“Wireless” has always been one of the unremitting pursuit of mobile phones, because the mobile phone itself was born to “abandon” the phone line. Although the mobile phone abandoned the phone line/network cable through wireless communication technology, and later “abandoned” the wired headset through the upgrade of Bluetooth technology, now the only cable that the smart phone must use is the charging cable.
Abandoned headphone jack and charging cable
The charging cable can be said to be a hardcore accessory for mobile phones. Since the era of feature phones, the charging cable has been an essential accessory for mobile phones. From the initial integrated design of the charging cable and power adapter to the current split design, the charging cable has always been the main way for mobile phones to replenish the power. However, as the wireless charging technology matures, the charging cable may no longer be a “necessity.” “Again.
Wireless charging technology
Wireless charging technology seemed to be “black technology” a few years ago, but now wireless charging technology has been widely used in various electronic products, let me introduce wireless charging technology specifically for you. The technical principle of wireless charging
In fact, wireless charging technology has appeared very early, and the commercial use of mobile phones mainly began in the era of smart phones. The Nokia Lumia series is an earlier smartphone that adopted wireless charging technology. Its representative model, the Nokia Lumia 920, was launched in 2012.
However, in the context of the prevailing metal body design at the time, there was no wave of popularization of wireless charging. In 2017, the iPhone 8 series models with a glass body design and wireless charging technology came out, and wireless charging has only begun to spread widely.
iPhone8 wireless charging
The current wireless charging scheme is mainly based on inductive technology with relatively simple technology and high maturity; this technology is based on Faraday’s law of electromagnetic induction, and the electromotive force is generated by cutting a magnetic field through a conductor, which is generally composed of two coils, on the primary coil A magnetic field is generated when AC power is connected, and the secondary coil induces an alternating current due to the existence of an alternating magnetic field; the disadvantages of inductive wireless technology are low charging power, short charging distance, and high positioning accuracy requirements.
Wireless charger coil
To a certain extent, the principle of inductive wireless charging has become a factor in the slow popularity of wireless charging. First of all, the principle of electromagnetic induction determines that the material of the back cover of the mobile phone cannot be a metal shell, because the metal shell will be heated during wireless charging and cause danger; Secondly, a coil needs to be added to the mobile phone, which is more difficult for the increasingly scarce mobile phone body space; the charging power of the previous wireless charging is not high compared with the fast-developing wired fast charging.
Mobile phone wireless charging coil
In addition to inductive wireless charging, there is also a resonant wireless charging technology. In 2012, Apple applied for a wireless charging patent related to resonance wireless charging technology. It is reported that this patented technology can establish a charging area with an effective range of 1 meter through the “near-field magnetic resonance” technology. As long as the device supporting this technology is placed in the charging area, it can carry out contactless long-distance wireless charging. The technology has not yet been commercialized.
Universal Qi standard
There are currently three well-known open protocol standards for wireless charging technology, namely PMA, Qi, and A4WP. The Qi standard is the wireless charging standard that is most widely used in smartphones and has practical value.
The Qi standard was formulated by the WPC Wireless Charging Alliance, which was established in 2008. It is an open and cooperative standard-setting organization composed of more than 600 company members. It aims to create and promote widespread market adoption and all rechargeable The international wireless charging standard Qi compatible with electronic devices. The logo of the Wireless Charging Alliance is “Qi”-“Qi” means “qi”, and in Asian philosophy represents “vital energy”-an invisible energy.
The Qi standard is a global standard with wide applicability and compatibility. Any charger with the Qi logo can wirelessly charge any rechargeable device that meets the Qi standard. Qi provides a simple, convenient and flexible Mechanism to ensure compatibility and interoperability between charging devices and mobile devices of different brands and manufacturers.
Wireless recoil based on Qi standard
Therefore, the Qi standard is currently the most common wireless charging standard. In addition to the Qi standard, the PMA and A4WP standards are also well-known. However, these two standards are currently not common on mobile phones, so we will not introduce them.
The future of wireless charging
I think there are two main directions for the development of wireless charging technology in the future. One is more extensive IoT applications, and the other is to replace wired chargers with faster charging power.
In terms of IoT applications, the contactless nature of wireless charging allows IoT devices to bid farewell to traditional contact charging methods. For example, many sweeping robots now need to physically contact the contacts of the charging pile to be able to charge, while wireless charging technology The robot can be docked in the charging area to complete the charging; and devices such as electric toothbrushes can also use wireless charging technology to cancel the charging interface on the fuselage, so as to obtain better waterproof performance.
Wireless charging electric toothbrush
Faster charging power is naturally aimed at devices with larger battery capacity such as mobile phones and tablets. With the advancement of wireless fast charging technology by mobile phone manufacturers, the current wireless charging speed of mobile phones does not lag behind wired charging, which makes it more possible for wireless charging to replace wired charging.
Because, we are likely to see that just like wired earphones are quickly replaced by wireless earphones, in the next few years, various charging cables will also be replaced by wireless charging technology, and wireless charging technology will also be the Internet of Things. The development offers more possibilities.