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Thread: Koito's new red phosphor

  1. #1
    Moderator Alaric Darconville's Avatar
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    Thumbs up Koito's new red phosphor

    Koito (the famed Tier 1 supplier to such as Toyota) is at it again, with a new red phosphor high-CRI white LEDs. It's called "Fluorine Oxygen Ligand Phosphor", or "FOLP:Eu2+".

    http://techon.nikkeibp.co.jp/atclen/...5mk/011101836/ shows the sciency bit, but in short most white LEDs are somewhat deficient in red output, which makes higher CRIs difficult to attain.

    This could mean that one day we have warm-to-neutral (or even strictly neutral) LED headlamps with high luminous efficacy and high CRI. Perhaps this could mean that existing 6000+ CCT LED headlamps will look antiquated and be undesirable, and soon we won't have to deal with all that "just like daylight" handwaving that is the current marketing spiel.

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    Flashaholic* FRITZHID's Avatar
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    Default Re: Koito's new red phosphor

    That would be nice to see. Tnx for the link
    I Got tired of looking for the light at the end of the tunnel so i lit that bitch up myself! Convoy s2 365nm, Maxa-Beam Gen II, 55w hid/100w incan Vector Twin, Amondotech n30, vss-3A, Reylight Ti Lan v3, Helius Sigma 9, astrolux s41 219, Shadow JM35, BLF GT,

  3. #3

    Default Re: Koito's new red phosphor

    Not only for automotive, but also for home and commercial lighting, that is a very promising development! So is Seoul Semiconductor's purple-based (rather than blue-based) SunLike LED technology.

    Now all we have to do is wait for these to make their way into LEDs appropriate for building headlamps around. I hope it happens. A lot of the objections to high color temperature (your 5500K, 6000K, 6500K types of ranges) will probably fall away once that giant blue peak in the spectrum gets chopped off.

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    Moderator Alaric Darconville's Avatar
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    Default Re: Koito's new red phosphor

    I only hope the marketers latch on to this in such a way as they can paint the high-CCT LED sources as being just so much antiquated rubbish, and for REAL luxury/sport/race cars you gotta have this new technology that cuts "harmful blue light" or whatever...

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    *Flashaholic* PhotonWrangler's Avatar
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    Default Re: Koito's new red phosphor

    Interesting. Thanks for the link! I'm looking forward to seeing commercial lamps based on this phosphor blend.

    It looks like the excitation wavelength is centered around the 400nm violet wavelength. I recall that GE was experimenting with violet excitation and different phosphor blends under their VioLed banner. I don't know whether they've tried this specific phosphor, but they did manage to commercialize it, although I don't think it really got much traction in the market.
    Last edited by PhotonWrangler; 02-03-2018 at 12:21 PM.

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    Moderator Alaric Darconville's Avatar
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    Default Re: Koito's new red phosphor

    It just occurred to me that one killer app would be a white 921 which would be great for a reversing lamp, or would work very well behind the red lens of a CHMSL.

    It may be some time before they license this formula, though.

  7. #7

    Default Re: Koito's new red phosphor

    No exotic new phosphors or new technologies are needed to make white LEDs that work behind red lenses. Those already exist.

  8. #8

    Default Re: Koito's new red phosphor

    Whats the point in that in way? Why don't you just use a red LED?

  9. #9
    Moderator Alaric Darconville's Avatar
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    Default Re: Koito's new red phosphor

    Quote Originally Posted by -Virgil- View Post
    No exotic new phosphors or new technologies are needed to make white LEDs that work behind red lenses. Those already exist.
    True, but they're not being made in the 921, at least for our market, for some reason. Maybe this could lead to them just because it's so "high-tech".

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    Moderator Alaric Darconville's Avatar
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    Default Re: Koito's new red phosphor

    Quote Originally Posted by Magio View Post
    Whats the point in that in way? Why don't you just use a red LED?
    Ask Peterson Manufacturing, who use white LEDs behind red lenses in their LumenX line.

  11. #11

    Default Re: Koito's new red phosphor

    We chose white diodes over colored diodes for their superior thermal management –– they don’t lose intensity
    Ehh...maybe they got some special LED but I have not seen a white LED that didn't loose intensity, just like a colored led. Maybe the percentage decrease is less or something like that but it does still loose intensity.

