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RGB signage and photography

Eric B

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I've long been interested in RGB LED technology, because of the potential to creat full color signs on trains. http://www.erictb.info/interests.html#LEDs It was the R110A that really helped spark this off, but it of course did not ave blue, which was the last color to be added. within ten years, it would finally appear, but Transit went with single color LED's n signs, and stuck with the old red-yellow-green for interior signs and the Platform Information Signs.


Part of the problem with RGB's is the wide pitch (space between pixels) required because of thermal issues that prevent them from being safely placed close to each other. They even tried them on the ad signs on the outside of station (and later replaced these with LCD's), and then on as ad signs on a few articulated buses. So they have been slow in appearing on small information signs.

Now, they have finally begun appearing on Lotto machine jackpot signs!


While most RGB signs use a rich "pure green", this one uses the old yellow green. That is cheaper, because the new pure green and blue use Gallium Nitride, which is the new technology making the lower wavelegnths possible. So I had been suggesting Transit to use this kind, as anyway, for the BMT/IND, the yellow green matches the (G) color.


The pitch is a little bit smaller than other RGB's, but still a bit wider than other LED signs.


Here is a picture in close to its true colors


Because of the yellow-green, the colors are off, with the "white" as a sort of lavender. (The "S" in the example; or maybe it's the "E", which does have a pinkish tint, perhaps faded by the photography and computer screen. In real life, it looks more like the "S". And the "A" is the primary green).


But in my video, the lousy phone camera video quality totally distorts all the colors. (though notice, all the opaque object colors look fine!) I really don't even know which is which there. I know I saw the three primary colors, red (635 or more nm), yellow-green (565), blue (470?), and then magenta, lavender, amber and a pale cyan. It was probably supposed to be the basic 7 colors RGB's often display: RyGcBmw, though again, the white is lavender and the yellow is amber.

In this video, lavender, magenta, cyan and blue all look like the same cyan shade, and I'm not sure whether or not the green is also one of them, or the paler amber. The deeper orange has to be the red!


So phone cameras are really this bad with colored light? I don't take much photography, so I'm basically new to this


Anyway, it looks like RGB is finally catching on! I just wish Transit would catch on to them!

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