OUTPUT DEVICES

An output device is a piece of hardware used to display output or data which has been processed on the computer.

 

CRT Monitor

Monitor (screen) is the most commonly used output device hence monitor is called as the standard output device. The picture on a monitor is made up of thousands of coloured dots called pixels. Higher the number of pixels per unit area, higher will be the quality of picture.

 

Plasma screens

Plasma screens are new technology for televisions.

 

Plasma screens are used for:

  • TV screens in home
  • Computer screens
  • Screens in airports for information , advertising or displays
  • Screens in videoconferencing suits for meeting

 

Advantages of plasma screen:

  • Very large screen size
  • Unaffected by magnetism
  • Brighter display than rear projection TVs
  • Very thin, so occupies less space, also can be mounted on walls or ceilings

 

Disadvantages of plasma screen:

  • ‘Burn-in’ Because of phosphor technology used, it is possible for traces of image to be burnt-in to the screen
  • Shorter display life when compared to LCDs
  • Consumes more power and generate more heat

 

Printers

Printers are common output device. They are used to create ‘hard’ copy of documents. Inkjet printers are good for low volume as they produce excellent text and photo outputs, cost per page is expensive.

Laser printers are better cost-effective choice for large volume prints.

Laser printers:

  • are quiet, so could be used in offices
  • produce large number of prints very quickly
  • produce high quality prints
  • have powdered ink called ‘Toner’ is fused onto paper by heat and pressure.

 

Advantages of laser printers:

  • High quality printouts
  • Faster than inkjet printers
  • Cost per page is lower than inkjet printer

 

Disadvantages of laser printer:

  • Most expensive printer to purchase
  • Toner is more expensive
  • Expensive to repair
  • Can’t be used for making carbon copies


Inkjet Printer

Prints characters by sparaying drops of ink onto the paper

Advantages:

  • Printer is cheap
  • Produce good quality printouts
  • Suitable for home and small offices (small scale printing)

 

Disadvantages:

  • Cost per print is high
  • Not suitable for large scale printing
  • Need to change cartridges very often

 

Dot-matrix Printer

Advantages

  • Very cheap
  • Can produce carbon copies of prints

Disadvantages

  • Not suitable for office places as it makes large sound
  • Print quality is very poor

 

Digital projector

A digital projector is a device which is connects to a computer and is used to project the video output from the computer onto a wall or a large screen.

Uses of digital projectors are:

  • Class room teaching
  • Staff training session
  • A presentation to an audience
  • Home cinemas

 

Speakers

Computers come with an internal speaker, which can make beep sounds. In addition to the internal speaker computers can also be fitted with sound cards which will enable sound to be output through external speakers. These speakers produce high quality sound.

 

Lights

Lights such as LED can be connected to computer to display outputs. Eg: traffic lights

Advantages:

  • It is independent of languages
  • Very cost effective way of indicating the status of an equipment
  • They can give warning for users with hearing loss.

Disadvantages of Light:

  • The light may break and need replacing
  • There may be loose connection which means light doesn't turn on
  • They can only indicate simple status (ON/OFF) – anything more complicated would need a separate display screen.

 

Headphones and earphones

They have a pair of small speakers which are worn over or in the ear. They are connected either by a cable or wireless to a computer.

Advantages:

  • Sound can only be heard by user
  • Portable – light weight and easy to carry
  • Can listen to music on the move
  • Not very expensive

 

Disadvantages:

  • If used for long periods of time there is a risk of permanent hearing loss
  • User might be unaware of the noise around, cars in traffic, people talking etc.
  • Uncomfortable to wear for long period of time

 

Touchscreen

Touch screen is the only device which works as both an input and output device. Touch screens works particularly well with menu driven interface viz. ATMs, smart phones, airport information centres. You view the option available on the screen (output) and then use your finger to touch the option that you have chosen (input).

Touchscreens are not suitable for controlling large amount of data.

 

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