| 摘要 |
PURPOSE:To attain speed-up and power saving of preheating as well as lengthen the life of thermal head by utilizing the heat of resistors for driving a stepping motor to raise the internal temperature for preheating of a thermal head. CONSTITUTION:When the temperature of open air is low, the output of a temperature detector 7 is compared with reference voltage source 8 by a comparator 9. By the output voltage, a current switching circuit 5 is switched so that the resistor pair 4 of B set on the back of thermal head is connected to the power source 6. A stepping motor 1 is driven and at the same time the thermal head is quickly heated by the heat of the resistor 4. When the head reaches a printable temperature, the output of the comparator 9 is changed to switch the circuit 5, and drive current is supplied to the motor 1 through the resistor pair 3 of A earthed in a place where ventilation of air is good. In this case, the heat produced in the resistor pair 3 is released to outside and the effect of heat on the thermal head can be avoided. |
