
E Ink Waveforms are a closely guarded secret - kozmonaut
https://goodereader.com/blog/e-paper/e-ink-waveforms-are-a-closely-guarded-secret
======
userbinator
Is it really "closely guarded", or "worst guarded"? Anyone with a logic
analyser and a few hours can probably figure it out easily enough... and some
have even gone _beyond_ what the official controllers can do:

[https://hackaday.io/project/11537-nekocal-an-e-ink-
calendar/...](https://hackaday.io/project/11537-nekocal-an-e-ink-
calendar/log/72153-can-you-get-32-level-grayscale-out-of-an-e-ink-display)
(previously discussed at
[https://news.ycombinator.com/item?id=16140284](https://news.ycombinator.com/item?id=16140284)
)

More research from others:

[http://essentialscrap.com/eink/](http://essentialscrap.com/eink/)

[https://news.ycombinator.com/item?id=11894613](https://news.ycombinator.com/item?id=11894613)

[https://www.eevblog.com/forum/microcontrollers/interfacing-e...](https://www.eevblog.com/forum/microcontrollers/interfacing-
epd-\(e-ink\)-display-from-kindle-anyone-tried/)

~~~
sofon
The waveforms will all likely be disclosed in their patents too:

[https://patents.google.com/?assignee=E+Ink+Corp](https://patents.google.com/?assignee=E+Ink+Corp)

Certainly a number of drive waveforms and the basic concepts are presented.
There are likely implementation subtleties or specific configurations that are
not explicitly disclosed.

You can probably figure out a lot about both the implementation, and
motivation by digging through the patents.

~~~
amelius
Yes, it would be quite stupid to guard the secret and not patent it. So the
title of the article doesn't make much sense.

~~~
wingspar
That’s done all the time. Called a trade secret.
[https://wikipedia.org/wiki/Trade_secret](https://wikipedia.org/wiki/Trade_secret)

~~~
antt
A trade secret that can be reverse engineered by a tinkerer with an
oscilloscope in an afternoon.

This is more or less the type of situation patents were invented for: a simple
invention anyone can copy once it's invented, but difficult (I assume) to
invent in the first place.

~~~
kosievdmerwe
Or expensive to invent.

It's why I don't like most software patents, but why I think codecs,
especially the modern ones, should be patentable. They're complicated
engineering challenges requiring you to make numerous tradeoffs and I feel
that just because the result is an algorithm doesn't mean that it shouldn't be
patentable.

Other software patents I'm more dubious of, but I feel comfortable saying
H.264 should be patentable.

~~~
amelius
Totally agree. However in many cases, the main technology is invented at
universities with public funding. Also, codecs are a means of communication,
and I don't think it should be patentable because it can cause problems once
everybody settles on a single standard. See the MPEG nightmare, where
professional cameras have a license attached to any movie shot with them.

------
chaoxu
Recently, I brought a Dasung paperlike HD to use as a monitor. (crazy
expensive, prob should've spend money elsewhere...) I thought some things were
impossible with eink, but it proved me wrong. (video in a reasonable fps)

It has a few different ways of display. For example: Floyd–Steinberg
dithering: essentially only black and white with dithering, and the speed
pretty good. A16: uses 16 shades of grey, but the speed is horrible for moving
images. So I wonder if a mix of the two can do much better (e.g. moving
objects using floyd-steinberg until it stops moving)

Before doing that, I need to know the exact limit of eink. Are some operations
slow because the microcontroller or because it is the limit of the display
module itself? This article shows such a question is not that easy to answer
using the openly available information.

Also, I'm interested if there are algorithmic problems to be solved in this
space. (I do research in theoretical computer science). If you are in NYC and
knowledgeable I'm very interested to chat (I know little, but I have the
monitor you can play with).

~~~
tigershark
Why would you use an e-ink display for videos? The main advantage is the low
power consumption because it needs power only to refresh, using it for a video
it will negate that advantage and draw _much_ more power than a traditional
display with an awful image quality...

~~~
chaoxu
1\. Currently, I use it for writing code and reading papers. However, I still
want the monitor to be a good enough drop-in monitor for things I need to
occasionally do. For example, I need to switch to a browser window to check
what was that error I'm getting.

2\. Visual snow syndrome: Many had their first experience of visual snow after
staring into the screen for too long. People who believe in that is the cause
of visual snow would want a screen that does not emit light.

~~~
mrob
What exactly about emitted light is a problem? Light doesn't carry a memory of
how it was generated, so it must be some difference in some measurable
property, e.g. brightness/contrast/color spectrum/flicker/polarization, or the
way these change at different viewing angles. If you know which attributes are
important then you might be able to match them with an emissive display.

