| 摘要 |
In a thermal printer, resistance values of individual heating elements of a thermal head are measured to check if there is any heating element that breaks down. If a broken heating element RN is determined, heat energy values YEn, YEn- 1 , YEn+ 1 , YEn- 2 and YEn+ 2 necessary for pixels to be printed by the broken heating element RN and neighboring heating elements RN- 1 , RN+ 1 , RN- 2 and RN+ 2 are calculated. The heat energy values YEn- 1 , YEn+ 1 , YEn- 2 and YEn+ 2 are corrected by adding predetermined percentages of the heat energy value YEn of the broken heating element RN to these values. Based on the corrected heat energy values YEn- 1 , YEn+ 1 , YEn- 2 and YEn+ 2 , image data for the neighboring heating elements RN- 1 , RN+ 1 , RN- 2 and RN+ 2 are corrected. The heat energy generated from the neighboring heating elements increase so much as to print also the pixels assigned to the broken heating element, preventing white streaks.
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