I'm currently replacing my screen for my Iphone and having issues with my touch screen dropping. The guy who sold it to me said he used this to test it.


With this being proof the screen worked

Now, I'd like to believe this guy but I'm curious as to how this box could test the touch screen, what could those little boxes mean?


  • \$\begingroup\$ I am almost sure stack exchange discourages opinion seeking questions. That said, the LCD and the touch screen are 2 different technologies. How well they are stuck together dictates how easy it is to replace one and not the other. So "replacing the screen" & talking only about the capacitive touch sensor is confusing. \$\endgroup\$
    – st2000
    Commented Jun 15, 2016 at 12:58
  • \$\begingroup\$ Isn't every answer on here someone's opinion (that they think is correct)? I'm asking for a facts, as in, how would this test the screen and what does that picture with the boxes mean. \$\endgroup\$
    – hybridchem
    Commented Jun 15, 2016 at 13:10
  • \$\begingroup\$ The "screen" comes with both the touch sensor and Lcd in one unit. I'm having issues with my touch part not working on the screen. \$\endgroup\$
    – hybridchem
    Commented Jun 15, 2016 at 13:12
  • \$\begingroup\$ The end of youtube.com/watch?v=6eJmBmYx1hk seems to show this in use. The operator does touch the screen minimally at one point. It may be that the numbers are readings from the sensing technology itself and would detect broken traces. Likely the point of the box is to save labor of assembling and booting a phone; if you want to do a full functional test you can probably find an app that displays pointer location - for comparison over in the Android world this is one of the code samples for the SDK, and I'm sure someone has though of it for iphone too. \$\endgroup\$ Commented Jun 15, 2016 at 13:30

1 Answer 1


You are asking if this is a legitimate test. It probably tests many feature. But with out touching the capacitive sensitive surface of the display with a finger, stylus or similar device, I don't see it actually validating all the expected functions of the UUT (Unit Under Test).

As for touch screens, there are many types. I believe you are interested in capacitive touch screens which fault under a variety of circumstances such as wearing gloves, high humidity (due point) and low humidity (static electricity) to name a few.

added later...

what could those little boxes with the numbers in them refer to

Guessing, since they are all about the same value & their distribution resembles the expected density of the actual touch screen sensors, they appear to be the raw values reported by each sensor. If true, this type of test would point out problematic sensors which might be masked by the layers of abstraction software used to improve the user's touch screen experience.

  • \$\begingroup\$ I didn't word my question properly but thanks for the insight. I was under the impression that it wouldn't validate it 100% without a function test. I should of clarified that my question was, what could those little boxes with the numbers in them refer to? \$\endgroup\$
    – hybridchem
    Commented Jun 15, 2016 at 13:16

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