~~~
ben_w
Emissive displays don’t generally match the brightness of their surroundings;
even with automatic adjustment, most are physically incapable of being as
bright as a newspaper in daylight, and many cannot be as dim as a newspaper
lit only by one of those small book-reading lights without being switched off
entirely.

There’s also the spikey spectrum, which looks the same consciously but I’ve
seen claims [1] that is messes with our circadian rhythm.

[1] I lack the skill to tell if this is real science or neo-mystic woo.

~~~
Avamander
I think most people are forgetting that LED backlights are controlled usually
using PWM which flickers, fast, but still flickers. I haven't found any
research about how it might affect humans. I suspect it would be better if no-
flicker current-controlled LED backlight was used instead of PWM.

~~~
diffeomorphism
According to notebookcheck only about half the devices they tested use PWM:

[https://www.notebookcheck.net/Why-Pulse-Width-Modulation-
PWM...](https://www.notebookcheck.net/Why-Pulse-Width-Modulation-PWM-is-such-
a-headache.270240.0.html)

It seems to be well known that it for low frequency PWM it causes headaches
for some people, so I would expect that there is at least some research in
that direction. That said, it seems to only be a problem for few people and
only for very low frequencies.

------
guitarbill
Ben Krasnow (Applied Science on YouTube) did some research into driving e-Ink
displays, and he made some similar observations:

> All of the lookup table information has been removed from this datasheet,
> because the industry thrives on secrecy or something

Highly recommended, as usual for him it's a great video/write-up:

* [https://www.youtube.com/watch?v=MsbiO8EAsGw](https://www.youtube.com/watch?v=MsbiO8EAsGw)

* [http://benkrasnow.blogspot.com/2017/10/fast-partial-refresh-...](http://benkrasnow.blogspot.com/2017/10/fast-partial-refresh-on-42-e-paper.html)

~~~
therein
Yeah, his series is really great and it made me realize the FW flashed on
these CARTA panels are actually nothing but the raw waveforms themselves.

One thing that I want to note is that while their documentation might be
closely guarded secret, the actual waveforms are actually available out in the
open.

For instance here are the raw waveforms for one of the latest Carta generation
e-paper panel:

[https://github.com/canselcik/libremarkable/blob/master/refer...](https://github.com/canselcik/libremarkable/blob/master/reference-
material/epdc_ES103CS1.fw?raw=true)

    
    
      ~ hexdump -C epdc_ES103CS1.fw | head -10
      00000000  34 88 c4 7c 01 2d 01 00  dd 09 00 00 07 06 a4 00  |4..|.-..........|
      00000010  03 58 21 1d 3c ca 01 85  02 00 00 00 40 00 00 fe  |.X!.<.......@...|
      00000020  47 00 00 01 00 04 0d 00  ff fc 00 00 00 00 00 54  |G..............T|
      00000030  00 03 06 09 0c 0f 12 15  18 1b 1e 21 26 2b 30 28  |...........!&+0(|
      00000040  00 00 00 00 00 00 00 08  3e 05 00 00 00 00 00 e8  |........>.......|
      00000050  cb 06 00 00 00 00 00 c8  8d 0a 00 00 00 00 00 a8  |................|
      00000060  4f 0e 00 00 00 00 00 98  00 00 00 00 00 00 00 a0  |O...............|
      00000070  65 00 00 00 00 00 00 a8  bc 00 00 00 00 00 00 b0  |e...............|
      00000080  0b 01 00 00 00 00 00 b8  5a 01 00 00 00 00 00 c0  |........Z.......|
      00000090  aa 01 00 00 00 00 00 c8  31 02 00 00 00 00 00 d0  |........1.......|

------
Roritharr
E Ink seems to be one of the technologies that is hampered solely by patents.
It's too sad that we're only going to get major innovations in e ink tech in
15-20 Years...

~~~
reustle
Would/could/do Chinese manufacturers ignore those patents? Are they not able
to sell abroad if they do?

~~~
jfim
Importers would likely get their shipments seized. It's not illegal for
manufacturers to export their goods out of China, but US customs doesn't look
too highly on importing goods that contravene on registered US IP.

Small time shipments are unlikely to be looked at (eg. if someone buys a
single electronic ink display off of AliExpress), but someone actually
importing many displays for resale would likely eventually get caught.

~~~
dev_dull
Honestly how would you even know if the e-ink displays infringe on IP? I can’t
imagine them doing anything.

~~~
extrapickles
A patent gives you a monopoly which makes things easy.

You occasionally search the market for products that contain your tech (in
this case eink), then look in your records to see if they bought/licensed from
you.

