Thermal Printers

Thermal printers use heat transfer to create text and graphics on the paper. Thermal printers are used in point-of-sale and retail environments as well as for some types of portable printing.

Types of Thermal Printing

Thermal printers are available using two different technologies:

• Thermal transfer

• Direct thermal

Thermal transfer printers use wax or resin-based ribbons , whereas direct thermal printers use heat-sensitized paper. Some printers can be used in both modes.

The Thermal Printing Process

Although both thermal transfer and direct thermal printing involve heating the elements in a printhead to a particular temperature to transfer the image, there are some differences in operation. The basic process of thermal printing works like this:

1. The printhead has a matrix of dots that can be heated in various combinations to create text and graphics.

2. The printhead transfers text and graphics directly to heat-sensitive thermal paper in direct thermal printing, or to a ribbon that melts onto the paper in thermal transfer printing.

3. If a multicolor thermal transfer printer is in use, each ribbon is moved past the printhead to print the appropriate color .

Figure 10.12 compares direct thermal and thermal transfer printing technologies.

Figure 10.12. Direct thermal (top) and thermal transfer (bottom) printing technologies.

Suitable Paper and Label Stock for Thermal Printers

The best paper and label stock to use for thermal printing depends upon the type of thermal printing to be performed.

If the printer uses direct thermal printing, heat-sensitive paper with characteristics matching the printer's design specifications must be used. For portable printers using direct thermal printing such as the Pentax PocketJet series, the usual source for such paper is the printer vendor or its authorized resellers. If the direct thermal printer is used for bar codes or point-of-sale transactions, you can get suitable paper or label stock from bar code or POS equipment suppliers and resellers .

If the printer uses thermal transfer, most smooth paper and label stocks are satisfactory, including both natural and synthetic materials.