LED TECHNOLOGY FOR WONDERING FUTURE(PPT)
- 1. PREPARED BY: UNDER THE SUPERVISION OF: DEPARTMENT OF ELECTRICAL ENGINEERING ER. ABHINAB KUMAR (ASSISTANT PROFESSOR) RAHUL KUMAR BACHELOR OF TECHNOLOGY ELECTRICAL ENGINEERING (3RD YEAR) ROLL NO:1473420034 A PRESENTATION ON LED TECHNOLOGY RAJKIYA ENGINEERING COLLEGE BANDA
- 2. •ABOUT SSL •INTRODUCTION •CURRENT TECHNOLOGY •CONSTRUCTION •HEAT ISSUES •LED COLOUR •PHOSPHOR TECHNOLOGY •SPECTRAL DISTRIBUTION OF WHITE LIGHT •LED MANUFACTURING STAGES •LEAD USEFUL CHARACTERICTICS •LEAD SYSTEM DESIGN •APPLICATIONS •CONTROLLABILITY •THE FUTURE •DISADVANTAGES •CONCLUSION
- 3. What is Solid State Lighting •Heating up bits of wire Conventional Methods of converting electrical energy to light •Passing Electricity through gas at near vacuum •Passing Electricity through gas above atmospheric pressure
- 4. How About LED’s •Passing Electricity through small amounts of crystalline solids •Solid State device Works well with other semiconductors •Initially used for panel indicators •Discovered in 1962 by Nick Holonyak •In 1963 he predicted white LEDS with 10X efficiency of Incandescent
- 5. Early LED colour •Initially red mass produced from 1969 •GaAsP Gallium Arsenide Technology produced red, amber and yellow early green produced by IR and phosphor •GaAIA Gallium Aluminum Arsenide High brightness red LEDs from 1984 •InGaN Indium Gallium Nitride Technology produced blue and green •Allowed development of White LED
- 6. Current Technology •Based on InGaN and A AnGaP •Many colours possible •Colour varies with growth temperature of active layer •Efficiency drops in Green •Different compositions behave differently •Reds and ambers have shorter life and greater colour shifts Blues more stable
- 7. Construction of LEDs •Standard 5mm LED •Epoxy body sometimes coloured •Leads identified for polarity •Reflector maximises light output •Die, semiconductor that emits light
- 8. Construction of LEDs •High output LEDs •Large die with reflector •Mounted to Slug heat sink •Leads exit to side clear of light path •Moulded lens gathers and directs light •Various distribution patterns •Many different packages
- 9. LED Colour •Each type of LED emits light in a narrow band width •Good for saturated colour •Limited for RGB mixed white
- 10. White LEDs •Fluorescence; uses blue die with phosphor •Combination of Blue from die and Yellow from phosphor gives visual white Colour not even across LED Warmer colours less efficient
- 11. Phosphor technology •Best is Itrium Aluminium Garnate Cerium •Produces broad spectrum yellow •90% efficient converting blue to yellow •Deficient in Red •Strontium Sulphide Europium •Produces increased red •Much less efficient •Can create pink tinge in 2700K range •Importance of even thickness Consistent colour •Match binning of phosphor with LED •Recent development of phosphor wafers or better control of thickness
- 12. Spectral Distribution of White
- 13. White Light LEDs •Research goal to create white light directly from die •ZnSe (Zinc Selenide) is a candidate technology not high output •Development as Zinc Oxide nanostructure semiconductor RGB
- 14. LED Manufacturing Stages •Reasons for product variation •The Wafer •The Die •The Package
- 15. The Wafer •Disk of the crystalline material that forms semiconductor •Grown on mineral substrate: Epitaxy Saphire, Silicone Carbide 2” or 6” diameter Aim to use 12” Silicone for economy •Tightly controlled conditions to achieve uniform result •First layer grown at 1000°C •Second at 700°C •Final at 1000° C •Risk of changes to middle layer Substrates flex •Varies thickness of layers •Process takes 5 to 6 hours
- 16. The Die •Wafer literally “diced” like carrots! •Dies “binned” •For colour (chromaticy) •For forward voltage •For output
- 17. Packaging •Connections made to die •Die inserted in package •Many dies in same package •Device tested for: forward voltage colour (chromacity) lumen output LEDs then Binned
- 18. Binning •Much discussed aspect of LEDs •At end of production line measurements made fraction of a second device at room temperature 25°C fully automated process First stage of quality control •Possibly the most important aspects tested: Colour Lumen Output Forward Voltage
