| 摘要 |
<p>PURPOSE:To prevent a thermal head from breakage, by detecting an abnormality from a recording signal impressed onto the thermal head and disconnecting a head driving circuit. CONSTITUTION:By conducting comparative monitoring of a line driving circuit 2' output signal and a comparative signal generating circuit 7's basic signal by a comparative circuit 8 at all times, if there was any difference (or discrepancy) between these signals, it is regarded as occurrence of an abnormality and a control circuit 8 is operated. By the operation of the control circuit 8, a line selecting circuit 5, a comparative signal generating circuit 7 and a graphic signal selectig circuit 4 are all turned into a condiction of CUT OFF. And therefore, a thermal head 1 is prevent from being impressed with an abnormal signal and thereby it is prevented from breakage.</p> |
