| 摘要 |
<p>PURPOSE:To prevent the breakdown of a thermal head, by providing a paper feed detection means detecting the presence of paper feed and a conduction control means receiving a signal from the detection means and stopping electric conduction to the thermal head in a paper feed stop condition. CONSTITUTION:A period from a point wherein a preceding sprocket hole 7 is detected by a sprocket hole detection circuit 9 to a point wherein a present sprocket hole 7 is detected is calculated. If the period is within a predetermined value, a paper feed is judged to be normal; on the contrary, if the sprocket hole 7 is not detected after the predetermined period is elapsed, the paper feed is not conducted and judged to be in a stop condition or abnormal. If the aforesaid paper feed stop condition is generated in a printing processing, conduction to a thermal head 2 is stopped by a conduction control circuit 13. Namely, a printing action is forcibly stopped. Therefore, even if a recording paper 5 is wrinkled and jammed in the vicinity of a heating portion of the thermal head 2 for some reason or other, the thermal head 2 free from conduction is prevented from being excessively heated and the failure such as breakdown caused by heat fatigue is avoided.</p> |
