RGBW LEDs?

[rexxar]

My brother asked me to fix his lightsaber, and in the process of doing so, I discovered that a lot of high-end lightsabers use RGBW LED emitters. I've never heard of such a thing. I would have thought that you'd get all the colors you need with just R G and B. Or am I missing something?

(Yes, his lightsaber. The one that he spent >$200 on. He spent $200 on a lightsaber so he can go to the park with his friends and they can all hit each other with their expensive lightsabers.  )

[sleemanj]

My brother asked me to fix his lightsaber, and in the process of doing so, I discovered that a lot of high-end lightsabers use RGBW LED emitters. I've never heard of such a thing. I would have thought that you'd get all the colors you need with just R G and B. Or am I missing something?

You won't get a proper white without W.

[TheBorg]

You can get "white" with an RGB led, but it's a crappy white, and not true. There is also some light bleed from the different LEDs, as they are placed slightly away from each other, the white is not uniform, so one side of the beam will look more green or some other color.

[XOIIO]

Confirming what the other two have said, you can get "white" from an RGB LED but it doesn't look all that great compared to an actual white LED, and you can see color differences in the light based on if it's closer to one of the die than the others.

I haven't seen any RGBW LED's though, but it totally makes sense, I wonder if those cost much more. They would also probably be in the watt range.

[rexxar]

It does make sense that they're using that to get a better white. Dunno why I didn't think of it. 

[tom66]

It also allows for purer colours like pink and light blue, without expensive colour matching.

[mikeselectricstuff]

I don't recall ever seeing an RGBW LED,as the process is different for white, but RGBW LED strips using seperate RGB & white LEDs are readily available.
RGBW is good where you want lighting with a colour tint, or more subtle, pastel shades.
We used a LOT of RGBW strips for this ceiling installation
http://cinimodstudio.com/project/snog-chelsea/

[Corporate666]

LedEngin makes some RGBW LED's (LZ4 series), with a cool white 5500k die along side R, G and B.  Cree has at least one RGBW LED with the MC-E series as well.

I've tried them out but always found them rather limiting - in practice, you generally want quite a lot more power out of the white, and being in the same physical LED package as the RGB causes thermal issues.  So usually an RGB LED is supplemented with a separate white LED, or (even better) just use discrete R, G, B and W LED's in the first place.  The downside to that is it makes color mixing a pain in the ass.


Mike, that is a really cool room.  Any details on what was done and how?  I'm guessing the light is controllable in various ways?

Does it say "SNOG" on the back wall?  LOL!

[tom66]

Interestingly, I was doing a little search on RGBW drive.

Because for 100% white, the R,G,B are at 0% and W is at 100%. And for pure colour, W is at 0% and the respective colours are lit. However, in between these two you have to modulate white and R/G/B. So you need an algorithm to do this...

There's a patent on this filed in 2008 by Samsung.

http://www.google.com/patents/US8049763

So gotta be careful just in case you void yet another theory/software patent because the algorithm is really quite simple and "obvious and intuitive to anyone practicing the field" but the patent office have allowed it. 

[Frost]

We used a LOT of RGBW strips for this ceiling installation

Very interesting ceiling.
Is it a foil oder something like PLEXIGLAS LED, which was used
to cover the LED stripes?

[NiHaoMike]

There was some talk about RGBW LCDs (as in red, green, blue, and white pixels) in mobile devices as it is more energy efficient than regular RGB LCD. I think the main barrier was that GPUs are designed for RGB outputs so supporting a RGBW LCD would require too much additional processing to be viable.

[tom66]

LG's AMOLED 55"  TV uses RGBW pixels.

[Towger]

Are they colour mixing the LEDs in the ceiling to get the overall colour close to white?  In any event it looks like the designer was a fan of the magic roundabout...

[mikeselectricstuff]

Each of the long stripes has a "ladder" of lateral RGBW strips behind it, all individually controlled - from memory I think there were about 1000 control channels. the surface is a heatshrunk plastic film called barrisiol http://www.barrisol.com/

[tom66]

How much power does such a setup use? Any cooling issues?

[rexxar]

Because for 100% white, the R,G,B are at 0% and W is at 100%. And for pure colour, W is at 0% and the respective colours are lit. However, in between these two you have to modulate white and R/G/B. So you need an algorithm to do this...

There's a patent on this filed in 2008 by Samsung.

Oh that's just fucking ridiculous.

And our politicians think the patent system is just fine. Of course, that's mostly because they're being paid off by huge companies like Disney.

[Psi]

If only i could get a patent on the act of complaining about patents.