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Archive for January, 2011

Intematix Delivers Remote-phosphor Optics Family

26 Jan

Luminaire makers can rely on blue LED lights sources and use Intematix’s phosphor-coated optics to offer products such as downlights in color temperatures ranging from 2700 – 4000K.

Intematix has long supplied phosphors to LED manufacturers that allow blue LEDs to produce white light, and is now supplying phosphor-coated optics for remote-phosphor solid-state lighting (SSL) designs that utilize blue LED sources. At launch, the ChromaLit family includes 45- and 61.5-mm diameter, phosphor-coated plastic optics that offer conversion efficacies ranging from 170 – 196 lm/W.

Intematix director of product marketing Julian Carey claims that the remote phosphor approach delivers a 30% gain in system efficacy compared to designs that utilize white LEDs and a secondary optic such as a diffuser. The ChromaLit optic both includes the phosphor and diffuser function in one element. According to Carey a diffuser can account for a 9% light loss in luminaires.

Blue LEDs and a mixing chamber

Since taking over as Intematix CEO in August 2010, Mark Swoboda has pledged to focus on a materials-centric business leveraging its phosphor technology, believing that phosphors dictate the quality of light. Swoboda said, “Phosphor is the arbiter for light quality. It has a direct effect on the color of light, the color rendering, and the color consistency.”

Intematix’s Carey states that the ChromaLit approach will prove much simpler for luminaire makers. Carey claims that the remote phosphor will eliminate the need for manufacturers to bin LEDs. Intematix recommends that designs use blue LEDs with a dominant wavelength of 457.5 nm, but won’t require binning of the LEDs to ensure color consistency.

Luminaires based on ChromaLit only require the blue source, a mixing camber, and the ChromaLit optic. Carey said, “The ChromaLit source is intrinsically diffusing” and he asserts that the design reduces glare.

Carey also pointed out that luminaire manufacturers can take advantage of the remote-phosphor efficacy in several ways. The efficacy will give manufacturers the option of offering brighter products, or to cut cost by using fewer LEDs. Designs can also reduce drive current for lower power consumption and a simpler thermal design according to Carey.

Remote optic dictates color temperature

Initially the ChromaLit family includes 2700k, 3000K, 3500K, and 4000K optics in both 61.5- and 45-mm sizes. Those sizes immediately enable the design of downlights, spot lights, and modular light engines. Indeed the larger size is a match for popular 6-inch downlights. The first products rely on phosphor printed on a plastic substrate, although Intematix has plans to offer glass substrates as well.

The company also plans to develop more complex shapes relative to the initial flat and round optics. Carey said, “We will make domes and spheres and even custom shapes for customers.”

Intematix also believes that the remote-phosphor technology will prove useful in other applications such as automotive signaling applications. Carey stated that the company can use the technology to yield red and yellow lights.

Intematix has already begun sampling the ChromaLit components. They expect customers to launch ChromaLit-based products in the coming weeks.

Swoboda concludes, “We will be a disruptive alternative for making general lighting systems. Manufacturers can now start with a blue light source and combine that with a ChromaLit component.” And Swoboda believes that approach will yield higher-quality and lower-cost SSL compared to designs based on white LEDs.

 

LEDs Light Inside and Outside of Asian Games Venue

20 Jan

LEDs take center stage literally at the Asian Games as Seoul Semiconductor products provide stage lighting and Osram provides external venue architectural lighting.

Seoul Semiconductor Z-Power LEDs lit the stage at the 2010 Asian Games opening ceremony in Guangzhou, China. Osram LEDs provide decorative and architectural lighting on the outside of the new Haixinsha Square venue that hosted the opening ceremonies and will host other events including the games’ closing ceremonies.

Seoul Semiconductor lights Asian Games stage

Golden Sea Professional Equipment, a Seoul Semiconductor partner, provided the Z-Power-based LED solid-state-lighting (SSL) system that illuminated on-stage performances at the Asian Games opening ceremony. Brian Wilcox, VP of North American Sales for Seoul Semiconductor, said, “Featuring rich color, the Z-power Series provides exceptionally consistent lighting for a more pleasant viewing experience, and improves visual detail.”

Golden Sea chose the Z-Power series based on the light quality afforded by the LEDs that generate white uniform light that achieves an 80 rating on the color rendering index (CRI) scale. Golden Sea also noted that the LEDs create outstanding evening visibility for a comfortable and safe environment.

