MicroLEDs Moving from Lab to Fab | Hacker News Reader

MicroLEDs Moving from Lab to Fab

semiengineering.com

>Haynes noted, however, that the timeline for commercialization of large area displays on TFT panels “will depend on how quickly the industry develops mass transfer technologies that can deliver high accuracy and exceptional reliability.” Indeed, Apple’s latest iPad, which uses white miniLEDs for backlighting, requires the accurate placement of 10,000 emitters, which sounds challenging enough. Positioning 25 million red, green, and blue subpixels on a 78-inch TFT panels for a 4K TV, with a tolerance of only 10 non-functioning pixels, will require an exceedingly robust, highly accurate transfer method.

>Different Paths to RGB...... Basically uLED Backlight with QD

And the rest. As much as I love and want uLED. None of these are new, and the problem has been roughly the same from day 1 in 2016 when all the media were jumping on uLED. Even if they could solve all of that they still dont have a roadmap of cost reduction that could match OLED.

On the other hand OLED cost has been dropping quicker than expected. It is another one of those thing like Solar panel where all industry analysis and projection were wrong. We also have a solid roadmap to improve colour accuracy, burn rate, efficiency etc. Along with other "potential" OLED adjacent technology like QNEDs where it is 80-90% of uLED but could be used on existing OLED manufacturing.

Again as much as I love to see uLED, objectively speaking I just dont see how it could compete. And it is one of those moment where better is the enemy of the best.

I am old enough to remember when OLED was in the same boat. Yield was low, expected life was short and RGB was far off.

I was extremely excited when I got my hands on a 2 line character single color OLED display many years ago. That a phone would ever have an OLED color display was a far off fantasy.

I am sure we will see uLED at some point, it just takes time and a lot of research.

Yes, I remember when OLED:s were far off future technology for mass consumption. I think the first OLED display I saw was a tiny Sony PAL TV that probably cost an arm and leg back then. The analyst consensus back then was that OLEDs are too hard/expensive/etc for generic consumers.

> I am old enough to remember...

It was like 8 years ago!

No, it was much longer ago, especially for pre-RGB applications. OLEDs came about in the late 80's, and mono displays started showing up in the 90s (I think one of my early flip phones had an OLED exterior display). RGB units were demonstrated around 2000 and commercialized in limited uses in the very early 2000's.

I'm old enough to remember almost nothing...

I remember standing the lobby at work watching the company's stock performance displayed on a Sony plasma TV and thinking "that TV cost $12,000 and that's what they're doing with it."

Now that seems so long ago...

>Again as much as I love to see uLED, objectively speaking I just dont see how it could compete. And it is one of those moment where better is the enemy of the best.

Burn in is a very serious issue with OLED as well as overall lifespan due to the organic nature of the diodes. uLED is probably a better technology for a variety of applications that have to factor those issues in.

It would be quite awful if the supposed durability of miniLEDs would turn out to be an environmental disaster for chemical leaching (due to the number of LEDs) and microplastics.

The amount of plastics in a display panel is much less than the amount of plastic bottles most people go through in a week or less. Yes, every little bit contributes, but you need to focus efforts on the impactful sources first .

> And the rest. As much as I love and want uLED. None of these are new, and the problem has been roughly the same from day 1 in 2016 when all the media were jumping on uLED. Even if they could solve all of that they still dont have a roadmap of cost reduction that could match OLED.

Not even 2016. Samsung had uLED type display RnD going in their Samsung Research Institute since 2006.

Just as with OLED, despite all of the crazy tech investor money, it's very clear who will reach the finish line first.

Samsung probably already has a commercialisable solution, but is just keeping it in the sleeve, waiting for an appropriate moment, like OLED profits shrinking, or somebody else getting close to microled commercialisation.

OLED technology has two significant problems that will not be solved anytime soon:

1. Blue OLEDS do not last, they degrade much faster than the other colors.

2. Burnout.

This is intrinsic to the technology. LED tech has not those problems. uLEDs technology already works very well, much better than OLEDs, it is just too expensive. There is no need for inventing new technology.

Also, when talking about LEDs we must talk about the inverse technology: Solar panels. Improvements and investment in solar panel technologies transfer to LEDs fast because it is the inverse: Any LED or light emitting diode does generate electricity when light.

OLED promising advantage for the future is the possibility of being printed extremely cheap and superfast on plastic substrates, specially for solar panels, at cents/square meter. But right now showstoppers exist for that tech.

Are they really not solved? Because there are a lot of high end devices with OLED displays for a while now, eg Samsung Galaxy, iPhone X series and Huawei, and their displays haven't degraded over say 5 years from what I can tell.

All of them have burnin it's inevitable.

Just like how all SSDs will fail after enough writes. A problem that I will never stress over.

I have had many oled devices for many years and I have never once seen noticeable burn in like I have never had an ssd die.

I’m not denying it exists. But the scale of the problem and the time it takes to occur make it a non issue for most use cases.

OLED burn in is the main reason I haven't bought one to use as a monitor. The taskbar is probably gonna burn in as it just doesn't change much.

