Thermal Transfer Printer / Printing – a printer for printing on paper as well as a selection of other materials; The process of melting a coating of ribbon so that it stays glued to the material on which the print is applied contrasts with Direct thermal printing where no ribbon is present in the process.
Usage of Thermal Transfer printers in industry includes – barcode labels or marking clothing labels, printing plastic labels for chemical containers.
Barcode printers typically come in fixed sizes from 20mm to 250mm wide, the main application for this type of printer is for the production of barcode labels for product and shipping identification.
The printers use a fixed width thermal print head pressing onto a paper or plastic label over a driven rubber roller. Between the print head and label is sandwiched a very thin thermal transfer ribbon (sometimes called foil) which is a polyester film, coated on the label side with a wax, wax resin or pure resin 'ink'.
As the label and ribbon are driven beneath the print head, tiny pixels across the width of the print head are heated and cooled so as to melt the 'ink' off the polyester film and onto the label, this process accounts for the fast speed of the printers and dries instantly.
Thermal print heads are often 203 dots per inch (8 dots per mm) or 300dpi (12 dots per mm), some manufacturers however now make 600dpi printers to produce very small barcodes for the electronics industry such as the battery compartment of a mobile phone.
Thanks to high print speeds, label printers have become very sophisticated with powerful processors and large memory capacities allowing them to produce label images printed at the same speed as the print mechanism. To achieve these speeds almost all thermal label printers use special description languages to allow the label to be laid out inside the printers memory prior to printing.