COMPUTER HARDWARE

COMPUTER OUTPUT DEVICESComputer output refers to information out of a computer.

Output devices refer to any device capable of presenting/displaying or removing information from a computer.FORMS OF COMPUTER OUTPUTSoft copy is the information/data displayed visually on the screen or is audio or voice form such as speech or music and this kind of output is not tangible.

Hard copy refers to information/data that is in a permanent form that is in print out form. Hard copy is tangible.

Examples of output devicesMonitors Data ProjectorsPlotters Facsimile

Printers Multifunction devicesSpeakers Terminals

1) SPEAKERS Speakers are audio output devices that produce sound signals from a computer.

The most widely used audio output devices are speakers and headphones.

Audio output devices are used to play music and communicate information from the computer system to users.

2) FAX MACHINE (FACSIMILE) A facsimile machine is an output device that transmits and receives documents over telephone lines and prints the documents on paper.

3) MULTIFUNCTION DEVICESMultifunction devices combine the capabilities of a scanner, printer, fax and copying machine.

4) DATA PROJECTORSData projectors are output devices that take images displayed on the computer screen and project/cast them on a larger screen so that people can see the images clearly.

5) PLOTTERS Plotters print their output by moving a pen across the surface of a piece of paper.

Plotters are suitable for architectural drawing, in engineering applications and map making.

Plotters are used to draw lines using a pen; as a result, they can produce continuous lines.

6) MONITORA monitor is an output device that provides a visual image of both the users input and computer output.

A monitor displays information on its screen thus helping the user to monitor operations carried out by the computer.

Monitors (Visual display terminals/visual display units) are the most commonly used output devices.

Monitors present visual images of text and graphics.

NOTE THE FOLLOWINGResolution is the clarity and sharpness of images formed on the monitor.

Images are formed on the monitor by a series of dots or pixels (picture elements).

Dot pitch is the distance between each pixel.

Refresh rate indicates how often a displayed image is updated and redrawn on the monitor.

TYPES OF MONITORSFlat panel monitors

Cathode ray tube

CATHODE RAY TUBE MONITORSCRT is the most common type of monitors for the office and homes. Their primary advantages are: can produce fast and rich colour output, can be viewed from a very wide angle and low cost.

Their major disadvantages are that they are bulky, consume a lot of power and occupy a considerable amount of space on the desktop.

FLAT PANEL MONITORSThese monitors are much thinner and require less power to operate than cathode ray tubes.

Flat panel monitors require less power to run than CRTs however are more expensive than CRTs and can only be viewed from a very narrow angle.

EXAMPLES OF FLAT PANEL MONITORSGas plasma

Electroluminescent

Liquid crystal display

7) PRINTERSPrinters are output devices that produce text and graphics on a physical medium like paper.

Printer output is often called hard copy.

Printers are categorized by how images are formed that is whether or not the image is formed by physical contact of the print mechanism with paper.

TYPES OF PRINTERS Impact printers

Non impact printers

Impact printersImpact printers are a class of printers that work by banging a head or needle against an ink ribbon to make a mark on the paper.Impact printers use pins or hammers which hit a ribbon to transfer images to paper.

Examples of impact printersCharacter printers/serial printers

Line printers/high speed printers

Dot matrix printers

Character/serial printersCharacter printers are low speed printers that copy the action of the type writers by printing one character at a time.

Examples of character printersDaisys wheelThimble printers

Line printersLine printers are high-speed printers capable of printing an entire line at one time.

Examples of line printers

Chain printersBand printersBelt printersDrum printers

Dot matrix printersDot matrix printers form characters and images using a series of small pins on a print head.

Non impact printersNon impact printers are printers that use chemicals, lasers or heat to form the images on the paper.

Examples of non impact printersInkjet printers

Thermal printers

Laser jet printers

Inkjet printersInkjet printers spray ink at high speed onto the surface of the paper.

This process produces a letter quality image and permits printing to be done in a variety of colours.

Thermal printersThermal printers use heat elements to produce images on heat-sensitive paper.

Laser printersLaser printers use a laser light beam to produce images with excellent letter and graphics quality.

8) TERMINALTerminals are output devices that connect you to another type of computer called a host computer.