Thermal Printing - The Cliff Notes
- Thermal printing is an orchestra of many moving parts. The main conductor is the printhead. The printhead is the conductor of heat and composed of little square metal pins or pixels.
- Each metal plate consists of pins and are categorized in dots per inch (DPI). 203 dpi, 300 dpi, & 600 dpi are common options. 203 dpi is used in your typical shipping label whereas the 600 dpi might be used for a small barcode in which the lines need to be clean and crisp in such a small label space, such as tiny circuit board label or a label on your cell phone.
- Each pin can be heated up individually so depending on the image or barcode to be printed, the computer program tells each pin when to heat up and cool down to create the image needed.
- The pins heat and cool as the media (label or tag) move through the printer under the printhead.
- The pins in thermal transfer are square so as each pin heats it leaves a tiny square marking the size of a pinhead with straight edges that allow each marking to line up straight and touch, creating a clean line.
- Other printing technologies, such as laser, use rounded pins and lay down tiny dots.
- This is another reason why thermal printing is the best for printing barcodes. Clean and crisp lines are needed for optimum scanning/reading of the barcodes. Laser printed barcodes might look good to the eye, but under magnification, you can see the blurry edges from the laser printer laying down dots, whereas the thermal square pins allow the edges of the image to touch in a straight line.
2 types of Thermal printing:
Thermal Transfer – (“heat transfer”) in which the thermal (heated) printhead transfers the image onto the media substrate (i.e. label or tag) using a ribbon.