| 摘要 |
PURPOSE:To obtain a gradation printer with uniform density by sending a heat sensitive paper at fixed speed and almost equally providing heating periods corresponding to density gradations around T/2 after the heating period T of a maximum gradation starts. CONSTITUTION:Assuming that one printing time controlled by a signal ENB is T and printing is executed in N-density gradation, the printing time T is divided into t=T/(N-1). A drive data D2 showing the second density gradation uses the center period t4 during printing time T as a high level, and a drive data D3 showing the third density gradation uses periods t3 and t4 as a high level, a driving data D4 showing the fourth density gradation uses periods t3-t5 as a high level. Similarly high levels are arrayed almost equally before and after the center period t4 up to drive data D7 showing the seventh gradation with the period t4 as a center and drive data D2-D7 are formed. Coloring parts S2-S8 in the heat sensitive paper of printing dots by drive data D2-D8 change their areas in accordance with density gradation and their center is positioned almost in the center of a printing space.
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