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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."
The largest problem with this technology isn't that it can't be done on a larger scale (it can). The problem is more financial. With all of these companies having geared up for LCD production and building huge plants while downsizing CRTs, it's unlikely that the shift to LED tech is going to happen anytime soon - no matter how cheap it is.
As always, you have to find a way to pay for the R&D that you use - even if it becomes outdated beforehand.
"...Well, there's egg and bacon; egg sausage and bacon; egg and spam; egg bacon and spam; egg bacon sausage and spam..."
3 years ago you would have spend $2,500 for a LCD of the same quality (if something compareable was even available).
Why do you think that in 3 years people wont look back and say "back than lcds were expensive, a 300$ 20" did cost 1000$ back then...."?
After all, people can make a 19" CRT for 150$, and if you look at the materials and needed manufacturing steps, they arent much simpler than LCDs.
But today, the companys are still paying for their fabs they had to build to supply the increasing demand. Once lcds have replaced crt, demand will stagnate, there wont be any new expensive fabs needed (or at least not as much as now), and prices will be dropping....
HI O WISE PRINCE. WHT TOOK U SO DAM LONG?
It uses an thin organic film between conducting layers rather than electronic components, but OLEDs are just a few years away. They're self-luminous and more efficient than a backlit LCD. Lots of /. stories about them too.
Thats a very important point. I guess LEDs are far from being efficient enough right now. Bear in mind though - energy output from the screen doesn't want to be too high. Comparison in W/m2 - if you used LEDs at normal brightness a screen like that would blind you. I would reduce the current estimate by a factor of 10 or so into the 0.5 - 1 uA range , so about 1 amp per panel. Still a lot compared to LCD, but not if you consider that LCD must also be backlit.
But first LEDs will be used as a backlight source. They are vastly more efficient than the most incandescent sources. The best incandescent lights can achieve an output of 40 lumens/watt and these tend to be halogen lamps, too hot for your lcd panel. Discharge lamps run at 50-60 lumens per watt but the colder versions (fluorescent tubes) produce horrible light. The best white LEDs can produce over 120 lumen/watt; vastly more efficient.
Combined with an infinitely variable colour (within the gamut of the LED) they make an exceptionally good light source, not only for LCDs but also in architectural situations. Already a large number mobile phones and some PDAs use a white LEDs as a backlight source. I'm sure laptop LCDs will be next.
OLEDs provide the next evolution in display technology and hopefully the next jump in efficiency. A black pixel is a very inefficient thing on an LCD panel, think of all that wasted light absorbed into the pixel, much better to be able to switch off the light for that pixel.
(Recapping what some other people have said but I hope I've said something new of note)