No, the working principle of thermal printer is to install a semiconductor heating element on the print head, and the print head can print the required pattern after heating and contacting the thermal printing paper. The principle is similar to that of thermal fax machine. The image is produced by heating to produce a chemical reaction in the film. This chemical reaction is carried out at a certain temperature. High temperature will accelerate this chemical reaction. When the temperature is lower than 60℃, it takes a long time for the paper to turn black, even several years. When the temperature is 200℃, the reaction will be completed in a few microseconds.

The thermal printer selectively heats the thermal paper at some positions, thus producing corresponding graphics. Heating is provided by a small electronic heater on the print head in contact with heat-sensitive materials. The heater is logically controlled by the printer in the form of square dots or strips. When driven, a pattern corresponding to the heating element is generated on the thermal paper. The same logic circuit that controls the heating element also controls paper feeding, so that graphics can be printed on the entire label or paper.

The most common thermal printers use a fixed print head with a heating grid. The print head has 320 square lattice, each lattice is 0.25mm×0.25mm With this lattice, the printer can print at any position of thermal paper. This technology has been applied to paper printers and label printers.