13 ms·
Polychromatic Pixels
- Teknomancer 2y agoOLED tech has been very transformative for lots of my old gear (synthesizers and samplers mostly) that originally came with backlit LCD displays. But the OLEDs are offered in static colors, usually blue or amber. Sometimes white red or green It would be very cool to have a display with adjustable color.
- 01100011 2y agoAny idea if there is a plan to produce discrete LEDs that are tunable?
- dmitrygr 2y agoThese still produce a single [adjustable] wavelength, which means some colors that are displayable on displays of today are not representable using just one of these, and multiples will be required.
- Scene_Cast2 2y agoI suppose anything besides the edge of the CIE horseshoe will need multiples.
- yig 2y agoTwo adjustable wavelength emitters should be sufficient, right? So the picking-and-placing problem gets easier by factor of 3:2 rather than 3:1.
- modeless 2y agoI bet you might run into some interesting problems trying to represent white with two wavelengths. For example, colorblind people (7% of the population) might not perceive your white as white. And I wonder if there is more widespread variation in human eye responses to single wavelengths between primary colors that is not classified as colorblindness but could affect the perception of color balance in a 2-wavelength display.
- mark-r 2y agoThe whole point of this technology is that you don't need picking-and-placing anymore, it's all built on the same wafer.
- mistercow 2y agoIf the refresh rate is high enough, a single LED could flip between multiple wavelengths to dither to non spectral colors.
- layer8 2y agoHigher refresh/modulation rates imply higher power consumption. It’s already a trade-off in current display tech for mobile.
- mistercow 2y agoSure, but that’s assuming you need a higher rate than is already used for brightness. That’s a question I think can only be determined experimentally by putting real human eyes on it, although I think you could do the experiment with traditional RGB LEDs. But the other question is whether the wavelength tuning can be changed at the same rate as intensity.
- MT4K 2y agoOr if pixel density is high enough, adjacent pixels could display the colors to combine with no flickering. Unlike regular RGB subpixels, this would only be needed for areas where the color cannot be displayed by an individual pixel alone.
- mistercow 2y agoYeah, and both techniques can be combined, which common with LCD screens, although it does sometimes lead to visible moving patterns when viewed close up. There’s more flexibility with tunable wavelengths, though, since there will often be multiple solutions for what colors and intensities can be combined to create a particular photoreceptor response. By cycling through different solutions, I wonder if you could disrupt the brain’s ability to spot any patterns, so that it’s just a very faint noise that you mostly filter out.
- layer8 2y agoYes, it’d be two subpixels instead of the current three. It’s not clear that that’s worth the added complexity of having to control each subpixel across two dimensions (brightness and wavelength) instead of just one (brightness).
- Retr0id 2y agoCan you produce "white" with just two wavelengths?
- deleted 2y ago[deleted]
- layer8 2y agoYes, mix two complementary colors like orange and cyan. You just need two wavelengths that hit all three cone types [0] in the right ratio. There’s the possibility that it’s subject to more variation across individuals though, as not everyone has exactly the same sensitivity curves. [0] https://upload.wikimedia.org/wikipedia/commons/f/f1/1416_Color_Sensitivity.svg https://upload.wikimedia.org/wikipedia/commons/f/f1/1416_Col...
- exmadscientist 2y agoHuman vision in the yellow (~590nm) region is known to be extremely sensitive to particular wavelengths. Observe how quickly things go from green through yellow to amber/orange! So this is probably a nonstarter.
- mark-r 2y agoEvery single white LED bulb you buy for your light fixtures is a mix of blue LED and yellow phosphor, so in practice it's no problem at all. Although I do concede that the yellow is probably not monochromatic.