OLED burn-in is likely less of a problem with phones because the useful life of most phones is only a few years. Laptops and monitors are a different story as they typically last for 5-10+ years.

>eg Samsung Galaxy, iPhone X series and Huawei, and their displays haven't degraded over say 5 years from what I can tell.

Of those I've only had the iPhone X and now iPhone 12 (and will note that the iPhone X only launched in November 2017, just 3.5 years ago, and I'll never know how it lasts to 5 years anyway because my upgrade cycle remains faster than 5 years for now). But on the iPhone side of things at last, there are a host of mitigation measures both inherent to iOS and new since the LCD. The iPhone X series for example is quite aggressive by default about powering off the display. They do a decent job of it thanks to the Face ID sensors letting them have some form of attention monitoring coupled with fairly transparent quick wakeup/unlock, but it's still noticeable even now. iOS in general also has very, very little fixed chrome. Not nothing, but not much. Most of the display, as with TVs, is constantly shifting content. Even browsing the web on a tiny screen involves lots of scrolling and movement.

None of this stuff makes much if any sense in typical desktop/notebook computing. There are a lot more static UI elements present all the time, and that's a good thing with high precision mouse pointers and large screens. We count on screens to passively display information constantly, even if we're not actively interacting with them right that second. We also tend to use computers for a much longer time. I don't have a 4 year old phone. I do have a 10 year old system still in a final few months of service, and a number of 6-7 year old systems that may last longer. There are LCD displays at work even older than that still doing well.

Maybe OLED will evolve far enough to handle that acceptably as well, but I don't think you can extrapolate from phones. It's not like the industry hasn't been able to make big high resolution OLED displays for a while now. The curious dearth of them in notebooks/AIOs/standalone PC monitors points at something.

My iPhone X has burn-in from Google maps navigation. The killer combination seems to have been many hours on a mount in the sunlight behind my windshield, running a moderately intensive app (generating a fair amount of heat) that always has a few static elements (the car arrow, a few circular buttons) and keeping the screen on 100% of the time.

It's not particularly noticeable unless you're looking at an all-white web page or email or something, though. I switched to Apple maps navigation for a while because it avoids nearly all the above factors (fewer static elements, dark theme by default, actually turns the screen off during long stretches of "keep going straight for 40 miles") but eventually went back because I'm so used to the Google maps UX (and I stopped driving such long distances regularly).

iPhones with OLED displays do have burn in. Interestingly some part inside the screen assembly seems to try to compensate for the burn in somehow. Check out this repair video on Youtube:

https://www.youtube.com/watch?v=46KdDH5tSic

When you change the screen on an iPhone without pairing it correctly, the new screen will have the same burn in patterns as the old one.

uLED works but only at large sizes.

Answering to All comments. I am old enough to remember when I first read about OLED too :) It was 1997 in WH Smith ( A book store in UK, ). It was mentioned as the Holy Grail of Display Tech. And I have been following it loosely ever since.

Burn-In, It is an issue. But specific to certain usage. The above was written mostly in the view of Smartphone. Apart from gaming, Top quality OLED panel burn in issues on Smartphone is rare due to your usage on smartphone, you dont use the same App for prolong period of time. ( So dont expect OLED on your computer soon, it makes no sense. )

OLED is also a spectrum of technology, WOLED are less susceptible to burn in, along with Quantum Dot OLED. Again with a roadmap to further improves these situation.

And I did mention QNED [1] , Nanorod SolidState OLED that drastically improve everything from brightness, efficiency, burn in and even cost. Although that is somewhat 5 years in the future.

The difference between comparing to LCD to OLED and OLED to uLED mostly comes down to cost / benefits. OLED was thinner, lighter, more efficient, profitable than LCD. There is nothing on LCD roadmap that could compete with OLED for Smartphone display. Nothing. There is a reason why even low end Smartphone are switching or planning to switch to OLED display. Entry Level OLED and LCD price are already level except LCD are virtually operating at a zero margin, while OLED are profitable and with a roadmap in this decade to further dipping below $10 per panel for average sub 6" Smartphone Display. ( Ask BOE ) And a whole positive feedback loop to further evolve the spectrum of technology.

Again this is mostly looking at Smartphone. We could see uLED take on TV and large size display where OLED dont make sense. But then uLED is also a spectrum of technology and those used in the current Samsung and Sony Wall Size TV aren't the same as those that wants to fit in to tablet and phone.

[1] https://www.displaysupplychain.com/blog/are-quantum-nano-emi...

> And I did mention QNED [1] , Nanorod SolidState OLED that drastically improve everything from brightness, efficiency, burn in and even cost. Although that is somewhat 5 years in the future.

Nanorod LEDs are not OLEDs but fairly standard blue leds.

Samsung got a 15 years headstart. I think they are going straight for skipping the mass transfer stage altogether, and growing LEDs on the glass. Their first working blue GaN led on glass was in 2011. 4 or 5 years since they launched the effort.

> There is a reason why even low end Smartphone are switching or planning to switch to OLED display.

