Built-in capacitive screen test

Question

Iron

Good day!
I would like to understand this:
I bought a Samsung phone with a capacitive touch screen today. Conducted a standard test * # 0 # * to check the sensor (this is where you need to sketch the screen with a green stripe).


So this is the question: I paint over the screen completely, to which the seller (a woman in years) rounded her eyes and the phrase was given to me: “You, here you only need to connect on the sides, you see the Samsung engineers are dumber than you.” I, prone to introspection, did not answer anything, and later I wondered if she was right and to check the screen you just need to drive it around.

I will leave here a link to the wiki on the device of touch screens

Answer 1

A very self-confident seller is rude to the buyer, it looks like he needs to change his job.
The seller does not understand the fundamental differences between a resistive and capacitive screen.
For a resistive screen, the seller answered almost correctly, and then only if the phone is brand new.
Capacitive screens have a different design and way of detecting clicks. Moreover, the touch point of pressing is calculated by a special chip, which, in theory, should even have an algorithm that would distinguish garbage from a human finger.
Touches are read through hundreds of thousands of sensors across the entire screen, and are not calculated based on the coordinates of touches on the X, Y scale. Therefore, the blind area of ​​​​the sensors due to a broken track or marriage can be anywhere and the connected frame will not show anything.