E-paper hacking: fastest possible refresh rate

yeah I believe that was the only option for older / cheaper displays. I recently got a kindle for a present and notice that when it can, it will try to refresh the screen as little as possible. For example, when you press the top of the screen to bring up the settings, only the top cycles, and then the same when you tap below to get rid of the settings. To that end, I would be interested in watching some high-speed camera footage of the displays just to see the gears turn. I’ll have a look round and edit this comment if I find any. e: found one. [link] also a video from an engineering channel that normally gives good insight into these things, I have watched it yet so it may not be great, but Applied Engineering normally brings some interesting material. [this video]

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). [this video]

I built an e-ink clock recently. E-ink has two downsides; the datasheet says that the display will be damaged if it's refreshed more than every 3 minutes (I ignore that and refresh it every minute, so we'll see if it lasts) and the black/white/black refresh cycle is very visually distracting. Having that thing in the field of view just doesn't work. Both of these issues can be gotten around with a different refresh algorithm, but of course the datasheet doesn't include any of them. The vendors regard their refresh logic as proprietary and so you have to spend months trying to figure out what will work, like this: [this video]

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: [this video] 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.