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Japan’s Eco-point Program transforms market for LED lamps (MAGAZINE)

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This article was published in the July/August 2011 issue of LEDs Magazine.

View the Table of Contents and download the PDF file of the complete July/August 2011 issue.

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The superior performance of a new technology is no guarantee of market success. Potential adopters can gain experience with innovative technologies by trying them out first, but after new products pass this initial hurdle they often face an even more nagging barrier – higher cost.

In its recent survey of municipal-lighting asset managers across Canada, for example, the Toronto Atmospheric Fund found that 66% of the respondents were using LED lighting in some way and were well aware of its benefits. However, 86% of the respondents said that the high cost of LED technology is the leading barrier to adoption.

Governments employ a variety of policies to reduce the cost of new technologies to speed their market adoption. Feed-in tariffs jump-started the European market for wind and solar generation technologies. China’s Green Light Program, which began in 1996, provided robust subsidies to accelerate adoption of CFL lamps across the country. Chinese companies now dominate this manufacturing sector globally. Meanwhile, the US DOE’s SSL Manufacturing Roadmap has added a new pathway to the agency’s strategy to accelerate SSL adoption, namely R&D funding that will reduce manufacturing costs while enhancing product quality.

Out of Japan comes another approach that has stimulated rapid market uptake of LED lighting – the Eco-point Program. In April 2009, then Prime Minister Taro Aso of Japan announced a large economic-stimulus package that included the $10.9 billion Eco-point Program to stimulate consumer purchases of energy-efficient air conditioners, refrigerators, and televisions. In addition to stimulating the economy, the program sought to reduce greenhouse-gas emissions and hasten digital broadcasting across Japan.

Here is how the program worked. After purchasing an energy-efficient appliance or TV, a consumer received from the government eco-points worth 5-10% of the value of the purchase – with each eco-point worth ¥1. The consumer then redeemed these points for a variety of 271 so-called green goods and services listed in a catalog sponsored by the government. These ranged from travel to hamburgers. Eco-points could also be redeemed for gift certificates for family and friends. Indeed, 85% of redemptions were eventually gifts.

LED lamps join Eco-point Program

In December 2009, the government added LED lamps to the list of redeemable products. From April 2010 onward, consumers were allowed to exchange their eco-points for LED lamps at twice their value. For example, only 2,000 eco-points (instead of 4,000 previously) were needed to redeem an LED lamp priced at ¥4,000 (around $50).

FIG. 1. Replacing all the incandescent and fluorescent lamps in Japan with LED alternatives could have a significant impact on energy consumption, but would have an upfront cost of ¥15.7 trillion, says the Institute of Energy Economics.

The impact of the program on LED lighting products was profound. According to GfK Marketing Services, Inc., by June 2010 consumer sales of LED lamps had surged to 19% of total light-bulb sales by volume, and 60% by total value. Domestic shipments were expected to reach 20 million units in 2010, despite the cost of products ranging from ¥3,500 to ¥3,800 ($43-47). Meanwhile, the average cost of LED lamps fell by about 25%, the result of increasing economies of scale and intense competition among Japanese manufacturers.

In May 2011, the government reported that a total of 450,000 consumer applications had been processed to redeem eco-points for LED lamps (batteries were also included in this category) worth a total of ¥3.8 billion or $46 million.

The double value of eco-points for LED lamps no doubt attracted consumers to these products. Cultural factors also played a role, however. The Japanese love gadgets and are notorious energy savers. Even electric tea kettles boast energy-saving features! So the novelty of LED lamps held strong appeal.

By April 2011, individuals had submitted 44 million eco-point applications to the government, which were worth ¥621 billion ($7.7 billion) in redeemable eco-points. Despite the popularity of the program, critics maintain it did not save much energy. It’s true that 82% of consumer purchases were for energy-hogging flat-screen TVs. Energy-efficient air conditioners and refrigerators accounted for only 19% of the eligible purchases.

The large proportion of large-screen TV purchases was not a surprise. The government plans to end analog broadcasting by July 2011, and the eco-point program was designed in part to ease consumers into the new system.

The Ministry of Economy, Trade and Industry had been expected to revive the program in the Tohoku and Kanto districts that were hit hardest by the March 2011 tsunami, in order to reduce electricity demand and avoid rolling blackouts in the Tokyo Electric Power Co. service area. But the government finally decided not to reinstate eco-points after determining it would not save enough energy.

Energy-saving potential of LEDs

However, with 7% of its electricity generation now out of commission due to the failure of the Fukushima Dai-ichi nuclear power plant, Japan needs electricity conservation more than ever. A recent report issued by Japan’s Institute of Energy Economics (IEEJ) highlighted the opportunities afforded by LED lighting (see Fig. 1 and Report estimates energy-saving potential of LED lamps in Japan).

Lighting accounts for 16% of Japan’s electricity consumption. According to the IEEJ, if all lighting in Japan were switched to LEDs, Japan’s electricity consumption could be reduced by 9%. The residential sector presents a prime opportunity, where incandescent lamps account for 29% of the lighting load.

