If you want to quickly assess the health of an industry, one option is to take a brief look at the progression of its conferences. In the case of the euroLED conference series and the sector of the III V industry that it supports, this approach provides an excellent overview of current trends. The inaugural euroLED meeting held in the UK back in the early noughties was a very small affair, but over the years the conference has moved to larger premises, first to the National Motor Museum in Birmingham and more recently to the Ricoh Arena, part of a complex that is also home to Coventry City Football Club.

The migration to larger conference premises is reflected in the attendance figures for euroLED, which was held this year on 8-9 June. Although the size of the audience listening to the talks at euroLED 2011 was comparable to that of a few years ago, many more delegates were mingling in the exhibition hall. In this cavernous arena, companies from all around the world were displaying a vast array of solidstate lighting products, plus ancillaries for driving and testing them. The exhibition included an incredibly strong showing from China, with many, many firms showcasing their portfolios of LED lamps in various guises.

The topic of LEDs for general illumination was also the focus of the opening remarks given by Bob Pollock, Senior Vice President of Worldwide Sales at LED chipmaker Cree. Pollock did not spend time justifying why the LED lighting revolution is a certainty, rather than just a possibility, because he knew that he would have been preaching to the converted. So instead he showed the audience how they can play their part in driving this sea-change in the lighting business, by giving them a crash course in how to make the best possible case for LED lighting.

Pollock did this by showing delegates a great resource for promoting the strengths of LED lighting – a two-and-a-half minute video by General Electric. This video clearly sets out the major benefits of LEDs for general illumination: greater efficiency than incumbent sources, lower maintenance that stems from longer lifetimes, and a product that is better for the environment. According to the film clip, in terms of efficiency, the LED is 68 percent more efficient than a high-pressure sodium lamp for area lighting and 80 percent more efficient than neon lights used in signage lighting. What’s more, its lifetime  of 50,000 hours is more than double that of fluorescent and high-intensity discharge lamps, and it has good green credentials, thanks to the absence of mercury, lead and glass. These attributes translate into significant cash savings - a city with a million people that switches from highpressure sodium streetlights to LEDbased equivalents could save $6 million over the lifetime of the solid-state lamp.

The greater emphasis that the LED industry now places on general illumination was also a central messages in the opening talk, which was given by Jamie Fox, Research Manager for LEDs at the UK based firm IMS Research. “In 2011, general lighting has, for the first time, become the top focus for component manufacturers,” said Fox.

According to him, the reason for this shift in focus is that the LED market for TV backlighting will saturate around 2013, and chipmakers are now looking at how they can grow their sales through the latter part of this decade and beyond. TV backlighting accounted for about half of the LED revenue ramp from $6.1 billion in 2009 to $10.2 billion in 2010, and will significantly contribute to the more modest global revenue growth in 2011. However, by 2016, LEDs for general illumination will be a major part of the LED business, due to a growth in revenue from around $1 billion today to $6 billion in 2016.

Fox also discussed the massive ramp in MOCVD reactor shipments to China, which have been spurred by government subsidies of up to $1.8 million per tool. In 2009, global MOCVD tool shipments stood at 227, and IMS expects this to shoot up to 1089 this year. This tremendous growth in worldwide production capacity is expected to lead to oversupply of LED chips and downward pricing pressures on these products, issues that were detailed at length in an interview with Fox’s colleague, Ross Young, in the previous issue of Compound Semiconductor (see “China’s LED chipmaking boom fuels overcapacity” June p.38).

A European perspective

Reflecting the focus of the conference,Fox offered an overview of the EuropeanLED market. Here Philips and Zumtobellead luminaire and fixtures sales, andPhilips, Osram, and General Electricdominate shipments of LED lamps(replacements for incandescents andcompact fluorescents). Of the 105-110million LED lamps shipped in 2010, 27million went to Western Europe. Sales tothis region are tipped to grow at 50 to100 percent per year, according to Foxwho is preparing a more accurateforecast. He believes that high levels ofLED lamp penetration will only occurwhen prices plummet to $10 or less.

