[Windows Central Question]

After replacing the glass on my Lumia 520 double tap to wake stopped working:
Before the replacement it worked fine.
I haven't noticed any difference in responsiveness of the screen other than this.
I've tried turning the function off and on.
I've tried changing the sensitivity from normal to high.
I've tried rebooting the phone.
I've checked to make sure that the proximity sensor is working and it's seems to be fine.

[Harrie-S]

If you not used an original OEM part for the replacement than that is the reason.

[rjacs]

Thanks for answer. The glass is supposed to be original, but I don't really believe that. Can you explain why it doesn't work? How is the double tap to wake different than any other touch input?

[Harrie-S]

During normal touch input your touch is a kind of xy recorder. Your phone can determine where you touched it and than "knows" what you want.

For double touch to wake up your touch panel is however in a low energy state and needs to work together with the proximity sensor.
If you double tap your phone has to determine is it is a wake up call or not.
If you have your phone in your pocket and double tap it t will not wake up because the proximity sensor detects it is in your pocket.
)The wake up could also be done with only 1 tap but then you would often get a false wake up. So to prevent than you need to tap 2 times this reduces the change on a "false" wake up).

So the double touch is works "completely" different than the normal touch input.
To let this work you need a touch panel which works in low energy mode and probably an additional IC.

The problem with non OEM parts is that you actual never know how "original" they are.
If you order a part and it is not very clearly stated it is an original OEM part than it is a "copy".
So words as "original", "after market", "compatible with" are indicators that it is not an original OEM part.
Furthermore the price difference between an original OEM part and a "original", "after market", "compatible" make it tempting to buy a "copy" .

I hope above answers your question.



In

[rjacs]

Wow, thanks for the additional information. From what you wrote my guess is that the issue is the low energy state of the phone. If the new glass is less sensitive than the original than it won't work. I just did a new search for replacement glass for Lumia 520 including the term OEM. The products that came up differ from the 'original' that I bought in 2 ways; there is no branding, that is no Nokia at the top and more importantly you can see a tape border on the back of the screen. The original has the tape, my replacement does not. I don't know if this is related to the problem but without the tape the screen is closer to the digitizer and proximity screen.

[Harrie-S]

Before you buy it also check some reviews about the seller.

I am not sure where you from but in the past I bought from this company.
Nokia Lumia 520 Replacement Touch Screen Digitizer Glass Panel - Original
You do not need to buy here but the information about the part is at least very clear.