One of the benefits to using LEDs for illuminating signs is that because of the lower voltage required, they are more accessible to sign shops than other lighting sources, and the regulations covering fabrication and installation may be less strict than with either fluorescent or neon lighting. However, before the average non-electric sign shop ventures into the illuminated sign market by using LEDs in channel letters, backlit cabinets or edge lit displays, they should be comfortable working with electrical systems and have all the proper licensing and permits required by your local government as well as UL-listed materials where required.And while it is true that any sign shop can purchase LED modules from one of the many manufacturers and suppliers out there and mount them in an illuminated sign, there is much more to designing an efficiently and evenly lit sign that will make your clients look good for many years to come. Knowing proper LED layout can save a shop money by making sure it only uses the perfect amount of LEDs. Even a full-service electric shop can benefit from knowing a few design tricks.

Edge lit graphics add light and dimension to graphic displays, without requiring a bulky cabinet to hold the LEDs.

To get some advice on the proper spacing recommended to achieve the most even and consistent lighting in various types of illuminated signs, I spoke with Jill Bonilla of SloanLED, Kerry Moore, LEED AP of CAO Group, Jeff Snider of Signs A Glow, and Charlie Abrams of Access Display Group.There is no standard minimum or maximum distance between LED modules recommended, because it depends on the shape and depth of the cabinet or housing, the type of application, the distance from the graphic, the viewing angle or cone of light cast by the LEDs, the color of the LEDs, the ambient light situation, and the type of acrylic and diffusion panel used. Most LED suppliers will assist you with these areas. For example, SloanLED provides density guideline charts and pricing calculators on their website to aid signmakers in determining the number and placement of LEDs and power supplies required for their projects. If you send a file with your vector artwork to info@SloanLED.com or layouts@caogroup.com, they will send your file back populated with the correct type, quantity and spacing of LEDs recommended, plus a full bill of materials.

In general, with backlit graphics it is important to use only sign-grade acrylics and high-performance translucent vinyl to avoid hot spots. With a shallower cabinet, you will need to use an LED with a wider viewing angle, from 120 to 180 degrees. Bonilla says SloanLED has developed a 180 degree LED module, with the diodes mounted in a pyramid configuration. LEDs with wider viewing angles and lighter colors can also be spaced further apart, requiring fewer modules to fill the cabinet with light. However, the cone of light should be even, with no brighter centers or dimmer edges, and the modules must be spaced so that the cones overlap. Blue acrylic is difficult to light, and will require denser, brighter illumination.

This small display is lit only from the bottom edge, with LEDs housed in the base, allowing the material to be cut to a custom shape.

The same sign seen in a different light shows how the engraving creates a brightly glowing graphic, even in a bright environment. Surface textures and engraving can be used to great effect when illuminating the material from the edge.

Correct spacing of CAO Group’s Blaze LED modules will result in even, bright illumination of channel letters or backlit cabinets.

Deeper cabinets often need more modules closer together, with narrower viewing angles to focus the light more intensely on the back of the graphic. For every foot of distance, the intensity of the light needs to be four times greater. Halo lit letters should be shallower, bringing the LEDs closer to the wall with a wider viewing angle to throw the light out the sides of the letters.

It is possible to make an evenly and brightly backlit cabinet as shallow as 2" with the right materials, the correct placement and type of LEDs. Bonilla says SloanLED provides a list of vinyl and acrylic manufacturers paired with the best LED module design, colors, and spacing to use with each one. Kerry Moore of CAO Group advises that the color of the LEDs will also affect the perception of the colors in the backlit graphic. Warmer white in the 3500 Kelvin range will make warm colors look more vibrant, but a cooler colored graphic will look much better with a cool white in the 6000-9000K range. Warm and cool white LEDs can be combined to illuminate a graphic with both cool and warm colors, and Morre says CAO Group will also recommend the best color temperature to use for your project.

EDGE LIT GRAPHICS
SloanLED makes a ThinLED module in an array of colors that can be used for edge lit graphics. CAO Group does not make recommendations for edge lit design. The design requirements for edge lit displays are very different from backlit, from the LED modules to the housing to the handling of the acrylic panels and graphics.

Since the light travels parallel with the acrylic or glass surface, the quality of the transmission material is very important. The LEDs can be glued directly to the edge of the acrylic, as is the case with Swingframe displays manufactured by Access Display Group, but the correct type of adhesive must be used to transmit light without bending the waves. A shiny, smooth edge will actually reflect some of the light away, while an etched edge will transmit it more efficiently.

Jeff Snider of Signs A Glow explains that the LED diodes can be mounted ¼", ½" or 1" apart on strips wrapped around the edge of the acrylic. A smaller surface area can use a wider viewing angle of 120 degrees, with the LEDs mounted on only one edge of the acrylic. Larger graphics will need a narrower beam to cover a longer distance, and may need LEDs mounted on two or all four edges. Really large displays may require the acrylic to be seamed, which will break the light beam and create a glowing white line. In that case, a strip of black vinyl along the edge will solve that problem, but of course, the other half of the acrylic will need to be illuminated from the other side.

LEDs can be used to create halo lighting and glowing edges in channel letters, and a shallower channel is actually more effective.

SloanLED achieves a 180 degree viewing angle by mounting their LED diodes in a pyramid form.

If the face of the acrylic is etched or engraved, the beam will be interrupted and the edge of the engraving will glow brightly. The intensity of the light will be diminished as it passes through the engraved surface, so images in the center will not be as bright as those at the edge. Similarly, the slightest scratch or change in the surface tension will be illuminated; even fingerprints will glow quite obviously, and you will never be able to eliminate the ghosts of vinyl graphics that have been removed.

The type of acrylic used is very important for light transmission. Extruded acrylic is not clear enough to transmit light efficiently. Cast acrylic is better, but microsphere acrylic has tiny beads embedded throughout that spread the light evenly across the surface. The cost is much higher, but for larger areas it may be worth the investment. Access Display Group uses a matrix of lines that carry the light across the panel or “Endlighten” self-illuminating plastic. The thickness of the material does not affect light transmission, so there is no reason to use ½" thick acrylic when ¼" will do. For larger panels, it may be necessary to use 3/8" thick material to minimize sagging.

The minimum depth of the cabinet is determined by the thickness of the material and the dimensions of the LED strips. A 1" deep housing is adequate to hold the modules and acrylic panel, plus a diffuser panel behind the graphic, which can be paper, styrene, or any matte white surface that bounces light forward.

It is also important to choose the right kind of power supply to light the LEDs efficiently without overloading them. Magnetic power supplies must be carefully matched up with the total length of LED modules. If overpowered, the LEDs will burn out, and if underpowered, the power supply will burn out. Regulated power supplies cost more, but will only draw the amount of power needed and will not burn out due to overload. Different colored LEDs also draw different wattages, with white being the highest.

Swingframe displays combine the latest in thin-edge light panel technology with the simplicity of the patented swing-open display system that offers a variety of metal and wood profile styles.

The LEDs available on the market come in three different grades: A (military), B (electronics, phones, and computers), and C (toys and inexpensive signs). Manufacturers and suppliers come and go, and there is a lot of competition in the market, with the lowest prices and the lowest quality coming from China. LEDs manufactured in Korea, Japan and the U.S. tend to offer more dependable quality and customer service, so be careful to check out the source thoroughly.

As with any advancement in sign technology, new developments are in the works and the market is constantly changing. If you plan to include LED illuminated signs in your shop’s product offerings, do your homework and take advantage of the resources and advice that is available from those who are LED-ing the way.