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Displays Technology

Toward Micro-Diode Display Panels? 150

Posted by Cliff from the large-two-dimensional-LED-arrays dept.
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."
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Toward Micro-Diode Display Panels? More

Toward Micro-Diode Display Panels?

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  • We need some technology that makes it all CHEAP. Because I spent over $1,000 on a 20" LCD, and although its a kick-ass monitor, its still too pricey.
    • I don't care if the new technology is cheap, as long as it drives down the price of the old. It would be fine with me if something better moved in and made LCD prices go the way of the CRT.
    • Not all that many years ago I paid ~$2000 for a high-end 21" CRT (which probably has less viewable than your 20" flat) - I think we're getting spoiled.

    • Re:Interesting. (Score:5, Insightful)

      by imsabbel ( 611519 ) on Monday December 01, 2003 @08:54PM (#7604869)
      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....
    • polymer led's will be much more cost-effective. once they're in full production, you'll probably start seeing many, many apps utilizing them instead of silicon led's.

  • Being my area of research . . . (Score:4, Funny)

    by nil5 ( 538942 ) on Monday December 01, 2003 @08:42PM (#7604777) Homepage
    I can say that this technology is at LEAST 25 years away due to the lack of precision in nanostructure topology lithographic processes. The author seems to be ignorant of a few of the fundamental laws of nanotech, namely that: 1) Maxwell's equations must be obeyed in light of quantum gravity. Yes, quantum gravity is CRUCIAL to the process. This prevents the inadvertent bonding of junction pairs and 2) The superposition principle does NOT apply to these non-inertial frames of reference! Trust me, this technology is pretty much canned until we can solve a few engineering problems in the litho. area.

    • Re:Being my area of research . . . (Score:4, Interesting)

      by sysopd ( 617656 ) on Monday December 01, 2003 @08:52PM (#7604856)

      I believe new progress in transparent transistor technology could bring many new display types to reality.

      Check out the research [oregonstate.edu] done at OSU. I spoke with several of the research students regarding this technology and it looks promising.

      One of their goals is to make transparent displays like in minority report a reality.

    • Re:Being my area of research . . . (Score:4, Interesting)

      by Anonymous Coward on Monday December 01, 2003 @08:58PM (#7604897)
      Are you on crack, or just a troll?

      The Planck scale, which is likely to be the energy scale of quantum gravity, is around 10^17 times bigger than the weak scale (where we live).

      Gravitational effects won't even come into physics at the LHC (unless large extra dimensions a la Arkani-Hamed et al exist -- and they probably don't).

      Quantum gravity has bugger all to do with nanotech, or indeed, anything which is likely to exist in the near future...

    • It's my area of research . . . (Score:5, Informative)

      by feyhunde ( 700477 ) on Monday December 01, 2003 @09:17PM (#7605018)
      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.
      • The original poster was referring to silicon LEDs. These can be produced on a silicon wafer using bulk processes - eg. you can create an arbitrary amount of LEDs.

        ST is in the process of commercialising their silicon-LEDs. Their first product will be a fully integrated opto-coupler.

        Unfortunately other applications are still way off. A display would require far more brightness than the device is able to deliver, not to speak of different colors. Their efficiency is low, so heat may be a question. Also yield
      • I think you've pretty much guaranteed that inorganic LED technology will now prevail, thanks to the fact that "It's impossible." :)

  • Wanna play? Gotta pay! (Score:4, Insightful)

    by Chordonblue ( 585047 ) on Monday December 01, 2003 @08:46PM (#7604807) Journal
    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.

    • This comment doesn't make sense. What you're saying violates the most basic law of economics for businesses: do not take sunk costs into account.

      Anyway, your reasoning is clearly fallacious:

      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.

      You mean that even if it cost $1 to build an LED plant, they would still stick with LCD plants just

      • I'm sorry, I assumed most readers would use common sense first before posting.

        1 Cent, huh? Give me a break. No major tech change like this will ever be funded at a break-even point. No, they will LOSE money to go to this.

        Note that I didn't say that the price would ultimately be cheaper - I think it will. But saying that and having become reality are two different things.

        For instance, they still haven't solved the blue LED longevity problem - one of many things that need R&D. You know, Research and De
      • ChordonBlue:
        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.

        soundsop:
        This comment doesn't make sense. What you're saying violates the most basic law of economics for businesses: do not take sunk costs into account.

