Illumination: Optimizing LEDs for signage

When LEDs first reached sign shops, they were most suitable for use inside channel letters. Photo courtesy SloanLED

When LEDs first reached sign shops, they were most suitable for use inside channel letters.
Photo courtesy SloanLED

Increasing versatility
With such developments, LEDs have also become practical for more types of signs today than they were in the early 2000s.

“LEDs are unidirectional, so when they first reached the sign industry, they were most suitable inside channel letters, where you only need lighting in one direction,” says Mike Bluhm, North American sales manager for SloanLED, which has served the lighting industry since the mid-1950s and specialized in LEDs since the early ’70s.

As a design and engineering firm, SloanLED was also well-positioned to apply past lessons
to the customization of LED systems for the
sign industry.

“We came up with ‘poster box’ LEDs for wall signs, where side illumination is used to achieve even lighting within a very shallow profile,” says Bluhm. “We’ve also placed LEDs at angles to bounce their light off the sides of channel letters and used secondary optics to bend light in more visually appealing ways.”

“Each LED module and system has a different application, depending on sign depths and angles, and you have to educate people about how to use them, so as to optimize performance and reduce costs without sacrificing brightness and uniformity,” says Global Lux’s Vilanova. “You also need good wiring. Many manufacturers today provide high-
quality LEDs, but they all use different connectors.”

Also, as these systems have been introduced, signmakers have responded by specifying shallower profiles in the first place. With LED-based signs running cooler and taking up less space than their predecessors, they can be installed in places that would have been difficult to illuminate before.

“Perimeter lighting with LEDs allows for easier installation of accessibility signage versus conventional fluorescents,” says Bluhm.

The development of white LEDs was a major step forward for the sign industry.  Photo courtesy US LED

The development of white LEDs was a major step forward for the sign industry.
Photo courtesy US LED

New horizons
That said, some types of sign illumination have proven challenging or even impossible for LEDs to achieve, particularly at the larger, brighter end of the spectrum.

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“We struggle to compete with the high-intensity discharge (HID) lighting that’s installed inside big pylon signs or blasts onto a billboard at night,” says Bluhm. “Those are cases where you need a lot of light across a lot of space.”

Similar problems are encountered across large flex-face signs that rely on tension bars running their entire length to help maintain their structural integrity.

“Extrusions have been redesigned to bring the tension bars back a bit, but they still allow shadowing if you’re using LEDs,” says Bluhm. “They’re hard to light evenly.”

Where there is still much opportunity for LEDs, however, is in the replacement of fluorescent lighting, which is still common across the sign industry.

Improvements in lens design have helped LED modules create more even illumination across sign faces. Photo courtesy Global Lux

Improvements in lens design have helped LED modules create more even illumination across sign faces.
Photo courtesy Global Lux

“LEDs are still more expensive than fluorescent, but will shine brightly much longer,” says Bluhm. “A fluorescent lamp depreciates quickly from day one.”

With this in mind, he cites growing efforts to use LEDs to illuminate dye-sublimated fabric graphics in the retail sector, particularly to help reduce maintenance costs for those installed at hard-to-reach heights.

“The focus will be on replacing fluorescent lighting in sign boxes,” Global Lux’s Vilanova agrees. “There are only a few LED systems like that now and they’re still quite expensive, so there’s still a lot of market opportunity.”

With files from Global Lux, US LED and SloanLED. For more information, visit www.global-lux.com, www.usled.com and www.sloanled.com.

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