LPD: Laser Phosphor Display - Successor to CRT?

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valfranx
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Re: LPD: Laser Phosphor Display - Successor to CRT?

Post by valfranx » 26 Oct 2020, 13:50

I can see that blur busters are having a certain influence on the market decisions of monitors, to the point of arousing the interest of companies such as Sony, Optoma, Panasonic, LG, Epson, Xiaomi, BenQ ... that are currently doing research and reports on the demand for FED, SED and LPD screens in the manufacture of televisions, projectors ... websites such as stockmarketvista, aerospace-journal and prnewsleader covering news about the market have mentioned much the LPD, perhaps after the exhibition of the LPD 6k that they used in a presentation.

ChaosCloud
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Re: LPD: Laser Phosphor Display - Successor to CRT?

Post by ChaosCloud » 26 Oct 2020, 22:36

blurfreeCRTGimp wrote:
23 Oct 2020, 01:19
So, if this is the case why in the hell are we chasing mini LED, OLED, and other displays that have so much blur? Imagine how much more utility our GPUs would have if you could drive games at just 60hz and with lower resolutions?
I think the main issue is form factor. The mass market wants flat and thin, so manufacturers are working towards that. Same reason why the mass market moved from CRT to LCD, despite the many drawbacks of LCD. (I suppose that energy efficiency was also a driving factor).

Rear projection needs space. They look "old", which turns consumers off. Even if there were a 50" TV for $1500 with perfect colour, infinite contrast, UHD+, perfect motion - if it were a foot thick that would instantly make it a niche product (though it would sell well to the minority who care more about picture than external form).

I do think that there is a growing segment of the gaming community who notice and care about good motion, in no small part thanks to Mark's efforts here at Blur Busters. I think laser rear projection has the potential to deliver the best aspects of CRT, and it seems to be feasible with today's technology. Yeah, it's going to be "thick", but not nearly as bad as CRT, and I think there are enough people who would overlook thickness for the functional benefits.

The proportions of the later RPTVs were not even that bad. Here's a comparison of a 2008 Mitsubishi with Asus' latest 360Hz monster.
Granted, such compact RPTV geometry would need a very short-throw system, which I'm not sure is possible with current MEMS technology.
asus_mitsu2.png
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thatoneguy
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Re: LPD: Laser Phosphor Display - Successor to CRT?

Post by thatoneguy » 27 Oct 2020, 02:02

Chief Blur Buster wrote:
23 Oct 2020, 05:47

MiniLED and OLED can be very fast.
From what I've read from one of the earliest articles MicroLEDs have sub-nanosecond switching time. That's picosecond response time.
From what I remember reading somewhere CRT's have picosecond rise and fall though I'm not exactly sure.
It was found that the turn-on time is on the order of our system response (30 ps) and the turn-off time is on the order of 0.2 ns and shows a strong size dependence.
https://aip.scitation.org/doi/10.1063/1.1376152

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Re: LPD: Laser Phosphor Display - Successor to CRT?

Post by Chief Blur Buster » 27 Oct 2020, 14:49

thatoneguy wrote:
27 Oct 2020, 02:02
From what I've read from one of the earliest articles MicroLEDs have sub-nanosecond switching time. That's picosecond response time.
From what I remember reading somewhere CRT's have picosecond rise and fall though I'm not exactly sure.
The rise and fall time (GtG) is not as important as motion blur (MPRT). Those unaware can also read Pixel Response FAQ: GtG versus MPRT to understand that GtG is the pixel transition time (rise and/or fall), and MPRT is the pixel visibility time, which is more important for display motion blur.

From GtG perspective instead of MPRT perspective, CRT has near-instant rise time but slow fall time, which is why you see CRT phosphor ghosting. Also, CRT naturally is an impulsed (strobed) tech, so it's naturally zero motion blur, despite the fact that real life does not flicker/strobe. So CRT was just assumed as the Natural Way To Display Things. But that's not true (because of the flicker).