        Well, it makes a limited amount of sense. If I am considering making these hypothetical LED displays, I need to assure myself t
        • What you say basically proves parent's point that you only need to take into account the marginal costs of making one LCD screen vs. one micro-diode screen, not capex of building the LCD production plants.
    • Check this [yahoo.com] out. Highlights (emphasis mine):

      The cost of the $13 million, four-year project will be shared among NIST, GE and ECD Ovonics. The program goal is to create a cost-effective system for the mass production of products such as flexible electronic paper displays, portable TV screens the size of posters, embedded sensors, solar powered cells and high-efficiency lighting devices.

      It isn't because it can't be done. It is because the Veruca Salt money managers on Wall Street can't tolerate a four ye
      • Exactly correct. But there are still production hurdles to overcome. Wall Street seems clueless about a lot of tech things (like the future of SCO for instance), but they do understand reasonable risk.

        When these display companies have sunk billions into R&D and plants already, the last thing they want to do is risk what they've already done.

        No one wants to be the first to do it, and yet, that company will probably end up leading the revolution (when it finally comes)...

  • Paper-white reflective would be better (Score:5, Interesting)

    by caseih ( 160668 ) on Monday December 01, 2003 @08:47PM (#7604820)
    I think we're barking up the wrong tree using light-emitting technology for displays. I think that we would be far better off having a very high-res, paper-white display that was 100% reflective. Indeed others have called this "digital paper" and it has become a holy grail of display technologies. However the technology to do this is just about here now. I'd much rather see that kind of display. Give me a reflective, 600 dpi display and then I'll read books on a computer. Light-emitting displays are much harder on my eyes than a magazine or newspaper.

    • Sure, for black and white (Score:4, Informative)

      by brunes69 ( 86786 ) <[slashdot] [at] [keirstead.org]> on Monday December 01, 2003 @09:01PM (#7604925)

      Reflection based displays, like eInk [eink.com], 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.

      • Re:Sure, for black and white (Score:1, Informative)

        by Anonymous Coward
        Actually the US Military already has MEMS reflective color displays based on diffraction by tiny mirrors with piezoelectrically controlled separation.

        • Re:Sure, for black and white (Score:5, Informative)

          by Anonymous Coward on Monday December 01, 2003 @09:13PM (#7605003)
          That is actually true [iridigm.com], BTW.

          • Interesting concept. But I'd guess they will have serious yield problems. Also it is probably pretty difficult to extend this operation principle to flexible paper like display, as it relies on a mechanical effect.
            • Also it is probably pretty difficult to extend this operation principle to flexible paper like display, as it relies on a mechanical effect.

              According to the website:
              • A display using their technology would be thinner than a LCD screen.
              • They're investigating plastic substrates. (the manufacturing process uses lower temperatures than LCD fabrication.)
              • It's using MEMS (= Micro Electro-Mechanical System) devices. These are small enough not to break off from a bended substrate (if you succeed in putting them o
              • It's using MEMS (= Micro Electro-Mechanical System) devices. These are small enough not to break off from a bended substrate (if you succeed in putting them on it).

                MEMS does not mean it provides solutions to anything.

                RTF Website

                Well, in fact I did. Actually I am into the field of MEMS, therefore I am trying to look behind the marketing statements. And, from my perspective these devices look like they are very sensitive to differential stress which occurs during bending.
      • 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.

        The operating principle of a full color e-ink display is the same as that of a grey scale one. You just need colored pigments/filters. Its merely an issue of manufacturing, but not a limit of the technology. This is being worked on...

    • Yeah, I would really like to try to play games or do anything at night - holding a flashlight in one hand!

      Seriously, uniform lighting and color are a necessity for a decent display (at least in terms of laptops). There is no way you would get one from a paper-white display.
    • But then they can't control your brain waves! Sheesh.
      ---

      I would kill for a reflective display, a nice matte, soft screen to look at. I would never leave my computer.
    • A couple things:

      One of the premises of this post is wrong: LEDs do not currently come in all colors. It's easy to think they do, though, as those keychain lights come in various colors to serve the candy raver community. Those are still, however, mostly red and yellow LEDs with colored filters on them.
      In order to have an accurate display, you're going to need white LEDs, which have only just been produced in university labs and won't be ready for mass marketing for quite some time.

