Electronic Design
LEDs Will Light The Solid-State Future

LEDs Will Light The Solid-State Future

Few, if any, would argue that solid-state lighting (SSL) implies anything other than the use of LEDs as a light source. Solid state is synonymous with semiconductors, so the correlation prevails.

For at least 15 years, we’ve been hearing how LEDs will soon replace almost all other technologies involved in general illumination. Whether in homes and businesses, decorative lighting, street lighting, signs, automotive, or pretty much any other application requiring light, these highly efficient devices will provide the same or more light while consuming less energy and generating less heat than incandescent and halogen bulbs. They will outlive their predecessors, including compact fluorescent (CFL) components, by significant margins while being more environmentally friendly when recycling time comes.

Despite the promises of longer and more efficient performance, LED-based components are still fairly expensive compared to traditional alternatives. For example, a 60-W incandescent bulb costs about $2 retail while a 60-W equivalent LED-based replacement costs approximately $15 to $20. The extra expense could be justified by the 10-year lifespan of the LED alternative as well as the savings in power consumption, though consumers on a short-term budget might not appreciate the long-range picture.

Costs and other considerations aside, LEDs are infiltrating more markets as well as gaining a greater foothold in established ones. With worldwide initiatives to phase out incandescent lighting permanently, there is some evidence that LEDs will be the golden child of future lighting applications.

LEDs VERSUS WHAT?

Let’s assume LEDs become the technology of choice for present and future lighting applications. Are there any alternative or competitive technologies in the loop now or coming down the pike in the near future? 

“Organic LED (OLEDs) are making some noise, but currently are limited to display panels and backlights. It could be some time before OLEDs can reach the necessary brightness levels to be an efficient, long-life general-lighting option like 1-W, 2-W, and 5-W LEDs,” says Jordon Papnier, marketing manager at LEDtronics.

“Certainly, OLEDs will find a place in the market eventually. However, we do not feel they will have broad appeal for many years,” says Mike Picini, vice president of solid-state lighting at Molex. “Remember that the penetration of LEDs in lighting is still very small, less than 5% of all lighting applications. We would expect, as in other semiconductor developments, there will be advances in the process for the current emitters and new packaging technologies that will make LEDs more cost-competitive in the future.”

“There are a number of materials being developed by the bulb industry to compete with higher LED efficacy. As the LED continues to improve, it will be interesting to see if alternate materials will be able to keep pace,” says Mike King, visible LED assembly manager at Optek Technology.

“LEDs will dominate the lighting market during the next decade,” says Hans-Otto Schlothauer, global product market leader for LED lighting at Sabic Innovative Plastics “During the first several years, CFLs will run in parallel to LED lighting. The next technology will be the OLED. However, this technology still needs a few years to be fully developed and commercially available.”

“Philips Lumileds expects that LEDs will be the primary light source and within the next 10 to 20 years will clearly be the dominant lighting technology,” says Steve Landau, director of marketing communications at Philips Lumileds Lighting Co. “We do not see any other technologies at present that can or will deliver the quality, efficacy, reliability, or cost effectiveness of LEDs.”

So if we sum and average the market consensus, the LED revolution is here to stay uncontested for quite some time.

ROOM TO GROW

Although LEDs are versatile enough to fit just about any lighting application from typical to esoteric, what sector of the market will provide the greatest potential for growth and innovation?

“General illumination is the single greatest opportunity for SSL. The breadth and depth of lighting applications is virtually infinite. General illumination is wide, and applications are typically categorized by market segment,” says Heather Goldsmith, global marketing and communications manager for Future Lighting Solutions.

“The greatest areas for economic growth within the solid-state lighting markets are within the general illumination market,” agrees Brett Shriver, director of sales at Global Lighting Technologies. “Whereas most homes have one or more TVs, there are multiple lights present in each room, which would be replaceable by LED devices.” 

“The LED has become the most common light engine for televisions and displays,” says King of Optek. “LEDs improve contrast ratio and reduce power consumption. For handhelds, the higher LED efficacy allows power consumption to be reduced and the operating time between battery charges to be increased.”

“Talking about general lighting with LEDs, we see strong growth in the field of consumer and professional retrofits as well as in LED luminaries and the respective light engines,” says Bernhard Stapp, vice president of solid-state lighting at Osram. “The driver to switch to LEDs are favorite payback periods. LEDs will certainly be on a par with other powerful and low-consumption types of lamps, for example, halogen or CFL-HID products. But we don’t believe that there will just be LEDs.”

