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Thread: Nichia introduces violet pump based ultra high cri mid power leds

  1. #1
    Flashaholic anuragwap's Avatar
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    Default Nichia introduces violet pump based ultra high cri mid power leds

    They finally made the switch! (http://www.nichia.co.jp/en/product/l...optisolis.html) Maybe Prof. Nakamura at Soraa was right to say that violet pump leds will eventually take over blue pump ones. Their new series is named Optisolis. From the datasheet, it has a peak at 420nm, does not suffer from cyan gap, comes in neutral and warm, has respectable 120+lm/W efficacy. I guess exciting times are ahead for high CRI snobs, very soon we may see high power Nichia leds that have better color rendering than R9080 219Bs and yet higher efficacy than Yuji leds.

  2. #2

    Default Re: Nichia introduces violet pump based ultra high cri mid power leds

    GOOD TINT!

  3. #3

    Default Re: Nichia introduces violet pump based ultra high cri mid power leds

    Neat, wonder how long it will take to get to 219B specs though as 5mm LEDs beat these for the moment.

  4. #4

    Default Re: Nichia introduces violet pump based ultra high cri mid power leds

    Bah! Look at that measly R9 score of 94!

    I'm glad to see Nichia taking a venture in this direction.

    Keep expectations reasonable though. Blue-pumped LED's already can achieve excellent performance in the red range, which is where white LED's have traditionally been most lacking. The violet-pumped LED's main place to offer an advantage is in the small range between the ~450nm peak of blue LED's, and the roughly 400nm peak of the violet LED's they're using.

    I think the subjects where these blue-violet shades are critical are less common than the red tones that are needed to make the human complexion look healthy, see the undertones of woodwork, etc. But they're not absent, of course - artwork, paints, and flowers are subjects that should benefit from better blue-violet rendering.

    Also, the way the color scores are computed, I expect the newer, but less commonly used CQS scores to show larger improvements for violet-pumped LED's than CRI scores.

  5. #5

    Default Re: Nichia introduces violet pump based ultra high cri mid power leds

    Quote Originally Posted by iamlucky13 View Post
    Bah! Look at that measly R9 score of 94!

    I'm glad to see Nichia taking a venture in this direction.

    Keep expectations reasonable though. Blue-pumped LED's already can achieve excellent performance in the red range, which is where white LED's have traditionally been most lacking. The violet-pumped LED's main place to offer an advantage is in the small range between the ~450nm peak of blue LED's, and the roughly 400nm peak of the violet LED's they're using.

    I think the subjects where these blue-violet shades are critical are less common than the red tones that are needed to make the human complexion look healthy, see the undertones of woodwork, etc. But they're not absent, of course - artwork, paints, and flowers are subjects that should benefit from better blue-violet rendering.

    Also, the way the color scores are computed, I expect the newer, but less commonly used CQS scores to show larger improvements for violet-pumped LED's than CRI scores.
    Why do you expect CQS to show a larger improvement? Compared to traditional sources, good LEDs can exceed traditional lighting scores. I would expect only marginal benefits for violent pumped emitters.

    I don't see this ever displacing blue pumped, 455 versus 400nm is always going to have an efficiency advantage due to Stokes losses in the phosphor conversion. Perhaps in the home it will achieve high penetration, at least in N.A. and Europe where low CCT is popular in the home. We have the ability to have very high CRI fluorescent but the vast vast majority isn't due to lower efficiency.

  6. #6

    Default Re: Nichia introduces violet pump based ultra high cri mid power leds

    Quote Originally Posted by ssanasisredna View Post
    Why do you expect CQS to show a larger improvement? Compared to traditional sources, good LEDs can exceed traditional lighting scores. I would expect only marginal benefits for violent pumped emitters.

    I don't see this ever displacing blue pumped, 455 versus 400nm is always going to have an efficiency advantage due to Stokes losses in the phosphor conversion. Perhaps in the home it will achieve high penetration, at least in N.A. and Europe where low CCT is popular in the home. We have the ability to have very high CRI fluorescent but the vast vast majority isn't due to lower efficiency.
    Due to the way CQS is measuered vs. CRI - it is more critical of the blue and violet range, as I understand it. I should actually go check Maukka's data to confirm this. I'd expect his measurements will generally show slightly lower CQS numbers than CRI.

    I agree about the blue pumped advantage.

