[Brian_K_White]

Eink works by physically moving bits of material around in a viscous liquid. You can refine that (use stronger electric field, stronger reacting pigments, less-viscous fluid, thinner layer for smaller travel distance) but never get around it.

[thelazyone]

That is true, but this doesn't pose a theoretical limit to a 30 fps monitor.

I suspect that the current technology works by "setting" in place whole regions of the screen at once, and that this kind of process is inherently slow. Maybe in a (not so distant) future it'll be possible to have individual pixels changing, in a similar way as an mp4 doesn't update all the image when not necessary.

Or not. So many technologies just embank somewhere and find their niche.

[Brian_K_White]

They do that already, and it results in ghosting and leftover artifacts.

It's all tradeoffs, improving one number only to a limited extent and only at the expense of other numbers. Ie, faster action at the expense of worse image. No free lunch or getting around it by handwaving 'advancement'.

[thelazyone]

If the update was truly pixel based there should be no ghosting/artifact whatsoever. Looks like global refreshes or cleanup are still relevant, while ideally each pixel could be completely independent.

Trade-offs are a problem, but in this case i don't see any physical reason for this to be a theoretical trade-off. More like a limit of the current technology.

[arp242]

It is pixel-based, it just doesn't result in perfect updates. I'm not entirely sure why this is the case: maybe the power is too low (as a trade-off between speed and accuracy), maybe clear a cell affects neighbouring cells, or maybe something else.

E-ink displays are hardly new and lots of people have been thinking about/working on the slow refresh rates for over 2 decades. Do you really think that anything you can come up with on HN in 5 minutes without any knowledge of the tech is something people hadn't thought of before?

[thelazyone]

There's a big difference between having a solution and point out that there is no theoretical hard trade-off. ^^"

[mdp2021]

> If the update was truly pixel based there should be no

Why? Nobody said that the cell is "reset". The cell is modified. The resulting state depends on the former state. This causes ghosting.

To achieve what you are suggesting, the procedure would be e.g. to first set the pixel black, then white (reset to a base state), then the greyscale value of the intended content. This would slow down rendering dramatically, and make regions flicker.

And, note, this may be something that some "EPD waveforms" do - but there are tradeoffs... E.g. Fast? Ok, lose the greyscales. Detailed? Ok, get lots of flashing at update. Mid-way? Ok get some degree of ghosting.

[thelazyone]

That's a fair point, well made. In that case --- yeah, we just have to wait and hope for better solutions/materials for our screens!

[Brian_K_White]

It is pixel based logically, which comes out only imperfectly physically. Believe what you will.

[thelazyone]

Yeah, the other replies were pretty convincing about that point.

[mdp2021]

> it'll be possible to have individual pixels changing

EPD displays already have that capability.

When you modify the dots you use a modality that is sensitive to former states. What happens in full-screen refresh is a cleanup to redraw on the best former state for the cleanest output.

[thelazyone]

Even local refreshes however are somehow rectangle-based, no?

Which means that the resetting operation kinda works globally anyways, masking out everything between the xmin, xmax and ymin, ymax.

I'm really speculating here, but this was my impression every time I saw individual areas changing without a gobal refresh.

[ambyra]

I wonder if it would be possible to layer screens to double refresh rate.