      And in order to ha
    • This is absurd,

      Light based displays are not hard on your eyes, default full throttle all white backgrounds are hard on your eyes. - Like Slashdot.

      Reflective surfaces have some interesting properties - for example, they tend to autoadjust to the ambient light levels and color - thus always appearing neutral in color and density. - This could be a property of emmitor displays.

      In the end - LEDS have a potential for the least power consumption - because no back - or ambient light source is required. However,
    • I can watch my computer without needed an extra desk-top. I believe that a refractive or reflective display would require an external light source?
  • Neither is to the point of making that concept practical.

    Unless you got an extra 10grand to spend on a 5" screen that needs a small nuclear power plant to run..

    ( ok a slight exaggeration, but you get the point )

    They would be pretty thou..
  • Any time, as soon as the costs goes down to a manageable level, and the light level remains consistent throughout the display.

  • OLED (Score:2, Informative)

    by ArkiMage ( 578981 )
    Just keep getting OLED displays larger and larger...

    http://www.kodak.com/US/en/corp/display/

  • OLEDs (Score:5, Insightful)

    by homer_ca ( 144738 ) on Monday December 01, 2003 @08:57PM (#7604889)
    It uses an thin organic film between conducting layers rather than electronic components, but OLEDs [kodak.com] are just a few years away. They're self-luminous and more efficient than a backlit LCD. Lots of /. stories [slashdot.org] about them too.

    • Re:OLEDs (Score:5, Informative)

      by deglr6328 ( 150198 ) on Monday December 01, 2003 @09:04PM (#7604944)
      I'd like to point out that anyone interested in OLEDS may like to have a look [universaldisplay.com] 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.
      • Impressive. Is it possible for OLEDs to have an off value so that they are transparent? That would be most useful in using things like HUDs in airplane helmets and such.
        • Doubt it. The power-supply must be somewhere. It happents it is at the backside of the OLEDS and not in front of them, as nobody could see any pixels then. ;) Takes much room.

          Meaning: The transparency may be achieved if the pixels are big enough, but then the resolution would suffer.

        • Re:OLEDs (Score:4, Informative)

          by homer_ca ( 144738 ) on Monday December 01, 2003 @09:33PM (#7605121)
          Sure it's possible. The linked site has a page on transparent OLEDs [universaldisplay.com] too.
          • Interesting. It says they can be top-emitting, bottom-emitting, or both ways.

            I wonder if you can still see through them from the side they are not emitting to? That would make for some interesting designs in eyewear =)

            Very cool techology. The future is almost here =)
    • The last time I posted about OLED I was informed that the holdup on this LCD-killer is the fact that the blue component fades out very quickly; within a year or so.

      Once that problem's solved, it's only a matter of time before I'll be able to cover my walls, and ceiling with the stuff for a year round aquarium/planetarium/landscape/cloudscape/harem. :)

      --

      • I've understood this to be the excuse as well, but one of the big promises of OLEDs was supposed to be that they can be made very cheaply.

        So I ask, why don't they just put the OLED display into an easy-to-swap module and let us buy a new one for a few bucks every six months or so (like batteries)?
    • I thought OLED was already being used now, mostly in car radio displays. I think the only difficulty is getting the color range that people are now used to getting from a computer display.

      Given that it is organic, how long will they last?
      • Given that it is organic, how long will they last?

        When you hear the word organic, think 'made from carbon' not 'made from animals'.

        In the OLED case, plastic would probably be more straightforward term than organic, but I guess plastic sounds too cheap.
      • >Given that it is organic, how long will they last?

        I believe I've read that moisture is a big problem with current OLEDs...small amounts of moisture ruins them rather quickly. The hope is that researchers will come up with a more moisture-tolerant version.
  • To be a useful technology (ie. cost and lifetime) for displays the pixels need to have a very high yield and reliability. I wonder whether LED is sufficiently high yield to work?

    It does seem to me though that using silicon LEDs (ie. enough silicon wafer to coer a display) could get pricey.

