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Lighting with Leds: the Elephant in the Room Problem

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Lighting with Leds: the Elephant in the Room Problem Lighting with LEDs: The elephant in the room problem Watch Read Listen Lighting with LEDs The elephant in the room problem Joe Fjelstad, Verdant Electronics It has been estimated in some At over 125 years old, incandescent light- ment instituted a $10 million “L Prize” for studies that more than half of the ing persists; however, incandescent bulbs an energy-efficient replacement for the waste most of the electricity used in their 60-watt bulb, offering added weight to the total energy produced in the US is operation because unfortunately most of perceived importance of efficient lighting wasted due to inefficiencies includ- the energy used with the revered technol- solutions to the nation’s future. The prize ing waste heat from power plants, ogy is turned into heat rather than light. was awarded to Philips in 2012, whose Incandescent lights produce only 10-20 lamps in a specialized test configuration vehicles and perhaps surprisingly, lumens per watt whereas the present day showed no appreciable drop off in lighting light bulbs. In the US alone, light- alternative competitive solution, the com- quality over 25,000 hours of testing . ing consumes approximately 12% pact florescent light (CFL) can produce 50-90 lumens per watt. of the total energy used. This inef- Dealing with challenges and With an appreciation of this wasteful change ficiency is not insignificant, and situation and to encourage energy effi- Creating good alternatives to the time-hon- it has in the last decade become a ciency, the United States Congress passed ored incandescent light bulb has been more a law in 2007 mandat- difficult than expected, target for governments and private ing that bulbs produc- sector entities around the globe. especially for the very ing 100 watts worth The supporting bright 100-watt bulbs. Currently there are efforts under- of light meet cer- Part of the problem is tain efficiency goals, electronic that these new bulbs way to eliminate one of the longest beginning in 2012. lived of one of the most important have to fit into table Because conventional assemblies are lamps and ceiling fix- inventions of all time, incandes- light bulbs cannot tures designed for cent lighting technology. meet those goals, the older technology. CFLs law is poised to pro- proving to be a has been a “low hang- hibit either making ing fruit” alternative or importing them. weak link. as a replacement, but The same rule will they have drawbacks. start apply to remain- They contain a small amount of toxic mer- ing bulbs 40 watts and above in the year cury vapor, which can be released to the 2014. Moreover there have been proactive environment if they break or are improp- efforts at the state level in the promotion of erly thrown away. They last longer than more energy efficient lighting. For example, traditional bulbs but not as long as LEDs. California has already banned stores from Moreover, brighter models of CFLs are restocking 100-watt incandescent bulbs. bulky and may not fit in existing fixtures, While CFL has been popular from an and users have expressed frustration with energy savings standpoint, the lamps have the fact that they start off dim and do not the disadvantage of requiring use of mer- provide full luminosity immediately. cury to operate making them a potential Another new lighting technology of environmental hazard both in home use some growing interest is organic light- and in disposal. As a result, light emitting emitting diodes, or OLEDs. However diode (LED) lighting technology which OLED technology has had problems reach- has been developing at a rapid pace over ing mass production. OLEDs do have some the last several years, is proving a very effi- attractiveness for certain applications as cient solution capable of producing even they can provide light in the form of glow- more light than CFLs at lower wattage. ing sheets or tiles, rather than the “pinprick” The energy savings that could be realized light sources, typified by LEDs. OLEDs are by simply replacing even all 40 watt incan- currently used to provide the vibrant color descent bulbs with 10-watt LED bulbs is screens for smart phones and can pro- clearly appreciable, and thus to stimulate vide localized bright light, as anyone who LED development, the federal govern- has used a “flashlight” application on their www.globalledoled.com Global LED/OLED Supplement — Autumn 2013 – 51 Lighting with LEDs: The elephant in the room problem light is provided by means of light emitting diodes (LEDs), are likely to dominate the lighting market in the coming years. With continuing improvements in LED tech- nology at the chip, packaging and phos- phor development levels, it is anticipated that the price and performance of LEDs will soon match that of current bench- mark energy efficient technologies such as compact florescent lamp technology. However, the reasons for using LED light- ing