A new Apple patent filing discovered by BusinessInsider shows a system that can detect when your iPhone screen is smudged, and thus prevent the display from sleeping like it does when you hold your iPhone close to your ear.
Apple details that a system that measures the light coming onto the iPhone display to figure out whether the obstruction is the result of being held up to your head or from something else, such as a smudge.
The filing explains that sometimes, a smudge from your finger on your iPhone screen can block the path of light back to the phone’s sensors. As a result, the iPhone might think that you are holding your phone up to your head, and then turn off the screen, or it could think that you’re not holding your phone up, when in fact you are. Apple’s new technology can tell the difference between two types of smudges, one that blocks light and reflects it back, and one that lets it out when it shouldn’t.
To read about the patent in detail, click here.