| 摘要 |
<p>PURPOSE:To obtain a low cost thermal head by setting the second potential to a value which is 0.7 time or less the first potential, the third potential to a value as an intermediate potential between! the first and second potentials, and the fourth potential to a value which is less than the second potential. CONSTITUTION:When two common electrodes are provided, the common elec trode 9-1 can select either one of voltages Vo or (2<1/2>-1)Vo by means of a switch 10-1, and the common electrode 9-2 by means of a switch 10-2. The selected either one of the third potential 2<1/2> Vo/2 and the fourth potential 0 V is applied to discrete electrodes 8-1, 8-2,...selected by a drive IC 11. The electric power generated in each thermal resistor 1-1, 1-2,... is such that while the power of a thermal resistor for printing is 1, those of other thermal resistors are 0.17 or 0.085. In this way, the power of the non-selected thermal resistor is 0.5 or less against an effective color developing power. Therefore, a printing error due to a roundabout current can be prevented and therefore, no diode need be provided. Subsequently, a thermal head can be realized at low cost.</p> |
