gradations instructed from CPU5 and, if the gradation data is larger, an output of 'H' level is inputted to the clear terminal (CR) of a flip-flop 7. CPU5 outputs the signal controlling the heating cycle of the thermal head and the informations latched by latch circuits 8, 10 are selected by a multiplexer 9 to be inputted to a comparator 11. The signal of the printing time corresponding to one gradation is inputted to the comparator 11 and, when two inputted data coincide, coincidence output goes to the clock input of the flip-flop 7. |
