The touch screen senses the touch of our fingers because when the fingers touch a specific position on the screen, it is equivalent to sending an accurate electronic signal to the screen. There are many types of touch screen, which can be roughly divided into resistive touch screen and capacitive touch screen. At present, the most widely used is “capacitive touch screen”.

The first layer of our mobile phone is the protective layer, and the lower layer is the touch sensor layer. The touch sensor layer is coated with a thin conductive metal material, such as indium tin oxide. This touch sensor layer is actually composed of two layers. Each layer has tiny electrodes at regular intervals. The two layers overlap each other and can arrange a checkerboard like grid full of screen. Of course, the spaces in it are much denser than the checkerboard.

How does the touch screen work

We can’t see them from outside the screen because they are basically transparent and full of the whole screen. Each grid on these “checkerboards” is an electrode. They all have different “charge” numbers. Without touching the screen, they are in equilibrium. Once your finger touches the screen, because the finger is a conductor, it will bring “interference” to the electrode under the screen, that is, it will bring new charges, which will destroy the original equilibrium state.

How does the touch screen work

Here we take the capacitive touch screen as an example, so the result of the destruction of this balance state is that your finger changes the “capacitance” of the point touching the screen. The change of capacitance will be sensed by the chip inside the mobile phone. Chips and sensors will calculate a series of changes such as electric field and current, and then calculate the position of the point where your finger contacts the screen.

So the premise of all this is that your finger is a conductor, not a glove. It is an insulator, so there is no response when touching the screen.

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