Output Devices Momina

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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.

Inkjet Printers

TFT Monitors

Dot Matrix Printers

Plotters

CRT MonitorsCl ick for more>>>

Laser Printers

Speakers

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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.

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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 DisadvantagesEasy to move and carry around. Limited angle of viewingProduce 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

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Laser Printers

× 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

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Laser Printers

Advantages DisadvantagesFast 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.

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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.

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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.

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Plotter • 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

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Plotters

Advantages DisadvantagesLarge printouts can be produced

Slow

High quality graphic output.

Filled areas of colour are difficult to produce.Expensive

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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.