Why The Touch Screen Of Mobile Phone Needs Skin Contact To Slide

Why The Touch Screen Of Mobile Phone Needs Skin Contact To Slide

Nov 12, 2019

If you wear gloves or have water on your fingers, the phone will not respond when you touch the screen. So, why do mobile screens need skin contact to slide? First of all, we need to understand the screen problems of mobile phones. Now the screen of the mobile phone we use is a capacitive touch screen, this screen is the use of the human body's current induction to work. And we can only slide the phone when the skin contacts, which is also related to the working principle of the capacitive screen.

The capacitive touch screen is a four layer composite glass. Between the four layers of glass and the inner surface, there is a layer of indium tin oxide (n-type oxide semiconductor), referred to as ITO, while the interlayer ITO coating is the working surface, and the four corners of the screen are used to lead out four electrodes. In the outer layer of the glass, there is a layer of silica glass as a protective layer, which is very thin, only 0.0015 mm.

We know that the human body has a magnetic field. The biological magnetic field of human body is produced by bioelectricity, biomagnetism and some exogenous magnetic materials. That is to say, there is electricity in our body and it can conduct electricity. When we touch the screen, the capacitive touch screen of mobile phone uses the electric field of human body to form a coupling capacitance between the screen and the user, which makes the strong current and the weak current couple through the capacitor to provide a high-frequency signal path. For this kind of high-frequency current, the capacitance is the direct conductor. When we touch the screen, the skin of the finger will absorb a small current. The controller on the mobile phone will calculate the position of the current and react to meet our operation needs.

Second, we need to know why some mobile phones can be operated without skin contact. Previously used functional mobile phones with touch screen function will be equipped with a touch pen. When we play with mobile phones, we need to pull the stylus out of the phone, and then operate it again, without using fingers. This is because the screen of this kind of mobile phone uses resistance screen. The working principle of the touch screen of resistance technology is different from that of the capacitance screen.

The resistive touch screen consists of an inductive liquid crystal display device, the main part of which is a resistive film screen with a conductive layer on the surface. When we press the screen with something, the sensor will receive the touch signal. Therefore, because of the difference of working principle, the resistance screen can work even without skin contact.

In addition, it should be noted that the capacitive touch screen does not have to be in contact with the skin to react, only needs to meet the coupling reaction, and the capacitive touch screen can work. So now many businesses have invented a tool that can slide the screen, which greatly facilitates the use of users.