1. SPECIAL THANKS
First of All I am greatly thanks to ALLAH Whose give me ability to courage and power to complete the presentation without blessing mercy and favor I am not able to do this work.

2. Topics
Liquid Crystal Displays ( LCD )
Light Emitting Diode ( LED )

3. What’s Liquid Crystals (LC)
intermediary substance between a liquid and solid state of matter. e.g. soapy water
light passes through liquid crystal changes when it is stimulated by an electrical charge.

4. Introduction to Liquid Crystal Displays
Consists of an array of tiny segments (called pixels) that can be manipulated to present information.
Using polarization of lights to display objects.
Use only ambient light to illuminate the display.
Common wrist watch and pocket calculator to an advanced VGA computer screen

5. Operating Principle
The parallel arrangement of liquid crystal molecules along grooves
When coming into contact with grooved surface in a fixed direction, liquid crystal molecules line up parallel along the grooves.

6. Molecules movement . Operating Principle
Offline (no voltage is applied)
Along the upper plate : Point in direction 'a'
Along the lower plate : Point in direction 'b‘
Forcing the liquid crystals into a twisted structural arrangement. (Resultant force)

7. Operating Principle Light movement Offline (no voltage is applied)
Light travels through the spacing
of the molecular arrangement.
The light also "twists" as it passes
through the twisted liquid crystals.
Light bends 90 degrees as it
follows the twist of the molecules.
Polarized light pass through the
analyzer (lower polarizer).

8. Operating Principle Molecules movement Online (voltage is applied)
Liquid crystal molecules straighten
out of their helix pattern
Molecules rearrange themselves
vertically (Along with the electric field)
No twisting thoughout the movement
Forcing the liquid crystals into
a straight structural arrangement. (Electric force)

9. Advantages of LCD Technology
Energy efficient, low-power
Excellent contrast
Lightweight and compact
Sharp resolution
Superior resolution
Used in battery-powered electronics
Uses a smaller pixelated format

10. Disadvantages of LCD Technology
The color and contrast from various viewing angles is inconsistent
Features poor black on dark imagery
Pixel-based display may be stuck on screen
Fixed resolution
Newer technology costs more
Imagery not as good with analog interface

11. Light Emitting Diode ( LED )

12. What is an LED?
Light-emitting diode
Semiconductor
Has polarity

13. Negative electrons move one way and positive holes move the other way
LED: How It Works
When current flows
across a diode
Negative electrons move one way and positive holes move the other way

14. Therefore when a free electrons falls it losses energy
LED: How It Works
The wholes exist at a lower energy level than the free electrons
Therefore when a free electrons falls it losses energy

15. LED: How It Works
This energy is emitted in a form of a photon, which causes light
The color of the light is determined by the fall of the electron and hence energy level of the photon

16. Inside a Light Emitting Diode
Transparent Plastic Case
Terminal Pins
Diode

17. Kinds of LEDs

18. Benefits of LED Lighting
Long Life
Energy Efficiency
Ecologically Friendly
Durable Quality
Design Flexibility
Light Dispersement
Low-Voltage

19. THE END