Monday, July 23, 2007

Printer types

Impact (Dot-matrix) printers use a set of closely spaced pins and a ribbon to print letters or other characters on a page. These printers actually impact the page to print a character, much like a typewriter. Dot-matrix printers vary in terms of speed and the number of pins they have. They can run at a speed anywhere between 50 and 500 CPS (Characters Per Second). The number of pins, which can vary between 9 to 24, determines the quality of the print job. Dot matrix printers are commonly used for printing invoices, purchase orders, shipping forms, labels, and other multi-part forms. Dot matrix printers can print through multi-part forms in a single pass, allowing them to produce more pages than even high-speed laser printers.

Ink-jets(bubble-jets) printers spray ionized tiny drops of ink onto a page to create an image. This is achieved by using magnetized plates which direct the ink's path onto the paper in the desired pattern. Almost all ink-jets offer a color option as standard, in varying degrees of resolution. Ink-jet printers are capable of producing high quality print which almost matches the quality of a laser printer. A standard ink-jet printer has a resolution of 300 dots per inch, although newer models have improved on that. As a rule color link-jet printers can also be used as a regular black and white printer.

Laser printers operate by shining a laser beam to produce an image on a drum. The drum is then rolled through a pool, or reservoir, or toner, and the electrically charged portions of the drum pick up ink. Finally, using a combination of heat and pressure, the ink on the drum is transferred onto the page. Laser printers print very fast, and the supply cartridges work a long time. Color laser printers use the same toner-based printing process as black and white ( B/W) laser printers, except that they combine four different toner colors. Color laser printers can also be used as a regular black and white laser printer.

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