LED Industry Interaction Intensifies

If you’ve recently walked through lighting or LED-related, conference exhibit aisles, you may have been momentarily blinded by the seemingly, ever-brighter LEDs found in exhibitors’ booths, because LEDs are becoming brighter and more efficient. Even better, you’re seeing improved color quality. Expect this trend to continue, because much is going on behind the scenes.

I’ve just returned from San Diego, where I attended the Ninth Annual LEDs 2008 and first-ever LEDs Measurement and Standards conferences. This event provided 440 attendees with firsthand insights for LEDs future. A 61-booth tradeshow accompanied the conference. The event was organized by IntertechPira (www.intertechusa.com) and directed by LED Consulting’s Kathyrn Conway, along with representatives from Cree, Osram Opto Semiconductors and Philips Lumileds.

The first day comprised five, introductory seminars that overviewed the solid-state lighting (SSL) industry, driver technology, thermal and optical designs, and luminaire-construction strategies.

The following days’ topics covered emerging LED markets (most notable was backlighting systems for LCD-based TV screens, monitors, and notebook computers); street lighting; residential and decorative lighting; next-generation lighting solutions for signage applications; and the high-brightness, white LEDs for automotive headlights and general illumination — the most demanding technology. Presenters represented large, medium and small LED and lighting manufacturers, driver producers and luminaire testers, as well as such supporting organizations as the U.S. Dept. of Energy (DOE) and the U.S. Environmental Protection Agency (EPA).

LEDs 2008 also included a panel/audience discussion on improvement of LED efficacy, color rendering and quality. We also debated LED lifetime claims.

By agreement, we limited LED standards and photometric-measurement topics because a separate, two-day, measurements and standards conference immediately followed LEDs 2008, in the same venue.

At the exhibit, the DOE spoke of its Energy Star SSL program and reported on the Illuminating Engineering Society’s (IES) adoption of the LM-80-2008 standard, that is, the “Approved Method for Measuring Lumen Depreciation of LED Light Sources.” The DOE also advised LED and lighting manufacturers how to qualify products for its Energy Star criteria. It now provides a preliminary document, “Manufacturer’s Guide for Qualifying Solid-State Lighting Luminaires,” which outlines performance benchmarks. The document lists DOE’s certified facilities that conduct Energy Star qualification testing; it also details Energy Star approval procedures.

Interestingly, the EPA also has an Energy Star program that includes a residential, LED-based, light-fixture qualification.

LED measurement and standards
The first-ever, LEDs Measurement and Standards workshop attendance headcount (94 attendees) surprised the conference producers. Notably, the SSL-standards activities and criteria, driven by ANSI, IEC and IES, and supported by DOE, NIST, UL and others, has been accelerating. This progress, and additional challenges, were discussed by 18 presenters, myself included. Presenters represented popular LED manufacturers Osram, Philips, GE and Cree; and testing organizations NIST, DOE, RPI’s Lighting Research Center, Pacific Northwest National Laboratory (PNNL), Luminaire Testing Laboratory, Instrument Systems, Labsphere, Optronic Laboratories Inc. and Gamma Scientific.

More interesting points
The participants were concerned with complete SSL-systems issues, more so than I have observed elsewhere. The group discussed optical and thermal design, as well as simulation techniques using sophisticated software tools that enable optimal thermal management and desired optical-radiation patterns. The attendees were also interested in relevant photometric measurements, parameters and testing procedures and, as well, debated color-quality definitions, color rendering and color-temperature descriptions.

The SSL community needs to clearly define its measuring of “white light” color parameters for indoor and outdoor environments. Mastering the phosphor technology is crucial behind producing the desired-color white LEDs. Nichia and the University of Applied Sciences (Muenster, Germany) presenters discussed this issue.

One panel topic focused on identifying key technologies that make SSLs more efficient. The goal was to identify methods or qualities that could increase lumen/watt efficacy.

Conversations didn’t yield comprehensive answers to this complex subject. One panelist spoke referenced such exotic materials as “quantum wells” and improved material morphology. These and other systems will, hopefully, lead to even higher lamp efficiency.

Such feedback supports my belief that a similar, more efficient, laser-technology track will also lead to more efficient LEDs. (High-efficiency lasers employ quantum wells and more controlled epitaxial-growth systems, to produce high-quality, material morphology.) I extend this analogy beyond the material level, to device and sub-system levels, meaning, an overall LED-efficiency boost will come from more optimized, optoelectronic-chip design; phosphor technology; improved mechanical, thermal and electrical designs; and housing construction.

The LEDs Measurement and Standards conference held two panel discussions at the end of each day. These allowed lively, presenter/audience dialogue. The hot topics: photometrics for SSL vs. traditional light sources, color-rendering indices, LED-junction temperature and lifetime controversies, and binning issues. Clearly, the audience and presenters were hungry for resolutions, which says further work is needed.

Other challenges
The conference didn’t address SSL product-cost challenges, one of which is poor product yield, which leads to complicated binning practices. Another challenge is non-uniform material and manufacturing process variations, which lead to inconsistent SSL product performance.

Certainly, future cost reductions will evolve from increased production counts, but also from tighter manufacturing controls and controlling variations, which may require more fabrication-tolerant chip designs and processes.

LED safety
I presented on LED safety (theoretical and practical LED efficacy limits and safety concerns) in the LEDs Measurement and Standard conference, where the audience appeared to particularly appreciate learning that, as LEDs become more efficient and can sustain being driven by higher current, they can enter a “superluminescent” operating zone and become excessively bright – possibly causing ocular hazards from direct viewing.

They also valued my discussion on possible biological and environmental hazards coming from arsine and phosphine-related semiconductor compounds which are present in some LEDs (see ST, November 2008, page 58).

Finally, Kathyrn Conway, in her “Illumination Market Trends” presentation, discussed SSL’s most notable advantage: energy savings. She explained energy-savings concepts in terms of lumen/W limitations, and the LEEDs program, which limits total energy consumption per building.

These limitations may not be enough, or always appropriate, because, while using very high-efficacy SSLs for illumination, end users can still waste energy by using too many lamps. Imposing efficacy and size restrictions and, ultimately, limiting “lumen/person” usage may properly address the energy-consumption issue. Conway agreed that the “lumen/person” concept could, or perhaps should, take off.

More on LEDs 2008
In Q3 2000, IntertechPira (Portland, ME and London) launched its first LEDs conference as an extension of the OLEDs World Summit. The initial conference drew 120 delegates and 15 exhibitors. This year, LEDs 2008, in San Diego, drew 439 delegates from 255 affiliations in 16 countries. The 2008 conference also featured 20 sponsors and more than 40 exhibitors.

The conference format comprised an interactive panel discussion, exhibitor forum, network functions and a LED measurements and standards forum.

IntertechPira says the LED industry growth is 10 to 15% annually; it’s projected to grow to $7 billion by 2010.

IntertechPira provides information on sustainability, R&D, globalization, new markets, production methods, and regulatory and compliance issues. It also provides events, training, online information and publications for new technologies.