iPhone 4 Proximity Sensor Malfunctions Reported
Increasing numbers of iPhone 4 users are reporting the touchscreen becoming active during phone calls when the proximity sensor would normally shut it off, leading to inadvertent button-presses. The reports are coming in with enough frequency and consistency to suspect a hardware or calibration issue with at least a particular subset of iPhones. No word from Apple yet.
The iPhone's proximity sensor uses a small infrared LED and uses the reflection from nearby objects to deactivate the touchscreen when it's close to your head. If you hold it up to an iSight or other camera that can read near infrared light, you can usually just see the glow. The problem may be in how sensitive the detector is set to be on some phones or an actual problem with the detector. So far I haven't noticed it with my own phone, if I make a call and hold a finger in front of the sensor with my finger the screen deactivates out to about an inch away.
An email from a MMi member this morning reported hearing keypress tones during calls, and in one instance his phone tried to initiate a FaceTime call while he had the iPhone to his head. There's an Apple Support thread
with forty-one posts as of the time of this writing, most with similar reports. One user says
the display activates when he rocks it from side to side.
Anyone out there seeing this?