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MONDO ARC

Event horizon

Issue 52 Dec / Jan 2009/10


In his annual round-up, Dr Geoff Archenhold looks back at a momentous year of developments in LED technology and suggests that this is the dawn of a new era.

The lighting community finds itself in interesting times lumbered with the challenges of the economic credit crunch on the one hand and the disruptive change that LED technology is forcing upon established lighting manufacturers on the other. Over the last few years I have listened to many statements from all parts of the lighting supply chain stating that LED technology is not yet mature enough to be considered as a mainstream lighting technology. However during 2009 the numbers of LED doubters have dwindled significantly which proves one thing - 2009 was the year that LED technology was adopted as the future lighting technology for the global lighting industry - it was an event horizon!

It is clear that 2009 has been a year of significant change for the lighting industry with many of the major lighting brands producing financial results to send shivers down the spine of most analysts.

However the economic crisis has offered significant opportunities with large numbers of smaller companies focusing specifically on LED technology. These companies have taken advantage of the technology disruption and brought highly innovative solutions to end-users. I believe many of the smaller and more innovative lighting companies will develop the skills and understanding of the new technologies faster than traditional brands and the market will see competition that makes for an exciting time for end-users and the lighting market in general. Competition means both lower prices and higher innovation.

There are several reasons why LED lighting have become more readily accepted:
• Consumers are aware of the climate change issues with significant weather events that were supposed to happen once in a 1000 years happening within decades.
• Energy prices are high and set to go much higher so return on investment is key on customer priorities.
• LED performance has significantly improved in both efficiency and colour quality making them the light source of choice.
• LED fixtures are digital and the integration of controls is straightforward compared to traditional light sources.
• Standards for LEDs are now in place.
• The cost of LED emitters have dropped significantly during 2009 making LED fixtures more affordable.
• There is a greater choice of LED manufacturers and LED component suppliers.

Top LED market features of 2009
During 2009 there have been some major LED milestones reached. However the key elements achieved by the industry was the rapid increase in production, LED efficacy, significant rises in CRI, the emerging role of LED emitter arrays and the point when LED CCT binning became better than that found in traditional lamp production.

Major breakthroughs on LED efficiency of note was that of Citizen, Cree and Philips Lumileds - all of whom announced volume production LED emitters that consistently achieved above 100 lumens per Watt. As stated over the past couple of years, efficiency will be the key driver for LED manufacturers until they meet a level where it becomes secondary.

However, 2009 saw the launch of production LEDs where the level of 132 lumens per watt was achieved for Cool White LEDs by the Cree XP-G. The key to this impressive feature was that the LED was based on a bigger LED die (~1.4mm x 1.4mm) and so there is less thermal issues due to a ~90% increase in surface area. The increased surface area also means that the die can run at currents up to 1A whilst providing 345 lumens from 1 die.

Philips Lumileds also announced the Rebel-ES which was the first product to be specified by efficiency rather than luminous output starting at 100 lumens per watt in both Neutral and Cool white products.

The rise in LED emitter arrays was significant in 2009 with Bridgelux, Citizen, Enfis and Sharp all announcing new products that delivered high lumen outputs, high efficiency, or both, in small LED array packages less than 30sqmm.

Rather less obvious was that many of the top LED manufacturers significantly improved the performance of their LED emitters when used in standard operating conditions compared on the LED datasheets.

Philips Lumileds announced that the Hot/Cold factor of the latest Rebels were up to 0.93 in August where the Hot/Cold factor compares the light output of the LED at 100°C Tj and at 25°C Tj. Such underlying improvement in LED emitter technology has been a clear advantage for the fixture manufacturers who could clearly predict how good their LED fixtures would be in production as they would only lose up to 10% of the LED datasheet performance.

Finally, the adoption of standards such as the IES LM-80 lumen maintenance and ANSI C78.377A for CCT and colour space LED metrics has had a major impact on the light quality and performance of LEDs this year with most of the major LED manufacturers exceeding the requirements set out by the standards.

