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Comment by avidiax | Hacker News Reader

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).

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Aren't LCD's not emmisive unless you put in a backlight? I assume that is what the parent meant.

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).

Transflecrive are the best of both worlds. I don’t get why there aren’t that much interest in them?

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.

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.

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