Polychromatic Pixels

A 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

This 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://web.archive.org/web/20240302185148/https://www.zephr...

Hm, 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).

This appears to be done by varying current, from a slide in this 'webinar': 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

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.

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. 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.

Would 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/S092547739... https://onlinelibrary.wiley.com/doi/10.1111/j.1755-148X.2010...

I 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.

I 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.

> 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.

OLED 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.

The 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.

These 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.

Does this need very accurate DAC to cover the entire color spectrum? Maybe even fine-tuning on each pixel?

Are they able to adjust the color and brightness simultaneously? Or would brightness be controlled with PWM?

Porotech propose the same concept

https://www.porotech.com/technology/dpt/

Demo video

https://youtu.be/758Xzi_nK8w

Incredible 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.

I imagine color consistency will be such a pain here.

This sounds awesome for future VR gear, when you need small displays with more pixels that is currently possible.

4K virtual monitors, here we come!

Did anybody notice just how fast their website loads? I didn’t even look at the content yet and I’m already impressed.

This 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.

Any idea if there is a plan to produce discrete LEDs that are tunable?

I wonder if these would improve VR/AR headset displays.

I hope this will go into AVP3

My 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.