RGBW LEDs? - Page 1
Forum section: electronics / general

author: rexxar
author_rank: Frequent Contributor
timestamp: January 30, 2014, 06:46:12 am
content: 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 RGBWLED 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.)

author: sleemanj
author_rank: Super Contributor
timestamp: January 30, 2014, 06:52:51 am
content: Quote from: rexxar on January 30, 2014, 06:46:12 amYou won't get a proper white without W.

author: TheBorg
author_rank: Frequent Contributor
timestamp: January 30, 2014, 07:05:52 am
content: 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.

author: XOIIO
author_rank: Super Contributor
timestamp: January 30, 2014, 07:19:15 am
content: 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.

author: rexxar
author_rank: Frequent Contributor
timestamp: January 30, 2014, 07:30:30 am
content: It does make sense that they're using that to get a better white. Dunno why I didn't think of it.

author: tom66
author_rank: Super Contributor
timestamp: January 30, 2014, 11:25:33 pm
content: It also allows for purer colours like pink and light blue, without expensive colour matching.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 30, 2014, 11:53:17 pm
content: 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 installationhttp://cinimodstudio.com/project/snog-chelsea/

author: Corporate666
author_rank: Unknown
timestamp: January 31, 2014, 12:45:40 am
content: 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!

author: tom66
author_rank: Super Contributor
timestamp: January 31, 2014, 01:10:04 am
content: 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/US8049763So 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.

author: Frost
author_rank: Regular Contributor
timestamp: January 31, 2014, 01:14:40 am
content: Quote from: mikeselectricstuff on January 30, 2014, 11:53:17 pmVery interesting ceiling.Is it a foil oder something like PLEXIGLAS LED, which was usedto cover the LED stripes?

author: NiHaoMike
author_rank: Super Contributor
timestamp: January 31, 2014, 01:52:38 am
content: 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.

author: tom66
author_rank: Super Contributor
timestamp: January 31, 2014, 05:02:43 pm
content: LG's AMOLED 55" TV uses RGBW pixels.

author: Towger
author_rank: Super Contributor
timestamp: January 31, 2014, 07:15:18 pm
content: 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...

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: January 31, 2014, 07:24:44 pm
content: 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 barrisiolhttp://www.barrisol.com/

author: tom66
author_rank: Super Contributor
timestamp: January 31, 2014, 10:19:45 pm
content: How much power does such a setup use? Any cooling issues?

author: rexxar
author_rank: Frequent Contributor
timestamp: January 31, 2014, 11:17:03 pm
content: Quote from: tom66 on January 31, 2014, 01:10:04 amOh 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.

author: Psi
author_rank: Super Contributor
timestamp: February 01, 2014, 02:04:38 am
content: If only i could get a patent on the act of complaining about patents.