| 摘要 |
<p>PURPOSE:To prevent misprinting from occurring and prevent instantaneous breakdown of a heating resistor from occurring, by connecting a surge voltage absorbing Zener diode to a common electrode. CONSTITUTION:A Zener diode 261, 262 is connected between a common line C1, C2 and earth. The Zener voltage is set between a rated output voltage of a power source circuit and a maximum allowable surge voltage, thereby preventing instantaneous breakdown of the thermal head from occurring. When printing data 231, 232... are impressed on NAND gates 221, 222... from a shift register, a strobe signal 24 is generated to print by pulses impressed on the lines C1, C2. Though the Zener diodes 261, 262 absorb the surge voltages contained in the printing pulses, they do not accumulate electric charges. Accordingly, discharge phenomena do not occur during the next printing cycle, so that there is no possibility of misprinting.</p> |
