Is MicroLED the be all end all for display technologies? Perfect blacks, high brightness, no burn in, no bezels, thin. It's hard to imagine another display tech displacing MicroLED once it takes hold. Does it have any theoretical downsides other than cost?
In theory, yes it's about as perfect as a screen technology can get. I'm sure earlier implementations will have quirks that make it a dealbreaker for particular applications/users, but that'll work itself out in time.
I'm looking forward to it. I'm happy with the OLED panels in my phones but with how long static elements are visible on my computer monitors and TVs I haven't been able to justify buying OLED for those with how even the best can still exhibit burn-in. Once there's microLED monitors and TVs with performance equivalent or better than current QD-OLED panels I'll be buying them immediately.
> I haven't been able to justify buying OLED for those with how even the best can still exhibit burn-in.
My oldest OLED TV will turn 6 in August and has exhibited no burn-in.
I think it ultimately comes down to what you're watching. You're likely to experience burn-in if you watch something with a persistent banner like 24 hour news.
For example, my 2 year old LED VA Panel monitor already has burn-in where the task bar is displayed.
Yup. When the kids were younger, we always had Disney junior on. Mostly because I always like to have a bit of background noise (this kids didn't actually watch it that much) and it was kid friendly. The Disney junior logo burned into the screen.
The risk is lower but still present on my TV, which spends a large percentage, maybe even a majority of its powered-on time playing games with static HUDs. What I'm really worried about is computer usage… the Windows taskbar and macOS menubar specifically. Both can be set to auto-hide but I'd really rather not have to do that, particularly for the Mac global menubar.
And yeah, I've experienced image retention on non-OLED screens. the LG-made 2560x1440 IPS panels that used to get used in 27" iMacs would after a few years start exhibiting image retention, though it'd at least fade if the static elements that sat long enough to cause retention were hidden. I think this was caused by the heat generated by the computer part of the iMac though, because the Apple Thunderbolt Display that used the same panels never develop the issue even after a decade+ of usage. I also haven't seen it happen on any other IPS panels I've owned.
I haven’t experience any burn in issues with my OLED or even image retention which I sometimes see on my Plasma.
I think for normal TV usage it is a non issue. The only times I have heard it being a problem is when someone leaves their TV on for a week for their cat or something.
It's a whole area of the screen. Shifting by a few pixels doesn't do anything for a whole area. It'll help only with thin text, but that's the element that tends to mostly change on its own anyways.
If you want to rotate the task bar or dock or menu bar around all four edges of the display every day then maybe, but that'll be hell on your habits and muscle memory.
I actually think there are no major issues apart from the enormous costs. But costs don't always get outweighed by higher performance. The reason why OLED-Displays were (and are) so successful wasn't just that they had better contrast than LCDs, it was also that they were not massively more expensive.
Compare that to Intel's Optane, the elusive PCM memory technology which finally arrived to take out NAND Flash. Sure, it was faster than Flash, but it was also massively more expensive. It wasn't worth it for most people. So Intel recently discontinued it.
The same could happen for Micro LEDs. It isn't clear whether their quality advantage over OLED is worth a much higher price. Their main advantage over OLEDs (higher max brightness) doesn't seem too relevant anyway.
> Compare that to Intel's Optane, the elusive PCM memory technology which finally arrived to take out NAND Flash. Sure, it was faster than Flash, but it was also massively more expensive. It wasn't worth it for most people. So Intel recently discontinued it.
Intel Optane is barely faster than flash — roughly 3x (for 4k random read) compared to the fastest Samsung SSD [1].
Optane was a failure because it failed to deliver the promised result. Intel would have never poured money into a new technology only three times faster than an existing technology. I recall initial promises were RAM-like speeds.
If Apple is able to spit out 200 million of these screens in a year, I have a very hard time imagining what ingredient could go into the production causing a greater per unit price than a Samsung display.
> Intel Optane is barely faster than flash — roughly 3x (for 4k random read) compared to the fastest Samsung SSD [1].
... and the maximum brightness advantage of micro LEDs may be similarly (un)impressive.
> Optane was a failure because it failed to deliver the promised result.
No, it only failed because the performance/price ratio wasn't good enough compared to NAND flash. That's exactly what I was saying: Both performance and price have to be considered.
> If Apple is able to spit out 200 million of these screens in a year, I have a very hard time imagining what ingredient could go into the production causing a greater per unit price than a Samsung display.