- exmadscientist 2y ago
- Retr0id 2y agoThis vaguely reminds me of "CCSTN" (Color Coded Super Twisted Nematic) LCD displays, which were used in a few Casio calculators to produce basic colour output without the usual RGB colour filter approach. https://www.youtube.com/watch?v=quB60FmzHKQ https://www.youtube.com/watch?v=quB60FmzHKQ https://web.archive.org/web/20240302185148/https://www.zephray.me/post/cfx_9850_review/ https://web.archive.org/web/20240302185148/https://www.zephr...
- accrual 2y agoI had a feeling the YouTube link would be Posy and was delighted when it was. His videos on display technologies are top notch.
- nayuki 2y agoI noticed an unusual color LCD technology on the Pokémon Pikachu 2 GS too: https://electronics.stackexchange.com/questions/201827/how-does-color-lcd-work-on-the-pok%c3%a9mon-pikachu-2-gs https://electronics.stackexchange.com/questions/201827/how-d... , https://bulbapedia.bulbagarden.net/wiki/Pok%C3%A9mon_Pikachu_2_GS https://bulbapedia.bulbagarden.net/wiki/Pok%C3%A9mon_Pikachu...
- chefandy 2y agoFor some reason I find those displays' shades of orange and green to be SUPER appealing. The blue is nice enough.
- itishappy 2y agoThis is super cool! I can certainly see these being useful in informational displays, such as rendering colored terminal output. The lack of subpixels should make for crisp text and bright colors. I don't see this taking over the general purpose display industry, however, as it looks like the current design is incapable of making white.
- hidelooktropic 2y agoIncredible accomplishment, but the question remains what this will look like at the scale of a display on any given consumer device. Of course, it's only just now been announced, but I'd love to see what a larger scale graphic looks like with a larger array of these to understand if perceived quality is equal or better, if brightness distribution across the spectrum is consistently achieved, how pixels behave with high frame rates and how resilient they are to potential burn-in.
- p1esk 2y agoI hope this will go into AVP3
- joshmarinacci 2y agoAlien Vs Predator 3?
- p1esk 2y agoApple Vision Pro 3
- maxrumpf 2y agoI imagine color consistency will be such a pain here.
- Retr0id 2y agoI'd hope that per-pixel calibration would solve that, but I wonder how much that calibration would drift over time.
- mensetmanusman 2y agoWhatever the drift would be, inorganics would drift less than organic materials.
- k7sune 2y agoDoes this need very accurate DAC to cover the entire color spectrum? Maybe even fine-tuning on each pixel?
- Joel_Mckay 2y agoLED are somewhat temperature sensitive devices, and getting repeatable high-granularity bit-depth may prove a difficult problem in itself. There are ways to compensate for perceptual drift like modern LCD drivers, but unless the technology addresses the same burn-in issues with OLED it won't matter how great it looks. You may want to look at how DMD drivers handled the color-wheel shutter timing to increase perceptual color quality. There are always a few tricks people can try to improve the look at the cost of lower frame rates. =)
- jjmarr 2y agoMy ultimate hope is that this will allow us to store and display color data as Fourier series. Right now we only represent colour as combinations of red, green, and blue, when a colour signal itself is really a combination of multiple "spectral" (pure) colour waves, which can be anything in the rainbow. Individually controllable microLEDs would change this entirely. We could visualize any color at will by combining them. It's depressing that nowadays we have this technology yet video compression means I haven't seen a smooth gradient in a movie or TV show in years.
- ginko 2y agoWith two wavelength-tunable LEDs you should be able to cover the entire CIE colorspace. That's because the points on outer edge of CIE are pure wavelengths and you can get to any point inside by interpolating between two of them.
- bobmcnamara 2y agoHow do you make white?
- meindnoch 2y agoE.g. mix 480nm cyan and 590nm orange.
- llama_drama 2y agoWould this be practical? Or would it be similar to how printers have separate black ink, which is theoretically unnecessary?
- layer8 2y agoBy mixing two complementary colors.
