The principle of the thermal printer is heated after a while, which becomes a dark (usually black or blue) film covered with a layer of pale material (usually paper) transparent film. Image Heating is created by the chemical reaction created in the film. This chemical reaction is not at a certain temperature. High temperatures can speed up the chemical reaction. When the temperature is below 60,, the film should go with a long as many years as even being dark; and when its temperature is 200 ℃, this reflection will be completed within a few microseconds. By selecting a thermal printer, it is heated to a predetermined position on the corresponding graphical thermal paper. The contact with the heat sensitive material is provided by a small electric heater with the print head. The heater forms a heating element arranged in square dots or strips guided by the printer logic control with the corresponding graphic on the thermal paper. Heating elements are controlled by logic circuit but also controlling feed can get graphic label or printing on all paper.