~~~
billfruit
But is it that infringement can be proven only by a court? So can US customs
do any thing in such cases, even if we assume they have the competency to
judge if a particular import violates IP.

~~~
toast0
They file a case, and ask for a preliminary injunction. And once that's
granted (which is likely), they take that order to customs, and customs will
start looking for those devices in shipments from your supplier or to you.

------
chx
Some info
[https://hackaday.io/list/35814-e-paper](https://hackaday.io/list/35814-e-paper)
here and especially from the links provided, everyone is working from
[http://essentialscrap.com/eink/waveforms.html](http://essentialscrap.com/eink/waveforms.html)
and
[http://spritesmods.com/?art=einkdisplay](http://spritesmods.com/?art=einkdisplay)

And [https://hackaday.io/project/21168-fpga-eink-
controller](https://hackaday.io/project/21168-fpga-eink-controller) has an
FPGA doing waveforms by extracting them from existing firmware. So while it
might be a closely guarded secret, just replicating it is possible.

------
ehead
In my experience, memory LCD has been a better technology to work with:
[https://www.sharpsma.com/sharp-memory-lcd-
technology](https://www.sharpsma.com/sharp-memory-lcd-technology)

No crazy +/\- 40V lines, no external driver circuitry, and extremely low
power. Not as low power as E Ink, but since you don’t need to drive wacky
voltages, your power budget math will come out the same or better.

~~~
robin_reala
I’ve never seen one in real life. How are the display characteristics compared
to eInk?

~~~
ehead
If you’ve ever seen an OG Pebble, you’ve seen that display. It looks like a
better resolution gameboy display. Very little space between pixels.

Some models are different, though, and basically turn into a mirror when their
pixels are turned on, rather than become matte black.

Adafruit sells a dev board for 25 bucks. Perfect for low power wearables, much
better than E Ink.

~~~
ByThyGrace
Is this tech relatively new? Is it merchandised as "memory LCD"? I would like
to know when searching for e-reader displays in the future.

~~~
dbuder
It is not new and rarely mentioned in advertising or product information. The
memory LCD I've seen are too small for a normal e-reader but if you are doing
a large production run you can have something custom made.

------
DiabloD3
Unfortunately, what the article described sounds a lot like a thermometer
coded delta-sigma DAC or other similar design.

How these are constructed and used are well known, and they're probably lying
about "closely guarded" to make sure people don't realize it is just a clever
usage of an off the shelf part, and none of the magic is in-house.

------
olebrown
Where would one anonymously publish an E-ink data sheet with waveforms if they
had one?

~~~
kozmonaut
You can send it to me.

~~~
olebrown
Are you author of the linked article? What's contact info?

~~~
kozmonaut
use the contact form on the website for the linked article.

------
Vekz
Here is a teardown of a 13.3 high perf E-ink monitor I did a few months ago:
[https://kevzettler.com/2018/02/11/dasung-paperlike-pro-
teard...](https://kevzettler.com/2018/02/11/dasung-paperlike-pro-teardown)

The post identifies some on market E-ink display components and discusses the
design of a proprietary display driver.

~~~
rwmj
_" On closer inspection all the chip components have had their labels
chemically peeled off to prevernt reverse engineering."_

Wow, I've never seen that. Is it a common thing? It also puts me off buying
one of these (assuming the $900 price tag hadn't put me off already).

~~~
userbinator
I've seen it a lot in Chinese electronics, and it only deters the least effort
of reverse-engineers.

Erased markings are usually a sign of off-the-shelf parts; they didn't go to
the effort of printing their own branding on them.

------
pietroglyph
The article doesn't mention this anywhere, but the "waveform" is usually a 4D
lookup table with target and previous grayscale value, temperature, and frame
number.

------
dugborkt
For extra fun for all the people trying to reverse it, the exact waveform data
changes per batch of displays. The overall strategy will remain the same
though.

If you want to see a more complete list of waveform names you could probably
go look at the gpl releases of popular readers...

------
jokoon
I wonder if eink would be really useful to make a low powered smartphone. As
long as you use software which doesn't burn a lot of power, like email and
other stuff which is designed to run with fewer cycles.

At that point I would really care for software with a minimum amount of non
fancy feature that doubles or triple battery life. If you make extensive use
of text, and don't use high resolution image or set low limits, there are
surely ways to make a more durable device.