- meindnoch 2y agoWhat would be the purpose of this? The human eye can't distinguish light spectra producing identical tristimulus values. Thus for display purposes [1], color can be perfectly represented by 3 scalars. [1] lighting is where the exact spectrum matters, c.f. color rendering index
- nfriedly 2y ago> 6,800 pixel-per-inch display (around 1.1 cm by 0.55 cm, and around 3K by 1.5K pixels) That sounds like it's getting close to being a really good screen for a VR headset.
- k__ 2y agoNice, that's double of what the Vision Pro has.
- Retr0id 2y agoHm, thinking about this further, this would need dithering to work properly (which probably works fine, but the perceived quality difference would mean pixel density comparisons aren't apples-to-apples) Presumably, you get to control hue and brightness per-pixel. But that only gives you access to a thin slice of the sRGB gamut (i.e. the parts of HSL where saturation is maxed out), but dithering can solve that. Coming up with ideal dithering algorithms could be non-trivial (e.g. maybe you'd want temporal stability).
- refulgentis 2y agoI'm not sure why saturation couldn't be controlled. I probably missed something in the article, though I do see ex. desaturated yellow in the photographs so I'm not sure this is accurate. If you can't control saturation, I'm not sure dithering won't help, I don't see how you'd approximate a less saturated color from a more saturated color. HSL is extremely misleading, it's a crude approximation for 1970s computing constraints. An analogy I've used previously is think of there being a "pure" pigment, where saturation is at peak, mixing in dark/light (changing the lightness) changes the purity of the pigment, causing it to lose saturation.
- Retr0id 2y agoSaturation can't be controlled on a per-pixel basis because, per the article, they're tuned to a specific wavelength at any given time. You're right though, there appear to be yellows on display. Maybe they're doing temporal dithering. Edit: Oh wait, yellow doesn't need dithering in any case. Yellow can be represented as a single wavelength. Magenta on the other hand, would (and there does seem to be a lack of magenta on display)
- refulgentis 2y agoHonestly might just be the limits of photography, there's so much contrast between the ~97 L* brightness of pure yellow and black that the sensor might not be able to capture the "actual" range. I've been called a color scientist in marketing, but sadly never grokked the wavelength view of color. It sounds off to me, that's a *huge* limitation to not mention. But then again, if they had something a year ago, its unlikely ex. Apple folds its microLED division they've been investing in for a decade. Either A) it sucks or B) it doesn't scale in manufacturing or C) no ones noticed yet. (A) seems likely given their central claim is (B) is, at the least, much improved.
- hobscoop 2y agoAre they able to adjust the color and brightness simultaneously? Or would brightness be controlled with PWM?
- kurthr 2y agoBrightness is PWM controlled, but likely at the micro - millisecond level. The required brightness range is about 100k:1. Black levels would be determined more by reflectivity of the display than illumination.
- nomdep 2y agoThis sounds awesome for future VR gear, when you need small displays with more pixels that is currently possible. 4K virtual monitors, here we come!
- Joel_Mckay 2y agoThey already have these, but people need to modify the GPU designs before it is really relevant. The current AI hype cycle has frozen development in this area for now... so a super fast 1990's graphics pipeline is what people will iterate on for awhile. Nvidia is both a blessing and a curse in many ways for standardization... =3
- FriedPickles 2y agoI didn't realize we even had a discrete LED tunable across the visible spectrum, let alone a Micro-LED array of them. Anybody know where I can buy one? I want to build a hyperspectral imager.
- jessriedel 2y agoDo you mean hyperspectral imager (i.e., camera), or a hyperspectral display?
- FriedPickles 2y agoAn imager/camera: by illuminating a scene (or light box) solely with the tunable LED, sweeping it across the spectrum, and capturing it with an achromatic camera.
- jessriedel 2y agoAhh, that makes sense. Thanks! Btw, is that still reasonably effective if the scene has ambient illumination, but (in addition to shining each wavelength at it) you take a monochrome photo in only the ambient light and you subtract that out from all your other images?
- FriedPickles 2y agoSure that would work. The higher the ratio of controlled/ambient light, and the slower you can do the sweep, the better for SNR of the hyperspectral image.