The government of Japan is now reportedly drafting comprehensive energy-saving measures to address the electricity crisis caused by failing nuclear plants. By design, eco-points targeted flat-screen TV purchases that eventually increased household electricity use. However, the LED component of the program demonstrated that significant energy savings and rapid market transformation for home-grown technologies could be achieved by significantly lowering the initial cost of products in a way that appealed to the public’s values.

In sum, in a remarkably short period, Japan’s Eco-point Program quickly built market share for LED lamps, while stimulating the economy and boosting Japan’s LED manufacturing sector. Despite its cultural biases, the Eco-point Program could serve as a model for other national governments seeking to rapidly transform their domestic retail markets for LED lighting.
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Thick-film technology with aluminum substrates optimizes LED assembly (MAGAZINE)

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This article was published in the July/August 2011 issue of LEDs Magazine.

View the Table of Contents and download the PDF file of the complete July/August 2011 issue.

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As the LED market grows, companies that assemble LED-based products are looking for methods to make them more efficient and reliable, thus making them more cost-effective for the consumer. To guarantee high-quality performance from an LED, efficient heat dissipation is crucial. LEDs convert only 20-30% of their electric power into visible light; the rest converts into heat that must be conducted from the LED to the atmosphere. This excess heat reduces the LED’s efficiency and reliability, resulting in a shorter lifespan. Thermal management, therefore, is essential for maximum performance.

FIG. 1.

In the standard method of LED assembly, the LED component is soldered to a metal-core printed circuit board (MC-PCB), a thermally-enhanced PCB or a ceramic substrate, which is then bonded to a heat sink. While such a configuration is currently popular in the industry, it does not manage heat conduction well and is expensive to produce. Consequently, many manufacturers are interested in mounting LED components directly on aluminum substrates. Although aluminum offers excellent thermal conductivity and is less expensive than ceramic or metal, it requires an insulation layer on the substrate.

Thick-film substrates

For one LED assembler, Norbitech AS, finding an insulation system for aluminum substrates was important in meeting their customers’ requirements. Norbitech, headquartered in Roros, Norway, is a supplier of electronic manufacturing services to the international market. The company executes SMT and high-level assembly, and is well-known in the industry for its thick-film production techniques.

“We use thick-film technology to manufacture hybrid circuits with inorganic substrate materials,” says Roar Sundt, Sales and Project Manager for Norbitech. “Typically, the circuit-manufacturing procedure entails the deposition of several successive layers (resistive, conductive or dielectric) onto an electrically-insulating substrate using a screen-printing process.”

FIG. 2.

Although the most common substrate material is ceramic plate, thick-film pastes can be printed on special steel alloy plate or aluminum alloy plate. Thick-film pastes offer a highly reliable solution for many purposes such as automotive, high-frequency applications, and high-power/high-voltage electronics.

Fig. 2. shows the stages in a typical thick-film process. Thick-film substrates can be assembled with all types of SMT electronic components by using soldering, gluing or wire-bonding processes. With these methods, thick-film technology has several benefits, which are also shown in Fig. 2.

Manufacturing challenges

Working with high-power LEDs and ceramic substrates can present challenges, says Sundt. “In 2005, we started working with high-power LEDs using standard thick-film material,” he says. “At that time, this was a good solution since thermal conductivity was acceptable (28 W/mK) with ceramic plates (alumina) compared to similar PCBs. However, the mechanical strength of ceramic substrates is fragile, making the ceramics prone to cracking. Mounting to the heatsink was becoming a challenge for our customers.”

Norbitech needed to find a solution to the mechanical problems, and they found their answer in Heraeus Materials Technology’s Insulated Aluminum Materials System (IAMS). Heraeus, a supplier of products for thermal-management applications, developed IAMS as a low-temperature firing (less than 600°C), thick-film insulating system that can be printed and fired on aluminum substrates. The IAMS material set consists of dielectric pastes, conductors, solder masks, and resistors.

According to Mitsuru Kondo, Global LED Project Manager for Heraeus’ Thick Film Division, IAMS was designed to be compatible with aluminum processing conditions. “The IAMS technology allows the LED circuit design to be screen-printed directly onto the aluminum substrate,” explains Kondo. “Because the IAMS pastes can be fired at less than 600°C, the problems of cracking and bowing are eliminated.”

Solving the problem

Heraeus’ paste system permitted Norbitech to print directly onto aluminum, allowing them to take advantage of all the benefits aluminum has to offer. “Aluminum is a less-expensive base material than ceramics,” notes Sundt. “Since a lot of today’s high-power LEDs are electrically insulated at the heat slug, IAMS allowed us to print directly between the LED and the aluminum. The heat transfer from the die to the substrate is excellent.”

Another advantage to using IAMS pastes is minimal material waste, resulting in lower production costs compared to etched MCPCBs and thermally-enhanced PCBs, where sheets of copper are chemically etched to create the circuit.

“IAMS is an additive process with selective deposition capability,” says Kondo. “The conductor paste is deposited only where the circuit is located. Thermal vias connect easily to the aluminum substrate.”