  12. #12

    Default Re: Koito's new red phosphor

    Quote Originally Posted by Magio View Post
    Ehh...maybe they got some special LED but I have not seen a white LED that didn't loose intensity, just like a colored led. Maybe the percentage decrease is less or something like that but it does still loose intensity.
    Or maybe the R&D department at Peterson has "seen" (rigorously tested) more LEDs than you, and they specified ones that don't lose intensity at the drive currents used and with the heat sinking provided.

  13. #13

    Default Re: Koito's new red phosphor

    I was always under the impression that the brightness of an LED was directly or indirectly related to its temperature and any change in temperature, however small it may be, meant a change in brightness however small it may be. Are you saying that is not true?

  14. #14

    Default Re: Koito's new red phosphor

    Quote Originally Posted by Magio View Post
    I was always under the impression that the brightness of an LED was directly or indirectly related to its temperature and any change in temperature, however small it may be, meant a change in brightness however small it may be. Are you saying that is not true?
    No, I'm pretty sure I haven't said that. But you could double-check this thread; if you see me saying that, go ahead and point it out. :-)

  15. #15
    *Flashaholic* PhotonWrangler's Avatar
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    Default Re: Koito's new red phosphor

    Brightness is affected by the amount of current flow, however like any semiconductor, there is a saturation point where any further increase in current won't produce more brightness, only damaging heat.

  16. #16

    Default Re: Koito's new red phosphor

    Quote Originally Posted by PhotonWrangler View Post
    Brightness is affected by the amount of current flow, however like any semiconductor, there is a saturation point where any further increase in current won't produce more brightness, only damaging heat.
    Exactly. But it's my understanding that at any level of current flow, no matter how small, there will be a certain amount of heat generation. This heat generation leads to the led becoming slightly less efficient at producing light than it was when it's tempature was lower so the lumens drop until the temperature settles at a given level. If that is true I don't see how Peterson can claim that their LEDs don't loose any intensity. Virgil's post is so confusing and seemingly sarcastic with the smilie face I don't know what he's saying.

  17. #17

    Default Re: Koito's new red phosphor

    Quote Originally Posted by Magio View Post
    it's my understanding that at any level of current flow, no matter how small, there will be a certain amount of heat generation.
    True.

    This heat generation leads to the led becoming slightly less efficient
    Above a certain point, yes, but you're ignoring or leaving out thermal management, that is the degree to which the LED is able to shed heat because it has been provided with adequate heat sinking in the design and construction of the lamp assembly, thus keeping the junction temperature below the temperature where output begins to droop.

    I don't see how Peterson can claim that their LEDs don't loose any intensity.
    Simple: they didn't ignore or leave out thermal management.

    Virgil's post is so confusing and seemingly sarcastic with the smilie face I don't know what he's saying.
    Among other things: THE WORD YOU'RE TRYING TO USE IS SPELLED L-O-S-E, WITH ONLY ONE "O". I typed that in uppercase letters so it would be nice and clear for you. :-)
    Last edited by -Virgil-; 02-04-2018 at 06:11 PM.

  18. #18
    Moderator Alaric Darconville's Avatar
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    Default Re: Koito's new red phosphor

    Originally posted by Magio
    This heat generation leads to the led becoming slightly less efficient at producing light than it was when it's (sic) tempature (sic) was lower so the lumens drop until the temperature settles at a given level. If that is true I don't see how Peterson can claim that their LEDs don't loose (sic) any intensity. Virgil's post is so confusing and seemingly sarcastic with the smilie face I don't know what he's saying.

    What does "so the lumens drop until the temperature settles at a given level" even mean?

    Peterson claims that the LEDs don't lose intensity based on their knowledge of the chemistry of the LEDs they've specified (see here*), the type of thermal management they've employed, as well as through rigorous testing. This is Peterson, not PIAA.

    *The chart shows that blue and white LEDs (white ones being essentially a blue LED with an added phosphor) have a less-steep intensity drop-off from increased temperatures than red ones.
    Last edited by Alaric Darconville; 02-04-2018 at 06:09 PM.

