| 摘要 |
PURPOSE:To prevent the overheat damage of a heat generating section by controlling the supply and stoppage of power applied to a thermal head by signals from a pressure sensor mounted to a substrate of the thermal head. CONSTITUTION:Thermosensitive paper is pushed against a substrate 20 of a thermal head by means of a platen roller 8, an empty surface 24 of the substrate 20 is warped downward only by delta, and a pressure detecting element 27, attached to a notch section 26 of a metallic base 25 glued to the substrate 20, is compressed to change the resistance value thereof. The change is detected by means of an indicator 29, and signals from a pressure detecting circuit C are inputted to the first AND circuit 30 while the signals of the presence of the thermosensitive paper in a microswitch 10 are inputted to the circuit 30. At the same time, picture signals are inputted to the second AND circuit 31, and power is applied to a heat generating section of the thermal head. The signals of the presence of the thermosensitive paper is inputted to the third AND circuit 33 while stepper pulses are inputted to the circuit 33, and the platen roller 8 is turned by means of a driving device 34 and a pulse motor 35. |
