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Reasonably priced color e-ink display (waveshare.com)
413 points by zdw on July 20, 2020 | hide | past | favorite | 208 comments



So, why exactly is it that color e-ink displays try to make every micro-capsule capable of switching to any of the supported colors; rather than laying (groups of) CMYK micro-capsules out in a subpixel-like arrangement, and then wiring them to the substrate such that each of the CMYK "bitplanes" forms an independently-addressed display signal?

Sure, it'd look like badly-registered offset printing, but that only matters for small up-close displays, not large far-away displays. (And you could fix the registration with a precisely-cast diffuser layer, convolving each subpixel-cluster.)

If this was for reading rather than imagery, and you wanted to have true blacks, you could also just step one level forward in e-ink technology, and have the colored micro-capsule groups be just dual-tone (the capsule's color plus black), giving you {C+K, Y+K, M+K, K} bitplanes.

Are e-ink display manufacturers just imprecise in the way they deposit the capsules into the panel, making it impossible to address individual capsules? (If so, that seems like something that could be solved pretty easily with modern photolithography processes, e.g. etching onto the backing electrode a grid of "buckets" for individual micro-capsules to fall into.)


Yes, modern e-ink capsules are not precise. In fact, they're not intended to be.

If you look at an e-ink display under a microscope you'll see that the "pixels" are more like "shards" of variously-shaped cells.

https://twitter.com/sqfmi/status/1178018736684580865

The "pixels" are made of the actual addressing grid that creates the currents that attract the pigment in the capsules.

This is part of what ends up giving the appearance of a higher-resolution display when rendering text, as you get some softer edges "for free." (And it's what makes the display look 'blurry' for some viewers.)

So, to your question, there's currently no attempt with the technology to precisely place the colors on the display. The capsules are just spread all over, and the grid does the work.


This makes me sad. Based on what you're describing it's sounding like my dream of having eReaders that are anywhere near sharp enough to do visually rich, full color, documents justice (e.g. nature photography, comic books and graphic novels, well illuminated manuscripts) will never come to fruition. Barring some kind of transformative breakthrough, of course.


https://upload.wikimedia.org/wikipedia/commons/thumb/a/a6/Co...

Rods in eyes aren't on a regular grid anyway, why should it matter how the pixels are distributed as long as they cover the plane and are mostly uniform?


Because of what was mentioned way up in the original question: The capsules not being precisely arranged means that they can't be individually addressable. Meaning that you can't use the trick that non-epaper screens typically use where each "pixel" is actually a tightly packed cluster of individual red, green and blue sources that are individually controlled.

So instead, each cell is capable of displaying any color, and they've got a more complicated refresh mechanism that they use to "write" to them.

And the upshot of that is listed in the specifications from the linked page: The refresh time on this display is 15 seconds. Which is far, far away from where it would need to be in order to be a practical option for color e-readers.


Except you can do multiple colors, by introducing differently charged pigments inside the capsules:

- https://www.eink.com/assets/img/technology/GIF_Cup_E.gif

- https://www.eink.com/assets/img/technology/GIF_ACeP_E.gif

Refresh rate was always an issue, but it is gradually improving. For static reading it's not a problem.


I have the 2.7” 3 color (b) hat, and it is very slow with stock code. As far as I know, and from the looks of the Python code, 2 full buffers are transferred for the colors and then a process of wave stimulating the fluids into arrangement are how it works, very conservatively and slow. There has been work done to the firmware to allow partial updates fast enough for animation, but they should be used sparingly to avoid temporary or permanent burn-in, they say.


> Meaning that you can't use the trick that non-epaper screens typically use where each "pixel" is actually a tightly packed cluster of individual red, green and blue sources that are individually controlled

If there was a way to mix the inks and have them 100% separate by the grid on demand, it could be possible.


Who designed these ‘eye’ things anyway, sounds like they took a lot of engineering shortcuts and amassed a metric boat-ton of technical debt


Let it thus be observed that a truly intelligent designer understands how to live comfortably with technical debt.


If I was all-knowing and omnipotent, I'd be OK with that in my code as well.


Isn't tech debt a sign of not being all knowing and omnipotent?


There's always tech debt. It starts to day you build something and ends when it stops being used. How many thousands of python 2.7 programs had "no" tech debt when developed bit now have tons. Tech debt isn't binary, it's a sliding scale.


Seems like a classic-style omnipotent god could write anything conceivable in some eternal Lisp dialect that he maintains personally. If he’s really capable of violating thermodynamics he should be able use knowledge of the future to ultra-waterfall the design and implement it flawlessly thereby completely avoiding accumulation of technical debt.

It’s fun to imagine Jesus returning in 30xx AD but this time instead of absolving the world of its accumulated sin he wipes away the accumulated technical debt of 1.5 millennia worth of corporate IT


If you were "all knowing", you would've known that Python 3000 would not be backwards compatible and waited until it is released (assuming that you don't have a deadline, such as 7 days).


Even if you had a deadline, you'd know all tech debt and could anticipate it beforehand.


The joke is (and it is a joke, mind you) that an omnipotent and omniscient entity could have written a perfect program in, say, 2005, and it would have no tech debt now, because it's never needed to change since it was written to anticipate every need for the program in the first place.

Hell, since the writer was omnipotent and omniscient, the code was even built with the ability to perfectly modify itself when the company changed the DB on September 12, 2011 at 3:24 in the morning.


You mean all the Python programs started before 2008, right? Because that's when it was announced that they were sunsetting Py2.

So any projects started since 2008 that were written without Py3 compatibility had known tech debt they were choosing to take on.


