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LEDs suit outdoor signs, signals

Posted: 17 Nov 2005     Print Version  Bookmark and Share

Keywords:agilent technologies  led  aluminum indium gallium phosphide  alIngap 

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Agilent Technologies Inc. said it has introduced the industry's brightest 5mm LEDs for outdoor electronic sign and signal applications. The new, mid-power red (630nm wavelength) and amber (590nm wavelength) lamps also provide more than double the current rating of previously available extra-bright lamps.

Supplied in 5mm (T-1 34) domed through-hole packages with oval radiation patterns, this new series of aluminum indium gallium phosphide (AlInGaP) LEDs can operate with currents as high as 70mA, compared with 30mA for Agilent's extra-bright oval lamps. This provides a substantially higher light output than conventional 30mA lamps, with the red lamps offering 3,309mcd typical luminous intensity and the amber lamps at 2,521mcd, both being driven at 70mA forward current.

Agilent explained that the oval-shaped radiation pattern provides a wider field of view with higher luminosity than standard LEDs, which make the devices well-suited for outdoor applications where readability in sunlight is essential. These mid-power lamps have very smooth, matched radiation patterns that ensure uniformity across the viewing angle of the sign or signal, said the company.

For designers, this means two things. They can design in fewer discrete LEDs to provide equivalent brightness. Or signs can be designed with the same number of LEDs, and still provide substantially higher brightness levels for better readability and contrast. Since the lead spacing and packages are compatible with conventional high-brightness 5mm oval-pattern LED lamps, the upgrade requires no mechanical changes, said the company.

Two viewing angles are available for different applications. With an angle of 30-by-700, the red HLMP-AD31-UX000 and HLMP-AD30-UX000 (with and without lead standoffs, respectively), and amber HLMP-AL30-TW000 and HLMP-AL31-TW000 (with and without lead standoffs) are generally used for long-distance viewing in applications such as traffic signals.

With a viewing angle of 40-by-1000, the red HLMP-HD31-SV000 and HLMP-HD30- SV000, and amber HLMP-HL31- RU000 and HLMP-HL30-RU000 (with and without lead standoffs) are used for wide-viewing-angle applications such as stadium scoreboards and other message signs.

These mid-power AlInGaP lamps are supplied in Agilent's precision optical performance molded packages, which are modified for higher current input and increased heat dissipation. The die is attached within the reflector cavity, and the cavity is encapsulated by an Agilent proprietary ultraviolet-resistant epoxy blend. The combination of all packaging factors allows the devices to operate over the temperature range of -400C to 850C temperature and provides protection from UV-A and UV-B ultraviolet radiation and humid environments.

Pricing of the mid-power oval-pattern LED lamps is 18 cents each in quantities of 1 million. Samples and production quantities are available now with a four-week guaranteed lead time.

- Gina Roos


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