Norbitech used several of the IAMS products including IP6075 Lead-Free Dielectric Paste, an insulating paste that produces an extremely dense, grey, hermetic-fired film; C8829B Low-Temperature Silver Conductor, a low-firing, lead- and cadmium-free, silver-conductor paste; and PD5200 White Epoxy Insulator, a screen-printable, single-component, fast-curing, modified-epoxy coating for circuit protection.

Successful cooperation

In past experiences, Norbitech was not able to find a standard paste system that would exactly fit the application needs of its customers. By working closely with its customers and Heraeus, Norbitech was able to fine-tune the quality and the functionality of its customers’ products to fit the application.

“IAMS minimizes thermal resistance by reducing the number of interfaces or layers required in an LED module,” explains Kondo. “It allows low-cost design changes, offers the ability to use less expensive substrates, increases conductivity, and lengthens the LED’s life span.”

All IAMS pastes also meet RoHS requirements, which are especially important to Norbitech, since all the products they produce must meet these standards. Norbitech has held ISO 14001 environmental certification since 2004, and Heraeus has been in the forefront of developing RoHS paste systems.

To ensure that IAMS can provide the thermal management properties that are so crucial to LED manufacturers, the system has undergone extensive independent testing.

“The test results concluded that LEDs soldered with IAMS paste operated at cooler temperatures than the LEDs that were soldered on MC-PCBs,” notes Kondo. “The measured thermal resistance between the LED active junction and the board’s bottom was up to 10-percent lower with IAMS than in the MC-PCBs.”
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Building blocks of intelligent lighting design help create successful LED products (MAGAZINE)

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This article was published in the July/August 2011 issue of LEDs Magazine.

View the Table of Contents and download the PDF file of the complete July/August 2011 issue.

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The long-awaited hockey-stick expansion of the LED-based lighting marketplace is beginning to take shape as more replacement fixtures are entering the consumer and industrial landscape. The market potential is leading more product-development teams to attempt their own solid-state-lighting (SSL) designs, whether the product is a small MR16 or a larger PAR lamp. Yet herein lies the issue. LEDs are powerful semiconductor devices, and so allow product developers to deliver a whole new world of differentiation with their designs, such as intelligent lights with sensors and dimming capabilities. Lamp and luminaire designers are no longer defining LED fixtures only in terms of basic lux and color requirements.

In this still-maturing technology segment, many product designers are still coming up to speed on the language necessary to understand how to build any of this potential intelligence into their lighting system. This puts them at a disadvantage when it comes to discussions with potential vendors and partners. The developers, trying to grasp a changing and maturing technology landscape, need an understanding of the basics – the building blocks of intelligent lighting design.

These essential questions can help a developer understand not only how to correctly define a project, but also how to choose appropriate partners, design-service providers and vendors.

Building Block #1:
Do you require dimming?

The dimming question is tougher than it appears at face value. A “yes” answer sets off a daisy chain of follow-up questions including three major issues: input voltage, the dimming scheme, and dimming quality/performance.

Let’s first consider the input voltage. Low-voltage fixtures such as MR16 lamps that have inputs of 12 VAC or 24 VAC make it more difficult to develop a driver that can operate with the majority of the TRIAC dimmers installed in the existing infrastructure. Companies such as Cypress and Zetex are creating such drivers at this time. For standard line-voltage applications, there are many more available drivers that support TRIAC dimming. At the high end, there are a small number of 277V dimmers that are available for high-bay lighting, although the requirement for this feature is trending upward.

The second issue is the type of dimming-control required (see page 49 for more information on dimming-control scenarios). TRIACs were not designed to interface with LED systems but are broadly installed. Your new favorite dimmable AC/DC LED driver may only work with half the TRIAC dimmers installed in typical application scenarios. A driver also may be unable to correctly read the low and high end of the TRIAC and so will only offer about a 20-40% dimming range without introducing flicker, especially on the low-voltage side of the range.

If the dimming control comes from a microcontroller, the power from the AC line needs to be appropriately managed. Standard AC/DC drivers from companies such as Advanced Transformer are not made to power a microcontroller that has a 5V input rail. The microcontroller will also require an input signal to control the modification of the output dimming waveform, which can even introduce the complexity of supporting a communication network to carry the dimming information.

The final issue is the quality of the dimming waveform itself, because all dimming circuits are not equal. Dimming is nominally done via a pulse-width modulation (PWM) signal, a digital waveform used to control power (usually current) to the load based on the PWM duty cycle (from 0-100%). But the PWM signal can introduce complications via EMI noise that can result in LED flicker and create obstacles in the regulatory approval process.

The details of PWM signal control are beyond our scope here, but product designers should look for low-noise implementations. Some drivers use pseudo-random control of the PWM signal to greatly reduce noise.

Dimming performance can also suffer in terms of how smoothly a light dims if the control comes from a digital output. An 8-bit PWM waveform only has 256 possible steps that can dim a string of white LEDs. Especially at the low-end of the dimming range, those individual step changes become visible to the user. However, a 16-bit PWM has over 65,000 steps, allowing for a much smoother dimming curve.

