[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.