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comment Cold-Cathode CFLs from Litetronics
Anyone who has used a laptop computer has probably benefited from cold-cathode fluorescent lighting. Now the same technology that back-lights those computer screens is making its way into decorative and area lighting with the Micro-Brite line of cold-cathode compact fluorescent lamps (CFLs) from Litetronics.
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In conventional CFLs, a hot cathode made of tungsten wire coated with barium carbonate emits electrons, which pass through mercury vapor and generate ultraviolet light. It doesn’t take much energy to release these electrons, according to Steve Johnson, former head of the Lighting Research Group at Lawrence Berkeley National laboratory (LBNL) and currently a guest scientist there, but the lamp takes a minute or two to reach full brightness, and the cathode wears out after about 8,000 to 10,000 hours of use.
With a cold-cathode lamp, by contrast, it takes a much greater voltage drop—and hence more energy—to release the electrons in the unheated cathode. “Their efficiency can’t be as high as a hot cathode,” says Johnson. The advantages to cold-cathode CFLs are a long product life, instant-on, operation in very cold conditions, full dimming capability, and the ability to rapidly flash the lamps on and off. As with all fluorescent lamps, mercury vapor is used to produce the light, so used lamps should be properly disposed of.
Litetronics is capitalizing on these properties in its line of Micro-Brite cold-cathode CFLs. The company offers these lamps in a wide range of sizes, shapes, and colors and in power ratings of two to eight watts. The integral-ballast lamps are available with standard A19 screw-base designs (like incandescent light bulbs), and some three- and four-watt lamps are available with smaller, candelabra-style bases for chandeliers and certain other decorative fixtures. Micro-Brite lamps have tightly wound spirals of very thin, T1 (1⁄8-inch diameter) fluorescent tubes. Their rated lifetimes are 18,000 to 25,000 hours, and they carry two-year guarantees.
The white lamps have color temperatures ranging from 2250K to 4100K, a color rendering index of 82, and efficacies of 38 to 43 lumens per watt (lpw). This is well below that of conventional, hot-cathode CFLs, which typically have efficacies of about 60 lpw. Litetronics also offers red, blue, green, yellow and pink lamps. Micro-Brite lamps are instant-on, operate at temperatures as low as –20°F, and are dimmable down to 5 percent light output.
The long life and operating features of Micro-Brite cold-cathode CFLs make them particularly well-suited for outdoor signage. In this application, they typically replace small, colored incandescent lamps, which are “terribly inefficient,” according to Johnson. In a simple test, GreenSource editors found with the low wattages currently available and the relatively low efficacy, the light levels generally seem too low for practical general illumination.
As for the future, most experts suspect that cold-cathode CFLs will eventually lose out to light-emitting diode (LED) light sources. Johnson believes that LEDs will take over these markets, then organic LEDs (OLEDs) will displace LEDs. “There’s no doubt that it will happen,” he says, though it’s unclear when.
Johnson’s colleague Francis Rubinstein, a staff scientist at LBNL’s Lighting Research Group, shares Johnson’s doubts about the long-term market for cold-cathode CFLs. While he believes Litetronics has found a nice niche market with signage, he doesn’t believe that cold-cathode CFLs can compete effectively in general lighting. He expects that LEDs and OLEDs will eventually capture this market, though it may take a number of years for the costs of LEDs to be competitive. Litetronics sells its Micro-Brite lamps online for $8 to $14 each.
In addition to the Micro-Brite cold-cathode CFLs, Litetronics also produces conventional hot-cathode CFLs, including the recently introduced Neolite line of extremely compact CFLs that achieve efficacies as high as 72 lpw. The 13-watt, 825-lumen lamp, for example, has a maximum overall length of just 3.9 inches compared to about 4.25 inches for a standard incandescent light bulb. Each Neolite lamp contains just 1 milligram of mercury, according to the company, and is fully compliant with the European Union’s new Rules on Hazardous Substances (ROHS), which prohibit lead in the glass or solder of light bulbs.
For more information:
Litetronics International
Alsip, Illinois
800-860-3392, 708-389-8000
www.litetronics.com
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