Building Block #2:
Do you require feedback?

The notion of actually being able to adjust the operation of a light engine on the fly, based on input from sensors and operating characteristics such as temperature, is an advantage that LEDs afford. Yet the concept is new both to product developers working on lighting and to lighting designers.

In the case of LED lighting, sensing and control can yield more robust products from a lifetime standpoint. In part this is due to proactively preventing potentially-damaging operating conditions. Any LED system should be able to appropriately track different conditions such as overvoltage, undervoltage, short circuit, open circuit, and thermal runaway. Let’s consider how monitoring these conditions can be leveraged using Fig. 1. While this is an example using a Cypress Semiconductor driver, other IC vendors support similar sensing in simple white-light applications.

FIG. 1.

The circuit relies on a transformer (in dotted lines) to create an isolated topology, which makes it easier to pass UL certification. However, the circuit itself is able to sense what is happening at the load through the tertiary winding of the transformer (at the bottom of the transformer), and as such is able to recreate the waveform internally and adjust how it drives the LEDs.

The circuit also includes a temperature sensor and will shut down if the temperature rises above a set threshold. Temperature is the bane of the existence of LED lighting design engineers, since LEDs conduct all their heat through the base. This puts the engineers into an uncomfortable position of having to work as much on thermal design as on electrical design. This ensures that temperatures do not rise beyond datasheet junction temperatures of the components on the PCB board and cause a failure. Also, it’s widely known that temperature dramatically affects the flux and color output of the LEDs themselves, which can make the visual appearance of a row of fixtures appear to be different in color or brightness.

A system with added intelligence and driven by a microcontroller can implement an improved temperature-compensation algorithm using a simple and cheap thermistor placed near the LEDs themselves. After reading the board temperature, a well-known equation is used to calculate the junction temperature of the LEDs. Junction temperature is equal to the temperature measured on the board plus the product of the thermal resistance of the board, the constant current of the LEDs, and the forward voltage of the LEDs. These are all easily-discoverable values. The calculated temperature can then be used to derive any adjustments to the drive current or voltage in order to keep the flux output (or the color output of an RGB series of LEDs) inside the visible limit.

Building Block #3:
How do you want to drive the LEDs?

This is another simple question that becomes more complex the moment you bring a power engineer to the table. When faced with the omnipresent cost question, most engineers will quickly turn to a linear implementation, which can cost half of the switching alternative. Unfortunately, the tradeoff for using a linear drive system is about a 50% hit in the overall system efficiency, and that tends to counteract the green energy-efficiency advantage of LED lighting.

Switching implementations typically use either a step-down buck or step-up boost topology. There is a wide range of suitable driver ICs on the market that support such topologies. But product developers should keep a critical eye on a few operational features that can crucially impact performance.

The first is switching frequency. For example, if a driver is able to switch at 1.5 MHz rather than 1.0 MHz it will reduce the size of the inductor needed for the circuit, which in turn helps solve the inevitable board-space crunch in most retrofit applications.

A second key specification is a resistance value called RDSon, which is associated with the high-voltage MOSFET that switches the output and in some cases is integrated in the driver IC. If that RDSon value is too high, over 1 ohm for example, then the power dissipation will suffer, again killing the efficiency of the system.
The final key concern is the driver efficiency specification. A decent switching regulator can get up to 95% efficiency, which can differentiate a lighting system effectively in this competitive marketplace.

Building Block #4:
What’s going to set your product apart from the competition?

To be frank, this final question is about the sum of the parts of a lighting-system design that truly differentiate a product – or the lack of differentiating features. There is a veritable crush of companies seeking to carve out a space in this burgeoning LED retrofit market. Many will simply decide to create a non-dimmable or TRIAC-dimmable LED fixture or lamp and try to win in the market based on low cost. These companies will rise and fall based on the commodity pricing of basic components, not on the quality of their overall system.

Companies who instead desire to push forward with a combination of simple differentiating techniques will carve out unique and stand-alone spaces for themselves. Many lighting engineers simply don’t know enough of what’s available in the semiconductor market to take advantage of simple solutions. These techniques include some features in LED retrofit bulbs and fixtures, and other features in complete lighting system designs. Fig. 2 depicts some examples.

FIG. 2.

The block diagram shows a potential retrofit bulb. It takes the AC/DC line voltage such as 120 VAC, and then drops the voltage to drive a microcontroller which handles the TRIAC dimming of the LEDs. This is a similar approach to creating the PWM signal that we discussed earlier. However, this example also interfaces with a motion sensor that is a relatively low-cost external device that might be implemented in a lighting system. The sensor detects the presence of an individual in a room, causing the intelligent light to turn on automatically. A sensor that can be in the sub-$0.10 range can result in a product that is easily differentiated from the competition.

