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:
- The HTC screen protector for the HTC Mozart (the phone involved each time) has small cutouts where the proximity and light sensor are which look likes UU. The little tab between the cutouts can get caught on things and lift. If you cut the lift tab off to make a single wider cutout, the problem is fixed.
- If your screen protector does not have cutouts, and you cannot clean under it to get it to sit flat on the glass, then it is time to replace the screen protector. That will fix the problem.
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.