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As far as I can tell, most "e-paper" has focused on two technologies -- the original 'white side/black side' rotating-sphere design, where the little balls or molecules flip one way or the other based on charge, and Philips' new oily-dye tech for color displays, where oil dyes ebb and flow across pixels for similar reasons.

There's OLED and FED and LCD and all that, but 'e-paper' seems to imply a non-emissive display meant for reflective viewing, with no backlighting, and theoretically reduced power consumption to make it worthwhile.

If I'm following this right, these guys, with their 'NCD' stuff, seem to have found a way to make that sort of display with a higher resolution and faster response time, using more of an LCD-like substrate (so we're talking fragile glass panels with electrodes, but at least we as a species know how to do that). Instead of spinning physical spheres (be they balls or large molecules), or getting macroscopic globs of dye to slide around, they've found a repeatable and reversible electrochemical reaction that'll turn their coating from 'invisible' to 'colored' and back again, as those little molecules change the absorption/reflection of the substance depending where they're bound. Upshot is that it looks good, offers another possibility for color, and miiight be more stable against sunlight bleaching... downside is that you still need one pixel with one cocktail per color.

This seems like a halfway step between existing e-paper and what Iridigm were working on, where you're basically using microprisms to refract the spectrum of light you want... but the Iridigm tech requires a lot of (admittedly elegant) complexity, since each infinitely-variable pixel has to be made up of a ton of microactuators of one form or another. Upshot is that Iridigm would guarantee stability in sunlight (as long as heat doesn't fry the circuitry itself), since there are no chemical dyes or filters to 'wash out' in the classical sense... But does the NCD stuff offer any new breakthroughs in stability?

(Not whoring for Iridigm, they're just the only new display tech I've never heard anyone else talking about.)

The answer is just around the corner: optical interference displays (OIDs). They produce far sharper and brighter images than an LCD. The OID also consumes less power than an LCD.

I wouldn't expect them to be very cheap at all though, Iridigm is the only company that makes them. Well, Qualcomm soon if you read that latest press release.

Possibly around the corner for phones, I'm not holding my breath for anything bigger. It does sound like neat tech though.

What's certain, according to her, is that even though Genoa's technology increases the range of colors, it's not recovering the full original color information of a movie on film, lost in the conversion to other formats, like DVD. "It's kind of arbitrarily making images look better," she says, though people will in fact prefer the resulting colors, which will typically be more saturated and brighter.

Various video media may not have the necessary color resolution to drive these displays, but (given quality art assets;) newer video cards do.

I wonder how these types of displays compare to Iridigm's upcoming products on color fidelity. Those look quite interesting, especially at effective 200 DPI.

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.

That is actually true, BTW.

2048x1152 DLP (front projection)
1280x720 DLP (rear projection)
Flat CRT (still under development)
Inorganic Electroluminescent (still under development)
Electrostatics & Suspension (ambient light, still working on color)
Electrostatics & Revolution (ambient light, still working on color)
Electrostatics & Interference (ambient light, no plans for larger modules!?!?)

There's another interesting technology at Iridigm.

No, quite the opposite. LEPs/OLEDs are an emissive technology - they simply emit light, so they work just like tiny, plastic light bulbs. Power consumed is relative only to brightness.

As for people concerned about iMoD power consumption, check the Benefits part of the web site. Holding a still image, they consume almost no power - a tiny fraction (1/10 or less) of what a reflective LCD does. Doing full-motion video, they still consume 1/3 - 1/4 that of a reflective color LCD. (Reflective color LCDs are used in some PDAs and phones - very different from desktop or laptop LCDs.) This is comparing them with no backlights (sidelights, actually), so it is apples-to-apples.

And since iMoD is 3x brighter, (3x more reflective, actually,) it can be used in much darker environments with no back/side-lighting, which has obvious power benefits for mobile devices. LEPs/OLEDs, meanwhile, don't reflect light at all - they only emit light - so they inherently use many, many times more power.

From the site: "iMoD elements are minuscule, typically 25-60 microns on a side (400-1,000 dots per inch). Therefore, many iMoD elements are ganged and driven together as a pixel, or sub-pixel in a color display. "

So intensity is a function of the ratio of active vs total elements per pixel

They must have some sort of lighting in mind. According to this graph, power required for a legible display increases as the ambient light goes away. The simple explanation is "someone is turning on a light". But their site doesn't give any details. Side-lighting, maybe?

Well, the Economist article reproduced on the Iridigm website indirectly answers this question.