In terms of the short-term future then I believe 2010 will see the LED industry rapidly dominate the general lighting industry with both indoor and outdoor lighting fixtures reaching 100 lumens per watt total system efficiency. The best LED fixtures today producing in excess of 1000 lumens are around the 60 lumens per watt efficiency level including driver, thermal and optical losses, so 2010 will see an increase in performance of 40%. At these fixture efficacy levels even fluorescent tubes and high intensity discharge lamps will be under pressure from LED replacements.

In many ways 2009 was a historic year for the LED and lighting community and so we shall cover this year’s innovation on a month by month basis.

January
Bridgelux: Launch the first members of the Bridgelux LED Array Product Family of SSL light sources designed specifically for lighting applications (see figure 1). The product line helps reduce the cost of light when integrated by customers into solid-state lamps and luminaires. The Bridgelux LED Array products deliver high performance, compact and cost-effective solid-state lighting solutions to serve the general lighting market. These products combine the higher efficiency, lifetime, and reliability benefits of LEDs with the light output levels of many conventional lighting sources. These compact light sources:
• Deliver the light required for general lighting applications.
• Provide illumination-grade, high-quality white light.
• Enable effective thermal management by leveraging Bridgelux’s proprietary Metal Bond Technology helping to reduce the thermal resistance of their LED arrays with figures down to just 0.5ºC/W (this compares to ~9ºC/W for most LED emitters).
• The LED arrays offer a CRI of 80+.
• Reduce system cost and enable simplified luminaire designs.
Product options are tailored to match light output levels of conventional light sources, delivering between 400 and 2000 lumens under application conditions in cool, neutral and warm white colors. In order to satisfy system design requirements, the LED Arrays are specified to deliver these values hot, or under assumed typical use conditions, eliminating the need of incorporating additional sources to account for thermal degradation.
These high lumen output integrated sources reduce system design complexity, enabling miniaturized cost-effective lamp and luminaire designs. Typical applications include task, accent, spot, track, down light, wide area and security lighting.

Xicato: Launch  the ‘80 series’ spot module range - a functional replacement for traditional lamp technologies, offering all the life and energy-saving advantages of LEDs with no light-technical or aesthetic compromises.
• Enabled by Xicato’s proprietary ‘Corrected Cold Phosphor Technology’, the Xicato Spot Module puts an end to the colour variation issues which have until now been a barrier for the market’s acceptance of LEDs. While industry standard LED binning structures allow for colour points in a 7 step McAdam Ellipse, Xicato XSM modules perform to less than a 2 step McAdam Ellipse that is centred on the Black Body Locus at each CCT for a perfectly natural light appearance. 2700K, 3000K and 4000K modules that have Colour Rendering Indices (CRI) of 80+.
• Extensive accelerated life testing proves that Xicato’s ‘Corrected Cold Phosphor Technology’ has the ability to retain its flux levels and colour point over longer periods. Even under the extreme conditions Xicato’s ongoing WHTOL tests (85°C, 85%RH, 1hr on/off), extrapolated lumen maintenance curves indicate less than 30% degradation at 50khrs with colour maintenance within the initial Xicato colour specification.
• The XSM is available at flux levels up to 1000lm at application temperature, despite the relatively small size (<50mm diameter and <20mm in height). Efficacies that approach or exceed 50lm/W are achieved depending on the drive current.
• All Xicato modules are IP66 rated so are ideal for both indoor or outdoor lighting applications.

February
Philips Lumileds: In February the importance of Energy Star in the LED market rapidly increases in the wake of the release of new guidelines and IES LM-80 in 2008. In response, Philips Lumileds begin publishing data and tools to support ongoing development. First, they publish their on-line Chromaticity and Color Spatial Uniformity Tool so that any luminaire manufacturer can use it to perform the complex calculations and abide by the self-certification requirement in the Guidelines.  Secondly, Philips publish data that shows the expected lumen maintenance performance for LUXEON Rebel far exceeds the benchmarks put in place by Energy Star.

