Paper Capable Of Playing Videos Developed

Makarand writes "Nature has posted an article describing paper capable of displaying video using rearrangeable electronic ink, being produced by Philips Research Labs (in the Netherlands). The paper-display draws power from a lightweight battery, and displays data stored in a portable chip. The display consists of pixels containing a drop of colored ink that can spread over a reflective white background under electrical control to create colors. With fast switching times and lower switching voltages, these paper-displays are capable of displaying video images."

Comments

BBC News story...

[WIAKywbfatw]

Here's the BBC's slant on the news: Electronic paper prepares for video.

They're already up to 80 Hz refresh (12-13 ms respnose times). That's pretty damn impressive for a technology that's still in the basic R&D stage, and it augurs well for the future.

Re:BBC News story...

[dmoynihan]

Bistable nematic screens can do 25 hz--difference is they're shipping it out right now.

But how do you get color?

[panurge]

The picture in the article has to be misleading. Although a camera has adjacent color receptor sites, print color doesn't work like that at all. If the cells are adjacent, they can only produce an approximate gray. In the CMYK standard printing process, the ink markings superimpose, so grays are achieved with different sizes of black dots, and red is obtained by superimposing yellow (-blue) and magenta (-green). This means that instead of being adjacent as in the picture, the cells would have to be stacked. There would also need to be some way of ensuring that when the cells were partially colored, the upper colored areas were not directly over the ones below (or they would be obscured and only the top color would show.)

There may be some magical solution to this, but it looks to me as if color is very, very much more difficult than mono.

Re:But how do you get color?

[MalachiConstant]

In the CMYK standard printing process, the ink markings superimpose, so grays are achieved with different sizes of black dots, and red is obtained by superimposing yellow (-blue) and magenta (-green). This means that instead of being adjacent as in the picture, the cells would have to be stacked.

I worked in a pre-press shop for a couple of years, so I've worked with printing on a very low level. The color dots don't need to be directly stacked on one another to achieve a certain color. In fact each color is printed at a seperate angle so the dots are rarely directly on top of one another

Take a magnifying glass to your sunday comics and you can see that the black dots are at one angle (usually straight up and down) and each other color is rotated slightly. Even at relatively large dot sizes (72 dpi) the dots seem to merge together to form whatever color they're looking for.

Since the dots are arranged in groups of four in this paper you could achieve the same result, except it may look a bit more like a computer image (made up of distinct pixels in a grid) as opposed to a magazine picture (pixels for each color are rotated). It also sounds like they can make the dots whatever size they want, which is how it is done in printing:

The larger the applied voltage, the more the ink retracts. The ink is therefore capable of a continuous grey scale, not just of a two-tone contrast.

And even if the dots were stacked directly on top of each other it would still work. The ink is spread so thin that it's transparent, that's why yellow on top of magenta shows as red. So if they could stack it somehow it would show correctly (assuming the ink they use is like regular ink in that way).

Re:But how do you get color?

[pVoid]

Hmmm, the painter Georges Seurat was a pointilist. I'm not going to post a link to his picture because we would melt down any server I link, but a quick google for his name will find you pictures.

My point is: if you look closely at those paintings, the dots aren't superimposed. They are side by side. And they are quite big: the size of small brushes... So it *does* work.

Re:But how do you get color?

[MalachiConstant]

Here's an image showing a close-up of a CMYK image.

(And if I remember correctly black is actually printed at 45 degrees, not straight up and down like I said)

Re:But how do you get color?

[AlecC]

It is not a question of working differently at a molecular level. In the thin film that actually ends up on the page, the inks are translucent - think Jello, not paint. Each ink absorbs the light at some frequencise and passes others, which then bounce of the white paper behind - unsess abosrbewd by another ink at the same point. It is not perfect, and in bulk the inks look opaque. But the inks are actually printed over each other.

You are right that, if the dots are really small, the eye will average them out. This is, actually, how screen printing works: there are actually rows of dots in shaded areas. However, they are of the order of 30 times smaller than pixels on even the best screen, so it takes quite a powerfule glass to see them.

What the article doesn't say, but the picture does, is that Cyan+Magenta+Yellow, which should theoretically produce black, actually produces a durty purplish brown. So you need some real black to get a good rendition. Each pixel will have to have four cells.

Grandparent is correct. Because the cells are spatially separate, 100% red will actually only have 25% of the the background red, the rest remaining white. So I would expect a colour display, while having good readability, to be rather flat an uninteresting. The B/W display should be very good. Because it is reflective not emissive technology, it should have excellent readabilty and low poer consumption (but not the zero power consumption of the e-Ink in /. a coupel of weeks ago).

Basics of television technology

[Anonymous Coward]

I guess that depends on what you mean by a "great" frequency. In Europe, television has a frequency of 50Hz (it's 60Hz in the US) - even if I've heard that two and two frames are alike, in other words that the frequency is 25 or 30Hz. Movies in theaters are usually run at 24 frames per second, in other words a frequency of 24Hz.

