PROCESSORBacking Storage Main Memory

Output Devices

Input Devices

Output DevicesTranslates signals from the computer into a human-readable form.

• Printers

• Plotters

• Monitor

• VDU

• Liquid Crystal Display (LCD)

• Thin Film Transistor (TFT)

• Sound Card

• Graphics Card

• Specialised output device for disabled users and virtual reality

• Output devices for Multimedia

Printers

A device which is used to produce a printout (Hard Copy) for the output from a computer.

• Laser Printer

• Inkjet Printers

• Photo Printers

Laser Printer

Use a special powder called toner to produce the image on the paper. A laser beam is used to project the image of the page to be printed onto a cylinder known as a drum.

Inkjet Printer

A type of printer that sprays tiny streams of quick-drying ink onto paper.

The number of holes on the print head determines the printers resolution.

Photo Printer

photo printer is a printer (usually an inkjet printer) that is specifically designed to print high quality digital photos on photo paper. These printers usually have a very high number of nozzles and are capable of printing droplets as small as 2 picoliters.

(trillionth part of a litre)

Laser vs Inkjet

Resolution

A printers accuracy is known as its resolution. Resolution measured in dots per inch (dpi).

Inexpensive colour laser printer will be between 1200 x 600 dpi to 2400.

And a higher-end colour laser will have a resolution between 2400 x 1200 dpi to 2400.

Inexpensive inkjet printer will be between 1200 x 1200 dots per inch (dpi) to 2400

And a higher-end inkjet printer will have a resolution between 2400 x 1200 dpi to 4800.

Laser prints from 4 to 32 ppm

An inkjet prints from 2 to 15 ppm

A lasers printer ranges from £100 - £2000.

Toner can range from £30 - £200 (3000 – 8000 pages)

An inkjet ranges from £30 - £300.

Ink cartridges range from £10-£15 (500 – 900 pages)

Cost

Capital cost is how much it cost to purchase the printer. Running cost is how much it costs to use the printer.

A lasers printer ranges from £100 - £2000.

Toner can range from £30 - £200 (3000 – 8000 pages)

An inkjet ranges from £30 - £300.

Ink cartridges range from £10-£15 (500 – 900 pages)

Plotter

A printing device that draws images on paper using ink pens or pencils.

Plotters are capable of producing very accurate large scale drawings and are most often used in computer aided design (CAD).

Monitors

Monitor accepts video signals directly from the computer and displays the output on a screen.

A high resolution monitor will be able to show very fine detail on the screen compared to a low resolution.

Types of monitors:

Cathode Ray Tube (CRT)

Liquid Crystal Display (LCD)

Cathode Ray Tube (CRT)

Most common type of monitor. The electron gun in a video display monitor that generates the focused beam that creates an image on the monitor's screen.

Liquid Crystal Display (LCD)

Consists of thin layer of fluid sandwiched between two sheets of plastic. Complicated wiring is used to apply voltage to different parts of the screen.

Thin Film Transistor (TFT)

A type of LCD flat panel display screen in which each pixel is controlled by one to four transistors.

The TFT technology provides the best resolution of all the flat panel techniques, but it is also the most expensive. TFT screens are sometimes called active matrix LCDs.

Advantages LCD

• LCD are smaller and lighter. (Portable)

• LCD use less power (15-20 watts) Ideal for laptops and palmtops.

• LCD do not flicker or give out static electricity or any other type of radiation.

• Do not suffer reduction in viewable size – 17 inch LCD screen has full view of 17 inch.

Loudspeakers

Most computers have built-in loud speakers or can be connected to one or more loudspeakers.

Sound Card

Sound is analogue in nature, it is continuously varying quantity. Computers work in digital quantities. In order to output sound from a computer the sound must be changed from digital to analogue.

This process is called digital to analogue conversion. (DAC)

Speakers would be plugged into the sound card

socket.

Graphics Card

Device which controls the quality of output on a monitor.

Graphic card contain a large quantity of RAM and can support different types of screen resolution.

Monitor would be plugged into the socket

Specialised user interface

Questions

Internet cafe

1. Jill has some systems set up with voice output capability. Describe a situation where this might be useful for a customer to use.

2. What output device is required for voice output?

3. What does LCD stand for?

4.What does TFT stand for?