| 摘要 |
<p>PURPOSE:To automatically set the applied voltage or voltage applying time to a thermal head to a proper value, by a method wherein a heat generating element unused in recording is provided, and the resistance value thereof and the resistance value of a heat generating element used in recording are measured and the lower resistance value is set to reference. CONSTITUTION:A heat generating element R1 is a resistor unused in recording and heat generating elements R2-Rn are resistors used in recording. A current detecting resistor 16 having a known resistance value is connected between the common electrode 15 of the heat generating elements R1-Rn and a power source 14 and the resistance values of R1-Rn are calculated from the voltages at both terminal positions 17, 18 and the resistance value of the resistor 16 by CPU 11. The more recording is performed, the more stress is applied to the heat generating elements used in recording and the rising in a resistance value, that is, the deterioration of the heat generating elements is promoted and, therefore, the average value of R2-Rn is compared with the value of R1 and, when the applied voltage or voltage applying time to the beat generating elements of a thermal head 4 is determined on the basis of the lower resistance value, said voltage or time can be automatically set to a proper value.</p> |