- 19. Heat Issues •Temperature in die determines LED survival determines operating life determines light output determines efficiency •Higher the temperature lower light output lower the efficiency •Critical temperature much lower than conventional lamps •LED internal temperatures 100°C to 150°C absolute maximum depends on chip
- 20. LEDs‐ Useful Characteristics • Electrically Efficient • Long Lifetime • Low radiated heat • Emit pure colors without filters (more efficient) • Intensity can be varied over operational range with little spectral shift • Rapid on/off capability • Small size allows unprecedented flexibility in application • Rugged – Solid state – Not damaged by repeated on/off cycles – No fragile glass envelope • No hazardous materials (e.g. mercury)
- 21. LEDs‐ Useful Characteristics ‐Can Match Spectrum to Application
- 22. LEDs‐ Useful Characteristics •Highly flexible Advanced Lighting Control Systems HELIAC adaptive lighting system
- 23. LED System Design “Standard” 5mm Standard surface‐mount (SMT) High‐power emitter types Pre‐packaged high‐power arrays
- 24. LED System Design Optics – Commercially available – Custom / application specific •Diffusers •Lens •Collimators •Remote Phosphor
- 25. LED Mechanical Components & Configuration Power and signal distribution Arrays of LEDs (actively or passively cooled Optics and protection mechanisms Control box (many configurations possible)
- 26. APPLICATIONS •LED Plant Lighting in Space •System Configuration; Overhead Bars •Large Sole Source Lighting Arrays •IN DOMESTIC USES •IN AUTOMOBILES •FOR INDICATION
- 27. LED Plant Lighting in Space Astroculture‐4 1994 First LED plant lighting in space Veggie‐01 2014
- 28. System Configuration; Overhead Bars
- 29. Large Sole Source Lighting Arrays
- 30. Controllability •LEDs easy to control - they are an electronic component! •Facades of light easy to do Imagery allows architecture to change day and night •Reactive and interactive surfaces, walls and ceilings •LEDs deliver colour easily and efficiently compared with other light sources
- 31. The Future •Field of light products much more likely to be successful •optimizes use of LED and existing backlight technology •opens possibilities for fittings not to be rectangular or circular •no longer are fitting sizes restricted by set dimensions of lamps •First product recall, High efficiency LEDs recalled from fittings manufacturers •Production halted for 4 months •Line voltage LEDs •Seol semiconductor Acriche 2W & 4W 120V and 230V warm and cool white 30LmW to 40 LmW headline efficacy •No transformer losses •Simplified Wiring
- 32. The Future •Multi colour chips on same wafer - White by color mixing Complex circuits on chip - •Zinc Oxide Nanotechnology Semiconductor •LED materials can also produce energy from light •LED detectors / emitters •Development of Photovoltaics using InGaN junctions
- 33. Environmental Issues •Price per lumen of LED exceeds all other light sources •Revenues consumed by continuous development •Additional cost must be argued on basis of:- low maintenance low energy in use System has finite life Not always determined before installation •Whole system will require replacement at end of life •- Issues with WEEE for disposal and re- cycling
- 34. • LEDs are currently more expensive, price per lumen, on an initial capital cost basis, than more conventional lighting technologies. • LED performance largely depends on the ambient temperature of the operating environment. Over-driving the LED in high ambient temperatures may result in overheating of the LED package, eventually leading to device failure. Adequate heat-sinking is required to maintain long life • LEDs must be supplied with the correct current. This can involve series resistors or current-regulated power supplies
- 35. Conclusion •LEDs increasingly common in lighting applications •They remain the most complex light- source to design and specify •Manufacturers are guardians of knowledge •Big players potential to monopolize design to installation •Professional Lighting Design community must learn more •Personal research and demanding information from suppliers •Professionals must determine the suitable light-source for every application •LEDs will never be the universal light- source for all applications
- 36. Thank you
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