White LEDs are revolutionizing lighting technology. They last 25 times longer than incandescent bulbs while using less than half the power. Three scientists won the 2014 Nobel Prize in Physics for inventing blue LEDs, an important step in creating white LED lamps. White LEDs work by combining blue LED chips with phosphors that convert the blue light to produce white light. They have many advantages over traditional lighting like longer lifetime, lower heat production, and lower energy use. However, they also have some disadvantages such as higher initial cost and potential for light pollution.

1. WHITE LED
THE FUTURE LAMP
Presented by
G.DHARANIDARAN

2. Introduction
• LED goes to revolutionize the lighting technology of modern
era.
• Fourth and latest generation of light sources
• The white LED lamp is equivalent to 60 watt incandescent bulb
in size and brightness but lasts 25 times longer and runs on less
than 10 watts

3. Noble Prize in Physics in 2014
Isamu Akasaki and Hiroshi
Amano at Nagoya University,
Japan, and Shuji Nakamura of the
University of California at
Santa Barbara have won the
Nobel prize in physics for the
invention of blue light-emitting
diodes – an energy-efficient and
environment-friendly light source.

4. LED Basics

5. Working Principal of Basic LED
• The LED is a semiconductor diode that emits light
when current passes through it
• The n-side is heavily doped
• When forward biased, the built-in potential at the
junction is reduced
• The e-
from n-side get injected into p-side
• e-
combine with the holes resulting in emission of
photons i.e. light
• This effect is called electroluminescence

6. Working Of LED

7. Colours

8. Processing

10. White LED Generated

11. Basic parameters
• Efficacy 80-160 lm/watt
• Input power 2-100 watts
• Color rendering index (CRI) 65-97
• Correlated color temperature 2700-8000 k
• Life time in hours 50,000 hours

12. • Electrical compatibility
LEDs run on dc voltage
To run from mains, miniaturized circuitry that converts AC to
DC is provided between supply and device
• Thermal management
Heat sinks
Fans for cooling
Graphite foam

13. Thermal Management

14. Popular Usage of White LED:
Incandescent bulbs
Fluorescent bulbs
High intensity discharge(HID)
lamps

15. Applications
• Street and outdoor
lighting
• Architectural
lightning
• Down lights
• Freezer case lighting
• Retail display
lighting
• Horticulture lighting
• Portable lighting

17. Advantages
• Small in size
• High photoelectric conversion
efficiency
• Ideal for cycling in lights
• Longer life time compared to
other light sources
• Do not contain toxic materials
such as mercury
• Can be designed to emit light of
intended colour
• Radiate very little heat
• Can be dimmed
• Robust

18. Disadvantages
• Exceeds the safety limits of blue-light hazard
• Temperature dependent
• Causes more light pollution than other light sources
• Voltage sensitive
• High initial prices
• Under cool-white LED illumination, the colour of the
objects is perceived differently

19. Thank You