How to kill your iPhone with the wrong case

May 15, 2008

iPhone Proximity Sensor
A lot of the magic of the iPhone is that things just work. Intuitively. A great example is during a call — when you bring the phone to your ear, the touch screen and display shut off automatically, to keep you from hanging up or dialing with your face. When you pull it away, the screen lights back up and the touch screen is activated again. All automagically.

Of course, that auto-magic has some real technology behind it — there is a little proximity sensor that both emits and detects an infrared beam — during a call, when an object (such as your ear) comes near it (within an inch or so), it reflects the beam back to the detector and shuts down the screen. When the reflection stops, the screen comes back on.

The proximity sensor is hidden under the glass just above the speaker hole — the overly-contrasty image above shows the rough location. You can see the actual sensor on this disassembly photo from iFixit.

Amazingly, nearly a year after the introduction of the iPhone, there are still a lot of cases being sold (even in places you think would know better) that cover up the proximity sensor with opaque material. Put one of these on your iPhone, and you too can dial with your face, hang up with your cheek, and get frustrated by not being able to punch in digits during a call.

Worse, there are more than a few rumors out there that if you leave the proximity sensor covered long enough, it can “stick” and just fail to work altogether — even if you take the cover off. If it sticks in the “screen off” position, you’re done until you get your phone repaired.

The moral of the story is be careful of your iPhone case — if you try a new case, double-check that the proximity sensor still works as it should, and if not, take it back and get a different one.

If you’ve found a great case that does work properly — or have a case horror story — share it with us in the comments!

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5 Responses to “How to kill your iPhone with the wrong case”

  1. Trent on May 15th, 2008 5:10 pm

    Thank you.

  2. Chuck Lawson on May 16th, 2008 1:34 pm

    de nada

  3. Ajay on June 24th, 2008 2:54 am

    I have had a Invisible Shield on my iPhone for some time now, and only recently it seems to have “stuck”…. not sure what to do as I have tried numerous reboots of the phone and still nothing. I assume that if it was broken wouldnt it think that the sensor is alwayss covered and when makign a call, the screen would just go black?
    It looks like something im going to have to consult apple about? hmmm what will they do when they see a unlocked/jailbroken iphone :S

  4. Chuck Lawson on June 24th, 2008 8:20 am

    Apparently the sensor can fail in either mode — either fully on, or fully off…

    It’s a safe bet that you don’t want to go to the Genius Bar with an unlocked or jailbroken iPhone. You’ll want to do a full restore and take it in. They’ll probably replace it with a new (refurbished) iPhone, so you’ll need to jailbreak it all over once you get it home anyway.

    Good luck! From what I understand, they end up replacing a lot of these due to badly designed cases, so they’ll probably just swap you without saying much other than warning you about cases.

  5. Surita on June 7th, 2009 12:12 pm

    Thanks, that clears things up pretty well for me but knowing that it was my new leather case causing all the new strange behavior, I cut out the material covering the sensor leaving one problem. My case folds over into a wallet when not in use so my question for certainty is, will protecting my iPhone with any cover other than a back piece just cause the iPhone internal dammage in the long run? I’m sure you have already answered this, but as I said for certainty.

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