The Natural Way to Display Things is really analog motion (aka infinite frame rates) to bypass all the Stroboscopic Effect of Finite Frame Rates from the artificial humankind invention of digitally flipbooking through static images to emulate analog moving images. Instead, the Better way to emulate real life is brute framerates at brute refresh rates (as well as potential future theoretical framerateless displays; which is currently hard for most people to wrap their brain around, much like Quantum Mechanics versus Newtonian Math).

We can be perfectly happy with 0.1ms real-world GtG (100us) as long as it's consistently fast for all 65,536 transitions of an 8-bit panel (see The Complexity of Measuring GtG), if we're aiming at 1.0ms MPRT. To eliminate human-visibility of rise-fall issues (e.g. 0.1ms GtG100% for all colors, not GtG10-90% for a cherrypicked color) only needs to be a tiny fraction of pixel static time (e.g. the 1ms refreshtime). OLED is very good at doing this; witness 120Hz on an OLED; it follows Blur Busters Law almost exactly mathematically to a near-perfect tee, because Blur Busters Law (MPRT100% simple pixel mathematics) becomes beautifully perfect at GtG=0 about 1ms of pixel visibility time (MPRT100%) translates to exactly 1 pixel of eye-tracking-bsaed motion blur per 1000 pixels/second motion. Those unfamiliar with Blur Busters Law can read Blur Busters Law: The Amazing Journey To Future 1000Hz Displays as well as GtG versus MPRT, and understand the MPRT equivalence to a camera's shutter:

Image

Which means 240fps on a 240Hz 0ms GtG display, at the same screen panning speed (turning/scrolling/strafing + headturning in virtual reality), is exactly the same motion blurring as a camera shutter at 1/240sec for the same equivalent physical camera-panning speed.
TL;DR: 240fps on 240Hz screen = same blur as 1/240sec shutter on SLR camera

You know your smartphone photos become blurry if you pan while taking a picture, and it gets sharper if shutter is faster? Same thing with display refresh rates & frametime (pixel visibility time) on sample-and-hold displays. People still see benefits of ever faster and faster camera shutter speeds in fast-paced material, which underscores the need for geometric improvements to frame rates and refresh rates, needed to achieve blurless sample-and-hold.

In other words: [Rheoretical napkin-exercise self-question] Who cares about nanosecond GtG times if we're aiming at blurless sample-and-hold with MPRTs in the hundreds of microseconds. The motionblur of MPRT will hide the GtG, and you only need to retina-out MPRT sufficiently. Fast GtG is conveience; it simplifies strobeless low-MPRT engineering. Low strobeless MPRTs are impossible when GtG overlaps multiple refresh cycles (e.g. 33ms+ 60Hz LCDs)

GtG weaknesses are amplified/hidden depending on how you do it. During direct pixel strobing where rise/fall is GtG-powered, GtG fastness is important (i.e. strobed OLED or panel-based/software BFI) since artifacts from GtG:MPRT ratios is massively amplified in this situation. I'm using GtG(100%) and MPRT(100%) here, all colors, for math simplicity.

GtG-distortions in strobing: Now, GtG:MPRT ratio of 1:100 can still have human visible artifacts in strobing if strobing is GtG-powered, since a distorted curve in 1% of pixel visibility length may bump color shades of pixels a few shades off (like RGB(128,131,129) inaccuracy versus RGB(128,128,128) on a spectrum of RGB(0,0,0) to RGB(255,255,255), but consistent GtG can fix that.

GtG-distortions in strobless blur reduction: But during strobless blur reduction, GtG fastness simply need to below the MPRT noisefloor, and that's it, GtG:MPRT ratio is far more leninent and GtG is easily pushed below noisefloor. Focus on retina-ing out MPRT, and put GtG a bit below that noisefloor, and voila! GtG:MPRT ratio of 1:10 during 1000fps@1000Hz sample and hold creates a 0.1ms:0ms ratio. The blur difference is virtually unnoticeable at these scales, and a lot of color distortions (from GtG asymmetry between different color channels) are better hidden -- the blur of full-persistence MPRT more eawsily completely hides the GtG limitation once the GtG is a tiny fraction of a refresh cycle.