Consider as a second example a table lamp. In the simplest fashion it takes an offline signal and drives a set of white LEDs with no dimming. Again, there are multiple vendors in the market designing this lamp. However, the development team can differentiate the product with the addition of a capacitive touch-sensitive slider on the lamp to both turn the light on and off and to adjust the dimming level. Adding a capacitive slider to a design that already includes a microcontroller can cost as little as a line of copper on a circuit board. In other words, it is not expensive but yet again provides a unique advantage.

As a final example, consider outdoor backlights, such as those used behind restaurant signs. To save energy, the restaurant will want to drive the sign at different levels in the day or at night. But the simplest version of an SSL design will not allow such control.

There are driver ICs that allow software control of the constant current used to drive the LEDs. For example, the level might be software-adjustable from 350 mA to 700 mA – significantly changing the brightness. Such an LED backlight design can offer even more energy savings to the potential customer, maximizing efficiency during the entire day.

There are far more examples of features the lighting-product developer will encounter as LED technology continues to mature. Examples include additional communication interfaces, control mechanisms or thermal platforms. Differentiating a product in this market is not an onerous process, does not have to be costly, and can ultimately help a company position itself effectively. The building blocks discussed here are obviously not the only questions necessary to create an intelligent lighting fixture, but they offer an excellent starting point to successful products.

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LED-based poster-box reference design overcomes optical and cost challenges (MAGAZINE)

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This article was published in the July/August 2011 issue of LEDs Magazine.

View the Table of Contents and download the PDF file of the complete July/August 2011 issue.

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The lightbox, widely used for advertising displays and in decorative lighting, is simple, relatively cost-effective and easy to design and manufacture. Traditionally, the focus of poster-box manufacturers’ engineering efforts has been on producing metal frames in various shapes and sizes. The light source was an apparently trivial issue: conventional poster boxes use T5 or T8 fluorescent tubes, which have the advantage of being both inexpensive and technically simple. The main challenge is to produce an evenly-illuminated surface: this is a matter of adjusting the depth of the metal frame to allow sufficient room for light diffusion.

So is there scope for innovation and new technology to add value to the humble poster box? An LED-based reference design developed by Philips Lumileds provides a model for imaginative poster-box manufacturers to follow. This article outlines the key technical issues that manufacturers will need to address in implementing an LED-based poster box. A range of tools are available to guide the optical, electrical and thermal design decisions that manufacturers must make.

Why use LEDs?

By implementing an LED-based design, the poster-box manufacturer can offer customers important environmental, performance and financial benefits. A comparison of fluorescent tubes with advanced power LEDs, such as the Luxeon Rebel range of devices from Philips Lumileds, will show that an LED array uses less power (meaning a reduced carbon footprint) and has a longer operating life than fluorescent tubes producing equivalent luminance.

FIG. 1.

LED-based lighting also performs better in cold conditions, while fluorescent tubes perform poorly in the cold. Overall, LED-based poster boxes promise lower energy costs, lower repair and maintenance costs, and less downtime. This last point is particularly important for advertising applications – a poster box with a failed or flickering fluorescent tube is of no value to an advertiser.

And while end-of-life disposal of fluorescent tubes is problematic, because they contain hazardous materials, the materials in LED systems are much more environmentally benign (although subject to the provisions of various waste directives).

Every manufacturer will of course make their own economic calculation to determine the value of switching to LED technology. However, the combination of more reliable operation, lower maintenance costs and lower energy costs certainly has the potential to outweigh the higher initial bill-of-materials (BoM) cost of an LED system.

Changing the light source

In approaching the design of an LED-based poster box for the first time, the most important step is to understand the important differences between an LED and a fluorescent tube.

First, LEDs emit light from a point, and towards the front, whereas a fluorescent tube emits light along the whole length of the tube and from the full 360° circumference. So while a fluorescent tube wastes some of the light it produces, because it cannot all be reflected to the front of the box, an LED’s light can be efficiently collected and directed where it is needed. In other words, LEDs need to generate fewer lumens to produce the same luminance (in cd/m2) as a T5/T8 tube.

On the other hand, since LEDs are point sources of light, a larger part of the design effort must go towards diffusing the light evenly across the surface than is the case with fluorescent tubes.

There are also mechanical differences between LEDs and tubes: an LED is an electronic component and must be mounted on a printed circuit board (PCB) together with other components such as a driver chip. A fluorescent tube simply needs to be mounted on electrical terminals.

The third issue to consider is that both types of light source generate waste heat: the tube heats the air inside the box, while an LED generates a hot spot at its rear. This heat must be dissipated to avoid damage to the LED, and to optimize performance and operating life. In a poster-box design, the box itself can function as a heatsink and the LEDs can be placed directly on the metal casing.

Philips Lumileds reference design

Creating an LED-based poster box design, then, requires careful handling of trade-offs. The key decision concerns the number of LEDs to use. In general, an LED is more efficient and lasts longer when it is driven at a low current, though it will emit less light than an LED driven at a higher current. In addition, a system with a lower number of dimmer point sources can achieve even diffusion of light in a thinner box than a system with the same luminance provided by fewer, brighter points.

FIG. 2.

At the same time, a system that uses fewer LEDs has a lower BoM cost. So the design must find the optimal balance between cost and performance. The Philips Lumileds reference design illustrates the way to manage these trade-offs.

