Apple's 3G iPhone will add a proximity sensor

The iPhone 3G added a third sensor near the earpiece, which is still used for detecting the distance from the face. The first-generation iPhone had two sensors in this position: one for sensing external light to instantly adjust the screen brightness, and the other for detecting distance, turning off the screen to save power when the face gets close to the screen during a phone call. However, in actual use, the performance of this second sensor wasn't perfect. Therefore, Apple added another sensor with the same function to improve the accuracy of face-distance recognition. As a result, Apple specifically requested that third-party case manufacturers increase the area of the opening at the top earpiece to ensure that the sensor is not covered.