Signage: from the incandescent lamp to led letters

Advertising is illuminated around the clock—so it is hardly surprisingly that its illumination has become increasingly energy-efficient. But this development is always posing new challenges for the material to be used. In this area, PLEXIGLAS® offers excellent possibilities for energy-efficient lighting.

As early as in the Roaring Twenties, the centers of the first global metropolises were brightly lit with illuminated signs. In the 1950s, incandescent lamps in illuminated advertising were then very largely replaced by the even brighter—and later also formable—fluorescent tubes. “At this time, acrylic clearly took over as the leading material for illuminated outdoor advertising,” says Matthias Schäfer, the expert in charge of the Visual Communication & Lighting segment at PLEXIGLAS®, “because it was able to diffuse light uniformly.” Since that time lighting engineering—as also signage—has continued to develop, initially through ever more efficient and smaller fluorescent tubing, and subsequently by way of light-emitting diodes (LEDs).

More efficient illuminants

“Signage has become more energy-efficient over the years,” says Schäfer. “And every new illuminant changes the design of illuminated signs and lettering.” Until just a few years ago, for example, fluorescent tubes still dominated illuminated signage. They were installed in light boxes behind the surfaces to be illuminated—or were formed and inserted into the cavities of machined or bonded plastic letters. “But this design can’t simply be adopted without modification for energy-saving LEDs,” says Schäfer.

PLEXIGLAS® makes a mark

Today, advertising structures made of Evonik’s brand acrylic glass shine around the globe, as here in Leipzig (Germany). The 12-meter-high, illuminated ball with an outer layer made of PLEXIGLAS® LED is the distinguishing feature of the Nova Eventis shopping center. It glows in red, green or blue as selected.

Avoiding brightness differences

The reason is that LEDs radiate a strongly focused light, as a result of which unwanted brightness differences, known as hot spots, could arise. LED-operated advertising structures therefore need a material that diffuses light very well for the advertising messages to be visually impressive. “Due to the use of LEDs, the requirements placed on materials for illuminated advertising have increased,” says Schäfer. “Only the right combination of illuminant and surrounding material leads to efficient illuminated signs with minimal energy costs.”

Materials for illuminated signage

For these special requirements of LEDs, PLEXIGLAS® LED is the branded acrylic of choice. One variant is particularly suitable for light boxes backlit with LEDs, the LEDs being mounted across the entire area behind the light-diffusing material. In addition, the colored grades of PLEXIGLAS® LED are tailored to the same wavelength regions where red, yellow, green, or blue LEDs are illuminated. “In this way these colored LEDs are optimally used and the system shines more brightly for the same energy input,” says Schäfer. PLEXIGLAS® LED for backlighting also has better light-diffusing properties than conventional acrylic. “The use of LEDs makes compact light box design possible—and that in itself means that undesired hot spots are largely avoided,” says Schäfer.

Identical design around the world

PLEXIGLAS® can be easily dyed, enabling an exact representation of a company’s color scheme. This ensures that all the advertising boards of all the branches worldwide look the same. The selected color remains unchanged, regardless of whether it is illuminated or not.

Block material for lettering

PLEXIGLAS® LED Block has been specially developed for particular market requirements. “The market knows this product as full acrylic letters that have proven their worth especially for illuminated lettering in sizes up to 500 mm,” says Schäfer. And because PLEXIGLAS® is naturally UV-resistant, logos as well as large advertising signs retain their colors and high-quality appearance over the long term, and can be used for many years—for energy-efficient and sustainable illuminated advertising.