Following Fox on the podium was Mark van den Berg, Philips Lumileds’ Director of Marketing for Europe, the Middle-East and Africa. He discussed the quality of LED light, which he believes has overtaken efficacy as the principle focus for chip improvement; and he spoke about what is needed to drive market adoption. In his opinion, the greatest threat that Lumileds faces to expanding its sales does not come from rival chipmakers, such as Cree, Osram and Samsung, but from makers of  compact fluorescents.

van den Berg pointed out that one of the biggest obstacles to greater adoption of LED lighting is the complexity associated with defining the performance of this light source. In his opinion, it is only possible to make a good decision on what product to use after scrutinizing datasheets and understanding the application.

According to van den Berg, an LED light source must excel in five separate areas if it is to give a high quality of white light. For starters, it must have a colour-rendering index (CRI) exceeding 80, and ideally 90, with particular attention paid to the rendering of shades of red. The solid-state lighting source must also be evaluated at its running temperature, and it must deliver colour consistency between the LED and the luminaire. In addition, the LED sources must deliver great colour consistency within the beam, and over the lifetime of the device.

To drive far higher market adoption, van den Berg claimed that LEDs must deliver a higher quality of light at a far lower price. In addition, he said that standards applied to this form of light must approve – “[today] it is quite a mess and not consistent.”

Other factors also come into play, which depend on the target application. For example, for the lighting of outdoor areas, van den Berg said that the payback associated with LED deployment is too long, and must reduce to less than three years through improvement in the cost per lumen and chip efficiency. Warmer colour temperatures that are stable for decades are also needed.

Another sector, office light, is a “tough market” to penetrate, according van den Berg. He pointed out that the T5 fluorescent is a very cheap incumbent with an efficacy comparable to that of the best LEDs of today. To have success here, makers of LED lighting must convince owners of offices to reconsider their approach to lighting this space by looking at lux levels. If they think along these lines, they may switch to greater use of task lighting and to lower ambient lighting, changes that may lead to increased LED deployment.

To enable LEDs to penetrate these areas and also replace conventional bulbs in the lighting of shops, van den Berg believes that the cost per lumen must fall by 95 percent. Delivering this massive hike in affordability will require improvements to recombination, extraction and phosphor conversion efficiencies, plus higher drive current densities, superior package designs, higher chip yields, greater fab utilization and the availability of better production tools.

When Pollock spoke, he echoed many of the points made by van den Berg. But he also ventured into new territory, showing the audience how far the LED community had progressed in recent years: between 2006 and 2011, the efficacy of industry-leading cool-white LED products driven at their maximum drive current increased from 50 lm/W to 90 lm/W, and the cost per lumen fell by more than an order of magnitude. Pollock also detailed the improvement to the quality of Cree’s LR6 downlight over a similar timeframe. Back in 2007, this high-quality white-light source that blends the emission of white LEDs with red-emitting variants employed 42 devices consuming a total of 12 W to deliver 650 lumens. Last year, the same light output was realized with 8 LEDs consuming 10.5 W, and this product was far more affordable – it had fallen from a commercial wholesale price of more than $100 in 2007 to a retail price tag of just $50.

Issues relating to categorizing thequality of light were highlighted in apresentation from Yoshi Ohno from theNational Institute of Standards andTechnology. He began his talk byexplaining that colour  quality was governed by both the chromaticity of the light source and colour rendering, which is a measure of how the colours of an object are reproduced under this illumination. He then gave clear examples of how two sources with the same CRI could make objects appear to have very different colours.

For years and years, makers of LEDs have been trying to increase the efficacy of their LED chips. The theoretical maximum for any lighting source is 683 lm/W, but that is for a green source of a particular wavelength; a low-pressure sodium lamp could hit 520 lm/W, but the colour rendering of this source is poor.

Putting these figures in perspective, Ohno explained that blue LEDs with yellow phosphors are capable of 294 lm/W, and sources that employ colour mixing of red, green and blue devices could just top 400 lm/W. The quality of the colour rendering provided by such schemes depends on the width of the sources. During fifty years of refinement of the fluorescent lamp, broadband sources have been replaced by narrowband equivalents to improve colour rendering, and Ohno expects the same shift to occur in the LED industry.

Although the presentations of Ohno and many of the other speakers showed that there is still much work to do for the LED lighting industry, the general mood is that this technology is certain to lead a lighting revolution. Many exhibitors highlighted the breadth of LED lighting products that are available today, and this industry is set to thrive as it makes improvements to colour quality and efficacy, alongside lower prices.