DOT MATRIX PRINTERS

6/2/2000

Dot Matrix Printers: Dot Matrix printers construct characters or pictures from tiny (or not so tiny) dots. A number of technologies were used. The principle surviving technologies are impact and thermal. Thermal printers use tiny heaters to change the color of heat sensitive paper. Impact printers fire tiny wires ("pins") magnetically at an inked ribbon that is forced into contact with the printing surface.

Most dot matrix printers print a character at a time moving a vertical row of pins across the paper. Although usable characters can be constructed using seven dot high pattern, 9 dot high characters are much more attractive. Modern dot matrix printers are used primarily in commercial/industrial applications and are still the technology of choice for use with continuous form paper. Print heads usually have either 9 or 24 heads. Although many dot matrix printers can operate in graphics mode, they tend to be slow and often have poor to nonexistent gray scale control. Print quality varies from marginal to acceptable. Speed from low to moderate. Cost per page is low.

Principle problems with dot matrix technology include paper handling and other mechanical problems; worn out ribbons; failure of individual pins; ribbons drying out; and overheating of the print head.