  7. #7

    Default Re: Nichia introduces violet pump based ultra high cri mid power leds

    Quote Originally Posted by iamlucky13 View Post
    Bah! Look at that measly R9 score of 94!

    Keep expectations reasonable though. Blue-pumped LED's already can achieve excellent performance in the red range, which is where white LED's have traditionally been most lacking.
    Just my opinion on this, I think in general the violet-emitter white LEDs put out by major brand name companies are going to have only moderately high R9 red values, when it comes to CRI. The reason is that violet-emitter already achieves exceptionally high R6 and R12 (blue) values, therefore when it comes to R9 (deep saturated red) it's not seen as so absolutely critical to achieving overall high CRI values. By making sacrifices in the R9 value it's possible to achieve substantial increase in overall luminous efficiency, more than enough to offset the slight decrease in efficiency from using a violet-emitter.


    Quote Originally Posted by iamlucky13 View Post
    I think the subjects where these blue-violet shades are critical are less common than the red tones that are needed to make the human complexion look healthy, see the undertones of woodwork, etc.

    Actually human skin tones can look just fine with only moderately high R9 values, 80-90. Skin tones actually have a more orange-red hue, so as long as the light strongly illuminates orange-red colors, it doesn't matter so much whether the red lacks deep saturation. We're talking about typically 92-94 CRI. The only downside is that deep ruby colors may appear somewhat coral colored. They're brightly illuminated and lively but just not the most perfect deep red color hue saturation. This isn't going to be the most flattering to crimson red colors.

    You are right, in most applications there is going to be no need for violet-emitter white LEDs.


    Quote Originally Posted by iamlucky13 View Post
    The violet-pumped LED's main place to offer an advantage is in the small range between the ~450nm peak of blue LED's, and the roughly 400nm peak of the violet LED's they're using.
    You know, it is theoretically possible to achieve a more even distribution of blue wavelengths without using the violet-emitter approach. (Like say with better blue-green phosphors to make sure there's less of a dip in the 470-500nm territory, or designing in separate emitters to fill in the gap) If violet emitter LED lighting started popping up everywhere I'm thinking all that violet light might not be the best for us. Light starts getting more reactive and can induce more chemical changes the shorter the wavelength.

    I've played around with some theoretical CRI software and what I've found is that if you want to maintain excellent R12 values with a dominant blue spike, it's important that a gap be maintained between the 450nm and around 480nm or so (no precise values here) but it doesn't matter much after that. What I mean is that adding in a 500nm (cyan-green) spike is barely going to have any effect on the R12. If, on the other hand, you add even a small 470nm spike, you better add some shorter wavelengths on the other side of the 450nm (normal blue LED spike) to balance it out, otherwise the R12 is going to get thrown off. Even adding a small amount of 430nm will have a big positive effect on the R12. What I mean is that if you're not using the right blue wavelengths, even adding in a very small amount of the ones you don't have will have very substantial effects.

    I'm imagining that in commercial retail applications they might choose to go 420nm instead of 430nm because of the significantly better effect on optical brighteners, even though it will have no difference on the R12. If we're talking about trying to minimize the shorter wavelengths, there's a bunch of trade-offs. (But nothing specifically wrong with violet LEDs if you're okay having metal discharge lamps everywhere)


    Quote Originally Posted by ssanasisredna View Post
    I don't see this ever displacing blue pumped, 455 versus 400nm is always going to have an efficiency advantage due to Stokes losses in the phosphor conversion.
    You know, it is potentially possible for a hybrid approach. Where a blue emitter would activate red and green phosphors while the violet emitter would activate just blue. I'm not sure how that would be combined into one LED dye though, might cause some manufacturing complications.


    Quote Originally Posted by anuragwap View Post
    Maybe Prof. Nakamura at Soraa was right to say that violet pump leds will eventually take over blue pump ones.
    Prof. Nakamura is working really hard trying to develop violet emitters that exceed the efficiency of blue emitters, so that his new violet-emitter white LEDs will be able to slightly exceed the efficiency of current generation blue-emitter white LEDs and overcome the inherent lower efficiency of converting violet into white light. Of course, any advances in the efficiency of violet LEDs would very likely carry over into blue LEDs also (since they are both based on the same GaN chemistry), so ultimately blue-emitter white LEDs will still be the most efficient in the end.

    Last edited by JoakimFlorence; 02-12-2018 at 10:10 PM.

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