The document provides an overview of light-emitting diodes (LEDs) and liquid crystal displays (LCDs), explaining their mechanisms and applications. LEDs are efficient light sources that convert electrical energy into light, while LCDs utilize liquid crystals to modulate light for display purposes. Both technologies are contrasted in terms of power consumption, response rates, and size options available.

1. LED & LCD
ELECTRONICS AND COMMUNICATION ENGINEERING
POORNIMA INSTITUTE OF ENGINEERING & TECNOLOGY,
JAIPUR
A PRESENTATION ON
SUPERVISED BY:
Mr. Rahul Gupta
Assistant Professor
SUBMITTED BY:
-Madhusudhan
Agarwal

2. What is LED?
 A light emitting diode (LED) is essentially a PN junction
opto-semiconductor device.
 It emits a monochromatic (single color) light when
operated in a forward biased direction.
 LEDs convert electrical energy into light energy.

3. How Does An Work?
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a. When sufficient voltage is applied to
the chip across the leads of the LED,
electrons can move easily in only one
direction across the junction between
the p and n regions.
 When a voltage is applied and the
current starts to flow, electrons in the
n region have sufficient energy to move
across the junction into the p region.

4. How Does A LED Work?
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1.Each time an electron recombines with a
positive charge, electric potential energy is
converted into electromagnetic energy.
2.For each recombination of a negative and a
positive charge, a quantum of electromagnetic
energy is emitted in the form of a photon of
light with a frequency characteristic of the
semi-conductor material (usually a
combination of the chemical elements gallium,
arsenic and phosphorus)..

5. Inside a Light Emitting Diode
1. Transparent
Plastic
Case
2. Terminal
Pins
3. Diode

6. Driving LEDs
Two type of DRIVING LED
 Analog LED Drive Circuits
 Digital LED Drive Circuits
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7. Analog LED Drive Circuit
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8. Digital LED Drive Circuits
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9. Bargraph 7-segment Starburst Dot matrix
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Some Types of LEDs

10. Advantage of an LED
 Efficiency is high
 Small size
 On/Off time is less .
 Slow failure
 Lifetime

11. Applications of an
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• Sensor Applications
• Mobile Applications
• Sign Applications
• Automative Uses
• LED Signals
• Indicators

12. Liquid-Crystal (LCD) Displays

13. 1. 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.
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14. 2. Introduction to Liquid Crystal Displays
 A liquid-crystal display (LCD) is a flat panel display
that uses the light modulating properties of liquid
crystals.
 Liquid crystals do not emit light directly
 It consists of an array of tiny segments (called pixels)
that can be manipulated to present information
 Using polarization of lights to display objects
 Common wrist watch and pocket calculator to an
advanced VGA(video graphic array) computer screen
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15. Different types of LCDs
There are Two type of LCDs available
1.Passive Matrix LCDs
2.Active Matrix LCDs
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16. Active Matrix V/S Passive Matrix LCDs
Active Matrix LCD
 Allow very high resolution
 It isn`t limited to about 50 rows
 Each sub-pixel is individually
controlled by an isolated thin-
film transistor (TFT).
 More use in Laptop & TV
Passive Matrix LCD
 Allow high resolution
 It is usually limited to about 50
rows
 Each sub-pixel is not individually
controlled by an isolated thin-
film transistor (TFT).
 Less use in Laptop & TV

17. LCD Display Technology
Technology Enhancements:
Better color through corrected CCFLs, LEDs
Improved black levels (compensating films)
Higher contrast (pulsed backlights)
Wider viewing angles (compensating films)
Higher resolution (1920x1080)
Improved LC twist times

18. Advantages
 Very compact and light.
 Low power consumption.
 Very little heat emitted during operation, due to low power consumption.
 No geometric distortion.
 Is very thin compared to a CRT monitor, which allows the monitor to be
placed farther back from the user, reducing close-focusing related eye-
strain.
 Can be made in almost any size or shape.
 No theoretical resolution limit.
 Can be made to large sizes (more than 24 inches) lightly and relatively
inexpensively.
.

19. Applications
 Thin Film Transistor (TFT)
 Alpha-numeric display
 Back lighting systems
 For brighter displays

20. Comparison Between LED & LCD
LED
 Power Consumption is less
 Faster response rate time
 Sizes Available
17inches and 70inches.
 Color Accuracy is less
 Cannot be extremely slim
LCD
 Power Consumption is more
 Slower response rate time
 Sizes Available
15inches to 65 inches
 Color Accuracy is more
 Can be extremely slim

21. AND

22. THANKYOUFOR YOUR
PATIENCE….