Pixel Qi screen demonstrated in HD quality video from Taipei

[pdurrant]

I forgot to mention the other really clever bit.

Ordinary LCD screens create the sub-pixels with colour filters that block out 2/3 of the light passing through. Not very efficient, but they're /always/ coloured.

The Pixel Qi screen creates the colour by a system of diffraction gratings and lenses that split the backlight into RGB diagonal stripes across the screen. This is why the pixels are black and white in reflective mode, and colour only when the backlight is on.

Originally Posted by pdurrant

The Pixel Qi screen does it completely differently. It doesn't have sub-pixels at all. Only square pixels at around 200dpi. This, obviously, works fine for black and white. It the adding in of colour that's clever.

[soilwork]

Originally Posted by pdurrant

This is why the pixels are black and white in reflective mode, and colour only when the backlight is on.

Thanks for your detailed explanation. However, from the video clips, they demonstrated color screen without backlight. I wonder whether this will contradict your explanation.

[wallcraft]

Mary Lou indicated 205 ppi in b&w vs 120 ppi in color. This is entirely consistent with square pixels of 3 colors, since (205*205)/(120*120) ~= 3. There is apparently some color in the black and white mode, and this might indicate that the screen isn't actually being driven at 205 ppi. As pdurrant indicated, the effective resolution of the color mode may be higher than 120 ppi anyway.

[Shaggy]

Originally Posted by soilwork

Thanks for your detailed explanation. However, from the video clips, they demonstrated color screen without backlight. I wonder whether this will contradict your explanation.

They were demonstrating the color screen in transflective mode, which is different from "without backlight". It has the backlight turned down, but it is still there.

You can think of the two color modes as "backlight on" and "backlight dimmed". When they say there is a button to switch the backlight "off", I believe they're really talking about the transflective (aka "backlight dimmed") mode. I believe the mode with no backlight at all is B&W only.

[soilwork]

Originally Posted by Shaggy

They were demonstrating the color screen in transflective mode, which is different from "without backlight". It has the backlight turned down, but it is still there.

I am not sure whether this is true. As I speculated here, this video clearly explains that they added a simple toggle switch between two-mode (backlight on and off) between 5:44-6:00.

[Shaggy]

Originally Posted by soilwork

I am not sure whether this is true. As I speculated here, this video clearly explains that they added a simple toggle switch between two-mode (backlight on and off) between 5:44-6:00.

I'm pretty sure I've seen a technical explanation of how the screen works from Pixel Qi themselves which basically says the color is dependent on the backlight, and that no backlight means no color. I suspect the toggle switch is really on-dim, and not on-off.

[soilwork]

Originally Posted by Shaggy

I suspect the toggle switch is really on-dim, and not on-off.

Again, it implies that both Mary Lou Jepson and John Ryan are lying or making mistakes when they are describing the mode as 'backlight off' rather than 'dimmed backlight'. It is certainly possible but we may need clarifications from Pixel Qi to settle this issue.

[Shaggy]

Originally Posted by soilwork

Again, it implies that both Mary Lou Jepson and John Ryan are lying or making mistakes when they are describing the mode as 'backlight off' rather than 'dimmed backlight'. It is certainly possible but we may need clarifications from Pixel Qi to settle this issue.

I wouldn't say lying, but possibly speaking imprecisely. The general audience probably doesn't know or care about the difference between on-dim versus on-off, so they could just be using a more common description. "Look, it even has an off switch" is probably more meaningful to the average user/journalist watching the demo than "Look, it even has a dim switch" (responded to with "It has a what?").

I'll see if I can find a link to their explanation that says the color is dependent on the backlight.

[soilwork]

Originally Posted by Shaggy

The general audience probably doesn't know or care about the difference between on-dim versus on-off, so they could just be using a more common description. "Look, it even has an off switch" is probably more meaningful to the average user/journalist watching the demo than "Look, it even has a dim switch" (responded to with "It has a what?").

Err, I would rather give more credit to general audience since they should know what dimmer is.

I'll see if I can find a link to their explanation that says the color is dependent on the backlight.

I would appreciate it. However, even such information does not confirm you cannot create color without actual backlight unless it clearly states it.
Since 3Qi is able to reflect light better than any traditional LCD, it may be able to achieve some backlight-like effect just by reflecting light without actual backlight. Of course, this part is my guess from someone who has little knowledge on engineering.

[pdurrant]

I suppose it all depends on exactly how reflective various layers are, and how the diffraction gratins/lenses work.

I can certainly imagine that in bright light /some/ of the light might reflect from the very back of the display, and so give some very faded colour in what would otherwise be a pure B&W mode.

Originally Posted by soilwork

Thanks for your detailed explanation. However, from the video clips, they demonstrated color screen without backlight. I wonder whether this will contradict your explanation.

[Shaggy]

We'll probably never know until more people start getting their hands on them and see what they can actually do.

I still haven't found the technical link I was thinking of. I found several blogs/articles saying that the reflective epaper mode is black and white, but those aren't really definitive.

[Sonist]

These look much better than I expected. Pretty close to e-Ink.

BUT, not as white as e-Ink. Not yet, anyway. And for my dedicated e-reader, "close" doesn't get a cigar.

So, I am keeping my order for he Kindle DX.

I am guessing, that when nice, clear, finger-touch Pixel Qi tablets come to market next year, I'll get one. Or OLED, if it comes, and is as good as they say.

But until then, I just don't see anything on the horizon, that gets close to the K DX. I am just hoping, that PDF support is robust.

[wallcraft]

What I would like to see is the ebook content displayed in backlight off and backlight on but dim modes. It would also be interesting to know what resolution the graphics controller is driving the screen with. Is it a higher resolution in the b&w backlight off mode?

These details are important, but I don't currently see any downside to a 3T screen over a conventional one. At work I run a 1920x1200 wide screen monitor with seven terminal windows open per screen, and they are all currently black text on white (cream) background. Running these in B&W non-backlight mode would save power and would probably be easier on my eyes. I do wonder if the contrast will be high enough in this mode, but with EInk screens, at least, bolder fonts boost the apparent contrast a lot. I also have one (virtual) screen for e-mail and one for web browsing, and I'm not even sure I would want color mode on for these screens all the time. I do need color for some applications, so fast switching between modes would be important. Or perhaps I go the two screens route and leave one in color. My point here is that I would buy a Pixel Qi monitor to replace (or augment) my existing monitor, but I would not by another traditional monitor. These are potentially game changers for the LCD screen market.

[soilwork]

Originally Posted by pdurrant

I can certainly imagine that in bright light /some/ of the light might reflect from the very back of the display, and so give some very faded colour in what would otherwise be a pure B&W mode.

That is exactly what I was thinking. I suspect it may be one of the advertised three modes of 3Qi.

Originally Posted by Shaggy

We'll probably never know until more people start getting their hands on them and see what they can actually do.

I agree with you and we are speculating based on very limited and sometimes contradicting information. Since we know Pixel Qi people read Mobileread, hope they can clarify these issues.

In addition, hope Pixel Qi has plans to replace every existing LCD products in the market. Seriously, I would rather have computer LCD replaced by 3Qi screen soon!

[Mr. Dalliard]

I think subtle colour is possible without a backlight. If ever you have looked at an old LCD where the backlight has burnt out, it is possible to make out a slight hint of colour.