WHITE LEDTHE FUTURE LAMP

WHITE LED: THE FUTURE LAMP

A presentation by :Sunanda Chakraborty (Roll # 118)

&Kalyan Bosu (Roll # RL129)Branch: ECESemester: 6

Content:• Introduction • Nobel Award on white LED• Normal LED: Working Principle• Generation of White LED• Manufacturing• Quality Check: Basic Parameters• Uses and Applications• Advantages and Disadvantages• Conclusion

IntroductionLED 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

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.

LED Basics

Working Principal of Basic LEDThe LED is a semiconductor diode that emits light

when current passes through itThe n-side is heavily dopedWhen forward biased, the built-in potential at the

junction is reducedThe e- from n-side get injected into p-side e- combine with the holes resulting in emission of

photons i.e. lightThis effect is called electroluminescence

Colours

Generation Methods of White Light

RGB synthesisUsing Blue LED with phosphor

coating

Other methods include growing zinc selenide (ZnSe) on a ZnSe substrate which simultaneously emitted blue light from diode and yellow light from substrate

Processing

Basic parametersEfficacy 80-160 lm/wattInput power 2-100 wattsColor rendering index (CRI) 65-97Correlated color temperature 2700-8000 kLife time in hours 50,000 hours

Challenges

Electrical compatibilityLEDs run on dc voltageTo run from mains, miniaturized circuitry that

converts AC to DC is provided between supply and deviceThermal management

Heat sinks Fans for cooling

Graphite foam

Thermal Management

Popular Usage of White LED:

Incandescent bulbs

Fluorescent bulbs

High intensity discharge(HID) lamps

Applications Street and outdoor

lighting Architectural

lightning Down lights Freezer case lighting Retail display

lighting Horticulture lighting Portable lighting

AdvantagesSmall in sizeHigh photoelectric conversion

efficiencyIdeal for cycling in lights Longer life time compared to other

light sourcesDo not contain toxic materials such

as mercuryCan be designed to emit light of

intended colourRadiate very little heat Can be dimmed Robust

DisadvantagesExceeds the safety limits of blue-light hazardTemperature dependentCauses more light pollution than other light sourcesVoltage sensitiveHigh initial pricesUnder cool-white LED illumination, the colour of the

objects is perceived differently

Thank You