- lsaferite 2y ago> achromatic camera Is that the same as a panchromatic camera? Edit: Asking because I have a 410x410px hyperspectral imager that has an aligned 1886x1886px panchromatic imager that is use to perform pan-sharpening of the HSI data bringing it up to 1886x1886. I'd never heard of a panchromatic camera before I got involved in this business and I've never heard of an achromatic camera either. All I seem to find is achromatic lenses.
- mxfh 2y agoWould be fun if displays come full circle with variable addressable geometry/ glowing goo too. Not quite vector display, but some thing organic than can be adressed with some stimulators like reaction-diffusion or gaussian, FFT, laplacians, gabor filters, Turig patterns, etc. Get fancy patterns with lowest amount of data. https://www.sciencedirect.com/science/article/pii/S0925477399002117 https://www.sciencedirect.com/science/article/pii/S092547739... https://onlinelibrary.wiley.com/doi/10.1111/j.1755-148X.2010.00814.x https://onlinelibrary.wiley.com/doi/10.1111/j.1755-148X.2010...
- GrantMoyer 2y agoA single wavelength can't reproduce all visible colors. These pixels are variable wavelength, but can only produce one at a time, so you'd still need at least 2 of these pixels to reproduce any visible color. The fundamental problem is that color space is 2D[1] (color + brightness is 3D, hence 3 subpixel on traditional displays), but monochromatic light has only 1 dimension to vary for color. [1]: https://en.wikipedia.org/wiki/Chromaticity https://en.wikipedia.org/wiki/Chromaticity
- FriedPickles 2y agoIt can produce all the colors of the rainbow. But no magenta. Perhaps they can quickly pulse the LED enough between multiple wavelengths.
- PaulHoule 2y agoSee also https://en.wikipedia.org/wiki/Spectral_color https://en.wikipedia.org/wiki/Spectral_color This reminds me of the observation I had in high school that I could immerse LEDs in liquid nitrogen and run them at higher than usual voltage and watch the color change. I got a PhD in condensed matter physics later on but never got a really good understanding of the phenomenon but I think it has something to do with https://www.digikey.com/en/articles/identifying-the-causes-of-led-efficiency-droop https://www.digikey.com/en/articles/identifying-the-causes-o... Here is a video of people doing it https://www.youtube.com/watch?v=5PquJdIK_z8 https://www.youtube.com/watch?v=5PquJdIK_z8
- duskwuff 2y ago> I got a PhD in condensed matter physics later on but never got a really good understanding of the phenomenon but I think it has something to do with The color of most* LEDs is controlled by the band gap of the semiconductor they're using. Reducing the temperature of the material widens the band gap, so the forward voltage of the diode increases and the wavelength of the emitted light gets shorter https://www.sciencedirect.com/science/article/abs/pii/0031891467900626 https://www.sciencedirect.com/science/article/abs/pii/003189... *: With the exception of phosphor-converted LEDs, which are uncommon.
- modeless 2y agoI understand that one of the big issues with microLED is huge brightness variation between pixels. Due to some kind of uncontrollable (so far) variations in the manufacturing process, some pixels output 1/10 the light (or less) as others. Ultimately the brightness of the whole display is constrained by the least bright pixels because the rest have to be dimmed to match. Judging by their pictures they have not solved this problem.
- mensetmanusman 2y agoIt is solvable with enough capital investment though, question is how much will it cost to solve.
- modeless 2y agoIs it? I feel like there has already been a lot of capital investment by the various organizations working on microLED.
- cubefox 2y ago> I understand that one of the big issues with microLED is huge brightness variation between pixels. Due to some kind of uncontrollable (so far) variations in the manufacturing process, some pixels output 1/10 the light (or less) as others. I instead understand that this is false. Available MicroLED screens (TVs) are in fact brighter than normal screens. The issue with MicroLED is instead that they are extremely expensive to produce, as the article points out, due to the required mass transfer. Polychromatic LEDs would simplify this process greatly.
