4 ms·

This uses E Ink's Kaleido display, which uses colored pixels (subpixels) to create color. Subpixels are standard for emissive color screens, but for reflective

This uses E Ink's Kaleido display, which uses colored pixels (subpixels) to create color. Subpixels are standard for emissive color screens, but for reflective screens they result in very dark images (and consequently very low contrast) compared to paper. For example, to display a red image, the screen simply turns the green and blue subpixels black. So two thirds of the screen area is black and only one third is red. For printed paper the whole sheet would be red. And to display white, the subpixels can't turn white (they can only turn black), so they have to mix white from red, green and blue. So each subpixel only reflects around a third of the visible spectrum, while for white paper the whole area reflects all visible wavelengths. Making the colored Kaleido screen very dark in comparison. The problem is well known. If you want acceptable contrast in a color e paper screen, you need a display technology which can change colors inside the pixels, not just the brightness. E Ink does have such technology, but it is very slow and offers only very few colors.

cmiller1 3y ago
I wonder why they don't try layering a transparent LCD panel over an E-ink display. It seems like you could either intelligently turn it on and off when higher refresh rate and color are needed, or simply give the user the ability to turn it on and off manually for a lower power, easier on the eyes, mode that doesn't provide color.
- avidiax 3y ago
  The problem, at least indoors, is not emissive (LCD/OLED) vs. reflective (E-ink). You can very closely simulate a reflective display using an emissive display and ambient light sensors. That's what Google's Nest Hub Max does, and it very often looks like a framed photo (i.e. reflective). It's not like photons coming from an LED in a panel are more damaging than those same photons coming from an LED in the ceiling, that then reflects off of e-ink. Outdoors, the problem is that transmissive displays are not bright enough to beat sunlight. That's where e-ink makes more sense, and where I think there could be a real health benefit (outdoor sunlight exposure, ability to focus at long distances).
  - bawolff 3y ago
    Aren't LCD's not emmisive unless you put in a backlight? I assume that is what the parent meant.
    - avidiax 3y ago
      Yes, there are transflective LCDs. My angle is that we don't need complicated e-ink + LCD displays. Just make LCD less straining (reduce glare, automatically limit brightness).
      - jlpom 3y ago
        Transflecrive are the best of both worlds. I don’t get why there aren’t that much interest in them?
        marcosdumay 3y ago
        For a start, colored ones suffer from the same darkening problem the OP was talking about. But I also don't know why they aren't more explored. Grayscale ones would make for excellent e-readers. And you can always make the bottom layer both reflective and emissive, making the thing work well both outside and in a dark room. My guess is that LCD just standardized on a level of quality, and you won't get anybody producing anything different.
        cubefox 3y ago
        The first e-book reader, the 1998 Rocket eBook, actually used a reflective LCD screen, similar to a calculator or an original Game Boy. The problem is that these screens are quite dark even in their monochromatic version (without subpixels). The reason is that LCDs require filters for polarized light, which block a large portion of the light even for "white" pixels. This is likely why the Rocket eBook failed. E-book readers only took off when Sony in 2006 introduced devices with an electrophoretic display made by E Ink, which had contrast approaching actual paper. But unfortunately that contrast only works when no color subpixels are involved. At the time quite a few other e-paper screen technologies popped up which had much faster response times than E Ink's electrophoresis displays (Liquavista, Mirasol) and some even had (in theory) better potential to make subpixel-free color screens possible. Unfortunately none of them could quite match the contrast (and perhaps price?) of E Ink's monochromatic screens. Which was fatal, as e-readers were the main application of those screens, and those really only require a black-and-white image. So the other technologies were abandoned.
carlosjobim 3y ago
> E Ink does have such technology, but it is very slow and offers only very few colors. The new displays demonstrated by Eink corporation this year have the complete color spectrum at perfect vibrance. But they are extremely slow, taking some 12 seconds for each refresh.
- kjkjadksj 3y ago
  Those seem like an excellent replacement to the “billboard tv” you see in various buildings now
  - carlosjobim 3y ago
    For day-time advertising they seem to be superior to anything, including high-quality print. For night-time advertising, the advertisers will want the brightest possible display. A huge amount of insanely bright billboard screens have popped up in my neighbourhood recently, that are so bright as to become traffic dangers. Just waiting for them to be smashed by vandals, honestly. Edit: Here are the new E Ink Spectra 6 displays I was talking about, pardon my Chinese: https://www.youtube.com/watch?v=U7V2EFAcbtU https://www.youtube.com/watch?v=U7V2EFAcbtU
    - cubefox 3y ago
      Apparently E Ink managed to move four different types of colored particles (white, cyan, magenta, yellow) through the fluid inside the pixels: https://www.ineltek.com/wp-content/uploads/2017/08/ACeP-How-It-Works.jpg https://www.ineltek.com/wp-content/uploads/2017/08/ACeP-How-... The cyan, magenta and yellow pigments are transparent like in inkjet printers. They are used to subtractively mix red, green, blue and black. The white particles are not transparent, so they block the rest when they are on top. So E Ink is able to create the eight primary colors: https://technewsspace.com/wp-content/uploads/2023/04/1681215995_840_E-Ink-introduced-Spectra-6-color-displays-with-electronic-ink.jpg https://technewsspace.com/wp-content/uploads/2023/04/1681215... I'm not sure whether they are able to create other colors inside a pixel, but these eight are enough to create full color displays with dithering. But the problem seems to be the time required for separating the pigments. 12 seconds is absurdly long for a full refresh. I think the electrophoresis screen technology is fundamentally a dead end here. Moving solid particles in a fluid introduces drag, which will always be slow. I thought the second generation "SMI" Mirasol screen technology by Qualcomm looked a lot more promising. It doesn't require subpixels and probably would have been fast like the first generation. Here is a video from 2014: https://youtube.com/watch?v=VMDaJB2y4vc https://youtube.com/watch?v=VMDaJB2y4vc However, Qualcomm stopped investing in developing the technology shortly after it was shown. It would have worked by moving solids (MEMS) through the air instead of through a fluid, which doesn't introduce the drag problem present in E Ink's electrophoresis displays.

