OUTPUT DEVICES
These are hardware components used to obtain results from computer after processing. They convert data from machine-readable format into human readable format. Examples of output devices are monitor, printer, speaker, projector, plotter, etc.
MONITOR
This is an output device that displays the result of processing on the screen. It resembles a T.V set and it’s also called a Visual Display Unit (VDU) or simple the screen. The output obtained from a monitor is called the softcopy since this output can only be seen.
Types of monitors
Monitors can be classified using two categories. These are:
- The Shape
- The number of colours it displays
The shape
- CRT (Cathode Ray Tube) monitor
- LCD (Liquid Crystal Display) monitor
CRT Monitor
These are very bulky but are normally expensive than LCD monitor. They are more precise in colour presentation.
LCD Monitor
These have flat screen and are lighter in weight but more expensive. They are commonly used in laptop, notebooks as well as desktop computers. Based on the colour, there are two major types – monochrome and colour monitor.
Monochrome Monitor
These display one colour at the background and one colour at the foreground. The colour can be black and white, green and black or amber and black. There is a special type of monochrome monitor capable of displaying different shades of gray.
Colour Monitors
These monitors display 16 to about 1 million different colours. They are sometimes called RGB monitors because they accept three separate signals – Red, Green and Blue.
The different types of colour monitor are:
- Colour Graphic Adapter (CGA) which displays 4 colours.
- Enhanced Graphic Adapter (EGA) which support 16 colours
- Videos Graphic Adapter (VGA), which support 16 to 256 colours
- Supper Video Graphic Adapter (SVGA), which supports 256 and more colours.
PRINTERS
A printer is an output device that produces output on paper and other similar printing media. The output of a printer is called hardcopy.
Types of printers
- Impact Printers
- Non-Impact Printer
Impact Printers
These are the printers capable of creating images by using some mechanism to physically press an inked ribbon against the page, causing the ink to be deposited on the page in the desired shape. They have physical contact with the paper when printing. They are noisy printers.
Examples of impact printer are daisy wheel, dot-matrix, band printer, golf-ball printer, chain printer, etc.
Non-Impact Printer
These are printers that operate without direct physical contact between the printing mechanism and the paper. They spray ink on a paper or use photo technology in printing images. Examples are inkjet printers, thermal printer, laserjet printers, sparkjet, printers, etc.
Non-impact printers are not as noisy as impact printer when printing.
Other printer types are:
- Character printer
- Page printer
- Line printers, etc.
PLOTTERS
These are output devices that print vector graphics. They draw pictures on a paper using a pen. Plotters are used in applications such as Computer-Aided Design. They are used for producing complex graphical output in form of graphs. They are also used in scientific researches, engineering and management information system (MIS). Examples of plotters are electrostatic plotters, cutting plotters, pen plotters, etc.
SPEAKERS
These are also called sound blaster. They are used to obtain sound or audio output from the computer. Speakers are connected to sound cards or sound adapter on the motherboard. The sound card translates digital information. To play sound or audio, the sound card receives digital information from a stored file and turns it into an electrical signal. This signal is the sent to the speaker which produces the sound.
PROJECTOR
This is an output device that projects image into a surface or a projection screen. It is used to show the result from the computer on a large flat screen. A projector is usually used in meetings, workshops, seminars, conferences or to make presentations because it allows large to be shown on the screen with which the display is available to a large audience. Projectors can sometimes be used in place of monitors.
MICROFILM
This is used to store voluminous output that will require too much space if stored normally. Such outputs are stored on film by the processor in a reduced format. The microfilm machine or reader can then be used to later search for the required information and print it out.
Types of Microfilm
This is used to store voluminous output that will require too much space if stored normally.
- Silver halide film
- Vesicular film