原帖由： Barry Gilbert ,
Your "Dark LED" is the Proximity Sensor. It is shooting out IR which bounces back and hits a receiver which tells the phone when it is next to your face. That shuts off the screen so you dont inadvertently touch and trigger actions on the screen. Right next to it is an ambient light sensor that the phone uses to automatically control the brightness of the screen to preserve battery life. My question is just over from there there is another hole in the case with an unknown function. It can be barely seen from the front of a black 4S and is invisible due to being painted on a white iphone 4s. The round hole is plainly visible in the teardown and is not in any of the previous phones.