Replace "Apple" with "Intel", "screens" with "Optane disks" and "Samsung Display" with "Samsung Semiconductor", and you see that this argument doesn't work.
uLED will have one major victory over OLED - longevity of the display.
Source: Where I work is tooling up to start producing uLED products for SLA 3D printing. UV uLED + LCD filter all in one. I'm having to teach them how to utilize LIFT.
Higher max brightness is very relevant. most Oled tvs in recent years max out at something like 800-1000 nits. Dolby vision content can be mastered at up to 10000 nits I believe and microled tvs could provide that brightness.
There's something incredibly realistic about highlights being super bright, I think it's going to look more like a window than a TV.
HDR LCD TVs also had significantly higher maximum brightness than OLED TVs, but that advantage apparently didn't matter much compared to the finer contrast and lower black levels of OLED. I think smartphone LCDs were also brighter than OLED displays. It then questionable whether the better maximum brightness of micro LEDs will outweigh a much higher price.
More "if" rather than "when". It's far from obvious whether they will be successful. They just have a higher maximum brightness, and a large cost cut is not guaranteed.
The only technology I've heard of that might outperform it is directly-driven nanorods, something Samsung has been experimenting with. These are basically the same thing as "quantum dots", except that instead of small round crystals they are rod shaped. Apparently if they're aligned and excited by an electric field, they glow with a pure colour. This makes them very similar to microLEDs, but potentially much cheaper to manufacture.
However, other than some breathless press-releases a few years ago I haven't heard anything happening recently, so it's possible the technology didn't pan out.
Super cool, I asked Master GPT-4 to teach me about these nanorods and they sound super interesting. Exciting that they could be used for flexible/transparent screens and are lighter on battery, that would make AR devices much more seamless.
Why can’t they reduce voltage to each pixel to reduce brightness? I don’t see this as a fundamental limitation of the display technology, PWM is just easy and cheap to implement.
LEDs tend to change emission wavelength when changing the current. This is quite an issue if you want to combine them in an RGB display, because the human eye is extremely sensitivty to relative color variation.
I'd love a source for this claim (not sarcastic, I really would). I've have done a lot of testing of LEDs for scientific uses and my experience and what I've read show that temperature is what effects the center wavelength of LEDs. Not current/voltage. The reason for this, is that in monochromatic LEDs (so not white LEDs which have a phosphor coating) the emission wavelength is defined primarily by the bandgap in the semiconductor material. This bandgap is the difference in energy between the valance electron band and the conducting electron band (and this band "gap" is the reason for the "semi" in semiconductors).
This bandgap corresponds to the photon energy of the emitted light as electrons get excited due to the applied voltage as electrons are excited to the conduction band and then relax back to the ground state giving off light.
The bandgap energy changes as a function of temperature. The primary reason for this is that the lattice constants increases as temperature increases. This causes the bandgap to decrease, meaning the energy of the photons is less giving a longer wavelength.
The opposite effect is also true, cooling a LED will lead to a shorter wavelength. Here is a cool video showing the effect![1]
Increasing the current through the LED may change the temperature by a little bit but you need large temperature changes to have any effect.
The temperature has a much greater impact on the intensity of light emitted by the LED. I have seen a typically 1% decrease in intensity per degree C for the LEDs I have tested. This is the effect that matters most when using RGB leds as if the red led gets dimmer cause it is hot, than the green or blue, it will be seen as a color change, even though the center wave length of its emission is unchanged.
I mostly just wanted to share things I have learned about LEDs over the past year or two and your comment gave me a good opportunity!
While not a source I would wager that the LEDs are already driven close to the bandgap (for efficiency's sake) and meaningfully lower voltages would cease to produce any light output - necessitating PWM to control brightness.
I could plausibly see some color shift at close to bandgap voltage if there isn't a perfect uniformity in bandgap across a diode, inconsistent or even just gaussian distributed doping would result in some holes being preferentially excited if there isn't a sufficient surplus V?
> Digital pulse-width modulation is well-suited to driving microLED displays. MicroLEDs experience a color shift as the current magnitude changes. Analog schemes change current to change brightness. With a digital pulse, only one current value is used for the on state. Thus, there is no color shift that occurs as brightness changes.
I was commenting based on my recollection of this article. Granted it's for AMOLED, so it may not apply to microLED.
In this regard, AMOLED displays have a strong disadvantage. If you feed less voltage to the organic diodes, not only do they limit their brightness, but their color also changes, so that there might suddenly be visible differences in the color reproduction.