Iridigm's technology, which it calls an interferometric modulator, or I-mod, works by fine-tuning the gap between reflective surfaces. I-mod pixels (the dots that make up the display) are tiny paired mirrors, and the distance between these mirrors can be adjusted to one of four settings. Three of these settings correspond to the primary colours red, green and blue, from which all other colours can be constructed. The fourth is "closed", which means that no light can be reflected, and so the pixel, and thus that part of the image, is black.

Apparently, they'll be generating all colors (including white) by using RGB (plus black) combinations

The distance moved is going to be on the order of the wavelength of light - 100 nanometers or so. In fact, this slide pretty much says so - less than a micron.

But what does that say about time ? I don't think there is a real concern. As long as one of these babies can flip in less than 10 milliseconds (and it surely can), there will be no issue wrt speed. In fact, it can very likely be a LOT LOT faster than a CRT, because you merely need to change voltages on transistors, whereas a CRT has a scanning beam that has to traverse the whole screen.

The other thing I found REALLY interesting is that such a display could be run native in a HSB (hue-saturation-brightness) mode. Instead of three colors, each pixel could be ANY hue, since you only have to change a voltage to a new value to change the color. Way cool (they are planning initially for full RGB compat). But in the future it could be a new sort of color scheme entirely.

Of course, it's all vaporware until there are production models.

Looks like they might be giving up some of the lower voltage benefits in order to get higher pixel density. Hence their claims about glossy magazine appearance?

Check here

They have a Palm display side-by-side with display with their technology. (it's b&w) you canhardly see any individual pixels on their screen. Text is rather crisp, almost printed.

They claim that since the entire display is inorganic, it's insensitive to temperature variations. Looks like the marketing folks have gone a bit too far on this one. Metal and glass have very different coefficients of thermal expansion. That suggests that the metal layer will be under tension at cold temperatures and under compression at high temperatures. This should affect the interference layer thickness achieved at a particular voltage. I expect that this will, at the very least, affect the display colors since interference wavelength is very sensitive to the thickness of the interference layer.

Anyone care to do the math?

If you'd care to look a Iridigm's website, specifically the bit about power usage, that does not seem to be the case. They give power usage for "video imagery".

Granted, they don't give a lot of detail, and the graph doesn't even have a scale... but they claim that the technology uses little power even with moving images, and there is no basis to dispute that at this time.

I would have a tough time believing that it uses more power than a CRT. Even if it does use substantially more power than they claim, it would still be well within laptop territory.

How do they get color graduations? If the plates are bistable, how do they get more than 8 colors (with each of red, green, and blue being either on or off)? Or can they make the plates hover in-between stable states by applying a current?

They claim years of operation. Of course, this is marketing literature.

It needs a front light but only in dark environments. Apparently, the reflectivity of the surface is sufficient for normal lighted environments

If you actually look through their site, it looks like they are aiming for the PDA market, not the desktop display. Perhaps a limitation of the technology, perhaps a really good understanding of the strengths and weaknesses of their product.

Interesting that the site spouts off on touch screen technology. I've always loved the spontaneous change of LCD to LSD when you press on you LCD pannel, with these, you might just semi-permenantly change the pixel!

And they are showing progress, definitely beyond the "vaporware" that some commentors have said. It appears that they *have* a working product that they demo'ed in May of 2000.

Iridigm Demonstrates First Color iMoD Matrix(TM) Display
SAN FRANCISCO, Calif. - May 20, 2002 - - Iridigm(TM) Display Corporation, a developer of flat panel displays for mobile devices, will demonstrate its iMoD Matrix(TM) technology at the Society for Information Display (SID) International Symposium in Boston, Massachusetts. During the Exhibition portion of the conference held May 21-23, 2002, Iridigm will demonstrate the color iMoD Matrix(TM) display in its booth #1805/1807. This is world's first direct-view color flat panel display based on MEMS (Micro-Electro-Mechanical-Systems).

Continued here

Fast response allows artifact-free video and gaming.

Now they don't seems to have any data on framerate you can achieve or power consumption when the complete screen is refreshed frequently.

The company's website reports microsecond response times for their iMOD elements. Ten microseconds would support 100 FPS, which should be fine for gaming (isn't TV interlaced 50 FPS?)

Actually, the hysteresis in the MEMS position suggests that a residual image might be maintained if power is lost. It just won't retain the original colors.

This technology is great for displaying text (and pictures of butterflies) but it is very bad for games.

Look at the description of how it works. The colour is determined by the distance between glass layer and the metal plate. Big gap = red. Small gap = blue.

This is fine for static images, but it means that it takes 5 times as long for a red pixel to change state as it does a blue one.

When you have a quickly moving image, the result in severe ghosting for red objects. White objects will leave a rainbow trail - red at the far end, blue near the object. Blue objects are relatively unaffected.

If you do use this for playing Quake 3, just make sure you're on the blue team.