cmiller1 3y ago

I wonder why they don't try layering a transparent LCD panel over an E-ink display. It seems like you could either intelligently turn it on and off when higher refresh rate and color are needed, or simply give the user the ability to turn it on and off manually for a lower power, easier on the eyes, mode that doesn't provide color.

avidiax 3y ago
The problem, at least indoors, is not emissive (LCD/OLED) vs. reflective (E-ink). You can very closely simulate a reflective display using an emissive display and ambient light sensors. That's what Google's Nest Hub Max does, and it very often looks like a framed photo (i.e. reflective). It's not like photons coming from an LED in a panel are more damaging than those same photons coming from an LED in the ceiling, that then reflects off of e-ink. Outdoors, the problem is that transmissive displays are not bright enough to beat sunlight. That's where e-ink makes more sense, and where I think there could be a real health benefit (outdoor sunlight exposure, ability to focus at long distances).
- bawolff 3y ago
  Aren't LCD's not emmisive unless you put in a backlight? I assume that is what the parent meant.
  - avidiax 3y ago
    Yes, there are transflective LCDs. My angle is that we don't need complicated e-ink + LCD displays. Just make LCD less straining (reduce glare, automatically limit brightness).
    - jlpom 3y ago
      Transflecrive are the best of both worlds. I don’t get why there aren’t that much interest in them?
      - marcosdumay 3y ago
        For a start, colored ones suffer from the same darkening problem the OP was talking about. But I also don't know why they aren't more explored. Grayscale ones would make for excellent e-readers. And you can always make the bottom layer both reflective and emissive, making the thing work well both outside and in a dark room. My guess is that LCD just standardized on a level of quality, and you won't get anybody producing anything different.
        cubefox 3y ago
        The first e-book reader, the 1998 Rocket eBook, actually used a reflective LCD screen, similar to a calculator or an original Game Boy. The problem is that these screens are quite dark even in their monochromatic version (without subpixels). The reason is that LCDs require filters for polarized light, which block a large portion of the light even for "white" pixels. This is likely why the Rocket eBook failed. E-book readers only took off when Sony in 2006 introduced devices with an electrophoretic display made by E Ink, which had contrast approaching actual paper. But unfortunately that contrast only works when no color subpixels are involved. At the time quite a few other e-paper screen technologies popped up which had much faster response times than E Ink's electrophoresis displays (Liquavista, Mirasol) and some even had (in theory) better potential to make subpixel-free color screens possible. Unfortunately none of them could quite match the contrast (and perhaps price?) of E Ink's monochromatic screens. Which was fatal, as e-readers were the main application of those screens, and those really only require a black-and-white image. So the other technologies were abandoned.

carlosjobim 3y ago

> E Ink does have such technology, but it is very slow and offers only very few colors. The new displays demonstrated by Eink corporation this year have the complete color spectrum at perfect vibrance. But they are extremely slow, taking some 12 seconds for each refresh.

kjkjadksj 3y ago
Those seem like an excellent replacement to the “billboard tv” you see in various buildings now
- carlosjobim 3y ago
  For day-time advertising they seem to be superior to anything, including high-quality print. For night-time advertising, the advertisers will want the brightest possible display. A huge amount of insanely bright billboard screens have popped up in my neighbourhood recently, that are so bright as to become traffic dangers. Just waiting for them to be smashed by vandals, honestly. Edit: Here are the new E Ink Spectra 6 displays I was talking about, pardon my Chinese: https://www.youtube.com/watch?v=U7V2EFAcbtU https://www.youtube.com/watch?v=U7V2EFAcbtU
  - cubefox 3y ago
    Apparently E Ink managed to move four different types of colored particles (white, cyan, magenta, yellow) through the fluid inside the pixels: https://www.ineltek.com/wp-content/uploads/2017/08/ACeP-How-It-Works.jpg https://www.ineltek.com/wp-content/uploads/2017/08/ACeP-How-... The cyan, magenta and yellow pigments are transparent like in inkjet printers. They are used to subtractively mix red, green, blue and black. The white particles are not transparent, so they block the rest when they are on top. So E Ink is able to create the eight primary colors: https://technewsspace.com/wp-content/uploads/2023/04/1681215995_840_E-Ink-introduced-Spectra-6-color-displays-with-electronic-ink.jpg https://technewsspace.com/wp-content/uploads/2023/04/1681215... I'm not sure whether they are able to create other colors inside a pixel, but these eight are enough to create full color displays with dithering. But the problem seems to be the time required for separating the pigments. 12 seconds is absurdly long for a full refresh. I think the electrophoresis screen technology is fundamentally a dead end here. Moving solid particles in a fluid introduces drag, which will always be slow. I thought the second generation "SMI" Mirasol screen technology by Qualcomm looked a lot more promising. It doesn't require subpixels and probably would have been fast like the first generation. Here is a video from 2014: https://youtube.com/watch?v=VMDaJB2y4vc https://youtube.com/watch?v=VMDaJB2y4vc However, Qualcomm stopped investing in developing the technology shortly after it was shown. It would have worked by moving solids (MEMS) through the air instead of through a fluid, which doesn't introduce the drag problem present in E Ink's electrophoresis displays.