Printer Types
Dot Matrix • An impact printer that transfers characters by striking a pattern (from a matrix) through an inked ribbon and onto paper. • The most common number of pins on a dot matrix printer is 9, 18, or 24. • The speed of dot matrix printers is measured in characters per second (CPS). Common speeds for a dot matrix printer are 32 to 72 CPS. • Dot matrix printers can use either a friction feed or a tractor feed system to move paper through the printing assembly. • Because dot matrix printers strike the image onto paper, it is a good printer to use when carbon-copy documents are being printed.
Formation of images in a dot-matrix printer as shown below.
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Ink Jet (Ink Dispersion) • The ink reservoir is in a disposable cartridge that includes the printing mechanism. • Bubble jet printers print by heating the ink and squirting it through tiny nozzles in the print head and onto the paper. • The crispness of an ink jet printer’s image is usually rated in terms of Dots per Inch or DPI. Ink jets range from 150 to over 1400 dpi. • Ink jet printers feed single cut sheets of paper, from a feed tray, by clamping them between rollers and advancing them one print line at a time, from top to bottom, and then placing the newly printed paper into a tray, other than the feed tray.
Laser • Laser printers are classified as page printers because they print text and graphics simultaneously one complete page at a time.
1. Cleaning: Cleans the photosensitive drum.
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2. Charging: Puts a uniform negative charge on the drum and then wipes the previous image.
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3. Writing: Writing is done with a laser beam striking the drum, then forming the image.
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4. Developing: Image is developed by attracting positive toner onto drum.
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5. Transferring: Transfer corona wire charges paper. Toner from drum transfers to paper.
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6. Fusing: Fuser roller heats the toner and then