LED Lighting Grabs Attention

Recently, numerous acquaintances have contacted me regarding LED lighting articles they’ve read in the New York Times and the Wall Street Journal. After having read of this new technology, these friends became excited and, knowing I had firsthand knowledge, telephoned to discuss LED uses and concepts.

After having received the first few calls, I knew something, a sea change perhaps, was looming. My friends had sensed — no, signaled  — an LED upsurge. 

I had similar feelings after visiting this year’s Lightfair tradeshow in NYC. It’s among the world’s largest, annual, architectural and commercial lighting tradeshows, and, in May, it celebrated its 20th anniversary with recordbreaking attendance: more than 23,000 people and 475 exhibitors. From the Lightfair Institute’s opening-day, innovation-award ceremony (where LED-based luminaires garnered the most awards) to the 170,000-sq.-ft. exhibit floor, LED lights, for the first time, overwhelmingly dominated the show.

At Lightfair, David DiLaura, an authoritative and renowned lighting designer, shared valuable insights in his “20 Years of Light and Lighting” address. He said a divergent group of scientists  — ones with no prior lighting affiliations — brought LEDs to market. At that time, DiLaura said, this group lacked lighting knowledge, but, he added, this will soon change.

He also said lighting professionals must accept LEDs because the technology has shown notable lighting capabilities. So much so that General Electric recently announced its discontinuance of its previously touted, high-efficiency, incandescent (HEI) lamps, because it now believes LEDs will be the future lighting choice.

This is extraordinary news —  but what does it mean? Also, when will common-use LEDs be available to consumers — and will they buy?

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Incandescent and CFL comparisons

LED lamps have numerous commercial applications, but the recent attraction, particularly to white-light LEDs, has intensified because of LEDs’ improvements concerning everyday lighting. Essentially, LEDs now promise higher efficiency and longer lifespans in our homes and businesses. The visionaries say LEDs will blow out the Edison-type, screw-base lightbulbs, as they did the gas lamps, more than a century ago. This same squad says LEDs will also take out the now-popular and energy-efficient compact-fluorescent lights (CFLs).

However, this vision can’t take hold until LEDs match the basic traits of incandescent: omnidirectional light and consistent, warm-white color.

Challenges and prospects

LED lighting engineers recognize their product’s color-temperature and color-rendering challenges and under-par color performance, when compared directly to incandescent lights. One might also say Edison- based LEDs are required for extensive household distribution, but, although this fixture type would make retrofits possible, the pundits claim consumers must first judge performance and cost.

We have experienced this with CFLs. Even with the Edison base and the dimmable features that some CFLs now have, these lamps wouldn’t have become popular without the essential warm, white color and light-distribution features. They evolved in common sizes, with twists to provide omnidirectional light distribution. CFL manufacturers also say they’re continuing to improve the white-color quality and consistency.

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In some respects, LEDs are superior to both CFLs and incandescent because of their higher luminous efficacy, longer lifespan, ability to produce single and white color, more robust packaging and the flexibility to produce light sources in various shapes and sizes. Although these higher-performance traits are suited to niche applications, they’re secondary to the warm, white color and omnidirectional radiation that general lighting requires. Another advantage: In many aspects, LEDs have substantial room for improvement as the technology matures.

Although it’s become a popular misunderstanding, LEDs aren’t inherently directional. With revolutionary or clever chip and luminaire designs, they can produce omnidirectional light, and they cast light in any desired direction.

Today’s LED lamps produce narrow-cone, directional light because LED chips are typically manufactured in wafers. However, with added, external optics, the output can disseminate across a wider, conic path. The current directionality feature is suited for accent, down, task and street-light applications.

Cost and availability

Ultimately, LED visionaries’ claims and predictions are hostage to cost, which relates to distinctive, low-yield manufacturing processes. Regrettably, the solution isn’t to produce more LEDs (high-volume production), because the yield percentage remains minute, especially for high-brightness and warm-white LEDs. Therefore, because a high percentage of an LED factory’s output is unusable, end-use buyers pay more for the product.

What’s behind the low yield and high cost? After all, we’ve seen the prices of personal computers, cellphones and other electronic devices drop dramatically over time, so why do LEDs lag behind? One challenge is, the optical properties are more drastically affected by the material and fabrication variations, or imperfections, than the electrical properties. Optical or photon “collision paths” are effectively much smaller than the electron “collision paths”; hence, photons are more prone to scattering from physical media imperfections, which is further degraded because of light absorption properties.

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The same warm glow

At Lightfair, Osram Sylvania’s engineers displayed three, candle-flame-shaped LED lights; the center one was an incandescent light and the side ones were LEDs. This LED B10 lamp display gave the sparkling appearance of a classic chandelier fixture and established that LEDs can produce the same warm glow of incandescent lamps. However, the available LED lamps in the market tell otherwise. For now, at least.

For firsthand research, I visited WalMart and Home Depot stores in the greater New York metropolitan area, to investigate available LED products and their costs. I found only MR-16 and PAR-20/30 types LED lamps, for accent-light applications (using their directional nature). The prices were three to five times higher than corresponding halogen lights, but this may be justified, because buyers, over time, can save money via lower electrical wattage and longer lamp life.

The halogen counterparts had warmer color, near 2,700K — the LED lamps rated near 3,300K.

The unavailability of a general-purpose LED lamp and the high price of directional LED lamps at popular retail home stores show that the LED technology must develop further.

Sign-industry benefits

Recently, the New York Times reported that Taiwan Semiconductor Mfg. Co. (TSMC), the world’s largest foundry chip maker, announced its interest in producing LED lights. While TSMC could drive down LED lamp prices, as it did for computer chips, its entry could also create dreadful competition for the existing LED makers. Rick Tsai, TSMC’s former CEO who now leads a new, business exploration unit, says the company will decide by December 2009.

TSMC has a huge manufacturing capability and $7 billion in cash. It’s well positioned to enter the LED market. If it builds a profitable LED business, expect a dramatic price reduction in LED-lighting products. The price cut will come from manufacturing cost efficiency as well as much improved material and fabrication techniques. These added manufacturing processes should affect LED prices; thus, sign manufacturers will buy high-quality, white- and single-color LED lamps at competitive prices, which will further stir the fluorescent and neon lighting-migration to LED light sources.<

As president of LED Lighting Technologies, Dr. M. Nisa Khan educates the lighting industry and consumers about LED lighting. She has a bachelor’s degree in physics and mathematics, and master’s and Ph.D. degrees in electrical engineering. Email her at nisa.khan@iem-asset.com