- georgeburdell 2y agoThe promotional document focuses on wavelength tunability but I imagine brightness at any one wavelength suffers because to emit at one wavelength requires an electron to lose the amount of energy in that photon by transitioning from a high to low energy state. Maximum brightness then corresponds to how many of these transitions are possible in a given amount of time. Some states are not accessible at a given time (voltage can tune which states are available) but my understanding is the number of states is fixed without rearranging the atoms in the material.
- KennyBlanken 2y agoThis appears to be done by varying current, from a slide in this 'webinar': https://youtu.be/MI5EJk8cPwQ?t=238 https://youtu.be/MI5EJk8cPwQ?t=238 That's not hugely surprising given that (I believe) LEDs have always shifted spectrum-wise a bit with drive current (well, mostly junction temperature, which can be a function of drive current.) I guess that means they're strictly on/off devices, which seems furthered by this video from someone stopping by their booth: https://youtu.be/f0c10q2S_PQ?t=107 https://youtu.be/f0c10q2S_PQ?t=107 You can clearly see some pretty shit dithering, so I guess they haven't figured out how to do PWM based brightness (or worse, PWM isn't possible at all?) I guess that explains the odd fixation on pixel density that is easily 10x what your average high-dpi cell phone display has (if you consider each color to be its own pixel, ie ~250dpi x 3) It seems like the challenge will be finding applications for something with no brightness control etc. Without that, it's useless even for a HUD display type widget. In the meantime, if they made 5050-sized LEDs, they would probably print money...which would certainly be a good way to further development on developing brightness control.
- exmadscientist 2y ago> if they made 5050-sized LEDs I doubt they can. Probably the process only works (or yields) small pieces, otherwise they'd be doing exactly what you suggest. I also notice that their blues look terrible in the provided images. Which will be a problem. I don't think they get much past 490nm or so? That would also explain why they don't talk at all about phosphors, which seem like a natural complement to this tech... I don't think they can actually pump them. Which is disappointing :(
- knotimpressed 2y agoI think a lot of these comments are missing the point-even if you have to reduce their reported density numbers by half, they made a display with dimensions of "around 1.1 cm by 0.55 cm, and around 3K by 1.5K pixels", which is insane! All without having to dice and mass-transfer wafer pieces, since every pixel is the same. A lot of the article is focused on how this matters for the production side of things, since combining even 10 um wafer pieces from 3 different wafers is exceedingly time consuming, which I think is the more important part. Sure, the fact that each emitter can be tuned to "any colour" might be misleading, but even if you use rapid dithering like plasma displays did, and pin each emitter to one wavelength, you suddenly have a valid path to manufacturing insanely high density microLED displays! Hopefully this becomes viable soon, so I can buy a nice vivid and high contrast display without worrying about burn in.
- wmertens 2y agoI'm really curious about the reproducibility. The color is decided by the bandgap and the bandgap is tunable by voltage, but how temperature dependent is it, and how much does production variability impact it? I image these displays could have color sensors attached to self-calibrate. Or the variability is low and all you need is very precise voltages. I think the first versions will be RGB displays with fixed colors, just no longer needing mass transfer. You could use tens of subpixels per pixel, reducing all worries about color resolution. Make these into e.g. 1x1cm mini displays and mass transfer those into any desired display size.
- speakspokespok 2y agoDid anybody notice just how fast their website loads? I didn’t even look at the content yet and I’m already impressed.
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- amazon88 2y ago[dead]
- bluehat974 2y agoPorotech propose the same concept https://www.porotech.com/technology/dpt/ https://www.porotech.com/technology/dpt/ Demo video https://youtu.be/758Xzi_nK8w https://youtu.be/758Xzi_nK8w
- hosh 2y agoI wonder if these would improve VR/AR headset displays.
- whjkh 2y ago[flagged]