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Toward Micro-Diode Display Panels?
VernonNemitz asks: "Light-Emitting Diodes (LEDs) have been around for decades, and they come in all colors. Here are the basic principles behind their operation, information on what's currently in production , and other practical info. Now, you would think it obvious that video displays should be made from LEDs, to take on the various competitors. Certainly this has been done on a large scale, and I am not the first to be interested in LED display technology for home viewing. The apparent goal of silicon LEDs these days seems to be tied up with optical communications between circuits, have they forgotten the possibility of making high-resolution display panels?"
"Achieving a good image will require smaller pixels, and now I have a better understanding of what has been holding it up, so would like to share what I found out. Basically, unlike a lot of electronic technology, LEDs are mostly -not- made from silicon. So, while silicon diodes are common, and large arrays of them are also made (for sensors), LEDs are not easy to incorporate into standard integrated-circuit manufacturing. Nevertheless, researchers have been pursuing and steadily making progress toward integrating silicon-based LEDs. Even whole arrays, 'suitable for large two-dimensional areas', of silicon laser LEDs have been made, as far back as three years ago."
Just keep getting OLED displays larger and larger...
http://www.kodak.com/US/en/corp/display/
Red leds have been around for decades, but the higher you go in frequency (orange, yellow, green, and recently blue), the more expensive they get. Since you need many many triads of them to make a display, that may not be the cheapest one in town.
What's more, more often than not, LED colors aren't pure primitive colors, so it's even harder to get accurate RGB mixing with them.
"A door is what a dog is perpetually on the wrong side of" - Ogden Nash
I suspect that the technical limitation is that of delivering enough current across the span of the array. Unlike plasma displays, LEDs are low voltage beasties. And unlike LCDs, LEDs are high current devices. To get say 20 W of brightness, you will need to inject on the order of 10 Amps in (and that 10 Amps only gives you 11 microamps per LED in a 640 x 480 x 3 color display). Routing that much current along the array conductors(which are probably plated or grown on the glass substrate) with acceptably small voltage losses would seem to be very tricky.
That's just my guess as to the technical hurdles for high resolution LED displays. I'm sure some bright young soul will solve the problem, however.
Two wrongs don't make a right, but three lefts do.
some new tech
Reflection based displays, like eInk, are great for displaying text. But when it comes to representing graphical concepts they fall far short, since they're limited to greyscale.
It's fairly simple to adjust the amount of light reflected to make greyscale images. What is very hard to do is adjust the wavelengths reflected to make different colors. Until there is an easy way to do that discovered, light emitting displays is pretty much the only option for computing chores that rely on color.
I'd like to point out that anyone interested in OLEDS may like to have a look at what they are really capable of. A year or so ago I saw a ~9 inch (diagonal) demo of a Kodak OLED and it was nothing short of AMAZING!!! The contrast ratio was extremely high (very black darks and bright areas right next to eachother), color saturation was great(far better than any LCD I've ever seen), switching time was super short (MICROseconds) so there is no blurring and the whole thing was no more than 2mm thick.
- "Hear that?! The percolations are imminent! Cease your ingress!"
I have experience in the industry, and can tell you that inorganic LEDs HD displays are not gonna happen. The inorganic LEDs cannot be deposited on silicon wafers. The inability to deposit means no way can it be cheap, or feasible. Not to mention the heat output by that many LEDs. I created a test box to evaluate LED's for lighting systems. Using the latest mass produced ones, I still had a significant heat output with 100 tiny ones. A HD inorganic LED panel would simply melt. Organic LEDs remain viable, yet still not ready. OLEDs can be deposited and can use much of the same wafer design. They have many issues, most dealing with lifetime and color shifting, but it works for HD. Kodak is spending a lot of effort on the technology, and I was allowed to use two of the OLED displays and gotta say they have a good design, but just need more help in the material science.
I'd say more, but my guild is raiding.
Sure it's possible. The linked site has a page on transparent OLEDs too.
Just found something... OSRAM is producing a
LED-Package not to form a display as itself, but
rather a backlight for common displays (presumably
LCD, but they say nothing about it specifically).
The good thing they say is, that the colour
temperature can be adjusted with that technique.
As far as I am informed this is not the case with
current LCDs? Or am I wrong?
Could be somewhat in between the both technologies.
Sort of bringing "the best of both worlds" together.
Link to the Osram Website:
http://www.osram-os.com/news/news_multiled.html
Meme of the day: I browse "Disable Sigs: Checked". So should you.
> The best white LEDs can produce over 120 lumen/watt; vastly more efficient.
That doesn't sound right. I believe that Lumiled's Luxeon III LEDs have the highest luminous output at 80 lumens at 1000mA maximum flux.