In recent years, smartphone-related technologies have become increasingly mature, and the technological achievements they bring are constantly attracting attention. Just recently, the Nokia Lumia 920, which has become famous recently, first used a technology called "wireless charging", which has widely aroused people's curiosity and attention. People think that it is a very magical function and technology. In fact, after I searched for relevant information, I found that wireless charging technology actually appeared a long time ago, but after development in recent years, it has now become mature and easy to use, and has been used in some home appliances such as electric toothbrushes and electric shavers. Expanded to the field of smartphones.

The so-called wireless charging technology, as the name suggests, transmits energy to electronic devices through the air to achieve the purpose of charging. Wireless charging technology is mainly implemented through three methods: electromagnetic induction charging, magnetic field resonance charging and radio wave charging. The wireless charging of Nokia Lumia 920 uses electromagnetic induction charging.

First, we will introduce electromagnetic induction charging. The principle we have learned in high school is that when current flows through a coil, a magnetic field will be generated around it. This is the electromagnetic effect discovered by Danish physicist Oersted; and when other coils that are not energized are close to the magnetic field, the magnetic field in the coil will An electric current will be generated. This is the electromagnetic induction phenomenon discovered by the British physicist Faraday. Electromagnetic induction wireless charging technology combines these two ideas and uses the principle of electromagnetic induction for charging: there is a coil at the sending end and the receiving end. The sending end coil is connected to the wired power supply and generates electromagnetic signals through electromagnetic phenomena. The receiving end coil senses the electromagnetic signal generated by the transmitting end and generates electricity through electromagnetic induction to generate current to charge the battery. Of course, there needs to be a certain distance between the transmitter and the receiver to demonstrate the convenience of wireless charging. This power transmission distance is about a few millimeters to ten centimeters, which is relatively short, but this distance is not suitable for smartphones commonly used. It's enough, we only need to place the battery and receiving device on the charging platform to charge it, eliminating the trouble of wiring. Its principle and production are relatively simple, so there are many posts on the Internet about modifying mobile phones into wireless charging mobile phones. The general method is to connect a coil fixed on the back cover to the battery interface of the mobile phone, and then connect the mobile phone to the battery interface. Place it on the wireless charging platform for charging.

There is also magnetic field resonance charging. Its basic principle is the principle of magnetic field coupling resonance, which is similar to the resonance of sound. It is not difficult to imagine that if tuning forks with the same vibration frequency are arranged, one will sound and the other will resonate and sound; similarly, when there is current in one of the two coils adjusted to the same frequency in the magnetic field, the other will It will create an exchange of energy with it, thereby producing an electric current. The working principle of the wireless charger according to his invention is that there is a transmitting end and a receiving end. The transmitting end is supplied with direct current and converted into a high-frequency AC signal through a resonant converter, so that the transmitting end coil generates a signal within a certain distance around it. An electromagnetic field with large changes in high frequency. When the receiving end coil is located in this electromagnetic field, the high frequency changes in the magnetic flux of the transmitting end coil will generate a certain high frequency induced electromotive force in the receiving end coil, and then pass through the device added to the receiving end coil. , the receiving end can generate DC current to charge the battery. Magnetic field resonance charging is different from electromagnetic induction charging. It does not emit electromagnetic waves, but only forms a magnetic field around it. It consumes less power than inductive charging and has a longer transmission distance, ranging from tens of centimeters to several meters. This technology has been used in transportation vehicles such as automobiles and maglev trains, but it is only in the experimental stage.

Finally, there is radio wave charging. Its basic principle is similar to that of early mineral radios. According to the principles of physics, changes in the intensity of the current in the transmitting end conductor will generate radio waves, and radio waves can carry and transmit energy. At the same time, when radio waves are transmitted to the receiving end through space, the changes in the electromagnetic field caused by the radio waves will produce a resonance effect, which will generate current in the conductor at the receiving end, thus realizing wireless charging using radio waves. There are already technology products that can use this principle to capture and convert the radio waves emitted by the transmitter on the socket, including those bounced off objects, into direct current to charge low-voltage electronic products within an effective range of one meter.

Wireless charging technology currently has some shortcomings, such as large energy loss, inability to support high-power charging, inability to support long distances, large electromagnetic radiation, and safety hazards. But none of these can stop it from showing its charm. Just imagine, if in the future our mobile phones, computers, etc. no longer need to be bound by wires, if we no longer have to carry a lot of data cables with us when traveling far away, if electric vehicles and other transportation Tools can be charged while walking. That kind of life will be infinitely convenient and beautiful. I believe that in the near future, scientists will be able to solve these technical difficulties, use physics to change life, and use technology to make life better!