Energy efficiency and long life are recognized advantages of SSL in general illumination applications, and those same advantages played a role in the SSL deployment at the Asian Games. The Z-Power series delivers 100 lm/W at 350 MA drive current, and the LED stage lights can last 100,000 hours – as much as 130 times longer than conventional lighting, according to Seoul Semiconductor. The LED lights also contain no toxic substances and fit this year’s Asian Games theme of “high-tech, energy saving, going green.”

“As a leading supplier of high-quality lighting in mainland China, we strive to bring the most advanced, most value-added lighting solutions to our customers,” said Zhang Wei Kai, president of Golden Sea. “The Asian Games is one of the largest events in China this year, and I am sure our partnership with Seoul Semiconductor was instrumental in enabling us to secure this monumental win. Their LED lighting products are best-in-class, featuring excellent technology, energy efficiency, and are completely safe for the environment. It is always a pleasure working with them, and we looking forward to tightening our relationship in the future.”

Lighting Haixinsha Square venue

While Golden Sea LEDs light the stage inside the venue, Osram Oslon SSL LEDs provide the multi-colored architectural lighting on the outside of the new Haixinsha Square stadium. The project includes around 200,000 LEDs integrated in 3200 floodlights.

Osram LEDs provide architectural lighting

The architectural lighting utilizes a mixture of Oslon SSL amber/green/blue LEDs in some flood lights along with warm white LEDs in others. The lights yield different combinations of colors to highlight the structure of the outside of the stadium.

Guangzhou Joinmax Display Technology Limited installed the lighting system. General Manager Jiansheng Chen said, “We have experimented with a few designs and have finally opted for bidirectional asymmetric lens design and DMX online system which can make the whole lighting system more easy to use and to create dynamic lighting effects.”

“We are very excited that our Oslon SSL LEDs are part of the Asian Games opening ceremony,” said Kai-chong Cheng, Marketing Director of Osram Opto Semiconductors Asia Ltd. “Millions of visitors at the venue and viewers through television broadcasts will see how well these amber, blue, green and warm white LEDs deliver a colorful profile of the stadium.”

The Asian Games began on November 12 – the day of the opening ceremony. The games will run through November 27th with more than 11,000 athletes from 45 nations competing.

 

Flexible LED Arrays Target Biomedical Applications

08 Jan

University of Illinois research yields flexible arrays of LEDs that could be used as medical implants, but that might find other more near-term practical applications.

Both the trade and popular press have hyped the story coming out of the University of Illinois about flexible LED arrays that might be implanted in the body in various medical applications. The more interesting aspect, however, may be the manufacturing technique and how it might be applied to other applications. Indeed, the technique can deposit arrays on a variety of flexible materials ranging from aluminum foil to rubber to paper, and can support waterproof deployment.

The media has focused on the medical application because that is a potentially exciting idea and the research led by John Rogers was focused on that area. Scientific American has among the best accounts of the stretchable LED sheets developed by Rogers and his colleagues detailing applications such as photoactivated drug delivery.

The medical application, however, could be five or even ten years down the road. Moreover, it’s likely that implantable technologies remain the last choice in terms of how to solve a medical problem due to the cost of developing the technology and the potential risk involved.

The manufacturing technique developed by Rogers and his team, however, is quite ingenious and potentially useful in other applications. Indeed the researchers even wrapped a string of the LEDs around a thread.

LEDs are typically manufactured on a substrate such as a rigid semiconductor wafer. The University of Illinois team follows that typical path to create an array of LEDs on a wafer. The team then dissolves the top layer of the substrate freeing a planar stretchable LED array that can be transferred to other flexible substrates. For instance, the array can be encased in plastic or rubber for implantation in the body – or perhaps for underwater uses.

The manufacturing technique yields LEDs that measure 100 microns (micro meters) wide and only 2.4 microns thick. The conductive strands that connect LEDs in an array can be stretched or twisted.

Until now, organic LED (OLED) technology has been the primary option for applications requiring planar light sources with flexible properties. The new LED technology may or may not compete with OLEDs, but the latter still faces manufacturing issues that have gated volume production.

 

Bayer Develops Thinner Polycarbonate for LED Lenses

08 Jan

Makrolon FR7067 polycarbonate plastic achieves UL flame retardant requirements in 1.5-mm-thick LED lenses that offer near 90% light transmission.

