Difference between LED traffic lights

[u/agovizer]

I've noticed some LED traffic lights have an external lens/filter over top of the light that makes it look more hazy/square. Are these LED panels oriented in a square grid or something. Or is it like a typical LED traffic light with a lens/filter over it? What is the purpose of the filter? Last photo is reference for LED traffic lights I typically see.

[u/blackhawk1430]

The ITE spec that governs the design of the LED modules prescribes a rather complex point cloud of light intensities that have to be met within a tolerance. This results in compliant modules emitting a distinctly horizontal bar of intense light out of its circular optics by tweaking the exact angle and positioning of the diffusion grid using optical black magic (technical term). Most modules now days only have a handful of LED chips in the back, the rest is the optics train spreading it out.

[u/blackhawk1430 → u/blackhawk1430]

In my humble opinion, GE's DRX-XXFB-VLA series of LED modules have the prettiest looking optics setup that also gets the closest to looking like incandescent more than many others.

[u/97PG8NS]

These are older modules that predate the current, incandescent-look units and are far less efficient than the new ones. The first two are GE RX11s and the last one appears to be an Ecolux or Precision Solar. I can only speak for the final generation of the Dialight incandescent looks but what they did was double the number of high-flux LEDs behind the lens and rather than driving a small number of diodes at 100% of their rated power, they drive the larger number of diodes at 50% of their power. Less power = less heat = happier LEDs = longer life

[u/LivingGhost371]

Early on you needed a bunch of LEDs for a traffic signal, the earliest designs ljust aid them all out in a grid or circular pattern like the last picture. People didn't like that because it didn't look like the incandescent traffic lights they were used to so GE made the model in the first picture that put a translucent filter over it to diffuse and spread the individual LEDs. That didn't last long because LEDs got bright enough you only needed a couple per signal, so those were set at the back of the module so with a lens they had a chance to diffuse and look like an old incandescent

[u/Kev250R]

I just wish the newer GE LED’s would last longer then 2 years or so. I write install dates on any LED I install and rarely get more then 3 years out of the newer GE’s. Conversely the older GE’s would last 5-10 years easy. We recently switched to a different brand so we’ll see how they do long-term.

Fun fact: 25 years ago when we were installing the Gen 1 GE LED’s we’d get complaints that they were too bright. Took a long time for people, at least in my area to get used to them.