LED Walls Part 2 – Let’s Talk About LEDs

What do people see when they look at a LED wall… The Light Emitting Diode of course!

So the LED was first invented in 1927, but then in 1962 a guy named Nick Holonyak, Jr. while working for GE, produced the first red LED that was then put into commercial applications.

So while the technology is not new, it has seen massive amounts of development in the past 5-10 years – so much so that it is now replacing everything from flashlights to streetlights and now in large scale video walls.

So it has taken many years to develop the additional colors and also the microscopic package that works for the current LED walls that we see and enjoy.

Today we have the SMD – which is a surface mount technology and all 3 of the colors are in one microchip. Red green and blue…

Enough history for now.

Probably the most important part of the LED wall is the LED’s themselves, as they are what we see. So the “binning” process of them is a super critical part to the quality and consistency of the image.

Binning can be thought of this way — if you bought 1 million tuning forks that were all supposed to be at 440hz, and they were not, you’d have a lot of out of tune action going on and it would not sound good. The red you see from a red LED could be one of many wavelengths within what we as humans perceive to be red. But if one is 430 and the other 450 – it will be noticed much more than if one was 440 and the other is 441.

So not only do we want the red of each LED to be the same, but we also have to contend with the blue and green being within a reasonable bin as well — as each and every SMD chip has all 3 colors. If the red and blue are spot on and the green is odd, then that LED needs to not be “binned” with the rest of the group. All three need to be within a close tolerance in order to be workable for a quality image.

Now on to another topic of particular interest. How many of you knew that LED’s have color shift? A red (or any color for that matter) LED when cool and driven at very low power vs the exact same LED warm and driven with more power will shift in its wavelength output! This has led to some manufacturers to do “hot binning” in order to see these results when driven hard.

There are multiple manufacturers of the SMD. Some of the major brands include Cree, Silan, Nationstar, Nichia, Epistar and others. Here are different price levels and also some last longer than others, but in a typical indoor application where they are run at 10-20%, and not 24/7 it’s less important than say an outdoor video billboard. The quality is important from the standpoint of their consistency.

Imagine a wall with 1 million pixels and a $0.01 difference in LED cost per unit? That is $10,000 in cost difference!

The point of all this is to take a hard look at the quality of a perspective LED wall. Many people have started to look at directly importing them from Shenzen and while it can be done, there really are no guarantees as to what you really will get. There is a lot more to look at than just the LEDs, but I will cover many more specific topics in upcoming posts.

Moving on to the types of LEDs — all commercial indoor LED walls that are to be used in the church setting should use the SMD type LED. There are signs that use the discrete RGB LEDs but I will state they are for outdoor or “sign” use in my opinion.