The 50/60 Hz number is for fields per second. As you might know, (standard) television is interlaced; one field has the the odd lines of the picture and the other has the even lines.

If the source material was video, which stores its pictures in fields, you can see this in fast-moving objects (there's a ripping effect; occasionally you can see this effect in badly encoded DVDs also). Video source material is used mostly in documentaries, news, etc.

If the source material is film (most TV series are shot on film, as are all movies ;-) then you have 24 FRAMES (not fields) from which to construct your 50/60 fields per second. In this case, adjacent fields do come from the same picture, and effective frame rate is 24 Hz.

(If you have 60 Hz TV, the method is called 3:2 pulldown; one film frame provides 3 and 2 fields alternately. 50 Hz TV just speeds up the film a bit and uses two fields per one frame).

Filter:It's a porno AND a tissue?

[Porthwhanker]

With the quality of certain top posts on Slashdot, you really start to wonder what the general mentality is around here... Taco, we need better filters.

There *are* better filters: Preferences, Comments, Scroll down to Reason Modifiers, -6 for "Funny", Scroll down to Save. No more funny jokes.

Personally, I like to laugh once in a while.

Re:"Great" frequency?

[lars_stefan_axelsson]

Movies in theaters are usually run at 24 frames per second, in other words a frequency of 24Hz.

Actually, movies are run at twice that, i.e. in order to reduce the flickering each frame is projected twice. And 48Hz is just barely acceptable for straight on viewing. You'll see the flicker clearly out of the corner of your eye.

So, they actually need more than that, 72Hz is actually about right for something that you're sitting close to (such as a computer screen).

There's a lot of info on the net if you want to dig deeper.

Re:"Great" frequency?

[RedWizzard]

Actually, movies are run at twice that, i.e. in order to reduce the flickering each frame is projected twice. And 48Hz is just barely acceptable for straight on viewing. You'll see the flicker clearly out of the corner of your eye.

Got any references to back that up? Everything I've ever seen says movie projectors run at 24 fps (see HowStuffWorks for example). A movie projector doesn't refresh an image like a CRT - the light source is always on, displaying whatever is on the film in front of it. So you can't really project each frame twice anyway, it's projected for exactly how long it's in front of the light for (1/24th of a second minus transport time). Any perceived flicker in movie projection is due to the border between frames of film, not the light source going on and off.

a detailed paper (no pun!)

[zarniwhoop]

on this by the authors is available here

See how the 'shape' of the pixel can determine where the ink goes when voltage is applied. hmm interesting!

I prefer Magink

[*weasel]

It's also full-color, but it's static so it only draws power when changing the image, it has a refresh rate of up to 70hz (plenty for displays) and it's not backlit (making it behave just like current paper, and again, draws -0- power when not changing the image).

It sounds like the way to go imo. backlighting may be a required feature for TVs (cultural emphasis on watching movies in the dark) - but for laptops/pdas/cellphones/handheld gaming/etc - it'd easily be a killer tech. yeah, you'd have to have some sort of a front-light (like the new light on the GBA SP) for Eg. dialing in the dark, using your laptop on a plane, etc.

But having the light only when you need it will save ridiculous quantities of battery power. Imagine your gadget battery lasting 2-3x as long.
Good stuff.

article

Re:"Great" frequency?

[lars_stefan_axelsson]

Got any references to back that up? Everything I've ever seen says movie projectors run at 24 fps (see HowStuffWorks for example).

Sure, see for example the explanation from the Australian film commision. But really searching for '48 fps' and 'projector' will get you tons of hits (though granted many will be about proposed improvements to the current system). Also my original post had a link with the same info, albeit from a TV-guy's perspective.

A movie projector doesn't refresh an image like a CRT - the light source is always on, displaying whatever is on the film in front of it. So you can't really project each frame twice anyway, it's projected for exactly how long it's in front of the light for (1/24th of a second minus transport time). Any perceived flicker in movie projection is due to the border between frames of film, not the light source going on and off.

While howstuff works is generally good, they're wrong on this particular point. However, had you read their description more carefully, you'd see that what you're saying isn't exactly right. While the lamp in the projector is always 'on', the light doesn't actually always reach the screen. There's a shutter (called 'gate' in projectionist circles) that blocks the light path as the film advances. Without it, you'd see the actual film advance, and that would look funny, to say the least. Now, just gating the movie at 24 Hz produced noticable flicker, and hence the film is double gated, i.e. the shutter (really a rotating disc with two holes in it) is closed twice for each film advance.

Now if you want to go into the details of why the human perceptual system has a higher tolerance for the resulting experience, it gets involved and I don't actually know all the details, even though I really should (I do research in visualisation).

It's interesting you make the comparison with a CRT though. It's almost the reverse. The afterglow from the phosphorous in the CRT between electron beam refresh is considerable, much more so than the film frame, the light through which is just cut off between frames (and once during). I've made a post about CRT's before, you might find interesting, though it's not exactly related to the subject at hand.

Re:It's a porno AND a tissue.

[Anonymous Coward]

REDUNDANT

(was that 20 seconds that time /.?)