The basic mechanical design of Philips Lumileds’ demonstration model is a simple metal-frame box with an outline dimension of 230 × 230 × 37 mm. The inner dimensions are 210 × 210 × 30 mm. The PCB carries nine Luxeon Rebel LEDs (part number LXML-PWN1-0100) evenly spaced in a square configuration (see Fig. 1).
This design, however, is completely scalable: the width and length of the poster box can be changed at will. An applications engineer from Future Lighting Solutions can work with the poster-box manufacturer to calculate the number and spacing of LEDs and their drive current for any given box dimensions.

The power circuit drives the LEDs at 350 mA to produce a 700-lm output, and efficacy of 71.3 lm/W. Of course, different driver and LED configurations will produce different efficacy values.

An LED has a much lower profile than a fluorescent tube, so it is possible to make the poster box thinner – there is just a 30-mm gap between the LEDs and the diffuser sheet. Normally it would not be possible to illuminate the diffuser sheet evenly at such a short distance from the light source. The reference design solves this problem by use of a secondary optic (Fraen lens F360L-3-RE-OS) in conjunction with a highly-reflective material (MCPET) in the sides and back of the poster box, together with a diffuser sheet on top (Fig. 2).

The lens emits most light at around a 70-degree angle, so instead of being directed at the diffuser sheet the light bounces inside the box before being reflected back out by the MCPET material. This design has the dual advantages of mixing the light – which makes the poster box tolerant of color-temperature variations between LEDs from different bins – and diffusing it evenly across the entire surface of the box.

The system achieves a high standard of efficiency because LEDs are inherently frugal consumers of power, and because the optical design wastes little of the LEDs’ light output.

Comparing solutions

Making a definitive comparison between this LED design and a fluorescent tube-based poster box is difficult, however, as various aspects of the design can have an impact on total power consumption. Nevertheless, poster-box designers should take account of the following factors in relation to the efficiency of LED systems:

• Systems using fluorescent tubes commonly over-specify the tubes to compensate for the decline in light output from a tube over time. Such over-specification is not required in the case of LEDs, which offer superior lumen maintenance and longer replacement cycles, giving a more stable light output over time.

• The efficiency of tubes at lower temperatures drops significantly, and tubes are also prone to flickering in the cold. LED performance, on the other hand, is not affected by the cold, and this is an advantage in outdoor applications.
• LEDs can be dimmed and controlled. With LEDs, it is possible to adjust the brightness of a poster box in response to changes in the ambient light level, and thus to generate further energy savings.
• Brightness control also enhances contrast while reducing discomfort from glare. This helps reduce light pollution, which is a growing concern in city centers.

Tools facilitate system design

Sophisticated tools are now available that enable manufacturers to develop virtual prototypes and experiment with various parameters in order to produce an optimized design.

At a high level, the SSL Designer tool from Future Lighting Solutions (http://bit.ly/jsPgtc) takes the designer’s goals for the poster box – light output and efficacy – and generates a basic specification, in terms of number and type of LEDs and drive current, to best meet the goals. It also provides a financial analysis and break-even calculation, showing whether it makes financial sense to switch from a traditional system to an LED system.

Having established a basic system specification, the Usable Light Tool (also from Future Lighting Solutions) provides a precise calculation of expected lumen output under real operating conditions (such as ambient temperature, thermal resistance and drive current). This allows the simulation of variations in thermal management, board material, power supply and so on in order to find the best combination.

Finally, technical support staff at Future Lighting Solutions can help poster-box manufacturers to model specific design variations and box dimensions based on the reference design, to estimate the effect of using different numbers of LEDs, different drive currents and different LED spacings.

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Report estimates energy-saving potential of LED lamps in Japan (MAGAZINE)

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This article was published in the July/August 2011 issue of LEDs Magazine.

View the Table of Contents and download the PDF file of the complete July/August 2011 issue.

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The Institute of Energy Economics, Japan (http://eneken.ieej.or.jp/en) recently published a report on the electricity-saving potential of LED lighting and concluded that if all lighting in Japan was switched to LEDs, the total potential savings would amount to 92.2 TWh/year. This figure is equivalent to 9% of
Japan’s current total energy consumption. Fig. 1 (previous page) breaks down the savings by sector, and shows that the greatest potential exists in offices and commercial buildings.

Table 1. Cost and payback periods for replacing different lamp types with LED lamps. (*Includes possible infrastructure and labor costs required to make the changes.)

The report says that the switch would cost ¥15.7 trillion (around $197 billion), due to the current high cost of LED lamps compared with ¥100 for incandescent bulbs and ¥1000-1500 for CFLs. However the cost of replacing all the 340 million incandescent lamps would be ¥800 billion (around $9.9 billion). Such a move would lead to very significant savings of 27.3 TWh/year, as well as by far the shortest payback period.