Yes. Why does it matter than the particular example I chose had a cutoff date 2008? It's the same issue with any language, program, platform, OS, etc. Even if you implement the latest stable version of any of these things for any project, tech debt begins immediately. In fact if you're dealing with established enterprise software, you know right away what the roadmap & minimum end-of-life is from the day it's released. (as side topic, that's part of why mediocre enterprise software is often chosen over newer better options: because predictability is valued over the newest/best/fastest that may be subject to disruption if the vendor goes away or gets acquired-- something I've seen happen a few times. A vendor gets acquired, we get a "Hey Great News!" message from them along with an "Oh by the way our new parent company is transitioning everyone off our platform to their own completely different offering over the next 6 months, hope you have the capacity/bandwidth to deal it #sorry-not-sorry"


> over the next 6 months

My point is this is a very different situation from the Python 2->3 transition.

If you have 12 years' notice to make some changes, I don't consider that technical debt: that's the normal price of maintaining software in a changing world. It's not "debt" that costs "extra interest" to pay back for questionable choices made previously.


No. Tech debt, like money debt, can be taken on in purpose to be able to take advantage of a short term business opportunity.


The joke is (and it is a joke, mind you) that if you're all knowing and omnipotent, there's no such need to take on tech debt. Because you will have already known about the short term business opportunity and coded it (without tech debt since you also know all of the requirements, pitfalls, and corner cases perfectly) before it was needed.


I don't know.


Let me introduce you to the fall of man.


"How did we justify this whole 'cancer' thing being SEV-1? I really don't see the urgency."


It's what happens when your rookie engineer leans too heavily on generative design instead of doing their homework. :P


Product management kept changing the requirements!


colour printing is often made from randomised dot screens, so long as they are small enough its fine.


I think the solution is a dual eink and oled display. Overlay a “transparent” oled on top of an epaper screen and use the oled to display colour images and video while using the epaper for static monochrome regions.

I’m not sure that current “transparent” oled technology is transparent and thin enough though.


This sounds really similar to https://www.mobvoi.com/us/pages/ticwatchpro which is a Smartwatch with a dual layer display, one of them is e-ink, the other is an AMOLED display.


Do a search for hybrid eink LCD display; Apple and others were looking into this 10 years ago; the Pixel Qi's 3qi displays were apparently manufactured and used in at least some products, then Apple applied for a more complex patent as well. As far as I can tell, both systems seem to use a layered display.

https://www.pcworld.com/article/165724/bye_bye_kindle_netboo...

https://arstechnica.com/gadgets/2011/04/apple-exploring-hybr...


eink should die already. There are other options rather than eink, microLED and some of the newer low refresh LCDs (Clearilk comes to mind) should be much better. https://www.displaydaily.com/article/press-releases/clearink... Lenovo is interested and made a thinkpad with eink so it shouldn't come from a weird no name company in the future.


Do the others ones not consume power when you don’t need to change the display, are legible in daylight, or otherwise not emit light?

These are unique advantages to e-ink as far as I’m aware.


It doesn't matter for a stationary screen


It certainly does depending on your application. Grocery stores use them for prices where you wouldn't want a glow and low power means you can run off a battery. If I integrated into my walls as a smart device I would want a subtle design without a glow. These are just two examples off the top of my head. The application matters.

Also where did this stationary context come from?


People are asking about using it as a monitor in the comments. Grocery stores can do wireless power but the comments are complaining about them being too big or small.

You can easily have a non backlit black and white display, like the one on an f91w or LCD clock.


The contrast ratio will never make it good for text. I have used the so called high res ones and I would take a 720p LCD any day. They are trash.


As a reflective display, you want to optimise for the percentage of useful light reflected back to the user. Switching the white (or black) out for another colour will necessarily reduce the contrast ratio of the display, which is of course not ideal when you don't have much light to work with in the first place (as it's a reflective display after all). That's why reflective LCD displays were pretty much a disaster, since the LCDs require a polarisng filter which absorbs a large portion of the light, and reflective colour LCDs more so, because that multiplies with the effect of the colour filters.

Of course, you could simply make a matrix of tri-tone capsules, with white, black and colour. Then you have the contrast ratio and the colour space advantages. I don't know why this hasn't been done, I'm not an expert on e-Ink!


Colored e-ink displays are discussed at around 8:00 in this video; there are probably better sources, but this is the one I'm familiar with, so I figured I'd link it: https://www.youtube.com/watch?v=MsbiO8EAsGw

The microcapsules are not individually wired up to anything, so I don't think it's feasible to make each color channel independently addressable. Instead, a grid of wires behind the capsules are either positively or negatively charged, in order to attract or repel the charged colored particles in each capsule. There are only 2 charges, but by using different sizes of particles for different colors, you can finagle it so that the color you want ends up on top.

If they could address capsules individually, that would also increase the possible resolution of a black-and-white display; they'd do it if they could. But since the mechanism is about attracting and repelling charged particles, there's probably a pretty hard limit on how much you can increase the resolution before there is interference between neighboring pixels.


> And you could fix the registration with a precisely-cast diffuser layer, convolving each subpixel-cluster.

Would that still look like paper, though?


Although nobody implemented this yet, I'm guessing someone did patent it already ...


Perhaps someone more familiar with the technology can help me understand. Why are e-ink displays either tiny (tablet-sized or smaller) or huge (for digital signage)? I always thought it would be cool to have an x-teen or 20 something inch e-ink monitor to make reading docs, specs, etc. much easier. I realize the refresh rate on these things is pretty low, but I've read accounts of some screens being clocked to around 20hz which may not be enough to watch videos or play games, but it would be ok for reading and scrolling.

OTOH I did see a 30 something inch e-ink development board for sale once and wondered if I could hack one together. It was expensive, but that didn't particularly matter because the company made it clear they wouldn't sell to consumers or hobbyists.


There're a few things going on that contribute to this.

1) The rumors are that some of the display manufacturers have contracts with big device makers to not sell panels direct to consumer. I don't have evidence to verify this, though.

2) There aren't a lot of displays that exist _at all_ outside of the small/eReader/Big Sign categories. So there probably just aren't the production lines out there to push those out.

3) Since refresh rates in even the best cases aren't great, it's unlikely to get a lot of traction in most markets, so I don't think anyone is pursuing it heavily.

