Thursday, June 12, 2008

Output Devices

Output Devices

An output device displays information on a screen, creates printed copies or generates sound. A monitor, printer, and speakers are examples of output devices.

Some Common Output Devices:

Monitors and Displays

  • Shows the processed information on a screen
    • A monitor uses a Picture Tube like a television with the image displayed on the front of the tube, which is called the screen.

    • Displays are flat and use plasma, LCD, active-matrix, or some other technology.

  • Monitors used to be called Cathode Ray Tubes (CRTs) because of the picture tube, which is a large vacuum tube.
  • A monitor or display produce a soft copy. When the device is turned off the information goes away.
  • Monitors are slowly being replaced by flat panel displays.


  • Printers produce a hard copy
  • The information is printed on paper and can be used when the device is off.
  • It is also called a printout
  • Dot-matrix printers (impact printer)

    • Uses metal pins to strike an inked ribbon to make dots on a piece of paper.
    • Can see the dots that make up the letters or images.
    • Lowest print quality of all of the printers.
    • Very low in cost per page to use.
    • Rarely used today because of the poor print quality, but still used in business to print multi-part forms.

  • Ink jet printers (non-impact printer)

    • Use drops of magnetic ink to produce dots on a page to produce text or images.
    • The print quality is almost the same as a laser printer's.
    • Problems with the ink
      • The ink is very expensive
      • The ink is water soluble and will run if the paper gets wet
    • Highest cost per page of all the printers
    • For producing color documents, it has the highest quality at a reasonable price.

  • Laser printers (non-impact printer)

    • How the laser printer produces an image
      • A laser or LEDs make dots on a light sensitive drum
      • Toner (very tiny particles of plastic) stick to the drum where the dots where made
      • Paper is pressed against the drum and the toner is placed on the paper
      • The paper is heated and the toner melts into the paper
    • Produces the highest quality printout
    • For black and white printouts, very low cost per page
    • Printout is permanent
    • Color laser printers are still fairly expensive ($3,000 to $10,000)


  • used to output sound

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