Tandem OLED is OLED's latest weapon in holding off MicroLED, QDEL | Hacker News Reader

Tandem OLED is OLED's latest weapon in holding off MicroLED, QDEL

arstechnica.com

84 pointsrbanffy49 comments

I thought MicroLED was not really ready to compete outside a TV-sized form factor due to the difficulty & costs to manufacture it at competitive resolution density for phones/tablets? Has that changed substantially since Apple cancelled it's MicroLED project for the Apple watch?

Manufacturing is still the biggest bottleneck, but resolution density is very achievable. Jade Bird Display is a manufacturer I follow as they make extremely dense, high refresh rate, high brightness microled displays for projector purposes: https://www.jb-display.com/.

The main product they sell are monochrome 3.3mm 640x480 displays (1 million nits!), but they do have 2k resolution 5.6mm RGB displays: https://www.jb-display.com/company/127.html

Aren't the tiny displays manufactured all on a wafer, bypassing the need for assembling all the individual LED elements that causes problems for the TV-sized displays?

No. The pixels still need a transfer step

yea it seems that microled is good at either being really big (110" TVs) or really small (VR headsets), but nothing in between yet.

> or really small (VR headsets)

That's MicroOLED in the Apple Vision Pro, not MicroLED. Confusing, I know.

I'm not talking about micro OLED. I'm talking about microled which is indeed made in small chips with VR and AR as the target market.

For example the recently announced Meta Orion is said to use microled [1].

At the recent microled connect conference there were lots of VR/AR focused talks [2].

[1] https://www.microled-info.com/meta-announces-10000-ar-glasse...

[2] https://www.microledconnect.com/current-agenda

Er, no.

It's not shipping today for anything smaller than 8 foot TVs, and doesn't have a path.

It's been 5 years away for at least a decade.

OP is referencing Apple Watch cancellation because that was Apple throwing in the towel in microLED after a decade of investment, making it likely no one expects it to be solved soon.

[1] Facebook is using a MicroLED projector and expressly says the display is an unknown unknown, because they can't ship this one if they wanted to. The failure rates are too high (see manufacturing process in [2]).

[2] has been happening for at least 8 years. It'd be awesome for VR, but that's the least likely near term option because right now it boils down to "manually place 8,294,400 pixels and if any have errors, do it again." Its shipping at eye-watering prices in Samsung TVs > 100" (read: have "huge" pixel sizes so they can be manually placed)

They're still doing pick and place with millions of individual LEDs.

Oh, no, we don't use pick and place for micro LED. We use LASER-Induced Forward Transfer - ie we blast the LED straight off the wafer and onto the screen substrate and precision-align it with another aimed laser pulse.

What's annoying is that this tech already existed for LCD screens. It supposedly had deep black that OLED brings but at LCD prices. If the quality is similar / no better, it's frustrating to see tandem tech never made it out of China.

Those Hisense tandem LCDs had some significant issues that they weren't able to iron out, they had trouble with poor response times, ghosting, and color banding. Flanders Scientific also used to make tandem LCDs for ultra-high-end professional monitoring, which was a market that could tolerate high prices and poor power efficiency in the name of performance, but even they have migrated their HDR monitors over to QD-OLED now so I think the consensus is that tandem LCD is a dead end.

Dual-layer LCD is best thought of as a separate technology from tandem OLED, due to being transmissive rather than emissive. In many respects, it surpasses OLED, which is why mastering monitors used in Hollywood still employ this technology. Unfortunately, the poor efficiency and excessive energy consumption/heat output have hindered its adoption in the consumer market.

> In many respects, it surpasses OLED, which is why mastering monitors used in Hollywood still employ this technology.

Flanders Scientific were the main champions of dual LCDs in that market, and even they have phased out all of their dual LCD models in favor of QD-OLED ones now. I think they just brute force through OLEDs usual brightness limits by actively cooling the panel.

Sony also makes dual-layer LCDs, they even introduced a new model in 2023: https://pro.sony/en_GB/products/broadcastpromonitors/bvm-hx3...

Good to know, but that spec sheet neatly demonstrates the efficiency challenges of dual-layer LCD. That's a 31" panel which burns up to 610 watts!