The report also says that the cost of achieving the electricity savings (see Japan’s Eco-point Program transforms market for LED lamps) would be ¥1.3/kWh for incandescent lamps, based on a 40,000-hour lifetime. The figure is ¥14-17/kWh for replacing other technologies, and ¥9.2/kWh on average. In comparison, the cost of photovoltaic power generation is ¥40-50/kWh.

The report notes that households are highly sensitive to initial cost, so eco-point and other discounting measures are likely to be effective in promoting the spread of LED lamps. Meanwhile, businesses may require energy-conversation tax incentives and other subsidies to reduce the burden of up-front investment.

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The time for intelligent LED-based lighting systems is now (MAGAZINE)

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This article was published in the July/August 2011 issue of LEDs Magazine.

View the Table of Contents and download the PDF file of the complete July/August 2011 issue.

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We have the technology pieces that are required to broadly deploy intelligent LED-based lighting systems. Sure there are issues to be resolved such as the multiple wired or wireless interconnects that we might use to network a lighting system. But workable networks exist, mainstream LED-based luminaires support dimming and control, and intelligence is the key to really delivering the energy-saving potential of solid-state lighting (SSL).

You will find intelligent lighting as a recurring theme throughout this issue of LEDs Magazine, shared by contributed features on pages 25, 49, and 63.

Intelligent SSL technology was also a recurring theme in the Lightfair International (LFI) educational program. The “Incorporating lighting technologies of today with buildings of tomorrow” session yielded insight into intelligent lighting and perhaps afforded a view at the direction some industry leaders will take. Speakers included Osram Sylvania executives Makarand Chipalkatti and Karl Jessen; Mark Bauserman, executive director of engineering at Paramount Pictures; and Nadarajah Narendran, associate professor at the Lighting Research Center (LRC).

The crowd was sparse at the early-Sunday session and Chipalkatti used that fact to make a key point about the energy-saving potential of LEDs. Noting the two empty rows in front, Chipalkatti suggested that an efficient intelligent-lighting system would reduce the CRI of the lights that were directed at those empty rows and hence drop the energy those lights used by 25%, without affecting the attendee experience. It’s not just output level that’s controllable in SSL.

Still, first-level savings should come from supplying light only where it is required. Narendran stressed that efficient light sources alone aren’t sufficient saying, “Light source efficacy does not tell you whether you are going to save energy.” Narendran stressed the need for using sensors, and leveraging daylight to minimize the need for artificial light.

Bauserman provided insight from the user side of the equation. He said that when Paramount upgraded lighting with dimmable fluorescent lamps with a CRI of 85, he found that the lights could be set at lower output levels yet workers perceived an improvement in the lighting. And he believes that workers will save energy given the option. He said, “If you give an occupant the ability to control light in their space, normally they are going to save energy.”

Financial story is paramount

Bauserman is planning a major lighting retrofit across the 64-acre Paramount campus. His focus is both saving money and improving light quality. Discussing the pitch he will make to management, he said, “I have to tell the story financially, or there is no story to tell.” But he also added that the lighting must maximize worker productivity and mitigate any worker health impact.

For new lighting, Bauserman is looking for bidirectional communications so that he can automatically detect failures and monitor operations. Other goals include a lighting system that is easy to install and commission, as well as long life, and low total cost of ownership.

It turns out that reading between the lines there was a reason the four speakers teamed on the session. Osram Sylvania’s Jessen revealed that his company would be working with Paramount on a case study this fall involving 2×2-ft SSL luminaires with wireless connectivity. Moreover the test will use a DC grid and Class 2 cable to carry power, eliminating the need for an electrician to install the luminaires. Jessen did not say whether the installation will use the Emerge Alliance’s DC technology, but Osram is a member.

The speakers were careful not to provide too many details, but Narendran earlier had mentioned research that the LRC had done with a technology called Future Tiles in which the researchers used LED-based tiles in the walls and ceilings of a room. Jessen also mentioned “LEDs integrated into things like building materials” as a next phase in SSL. It appears we will have a compelling case study to cover later this year, although the speakers declined to provide more details at LFI.

Every retrofit or new lighting installation in commercial applications should include intelligence going forward. Not every case needs the type of technology that we may see from the Paramount installation, but sensing and controls should be universal requirements and LED sources deliver the best user experience and maximum energy savings.
About the Author

LFI report, part 3: LED technology, outdoor lighting (MAGAZINE)

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This article was published in the July/August 2011 issue of LEDs Magazine.

View the Table of Contents and download the PDF file of the complete July/August 2011 issue.

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LFI report, part 1: Linear LED lighting, OLED and planar lighting

LFI report, part 2: Retrofit lamps, modular SSL

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Section 5: LED technology

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The LED technology that underlies innovative SSL products was also on full display at LFI. As mentioned previously, Philips won an LFI Innovation award with its Luxeon A family. Perhaps the most notable LED trend is the combination of red or amber LEDs with white LEDs to more-efficiently produce warm-white light. In its TrueWhite-based lighting products, Cree has used sensors to monitor the white and red emitters to detect differences in lumen depreciation and adjust drive current accordingly. The company has now decided that the sensor is not needed, eliminating it in the previously mentioned CR linear fixture. Cree’s VP of research and development Paul Pickard said, “Our longevity data indicates similar depreciation rates in both colors of LEDs used in Cree TrueWhite technology. This allows us to design fixtures that maintain their specs, over their lifetime, with no adjustments.”

