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How to Eliminate Hot Spots and Shadows in LED Signs

Written by Mallory Young

Jan 5, 2022 4:59:06 PM

 

It’s 3:30pm. Your team just finished a new sign and it must ship tomorrow. Like the good sign maker you are, you check the make sure it works properly...and whoop…there it is! A hot spot...

You did everything you normally do and followed the layout you were provided. And yet, right there, going north to south, diagonally down the center of your sign, a big ugly shadow. “But it’s 2021! Shadows should be a thing of the past!” you say.

Well, you are right. With the development of LED optics these days, shadows and hot spots should be a thing of the past. And that is just it. Maybe it is not your LEDs. Maybe, it is the sign face? Maybe, it is the structure in your sign?

Over the years, through years of in-the-field experience, our team has learned a few tricks-of-the-trade that will help the next time that shadow gives you trouble. Outlined below are a few simple solutions to the lighting challenges you may experience from time to time. 

 

Lighting Challenge Number 1: Tension Rod Shadows in Cabinets

The day that light first dawned on this Earth, so too was the first shadow cast. Shadows happen. Tension rods, center poles, support beams, and other internal structures are like a person who sits in front of you at the movie theater blocking your view. These structures in a sign each present unique challenges when it comes to even illumination. For instance, light bouncing off a gloss backer creating unwanted glares; multiple shadows appearing across the face, caused by a ¼” tension rod. Seriously! how does something that small create such a big problem?  

Back in the day, cabinets were lit with fluorescent or HID lamps. These lamps allowed the light to spread 360 degrees and have a dance party inside the sign, bouncing in and around tension rods before the light escapes through the face. 

However, nowadays people are retrofitting signs with LED sticks to save costs and energy. LEDs typically have a 175° beam angle shooting directly towards the face, creating a shadow when tension rods and support beams are present. Blocking light is cool if you’re an MLB Short Stop diving to snatch a line drive hit up the middle…. but not when it’s a $25,000 sign that you’ve spent that past month building to perfection.

 

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However, when you are in the field and you don’t have the luxury of your shop to change things around, here are a few tips that we call “the simple fix”.

  • Bring your LEDs in front of the tension rod. If you can mount your LED sticks closer to the sign face, and in front of the tension rod, that’s the ultimate fix. Just remember that that the closer you bring your LEDs to the sign face, the closer you might have to space your rows of LEDs to prevent Hot Spots (see below). Fortunately, because of the innovative optics & wide beam angles of the PhoenixNRG Bars and Kestrel Sticks from HanleyLED, you can get very close to the face while still retaining the industry’s best spacing,
  • Bring your LEDs as close to the tension rod a possible. Because of the wide 170° and 180° lenses of our popular PhoenixNRG, Kestrel & Wingspan families, bringing your LEDs closer to the tension rod allows the light beams to shoot around the front structure, creating a curtain of light that prevents the shadow. Try this at home! Take a standard household flashlight and aim it at the wall as you stand 3ft away from the wall. Hold your hand perpendicular to the flashlight’s beam (as if you are karate chopping the light), about 6-12” in front of the flashlight. Notice the big shadow? Now bring your hand closer and closer to the flashlight and notice how the shadow gets smaller and smaller, the closer to the light source your hand gets. This is the same effect as bringing the tension rod as close to your LED light source as possible.
  • Electrical Tape. What if you cannot mount your light bars closer to the face, you ask? Look no further than your toolbox and take the “simple man” approach! Use black electrical tape. Placing the tape over the LED modules that are directly behind the tension rod eliminates the light source that is causing the shadow. And since you are only eliminating 1 module per row, and because the HanleyLED PhoenixNRG Bars, Kestrel Sticks & Wingspan families (whichever if your favorite) all are incredibly bright because they each utilize High Efficiency LED technology, the surrounding modules are more than enough to light your sign.

 

“The best way to prevent a problem is to never get into it in the first place.”

- Water Polo Coach, Don Casey.

 

Lighting Challenge Number 2: Hot Spots

There is nothing worse than seeing individual LEDs dotting the face of a sign. These dots, also known as hot spots, occur when modules are spaced too far apart. An LED module’s ideal spacing is determined by several factors: quality of the optics (aka: lens) on your module, depth from the face, diffusion characteristics of your sign face (ie: Acrylic vs Polycarb vs Flex Face vs Economy Flex Face). Remember Coach Casey’s advice above? “The best way to prevent a problem is to never get into it in the first place.” Don’t forget it! Choosing an LED with superior optics (without overpaying of course) will prevent hot spots even if you don’t follow your LED layout perfectly.

How do hot spots happen? It occurs when your light hit the sign face before the beams of light can cross each other.   It is important that the light beams overlap before reaching the face of the sign to ensure even illumination. The wider the beam angle of your lens (such as the 170° beam of the HanleyLED PhoenixNRG family or the 180° beam of the Kestrel Family of modules & sticks), the more likely your light beams will cross before hitting the face. And not only do these wide beam angles help prevent hot spots, but they also give you the versatility of bringing your sign face closer to the LEDs, making it possible to make signs as shallow as 2” deep. Using a diffuser film on the face will help combat hot spots.

 

How to find the right spacing for HanleyLED modules

Here are a few helpful tools available on Hanleyledsolutions.com

 


For more LED and Electrical Sign education, check out HanleyLED's Jolt the Volt Podcast on YouTube! The podcast provides educational How-To's and best practice suggestions for everyday electrical signage solutions.

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