| 摘要 |
<p>PURPOSE:To prolong the useful life of a thermal head, by inserting a Zener diode between a common electrode and individual electrodes. CONSTITUTION:A Zener diode 12 is inserted between a common electrode 1 and a ground for driving elements 3, whereby surge is eliminated, and it is made possible to perform an accurate resistance measurement during an actual operation and to detect variations in resistance with time. It is thus possible to maintain a favorable printing quality by printing under an optimum condition according to the variations in the resistance. Further, the useful life of heat generating resistors consisting of heat generating resistor element rows 2 is prolonged.</p> |
