[Ironballs]

The Paperwhite isn't a backlit display.

The LEDs in the Paperwhite Kindles do not shine light directly in the eyes: the leds shine from below the screen towards the top end of the screen. As it exits the LEDs, light is reflected inside a light guide from which it exits towards the display from specific holes, much like a leaky fiberoptic cable[1].

The directionality and position of the LEDs, and the existence of the light guide, are precisely the differences which make the Paperwhite unlike a backlit display.

[1] http://www.nytimes.com/interactive/2012/12/26/technology/lig...

[ce4]

That's the same with smartphones and tablets.

For the sake of simplicity and to keep it as thin as possible, they use edge-LED lighting with a diffusor layer to spread the light evenly.

[DrStalker]

Are there any smartphones/tablets that have the light hit the display surface from the front and then bounce off like the kindle does? I thought they all either used a backlight shining through the display from behind or were an array of tiny little light sources (depending on the screen technology used) - either way the light is being broadcast direct from the source to your eyes; not hitting a surface and emitting diffuse light out.

[seba_dos1]

Old monochrome reflective LCDs used that, but smartphones and tablets are almost always using transmitive screens with backlight (sometimes transflective, like on Nokia N900, but reflective properties are only usable in very bright sunlight).

Kindle Paperwhite however has 100% reflective e-ink screen plus set of LCDs that shine through the light guide layer above the screen. Some people think that makes it better than transmissive LCDs - that's why using Kindle Paperwhite instead of iPad in this test would be much more insightful, as sleep-disturbing properties of transmissive, blue-tinted LCDs are nothing that wasn't known before.