Contemporary mobile phones are all touch screens. Why can a touch screen respond to human touch?

There are two kinds of touch screens used in contemporary mobile phones, one is resistive touch screen and the other is capacitive touch screen.

The early mobile phone touch screen is a resistive touch screen, which exerts pressure on the screen through fingers or stylus to produce a touch effect and trigger behavior instructions. However, with the gradual development of the mobile phone industry, this kind of touch screen has been gradually eliminated.

Now we use a capacitive touch screen, which is actually composed of two layers of mobile phone screens, one is a traditional glass screen, and the other is transparent metal, which is quite special, probably because of its transparent characteristics. In fact, the touch screen is completed by the contact between fingers and this transparent metal.

When we use a touch-screen mobile phone, when our fingers touch this layer of conductive metal, the capacitance of the touched position on the screen of the mobile phone will change. Then the frequency of the oscillator connected to it changes. The effect of touch screen is realized by this changing frequency.

Because the capacitance will be affected in many ways, there will be errors in the use process. For example, when there is water on the screen, it often affects the normal use of the touch screen. When we use it, sometimes we accidentally drop water on the screen of the mobile phone. If you don't erase it in time, you will find that the screen with high sensitivity can't slide down.

Compared with resistive touch screen, capacitive touch screen is more advanced. For example, resistive touch screen can only support single touch, while capacitive touch screen can realize multi-touch. Just like when we play games, it is often controlled by two hands. In this case, a resistive touch screen cannot be realized.