Seoul Semiconductor & Nichia: Seoul Semiconductor and Nichia Corporation announce they have settled all litigations on patent and other issues as well as other legal disputes currently pending between them. The settlement included a cross license agreement covering LED and laser diode technologies, which will permit the companies to access all of each other’s patented technologies.

March
Cree: Launch the Product Characterization Tool (see figure 3), an interactive LED design tool that simplifies the task of translating nominal LED performance to real-world conditions. The online tool allows users to easily characterise any XLamp® LED over a wide range of operating conditions, including drive current, flux bin, price and junction temperature. It also calculates metrics such as lumen output, lumens per watt, lumens per dollar and more.

Sharp: Introduce the the Zenigata series of LED arrays that produce up to 540 lumens with just 6.7 watts of power and 48 LED dies attached to substrate as shown in figure 3b. The LED arrays are available in 5000K and 2800K variants in a package only 18mm by 18mm by 2mm high.
 
April
Philips Lumileds: Release the LUXEON Rebel ES. This is the first power LED that is specified by efficacy, not luminous output. It demonstrates clearly that LUXEON Rebel can deliver 100+ lm/W  and >100 lumens at CCTs suitable for outdoor and other applications. The key aspects to note is that clearly the forward voltage of InGaN LEDs are reducing and light output is increasing, a trend which Philips expect will continue for the foreseeable future.

Seoul Semiconductor: Launch a new high efficiency White LED emitter with an efficacy of 120 lumens per watt. The new LCW100Z1 product (shown in figure 5) comes in three ranges of correlated color temperature’s (CCT); including pure white, warm white and natural white with dimensions of only 3.5mm x 2.8mm x 1.6mm. The LED uses a new metal substrate so that luminous efficiency is improved substantially compared to the typical Top View LED and delivers up to 7.8lm (@0.06W) at the low current of 20mA, or 14.3lm at 40mA with a viewing angle of 120 degrees.

Cree: Unveiled the industry’s first multichip MC-E LED with red, green, blue and white chips—all in a single package. It is also pairing new LED chip innovations with its industry-leading XLamp® XP-E package to deliver the highest performance family of discrete, high-power colour LEDs available.

The XLamp MC-E colour is a unique package design combining white, red, green and blue LED chips in a single component. The first of its kind in the industry, this compact component provides design flexibility for colour-changing LED applications that require high flux from a small lighting source, such as entertainment and architectural lighting.
Notice the red, blue, green, AND white chips in the same package.

Cree’s proprietary phosphor deposition process allows them to place chips of different types, colours, and technologies (InGaN, AlInGaP) in the same package without over-spray or cross-contamination:  the phosphor goes where it is needed and this technical breakthrough allows never-before mixing possibilities of RGBW – all in an extraordinarily compact and low-cost package.

Cree also demonstrated their latest LED emitter addition, the XLamp XP-G LED, which offers 139 lumens from a single LED die and an impressive 132 lumens per watt at just 350mA. Driven at 1A, the XP-G produces 345 lumens and has the highest lumen density of any available lighting-class LED, and it is based on the XLamp XP family package. The XP-G shown in figure 6 is able to offer such excellent performance as it uses a larger die (approx 1.4mm x 1.44mm) than found in more typical power LEDs (approx 1mm x 1mm) enabling the current density and thermal heat to be spread across a slightly larger area.

Despite such issues it is clear that Cree possess the production skills necessary to make such an excellent product and the XP-G shows the way in terms of delivering lighting class LED technology in a single die with high lumens output and high efficacy across a wide current range of 350mA to 1A.

May
Nichia: Announce the new HELIOS 9, a 3.5W LED emitter delivering 350 lumens at 5000K using a small package only 4mm x 4mm x 0.85mm high that contains 9 LED die to provide over 95 lumen per watt efficiency at 350mA. The Helios 9 will also be available at 3500K with a CRI of 85 and delivering 250 lumens with an efficiency of 68 lm/W.

