| 摘要 |
<p>PURPOSE:To avoid needless printing, by a method wherein abnormality in current-passing conditions in a thermal head is detected, and stopping of a printing action is also controlled concurrently with turning-off of a driving circuit. CONSTITUTION:The output of an AND gate 34 is inverted to a low level when being impressed with either one of an overlapping printing command detection signal 35A from a printing command detecting circuit 35, an overcurrent detection signal 37A from an overcurrent-detecting circuit 37 and an excess current- passing period detection signal 36A from a current-passing period detecting circuit 36. Accordingly, a driving circuit 32 is controlled by a switching circuit 31, and is turned OFF. On the other hand, the printing action is also stopped by signals 35A-37A corresponding to abnormalities in current-passing conditions in the thermal head, and an needless printing action such as a movement of a carriage is prevented. Accordingly, the thermal head is prevented from being broken, and a breakage accident can be prevented from being propagated.</p> |
