| 摘要 |
PURPOSE:To enable detection of double feed, by comparing the position of a platen when an adjustment of the gap between paper and a printing head to a predetermined value is finished with the position of the platen at the end of the previous adjustment, and issuing an alarm when the platen positions compared are different from each other. CONSTITUTION:In a paper thickness adjustment, the count on a counter when an output of a sensor 7 is turned ON is l1 for thick paper and l2 for thin paper. After the sensor 7 is turned ON, a platen 1 is lowered further by an amount corresponding to (m+k) pulses, where (m) represents the most lowered position of a printing head 5, and (k) represents an optimum value of the distance between the head 5 and paper 40. When the distance is set to the optimum value, the count on the counter is, x=l+m+k (wherein l is l1 or l2). After the platen 1 is lowered so as to set the gap between the paper and the head to a fixed value, it is checked whether the present operation is the first paper feeding-in operation. When the present operation is the first paper feeding-in operation, the count is saved, whereas when the present operation is not the first paper feeding-in operation, the count on the counter is compared with a saved value. When the count on the counter is different from the saved value, it is judged that double feed is generated, and an alarm is issued.
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