elements are not limited just to energy efficiency, lighting maintenance is a big element of cost in both public and private sectors when lights unpredictably burn out. This is a primary reason for the increase in traffic signals being converted to LED technology. This is tied to their prospective longevity. LEDs have been proven capable of achieving operational longevities of up to 70,000 hours (the L Prize was limited to 25,000 hours). The elephant in the room However and most unfortunately, the sup- porting electronic assemblies that are com- bined with the LED lamps to transform nominal line alternating current (AC) Separating the electronics which convert AC to DC from the LED lamp assembly could signifi- commercially used voltages in the homes cantly extend the life of the LED lamps and could as well open doors to a wide range of new around the world (e.g.,110V to 250V) into LED lighting possibilities. lower direct current (DC) voltages (e.g., 3V to 5V) required to operate LEDs are prov- smart phone can attest. Unfortunately, bigger the problem is. The most powerful ing to be a weak link and they are com- making OLEDs that are big, bright, cheap pear-shaped LED bulbs in stores today, the monly failing well in advance of the LED and long lasting enough for use as light type that mimic traditional bulb design lamps. They are in effect the “elephant in the sources has proved difficult. This is in part and which fit into existing lamps sockets, room” that gets very little discussion. Thus due in part to the fact that they use chemi- produce light equivalent to a 60-watt bulb; when the transformer fails for any reason, cals that are sensitive to oxygen and spoil however, there are even more powerful such as the failure of capacitor, which are unless sealed very carefully. Some OLED LED blubs for directional or flood lighting. often electrolytic and prone to drying out panels are coming to market, but the price Solving the heat management problem has when exposed to heat for long periods, will likely make them technology show- been an important objective for assuring a the entire lighting assembly is rendered pieces rather than candidates for everyday long life for the LED, but heat also impacts useless; that is, unless the lamp assembly lighting. In contrast, LED-generated light the life of the transformer electronics used owner is a savvy electronic handyman who has proven efficient, durable and capable to convert standard home AC current into can repair the transformer. Unfortunately of being produced in great quantities. As the lower voltage DC current required for this is a task that is normally beyond the they are a rapidly emerging type of light- LED operation. One developer has shown skills of the vast majority of lighting con- ing, they are still expensive compared to 100-watt-equivalent LED lamp prototypes sumers. Even skilled technicians can be incandescent or CLF. A typical LED bulb designed to manage the problem of cooling challenged to disassemble and repair the can contain from a just a few to a dozen or the LEDs by using microscopic devices that electrical transformer circuit, especially if more light-emitting diodes, which are tiny move air over the chips, like miniature fans, they are encased in an encapsulant, as is semiconductor chips in packages, costing a solution which is clever but also expen- often the situation. In either case, the cost up to $1.00 each. sive. However, LED prices are coming of the repairs will often exceed the cost of While LEDs do not produce as much down quickly, and the US Department of purchasing a new lighting element. heat as incandescent bulbs, they still pro- Energy expects a 60-watt equivalent LED duce substantial local heat density and the bulb to cost $10 by 2015, putting them Parsing the problem heat they do create shortens the lifespan within striking range of the price of a Given the current situation, it seems rea- and reduces the efficiency of the chips. compact fluorescent bulb. Indeed, a recent sonable to assume that significant benefit Moreover, placing a dozen chips tightly visit to a local major home building supply could be gained by creating a simple light- spaced together to conform to bulb-shaped chain store by the author, revealed LED ing repair solution which can be effected package that will fit in today’s legacy lamps on sale for $7.00. by the average consumer in a fool-proof lamps and sockets makes the heat prob- Given this preamble, it is highly evident manner and one which would obviate the lem worse, and the brighter the bulb, the that electrical lighting solutions, where the need to discard an entire LED lighting 52 – Global LED/OLED Supplement — Autumn 2013 www.globalledoled.com Lighting with LEDs: The elephant in the room problem assembly when only the electronic portion ture would be advantageous; still, these vated by some other means including but of the bulb assembly normally fails (i.e., the solutions may prove less than optimal and not limited to: motion, vibration, sound, transformer circuitry).
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