I visited my mother-in-law the other day and she is very skeptical of modern, digital technologies. Partly she distrusts the physical properties that may cause negative radiation but also the hypnotic effects of many screens. But my ereader fascinated her immensely. So compact, long battery life, versatile but I could only moderately explain what makes the screen so special. A new attempt.
The electronic paper of an ereader does not emit light but works just like a paper book. It receives light from its surroundings and reflects it. So the light and dark parts of a page are physically present and therefore so sharp and quiet for the eyes. No flickering caused by the frequencies of refreshment.
But an ereader also emits light, right? I myself like to read in the dark and so use the ereader as a sort of flashlight. But that light does not come from the screen but they are LED lights in the side of the screen. So no light comes out of the screen but the screen is illuminated.
Workings of digital ink
The screen of an ereader is a grid just like a normal screen of computer or mobile. But the small elements in the grid become black, gray or white. An electric current causes the pigments in the tiny sphere to swap places.
This is also the reason that after the page is built, the ereader no longer uses power and the ereader just shows a page or image even if the device is turned off. With a difficult word, the spheres are bistable.
So the page of an ereader is physically present and has a high contrast. With a magnifying glass, or better a microscope, you would be able to see the white and the black. That's also the reason you can read in sunlight and at a reasonably wide viewing angle. Next to that, electronic paper and digital ink are low power, very compact and durable.
I myself have a Kobo Clara and the screen has a resolution of 1448 x 1072 pixels. That means that it has one and a half million pixels over a six inch screen. In practice it means you don't see the actuals pixels and the fonts really look smooth.
Want to see more, check out this video explanation and tour: