Thermal Label Printers: Thermal Transfer & Direct Printing
Thermal Label Printers Explained
The most popular way of printing barcodes is using thermal label printers. They are efficient, fast and reliable, and there are a wide range of printers using this technology on the market. Small footprint desktop printers, mobile printers and high-output industrial printers are all available using thermal printing technology. When there are printers that come complete with label peelers, cutters and re-rollers; it isn't difficult to find a thermal label printer suited suited to your needs.
In thermal label printers text, images or barcodes are created using a print head which heats tiny elements against the label media. There are two variations on the technology which should be explained:
Thermal Transfer Label Printing
This is a very similar method to direct thermal printing (see below) except that a ribbon containing pigment is placed between the print head and the label. Heat causes wax or resin on the ribbon to melt and deposit pigment on the label in the desired image. This eliminates wear to the print heads but adds cost in terms of the replacement of consumables. However labels produced this way are much more durable. Many different kinds of materials can be used in these machines making them suitable for producing a wide range of labels.
Barcodes can be printed with almost all kinds of printing technologies, but it is no accident that thermal label printers are the most well suited to the job. They were pioneered with that specific function in mind. Most printers make very small marks using round dots (inkjet for example). Thermal label printers use square or rectangular shapes to build up an image and this means that the lines within a printed barcode are very sharply defined and can be read reliably. Error free reading is paramount in barcoding, and so what may seem a minor detail is in fact crucial. Also these printers tend to print onto rolls of labels and can print on demand - either a single label or a thousand reducing wastage of label stock.
Direct Thermal Printing
In this method the print head heats the label material itself. The material (usually paper) has been chemically treated and responds to heat by darkening. One of the main advantages of printers which use this method is that they require no extra consumables (ink cartridges, ribbons and so on). However some label materials can be slightly abrasive and eventually lead to degradation of the print head itself which may need replacement after heavy use. The other disadvantage is that these kind of labels are not recommended for long-term use - the coloring has a tendency to fade after some months exposed to light. But generally these thermal label printers are considered to be a very economical choice for many applications.