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How do Direct Thermal Printheads Work?

Thermal printers are commonly used to meet a variety of printing needs, including barcodes and print receipts. But how do direct thermal print heads really work?

As one would expect, thermal printers are so named because they use heat to create images rather than ink or lasers.  For direct thermal printing, this heat is generated by a thermal printhead, which reacts with thermo-sensitive paper.  The paper is fed through the printer by the platen, which is a simple silicone-based roller, and the heat activates the paper, changing its color. 

Thermal printheads are the essential component of thermal printing.  The printhead is covered in silicone glass and has a very thin wire, called the print line, that receives electrical signals from even thinner wires during the printing process.  Each of these minuscule wires can produce a “dot” of heat on the print line, and most thermal printheads have 203 of these dots per inch. 

The common measurement “dpi” refers to the density of these wires and thus the density of the final print.  The thermal printhead is located on top of and parallel to the platen.

GoDEX DT2x 2 inch Desktop Direct Thermal Printer


Each thermal printer is equipped with a controller board that can be embedded with firmware to manage multiple barcodes and other printing demands such as fonts, logos, and printing size.  The controller board can also recognize when the paper is low or what parts of the machine are open, just as with traditional printers.

So why should you use thermal printers? First, they are quieter and faster than other types of printers, not to mention more compact and energy efficient.  In addition, since many thermal printers use roll-based paper, they are quick and easy to refill, making them ideal for fast-paced work environments. 

Thermal printers are widely used in cash registers, gas station pumps, print-on-demand labels and even for making real-time recordings in-hospital cardiac monitors and for ultrasound scans.  They are definitely worth considering for your business.

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