| 摘要 |
A halftone printing system according to this invention comprises reference level generation means for generating a reference gradation level, decision means for comparing a gradation level input signal with the output signal from the reference level generation means and deciding if the gradation level input signal is at or above the reference gradation level, count means for counting the number of output dots from the decision means and delivering heat accumulation information on heat accumulated in a thermal head, and a pulse generator which generates the number of pulses, or the width of a pulse, corresponding to the gradation level input signal in accordance with the heat accumulation information from the count means or with the heat accumulation information and temperature information from the thermal head. Also, the halftone printing system according to this invention further comprises white line detection means for detecting a white line included in the input signals, white line count means for counting the number of continuous white lines in correspondence with the detected results of the white line detection means, and white line decision means for applying a predetermined signal to heat accumulation index-count means, depending upon the count value of the white line count means.
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