Also, it costs $25,000. But that might not be related to it being a dual-layer LCD, but rather other exacting tolerances for professional mastering use.

That's probably illegal to sell in the EU?

Those rules and regulations only apply to consumer products, business/professional products are exempt. This product is obviously not a consumer product.

It's a professional reference monitor not a TV so maybe there's an exception.

Dual LCDs also have poor brightness since a lot less light gets through the two layers. That can be overcome by a much stronger backlight, which produces tons of heat that require active cooling.

And speaking of high-brightness LED panels, I can swear I got a tan from one during a conference where the panel was sitting with the back towards the panel.

Those things are hot and very bright.

>It supposedly had deep black that OLED brings

How does stacking displays let you get pixel level light emission of OLED or better blacks in general? The issue with LCD is that there is a display wide backlight so you have to actively block out the the backlight to make black. Even if there was some tech to stack something that added more blocking (I guess, adding another liquid crystal layer? Another polarizer? I admit to not really understanding the tech beyond a surface level, just trying to understand.), it doesn't seem to be the same tech as stacking OLEDs which is to get more brightness/less burnout. And if you mean stacking more light emission as in the case of OLED, that also wouldn't seem to contribute to better blacks.

Two LCDs, front to back, provide much better contrast by blocking more of the light in the liquid crystal layers.

The rear one is greyscale.

https://www.reddit.com/r/hardware/comments/w0u2rf/did_dual_l...

https://www.rtings.com/tv/reviews/hisense/u9dg

>The rear one is grayscale.

If I understand correctly, you're saying that there is a rear LCD that only either lets light in or blocks it without caring about the color? That's interesting. As for why they aren't investing in this then, it's might be at least in part due to the power usage which would make it unsuitable for battery powered devices such as the iPad mentioned in the article.

OTOH, an LCD, at best, let's 50% of the light pass through it, so, for two stacked LCD panels, you'll need a much brighter backlight.

LCDs work on polarization... you typically have an unpolarized source, run it through a polarized filter which is where your 50% loss comes from, then the LCD changes or doesn't the polarization, and you run it through a filter again. If you stacked a second LCD, you shouldn't see a second 50% loss, the light is already polarized by the first LCD.

You are right - the 50% loss comes from the filters, but I forgot to count the loss from the filters. You could add a second monochrome LCD on top of the first one for the same result.

I must be wrong, because this sounds very trivial.

There's a diy perks video about making your own which goes into the pros and cons for the curious.

Due to the way LCDs work it’s never useful for a consumer monitor. The backlights needed to punch enough lumens through 2 layers of LCD is prohibitively large/expensive, and the cooling needed to make sure you don’t burn it out leads to a pretty thick and bulky design. Take a look at the professional monitors like this… there’s a reason why they’re so thick, and it’s not because they’re “industrial” or something. Also, power consumption is atrocious.

This sounds like a problem that PixelQi tech could solve - it used prisms instead of filters for colours, which reduced light absorption on inactive LCD pixels, so if the lower LCD is a PixelQi panel, you can add a set of filters with the second LCD panel and drive the backlight harder to gain better contrast (a problem with PixelQi) within the same power envelope of a "regular" LCD.

I don't have much to add to this conversation except that what a lot of people don't realize it that 2k, 4k, or 8k, tv means very little in terms of how nice the picture looks. Yes to a point that is important but I always tell people the panel technology is way more important. Some TV's look absolutely lifelike, maybe beyond life like and some sort of hyper-reality. It is like a massage on your eyes watching things on a superior TV. But those TV's cost a lot. A brand I found that is very good for the cost is the HiSense ULED TV's. Costco has them. I love the picture for the affordable cost. Not the best but pretty great. I have an led monitor beside my HiSense TV, both hooked up to my pc and I ran a pure black YouTube video on both side by side and the difference is huge. The led monitor looks grey and is clearly lit up from the back light. The HiSense is absolutely pitch black dark zero light emissions. There is no real point to this post other then to say I am happy with my TV, it definitely is great for the cost.

I love OLED panels and their amazing color reproduction, but I'll never buy another device that uses them ever again if I can help it. My current laptop developed pretty horrific burn-in after just a couple years of regular use, and there wasn't really anything that could be done about it, as the burn-in is comprised entirely of my taskbar and the UI elements of my web browser which is far and away my most used program / application and likely is for the majority of other laptop users as well. I'm sure they're fine for TVs where content is played "Full screen" 99% of the time, but for phones or PCs where there are common OS or web browser UI elements displayed on the screen the majority of the time the user is using their device, they just don't make sense.

