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Comment by antirez | Hacker News Reader

Is somebody able to explain why certain e-ink displays are so slow to refresh while others are much faster? For instance my Garmin Vivoactive HR e-ink display, that is even capable of displaying 64 colors, is like an LCD display in terms of refresh rate apparently, you can't see the difference easily, while the one that was used to build this project takes a lot of time to even show a single frame (see the Youtube video where the display is presented, following the link Jann provided in the blog post). My best guess is that they use completely different technologies.

EDIT: Vivoactive HR uses a Transreflective LCD actually. This web site explains very well how it works:

http://t17.net/transflectiveTFT/

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That's because your Garmin actually uses a type of 'transreflective' LCD and not e-ink...

https://en.m.wikipedia.org/wiki/Transflective_liquid-crystal...

Ok cool, thank you. The contrast is actually not like an e-ink display, but under sunlight it becomes excellent.

Does that really have an e-ink display? Their specs page says "sunlight-visible, transflective memory-in-pixel (MIP)" which seems to be a type of LCD that has characteristics like e-ink.

Also: Thanks for Redis!

Yes, you are right... different tech indeed! Works as a very good approximation of an e-ink frankly (I've a few kindle readers for comparison), but the contrast in artificial light is not as good as e-ink. Thanks! (and you are welcome).

Depending on what updates you need, you don't need to do a full refresh of the e-paper display (there will be some ghosting, though). Check out this video from papirus: https://twitter.com/gregeric/status/849218168224702465 That updates pretty nicely. And thank you for making redis!

Very cool! Thanks

Also, IIRC e-ink is trademarked, e-paper is just any display with paper-like appearance. Marketing!

> Is somebody able to explain why certain e-ink displays are so slow to refresh while others are much faster?

Sometimes it's the interface rather than the eink. The one in the article is a serial SPI interface. If the interface is parallel, instead it can be 8x, 16x, etc. faster

I believe it's just due to the niche application space.

2012 era Nook eink reader playing a game with hacked refresh:

https://www.youtube.com/watch?v=9fbD753xE-U

The tech can do better, but as I've heard it told, the market for it has been eink readers. Who needs to refresh their book at 120hz? is the thinking. Folks that want to game or have a "retina" resolution buy a tablet proper.

Upping refresh has steep power costs too. Ereader marketers like their "recharge once every 6-8 weeks!" message.

> The tech can do better, but as I've heard it told, the market for it has been eink readers. Who needs to refresh their book at 120hz? is the thinking. Folks that want to game or have a "retina" resolution buy a tablet proper.

Personally, I'd love to read most web-pages on an e-ink display, due to the high contrast, minimal power usage, and great readability even in direct light. I don't care hugely about usability for dynamic content, but I'd want fast scrolling with no update artifacts.

Related question: what's the state of color e-ink displays? Seems like it should be possible to produce a bi-stable display with a little bit of color depth, even if just through filters and dithering.

> Related question: what's the state of color e-ink displays?

They demonstrated true color in 2016. https://www.youtube.com/watch?v=N2V9iuTW3sA I would guess another 3 to 4 years to consumer availability.

That's really impressive. I look forward to seeing that in production.

(Also, some searching suggests that it's "tens of thousands of colors" rather than true color, but that's still a major improvement, and more than enough for the majority of the web sans photographs.)

> "tens of thousands of colors" rather than true color

My meaning by true color was color achieved through actual pigment pixels versus older E-Ink products like triton that achieved color through LCD-like RGB color filters on top of reflective/non-reflective pixels. The difference between the two is quite stark.

They stopped bothering. They had some demo screens a few years back, mira-something I think, and a few products that used it, but nobody bought it because the colors were terrible due to the entire "e-inks generally don't require backlights and so massive contrast issues" I think the tech got bought up and pretty much shoved in a corner somewhere

Mirasol display is I think what you're trying to recall. I still have one; a Kyobo Android 'tablet'. In typical tablet usage conditions (i.e. indoors, probably at night on a bed) then yes, mirasol displays and color e-ink screens never matched LCDs and SAMOLEDS. Mirasol was decent/serviceable imo while color e-ink has been truly terrible.

However in outdoor conditions (e.g. at the beach or a park) I still haven't seen any iPad or Samsung display as pleasing as my old mirasol display without backlight. If someone released a new mirasol display ereader today, I would buy it in a heartbeat

If you're refreshing rapidly, you might lose a lot of that battery life, based on my experience with extended fast reading sessions on my Kindle.

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