Nichia has always been at the forefront of LED development and is the number one LED manufacturer in the world. Their research has always managed to provide a good compass for where LED technology will be within 2-3 years. Figure 7 demonstrates how quickly Nichia can take research innovation and develop it into mass produced LEDs. With an LED in research that has delivered over 249 lumens per watt it is sure that LED will become the dominant light source for the next 100 years.
Luminus Devices: The PhlatLight® SST-90 White LED series wins a technical innovations award at Lightfair. The SST-90 shown in figure 8 follows a trend to use a larger die to deliver incredible lighting performance. The SST-90 uses a 9mm2 LED die to deliver:
• Extremely high optical output: Over 2,250 lumens from a single chip (white).
• Extremely high efficiency: Over 100 lumens per watt at 350 mA/mm2.
• High thermal conductivity package - junction to case thermal resistance of only 0.64 °C/W.
• Large, monolithic chip with uniform emitting area of 9 mm2.
• Lumen maintenance of greater than 70% after 60,000 hours.
• Variable drive currents: less than 1 A through 9 A to full reliability specifications.

June
Seoul Semiconductor: According to IMS Research, Seoul Semiconductor rise to fourth rank in the global LED market and it is found that Seoul Semiconductor is rapidly gaining ground on the top three LED package companies: Nichia, Osram, and Philips Lumileds.

July
Philips Lumileds: Release the LUXEON Rebel PC Amber to the market and fundamentally changes the performance expectations for traditionally AlInGaP products. By using Lumiramic phosphor technology and an InGaN pump blue chip, the LUXEON Rebel PC Amber can deliver 4-5x the light output with significantly better colour stability over time and with the lifetime performance characteristics of InGaN products. At 350mA the PC Amber part delivers 70 lumens typically and up to 130 lumens at 700mA. It also means that RGBA and similar systems can now use LEDs with the same characteristics which simplifies engineering development.

Philips Lumileds also expands the LUXEON Rebel white portfolio with nine new parts that are specifically targeted at illumination applications in the shops, hospitality, and outdoor lighting segments. For the first time, the parts are characterised by CCT and CRI and ANSI binned.

August
Seoul Semiconductor: Announce the new Acriche A4 (see figure 9) that has a luminous efficiency of 75lm/W, and is therefore capable of replacing warm-white incandescent and compact fluorescent light sources in many consumer and commercial applications. The A4 devices have a colour temperature of 3000K and efficiency of 75 lm/W, while also offering a high CRI of 85.

An advantage of the Acriche A4 series is the possibility to use Acriche products on AC mains power freely between 100V and 230V without additional conversion. Only a simple, inexpensive diode bridge is required. However, the A4 differs from other Acriche products (such as A2 and A3 series) in that it uses 50Vrms per package which means a total voltage of 110V-220V can be achieved by connecting multiple devices in whatever manner is needed.

Philips Lumileds: Continue to work on LUXEON performance in real application environments, which means at temperature.  Advancements by their technology and manufacturing teams have enabled Lumileds to provide dramatically superior hot/cold factors for LUXEON Rebel. This becomes very important as people evaluate and select their LEDs. 
LUXEON Rebel becomes the first UL Recognized DC power LED. The impact is a swifter design and approval process and wider range of drive electronics architecture that can reduce system costs.

September

Cree: The XP-G LED, the industry’s brightest and most energy efficient lighting-class LED, produces up to 367 lumens when driven at 1A, at a typical efficacy of 111 lumens per watt is commercially available. It is announced that Neutral and Warm White versions of the XP-G lamp will be released before Christmas.

Epistar: Announce the development of a LED technology that can reach high CRI and high efficacy simultaneously. They demonstrate a white light LED with CRI of 80, CCT of 3000K with an efficacy equal to 80 lm/W. In 2009 Q4, Epistar expects to demonstrate a new product with CRI better than 80 and efficacy of 100 lm/W at 3000K.

