Author Topic: random phantom touches - how to fix?  (Read 835 times)

soundwater

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random phantom touches - how to fix?
« on: October 22, 2018, 11:36:59 PM »
Hello,

We are using the FT5x06 and are experiencing a flurry (maybe 20 to 50) of random touches when I press a specific part of the touch screen (upper left corner). The flurry only happens for maybe 1 second. then all is well. Also, after the initial touch in the upper left corner, the phantom touches happen after a short delay - maybe 1 or 2 seconds.

I have no idea what causes this or where to start looking for a solution. It is repeatable, and seems to get worse over time, i.e., the more I use the display the phantom touches come in larger flurry. I did scope out the data lines on the touch screen, and it looks like there is indeed some data coming down the line after the initial touch in the upper left corner of the screen. It is somehow also related to what is on the LCD when I press the upper left corner. We are running an Android App, and seems to only happen when the sidebar of our app is showing. If it is not showing and I press this location, then it doesn't happen. very very strange.

Can someone out there with experience in random phantom touches point in the right direction?

Thanks in advance!

Sergio_M

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Re: random phantom touches - how to fix?
« Reply #1 on: February 08, 2019, 09:36:25 AM »
Hello,

Could you please confirm the display's part number.

A good place to start would be to find out if any components in your design are generating noise that the touch panel might pick up. The display's bezel can act as a shield keeping noise from other system components from reaching the touch panel, it is good practice to ground the display's bezel.
A few tips that should help improve your design and eliminate ghost touches:

- Ground the display's bezel.
- Use flat cable ferrite core, used for the FPC / FCC cable.
- Use EMI shielding foils and films.

Best Regards,

 

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