Cheap androids are awesome, but I have no idea why they're becoming slow as
they age, and I'm sure software is always to blame. I really crave minimalist
designs when it comes to hardware and software.

~~~
gh02t
The display is only part of the story. You could save some battery life with
an e-paper display sure, but you still have the CPU and radio grinding away at
the battery. The ultra power saving mode on my Samsung phone is a good
example, it throttles the CPU, sleeps the radio aggressively, restricts the
phone to only running a few basic apps, and turns off most of the OLED
display. I can increase battery lifetime by almost a factor of 5 with that on.

An e-paper display would save a bit more, sure, but the type of display isn't
the only limitation to a low-power smart phone. You need to design the whole
thing to work together to save power; changing one component isn't gonna be
enough.

------
FullyFunctional
This is really frustrating as if you already have an FPGA (and appropriate
regulators), the controller is just redundant overhead (in every metric
conceivable). I'm glad to see at least the beginning of reverse engineering as
some of the panels (typically kindle replacement panels) are quite affordable
and even the $450 13.3" panel isn't unreasonably expensive. (An FPGA-powered
PocketCHIP-like device with e-Ink would be a lot of fun).

------
acd
Is Waveforms what is in Epsons eink controller chips?

[https://phys.org/news/2011-05-dpi-epson-e-ink-epaper-
resolut...](https://phys.org/news/2011-05-dpi-epson-e-ink-epaper-
resolution.html)

Japan display has made 600 dpi controllers.
[http://www.j-display.com/english/news/2017/20170522.html](http://www.j-display.com/english/news/2017/20170522.html)

Further been thinking of building an Eink based smartphone, the eink display
would have low power. Some kind of low power small system board running Linux
and a 4g modem. Not sure what system board to pick. Batteries should be
LifePo4 Lithium iron for battery safety. What kind of high resolution touch
based eink displays are out there which are easy to drive from a small Linux
system board?

------
nanomonkey
Anyone interested in running linux on their Kindle should check out
[http://fread.ink](http://fread.ink)

Juul spent a good amount of time working out how to read the stored waveform
configurations (different for each unit) and getting them to run at a
reasonable speed.

~~~
thomas
I'm looking for an e-ink monitor (along the lines of
[https://cloudconfusing.com/2018/09/18/e-ink-monitors-
ready-f...](https://cloudconfusing.com/2018/09/18/e-ink-monitors-ready-for-
prime-time/) ). Would this work for that?

------
etaioinshrdlu
Seems like a good use case for PID loops -- drive the pixel really hard for a
brief moment to bring it to the target value faster than might otherwise be
possible.

Seems limited only by the voltages that just end up frying parts.

~~~
tlb
For a PID loop, you'd need to be able to measure the position and velocity of
the black dots. Velocity seems very hard. You could conceivably measure the
position with a camera looking at the image, but will people want an ebook
reader with a camera sticking out in front?

~~~
etaioinshrdlu
Good point. Maybe not a PID loop at all, but rather an well tuned open-loop
controller that compensates for the natural time response of the e-ink pixel.

------
nbevans
Usually when a piece of tech is protected purely by obscurity in this way, the
tech isn't really tech. It is more likely something that a decent
programmer/hacker could figure out in a day or two. That's why they are scared
to share any info - because even just a single sentence could be enough of a
hint to a competitor in how it works.

------
coldtea
Is E Ink anything more than a marketed technology with no real purpose?

One can calibrate the brightness, white balance (e.g. Apple's True Tone),
resolution, etc of a regular LCD or OLED display so that the same amount of
photons hit your eye (and are more tightly controlled when you move the
display around) as with an E Ink display, and get better resolution color, and
saturation to boot.

Besides the idea that it was easier on the eyes was never backed by any
substantial scientific studies, it was just "but it's like paper, so it should
be" plus some manufacturer sponsored crap.

Well, there's the extended battery life I guess...

~~~
toast0
Screen persistance with zero power can be a pretty big deal. It's always nice
(ish) when my Kindle has the 'your battery is dead' screen on when I go to use
it, so I know what's going on even before I try to turn it on.

Other than that, it's hard to compare because nobody makes large monochrome
lcd displays. Monochrome is actually a feature for the intended use:
newspapers and books use a pretty limited amount of color, so you get improved
pixel density and geometry without having to split pixels into colors.

OLED won't work for dark text on a light background, and tends to be rather
expensive -- I can't imagine a Kindle sized device with an oled display for
less than $200, so that limits it to the high end models.

~~~
romed
Eizo still makes monocrome LCD monitors. They are for medical diagnostic
purposes.
[https://www.eizo.com/products/radiforce/gx550/](https://www.eizo.com/products/radiforce/gx550/)