GtG:MPRT ratios are less critical during strobeless blur reduction. -- aka using brute frame rates & brute refresh rates. It was a big problem when LCDs were so slow, that real-world GtG overlapped refresh cycles. But in the discussion of nanosecond LED switching times, it's meritworthy for a scientist/researcher to understand what nanoseconds is important and what nanoseconds is less important, for specific nuances of display engineering. When you build a LED display, you practically never have to worry about GtG limitations (until you are dealing with long tiny microwires trying to switch distant transistors), and can thus focus on other priorities.

Just like Henry Ford went through the dumps in the 1920s looking at rusty cars to figure out which Model T Ford car parts wore out more than others, to figure out how to make parts more cheaply and other parts more durably -- sometimes you discover overkill and discover what's important. Realworld GtG100% just simply need to be a tiny fraction of MPRT100%, and it's really game over. That said, GtG inconsistencies can lead to color calibration difficulties (e.g. slower pixel responses for certain colors creating tinted distortion in ghosting/motionblur). But direct-color LED (no white phosphor) generally has none of that problem so we can consider GtG equal and easily realworldable for all color combos. Now the correct engineering target thusly become MPRT, and thus raising brute refresh rates and brute frame rates. Prioritization FTW!
It was found that the turn-on time is on the order of our system response (30 ps) and the turn-off time is on the order of 0.2 ns and shows a strong size dependence.
Deliciously fast. But we're still limited via very low pixel refresh rate, but it's actually easier than expected to get kilohertz refresh rates via parllelized scanout logic on MicroLED modules. For example, JumboTron modules (the 32x32 or 64x64 RGB LED metrixes that you can buy off Alibaba or ALIexpress for under $10 each), are often 600Hz already due to PWM behavior, and a minor modification to those, combined with new logic in centralized controller, permits 600 frames per second. And I have an algorithm to eliminate zig-zag combing artifacts in panning scenery on concurrent multiscanning.

The great thing is we can mostly forget about discrete LED GtG (unless power-transitor switching is slow) and focus on improving MPRT which is easy to halve simply by doubling refresh rate & frame rate because we already know GtG won't be a bottleneck in MPRT progress on MiniLED/MicroLED/etc. OLED GtG is slower only because of the massive number of tiny microwires reaching tiny transitors, it means that gate switching may be too slow. The light emitting element of the OLED pixel is not the limiting factor, but the difficulty telegraphing a voltage over vast distances over extremely tiny wires in an ultra-brief manner, to get an OLED active matrix transistor switched fast enough.

That's really the only reason for OLED GtG slower than MicroLED/MiniLED GtG -- because panel fabircation of creating tens of thousands of micrometers-wide wires in a modern 4K and 8K LCD panel, it's hard to get electricity from A to B quickly, and even trying to push 10 volts down those matrix microwires (to switch the pixel transistors faster) is like trying to put 5 megavolts into a power transmission corridor -- they'll leak or arc across each other. So you have sweet spot voltage that may switch a transistor a little slower than we want. Nontheless, today's panels (LCD and OLED) are an engineering achievement, even if we bitch and moan about panel imperfections, it's a mircale we pay only $200 for a 24" desktop LCD. I still remember the days when a 3 inch active matric LCD was in the 1980s approached a thousand dollars, before quickly falling to a few hundred dollars in the late 1980s, for portable TVs or airplane cockpits when industry wanted big ultra light weight color displays.

Manufaturing a single LCD or OLED is literally like manufacturing a computer chip these days, with lithography techniques to print millions of transistors onto glass, at integrated circuit densities higher than an Intel 4004 CPU -- across the whole panelglass!!! Some integrated circuits are built into the edges of some modern panels, as part of the same lithography printing -- basically simple ASICs like row-column addressors built into the edges of (some) modern LCDs.

Anyway, kilohertz refresh rates aren't going to be unobtainiumly expensive forever, much as $10,000 4K in 2001 became $299 Walmart specials. There are many cheap-than-expected engineering paths to the true kilohertz display refresh rate over the next 20 years. This engineering stuff much easier than SpaceX Starlink cramming billion dollar phased arrays into a $500 consumer UFO-on-a-stick and is already been done DIY. Do-It-Yourself kilohertz refresh rates (at low resolutions).
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blurfreeCRTGimp
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Re: LPD: Laser Phosphor Display - Successor to CRT?

Post by blurfreeCRTGimp » 27 Oct 2020, 17:17

Hey chief, I read that article about the new OLED method from Stanford and Samsung,with the "introduction of nanopatterned metasurface mirrors,” taking cues from previous research done to develop an ultra-thin solar panel."" I noticed it also increases brightness.

couldn't this process likewise work for MEMS to rid the technology of the dreaded laser speckle (if the surface nanostructure were tuned to accomplish a kind of subsurface scattering?)

Also seems like it could help with the brightness limitations of the technology as well, while cutting power usage. You are the guy with the background knowledge, which is why I am asking.

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Re: LPD: Laser Phosphor Display - Successor to CRT?

Post by blurfreeCRTGimp » 27 Oct 2020, 17:24

ChaosCloud wrote:
26 Oct 2020, 22:36
blurfreeCRTGimp wrote:
23 Oct 2020, 01:19


Based on the article about Stanford's work with Samsung on OLED Using meta surfaces I don't think form factor would be an issue with MEMS for very long. The current projectors you can buy are as small as a wallet.

One of the reasons I have not bought OLED is because of how thin it is. I don't want to spend $1500 on a display that my cat could run into, or jump off of, and snap in half.

I've noticed that consumers change their view when they see a side by side comparison. How many comments do you often see (I see many) where people bitch about needing a sound bar, or bitch about bad sound quality?

Its like "Hey guys, you can either have good sound, or a display as thin as a piece of paper. Your choice."
asus_mitsu2.png

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Re: LPD: Laser Phosphor Display - Successor to CRT?

Post by thatoneguy » 27 Oct 2020, 23:49

Chief Blur Buster wrote:
27 Oct 2020, 14:49

Deliciously fast. But we're still limited via very low pixel refresh rate, but it's actually easier than expected to get kilohertz refresh rates via parllelized scanout logic on MicroLED modules. For example, JumboTron modules (the 32x32 or 64x64 RGB LED metrixes that you can buy off Alibaba or ALIexpress for under $10 each), are often 600Hz already due to PWM behavior, and a minor modification to those, combined with new logic in centralized controller, permits 600 frames per second. And I have an algorithm to eliminate zig-zag combing artifacts in panning scenery on concurrent multiscanning.
I actually have seen quite a few of these for sale in various sites that say they refresh internally at 1920hz.
There's a very interesting video of someone messing around with a higher res 160x120 panel for Game Boy/Game Boy Color gaming.
phpBB [video]


The interesting part I find with these are the round pixels. I know that with circular pixels you lose a lot of brightness but it really does look more organic than square pixels imo.
I wonder if it would be feasible to use them in large screens with MicroLED's sheer brightness. It could potentially help with smoothing out jaggies maybe.

The new Pacman arcade game and Space Invaders Frenzy also use some giant LED screens and look stunning
phpBB [video]

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Re: LPD: Laser Phosphor Display - Successor to CRT?

Post by Chief Blur Buster » 28 Oct 2020, 00:13

thatoneguy wrote:
27 Oct 2020, 23:49
I actually have seen quite a few of these for sale in various sites that say they refresh internally at 1920hz.
And we can buy it for under $10 per module today. But, modification will need to be made to make it 1920 frame refresh (As chips built into the module is designed only for a 60 or 120 frame refresh). To have unique refresh scanouts per refresh, rather than repeating refreshes (e.g. for purposes of PWM controlled brightness, etc).

