Tuesday, March 12, 2013

LED Sign Tech & Spec: Front Access Design Considerations for Digital Signage and Hinged Faces

-Scott Hofheins

Last year I wrote about the different access options for LED signs, and my opinions based on direct experience with each method. Today, I would like to focus on the "Front Access Face" (Hinged Face) method specifically. There are many ways to do this wrong, and only a  few ways to do it right. Poorly designed systems will cause long term safety, service, and warranty issues for the lifetime of the sign.

At first thought this seems like a great idea. Why not make the entire face open up for service? You can open the sign faster, access the component layout on a large scale, and replace parts more quickly. All of these things can be true but there are definite trade offs to be aware of. Some of these are small, but there are many potentially large factors that must be taken into consideration.

Full size hinged faces will ultimately have a size limitation. Doors that are too large will “bow” leaving the door seals away from the cabinet, allowing water entry and in some cases a skewed image. The exact size limit depends on the design, and what the manufacturer has found works best. The problem is that many manufacturers haven’t found the sweet spot, or do not care to. They are more focused on the short term sale, then the long term support of the sign. Be very careful of over-sized hinged face systems.

Water Entry
This is one of the most common failure points and a huge factor when designing and implementing a hinged face system. There are few designs in the market that address this issue fully, and most systems will have problems in the long run, if not immediately after installation. Manufacturers have found this out the hard way. The good ones have implemented solutions or moved away from hinged faces altogether. The bad ones continue to use cheaper outdated designs to hit a low price point. This has been a major issue with many of the hinge faced units designed and/or produced overseas.

Door Lifts
Something has to hold these massive doors up and it’s usually gas lifts, typically called “Gas Springs” (similar to the cylinders that hold up an SUV’s rear hatch). When the doors are too big, you have to supply a lot of "push" to safely lift them up. This means constant pressure on the door frames, pushing the faces downwards or outwards depending on the design. In some cases, the lifts have been so powerful that they can push a service tech off the ladder or bucket truck.

Hinge Strength and Design
This is another critical item in the design, and another failure point for a high number of systems. All the weight for the doors rests on these hinges, and as I mentioned earlier the gas lifts are putting a lot of pressure on the doors. When a hinge breaks, simple gravity and the power of the lifts combine to present a significant safety hazard for service crews. I've talked to service personnel in the industry who have experienced this first hand. The consequences can range from being stranded in the bucket for a couple of hours, to serious long term injuries. The quality of the hinge and the design cannot be sacrificed to save costs. Unfortunately this does happen, all too often. It’s not worth the risk in my opinion.

Bucket Access
Maneuvering a bucket underneath a large sign face is difficult, and sometimes impossible. If you have to reach components in the top portion of the sign the bucket has to be almost directly under the sign, or placed to the side to get the lift arm away from the open face. If you're working on multiple parts of the sign, this constant re-positioning can add quite a bit of time to the service call.

Internal Cables
Longer power and data cables are required to connect the internal components on the back of the sign, to the LED modules on the hinged face. Instead of running directly from the component, straight across to the LED module, they have to be run up to the top of the door, then back down on the inside. When this isn't accounted for, the wires can suffer voltage drop, and the data signal can be weak and susceptible to interference.

LED Module Replacement
While accessing the internal components might be a bit easier, replacing the LED modules can be more difficult depending on the design. In many cases you have to remove screws (or hopefully latches) from underneath the face, then awkwardly push the module out, then back through the hole. If the manufacturer has used screws to hold the modules in place, this becomes a fight against gravity and gathering dropped screws from below the sign.

In my opinion, the hinged face design has limited applications, and should be used for smaller signs and custom applications.  Although easy access to sign components is important, there is a balance to be drawn between functionality, and serviceability. When a sign is designed to function well on a consistent basis, it requires less service. I would rather have a sign that is simple to access that doesn't break down as often, than a super accessible sign that has the potential to break down more often.

I still believe that the front access design with a solid cabinet, and latched LED Modules is the ideal method for most applications. It draws the best balance between functionality, simplicity and serviceability that will support the greatest variety of applications.


I hope this post has been informative and helpful. As usual, I welcome ALL constructive comments. Please feel free to comment and add anything I've missed, or additional tips you may have regarding this topic. Please visit www.vantageled.com for many other resources, white papers, and of course: Great looking LED Signs!

**All posts/thoughts/writings are strictly the viewpoint of me and me alone and do not reflect nor speak for Vantage LED’s beliefs, attitudes, thoughts, etc. unless specifically stated.

No comments:

Post a Comment