4) eInk (the company) seems very uninterested in the hobby market at all. They seem to want a few big contracts, and that's all they're interested in.


For point 4, that could be a pretty smart move on their part and the reason they're able to keep going. Selling directly to consumers/setting up the distribution and marketing for that etc would be really difficult and a lot of D2C hardware companies have not done too well recently. It's unfortunate that it results in it being difficult to access for hobby markets, but relying on large, stable contracts from a lot of big manufacturers that already built up marketing and distribution over decades of operations is probably one of the better ways to commercialize a hardware innovation today.


I feel eInk’s marketing strategy has really held the technology back. They seem to want to force the technology into a few well-defined verticals that they came up with themselves instead of letting an army of smaller companies innovate rapidly.

They were founded in 1997, so their earliest patents have probably expired. I wonder when the clones will arrive. Maybe they’ll have a better marketing and sales strategy.


Those don't seem like valid reasons not to offer for sale to consumers. Distribution is a non-issue. Literally ship in a case of them to FBA or one of the countless other fulfillment operations and put up a listing. Amazon handles the customer service.

As for the marketing, just don't do any. Let the hobby market find it on their own and then just set a minimum order for anyone that wants to work directly with the company for their small project.

I think getting into the hobby market would amount to a huge long tail market of kickstarter style projects and other small products with potential to blow up.

I really don't see how their current strategy could be that great considering how rare it is to see products out there that are e-ink.


> I think getting into the hobby market would amount to a huge long tail market of kickstarter style projects and other small products with potential to blow up.

I'm trying to think of a single kickstarter-style project that generated a volume above even 100K units let alone a million. I can't think of any.

BeatBuddy is probably the most successful by unit volume project I can think of, and they're probably under 10,000 units.

So, the evidence is that the hobbyist market is completely useless to manufacturers.


Well yeah, but that's not where the money is in selling to hobbyists.

If you want someone to invent something that uses them, you'll have to have them in the hands of people that invent stuff. Maybe you only break even on your small scale sales to hobbyists, but eventually one of those hobbyists will be the one to invent the next big thing.


My point was that over the last 5-10 years, we have seen ZERO hobbyists create the Next Big Thing(tm) out of a kickstarter-like.

And, I would argue, for two good reasons.

1) When you think about things like the Homebrew Computer Club or the Tech Model Railroad Club, the point is that the membership were engineers. Yes, they were hobbyists, but they were already professionals in the field. Kickstarters don't seem to attract that engineering crowd.

2) Anybody with actual knowledge of hardware laughs at the amounts that kickstarters raise. Most engineering professionals can personally move the amounts of money that most kickstarters can raise.

The combination of the two is death for the Next Big Thing(tm) coming out of a kickstarter.


Oculus and Pebble maybe aren't "Next Big Thing", but both were major hardware Kickstarter projects. Pebble was the first mainstream smartwatch, and the VR landscape would be significantly different if not for Oculus. It's probably fair to say that neither was iPhone level of industry revolutionary, but it's a mistake to discount them entirely.


My comment wasn't about Kickstarters, I think they're irrelevant in this discussion. I'm talking about making your stuff accessible to people outside of large corporations. The world isn't two perfectly non-intersecting groups labeled "hobbyists" and "professionals". There's enormous overlap. Hell, a very large portion of HN falls into both categories.

Let's say XYZ software is only available to businesses. As a professional software engineer, if I asked to buy XYZ, it'd get bought. But since I can't use XYZ in my personal life, I've never even heard of it, and as a result when we're deciding on software to buy at the company I have no familiarity with it and it doesn't get bought.

Perhaps somewhere out there there are some 100x hardware developers, but every hardware developer I've met likes what they know, and a lot of what they know from a combination of personal tinkering and university. It's hard to explain how powerful familiarity is with designing hardware. So if you're sitting down and designing something and you need component A or B, and B uses less power and looks cool and all kinds of stuff, but you have experience with A and it works fine, well, you'll go with A. And for good reason! Things have weird quirks and spec sheets lie and all kinds of stuff happens.

So yeah, I think that having some kind of community connection can pay absolutely massive dividends. At the end of the day, if it's only accessible to large corporations, then it's not even accessible to those large corporations - because the engineers at them won't have familiarity with your thing and they'll just pick what they know.

Furthermore, it's not even that hard to sell to hobbyists. You make the spec sheet public, you make some example code public, you mail some units to Digikey and you're done. You wanna go REALLY crazy, you can mail a few free units to some well known tinkerers. It's not like you're personally offering 24 hour phone support to everyone with an Arduino. The investment of a couple of hours to deign to mail Digikey a box is quickly recovered by the first engineer that plays with your widget at home and then suggests it at $bigco.


Kickstarters don't seem to attract that engineering crowd.

As an engineer whose project proposal (with proof of feasibility in the form of working and one-at-a-time manufacturable fully functional prototypes) was rejected by Kickstarter back in 2017, maybe their selection criteria are the reason.


Interesting. I didn't even know kickstarter had selection criteria given the amount of pure slop I've seen on there.

But, yeah, if they do, that's simply going to kill the feedthrough as nobody can predict what's going to become big.


For the sake of accuracy: that 2017 was a typo and should have been 2012 or 2013.


Why would only the initial kickstarter matter? There are several major brands/companies that started on kickstarter and then went on to sell quite a bit. Pebble raised millions. Oculus started out on kickstarter and sold to facebook for a couple billion and are currently selling units faster than they can make.


Pebble raised $10.3M in Kickstarter. I didn't find how many units that was, but with retail price of $99 that should fit your criteria. Also, was using eink.


IMO, Point 3 is not really a problem, at least in the e-reader usecase. Even typing isn't too bad when partial refresh is enabled. Something like VIM on a black&white panel with kindle-grade refresh options seems quite reasonable.

Now then, with the linked screen's 15 second refresh time, this is obviously not the case. But it (naively) seems like a compromise to keep the cost low, since the added tech and software to enable partial refreshes would add to both price and complexity.


