| 摘要 |
PURPOSE:To prevent the resolution from being degraded by increasing/decreasing the print area in one dot in a device possible for recording half tone. CONSTITUTION:The length (b) in the sub scanning direction of a thermal head is designed shorter than the length (a) in the main scanning direction of each heat element TH. The length l in the sub scanning direction of one scanning corresponds to the unit distance of the heat element, is sectioned by the length (a) in the main scanning direction of one heat element and an imaginary rectangular form corresponds to one dot. When M-th scanning - (M+2)-th scanning are executed, printing (21-23) is executed on a photosensitive paper sheet 2. The length in the width scanning direction of the printed part is proportional to the conductive time of a heat current Ir of the heat element TH1. Thus, the area of the printed part in the dot is changed by changing the conducting time to the heat elements TH1-THn in this way.
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