It's only really visible when looking at a very dark screen with fairly high screen brightness, but is one of the few obvious signs this is a cheap device. (pocket-lint.com)
This means less precision when you have a big bright spot on an otherwise dark screen. (gizmodo.com)
A sensor is not working properly like while calling when i take out from ear it's not showing displaying still it's in dark screen for that i need to change any settings or something went wrong. (gogi.in)