I've been wanting to get some dev kits to play around with, but they're pretty expensive and not custom enough for my intended use case.


What do you mean by 2? Monitors and TV screens fit that range, no?


Why would you want a monitor or a tv screen with a refresh rate of 7 fps? And that's monochrome. For actual RGB output, you need three refreshes, and the RGB ones are slower, so you might get a frame per second.


Because I use that monitor to read and write text. Lots and lots of text, very little video. 7 fps is abundantly adequate for reading text if you only interact with it by hitting 'page down' every 30 seconds, and if your typing is accurate enough that 150ms delay between hitting the key and seeing the character doesn't cause errors it's fine for writing text.

I don't need 30, 60, 120, or 144 Hz refresh rates to work with text. It would probably be impossible to see the difference. What I need is contrast and brightness settings to limit eye fatigue, and that's where e-ink would be great.


I'd be ecstatic with a monochrome 20"+ eink monitor for use after 8:00PM or so. With the F.lux settings I use on my normal monitor it's practically monochrome anyway.

7FPS is probably not quite high enough, but I've seen 10-13" displays with 15-20FPS, and that would be fine for normal computing.

I'd probably swap my scrollwheel for PageUp/PageDown to make full page refreshes a little more pleasant though.


There was a brief interest in transflective LCD technology in the 2000s and early 2010s but it seems to have died off (at least for consumer products), which means sunlight-readable (or candle-readable, for the evenings) LCD with high refresh rates.

There was even one company (edit: Pixel Qi) putting solar cells in the displays themselves, so the device recharged while being used in sunlight.

YouTube video comparing Pixel Qi in sunlight with normal backlit LCD https://www.youtube.com/watch?v=l1mD6vhp3U8#t=1m45s (around 01:45)


7 pfs are not a showstopper for a console

I don't know why one would want a huge daylight visible console, but it's one of those things where I'm just not creative enough.


I don't know why one would want a huge daylight visible console, but it's one of those things where I'm just not creative enough.

Not exactly a command line terminal, but there was an ambient signage project on HN recently: https://news.ycombinator.com/item?id=22831323

Also https://onezero.medium.com/meet-accent-352cfa95813a


A monitor sized e-ink display would be unusable as, say, a PC display. E-ink refresh rates makes e-ink useless for video, scrolling, etc. I have a feeling one's really come up with applications where a monitor/TV sized very slowly refreshing screen was useful so there's no demand.


> E-ink refresh rates makes e-ink useless for video, scrolling, etc.

Or even simpler -- a mouse cursor is essentially unusable on an e-ink display. Much like an old passive-matrix LCD, you'd need to implement nasty workarounds like cursor trails to restore any semblance of usability.


I use Dasung's e-ink monitor (Paperlike Pro) daily. A mouse cursor is fully usable. You can even watch videos on that thing. Of course, the refresh rate is far from perfect, but its performance is acceptable. I code on it, mainly.


I use a tilling window manager and would love to just pop a window into an external eink display.

Works for other types of wms too, just use a main display to browse and the eink to read.


I meant no one is currently making E-ink displays of those sizes in bulk. Sorry for the confusion.


I believe the question you were answering was asking why that is.


My point was that there's no current wide-spread use of low-refresh displays in that size category, because all the obvious use cases slide around it, so there isn't going to be spillover into a new use-case when there's nothing there to spill out of.

I'm probably just muddying the waters at this point.


> The rumors are that some of the display manufacturers have contracts with big device makers to not sell panels direct to consumer.

Would that be legal?


How would it be illegal?


Some otherwise fine anti-competitive behaviors are illegal when committed by monopolies.


> It was expensive, but that didn't particularly matter because the company made it clear they wouldn't sell to consumers or hobbyists.

I created an LLC a few years ago to route my moonlighting consulting work through.

Even if my need for it dries up eventually, I'd still probably keep it around. Single greatest benefit of having it is ease of access to the commercial and industrial supply chain and slipping through these sorts of "no consumer or hobbyists allowed" sales positions.


I found this 10.3 inch monitor on their site, it's quite expensive though https://www.waveshare.com/product/displays/e-paper/eink-disp...


I wonder how well that works in practice. At 15hz refresh I think it’d be fine for vi.


In contrast with sibling comments, I think it would be just fine. VIM was designed for high latency, and even the modern versions do pretty well with a second or two of lag. Issue a command, wait for the response.

The big thing is not depending on the screen keeping in perfect sync with your typing. I know this causes an issue for me when it's related to talking - an echo off by a hundred or more milliseconds will absolutely throw me off the rails - but it doesn't bother me so much when typing. A mental relic of writing code in terminals connected to distant servers, I'm sure.


Somehow as I'm very used to respsonsiveness in vi, anything less would feel quite sluggish.


Typing at 15hz would be miserable (personally).


Not for me. I regularly have vi sessions running over 3-4 cascaded ssh sessions (and a couple VPN connections in there too). Its usable, but the delay messes with your brain if you are an experienced vi user.


If the delay is consistent, it shouldn't be too bad. I spent 3 weeks on a business trip to Europe, when my devserver was in Sunnyvale, and did all my editing via ssh as I usually do (in joe, not vi, but pretty similar) and it was mostly fine --- I do recall doing some tunneling to reduce the latency a bit though. It was not as fine when they sent me to India with the same development setup, so there's a limit... But it's closer to 200ms than 100ms, so 15hz should be ok in my mind.


https://www.waveshare.com/product/displays/e-paper/12.48inch... screen without the hdmi interface is much cheaper


Dasung has been selling a 13-inch-ish for a while: https://www.amazon.com/Dasung-Paperlike-Front-Light-Touch-Mo...

But that's still within the "arguably a tablet screen" size range.


The Onyx Boox line has a 13.3" display version. They mainly cater to musicians using them for sheet music but I have a friend that consumes textbook PDFs at a pace of about 3 per week that swears by his.