Is there a reason they couldn't just jack up the PWM frequency? Most OLEDs seem to be under 500 Hz[0], which leads me to believe that there's something limiting them from performing any faster. Basic LEDs on the other hand can easily operate at frequencies in the 1-5+ kHz range and can be pushed very far if the entire system is designed well. A display running at 10 kHz might not be noticeable to even the most sensitive people.
LEDs central wavelength changes with current. Some flashlight enthusiasts will not touch current regulation and prefer to use PWM because that means the color output does not change. From what I understand you can even use this effect to calibrate a diode laser to a specific wavelength(within reason).
This is not really a problem, you can away calibrate the differences on a pixel-by-pixel basis on each frame with modern mobile GPUs.
The bigger challenge here is pixel architecture, but if apple is actually slicing up wafers into a couple million pieces to build these displays, they are already sort of moving away from the typical TFT architecture and may be able to integrate more complex pixel drivers, potentially including things like touch sensors directly onto the pixels.
It is not possible to calibrate it away without knowing what the central wavelength of the LED is. That would require a spectrometer and if you manage to build one on chip per pixel which is currently not possible/practical.
I don’t understand what you mean with the GPU. It is has no information about the exact color of the LED.
This is equivalent to saying that you can't build a color-accurate display at all because you don't know the central wavelength. Not only is this inaccurate (LEDs are binned for exactly this purpose), but brightness variations are by far the greater contributor to display inaccuracy.
The shift in wavelength is primarily determined by temperature and current, and they work in opposite directions so sort of cancel each other out. And in any case, we're talking about well-characterized shifts on the order of a few nm over the operating range. The eye's cones are broadband, so you're not going to notice wavelength shifts, especially compared to the brightness variations over the same range.
This is a big deal for white LEDs because you have no control of the resulting color temperature (the phosphor emission and blue component wholly determine the output), but for an RGB structure, you have pixel-level control over each component.
I am sure your right about the eyes. But I would posit that most people wouldn’t know uncalibrated from calibrated anyhow. So seems like a moot point.
As to binning LEDs that works because it is constant. You can calibrate it once and done. But if you change the brightness by changing the current, it means your calibration is out of wack. Perhaps you can make a calibration at multiple current settings, but that seems inconvenient when using PWM will achieve the same thing.
I'm sure you could calibrate a compensation in theory (don't know about in practice), but that would also necessarily decrease the display color gamut, no? It's not like you can produce "all" the colors from any three primaries -- they have to be very specific.
So if the color shift is noticeable enough to require correction, then it's definitely enough to substantially decrease the color gamut as well. And so a range of wider-gamut colors simply can't be compensated for at all.
> manufacturing limitations mean you can't easily have those per-pixel while still keeping the whole thing cheap
“can’t easily” seems to imply it is possible. If that’s true, Apple, with its deep pockets, should be able to do it.
Also, I don’t think Apple will be bothered much with “keeping the whole thing cheap”. They will want to prevent it from getting expensive, but likely will accept intermediate costs if the result is much better.
Seems to be a limitation of our modern times rather than the display technology. I'd hope to see PWM free displays in the future as our micro LEDs improve.
For VR headsets the real buzz is around MicroOLED not MicroLED. Samsung just bought a small MicroOLED manufacturer with a technology that offers much higher brightness than other methods, which is important for virtual reality headsets.
I’ve read somewhere that one potential issue is that due to microLED color primaries having more narrow spectral bands, individual variations in color perception become more pronounced, leading to differences in how people perceive the colors of microLED displays.
In addition to flicker (discussed in sibling comments), I imagine they have problems with power + glare just like any other non-reflective display technology.
OLEDs have almost perfect Pixel Refresh Latency (< 1.5ms). MicroLEDs are still just LCDs with a better backlight but LCD Tech has evolved quite a lot and pixel refresh time (< 3-4ms) is not much of a problem anymore.
You may be confusing MiniLED and MicroLED. MiniLED still uses an LCD with multiple backlights and local dimming algorithms to improve contrast. MiniLED is pretty impressive and the quality of it is generally 1-to-1 with the number of backlights/dimming-zones.
MicroLED is more akin to OLED where each pixel is self emitting. MicroLED is almost the holy grail of displays and will more than likely obsolete MiniLED.
> MicroLEDs are still just LCDs with a better backlight but LCD Tech has evolved quite a lot and pixel refresh time (< 3-4ms) is not much of a problem anymore.
You're thinking of MiniLED, which is just better LEDs behind an LCD.
MicroLED is a whole different ball game, with no LCD at all. It's just red, green, blue LEDs, one for each pixel.