One can still combine PWM brightness control concurrently with higher unique refresh rate. Given the low-resolutionness of the Jumbotron modules, 32x32 at 1920Hz is only less than 2 millions pixels per second, something achievable on many current buses, though one might need to upgrade SPI to Ethernet, as the module-data delivery mechanism.

Theoretically, it would be no problem to have a stadium sized Jumbotron that is CRT-clarity by running 1920 frames per second at 1920 Hertz;

After replacing the chip built into the back of LED modules, the harder part is inventing the 1920fps high speed television camera. But even, that too, isn't impossible.

1920fps at 1920Hz = creates 1/1920sec MPRT = like 1/1920sec camera shutter speed = ~0.5ms motion blur! The strobeless achievement of CRT motion clarity. A related article is UltraHFR Video: Real Time 240fps, 480fps and 1000fps video on Real Time 240Hz, 480Hz, and 1000Hz Displays. It's well beyond the nausea soap-opera-effect uncanny valley (the majority of SOE headaches is caused by camera shutter being longer than the refresh cycles, because interpolation cannot fix that).

Would be great for playback of sports footage, especially camera-stablized POV footage. And fast camera pans like those that used to be done during the CRT days before they slowed down camera panning to accomodate slow-motion-blurry HDTVs when they first came out.
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Re: LPD: Laser Phosphor Display - Successor to CRT?

Post by thatoneguy » 28 Oct 2020, 00:54

Chief Blur Buster wrote:
28 Oct 2020, 00:13
And fast camera pans like those that used to be done during the CRT days before they slowed down camera panning to accomodate slow-motion-blurry HDTVs when they first came out.
Huh, I never considered that. I noticed how the change in aspect ratio from 4:3 to 16:9 impacted camerawork hugely(and in a bad way imo) but I never noticed the pan thing.

BTW Kevtris says in that video that the 160x120 Panel he has is doing 1Khz and he comments on how smooth the scrolling looks and how there's no refresh artifacts.
Some of the panels I saw on Ebay, Alibaba and other sites also were 64x64 around 1920hz or even higher resolution than that with around the same refresh rate internally.

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Re: LPD: Laser Phosphor Display - Successor to CRT?

Post by ChaosCloud » 28 Oct 2020, 23:17

blurfreeCRTGimp wrote:
27 Oct 2020, 17:17
couldn't this process likewise work for MEMS to rid the technology of the dreaded laser speckle (if the surface nanostructure were tuned to accomplish a kind of subsurface scattering?)
I believe that speckle is an aspect of coherent light. It shouldn't be an issue with invisible UV laser + phosphor as the light coming from phosphor is no longer coherent. Not sure about QD, but from my (limited) understanding of how Quantum Dot works it should also not be an issue.
blurfreeCRTGimp wrote:
23 Oct 2020, 01:19
Based on the article about Stanford's work with Samsung on OLED Using meta surfaces I don't think form factor would be an issue with MEMS for very long. The current projectors you can buy are as small as a wallet.
Sure, the devices can be made extremely small as projectors, but projectors are only useful for dark rooms. A rear-projection set-up makes a projector usable in a lit room, at the expense of space.

There are several kinds of MEMS which are used in projectors. For single beam scanning the type needed is a mirror which tilts in two axes. There is a limit to how far the mirror can tilt. That plus any lens/optics will determine the maximum scanning angle, which we want to maximize in order to reduce the enclosure depth.
STMicroelectronics Blog Image 7.png
STMicroelectronics Blog Image 7.png (128.71 KiB) Viewed 5389 times
The MP-CL1 for example beams at 42.1º (horizontal), which means for a 28" diagonal picture you need 32" throw distance. By my calculation a rear-projection enclosure using a diagonally mounted mirror to reflect the light path (similar to how the RPTVs did it) would be about 12" deep.

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