output device

Output Devices

These are devices used to 'see' the results of any processing of any data entered into the computer through any of the input devices described earlier.

1. Printers

Computers were supposed to bring about the dream of a 'paperless office'. This now looks very unlikely to happen because paper has got some advantages over computers when looking at information.

Advantages of Paper

1. It is very portable. The information on a sheet of paper is easily passed around, and many people can look at the information at the same time.
2. It is cheap. Initial costs of computers means there is no comparison with the cost of using paper.
3. Not everyone has computer equipment to view information, or it may
   be difficult to use computers in some situations.

Paper copies, or hard copies, of information will always be needed. Printers (and plotters) are used to produce these hard copies. The main different types of printer, and how they are compared against each other, are explained below.

a. Laser Printers

This type of printer is the main one used in schools, offices and industry because it produces high-quality printouts very quickly, with good resolution.

How it works?

• It uses a laser to make a negative electrical image of the page on a positively charged drum, which then picks up positively charged toner.
• The drum rolls over the paper and the toner is heated to print on to the page. The toner cartridge gives many copies before needing replaced keeping running costs down.
• Laser printers are generally more expensive than inkjet printers, but their running costs are lower.

b. Inkjet Printers

:Basic models of this type of printer are cheap to buy, and let you print in colour.
The quality of the best inkjet's can be very high and can be used for photographs.

• Inkjet printers spray special ink on the paper to form characters and graphics.
• The cost of replacing ink cartridges can be high with this type of printer because they need replaced frequently.
• They print quite quickly, but can be quite slow when printing graphics.
• They are slower than laser printers.

2. Plotters

Plotters are large printer type devices. Instead of using ink cartridges, plotters use pens to draw the output on to paper. With different coloured pens, plotters can produce colour output.

Plotters are capable of producing very accurate drawings and plans. They are most often used in computer aided design (CAD).

The picture partly shows some 'blue prints' produced by a plotter.

3. Sound Card and Speakers

A sound card captures sounds and changes them into digital binary numbers that are stored as files in your computer.

When outputting sounds the sound card reverses the process and changes binary data held in the sound files into analogue signals that are used control the speakers attached to the computer. Speakers convert analogue audio signals into the equivalent air vibrations in order to make audible sound. A pair of speakers plugs into the computer’s sound card.

A good sound card is necessary to get the best gaming experience.

4. Screens and Monitors

Screens are the most common of output devices. They show what's going in the computer. There are really three main types.

1. Liquid Crystal Display (LCD) Screens.
2. Thin Film Transistor (TFT) Screens.
3. Cathode Ray Tube (CRT) Screens