The newly developed product includes one or several high-voltage monolithically integrated DC multiple-chip arrays combined with a bridge structure for AC drive. Several of Epistar’s top performance red LED chips are incorporated into this design to achieve high efficacy. This new LED product will offer a significant leap in Warm White LED performance and enable very efficient incandescent bulb replacements to be manufactured.

Philips Lumileds: Release a new LED, LUXEON® Altilon, specifically designed for the automotive sector. However this may be a prelude to the development of a new range of LED array products for lighting similar to other LED companies such as CREE, Seoul Semiconductor, LEDEngin, Bridgelux to name but a few.

The Altilon, shown in figure 10, is made from 2 or 4 LED die and is capable of delivering more than 850 lumens at 1000mA (or 13.7W) with a colour temperature of 5600K in a body of 16.9mm x 15.9mm.

October

Cree: Launch the XLamp® MX-6 LED, Industry’s First Lighting-Class PLCC LED. The XLamp MX-6 LED (shown in figure 11) provides up to 130 lumens for cool white and 107 lumens for warm white at 350 mA. The XLamp MX-6 LED can also reduce luminaire and lamp manufacturing costs through an increased shelf life with reduced moisture sensitivity, and the smallest warm white bins in the industry, enhancing LED-to-LED color consistency.

Cree shift Lighting-Class LED Expectations to 100+ Lumens with the addition of new 100+ lumen XLamp® XP-C LEDs to the company’s line of XLamp LEDs. This addition shifts Cree’s entire XLamp portfolio of lighting-class LEDs into the 100+ lumen range, at 350 mA.

Cree demonstrate record breaking LED light bulb based on the XP-G with the highest lumen output and efficacy reported in the industry. The bulb produces 969 lumens at an impressive 102 lumens per watt, which is the light output equivalent to a 65-watt incandescent bulb, yet it uses only 9.5 watts.

Philips Lumileds: Become the first LED manufacturer to publish LM-80 test reports in the public domain. For the first time, anyone can see what these reports look like. It also clearly demonstrates that drive current, not ambient temperature, is the more significant factor for LUXEON Rebel lumen maintenance. The same cannot be said for other LED products, some of which claim that their lumen maintenance is affected primarily by ambient temperature.

Figure 12 shows the lumen maintenance curve of the Luxeon Rebel at an ambient temperature of 85C and a junction temperature of 98C showing that at 350mA L70 is 67,000 hours.

November
Enfis: Introduce the Innovate Series of Ultra-Bright White LED Arrays with flexible configurations including built-in intelligence with Warm White and Hi-CRI. The Enfis Innovate Series of LED arrays sets a new standard for Ultra-Bright White Light with system configurations delivering over 2500 lumens of Hi-CRI (>92) Warm White (2800K), Neutral (3600K) and Cool White (6500K) light with rated lifetimes of more than 50,000 hours. All configurations are fully dimmable and include the option to monitor array temperature and precisely control lumen output

The Enfis Innovate Series of LED arrays offer a wide variety of general illumination applications including, interior/exterior architectural, street and perimeter, commercial retail, hospitality and residential recess down lighting, and portable and solar lighting systems.

December

Xicato: The Xicato Spot Module range is extended to include the Artist Series which has a CRI of 97. The colour rendering of saturated colours (ie R9 – R15) is as exact as the more easily achieved pastel colours (R1 – R8) resulting in a colour appraisal capability genuinely on a par with halogen lamps which is unique in the world of LEDs and other traditional lamp technologies like CFLs and CMHs. Figure 13 shows the wavelength spectra of the Artist series.

Cree: Announce EasyWhite LED technology – substantially eliminating the need for chromaticity binning for this new class of component LED. The new EasyWhite technology delivers the same chromaticity performance as standard T8 fluorescent lamp technologies, 75% better than compact fluorescent. Cree also release Neutral and Warm White versions of the XLamp XP-G.
 
