Touchscreen (display) failures - what's the root cause?

Hello there!

There have been several reports by users on this forum over the years of touchscreens exhibiting problems - mostly areas that no longer respond to touches, and of ghost touches.
I’ve been affected since a few months as well.
Given that I’ve got one of the first 17 418, with the original screen, I’m happy that it worked as long as it did. Especially considering how much I drop my phone :roll_eyes:

But the point of this thread is that I want to figure out what exactly is broken inside the screen.
In my case, the right border has a strip that no longer responds to touch. It seems to me that the width of this strip has increased at least once. Since about two weeks or so, I have also been getting ghost touches - the touchscreen reports touches all along the border between the responsive and unresponsive parts. When it happens, it happens in prolonged bursts of rapid touches. If you have the same problem, you can turn on touch visualization in the developer options to see where they are.
In between those bursts, touch input works normally in the responsive part. The bursts have increased in frequency in the last days, and I fear the screen will soon be unusable.

However, it seems to me that tapping the phone rather harshly, pressing on the screen or the back without the cover or very slightly twisting the screen can stop a burst of ghost touches.

That intrigues me: What’s going on? Have some of the tiny traces inside the screen broken or shorted? Or is it maybe something in the connector between screen and core module? Is it the contact pins?

I’m looking for any insights or ideas from you :slight_smile:

To the Fairphone team: Can you share anything about this failure? Do you know what the cause is, and are you at liberty to say?

Cheers!

Touchscreen issue have many origins. This week someone that contacted my heaven had her issue solved by a factory reset. Yours appears to be hardware issues.

If you know another FP2 user or if you are near a FP angels’ heaven you should try swapping the screen modules. If this solves the issue then your module is probably the problem and you can buy a replacement.

Still the touchscreen working partially suggests a problem with the connectors. You should try to clean them. Read here:

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Hi Agno,

thanks for your reply! Yes, I’m certain that my screen has hardware issues. I’ve tried contact cleaning (more than once, in fact). and while it seems better right now, I don’t have high hopes.

Anyway, while I’d be happy about a fix, what really interests me here is what exactly it is that doesn’t work.
For example: if it is any way related to the connector, I’m just really curious to know how exactly. The connector has about 20-30 pins. How are these used exactly? How is the data transfered back and forth? Could it really be that one pin is responsible for a certain area of the screen? I think that’s very unlikely, but I want to know how the interface works anyway.

Same goes for the internal layout of the screen, and possible failure modes. I’m really looking for technical details. The more you can throw at me, the better :smiley:

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