“The main drivers for LEDs in the consumer market are less energy consumption, longer lifetime, increased design freedom, and legislation,” says Schlothauer of Sabic. “The retrofit design, coming from the need to replace incandescent light bulbs and low-voltage spotlights due to incandescent-lamp termination, will be the first big opportunity for the LED lighting market. LEDs will not only dominate the consumer lighting market, you’ll find them in many other types of lighting applications, in particular TV backlighting. Another is the down-light market, where we see opportunities for more and newer LED solutions.” 

DESIGN CHALLENGES

The tech market is more than a little fickle. Sometimes, highly complex products like smart phones and PCs find their way to market almost as quickly as they enter the obsolescence pool, while highly functional products with longer life spans are slow in emerging. Such is the case with a lot of LED products, particularly those earmarked as replacements for traditional lighting. What are some of the roadblocks designers are facing in this market?

“Some challenges are management of heat and power consumption as well as matching color consistency in large applications,” says Tony Carrella, president of Traxon Technologies.

“Engineering an SSL solution is significantly different than a conventional solution. In many respects it’s like designing a consumer product, incorporating PCBs (printed-cicuit boards), semiconductors, components, software controls, thermal management, and more,” says Landau of Philips. “This is a true paradigm shift and in some cases requires new learning and skills.  However, the engineering disciplines required are not new and there are well understood methods for managing heat, designing optics, and packaging.”

“It comes down to a packaging problem: how to best package the LED component, other components to drive it, cool it, and provide an overall efficient lighting system,” says Picini of Molex. “As with the rest of the data, telecom, and consumer electronic markets, it’s about being innovative with materials, processes, and subsystem solutions to provide value in the overall lighting system and fixture/luminaire.”

“As LED chips deliver more watts and put out more light, they also get hotter, and heat kills the LED chip,” says Papanier of LEDtronics. “To get the full light energy out of these chips, better heat management material is necessary to dissipate the heat away from the LED chip. Currently it takes too much raw material like aluminum alloy housing or magnesium alloy to make a simple light bulb.”

COOL SOTA SSLs

In terms of innovation, there’s no shortage of current, unique state-of-the-art (SOTA) SSL products, addressing everything from street and home lighting to stage and video applications.

Introduced as the first four-channel LED cyclorama/wall-wash luminaire, the Altman Spectra CYC 100 LED lamp (Fig. 1) relies on light engines developed with the assistance of Future Lighting Solutions. The component employs an unusual combination of Luxeon Rebel red, green, blue, and amber LEDs. It also can produce deeper tones and warmer colors via the addition of amber LEDs.

An A19-style incandescent replacement, the DEC-A19-5X1W DécorLED series (Fig. 2) from LEDtronics consumes less than 7 W while delivering 40-W equivalent brightness. Units come with softly diffused, precision domed lensing that directs light at a 95° beam. They’re available in warm white at 3000K and pure white at 6000K.

Promising maximum efficiency and sustainability for street lighting applications, Osram’s Streetlight Advanced LED module (Fig. 3) uses significantly less energy than conventional lamps. It houses an LED, lens, and reflector. An additional lamp socket resides in the luminaire housing. If more efficient LEDs become available, users can snap new modules onto the existing socket without tools. The module boasts a color-rendering index of 75 to 80, a lifespan up to 50,000 hours, and a color temperature of 6000 or a warm white at 3000K.

Delivering 16.7 million colors, the Traxon Technologies String and Dot XL LEDs (Fig. 4) can replay effects, lighting patterns, video, and live streams. They also offer lower maintenance and electricity costs, less heat emission without UV radiation, durability, and long life. With dynamic control via DMX/DVI capabilities, both are available in cold white and warm white options.

Divided into five string elements, each element of the String consists of 32 individually controllable, high-brightness LEDs mounted on a flexible, semi-transparent cable with 5.25 lumens per node, resulting in a total of 160 pixels per String set. The Dot XL is available with three, six, or nine LEDs with 16, 42, and 63 lumens per dot casing, mounted on a pliable cable with customizable pixel pitch options.

