1. Output Devices

2. Output Devices
The physical parts of a computer that you can touch is the hardware.
A single item of hardware is called a device.
An output device allows data to be displayed or passed out of a computer.

3. Output Devices Printers VDU (Visual Display Unit) Sound Card Speakers
Laser printer
Inkjet Printer
Plotter
VDU (Visual Display Unit)
LCD (Liquid Crystal Display)
TFT (Thin Film Transistor)
Sound Card
Speakers
Graphics Card
Specialist output devices for disabled users & Virtual Reality.

4. Laser Printers Can produce black & white images as well as colour.
Do not use ink!
Use a special powered called toner.

5. Inkjet Printers Quieter than Laser.
High quality prints of both graphics & text.
Particularly good at photographic printouts
Can print on different surfaces – CDs

6. Photo Printing
Inkjet printers are used to print photographs taken by digital camera.
Some have memory card slots so
that photos stored on a card can
printed without having to load the
photos into a computer.

7. Comparing Printers
If you are going to buy a new printer, what criteria should you use to choose?
Resolution
Speed
Cost
Capital Cost
Running Cost

8. Resolution Resolution is how accurate a printer is.
It is measured in Dots Per Inch (DPI).
Laser printers = 300 * 300 dpi to about 2400 * 1200 dpi.
Inkjet printers = 360 * 360 dpi to about 2880 * 270 dpi

9. Speed Speed is measured in Pages per Minute or PPM.
It varies depending on whether you are printing black & white images or colour.
Laser printer are between 4 to 32 PPM.
Inkjet printer are between 2 to 15 PPM

10. Capital Cost
Laser printer can range from under £100 to more than £2000.
Inkjet printer range from £30 to £300.
Note this is one part of the situation – the cost to produce a printout is also very significant – this is called running costs.

11. Running Costs Inkjet Laser Monocrome Colour Cartridge £10 - £15
£15 - £25
Toner
£30 - £50
Up to £200
Number of pages
Up to 8000
Up to 3000

12. Running Costs Laser printer use more electricity than inkjets.
Running costs can increase if labels, envelopes and photo quality paper are used.
Inkjet printers can be bought so cheaply because the makers know people will have to pay for ink.
Petrol = £1.40 per litre. Ink = £1700 per litre!

13. Monitors Accepts a video signal directly from a computer.
Three Main types of monitor are:
Cathode Ray Tube (CRT)
Liquid Crystal Display (LCD)
Thin Film Transistor (TFT)

14. Cathode Ray Tube (CRT)
Large, Heavy, power and
space consuming.

15. Liquid Crystal Display (LCD)
Can have as many as 2.3 million pixels which have to be switched on and off individually.
Used for small, low resolution devices like calculators & watches.

16. Thin Film Transistor (TFT)
This gives improved clarity and colour.
High quality colour displays on laptops & desktops.
Smaller and lighter than CRT
Use less power – good for portable devices
However, they have a limited viewing angle and are expensive to produce.

17. Monitors

18. Speakers
Most computers have built in speakers.

19. Sound Card
Improves the quality of sound outputted from the computer for games, multimedia applications, CDs and DVDs.
Allows sound to be input via a microphone.
The sound card does Digital to
analogue conversion.

20. Graphics Card Controls the quality of the display on a monitor.
Can contain a large amount of RAM.
May have its own processor.

21. Specialist Output Devices
Computers can be used to output voice (speech synthesis).
Useful for users with a visual impairment.
Multimedia projector
Virtual Reality
Users wear a headset with
earphones.