Output devices

Monitor

Monitors are also known as visual display unit (VDUs). They come in different styles and quality levels. Screen colour quality, resolution and clarity are just some of the features that affect how desirable a particular monitor is to you.

Picture elements

Although the picture on a computer monitor may look sharp and clear, it is made up of many illuminated dots known as picture elements or pixels. The dots are usually so tiny that you would not normally notice them individually – you just see the whole picture. If you could actually see the picture elements, the picture would look jagged.

Advantages of monitor screens

-Enables the use of a graphical user interface. -Interactive, on-screen use of a computer is more natural and intuitive than programming.

Disadvantages of monitor screens

-Screen size can limit the extent and detail of what can be seen. For example, it is possible to refer to several printed pages at the same time. It could be much more difficult to arrange this on a monitor. -Screen displays can be difficult to read for people who have impaired sight

Types of printers

● Dot matrix ● Inkjet ● Laser ● 3D

Dot matrix

Dot matrix printers usually strikes through an inked ribbon, making marks on the paper.

Inkjet printers

Inkjet printers use tiny dots of ink sprayed onto the paper, forming the shapes of characters and pictures.

Laser printers

Laser printers use laser light to make patterns of ink on a drum. This drum then transfers the ink to the paper, and finally a heating process fuses the ink to the paper.

Advantages of printers

● Printed output can be viewed without the need for a computer. ● Many people and organizations still use paper-based communications and similar legacy methods

Disadvantages of printers:

● Printing is slow and expensive compared with electronic communications and storage. ● Paper is bulky and deteriorates in storage. ● Printed materials are more difficult to access and distribute. For example, printed photographs can be viewed by a limited number of people compared with digital photographs displayed on a TV screen, and it is more difficult and expensive to send copies to others

Multi-function printers

Printers are now being built in combination with scanners, and sometimes with fax machines. Combining a printer with a scanner produces the effective functionality of a photocopying machine, as well as providing the separate functions of scanning and printing.

Advantages of multi-function devices

● A multi-function device takes up much less space on the desktop than the individual devices it replaces. ● A multi-function device is usually less expensive to buy than all the individual devices it replaces. ● A multi-function device will be used more before it becomes obsolete. ● A multi-function device can be replaced more frequently, having provided good value, so that more modern technology is available for use.

Disadvantages of multi-function devices:

● If part of the device develops a fault, all the functions may be unavailable. ● Only one person at a time can use a multi function device.

Plotter

A plotter draws lines on paper using differently coloured pens. In a flatbed plotter, the paper is held still while the pen moves. Plotters are frequently used in computer-aided design.

Advantage of plotters

-Much larger and longer sheets are printed.

Disadvantage of plotters

-Printing is very slow -Plotters are usually more expensive than printers

Data projector

A multimedia projector or data projector projects an image that would normally be displayed on a computer screen onto a larger, separate screen. This allows the image on the screen to be shared with an audience in a large room.

Speakers

Speakers are output unit of sound. This is used to play music, to make telephone calls using VoIP, to listen to voicemail, to play video and DVDs for entertainment or education and to listen TV and radio. Speakers are also needed for speech synthesis, where a computer reproduces human speech.

Advantages of speakers

-They allow computer systems to be used for a wide range of multimedia applications. -Interaction with a computer using voice recognition and speech synthesis is more natural and intuitive than programming.’

Disadvantages of speakers

-Applications that use speakers can be difficult to operate for people who have impaired hearing. -Voice recognition systems can be difficult to set up and use