As the designated "gadget geek" at home and work, I am often asked about technical problems with gadgets to see if I can help (Read as: David, please can you fix this quickly and for free as I don't want to wait or pay for someone else to fix it). To be honest, I don't mind as I am fairly good with fixing things and always like to help friends and family out. The good things you do always come back in one way or another.
I have been asked about the topic of this post a few times now. The last time was via an instant messenger session and I suggested the solution without even seeing the device. The friend who had the issue asked if I was psychic. I will neither deny or confirm this point.
Here is the problem: Every time a call comes in on the phone, the screen goes blank and I have to turn the phone off and on again to be able to use it.
And here is the cause: The phones in question had screen protectors added to stop the screen getting scratched. (Great idea. I always have a screen protector). However, in the case of the phones having problems, the screen protector had lifted on the edge in the location of the proximity sensor (see image below). So the proximity sensor is being triggers all the time as it "sees" the screen protector as a face and turns the screen off.
Finally, here is the simple solution: Fix the screen protector. This does depend a little on the type of protector:
HTC Mozart with location of proximity sensor highlighted
This was occurring on a HTC Mozart Windows Phone, but could happen on any brand or operating system of smartphone that has a proximity sensor built in.
If this happens to you or someone you know.... now you have the solution.
13-Nov-2013: We have also seen this issue with dust in the phone affecting the proximity sensor. Also sometimes the proximity sensors themselves do fail.
I have the same phone with the same problem however I have never used a screen protector.
I have seen many similar posts highlighting the same problem and although I am sure your solution would work with a 'faulty' screen protector, I have not yet seen a solution for one that does not have a protector.
Could my issue possibly be related to a faulty proximity sensor?
Yes, it is probably either a faulty proximity sensor or dust inside the phone affecting the sensor.
The Nokia Lumia 920 has a known issue with dust getting in. Can sometimes be fixed by spraying compressed air into the headphone socket.
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