I wonder if more aggressive anti-burn-in measures could help. Unfortunately, on a laptop you don’t want to run the screen on full blast for a long time since it’ll run out your battery. I have a QD-OLED desktop display that has some very mild burn-in after maybe two years, and I try to baby it as much as possible by using dark mode, etc.

All I have to say is that the tandem oled on my ipad pro still, everytime I use it, makes me wow. It is an absolute pleasure to look at and watch things on. It feels like I'm watching real life and I love it.

I spent a few minutes at an Apple Store holding an iPad Pro with tandem OLED, and I couldn't perceive any difference with the iPad Air right beside it.

(The even more expensive nano texture option was worse. It simply felt blurry.)

That would be a worse case scenario. The Apple stores are incredibly brightly lit, and you’ll be hard pressed to notice wining isn’t differences between any display type in such an environment.

These displays and their content are intended to impress in media viewing situations in which you’ll light control accordingly. They’ll still look good outside of that, but they offer so much more when you want to dim the lights and kick back with one on the couch with a movie or whatever.

Now if I could only get one in a size I cared about, I could be rid of LCD permanently. Alas, I doubt I’ll see this in a size suitable for what I want it for in less than 5 years or more.

There have been rumors of the MacBook Pros moving to OLED for a few years now.

Seems unlikely they’d redesign with something worse than the iPad Pro.

I wonder if they’re waiting for yield issues on larger panels or if it’s just pure cost at the moment.

One needs to use them in their personal lighting situations, not in a store.

I have both the current and prior iPad Pro version. IPS+Mini LED and the Tandem OLED. The IPS version was already great. The Tandem OLED is generally better, but often not by that much. It's also a bit brighter. Both are quite a bit better than the normal iPad displays.

I've seen the nano texture version of the Tandem OLED. Reflections are much less, but in brighter surroundings, the image is not that dark. But again, it all depends on the personal lighting situations.

The amazing thing about the nano texture is how it absolutely kills reflections compared to the normal option.

I agree there is a sharpness sacrifice to get there.

Using it in a dark room is weird at times. The pure blacks create the strange illusion of holding something lit that you cannot see.

>"Once blue PHOLED finally becomes available in 2025 or 2026, most display makers will integrate them in their OLED displays (single or tandem) and deliver further improvement in lifetime, brightness, and efficiency," Virey said.

This is much more important improvement than Tandem OLED. Although I dont think I could see that on an iPhone before 2030 judging from how slow Apple adopt technology.

> how slow Apple adopt technology.

Aren’t they only slow to adopt new display technology.

Everything else they either lead or are on par with, no?

Biometrics, Spatial Audio, health sensors, SOS phone calls, etc.

Apple was also first to bring multitouch and high DPI displays to consumers.

They were slow with OLED, and they have also been slow with each new generation of cell phone radio standards.

The early ones likely weren’t up to their quality standards. Then at some point they may have decided to hold it for the X redesign.

The main issue with cell phone standards appears to be power. Apple doesn’t like using radios that use up so much power the user has to turn them on and off to manage things the way early 4G or 5G android phones were set up. They seem to prefer to wait until a lower power version is available that they can leave on all the time without significant issue.

> first to bring multitouch and high DPI displays to consumers

If you discount the LG Prada, then yeah.

That one was capacitive, but didn’t do multitouch. So no pinch to zoom, which was one of the most wow things the first iPhone did.

Agree, and once you can lithographically pattern QD in for Red/Green it'll just be one layer of Blue PHOLED underneath. Cheaper and matched wear-out so burn-in is less visible. These aren't huge changes, but the steady pace of improvements may just make the other technologies irrelevant in mobile devices. TVs and wearables still might go to microLEDs, but only if the costs can come down.

Samsung originally toyed with this idea but with Nanorods. Now that is abandoned for unknown reasons. ( Likely cost ).

Blue PHOLED also has life time issues. And we will need may be another 5 years of R&D along with 3 years to market. Definitely post 2030.

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