Capacitive screen is causing trouble? Why does the screen float when the phone is charging?

Although playing with your phone while charging is not recommended, accidents are inevitable. If you are chatting with your girlfriend and suddenly your phone runs out of power, wouldn't you be sad? At this time, after connecting to the power supply, something even more sad happens. The screen drifts, the dots are inaccurate, and finally it simply fails. In fact, screen failure during charging often occurs. For most people, screen failure is indeed a very annoying thing. So, what is the reason for screen failure? We don't need to delve into the difficult electrical knowledge, so I will simply explain the reason.

In fact, all this is mainly caused by the capacitive screen of the mobile phone. As we know, the capacitive 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 (conductive glass). The outermost layer is a thin layer of silica glass protection layer. The interlayer ITO coating is used as the working surface. Four electrodes are drawn out at the four corners. The inner layer ITO is a shielding layer to ensure a good working environment. When the finger touches the metal layer, due to the conductor properties of the human body, a coupling capacitor will be formed between the user and the touch screen surface.

Capacitors are direct conductors. The user's finger can absorb a very small current from the contact point, and then this current flows out from the electrodes on the four corners of the touch screen. The current flowing through these four electrodes is proportional to the distance from the finger to the four corners. The controller obtains the position of the touch point by accurately calculating the ratio of these four currents.

You should know that most of the mobile phone screens nowadays are capacitive screens. Since the capacitive screen is controlled by capacitive induction, it means that the capacitive screen has very high requirements for the stability of the power supply. The AC waveform is a sine curve, while the battery power supply is direct current, which has higher stability. When charging directly, using a general low-quality charger will cause the screen to malfunction. That is because the stability of the low-quality charger is extremely poor, the capacitor used is too low-quality or has no inductance components, and there are very serious ripples when detected with an oscilloscope. Some chargers have capacitors that age over time, which causes the pulse waveform of the pulse transformer to be unable to be removed cleanly, resulting in residual waveforms. Working under this ripple will interfere with the screen, and even the surface of the screen will be covered with static electricity, so that the screen cannot correctly identify the exact location of human skin contact, and thus cannot work properly. This is the reason for the screen failure.

Well, after finding the cause, there is naturally a solution. First of all, try to use brand-original chargers and data cables. Compared with non-original chargers, original authentic ones can provide more stable current. If you don't have an original charger, the editor recommends that you can choose to charge with a computer.

For professional users, you can also solve the problem of screen failure by using filter capacitors. The so-called filter capacitor is an energy storage device installed at both ends of the rectifier circuit to reduce the AC ripple coefficient and improve the efficient and smooth DC output. Its function is to filter out the AC component and make the output DC ripple smoother.

Secondly, upgrading the software system and flashing a stable and efficient ROM can also avoid the situation of mobile phone screen failure to a certain extent. Of course, the combination of software and hardware is not tiring. While upgrading the software, it is also very important to upgrade the hardware. If the screen is already aged, it is more comfortable to directly replace the phone/screen. For most people, screen failure is indeed annoying. However, as long as you can follow the instructions to use the phone, you can avoid problems with the phone to a large extent. Finally, the editor solemnly reminds that it is still risky to play with the phone while charging, so try not to try it.

As a winner of Toutiao's Qingyun Plan and Baijiahao's Bai+ Plan, the 2019 Baidu Digital Author of the Year, the Baijiahao's Most Popular Author in the Technology Field, the 2019 Sogou Technology and Culture Author, and the 2021 Baijiahao Quarterly Influential Creator, he has won many awards, including the 2013 Sohu Best Industry Media Person, the 2015 China New Media Entrepreneurship Competition Beijing Third Place, the 2015 Guangmang Experience Award, the 2015 China New Media Entrepreneurship Competition Finals Third Place, and the 2018 Baidu Dynamic Annual Powerful Celebrity.