What are the reasons for the failure of capacitive touch screen?

- Jun 25, 2019-

What are the reasons for the failure of capacitive touch screen?


Let us first look at the working principle of the capacitive touch screen: the capacitive touch screen is a four-layer composite glass screen. The inner surface and the interlayer of the glass screen are coated with a layer of ITO (transparent conductive film), and the outermost layer is a thin layer of alumina. The glass protective layer, the interlayer ITO coating is used as the working surface, four electrodes are led out at the four corners, and the inner layer of ITO is the shielding layer to ensure a good working environment. When the finger touches the metal layer, the user and the surface of the touch screen form a coupling capacitor due to the electric field of the human body. For high-frequency current, the capacitor is a direct conductor, and the finger sucks a small current from the contact point. This current is discharged from the electrodes on the four corners of the touch screen, and the current flowing through the four electrodes is proportional to the distance from the finger to the four corners. The controller calculates the position of the touch point by accurately calculating the ratio of the four currents. .

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Here are a few common reasons why touch failures are caused:

1, static electricity

Since the capacitive screen is positioned by the electric field, very slight static electricity can cause "drift". If an electrostatic discharge occurs, the capacitive screen may even be permanently damaged.


2. Magnetic field

The magnetic field generates an electric field, so the "drift" phenomenon occurs when the capacitive screen is in a strong magnetic field. If the magnetic field is too strong or is in a strong magnetic field for a long time, it may even damage the capacitive screen permanently. So if you find that the phone screen suddenly fails, you can see if there is something with strong magnetism around.


3, conductive materials

Conductive substances attached to the screen, such as oil, sweat, moisture, etc., can cause "drift" phenomenon, and if accidentally flow into the inside of the screen, it may even permanently damage the capacitive screen and other components. This is actually the most cause of the failure of the capacitive screen, but now many high-end capacitive screens use ultra-sensitive touch technology, which can solve this problem very well, I believe that the future capacitive screen mobile phone will use this technology.


4, ambient temperature and humidity

The optimal operating temperature of the capacitive screen is 5 ° C ~ 35 ° C, the working humidity is 30% ~ 90% without condensation, there may be "drift" phenomenon when the working environment is not satisfied. The storage temperature of the capacitive screen is -20 ° C ~ 60 ° C. Storage and transportation in high temperature or low temperature environment may damage the capacitive screen. Special attention is paid to the fact that the capacitive screen is more afraid of high temperature. If it is exposed to sunlight for a long time or placed in a high temperature environment for a long time, it may permanently damage the capacitive screen. After charging causes the screen to heat up, please wait for the screen temperature to drop before using it.


5, voltage

When the battery voltage is low or the voltage is unstable, the capacitive screen may “drift”. Using a good battery and charging your phone in time can avoid drift caused by voltage problems.


6, physical damage

Impact and vibration can damage the bauxite glass protective layer and/or ITO, causing permanent damage to the capacitive screen, causing "drift" and even causing the capacitive screen to be completely scrapped. Therefore, when storing and transporting, it is necessary to avoid large vibration and collision as much as possible; in the use, it is necessary to eliminate the strong tapping, thereby protecting the capacitive screen and prolonging the service life.


7. The touch control module is damaged or its cable is loose.

The screen of the current touch screen mobile phone is physically divided into two parts, one is responsible for the screen display of the LCD screen, and the other is the touch control module responsible for feedback touch information. There may be two kinds of faults. One is that the touch module itself has a hardware problem and needs to be replaced. The other possibility is that the connection cable between the touch module and the LCD screen of your mobile phone is loose. If the cable is loose, it can be solved by reinserting it after disassembling the machine.


8, system problems

If there are many mobile phone system installation applications, and the mobile phone configuration is not high, it is easy to cause insufficient mobile phone resources. Therefore, such a phenomenon may occur. It is recommended that you try to restore the factory settings or try the machine after brushing, but it is not OK, and it is better to take over the repair. .


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