Also, Traxon Technologies says that its Mesh RGB (Fig. 5) is the first truly all-purpose component that allows the installation of LED screens in any space. Available in three different versions, each Mesh module comprises eight interfacing grid units, linked with vertical fixed dot strings. This gives it the flexibility to contour to the most unusual surfaces. Each grid unit measures 31.25 cm by 25 cm by 1.65 m with a pixel pitch of 6.25 cm.

In addition to allowing for screens in any size with less front-to-back space than comparable LED screens, the Mesh RGB addresses the blurring of boundaries between lighting and video. It accepts virtually any lighting or digital video input signal through its data box controlled via DMX, e:pix, or video input. Each module also featrues 160 individually controllable pixels.

ADDRESSING THE SMART GRID

The new messiah of utility brokers, the Smart Grid, is a conundrum of allegedly power-saving and money-saving technologies wrapped into the power-delivery apparatus. What, if anything, are lighting OEMs doing to embrace this emerging topology in terms of compliance and compatibility?

“LED lighting is digital. Adapting and conforming to the intelligent control systems is relatively easy. The SSL advantage is the ability of an LED lighting system to incorporate ‘smart’ controls into its fixtures, i.e., dimming, proximity sensing, power saving, etc.,” says Goldsmith of Future Lighting. “However, we must also be cautious of where intelligence is built in and recognize where it is ‘needed’ versus ‘wanted.’ Looking at the big picture, a fixture has to be commercially viable. Just because the technology exists does not mean it needs to be designed into everything.”

“LED lighting is the most efficient lighting option when it comes to using renewable energy sources like wind, solar, or biofuels,” says Papanier. “Most LED fixtures can be designed to run off the lower-power grid sources like 12-, 24-, or 48-V dc systems. No step-down energy wasting converters or inverters are needed.”

“Solid-state lighting represents a shift from analog to digital, and along with that comes systems and controls. Systems and controls are as much a part of the new lighting paradigm as LEDs are,” says Landau. “There is certainly much to be done in terms of compatibility and standards, and it’s clear that the industry is moving forward along many fronts. It’s reasonable to expect that the market will see the solar, software, and computer/electronics industries making significant moves into the lighting segment.”

THE BOTTOM LINE

One of the major selling points for SSL is that it is more efficient and will save money for consumers and commercial users alike. Okay, imagine that we all go out and replace our incandescents and CF bulbs and start to see some savings in the monthly electric bill. Then, the utility providers will start crying poor and jack up their rates, erasing those savings. Consumers and businesses would incur costs in upgrades, and they essentially would have no recourse for them. What, if anything, can the lighting OEMs do to protect their customers’ objectives and investments in this situation?

“The money savings holds true even as the cost of service from the utilities increases,” says Shriver of Global Lighting. “If you choose not to utilize the higher-efficiency devices, then you will be using more power. So as the cost increases, you will see an increase in your monthly bill. Businesses that have not incurred the costs in upgrades will be paying even more than those that have upgraded to more efficient devices. The delta remains the same.”

“We have seen this happen in California in the past,” says Papanier. “A few years ago when we had statewide rolling blackouts, a push was made to save energy. Residents responded and saved too much energy and the power companies claimed they were losing money and requested and got their rate hike. We need to put in place legislation that protects the consumer against rate hikes because of energy-saving measures. The utilities need to cut costs before requesting rate hikes.”

“This question may not adequately address what some governments will have to do to be sure utilities act in the best interest of their customers and hold rates,” says Picini. “With a more modular LED subsystem approach, this may actually enable new business and finance models for the utility industry. With a module you could imagine, just as with a digital cable TV box, the utility company could lease the LED module, charging for its use, and create new ways to gain revenue through better monitoring of electricity used for lighting.”

“Ultimately, the savings realized through the implementation of solid-state lighting solutions come from many sources. In addition to saving energy, which should result in lower bills, there are also savings realized from maintenance reductions that can be particularly significant in commercial enterprises and may eclipse the savings from energy reduction,” says Landau.

“Additionally, although not direct end-user savings, SSL implementation will reduce the need to build additional power plants, reduce the total energy used to create, distribute, and dispose of lighting equipment (due to longer life), and reduce the usage of mercury in lighting solutions,” Landau adds. “Together, these represent significant social, environmental, and economic benefits.” 

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