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.