1. Output Devices
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2. What Are Output Devices?
As the name itself suggests, it is a device you can use to output data from a computer.
A variety of different output devices are listed on the next slide.

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CRT Monitors
TFT Monitors
Inkjet Printers
Speakers
Plotters
Dot Matrix Printers
Laser Printers

4. CRT Monitors CRT stands for cathode ray tubes.
Despite the fact that it is the cheapest monitor available it is becoming less popular.
It consists of an electron gun that shoots electrons against phosphor particles.
They are used in environments where space is not an issue.
Advantages
Disadvantages
Cheaper than TFT monitors.
Difficult to life and move around
Produce better quality images as opposed to a TFT
Emit harmful radiation (small quantity)
Screen on the monitor can be viewed from a number of angles.
They have a flickering screen; this can cause headaches and eye strain.
Ergonomic keyboards are now coming into common use due to the increase in number of people who use the computer. Their purpose is to prevent RSI whilst typing. This is aided by the shape of

5. TFT Monitors
TFT stands for thin film transistor. These monitors can also be called LCD’s. LCD stands for liquid crystal display.
The screen consists of thousands of miniature transistors. These transistors are activated by the processor. Each pixel is formed from RGB (Red, Green and Blue).
Used when only 1 person needs to see the screen.
Advantages
Disadvantages
Easy to move and carry around.
Limited angle of viewing
Produce less glare (reduced eye strain)
Inconsistency of colour when viewed from different angles.
Emits less radiation as opposed to CRT
Videos may blur
More expensive than CRT

6. Laser Printers Advantages and Disadvantages
High quality hard copies are produced.
How does it work?
Laser changes the charge on the drum for each dot.
Electrically charged toner is attracted to the oppositely charged dots.
The paper then presses against the toner-coated drum
This then outputs with the pattern of dots required.
Page is only printed after whole documents has been stored in buffer.
Used usually in places where silence is required.
Advantages and Disadvantages

7. Laser Printers Advantages Disadvantages Fast output
Limited in size of paper.
Running costs are cheaper
Initial costs are high.
Large print jobs can be done quickly
First page may be slow to print.
Quality is high
Toner cartridges last longer; so laser printers can be used on longer print runs.

8. Inkjet Printers Ink is forced out of a nozzle directly onto the paper.
Weighs less than a laser printer
Printout is produced little by little as it receives the signals from the computer.
They are especially useful in those places where high quality is required and speed is not an issue.
Advantages
Disadvantages
High quality printout
They are slow if you need to print more than one page.
Fast if you are only printing one page
More expensive to run because the ink cartridges don’t last very long.
Cheaper than other printers
Long print jobs may be difficult because the ink cartridge may run out.
Are more mobile as opposed to other printers.

9. Dot Matrix Printer Impact printers. How does it work?
The print head (usually made up of several pins) pressing against a carbon ribbon onto paper.
Ink from the ribbon is the visible on the paper.
They are commonly used in noisy industrial environments.
Advantages
Disadvantages
Are able to work in environments where the laser and ink printer would not last.
Not suitable for office environment as they are noisy.
Produce carbon copies.
More expensive than inkjets
Running costs are low.
Slowest type of printer.
Continuous print jobs are more easily managed.

10. Plotter Advantages and Disadvantages
Its is able to produce hard copies but is not limited to the size of the paper.
How does it work?
Ink is placed on a roll of paper rather than individual sheets.
There are three types:
1- Pen plotter : prints to paper using different colour pens. It relies on the computer to control the movement of the pen and paper.
2- Electrostatic plotter:
3- Inkjet plotters
They are used to produce printouts of graphs and blueprints.
Advantages and Disadvantages

11. Plotters Advantages Disadvantages Large printouts can be produced Slow
High quality graphic output.
Filled areas of colour are difficult to produce.
Expensive

12. Speakers Output sound that is produced or is stored by the computer.
They are required to play sound files attached to presentations or websites.
It is a very important part of a home entertainment system.