SSM-80 LED from Luminus Devices

Luminus Devices has been best known for its self-proclaimed big-chip LEDs, but at LFI moved to a smaller emitting area with the launch of the 1600-lm SSM-80 LED. The new LED offers a tighter beam and will target applications such a spotlights used to illuminate retail merchandise. Luminus’ Chuck DeMilo said customers can more easily design drive circuits for the new LED. The device actually uses four emitters in series yielding a 12V stack that requires 1A in drive current. That’s more in line with LEDs from other vendors whereas the Luminus SST-90 product, for example, requires 3.2V and 3.2A.

Bridgelux ES Star Warm White

Bridgelux continues to ride improvements in its LED technology to offer brighter products in smaller packages, announcing the third generation of the LS, ES, and RS LED-array families at LFI. The benefit according to VP of global marketing Jason Posselt is better efficacy and lower cost. Generally, Posselt said the second-generation products offered 75 lm/W in luminous efficacy at $0.013-$0.015 per lm. The new products take efficacy to 90 lm/W and cost under $0.01 per lm. As to how the gains were made, Posselt said, “It’s a sum of epi, chip design and packaging.” He noted that a close examination of the LEDs would reveal that “we’ve added some extraction features to the silicone-coated phosphor on the arrays.”

Osram Brilliant-Mix technology

Osram Opto Semiconductors launched its own Brilliant-Mix technology at LFI, utilizing white and amber Oslon SSL LEDs to generate warm-white light. Osram is advocating the use of a sensor to monitor the different LEDs, thereby ensuring consistent brightness and color. Brian Terao, director of SSL, believes that customers will relish the choice of optimizing a design for efficacy or cost. He said the Brilliant-Mix will yield better efficacy, although the sensor will make it more expensive. Osram said Brilliant-Mix will deliver 110 lm/W in luminous efficacy – 30% higher than can be achieved using warm-white LEDs with similar CRI and CCT.

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Section 6: Outdoor lighting

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The established players in LED-based outdoor-area lighting were all present at LFI, most of whom utilize relatively-small LEDs mounted on a circuit board in an array, and total-internal-reflection (TIR) optics on each LED to form a beam pattern. It’s generally been considered problematic to control the light from larger LED sources although such sources could offer advantages in outdoor lighting since many such applications require significant light output. LFI witnessed more luminaire makers using larger sources. For example, Eagle Eye Lighting demonstrated lights that use its retrofit module based on larger Bridgelux arrays and reflectors that form the desired beam pattern.

BetaLED LEDway SLM

BetaLED stuck with smaller emitters in the new LEDway SLM and LEDway SLM IP66 products launched at LFI. If a street light can be called elegant in terms of looks, then the SLM is the one. SLM stands for single light module and as the nearby photo shows the fixtures are rather sleek-looking relative to the more typical rectangular or cobrahead lights. BetaLED says that the products can replace 70-250W high-pressure-sodium lights. Certainly the development of the SLM products was enabled by significant industry gains in LED brightness.

GE Evolve series luminaires

GE Lighting is the one established player in street and area lighting that has utilized reflector technology broadly in its outdoor LED product line. The Evolve family typically includes one or more closely-grouped arrays of LEDs mounted within circular or rectangular reflector structures. At LFI, GE announced new Evolve series luminaires for area-light, flood-light, garage-light, post-top, and roadway-light applications. The Contemporary Conical luminaire pictured is designed for post-top use and offers a 60% reduction in energy consumption compared with typical HID lights, according to GE.

Eye Lighting KiaroLED area light

Eye Lighting has boldly entered the market with its KiaroLED area light that is the first product to use a TIR approach with larger LED sources. The product is based on Luminus Devices’ SST-90 LEDs. To eliminate light losses caused by the Etendue effect, the TIR must be quite a lot bigger than the source resulting in a 0.75-in-diameter TIR according to Eye Lighting VP of lighting Rob Freitag. The luminaires use 6 to 9 LEDs in linear or rectangular arrays depending on the prescribed beam pattern, whereas outdoor lights based on smaller emitters often use 20-60 LEDs.About the Author

Uglyworld #1233 – Ugly Towers At Nights (Project BIG – Image 230-365)

Project B.I.G. – Image 230/365

Withs me beings away so muchers since we movered intos the new cookie cave as I likes to callers it, the one thing I has been missering mega muches is the awesomer Ugly Towers, insides which I renters a roomer with somes of my coolers friendlies.

I deciders to shows you a litter of how mega coolers the towers looks at nighters when we fires up the LED lighterings that Baz installeds for us.

At the moments it’s probablies a gooder idea that I is travellerings so much as the amounts of roomers is getting mega limiteds in all three towers, so I has appliereds for plannering permissions to gets Ugly Tower #4 buildered, hopefullies it gets approvered so we can all has plenties more spacers.