Science summary: Why does the phone screen get wet?

An easy answer: Why does the phone screen fail after it gets wet?

Why does the current mobile phone fail when the phone is flooded? Many waterproof phones can't be operated in the water. What is the reason?

Before answering, Xiaobian needs to explain to everyone, in fact, the screen of the mobile phone is divided into a capacitive screen and a resistive screen. Most of the screen failures that occur after watering are mobile phones with capacitive screens. The capacitive screens use the current sensing of the human body. working.

The touch screen is coated with narrow electrodes on all four sides. When the user touches the screen, due to the human body electric field, the user and the touch screen surface will form a coupling capacitor. For high-frequency current, the capacitor is a direct conductor, so the finger will come from the contact point. A small current is drawn away. 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. .

Simply put, where the user touches, where is the "leakage", the screen responds. When the screen is wet by water, because of the conductive nature of the water, when the water touches the screen and the hand touches it, the current will be affected, so the above calculation is not accurate. This is also called screen drift.

Of course, not all capacitive screen phones are afraid of water. In general, capacitive screens are divided into two types, one is self-capacitance and the other is mutual capacitance. Relatively speaking, the self-capacitance algorithm is easy to handle this problem. (Simply speaking, it automatically ignores the capacitance brought by water), and the resistance will be stronger. However, the self-capacitance can only be virtual two points. The current mobile phones are at least 5 points of mutual capacitance. For mutual capacitance, the contact response generally does not include the reference of the signal strength value, and the problem of water droplets will be more obvious.

Nowadays, mobile phones that can operate with water are basically enhanced in signal processing accuracy and higher refresh rates, enabling them to resolve small signal changes. In this way, even if the water forms a conductive surface, when the hand point is down, a slight signal difference is formed in the conductive surface at the position of the finger to determine the touch position.

By the way, the resistive screen is different from the capacitive screen. The resistive screen has two conductive layers. There are many small transparent isolation points between the two layers to separate the two layers. When the finger presses the screen, the two conductive layers are touched. There is contact at the point location and the controller can detect and calculate the position. However, due to the poor control experience, the resistive screen has gradually faded out of the history of the mobile phone field.

A question and answer: How much faster than the phone will be charged when the phone is turned off?

In fact, on this issue, some people have raised doubts long ago. I remember that last year, a quick charging trick was circulated on the Internet, saying that the phone can be turned off or switched in flight mode charging, and the speed can be doubled. Undoubtedly, when the mobile phone is turned off, the charging speed is inevitably faster than that in the power-on state. Some people have tested it before.

The Daren prepares a mobile phone with a battery capacity of 1000-1600MAh, which tests the standby state of the mobile phone, the flight mode, and the charging time in the off state.

At 7:35 pm on the first day, when the mobile phone is about to run out, the person starts charging and keeps the phone in standby mode, stopping the Internet, making a phone call, etc. during charging. At 10:48, the phone emits a "beep" power full of sounds. The results show that the standby state takes 193 minutes to charge.

At 9:01 the next night, the phone's power is exhausted again and automatically shuts down. The reporter started the charging experiment in the off state. This time the speed is slightly faster. At 23:49, the screen shows that the power is 100%, and it takes 168 minutes before and after.

At 11:15 on the third day, the person completely exhausted the mobile phone battery and began to use the flight mode to charge. At 2:10 pm, the mobile phone is fully charged. This charging takes 175 minutes.

The results of 3 experiments show that the shutdown charge saves 25 minutes faster than the standby state, and the speed is about 13% faster; the flight mode charge saves 15 minutes faster than the standby state, and the speed is about 9% faster.

Of course, mobile phones with different capacities will have some discrepancies in full charge, but one thing is certain is that the shutdown charging and flight mode charging must be faster than the normal standby charging.

If you have to pursue the reason, you can understand that the signal is off in the flight mode, and some software in the background can't access the network, so the power consumption is small. However, I believe that for most of my friends, I will not choose to turn off the mobile phone signal because of that time. After all, the communication interruption will bring a lot of inconvenience. I want to charge quickly and it is just for better use of the mobile phone. Then, paying attention to some small details can still reduce the power consumption of the mobile phone and extend the standby time of the mobile phone.

For example, adjust the over-bright screen and turn off the screen in time to shorten the screen timeout. At the same time, you can turn off applications and background programs that are not used temporarily. After sleeping at night, turn off services such as WiFi and GPS to ensure the battery life.

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