[youtube]http://www.youtube.com/watch?v=blMzWkHhFFw[/youtube]
The new iPhone 4S terminal bring and a new "proximity" sensor whose functionality is different from that of the iPhone 4. The change implemented by Apple is related to the Siri personal assistant that can also be used when we hold the phone to our ear, but to do this it was need to implement an infrared LED sensor. If on the iPhone 4 the sensor was only activated when we were talking on the phone, on the iPhone 4S we have a second infrared sensor that activates when we open the screen, but only if you have Siri active in iOS.
During our iPhone 4S teardown, iFixit buddy Markus noted that the new iPhone had a rather unusual-looking black component next to the ambient light sensor. We didn't make much of a fuss about it since we were knee-deep in disassembly pictures, but the little black box certainly piqued our curiosity. Now that the teardown is wrapped up, we've re-opened the mystery and made a neat discovery about the 4S: that black component is an infrared LED, and the little bugger almost always wants to know if you're nearby.
The video clip above was made by iFixIt and in it we demonstrated how the new sensor implemented by Apple works. Unfortunately, turning on the sensor every time we unlock the device requires sustained energy consumption and this will probably be felt during the use of the device.