For those who care, there have been recent reports that Onyx are actively and deliberately violating GPL.

https://www.reddit.com/r/Onyx_Boox/comments/hsn7kx/onyx_usin...


I also have one of these and I really like the 13" screen. Recommended, though pricey.


The remarkable isn't quite that big, but nice for PDFs (and annotating them as well) https://remarkable.com/


Sony makes one, too, but it seems to hobbled by not running a real OS to make it useful. All it does is read PDF files.



I've very much wanted to tile them across a wall of my house to make a virtual/dynamic "smart wall" for quite a while. Even a B/W version would be sufficient. Last time I checked in was late 2018 and at that time there wasn't a good sub-six-figure solution. It'd also require a lot of manual work on each cell since the cells didn't have a zero width bezel for gapless tiling.


> because the company made it clear they wouldn't sell to consumers or hobbyists.

But if you have a business address it always allowed to request a sample.


There are serious trade-offs in these things:

• In monochrome panels, you can get 16 shades, and a full refresh in under a second (with partial refresh much faster, as tight as very few milliseconds for small areas, or commonly 30fps full-screen update if you’re willing to compromise a bit on image quality).

• In colour panels, you don’t seem to get shades or rapid refresh: seven colours means you get a seven colour palette, so you’ll have to use dithering to get any in-between colours; and you don’t get partial updates at all: even the fastest coloured panels take a couple of seconds to update the image, and the more colours you add the slower it is.

If I’m wrong about these and there are colour panels with more interesting colour or partial refresh, I’m interested to hear. I just haven’t seen any, and have done some looking.

The long and the short of it is that colour e-ink displays are only useful for display use, not for individual devices like ebook readers or computer displays.


Was just about to ask the refresh time, I specifically chose this one due to it's faster refresh time (1 s) compared to color displays: https://shop.pimoroni.com/products/inky-what?variant=2121402...


You pretty much do two full refreshes, and then some. The first one drives the pigment (red,yellow) layers, and then the black ones.


Why does the refresh time depend on the size of the region updated? Forgive my ignorance—I'm imagining that the limiting factor would be the time it takes for the grains to physically flip over, because they all flip concurrently.


Only one row at a time has voltage applied to it. In one update, the image is scanned out multiple times, so it appears as if all pixels were changing simultaneously (and perhaps they do, if the electrodes have significant capacitance.)

With fewer rows to update, each row gets a push more often, flipping the grains faster.


Hypothesizing a bit here: maybe it's like flash, where erasing is slow and has to be done in large chunks, but once a large chunk is erased small chunks can be written (once) quickly.


And the dithering isn't even that great, as not all color combinations are easily-mixed, given their varied densities.


I am desperately waiting for semi-high refresh rate (20Hz-30Hz) e-ink displays so that I can replace my traditional HD display with them.

They're significantly easier on the eyes and they're a joy to use. I don't particularly care about color. One thing I'm wondering though, is what are the technical challenges behind building such a display?

Ideally, I'd like to be able to use an Android device that renders onto e-ink. I don't particularly care for watching videos and such - most of my time on my phone is spent sending and reading IM's (Signal, text, e-mail) rather than viewing media, so lower refresh rates is not something I really care about.

Where are the shortcomings causing e-ink displays to have very low refresh rate? Does it have to do with modern rendering technology being so well optimized for color displays that they simply are not performant for e-ink?


Here's how these work:

1) Take a fluid, color it mostly white(ish).

2) Suspend a bunch of tiny black "balls" inside this fluid. The balls need to be charged so they can be attracted to an electric field.

3) Squish this fluid between some glass.

4) Put a grid of electrodes on the back that you can address.

5) Now, using some clever AC patterns, you can address any "pixel" on your grid, and apply a charge there, that will attract or repel the little balls.

6) When you attract the balls, that spot turns black, because you just see the balls above the fluid.

7) When you repel the balls, that spot turns "white" because you just see the fluid, not the balls.

The trick is that moving the balls back and forth (6/7) is a physical process, and requires time. They _have_ to move a physical distance, and if that fluid lets them move too easily then they won't keep their color. The balls will move and they'll just drift back to some middle ground.

Also, if you're not careful with your approach, you can mess with the charge of the balls, and they'll no longer respond to the field the way you want. This is burn-in. (And it's why displays do full-black-to-full-white refreshes from time to time)

So until we can figure out how to move those balls faster in the fluid, we really aren't going to dramatically improve refresh rates with this technology.

Note: "Balls" is a simplification.


I wonder if it will be possible in the future to apply a similar concept for for a 3d e ink desplay where the grid pulls cells through a 3d medium.


3D doesn't really work that way.

If you want a volumetric display, maybe it will work, but the display itself will need to be the same size as the total volume of depth you want to create, e.g. digital objects can not appear outside the screen.

Due to the fact that eInk is a non-backlit technology, I can't imagine creating a glasses-free stereoscopic effect using eInk.


Thank you for the simple explanation of this tech!


Thanks for this explanation, really interesting


Take a look at the Onyx Boox Max series:

https://onyxboox.com/boox_max3

They're 13.3" displays, work with Android and you can use them as an external HDMI display. However, the refresh rate is still poor, not nearly 20-30Hz. The Technology Connections Youtube channel has made two very interesting videos, showing the many caveats of the device (it's an older model, but I'd guess most of it still applies). The main issues are poor software and slow CPU:

https://www.youtube.com/watch?v=7NfX0vlCa4k


I recommend going to https://mobileread.com/forums to read about user experiences with Onyx and other makers. They are interesting devices but the support level is not at the same level as a Kobo/Nook/Kindle. I used to have a Boyue Likebook Mimas, which was a great ereader hobbled by a slow processor and itchy software.


As far as I understand the technology, it's slow because you are physically pushing/pulling pigments around in little cells. It's simply not as fast a process as passing voltage across a crystal or shooting an electron beam.


> Ideally, I'd like to be able to use an Android device that renders onto e-ink.

