Impact Vs. Non Impact Printers
By John Papiewski
Impact-type printers dominated the computer scene up to the 1990s, when manufacturers introduced reasonably-priced inkjet and laser models for the desktop. The two main types of printers, impact and non-impact, use different types of mechanisms: impact printers have more mechanical parts, and non-impact types employ more electronic finesse to create printed pages. Though your PC can use either type of printer, the non-impact type is better-suited to quiet office environments.
An impact printer drives formed metal type or metal pins into an inked ribbon at high speed, producing characters on a page. A dot-matrix printer, for example, has a print head containing a tight column of nine stiff wires, each with its own electronic actuator. As the print head scans back and forth across the paper, the actuators fire, driving the wires into a ribbon, which in turn strikes the paper. The pins fire in a horizontal sequence, forming characters, bar codes and other simple graphics. Inkjet printers, a non-impact technology, spray tiny, carefully-controlled ink droplets from a cartridge as it moves across the page. Though the cartridge is sophisticated, the rest of the printer is mechanically simple. Another non-impact technology, laser printing, uses a laser beam to "draw" text onto a metal drum. The laser light produces a static charge wherever it touches the drum; powdered toner clings to it because of the static electricity. A roller presses the paper against the drum, transferring the image to the page; a hot fuser mechanism melts the toner into the paper, making the image permanent.
Resolution and Colors
Laser and inkjet printers turn out high-quality text and graphics at resolutions of 300 dots per inch and higher. In "draft mode," dot-matrix impact printers produce graphics at 72 dpi; higher-quality modes overlap the dots slightly, raising the resolution to over 300 dpi. Non-impact printers come in monochrome and color varieties, combining yellow, cyan, magenta and black to produce thousands of shades and hues. Impact printer color depends on the ribbon, which is usually black or red.
In draft mode, dot-matrix printers print from 200 to over 1,000 characters per second. High-quality mode fills the same characters with extra dots, making smoother image but cutting the print speed to 100 cps or less. Chain printers, another impact technology, print a line of characters at a time, with the fastest models capable of 2,000 lines per minute. Laser printers produce output at rates ranging from four to 24 pages per minute, with industrial models printing up to thousands of pages per minute.
Dot-matrix printers are comparable in cost to desktop laser printers, although the supplies for dot-matrix models are much less expensive. Operating costs for dot-matrix technology runs from .1 to .15 cents per page. Line printers have similar costs. Non-impact printers cost much more, at 1 to 9 cents per page for laser and LED printers, and 3 to 30 cents per page for inkjet technology.
Impact printers suffer from high noise levels due to the clatter and buzz of metal hitting paper. Laser printers produce light noise from the paper feed mechanism and cooling fans. Inkjet printers make a slight shuffling sound as they print, and their paper feeder also makes some mechanical noise.
Chicago native John Papiewski has a physics degree and has been writing since 1991. He has contributed to "Foresight Update," a nanotechnology newsletter from the Foresight Institute. He also contributed to the book, "Nanotechnology: Molecular Speculations on Global Abundance."