| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a thermal printer which can attain stabilization of a voltage applied to a heating resistance element in the normal printing action, and can attain saving of a checking time in a disconnection check of each heating resistance element. <P>SOLUTION: A switch SW1 is opened, a switch SW2 is closed, and a power supply is supplied from a power supply 22 for checking via a photocoupler PHC and a power supply wire Wp to a common joint of the heating resistance elements THa-THn. The voltage is restricted to not larger than a constant voltage by a Zener diode ZD. A printing control part 71 selectively makes the other end of the common joint of the heating resistance elements THa-THn a ground potential to a head control part 72 via a signal wire Ws. If any of the heating resistance elements THa-THn is disconnected, a current is hindered from flowing to the primary side of the photocoupler PHC, and the secondary side is turned off. The voltage is pulled up by a resistance R1 to 5 V (Vcc), whereby the printing control part 71 detects the disconnection. <P>COPYRIGHT: (C)2006,JPO&NCIPI</p> |
