This week: Brighter LEDs through a GaN-on-GaN process, comparing the light quality & longevity of retrofit LED products, and happy turkeys under LED lights.
Comparing retrofit LED products
SPIE published the results of a two-year study by Danish researchers, carried out in 2010 and 2011, which found that a number of consumer-grade SSL sources have lower quality and luminous efficacy than anticipated. Some even failed to measure up to the incandescents and halogens they were intended to replace. The researchers applied the standards of the EU LED Quality Charter, which is a voluntary program to increase residential lighting efficiency.
We found that the majority of products tested had a CRI above 80 in accordance with... the EU-QC... On the other hand, with regard to efficacy, there is a large spread in the values for similar light quality... overall, we found that only 48 of the 194 directional light sources and six out of 72 non-directional lamps satisfy EU-QC requirements.
The group retested 48 of the LED replacement products at intervals of 1000 hours of operation. Extrapolating the luminous flux data, the researchers concluded that some of the products tested would not reach an L70 lifetime of 50,000 hours. They saw a wide variance in depreciation, noting that "some lamps [would have] a useful life of less than 10,000 hours, which is in the range of standard compact fluorescent lamps." The researchers are maintaining a comparison site (in Danish) to inform consumers about the results they obtained.
Marvell's semiconductor wins
Going into Lightfair this week, Marvell released a couple of pieces of good news. First, the company joined Daintree's ControlScope Connected partner program, in an attempt to move its ZigBee-on-a-chip solution more deeply into the commercial / industrial space. Marvell's 88MZ100 SoC (system-on-a-chip) was announced at the beginning of last year, incorporating four functions that had usually been delivered on separate chips: a ZigBee transceiver, an ARM processor, flash memory, and a DC-to-DC converter. At Lightfair, in conjunction with Daintree and Marvell, driver manufacturer Orama will be showing off a new integrated wireless ZigBee LED driver using the Marvell SoC.
Marvell's other news is a partnership with Samsung ahead of the latter's entry into the residential bulb-replacement market. Samsung will be incorporating Marvell's 88EM8183 LED driver IC into its consumer products. Marvell's claim to fame with this driver is compatibility with more than 150 different models of wall-box dimmers.
Soraa's bright idea: GaN-on-GaN
It's not news that the company co-founded by Shuji Nakamura is betting on its GaN-on-GaN process to enable brighter LEDs, able to operate at higher temperatures and currents, and eventually to lower costs. Soraa also claims "perfect spectrum" light at a CRI of 95. The company is introducing a second generation of its lamps that are 40 percent brighter than the original, 50-W-equivalent product. I'll write more here about the Soraa Vivid MR16 after I have seen it at Lightfair. And watch this space for a deeper look at GaN-on-GaN, coming soon.
Farmers in Minnesota are upgrading the lighting in their turkey barns with LEDs, under a state-funded study that's trying to document the performance of LED lighting in this demanding environment. (Most turkey barns are hot and dusty.) "Farmers are primarily interested in LEDs because of the energy savings, but some also dislike compact fluorescents and have concerns about mercury contamination if CFLs break inside barns," according to Midwest Energy News. But some farmers are taking advantage of the controllability of LED lighting to implement programs such as scheduled dimming and brightening at dawn and dusk. The theory is that turkeys living in conditions more like natural light will fight less, reproduce more, and grow faster. The jury's still out.
— Keith Dawson , Editor-in-Chief, All LED Lighting