You can buy one now. The money will (probably) be used to improve this technology.


If you are having issues with the site loading you can try this archive link https://web.archive.org/web/20200717131125/https://www.waves...


Thanks for the link. Looks like they've been hugged to death at the moment.


I'm still sad that the Mirasol displays (https://en.wikipedia.org/wiki/Interferometric_modulator_disp...) never made it into mainstream products. They seemed to be the best of both worlds: high refresh rates, colour, and no power consumption when not refreshing.


I had one of the qualcomm toqs (which used a small mirasol display).

It didn't look that much better (or distinguishable, for the matter) than one of those reflective LCDs (e.g. Pebble's). And reflective "memory" LCDs also have almost negligible -- though not zero -- power consumption. Except for maybe signage products most people don't care about this difference, and LCD is way cheaper and mainstream, so...

It's no surprise that many manufacturers just put an LCD and try to get away by calling it "ePaper". There is a lot of geek appeal here, but I'm not really sure if we really need any new technology for "mainstream".


Also had a Toq. Probably one of my favorite smartwatches, and would have loved to see it live long enough to run Android Wear. Unfortunately, Qualcomm isn't a product company and the Toq was essentially a proof of concept for both Mirasol and their new (at the time) line of smartwatch-focused Snapdragon chips. They managed to convince most of the major real smartwatch OEMs to use Snapdragon but the Mirasol just never got off the ground. Apparently manufacturing was very difficult, as you might imagine, and they were hitting limitations on pushing the color depth.


I had a Mirasol tablet. It sucks. Contrast is super low and I think image flickered until it would “settle”. Refresh rate wasn’t great either.


Sounds like low saturation tho? I wonder if they lost out to transflective LCD (at least in mind-share, since those haven't been shipped much either, though there are a handful of products using them), as keeping an LCD "set" is cheap enough to often not be an issue.

That is a really neat technique though, I hadn't read up on the details before.


Me too, the demos looked fantastic! Maybe after the patents expire other companies will pick up the tech.


Waveshare is really great for making eInk accessible to makers. I've got several of their products and I love them. Design and documentation are excellent. For most products they even provide libraries and/or sample code. I usually order from them directly, though it comes from China it's fairly fast compared to aliexpress and the like (think more like 2 weeks than 2 months)

By the way, one thing I don't get is why the pictures have such low saturation but the "demo" view shows really excellent saturation. Are there constraints when mixing colours perhaps?

Edit: This was explained below by sparker72678: https://news.ycombinator.com/item?id=23900165 . I didn't know they worked this way.


I've been using a 13.3" Dasung Paperlike HD-FT monitor for a few months. I use it without the front light, and set the display to 2x magnification. I'd highly recommend it to anyone having problems with LCD screens. http://dasungtech.com/


How have you been finding it? Do you use it as your main monitor? (Or only at specific times / alongside a traditional monitor?)


It works perfectly for reading documentation, writing code, and browsing the web. The refresh rate is fast enough to watch movies, but I haven't done that yet. Switching windows leaves faint artifacts on the screen, but I barely notice them, and there's a refresh button if I want to look at a detailed still image. I use it as my only monitor, and keep my laptop screen turned off. About once per week I'll toggle to my laptop's color monitor to view the art of a Kickstarter campaign, etc.

I don't miss color syntax highlighting, and it's much more relaxing on the eyes. I could imagine others using it as their main monitor in a joint display setup, code in e-ink, browser in color.


For that price might as well get a ThinkBook Plus. https://thenextweb.com/plugged/2020/01/07/lenovo-put-an-e-in...


Wait a sec, they have multi-color e-ink now and not just red or green? I cannot wait until we can get large versions of these that can hang on my walls! I'd love to put them in frames and have different paintings rotate in and out.


I've been considering building a 2-way mirror display with a regular lcd myself. Would prefer a larger e-ink, but they just seem too expensive for what they are.


The display has an SPI interface with a 15s per page refresh rate and is only useable for sinage.

There is however the Hisense A5C phone with Color E-ink Display now on the market and it features a decent refresh rate.

https://forum.xcsoar.org/download/file.php?id=1113


If interested check out https://goodereader.com/blog/ for more info on what's coming out for e-ink.

Not affiliated, just a fan.


Waveshare e-ink displays are good for small DIY projects, but not more than that due to questionable reliability over long term use, but I'm glad they exist and they have good documentation.

Also, since the refresh rates are limited it's not like we can build ourselves a nice external large e-ink display for our reading pleasure and for the sake of our eyes.

There's a need gap for 'Affordable E-Ink large external displays'[1], last time we discussed about it here it was pointed out that the likely reason for we not having such displays are due to IP.

[1]https://needgap.com/problems/43-affordable-e-ink-large-exter... [Disclosure: It is my problem validation platform].


I hope that one day truly large scale e-ink systems become somewhat affordable. I think it could be revolutionary for architecture.

The appearance of buildings would no longer necessarily be static.

More generally, I believe that the extreme minimalism, "tranquility" (or blandness) and simplicity of more contemporary styles may some day become unpopular.

So I expect that we will see trends in the opposite direction eventually. More colors. Maybe a changing facade with e-ink. Rather than simple, boxy shapes, more intricate and more organic shapes. Large-scale 3d printing could make the use of such forms more practical.

I also expect to see architecture that is more dynamic in that it will automatically reconfigure itself in response to weather changes or the day/night cycle, winter/summer, etc.


Not directly related but there's an awesome "Open Book" project which is an open source hardware e-book reader [1].

[1] https://github.com/joeycastillo/The-Open-Book


How difficult would it be for a maker type to cobble together a portable vim editor using one of these?


The 7-colour version doesn't support partial refresh and has a 15s refresh time (~0.067Hz refresh rate), so you'd want to be a really confident touch typist.


Mind, the black and white e-ink screens would still work for this.


Sounds like it's time to learn ed.


ed echoes back the characters you input as you type them. This display would not be able to do that.