  19. #19

    Default Re: Koito's new red phosphor

    Quote Originally Posted by Alaric Darconville View Post
    What does "so the lumens drop until the temperature settles at a given level" even mean?
    In the real world? It means nothing. It's word-salad.

  20. #20
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    Default Re: Koito's new red phosphor

    It's interesting, but not earth shattering. There is far more interest in narrow band quantum phosphors for high efficiency than High CRI since we can already do pretty well in that area . Realistically, beyond 2700/3000K, and "sunlight" no one has ever seen a so-called 100cri source.

    GE, Soraa, Nichia, all have violet pumped LEDs with higher CRI, but always lower efficiency. That is no different from the vast majority of installed fluorescent which is mainly 80CRI since high CRI take an efficiency loss, just like LEDs from Stokes losses and no QE>1 phosphors seem to be on the horizon.

    I really don't see any benefit to vehicle headlights. Any CRI > 80 is pretty much meaningless.

  21. #21
    Moderator Alaric Darconville's Avatar
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    Default Re: Koito's new red phosphor

    Quote Originally Posted by ssanasisredna View Post
    I really don't see any benefit to vehicle headlights. Any CRI > 80 is pretty much meaningless.
    It's not CRI I'm after, it's a sensible CCT. Something in the 3000-to-3500 K range.

  22. #22

    Default Re: Koito's new red phosphor

    Quote Originally Posted by ssanasisredna View Post
    I really don't see any benefit to vehicle headlights. Any CRI > 80 is pretty much meaningless.
    Talk to off-roaders and you'll get an earful (or two) about inadequate CRI from LEDs and HIDs making it difficult to drive safely on the trail because it's impossible to tell apart the shades and tints of grey, brown, beige, and green that can mean the difference between solid ground and deep puddle, clear trail and boulder, etc.

  23. #23
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    Default Re: Koito's new red phosphor

    Quote Originally Posted by -Virgil- View Post
    Talk to off-roaders and you'll get an earful (or two) about inadequate CRI from LEDs and HIDs making it difficult to drive safely on the trail because it's impossible to tell apart the shades and tints of grey, brown, beige, and green that can mean the difference between solid ground and deep puddle, clear trail and boulder, etc.
    We both know how much the average off-roader knows about CRI or lighting .... and is likely whining about not being able to tells "shades" because they are using 5000-6000K HIDs or LEDs with <80CRI and have no clue what a good >80 CRI LED in the <= 4000K range would even look like in an off-road situation, let alone something in the 3500K tuned for gamut area and not CRI. It's sort of crazy as Lumileds developed the "neutral white" CCT range that flashlight people now swear by for automotive applications to give more contrast in the real world .... but marketing wins over performance as long as you meet regulations.

  24. #24
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    Default Re: Koito's new red phosphor

    Quote Originally Posted by Alaric Darconville View Post
    It's not CRI I'm after, it's a sensible CCT. Something in the 3000-to-3500 K range.
    I would be happy just to get back to a sensible 4000 at this point.

  25. #25

    Default Re: Koito's new red phosphor

    Quote Originally Posted by ssanasisredna View Post
    likely whining about not being able to tells "shades" because they are using 5000-6000K HIDs or LEDs with <80CRI and have no clue what a good >80 CRI LED in the <= 4000K range would even look like in an off-road situation, let alone something in the 3500K
    Right...but it's not like they have a choice, it's because those 5000K-6000K, heavy-on-the-blue LEDs are what's available; the kinds of LEDs that would give better light quality are not (so far) used in lights for vehicles. To try and move this thread back to topic, that's why the Koito and Seoul Semiconductor announcements are promising. They suggest that the quality of light from LED vehicle lamps might get some more attention paid to it, which is overdue.

    It's sort of crazy as Lumileds developed the "neutral white" CCT range that flashlight people now swear by for automotive applications to give more contrast in the real world .... but marketing wins over performance as long as you meet regulations.
    Unfortunately true. I'm hoping some of the research ongoing right now into what's being called "human-centric lighting" will wind up providing some solid basis for better-quality light from LED headlamps on the demand side, while things like this Koito red phosphor and the Seoul Semiconductor SunLike purple-chip LEDs help out on the supply side.

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