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Output Devices

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Output Devices

Output devices are used to produce the output of the machine in a human-readable form. The most common output devices are monitors, printers, plotters, and speakers, etc.

Monitor

Monitor is the most common form of an output device that is used to display output on the screen. The picture on a monitor is made up of thousands of small colored dots called pixels. The three most common types of monitors are CRT (Cathode-Ray-Tube), LCD (Liquid Crystal Display), and LED (Light Emitting Diode/Display), etc.

Printer
Printer is used for creating paper copies. Printer can produce text and images on the same paper. Printer can be divided into two distinct categories:-
  • Impact Printer
  • Non-Impact Printer 
1. Impact printer- In these printers there is mechanical contact between the print head and the paper. Impact printer comes in a lot of varieties such as Line printer, Drum printer, Daisy wheel printer, and Dot Matrix printer

Dot Matrix printer 
It prints one character at a time. The printing head of DMP contains a vertical array of pins. As the head moves across the paper selected pins fire against an inked ribbon to form a pattern of dots on the paper to form a character.

Advantages of DMPs
  • Low operating cost
  • Can print continuous stationery(Create carbon copies)
  • They are robust and can be used in dirty or Harsh conditions
  • Can use carbonated paper
Disadvantages of DMPs
  • Low resolution
  • Print quality is too poor
  • Very slow
  • Very noisy
  • Cannot produce color copies
2. Non-impact printers- In these types of printers there is no mechanical contact between the print head and the paper. Here we have two basic examples of non-impact printers

Inkjet printer
Inkjet printer's fires extremely small droplets of ink to the paper to create an impression of text and image

Advantages of inkjet printer
  • Good resolution, they can print good quality results
  • Cheap to buy
  • Fast compare to Dot Matrix printer
  • Very quiet
  • Can print black and white and color print on the same page
Disadvantages of inkjet printer
  • Cartridges costly
  • Output is ink-based and will smudge if the printout gets wet
  • If used for a long period of time the cartridges can easily dry out
Laser printer

Laser printer produces high-quality text and graphics print by exposing a laser beam back and forth over an electrically charged drum. Then it attracts a toner that forms the image and prints it into the paper.

Advantages of laser printer
  • Very high resolution 600 to 1200 DPI per inch
  • Very fast
  • Almost silent
  • Running cost is lower
Disadvantages of laser printer 
  • Expensive to buy
  • Expensive to repair
  • Can't use continuous stationery that means cannot create carbon copies
Plotter 
Plotters are output devices that produce good quality drawings and graphs. There are two basic types of plotters- drum plotter and flatbed plotter

Advantages of plotter
  • Drawings are of the same quality as if an expert drew them
  • Plotters can produce output on large sheets.
Disadvantages of plotter
  • Plotters are slower than printers
  • More expensive to buy than printers
  • Plotters are not suitable for text
Speaker 
Speaker receives constantly changing electric current from the sound card then this current is transferred to a magnet which pushes the speaker back and forth this way pressure vibrations are generated that create sound. Computer system speakers are usually smaller and they contain their own small amplifier.


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