The print head of the thermal discoloration printer is similar to that of the |dot-matrix printer|. Both have a print head block which features a number of metal pins. However, rather that striking a ribbon into paper to achieve an image, the thermal discoloration system heats the pins as they then contact the paper directly. The paper is a special kind which darkens upon exposure to heat. The printhead has a set of heat sinks which allow the pins to cool down rapidly after each character is printed, preparing them for the next character.