  • LEDs are not cheap (Score:5, Informative)

    by Rosco P. Coltrane ( 209368 ) on Monday December 01, 2003 @08:57PM (#7604892)
    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.
    • The only large LED display I've seen up close used quads of

      Red Blue
      Green Red

      • Really? All the ones I've seen are RGBG, presumably because the eye is most sensative to green (which is also why 16 bit color is usualy r:5 g:6 b:5)
        • You're probably right. It was a few months ago. I was mostly suprised by the groups of 4. It was a large outdoor display probably 10' x 10' made of 25 , 2' x 2' panels that had some huge power chords going in the sides.


          Floating eye corpse?

        • So is that why the reds on my DVDs are so poor? I always felt they weren't allocating enough for gradations of red in displays, and heard that we were most sensitive to red because of the need to identify blood (our own as well as of others).

          And also why they use red for stop lights (and tail lights), which are far more important to notice than green.

          And this web page [uc.edu] seems to indicate that the red sensitivity is broader than that of green.
    • 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.

      Minor detail.... you have listed colors in order from highest to lowest frequency.

    • Manufacturers have had the capability for a few years now to fabricate LEDs with a peak at any visible wavelength. These peaks are sharper than the peaks of most CRT phosphors.

  • We're almost there, actually (Score:4, Interesting)

    by beefstu01 ( 520880 ) on Monday December 01, 2003 @08:57PM (#7604893)
    ...But not with Silicon. Silicon LED's may be (relatively) cheap for red and green models, but the blue ones are insanely hard to make, and thus are quite pricy (just look at the DigiKey catalogue). Also, Si LED's are very ineffecient (I don't remember the number, but it's like 20%ish I thought). The next "wave" of things are going to come from OLEDs (Organic Light Emitting Diodes). These are easier and chaper to make for screens and such, and eventually can be made in a "roll to roll" production type deal since these things are "grown." They're already being used in some cell phones, I believe.

    A problem with these is that they decay if they're not protected, so currently they use a glass-substrate and a glass coating for some, which can make them bulky. Also, OLEDs have a shorter life span than LCD's, but that's being worked on too. So hark, have patience, OLED screens are coming. Another interesting technology to look into is Light Emitting Quantum Dots... those little suckers are cool, and could also replace LCDs and lights as we know it (from what I remember, they're also quite efficient... I think around 60%).

  • Problem: delivering current into the array (Score:4, Informative)

    by G4from128k ( 686170 ) on Monday December 01, 2003 @08:59PM (#7604905)
    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.

    • Re:Problem: delivering current into the array (Score:2, Insightful)

      by Anonymous Coward
      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.
    • Getting the current into the array is probably not an issue, there are plenty of CMP metal processes that can provide the multi-layer interconnect paths. I have designed IC's with 1-3 amps of current on them as a matter of course. The thermal issue seems much more of an issue than the actual currents, also the high current array drivers, and the ballasting of diodes for current balance. A thermal nightmare. The big commercial displays are already a sea of coolong fans to keep them alive. However, the cost
  • [dow.com]

    some new tech
  • I hope this will lead to flat panel displays that aren't so touch sensitive cause cleaning my LCD is a pain when crud gets stuck to it, also i would imigine this could lead to shaped displays and eventually being able to skin devices such as cell phones rather than buying a cell phone faceplate just downloading a cool design and being able to switch designs like ringtones (and even being able to photoshop your own designs) I'm waiting untill i can have a winamp vis that will animate my entire Case

  • Current (Score:3, Interesting)

    by HarveyBirdman ( 627248 ) on Monday December 01, 2003 @09:21PM (#7605040) Journal
    You have red LEDs down around 2 mA in some extreme cases, but the blues still require something close to 35mA. Greens are generally more than reds, but they have them at the 5mA point, I think.

    So you need a red, green and blue to make one pixel just like a phospher display, and the circuitry to provide a precise analog current to all three LED chips and every pixel. And you have to avoid crosstalk between pixels.

    Still, I use blue LEDs on my front panels a lot as simple indicators. They am kool. :-)

    • Re:Current (Score:2, Interesting)

      by Anonymous Coward
      Are you fucking kidding man? Have you actually ever driven a high efficiency blue LED at 35mA, or even 2mA? Do you know how bright those get?

      We can do a lot better than running each pixel at it's max forward current rating.
  • I know that I have wondered about making a large display with LED's.