Put a one or two line black and white LCD on the bottom to show your ed-like commands, with the e-ink just showing the results of edits.


Thanks...


The Freescale i.MX508 controller can do 8fps. It seems completely capable of displaying vim, but is monochrome. Here’s a video:

https://m.youtube.com/watch?v=0DVlGZ3_d3Q

I’d love one of these with a full keyboard, wifi and enough of a terminal emulator to ssh somewhere.


From a decade ago. Seems odd how this tech has so few applications.


The small sizes, extreme update times, and high prices make it very noncompetitive with LCD.


I was chasing down this route a while ago with a Waveshare touch screen and a RPI3. I was wiring stuff up on a breadboard and was so stoked when things worked. The next level is that you send a schematic into a custom circuit board company and they send you back a PCB. The future is that we custom print open source PCB designs, solder our RPIs and Touch Screens on and bam we have custom brewed machines.


As an alternative approach, I mounted my 2012 Kindle PW, a raspberry pi, and my split keyboard (diverge 2) on a folding guitar stand.

And I mean, it works: https://i.imgur.com/FNbKA0b.jpg

Vim certainly makes the latency tolerable.


Not e-ink, but you can get a RasperryPi case with a built-in display along with battery pack. Pairing with a 40% keyboard gives a nice, portable environment.


Great video on these sorts of displays, what they're capable of, and perhaps some inspiration for any hobby projects: https://www.youtube.com/watch?v=MsbiO8EAsGw&t=617s


Anyone know how tolerant these are of UV, how long will it survive in frequent direct sunlight?


I don't know about UV itself, but the spec sheet on my 7" Waveshare eInk display says to avoid direct sunlight and extreme heat.


Attempted to look at the datasheet. There is no link, there is an image that says "user manual" and "dev resources" but it is not clickable. There is a note that says "Resources for different product may vary, please check the wiki page to confirm the actually provided resources."

ok, i clicked the wiki link: www.waveshare.com/wiki/5.65inch_e-Paper_Module_(F)

"There is currently no text in this page. You can search for this page title in other pages, or search the related logs, but you do not have permission to create this page."

so, not really hobbyist friendly


Is it just me or should this be four color CMYK like a regular printer?


Turns out that e-ink displays typically don't mix colors this way. In order to get multiple colors in a single display, they use sort of colored-balls of various densities suspended in a fluid. Then, using the known viscosities of the fluid in the capsules, they can vary the charge of the electrodes very quickly to sort of _drag_ a color up to the top.

But when you do this, you're dragging a _single_ color.

_All_ the colors are in the capsule, but you can only truly pull a single one at a time, a true pigment-like mixing isn't possible. If you pull the Cyan up, you're necessarily losing the Magenta, for example.

If you had a high enough resolution addressable grid, you might be able to put the pixels close enough that you couldn't tell, but you'd still be basically doing sub-pixel color at that point, not truly mixing the various colors at the base level.

Maybe there are other e-ink displays doing something else, but all the ones I've seen are doing some form of this approach.

Here's a fascinating video on how these displays work, and how you can modify the firmware of the driver to get faster refresh rates (with an increased risk of burn-in). https://www.youtube.com/watch?v=MsbiO8EAsGw


An area of research I've heard a bit about for next gen e-paper displays is to use electrowetting[1] which is a different approach that looks intersting

[1]https://en.wikipedia.org/wiki/Electrowetting#Applications


Oh, fascinating! This looks really interesting!


Interesting question.

My understanding is that modern printers actually mix those four different inks together on the page to achieve a wide range of colors. That isn't possible with a display where colors have to remain within their own separate (sub)pixels and can't actually mix together.

With a high enough resolution that might not matter, as your eyes would be unable to discern individual subpixels, but this display is only 600×448, and that's with only one subpixel per pixel. (A CMYK display would need 4; maybe slightly less depending on subpixel layout.)

Furthermore, modern sRGB displays can output 255 different brightness values for each subpixel. This display can only output 7 values for each pixel. That further reduces the number of possible colors which would be possible in a CMYK subpixel-based display.

Provided all those issues could be solved though; maybe it would work? There could be other considerations I'm missing. (E.g. Can subtractive color mixing even work with subpixels in the first place?)


Hm, I think the challenge is the pixel density is rather low, and unlike ink you don’t get any ink mixing.

Good printers are 600dpi, and 300dpi is passable, but this thing is 600x448 pixels on 5.65inch screen.

I think when pixel count is low, using rgb is more efficient.

I’m not an expert in any of this so this is just guesswork.


I did NOT expect this to be under US$100. Definitely going for low power with SPI interface, but I don't get their refresh claim. SPI tops out around 1MB/s... 600x448x7 is ~235KB or 4 fps at 1MBps... but 15fps? That'd be 7MB/s, which is nigh impossible on SPI.

EDIT: 15 SECONDS PER FRAME, not 15fps. Thanks everyone for pointing that out. Still, amazingly cheap ... and almost no standby current after programming.


> FULL REFRESH TIME 15s

That's 15 seconds per frame, or 0.067 fps.

That refresh rate is fine if you're using it to show the price of a rack of clothing, or various sensors - but you're not going to get smooth-scrolling text with it. The low-power interface is for those same battery-backed retail signage applications, where you're driving this, the microcontroller, and the wireless receiver with 3.7v from a coin cell.

Glad to see these becoming available for consumers and hackers! They've been hard to come by for years.


Or a "magic mirror" showing weather, calendar, time: you know, hours and minutes only :).


"Magic mirrors" don't work with e-ink since they require a lit display to shine through the mirror.


Good point. I suppose it just becomes a display then, rather than mirror — but with similar data.

More like the ubiquitous readouts in the "2001" Discovery ship.


I read the spec (column "FULL REFRESH TIME (S)") as saying 15 seconds per refresh not 15 refreshes per second. So 4 frames per minute which falls well within your calculation.

edit: Fixed to be 4 frames per minute not 4 frames per second.


