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Metal core PCB:What is the touch principle of the smartphone screen

Article source:Editor:Sun&Lynn Mobile phone view
Popularity:1528Dated :08-30-2019 04:54【big well Small

  When we use the mobile phone at ordinary times, if there is something between the hand and the mobile phone screen, the mobile phone will not react when operating the mobile phone screen. So, why do you need to touch your skin to slide the screen when using your mobile phone? This requires us to understand the screen of the mobile phone.

  The touch-screen mobile phone we used to use will be equipped with a stylus for you. When we use the mobile phone, we directly use the stylus to operate, or use the fingernail to slide, rather than using the skin of the finger. This is mainly because the touch-screen mobile phone used the resistance screen at that time. . Resistive screen is a liquid crystal display that can sense, actually it is a very thin screen with conductive layer. So when the screen is pressed by us, the sensing device in the screen can receive the touch signal. Therefore, due to the working principle, the resistance screen can work even without skin contact.

  However, Metal core PCB think,the mobile phones we are using now all use capacitive screens. The working principle of this screen is to use the current induction of our human body to trigger the screen reaction to work.

  Capacitive screen is composed of a multi-layer glass, usually four layers. When making this screen, a layer of indium tin oxide, called ITO, is added to the surface of these layers of glass. The interlayer ITO coating is the place where the work is done. The four corners of the capacitive screen are used to lead out four electrodes. In the outermost layer of the glass is a protective layer made of silica glass, this layer of glass is very thin, only 0.0015 mm.

  As we all know, our human body is equipped with a magnetic field, which is composed of magnetic substances and electric current, that is to say, our human body is charged and can conduct electricity. When our finger skin touches the screen, the capacitive screen of the mobile phone will use the electric field of the human body to form a coupling capacitor between the screen and the human body, so that the two electric fields are coupled through the capacitor, thus connecting a high-frequency signal channel. This high-frequency current uses a capacitor as a direct conductor. When we touch the capacitive screen, the finger skin will suck a small current on the screen, and the control device on the mobile phone will sense the position of this current on the screen and react quickly to achieve the purpose of touch screen.

  However, capacitive screen can not only react through skin contact, but can work if coupling reaction can be satisfied. Therefore, many manufacturers have invented tools that can slide the capacitive screen, but basically no one will use them.

  Also because of this, if our fingers have water, it will lead to large areas of current phenomenon on the capacitive screen, the control device cannot accurately sense the contact point of the fingers, and there is no difference between clear water and fingers in the sensing of the control device, because both can form current. At this time, the touch will drift and the screen will be insensitive when sliding.

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