PC Hardware —

Thermal Printers

A thermal printer heats spots on paper with an array of tiny, fast-acting heating elements. At one time, these printers were an inexpensive alternative to dot-matrix printers for the low-end, low-volume market, even though their paper costs were much higher. Early fax machines, today's non-plain-paper fax machines, and some label makers are examples of thermal printers. For uses other than faxing, this type of printer is rare, too. You might find it used to print simple sales receipts.

Thermal printers print more quietly and usually faster than impact dot matrix printers. They are also smaller, lighter and consume less power, making them ideal for portable and retail applications.

Thermal Wax-Transfer Printers

A thermal wax-transfer printer uses heat to bond a wax-based pigment to paper. These printers usually have resolutions of 150 or 300 dpi. At one time, these devices were used for color graphics and photo-reproduction; more recently, they have been replaced by ink-jet and color laser printers, which are less expensive to own and operate.

These printers use a thermal transfer ribbon that contains wax-based ink. Heat is applied to the ribbon using a thermal printhead that melts the ink transferring it to the paper where it is permanent after it cools. A typical thermal transfer ribbon consists of three layers: the base material, the heat melting ink, and the coating on the print side of the base material. The bewildering assortment of transport rollers, heating arrays, and electronics make field repair of these printers impractical, except by a specially trained technician equipped with special tools.

Direct Thermal Printers

The direct thermal printer prints the image by burning dots onto coated paper as it passes over the heated printhead. Direct thermal printers do not use ribbons. Early fax machines used direct thermal printing.

Daisy-Wheel Printers

Once popular, the daisy-wheel printer is now a rare form of impact printer. A daisy-wheel device prints characters one at a time using a circular printer element that produces letter-quality output. Each printer element contains characters of only one font, which means that every time you want to change fonts (for example, from Courier to Times Roman), you must manually change the element. In this respect, these printers are similar to some electric typewriters; these devices produced clean type, along with lots of noise and often a great deal of vibration. If a client has a daisy-wheel printer that needs repair or replacement, consider recommending a laser printer instead.