How does e-Ink actually work?
In: Technology
You make millions of tiny bubbles that act sort of like pixels, like a sheet of microscopic bubble wrap. Now you fill every bubble with fluid and some charged black ink particles all suspended in it. Then you lay a grid of electrically-conducting material underneath it the sheet of bubbles, aligning with the little pixel capsules.
Now it’s just applying electricity. If you send a negative charge to one little square on your electrical grid, it’ll attract all the black particles down inside that bubble, and let the fluid up to replace the space, so you’ll see a blank space. But send a positive charge to the pixel on your tiny electrical grid and it’ll repel the black ink particles in the bubble, pressing them up against the screen. Now you have what looks like a filled-in black pixel from on top.
The little things stay charged until they get a different charge (well, they fade very very slowly, over weeks usually), so that’s why epaper stays showing the same thing even when you turn it off, until you send them new charges.
That is also why epaper displays are “slow” to change and respond, because there are literally tiny physical bits of black ink that have to move through a liquid every time the computer tells the “pixel” to change.
(There are fancier versions that use two grids, one on each side, and even black and “white” ink to move around because that way it can respond faster, but that’s more complex to explain and works the same way.)
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