7. Screens as Output Devices

These are devices used to 'see' the results of any processing of any data entered into the computer through any of the input devices described earlier.

1. Liquid Crystal Display (LCD) Screens

• These screens are flat,
• need only a small amount of power to run and can be powered by batteries.
• They do not weigh as much as ordinary monitors. This means they are ideal for use on laptops and palmtop's.

Liquid crystals work by blocking light reflected from behind, so the screens cannot be read in the dark unless they are backlit

Movie: 13. Display Screens

 

 

2. Thin Film Transistor (TFT) Screens

• TFT is a type of LCD screen that has more complex electronics than an ordinary passive LCD.
• It uses arrays of transistors to control backlighting of the screen actively.
• These enable it to display graphics and animations much more clearly and quickly than an ordinary LCD and
• can display moving graphics without ‘shadowing’.

 

 

 

 

3. Cathode Ray Tube (CRT) Monitors or Visual Display Units (VDU)

• Made with Glass tubes these are large bulky units, which use a lot of power to work.
• Although, still very common they are being replaced by more popular flat panel screens.

 

 

 

 

4. Graphics Cards

Today’s applications use a lot of graphics. Even standard applications such as spreadsheets run on operating systems with a WIMP HCI. This means that all applications need graphical items to run, such as windows, icons, and drop-down menus.

Gaming software makes the heaviest demands on the graphics facilities of our computers with its use of three-dimensional graphics and realistic animations.

Graphics cards are designed to support the need for increasingly complex graphics. Like sound cards, graphics cards have their own processor dedicated to producing the graphics and relieving the main system processor of the job.

Graphics cards also have their own memory dedicated to handling the graphic data, relieving the pressure on the system’s main memory. The processor loads in the graphic file, which is made up of binary numbers and then outputs the graphic as a stream of signals to control the output on the monitor.

 

Movie: 14. Graphics Card

 

 

 

What you have to do!

Watch the videos above and in your Word document or your Brain complete the following exercises.

1. What is the difference between an LCD screen and a TFT screen?

2. What features of LCD/TFT screens make them suitable for use on laptops?

3. Why do computers need graphics cards?

4. Why do graphics cards have their own memory and processor?

 

 

What you should be able to do!

1. Explain what the initials VDU, LCD and TFT stand for.

2. List the advantages and disadvantages for each type of display screen

3. Explain the importance of Graphics Cards

 

Continue to 8. Memory (RAM & ROM)