Low end smartphone sized OLED screens are actually cheaper in China than decent LCDs from time to time.

Very interesting article. The writing style of author Laura Peters stands out to me, it is informative, filled with many short background explanations suited for laymen, to the point, factual, entertaining.

The possible leap in responsiveness cannot be overstated, such displays will probably solve latency issues plaguing alternative display technologies for good.

I cannot wait to have 1000+ Hz ultra responsive screens in any imaginable format.

Yes! I posted it for this, it’s nice to understand how a new (quite) technology is going to mass production.

OLED is plenty fast. It's everything else that is holding us back. It took the TV companies decades to move, reluctantly, beyond the silly 60hz cap

I am all for 1000fps games but by that time I won't be able to play them due to old age.

I don't understand why you care? 60hz seems plenty fast enough and there are a lot of things slower than that. We are usually waiting on networks, not displays.

Games can push more than 60 FPS easily, but a lot of TVs (I’d assume most) are not used for that and manufacturers can extract extra profit from premium models that enable that (even if the panels and electronics are identical because it’s cheaper to manufacture that way).

For me, personally, the benefit of an HDR panel would be much higher than faster frame rates.

When you're interactively controlling something, you're best off getting new frames in a small number of milliseconds end to end. Lots of the delays in the pipeline are measured in multiples of frames. There are serious improvements in the ability to click on things up to 200-300Hz, and going above that is less important but still not bad. For something that can toggle as fast as an LED, might as well go for 500/1000 and minimize jitter.

If the rendering pipeline adds multiple frames of latency, it seems like that's a separate problem that should be fixed and it would help a lot without raising the frame rate.

You pretty much have to buffer a couple frames because that's how rendering works. You can do work to reduce extras, but it only gets you so far. And screens tend to want to buffer at least a frame too, and it's hard to convince them not to.

You also need quite high framerates to make rendered motion come out reasonably smooth. Especially for something you're trying to follow across the screen with your eye. Fake motion blur only partially helps and has its own problems.

I wonder if it makes sense to render at 120hz internally but skip every other frame? That should have a similar improvement on latency as actual 120hz.

I agree that following things across the screen is a use case for higher rendering rates.

That helps, as does triple buffering at very high framerates, and various techniques to try to align rendering exactly with when a frame is needed.

But it's still significantly better if you put that 120+Hz output onto a 120+Hz screen, and it's not super hard to make them.

TVs have longer lifetimes than phone or laptop displays, so it’s safe to assume manufacturers would be more cautious. As for TVs, there’s not enough 60+ Hz content to justify much of a hurry. I’d be surprised if there were a significant amount of content above 24Hz.

I'm really hopeful that because these displays aren't (currently anyway) built as large planes and then cut to sizes, that we won 't be stuck with only the sizes and aspect ratios that cover the plane...

I've got arcade machines that want 25" 4:3 monitors, and maybe MicroLED could fill the void. A suitable CRT would be best, but those are hard to find. Modern displays don't come in 4:3 at that size, and specialty 1:1 displays are too expensive for me to even measure to see if they'd fit.

For an arcade can't you get away with mounting the screen vertically by hiding the rest of it in the cabinet?

On some machines, yes. Not on a sit down machine where your legs go under the screen, and there's stuff on top of the screen.

Maaaaaaaaybe, this machine could get by with an ultra-wide screen, because it's got two player stations next to each other with a partition in the middle, but that's a big maybe. Plus I'd need something to link the two independently clocked video feeds into a single wide display.

uLEDs would let us read outdoors without brightness throttling that makes OLED displays invisible with sunglasses on.

That would be a major improvement for mobile.

How is light to be modulated with these? They're not going to use PWM, are they? I'm pretty tired of seeing displays that exhibit visible flicker when a camera is pointed at them, especially as flicker imperceptible to the human eye can still be migranogenic.

The effect largely goes away if the frequency exceeds 4 kHz, as even the quickest saccades would see a blur rather than a flicker. putting the flicker above 20 kHz would be ideal, because that way it is well beyond both visual range and even any noise generated by the circuit would be inaudible. The real question is why higher frequencies aren't used for driving LEDs. They have very low cycling latency, so it's a no-brainer.

> They have very low cycling latency, so it's a no-brainer.

I read somewhere that that makes it difficult to accurately control the brightness. With HDR content already requiring 10 bits, anything that interferes with that is a problem. Future panels might require 12 bits or more.

In the mini-led industry the clocks are often much higher. That said, you are limited by scan (how many LEDs driven per driver chip), because the clock is divided among the driven LEDs.

Consider that raising the PWM frequency doesn't automatically solve the problems you raise. 20khz PWM can still have audible harmonics, for example. In the mini-LED industry there are actually spread spectrum/randomized PWM approaches to address this, and to help with EMI.

> 20khz PWM can still have audible harmonics... there are actually spread spectrum/randomized PWM approaches to address this, and to help with EMI.

!! Great.. now I have to consider Tempest shielding for all the displays; I had thought once CRTs went away, we'd be safe...

Any guesses who may be the first to market with a uLED micro displays?

Apple Watch?

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