Final Observations - What to expect in 2010

Steve Landau, Philips Lumileds suggests the following:

• Power LED products are still not generic and what’s true for one product is not necessarily true for those from other manufacturers. This means that there’s significant due dilligence that must be done by the engineers to understand how each product will perform in an application before making an LED selection. The LED manufacturers must continue to provide more, better information that allows this work to be done as easily and quickly as possible. Without that effort and understanding of the differences, it’s likely that some will make the wrong choice and the impact on their business success and customer perception could be impacted.

• Understanding system reliability will take centre stage. Without truly understanding system reliability, warranty, TCO and payback, assessments cannot be accurately calculated. System reliability does not equal lumen maintenance of the LED. It is actually a calculation that considers the following elements: electrical, connections, LEDs, optical, thermal, and mechanical. Strongly related to this is the notion that LEDs don’t fail. They do, as do all electronic components. In LED solutions, the typical approach is to use an array of LEDs. Understanding the lumen maintenance and catastrophic failure probabilities will become critical. Lastly, a clear understanding of these metrics allows systems to be optimised.

• From a product perspective we expect to see significant expansion of the product offerings available to the illumination markets where light output, CRI, and CCT are more finely defined, binning continues to improve and shrink and colour uniformity and quality get significantly better. 

Conclusions
2009 has been a stunning year for Solid-State Lighting that has witnessed LED technology leapfrog CFL lighting in terms of performance and LED driver technology become even more sophisticated and flexible. LEDs have again increased the performance bar with a record 249 lumens per watt efficiency in the Nichia laboratories and CREE achieving over 132 lumens per watt for production LEDs.

2010 will be a significant growth year for LED lighting manufacturers, despite the economy, and we will see a major proportion of traditional lighting companies begin to adopt LED technologies as consumers decide to move to a greener lighting solution.

Next year will see a whole raft of colour tuneable white light products launched on the market enabling users to command the lighting environment. The use of LED technology will also see the incorporation of intelligent controls within fixture designs without significant cost surplus making the energy efficient gap between traditional light sources and LED based products extend significantly.

Of course, LED emitter technology will continue to be enhanced but this is now a secondary concern as focus shifts to high CRI LED products and lower cost systems.

Have a great festive holiday and a happy New Year. Don’t forget you can email me on geoff@euroled.org if you would like to discuss anything SSL.

Geoff Archenhold is an adviser to the UK Government on LED technology and helps LED companies raise investment from the finance community. He is an investor in an LED driver company and an LED fixture company, a Lighting Energy Consultancy and euroLEDs Events LLP.

The views expressed in this article are entirely those of Geoff Archenhold and not necessarily those of mondo*arc.

 

Figure 1: The high performance Cool, Neutral and Warm White LED array from Bridgelux

  • Figure 2: The Xicato module based on remote phosphor technology

  • Figure 3: Cree's online Product Characterization Tool

  • Figure 3b: The Sharp Zenigata 6.7W LED array

  • Figure 4: The first power LED to be specified by efficacy - the Philips Lumileds Rebel ES

  • Figure 5: The new Seoul Semiconductor 120 lumens per watt white LED

  • Figure 6: The new high brightness XLamp XP-G white LED from Cree

  • Figure 7: Nichia's performance chart

  • Figure 8: The new SST-90 high brightness LED from Luminus Devices Inc.

  • Figure 9: The Acriche A4 - Warm White High CRI, AC LED

  • Figure 10: The 850 lumen 4-chip Luxeon Altilon White LED from Philips

  • Figure 11: The new Cree XLamp MX-6 LED

  • Figure 12: The Luxeon Rebel L70 test curves for 350mA at junction temperature of 98C

  • Figure 13: The Xicato Artist high CRI LED module

  • Figure 14: The new Cree EasyWhite binning
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