Capacitive screen principle - the mystery of mobile touch screen work ~

Mobile phone crystal 3.2*2.5mm 3225 26M (26.000MHZ) 7.5PF 10PPM 20PPM 30PPM

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AVX tantalum capacitor low resistance TPSD107K016R0100 original 2011+

Tantalum capacitor

Guide: The capacitive screen is actually a glass screen located on the surface of the mobile phone. It is used to receive the information sent by our fingers and transmit it to the inside of the mobile phone for corresponding processing. It can be said that without the capacitive screen , there is no "head" Broken, blood can flow, the mobile phone can not be lost "the smart phone, then how does the capacitive screen work for us? Let's take a look at the small series below~

First, the principle of capacitive screen - - Introduction

Capacitive screen, the full name of capacitive touch screen, the English name is capacitive touch screen, commonly known as hard screen, in short, it is a kind of sensor, when we use a finger to touch, it can form a loop to generate current to sense the position we touch. Complete some of the preset features. In addition to the capacitive screen, there is also a resistive touch screen on the market. This type of touch screen uses external force to generate deformation to sense external touch, and the accuracy is low, and the application in the market is gradually reduced.

Second, the principle of capacitive screen - - structure

Capacitive screen, the surface is only a layer of glass, in fact it is composed of four layers of material, the base layer is a layer of simple glass, inside and outside the glass are coated with nano-indium tin oxide (ITO), at the outermost layer (the layer that our fingers touched), is a bauxite glass protective layer. Among them, the second layer of ITO is used as the working surface, and electrodes are drawn at the four corners thereof, and the fourth layer of ITO is used as the shielding surface for isolating the internal structure of the capacitive screen and other mobile phones.

Third, the principle of capacitive screen

The capacitive touch screen works based on the conductivity of the human body. When the finger comes into contact with the capacitive screen, the finger and the capacitive screen form a small coupling capacitance. According to the capacitance, “AC, DC, DC; high frequency, low frequency The characteristic can be concluded that the high-frequency signal flows out through the capacitor, and then the information is transmitted to the mobile phone through the four electrodes of the capacitive screen to obtain the position of the touched point.

Fourth, the principle of capacitive screen - - the difference between the resistance screen

Since the resistive screen is deformed by pressure to sense the touch of the external touch of the mobile phone, it requires a relatively large force to press, the sensitivity is not high, and the long-term strong pressing makes the touch screen extremely vulnerable; and the capacitive screen is based on the human body current. The principle is as long as the finger touches the screen, the accuracy is high, and it can be used for a long time.

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