If you look closely at a backlit kindle screen, you can see that the e-ink pixels are a decent distance behind the surface. It’s more noticeable if there are scratches or dust on the screen and you rotate the display. The surface reflects the light from the sides back to the e-ink.
IIRC, side illuminated microscopic dots on a protective cover. Light only escapes through the dots, illuminating the panel, without shining into the user.
If you look closely at a backlit kindle screen, you can see that the e-ink pixels are a decent distance behind the surface. It’s more noticeable if there are scratches or dust on the screen and you rotate the display. The surface reflects the light from the sides back to the e-ink.