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Seems like the initial deployment of the microLED's into a smartwatch makes some sense.. But unclear how this would make any sense for a large size phone displa
by xt00 9y ago
Seems like the initial deployment of the microLED's into a smartwatch makes some sense.. But unclear how this would make any sense for a large size phone display. The sheer quantity of LED's that must be placed properly on a glass substrate would be quite high.
However, the promise of microLED is pretty impressive if the manufacturing can be pulled off.
Basic idea is small high performance LED's of Red, Green, Blue, that are of the inorganic variety -- so much higher performance than OLED. They can be larger fill factor since they are diced from a wafer and can be basically any size -- vs. OLED where each color is limited in size due to the manufacturing process -- basically due to the size of pin-holes put in a mask that hovers above the substrate surface (called a fine metal mask).
The power, brightness, lifetime, and stability all likely would be quite high with the inorganic microLED's.. However, the cost is the challenge for sure. Its essentially equivalent to buying a bare wafer with millions of red, blue, and green LED's -- per each display. So say you want a 4kx2k display, well, that is 8 million LED's. If each one costs say $0.001 (a tenth of a cent), well, you have 3 * 8000 USD, so $24,000... so... clearly they need the LED's to be really, really, really, cheap -- say 10,000 per dollar.. which in the world of LED's would be super crazy crazy crazy cheap.
- coldtea 9y ago>Seems like the initial deployment of the microLED's into a smartwatch makes some sense.. But unclear how this would make any sense for a large size phone display. The sheer quantity of LED's that must be placed properly on a glass substrate would be quite high. How would it be different than producing screens for e.g. 10 watches (or what the analogous real estate is)?
- sebiol 9y agoI guess it would be about the ratio of the price for the screen compared to the device. Smartwatch at 600$ with a small screen vs. a smartphone at 1000$ but with a 10x bigger screen. With 10 smartwatches I would have 6000$ to spread the additional cost over. [edit] typo
- coldtea 9y agoAssuming the same (as current) prices for iPhone and smartwatch, that would be the same ratio though if we divided by the current models, so it doesn't tell us much regarding how might the new kind of screens affect price. Only something that took into account the relative cost of each type of screen would (and, if screen area is a non 1x linear factor of cost, that too).
- 6nf 9y agoEvery pixel on the panel must work, otherwise the whole panel is useless. Now imagine you have one broken pixel on average for every million pixels. Apple Watch screens have 100k pixels so on average 9 out of 10 screens test OK and can be used to make a watch. But the iPhone has about a million pixels, so you end up throwing away about half of all the screens you make. More pixels = lower yield.
- kilotaras 9y agoProbabilities works out even worse. For million pixels roughly 37% of screens would turn out OK.
- uptown 9y agoCould smaller adjacent panels be coordinated to appear imperceptibly as if they’re a single panel?
- cptskippy 9y agoPotentially, that's how led billboards are assembled.
- nonbel 9y agoSomethings off. It should work like this: p = 1e-6 n = 10^(1:7) frac_accepted = (1-p)^n Results: num_pixels frac_accepted 1e+01 0.9999900000 1e+02 0.9999000049 1e+03 0.9990004993 1e+04 0.9900498288 1e+05 0.9048373728 1e+06 0.3678792572 1e+07 0.0000453997
- Retric 9y agoThis assumes each failure is independent. Often a single failure will cause many bad pixels on the same screen. So you might have 98 good screens 1 with one bad pixel and one with 5,000 bad pixels when the per pixel odds say you are going to end up with 1 good screen if you are lucky and 99 bad ones.
- rasz 9y agoDidnt Sony demonstrate such display in a TV once? Yep in 2012, so did Samsung recently http://www.zdnet.com/article/ces-samsung-unveils-modular-146-inch-microled-tv/ http://www.zdnet.com/article/ces-samsung-unveils-modular-146...
- kosievdmerwe 9y agoThere's a substantial difference in DPI, which probably makes it easier to make this big screen than an iphone screen with near the same resolution.
- xt00 9y agoYea for the big TV's I think its basically like pick and place for the LED's.. the TV is essentially a giant PCB covered in around a million or so LED's.. which is pretty ridiculous that they tried that, but pretty awesome anyway..
- mozumder 9y agolol these things aren't going to be priced per LED. Just like you don't pay per transistor when you buy a chip, you're not going to pay per diode when you buy a microLED display. The costs scale with device area, not device count. This is because these devices are made with lithography on a wafer. A single silicon wafer would produce 5000 diodes, or it may produce 5,000,000, depending on how small you make each one.
- robotresearcher 9y agoThe cost of the equipment to produce the wafers grows with the density as well as the area.
- amelius 9y agoYeah, but it can be reused. We're talking about large scale fabrication here.
- robotresearcher 9y agoOh shit, I've been doing it wrong. It's been really expensive.
- xt00 9y agoOf course, so let’s assume a 5” display, and assume that the fill factor per LED color is 25% (rather than expected 33%) then 25% of the area of a 5” display would be required to populate one color. So assuming a small dicing kerf let’s assume for a 12 inch wafer you get 8 displays from that for one color. Which feels pretty generous, normally that same vendor would have yielded millions of LEDs from that same wafer and they made say 10000 per wafer, then if you asked them to sell for far less than that, what is their incentive? If they did that they would essentially be crashing the entire LED market in one fell swoop and their own profits. So the die area argument makes sense from apples perspective but doesn’t from the entrenched LED makers perspective. So seems like apple essentially would need to own the actual LED fab as well.
- 9y ago
- Someone 9y ago”So say you want a 4kx2k display, well, that is 8 million LED's” 24 million, if you want RGB. On the positive side: OLEDs have the same number of LEDs, and we can manufacture them economically and at large sizes (LG showed a 88 inch 8k one in January (http://bgr.com/2018/01/01/lg-8k-oled-display-announced-88-inches-need-right-now/) http://bgr.com/2018/01/01/lg-8k-oled-display-announced-88-in...)
- vardump 9y agoThat'd be true for large displays, but not for phone OLED displays. Phone OLED displays seem to have only 2 LEDs per pixel. See: https://en.wikipedia.org/wiki/PenTile_matrix_family#PenTile_RGBG https://en.wikipedia.org/wiki/PenTile_matrix_family#PenTile_... http://bgr.com/2017/11/07/iphone-x-display-microscope-oled-vs-lcd/ http://bgr.com/2017/11/07/iphone-x-display-microscope-oled-v...
- ferongr 9y agoLG OLED is not true color OLED, but a hack, having a white OLED emitting panel and a color filter on top. It has many downsides like lower efficiency, maximum brightness and color accuracy.
- NullPrefix 9y agoSort of like an LCD?
- ferongr 9y agoYes, though it still improves on the many problems of IPS and VA LCD technologies.
- TremendousJudge 9y agodoes it have true blacks at least?
- 9y ago
- baybal2 9y ago>The sheer quantity of LED's that must be placed properly on a glass substrate would be quite high. They will be simply grown on the substrate in-situ. A very different epitaxial pricess from bulk leds, but nevertheless very doable. Apple is known to have bought a Taiwanese company that was making monochrome microled screens for night vision goggles.
- kurthr 9y agoGreat job describing some of the real advantages and manufactuting challenges of microLED displays. The 320x320 pixel wearble displays seem like a place to start with only 100k pixels (300k sub-pix). With that number of pixels they'll be able to have decent yield at 1ppm defect rates. The power, brightness, and lifetime arguments are even more compelling for a watch. I don't think the cost side is so bad. LED wafers are only a few hundred $ at 8in for over 3M 50x50um2 die so ignoring other processing and placement costs they are in the right ballpark. Assuming they use some PWM or passive matrix method that keeps the power control substrate cost/yield reasonable they could have a very high performance square inch sized display for a reasonable price... soon? For any larger displays the dicing and KGD placement yield become a huge issue. Ultra-reliable reworm and/or uncorrelated defects become critical when you need to approach 10ppb for reasonable yield at WQ.