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dot matrix printer

A printer that uses hammers and a ribbon to form images from dots. Used to print multipart forms and address labels, the tractor and sprocket mechanism in these devices handles thicker media better than laser and inkjet printers. Also known as a "serial dot matrix printer."

Hammers Hit the Ribbon
The dot matrix printer uses one or two columns of dot hammers that are moved across the paper. The hammers rapidly press the ribbon into the paper, which causes the ink to be deposited. The more hammers, the higher the resolution. For example, 9-pin heads produce draft quality text, while 24-pin heads produce typewriter quality output. Speeds range from 200 to 400 characters per second (cps), which is approximately 90 to 180 lines per minute (lpm). See line matrix printer.




Dot Matrix Printer
Long after the arrival of laser printers, dot matrix printers have been used to print continuous multipart forms and mailing labels. The tractor feed contains a sprocket that grabs the perforated holes at both sides of the form and pulls it through uniformly.








Dot Matrix Print Head
Dot matrix printers print columns of dots in a serial fashion. The more dot hammers (pins), the better looking the printed results. The print head can get very hot.






Fixed Character Spacing
Unlike laser and inkjet printers, which can create characters of any size, dot matrix printers have limited options.






line matrix printer

An impact printer that prints a line at a time. Printronix pioneered this technology in 1974. Line matrix and band printers are the surviving line printer technologies, but line matrix can print graphics, whereas band printers cannot. Line matrix resolution is in the 70 to 140 dpi range and speeds range from 400 to 1,400 lpm.

Line matrix printers offer medium resolution, monochrome printing with a very low ribbon cost. They also provide high speed; for example, printing a three-part form at 1,200 lpm is equivalent to a 65 ppm page printer. Line matrix printers can exist in harsh conditions and are often found in warehouses and other industrial environments.

A Row of Hammers
The print mechanism is a row of dot hammers that is almost as wide as the page. The hammers are mounted on a shuttle that oscillates back and forth approximately two inches in a track. The hammers are magnetically released at the appropriate time and bang into a ribbon and onto the paper. See printer.




Printronix Line Matrix Printers
Printronix's ProLine line matrix printers range from 475 to 1,200 lpm. Today's line matrix printers are as quiet, if not more so, than laser printers and can function in the harshest industrial environments. (Image courtesy of Printronix, Inc.)





Printronix Printhead
This printhead contains seven sets of print hammers that oscillate back and forth to cover 16" wide paper. The hammers are held back by magnets. The hammer is demagnetized and springs forward onto the ribbon. As it recoils, it is remagnetized back in place. (Original drawing courtesy of Printronix, Inc.)






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