COMPUTER OUTPUT DEVICES

1. COMPUTER OUTPUT DEVICES Computer output refers to information out of a computer. Output devices refer to any device capable of presenting/displaying or removing information from a computer.

2. FORMS OF COMPUTER OUTPUT • Softcopy 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.

3. Examples of output devices • Monitors • Data Projectors • Plotters • Facsimile • Printers • Multifunction devices • Speakers • Terminals

4. 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.

6. 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.

8. 3) MULTIFUNCTION DEVICES • Multifunction devices combine the capabilities of a scanner, printer, fax and copying machine.

10. 4) DATA PROJECTORS • Data 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.

12. 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.

14. 6) MONITOR • A monitor is an output device that provides a visual image of both the user’s 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.

15. NOTE THE FOLLOWING • Resolution 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.

16. TYPES OF MONITORS • Flat panel monitors • Cathode ray tube

17. CATHODE RAY TUBE MONITORS • CRT 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.

19. FLAT PANEL MONITORS • These 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.

21. EXAMPLES OF FLAT PANEL MONITORS • Gas plasma • Electroluminescent • Liquid crystal display

22. 7) PRINTERS • Printers 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.

23. TYPES OF PRINTERS • Impact printers • Non impact printers

24. Impact printers • Impact 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.

25. Examples of impact printers • Character printers/serial printers • Line printers/high speed printers • Dot matrix printers

26. Character/serial printers • Character printers are low speed printers that copy the action of the type writers by printing one character at a time. Examples of character printers • Daisy’s wheel • Thimble printers

27. Line printers • Line printers are high-speed printers capable of printing an entire line at one time. Examples of line printers • Chain printers • Band printers • Belt printers • Drum printers

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

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

31. Examples of non impact printers • Inkjet printers • Thermal printers • Laser jet printers

32. Inkjet printers • Inkjet 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.

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

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

38. 8) TERMINAL • Terminals are output devices that connect you to another type of computer called a host computer.