THE TECHNOLOGIES OF LABEL PRINTERS
Label printers use a variety of printing technologies. Some types of label printers are:
The thermal transfer printer, which is a non-impact printer that uses heat to make an impression or image on paper. The printer has a printhead containing many tiny resistive heating pins that on contact, depending on the type of thermal transfer printer melt wax-based ink onto ordinary paper or burn dots onto special coated paper. A microprocessor determines which of the individual heating pins are heated to produce the printed image. The printhead spans the entire width of the label to be printed on. Thermal transfer printers are popular for printing bar codes; price tags, labels, and other specialized print jobs. There are two different types of thermal transfer printers: direct thermal and thermal wax transfer.
The direct thermal printer prints the image by burning dots onto specially coated paper as it passes over the heated printhead. Direct thermal printers do not use ribbons. The early fax machines used direct thermal printing. Direct Thermal labels are made from chemically sensitized paper that turns black when heated. A roller advances the labels and presses them against the printhead, which contains a row of miniature solid-state heating elements. The printer's internal microprocessor turns the elements on and off to form the printed image. Depending on the resolution of the printer, print quality can range from 150 to 600 elements per inch.
Thermal wax transfer printers uses the same printing mechanism as the dye sublimation printer, but rather than laying down a transparent die, it melts dots of wax-based ink that adhere to almost any kind of paper stock, from ordinary paper to complex synthetics and film. Thermal transfer printers produce various shades of colours by placing colour dots side by side. Printing much faster than dye sublimation, the consumables, the ribbon and paper, are also less expensive, but cannot produce photorealistic quality.