Bayer MaterialScience has developed a new polycarbonate plastic for LED lenses – especially for solid-state-lighting (SSL) applications – that can meet the UL-94 V0 ratings for flame-retardant characteristic at half the thickness of most polycarbonate lenses. Lenses made with the 1.5-mm-thick Makrolon FR7067 material can improve light transmission efficiency to almost 90%.

“Thicker lenses or covers translate into an unnecessarily heavier and bulkier part. This additional thickness is also undesirable because more light will be lost as it is transmitted through the lens or cover, making the component less efficient,” said Gerry DiBattista, market segment leader, IT, Electrical/Electronics Polycarbonates, Bayer MaterialScience LLC. “When it comes to LED lenses and covers, thinner is better.”

DiBattista’s first point is that OEMs and injection-molding specialists enjoy a significant cost advantage when a lens uses less material. The fact that you get better light transmission adds to that advantage.

The LED lens doesn’t necessarily have to meet flammability standards, but there is a payoff for a lens that does. DiBattista said, “Another added benefit is that when a lens meets the required UL flame ratings, the OEM can avoid costly power-supply isolation or a separate UL test on the final component.”

Bayer is also quick to point out that its lenses add to the environmentally-friendly characteristics of LED lighting. The polycarbonate material is amenable to recycling, reprocessing, and reuse. That characteristic fits well with the fact that LEDs reduce energy usage in lighting applications and don’t contain hazardous materials such as mercury.

“Bayer MaterialScience’s latest flame retardant polycarbonate plastic provides OEMs a transparent, UV-stabilized material that not only meets key industry guidelines and regulations but does so with a thinner profile and environmental benefits, too,” DiBattista said.

Last year, Bayer introduced Makrolon FR7087 polycarbonate, which meets UL-94 5VA rating at 3.0 mm with good transparency.

“This builds on several other new products geared toward this industry, underscoring our commitment to support advances in the LED lighting industry,” concluded DiBattista.

 

LED Lens – Helping to Increase the Illuminating Efficiency of the LED

08 Jan

A lens is an excellent accessory for improving the optical efficiency of light-emitting diodes (LEDs). The criterion for determining an LED lens depends on the application for which the LED is used; i.e., the (target) illuminating body. The characteristics (for example, beam) of the LED will also play a significant role. Lenses are generally manufactured from optically clear materials such as polycarbonate or glass, although colored materials are occasionally used to obtain particular results.  Lenses require curvature on one or both sides in order to achieve the proper effect.

How Lenses Work:

The curved surface of a lens refracts light — it bends light rays and forces them to focus at a different point.  (A full technical explanation of this phenomenon is beyond the scope of this article.)  There are two types of lenses, convex and concave, and each is used to produce a different result.  A convex lens will force light to converge and focus nearer to the lens; a concave lens will force light rays to diverge, or focus farther away from the lens.  This is the same principle as that of the human eye, which contains a lens that focuses light on the retina.

Lenses for Use with LEDs:

When a lens is used in association with an LED, it’s referred to as a secondary optic.  In general, LEDs emit light on a directional basis, and the angle of the beam falls between 15-120 degrees.  This focused use of light allows for greater efficiency when compared to traditional light sources that diffuse light over an entire area, as a lower amount of power can provide a similar amount of light.  However, to use LEDs in a light fixture, this 15-120 degree beam must be concentrated by use of secondary optics such as lenses or reflectors.

Improving Light Efficiency:

The lens position is crucial for optimum light efficiency.  If the lens is too high or low from the LED, then it will not focus light at the correct place.  Ensuring that the lens axis is properly aligned with respect to the LED is also vital to achieve the correct output.  Both measurements must be precisely determined and followed, or the lens will produce light that is fractured or too diffuse. A typical value for acceptable accuracy is within ±0.2 mm.

Panel Lenses:

Lenses can be mounted on panels for a variety of uses.  A traditional method is to mount the LED so it can stick out through a hole in the panel.  Other approaches to installing LEDS include such options as using glue to attach them to panels.  However, this method has a number of drawbacks:  the angle of the LED will be reduced; it is susceptible to issues relating to push-through; and electro-static discharges can pass through the LED and negatively affect components on the circuit board.

 
 
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