Low-Profile Channel Letters
J. Bryan Vincent, Ph. D., Partner Principal LED
The question of how to light low-profile LED-lit channel letters keeps coming up, no doubt because they are more in demand than ever, and today there are products designed for those applications. In fact, LED modules are tremendously versatile and are available in a plethora of sizes, colors, configurations, and beam patterns today. In fact, it can be pretty confusing because of the sheer number of choices. First, let’s take a look back at LED module development.
LED “string” modules were the first widely adopted LED product in the commercial sign industry. They were originally developed to replace neon in commercial channel letter applications. At that time, most channel letters were more than five inches deep in order to accommodate neon with the appropriate standoffs from the back of the letters and still provide even illumination.
These early LED modules were typically peeled and stuck to the back of these letters and the natural beam angles of 100-120 degrees were adequate to evenly illuminate the letter without having to make any modifications to what was the commercially available standard in LED lamps (5mm, piranha, and surface mount parts). Although the LED lighting technology was still in its infancy, these LEDs offered reduced breakage and were easier to install than neon.
Although many of the “green” folks will tell you it was related to energy savings, those of us who lived through that period can tell you that while energy savings was a benefit, it was not by any means the primary driver. The primary driving force was a combination of cost, ease of manufacturing and reduced breakage.
Smaller, Better, Cheaper
As I have mentioned in previous articles, innovation in the technology sector typically revolves around three concepts: smaller, better, cheaper. LED makers followed suit and soon there were more miniaturized strings that could fit into narrow strokes. As city regulations began to limit the size of illuminated signage, it became more critical to have modules that could fit into narrower strokes.
The problem is that a channel letter sign with letters that are 6” high and 5” deep looks awkward and is difficult to fabricate. Any sign maker who has tried to get a module attached to one of the backs of these narrow, deep letters knows exactly what I am talking about.
Small Letter Solutions
I am a big believer that the market ultimately tells manufacturers what they need, and designers and architects over the past few years have demanded thinner and thinner channel letters that offer a sleek form factor. As a result, LED makers went back to the drawing boards and today there are a number of different LED “solutions” that can light a letter as thin as 1”-3” for small letters. Small letter solutions typically fall into one of three categories:
- Perpendicular Placement—One option is to place a standard 120-degree LED perpendicular to the base of the module. In this case the light is directed perpendicular to the face and washes throughout the letter. Both SloanLED’s V180 series and ILT’s Sideview series take this approach.
- Optics-Based Modules—The second approach is to use an optic. Optics-based modules work to take the native beam angle of the LED and redirect the light laterally. Many major LED modules providers such as GE (Tetra) and US LED (TD3) have adopted this approach. These systems offer the added benefit that they do not rely as heavily on the internal reflection of the letter to even out the light.
- Light Diffusing Acrylic—The third approach, which is used for ultra-thin letters (1-2”) is to take a solid piece of light diffusing acrylic and route out thin channels. A flexible LED tape strip is then placed in the channel and often silicone in place. There is some “art” to mastering this technique; however it can be a very cost effective approach. Both Principal LED and MaxBrite offer UL recognized flexible strips for these type of applications.
According to Chris Rogers, production manager at Direct Sign Wholesale, “This latest generation of LED is more accommodating to thinner channel letter returns. The modules are both brighter and have a wider viewing angle. Using the Principal Streetfighter LED modules has permitted us to install fewer modules and simultaneously maintain our demanding letter brightness standard. This is a plus for the customer because fewer modules means a lower utility bill and also less probability of any maintenance or repair issues.
“For example, we literally used to pack a large set of channel letters with LEDs. Now with the wider viewing angle from these new modules, we can achieve the same brightness and illumination coverage with a smaller module quantity,” added Rogers, whose last point is very important.
All too many sign shop owners simply ask “what is the price per foot?” when the more relevant question to the bottom line is, “What is the cost per use?” That question encompasses the total cost of the system, including assembly labor—especially in larger letter sets where the savings can really add up.
Larger multi-stroke channel letters (and single-sided cabinets and cloud signs) at very thin depths (3″-5” returns) present a different set of challenges because of three primary factors:
- Sidewall Spacing—The sidewalls are further apart, which reduces the ability for light to reflect off of the return and even out the lighting.
- Poor Diffusion—Many of these larger signs use materials other than acrylic (like polycarbonate or flex face material) which do not typically diffuse the light as well as it passes through the sign face.
- Shadowing—Often there is internal structure to provide additional support to these thinner-but-large signs that can introduce shadowing.
In these cases, products that redirect light (categories 1 and 2 above) work really well and can often save money and time over even the lowest cost non-optic module options. Let’s take a block 60” letter “A” that is 4” deep as an example. The layout was taken using the layout rules in Sign Wizard of both a batwing optic and standard non-optic LED (see Figure 1).
Evaluating Cost Per Use
The illustration in Table 1 shows a typical exercise that any sign company can go through in order to evaluate “cost per use.” As you can see, the batwing product requires significantly less material and although it is more than twice the cost per module, it actually is more cost effective to use. The counter side to this is that it will not be as bright; however, the extra modules added in the non-optic example were added to provide evenness of illumination, not to increase brightness.
Remember, this is a shallow letter and therefore the second example will provide more than enough output at the sign face. This evaluation does not take into account any extra power supplies that may be required or energy savings to the end user. Even if you put zero value on your labor time, the optics product in this exercise is a breakeven endeavor.
Again, I am not saying it works out this way every time and in the event of deeper letters (>5” deep) a non-optics solution is in many cases the better choice. However, in thin channel letters and single-sided cabinets, systems that wash light laterally can offer significant savings (both time and money) and in some cases may be the only product that works.
Large, Thin Signs
“We are trying to take optics to the next level for really large, thin LED lit signs,” according to Daryl Foreman, VP of Sales with Principal LED. “Our new Street Fighter Knockout is a high power (7W) module that uses a special LED design and can cover between four and nine square feet at depths from three and a half to eight inches with a single module.”
Mark Abernathy with US LED agrees, adding that they are taking a similar approach with their TD3 product that can be used at even shallower depths. “For shallow channel letters we are seeing more and more people go to a lensed module,” he says. “In the past when manufacturing a shallow letter people struggled with seeing hot spots from the LEDs.
“The solution to this hot spot issue used to be over-populating the letter which raised the overall cost of the project. Now with lensed products, like the TD3 from US LED, manufactures can populate shallow letters evenly without having to over populate. For instance, with the TD3 you can have a depth of three inches on the letter and still achieve even lighting with an eight-inch row-to-row spacing.”
Understanding Production Costs
One of my favorite sayings is, “Don’t trip over dollars trying to pick up nickels.” Taking the time to research what you build, understanding your real productions costs and then matching that up to a solution that is right for the application can result in significant savings and an improved bottom line.
More importantly, thin channel letters are a growing part of the market today as architects and designers demand a more streamlined image, and knowing how to properly illuminate very thin letters cost effectively can provide your company with a major competitive advantage.
This article was published in Sign & Digital Graphics magazine April 1, 2016. VIEW HERE on their website.