    My thought was to build it with a standard block sections, then you just use the number of blocks to create your screen size.
  • I have a small keychain light that uses an LED. It's like this one [hikepa.com] but probably a slightly different design. I've had it for about a year now, and it's gotten at least a week's worth of powerful light out by now, with no sign of quitting; though I admit I haven't abused the thing as much as that guy.

    If you google around the web, you'll see that LEDs are poised to become the primary source [gsu.edu] of lighting in coming years; they already last longer and can produce powerful lighting more easily than bulbs, so all

  • Nanotube based Field Emission Displays (Score:3, Interesting)

    by davegust ( 624570 ) <gustafson@ieee.org> on Monday December 01, 2003 @09:35PM (#7605135)
    These devices are a more natural successor to the CRT based systems - excellect contrast and brightness (as good as existing CRTs), flat panel design, lower power consumption (as compared to plasma). The technology is essentially one cathode per pixel.

    From IEEE Spectrum, September 2003:

    Samsung and Motorola are aggressively pursuing field-emission display technology using nanotubes. Samsung, for example, has already demonstrated a full-color 38-inch field-emission display capable of handling normal video frame rates. What's more, a Japanese government-funded consortium was announced earlier this year to develop similar displays, and Sony Corp. (Tokyo) is developing its own nanotube display technology as well.

  • OSRAM MultiLED for 17" Displays (Score:4, Informative)

    by LuckyStarr ( 12445 ) on Monday December 01, 2003 @09:39PM (#7605179)
    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

  • why they dont do it (Score:4, Interesting)

    by WillRobinson ( 159226 ) on Monday December 01, 2003 @09:42PM (#7605202) Journal
    First, each led must have a wire on it. This limits the led to the size, that a ball will fit on. This is usually about 25 microns. (approx 1 mill)

    So now the led must be bigger than that, so now you would have a die, normally around 10 mills, to be nice and bright. Now space them out with say 7 mills in between, and do an array, with perfect dimensions between die, (remember, you have to have a spacing big enough to place the wire down to the pcb, and you will end up with a spacing of around 17 mill centers or so.

    So you see, the pitch is rather large, then you add some optics, so you can make the whole thing look good, and a 1024 x 768 to be pretty clear.

    Then throw in some optics to change the view, to a smaller pitch, and walla you have the viewing scope used on so many tanks ;)

    This has been built for along time, and is VERY expensive.


  • LEDs take way too much power to be effective for displays.
  • Are organic-LED based projectors a viable future direction? I have an NEC DLP unit - which is nice and all, cost around $2000 and is rated 2000l (and a 20' LCD screen). Both of course would have cost far more three years ago (and the projector replaced a Barco 1208s CRT model - at 180lbs these things were no joke, especially in a club...) - but both seem to be near the limit of the current technologies. Or will nanoscale micromirror devices allow for increased resolution and decreased response time (and may

  • I have no doubt LED based displays will come (Score:3, Insightful)

    by gsdali ( 707124 ) on Tuesday December 02, 2003 @04:18AM (#7607248)
    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)
  • Damn, this is one of those posts that makes me wish articles could be moderated (not to affect their visibility, but... for something :P ). Kudos to Cliff for giving so many links which were not only totally relevant but actually specific and technical. Some posts link to just one article that is so sweepingly general I get a headache.

    This is News for Nerds [TM].

  • THANK YOU, ALL (Score:3, Interesting)

    by VernonNemitz ( 581327 ) on Tuesday December 02, 2003 @10:13AM (#7608345) Journal
    Thanks for all the responses!

    I should mention that it has been my understanding (perhaps mistaken) that OLEDs are not actually diodes, but "devices", based on electroluminescent phenomena.

    I confess I posted the Question mostly out of curiosity: the technology SEEMS so obvious....

    I personally agree that reflective-light display technology is potentially inherently superior. My personal favorite (so far) can be found here [iridigm.com].

  • Not directly related to display panels, but since we're talking about LEDs here, something I've been curious about...

    A few years ago LEDs were these dim little lights that might come on to tell you that your hard drive is being accessed or your caps lock is on. Lately we see products like LED traffic lights, LED brake lights on cars, LED flashlights , etc. that are vastly brighter than the old LEDs we've seen for years. What sort of breakthrough or advances did the LED industry make to allow such bright,

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