If you your Samsung Galaxy S3 uses, then you will surely be a little eye icon to be noticed in the status bar, which now and then to flash if you heavily on the unit.
The eye icon comes from the Samsung Galaxy S3 "Smart Stay" which can be lit up the screen as long as you look with your face on it. While the eye icon blinks reviewed the Galaxy S3 sensor means whether a face just looks at the phone or not. If no face detected dims the screen.
How to switch the "Smart Stay" lock on or off, we'll show you now:
Go through the menu in the settings of your Samsung Galaxy S3 and selects the menu item "Display". Another point is lower then the "Smart Stay" mode, which can be enabled or disabled now.
If you have the problem that the smartphone does not recognize your face in dark rooms or in the dark, then this is due to the sensors of the Samsung Galaxy S3. This works in a dark room not so good and the Smart Stay mode is not activated, ie your Galaxy S3 will darken the screen after a certain time.