Principles of thermal printers is that of light material (usually paper) covered with a layer of transparent film, heat the film for some time into dark (usually black or blue). Image is made by heating up, produced by a chemical reaction in the film. This chemical reaction is carried out at a certain temperature. High temperature can accelerate chemical reactions. When the temperature is less than 60 ℃, the film takes a long, even as long as several years to become dark; and when the temperature 200 ℃, it represents will be completed within a few microseconds.
Thermal printer is selected in position heating of heat-sensitive paper, which produced the corresponding graphics. Heating is by contact with heat-sensitive materials provided by a small electric heater on the print head. Heater exhaust square point or by the printer in the form of logical control, when they are driven, on the thermal paper generate a corresponding graphic with the heating element. The same logic circuits that control the heating element and control of feed, and thus be able to print graphics on labels or paper.