Wouldn't that be 4fpm (frames per minute)? Which is no problem for signage, but not really practical as a secondary display...


Yes, my bad, it'd be 4 frames per minute.


It's seven color, not 7-bit. Also there might be just a "set color" command followed by 1-bit pixel data instead of a 4-bit pixel representation, or something.


I have a three color model from waveshare, and the way it works for it is you have to send a black and white bitmap, followed by a color and white bitmap. It's possible for these guys you need to repeat that five times.


I think its actually 15 seconds per frame, not frames per second


600x448px resolution makes it very limied for most applications. And it's too expensive to be used as a tag in a store.


Havent looked into this much- What is the maximum 'refresh' rate you can get out of something like this?


For single or double-color displays, you can do pretty decently. This Applied Sciences video on YT goes over what's possible. https://www.youtube.com/watch?v=MsbiO8EAsGw


The page says 15s.


That is what the page says, but can that possibly be right? I know e-ink tends to have very low refresh rates but taking a full 15 seconds to redraw seems excessive. I have found sites like this often have pretty obvious errors on them, is it likely this is correct or a typo?


E-ink is commonly used in signage where it won't need to change again for a week or more. 15 seconds is fine when your required average refresh time is measure in days.

I am really looking forward to the day when high refresh rate e-ink displays are common. The B&N Nook from about 8 years ago could be modified to successfully play flappy bird at about 10hz, but it was pretty ugly to use, requiring a black/white full clear of the screen to zero out the image every 30 frames or so.


That's actually not too bad for a multi-color e-ink display. The last color e-ink display I looked at had an even longer refresh interval.


My understanding is that the refresh time tends to increase significantly with the number of colors displayed.


Some months ago I saw a larger one that took half a minute of cycling through different states to fully display the final image. So 15s seems reasonable.


15 seconds doesn’t make sense for a handheld reader. Are there other scenarios where it does make sense?


Event specific signage such as 'Donner Party' in Conference Room C could be useful for many hotels and convention centers.


Information displays in retail.


I think colored ones typically change the colors in sequence, so it seems like that could be correct.


> Suitable For Price Tags, Asset/Equipment Tags, Shelf Labels, Conference Name Tags...

Maybe it's just me, but this seems quite expensive for a price tag. It also seems quite large for a name tag. I get that eink is useful in general for these cases, but this doesn't seem to be the best example.


What I really would like is a touchscreen version of this. I think the idea of a "panel" is amazing, but I'd like either a touch overlap or touch screen built in.

Anyone know of any e-ink with touch built in? can be black and white.


The reMarkable (https://remarkable.com/og) has a touch screen and runs Linux. Supposedly it's possible to run generic desktop Linux distributions on it as well.



The Amazon Kindle has a touch e-ink screen. You can use it to read books (mobi format) or browse the web (albeit in a very limited fashion - but I use it to browse HN and works fine).


I guess I should have been more specific, I meant one I could modify/make a custom app for/what ever.


I've never seen a stand alone item that included a touch layer. I think you're stuck repurposing another device to pull this off.


Nook Simple Touch. Rootable, then you can Android it.


I use my Kindle as a dedicated Reddit and HN machine before bed and it is pretty great.


Are there any alternative e-ink displays with lower screen refresh time? 15 seconds is a bit much. Or at least one that'd allow partial refresh? Not necessarily with color.


Who knows how to reasonably get power to stuff like these on walls with unobtrusive cables? Anyone have any arrangements at home that make these look nice or if not, unnoticeable?


- Pull power inside the wall. Drill a hole on top, another one on the bottom, use one of those magnetic cable pullers. Wires for 5v requires two tiny holes in drywall that's easy to patch later. There's also pretty kits made for TVs, but those require bigger holes (for HDMI, power, etc).

- Pull power from the room behind the wall. Maybe it's more out of view here.

- Place it next to a door, remove part of the frame, run wires inside the door frame.

- Cable channel exists in many different shapes and sizes, not only the boring box ones.

- Go the opposite route, why hide your cable? Make it stand out. Like those wall lamps with a brightly coloured / patterned cable hanging in loops down the wall. Turn it into wall art.

You can find some pretty wall mounted tablets in the homeautomation and homeassistant reddits :)


Thank you!


There is flat cable that you can mud and paint over, usually only good for cables that don't need shielding such as power cables. Data can be sent wireless using an esp32 on the receiving end if you don't already have that capability. There are also cable covers that look like molding.


Thank you!


Don't think about making anything remotely real time as the full display refresh takes around 15s and there is no partial refresh available.


Does anybody know of a decent micro controller that could be paired with one of these on the form factor/scale of a Kindle?


Are there any e-ink displays that are touchscreen? I did a whole lot of searching and couldn't find any.


Both the Onyx Boox Max Pro 2 and 3 have a 13.3" e-ink touch screen and run Android. On my Boox Max Pro 2 when in monitor mode (HDMI input) however the touch information is not forwarded to the host PC when connected with USB. I guess in theory an android app could do that though.


Like the Kindle? I’d imagine the tech exists somewhere.


Not the Kindle. Looking for a touchscreen e-ink display I can use with my Raspberry Pi


Clearly it's possible to manufacture such a thing, but I haven't seen any available for sale (as a stand alone item) that have a touch layer.


It's still 3x as expensive as an LCD display of the same size. The LCD display has full color, too.[1] The E-Ink display offers only 7 faded colors.

[1] https://www.buydisplay.com/5-inch-lcd-screen-tft-module-800x...


They're not competitors.


Sunlight readable though.


Never used a b+w monochrome display before? I remember the non color iPods were great in the sun.


15s refresh time. Not bad I guess for certain applications.


I wonder what the refresh time on this looks like. I recently finished a project with a red/black/white e-ink display, and the docs for it listed a worst-case refresh time of up to 14 seconds.


The docs say 15 seconds per refresh.


i would like a laptop with four of these. I arrange my xterms that way anyway.


I just ordered it.




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