| 摘要 |
PROBLEM TO BE SOLVED: To eliminate uneven print while preventing the size and cost of power supply from increasing by providing an image gradation generating means, a selection means responsive to the variation of that value, and means for comparing data from both means thereby preventing inflow of a high current. SOLUTION: Data selected by a selector 15 is delivered to a comparator 16 and compared with gradation data from a gradation counter 14. If the gradation data from the gradation counter 14 has a minimum value 0 at the time of initial print, image data is read out one by one from a line memory 13 and then zero data is selected and compared with the value 0 of the gradation data. The operation is repeated for every up count while selecting the image data read out from the line memory 13 or the zero data by means of the selector 15. Consequently, a current is fed only to such gradation data as having a value higher than 0. Since each transistor is fed with a signal only for a time corresponding to the gradation at a corresponding dot position, a current is fed only for a time corresponding to that gradation.
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