LightFair part 2 – High-power LED suppliers

April 29, 2005
LED manufacturers continue to target the lighting market and are creating more usable white products.
A number of high-power LED manufacturers were exhibiting at LightFair, including Nichia, Cree, Osram, Lumileds and GELcore. Cotco, which has had some success with its one-watt Dorado product, is planning to introduce a half-watt device in a tiny package which will target the display backlighting market. Seoul Semiconductor, another high-power LED manufacturer, was also displaying its AC-LED technology, as was III-N Technology, a spin-off from Kansas University.
Osram white LEDs Meanwhile, Lamina Ceramics continued to pursue its strategy of developing high-power packages by integrating numerous LED chips onto a thermally conductive substrate, and launched its 4000-series, including an award-winning RGB device with two 1 mm2 chips per color and an output of 120 lm (see Lamina launches latest super-bright light engines).

As the world's largest LED manufacturer, and the first company to commercialize white LEDs, Japan's Nichia has a strong portfolio of white LEDs targeting the lighting market. Nichia's Dan Doxsee explained to LEDs Magazine that the 0.6 W version of the company's Rigel device is available at a range of key color temperatures.

VS Optoelectronic

Cool white LEDs are manufactured by combining blue LED chips with yellow-emitting YAG phosphors, while warmer white colors (lower color temperatures) can be realized by increasing the proportion of a second phosphor emitting in the red region. While the efficacy of warm white devices is often much lower than cool white, Nichia's devices demonstrate only a gentle gradation in efficacy from 30 lm/W for the cool white temperatures, to 28 lm/W for a color temperature of 4100 K (equivalent to a cool white fluorescent) to 26 lm/W at 3500 K(warm white fluorescent) to 24 lm/W for 2800 K (incandescent).

These efficacy values will each be increased by 10 lm/W by the fourth quarter of 2005, says Doxsee, and at around the same time a 1.2-W version of the Rigel (Power Rigel) will be introduced, featuring a package with better thermal performance. The 0.6 W version of Rigel is supplied in a ceramic surface-mount package which is reflow-solderable and lead free.

While the warm-white version of Rigel provides a typical luminous flux of 12 - 14 lm (depending on the color rank), the higher-power one-watt Jupiter package provides 32 lm for warm white (0.450, 0.408) and 42 lm for cool white (0.31, 0.32). Jupiter is available in the Jigsaw package (LED on metal core PCB), which has a similar footprint to the standard Luxeon package from Lumileds.

White LEDs from GELcore offer range of CCT and CRI
One of the most interesting announcements of the show was a new high-power white LED from GELcore (see press release). The company, a joint venture between GE Lighting and Emcore, has concentrated on the signage market of late with its Tetra products (including a high-power white version). The new lighting product was shown in a dome-shaped package in 1- and 4-watt versions. Kraig Kasler, Vice President of Marketing at GELcore told LEDs Magazine that the 1-watt package contains one chip (1 x 1 mm) and the 4-watt contains 3 chips. The product is scalable to 8-W by adding more chips into the package. “Since the GELcore approach is a remote phosphor system (similar to CFL), it enables various lamp forms,” said Kasler.

GELcore The key difference between GELcore’s approach and others in the market is that the company uses near-UV LED chips emitting at around 405 nm, in combination with phosphor blends that emit at selected wavelengths across the visible spectrum. At this wavelength, the emission from the chip itself contributes very little to the overall spectrum of white light emission, meaning that variations from chip to chip have much less effect on the lamp color point.

Also, GELcore has developed numerous phosphor blends, allowing it to offer expanded color temperature options (3000K, 3500K, 4100K, 5000K or 6500K) and a wide range of color-rendering indices (70 up to 95 CRI) to meet specific end-user requirements (see New GELcore phosphors improve color-rendering index). GELcore indicated that its product has a lifetime of 20,000 hours and an efficiency of 25 lm/W for warm white.

GELcore Representative performance figures include a 1-W package at 4100K and a CRI of 80, with an output of 30 lumens, and a 4-W device at 3500K and 90 CRI with an output of 90 lumens. The products will be available in the second half of 2005.

GELcore indicates that it is targeting settings where quality of light is important - in terms of high color-rendering, low lamp-to-lamp variability and precise color temperature choice – which might include display-case lighting in retail and museum settings, wall-washing in environments such as aircraft interiors, or task lighting in medical applications.

Cree Lighting
As well as announcing a design win for its RGB XLamp LEDs with Color Kinetics (see news item), Cree Lighting was one of two companies (the other being Color Kinetics) to light their booth entirely with LEDs. Cree used more than 3500 high brightness XLamp 7090 LEDs in a series of white and colored fixtures. The luminaires generated nearly 190 kilo-lumens of light with a power consumption of approximately 6,500 watts of power, around half the value required by equivalent incandescent light. "We set out to demonstrate the general illumination capabilities of high brightness LEDs by creating dramatic exhibit lighting," said Chris James, Cree Lighting marketing manager.

Cree Lighting booth Although Cree is one of the premier LED chip suppliers, it has only being supplying its packaged XLamp LED range for about 18 months, and is less well know than some of its rivals. To counteract this, Cree Lighting used LightFair to launch its "XLamp LED Challenge" program to encourage LED specifiers, design engineers and volume purchasers to try the company’s high brightness LEDs in new and existing applications. Qualified LED professionals can sign up for the program on Cree's website and will receive XLamp sample components for testing in their applications.

Achieving a consistent color temperature with LEDs is a major challenge because of the wide color variations inherent in the LED manufacturing process. Manufacturers offer a wide range of products, known as bins, but obtaining color consistency even within a bin can be difficult. For the manufacturers, costs are kept high if they are not able to sell all of their production distribution.

A solution offered by Lumileds was to introduce color-matched white Luxeon Lamps, each containing multiple white Luxeon LEDs, which are selected by advanced binning algorithms. By correctly combining an appropriate mix of LEDs, the Lamps themselves have a well-controlled and consistent color temperatures of either 3200K (warm white), 4100K (commercial white) or 5500K (cool white).

"The lighting community looks for white-point consistency whether viewing the light source directly or the effect that's being created," said Keith Scott. "Our Luxeon Lamps offer the first practical solution to the problem by supplying pre-matched, pre-mounted LEDs that not only provide the desired color consistency but also speed time to market for the finished product."

Also at LightFair, Lumileds announced that its standard Luxeon 1 emitter offers a luminous flux of 45 lm, and the company also showcased its forthcoming redesigned product, designated K2 (see Lumileds upgrades Luxeon I, reveals white lamps).