Structure and merit demerit of Vol.05 wireless Charge Qi
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Merit demerit of wireless Charge Qi

Structure and merit demerit of wireless Charge Qi

"Qi" (tea) is convenient standard that can charge wireless without adding cable in smartphone. "Tea" comes from reading of "mind" to mean "invisible power" in Chinese.
What kind of structure does Qi which is this groundbreaking standard move in? We explain merit demerit after having introduced type or standard of Qi here.

Structure of wireless Charge Qi

Structure of wireless Charge Qi

Qi is International Standard of wireless Charge, and group called "WPC" (Wireless Power Consortium) performs standard development and promotion. At first, let's introduce representative type and principle, standard of wireless Charge.

Representative type of wireless Charge

Electricity does not fly about air average like thunder even if we say wireless Charge. Type of representative wireless Charge method includes "electromagnetic induction method" "magnetic field resonance method" "electric field-binding method" "electric wave receiving system".

Representative type of wireless Charge

・Electromagnetic induction method

It is method to let electromagnetic induction method produces instruction magnetic flux between side transmitting electricity and side letting you receive and charge. It is general method in wireless Charge because it can come true in small size and low cost.
However, we cannot charge properly when there is gap at position with side transmitting electricity and side to receive as transmission range is short.

・Magnetic field resonance method

Magnetic field lets you be resonant with resonator of side where magnetic field resonance method transmits electricity to and side to receive and is method to produce electricity, and to charge. Even if distance is far in comparison with electromagnetic induction method, we can charge. It is studied for the one for Charge of electric car now.

・Electric field-binding method

By electric field-binding method, we prepare electrode between side transmitting electricity and side to receive and form condenser (capacitor) by letting that meet. As phenomenon that electricity is passed to counterpart electrode gets up when we divert electricity of high frequency to this condenser, we charge using this.
It is the short transmission distance, but there is merit that is hard to be affected by position gap as well as electromagnetic induction method.

・Electric wave receiving system

We convert electric current into electromagnetic wave once in the neighborhood where we transmit electricity and receive with prepared antenna on side receiving the electromagnetic wave. It converts the electromagnetic wave which it received into direct current in rectifier circuit, and it is electric wave receiving system that charges using this. It is merit that has a long transmission range, but it is problem to have bad electric outbreak efficiency.

Principle to perform wireless Charge in Qi

Qi adopts electromagnetic induction method among structure of wireless Charge which mentioned above. This electromagnetic induction method is based on "denjiyudosoku of faraday" and uses principle "that magnetic field occurs when we bring magnets close, and electric current drifts" to if we easily say.

Specifically, smartphone incorporates "coil for receiving" in terminal of side to charge with "coil for the transmission" to wireless battery charger to send electricity to. Then, magnetic field (magnetic flux) is caused when we spend alternating voltage on coil for the transmission. Induced electromotive force to deny the magnetic field occurs when we bring coil for receiving close in state that this magnetic field produced.
Electromagnetic induction method is structure charging terminals such as smartphone using induced electromotive force occurring at this time.

Principle to perform wireless Charge in Qi

Standard of wireless Charge

There are multiple standards of wireless Charge, and group called "WPC" devises standard of Qi, and "electromagnetic induction method" of "non-emission type" is adopted. There are AirFuel Inductive (old PMA) standard that group of wireless Charge called "AirFuel Alliance" promotes other than Qi standard and AirFuel Resonant (old Rezence) standard. We do not know whether standard that which group promotes becomes standard, but are adopted a lot Qi standard in Charge of smartphone at present.
In addition, "emission model" that is not non-emission type has "laser method" "microwave method" "ultrasonic system".

Merit demerit of wireless Charge Qi

Merit demerit of wireless Charge Qi

When we charge smartphone as before, we do not connect cable every time and finish if we do wireless Charge using Qi. There seems to be only merit if we see only one point, is there not demerit?
Here, we introduce merit and demerit of wireless Charge using Qi.

Merit of wireless Charge

At first, we will see wireless Charge and merit by type of wireless battery charger.

Merit of wireless Charge

・We can charge just to put without cable

We just put on the top, and wireless Charge can charge cable to connect smartphone and battery charger to without need. When we lift from battery charger when we put to battery charger, it does not have to pull cable using both hands, and to put, and to do and can easily perform that there is not cable with one hand.

・As there is not cable, we can charge different model

Even if it is USB Type-C that there is not cable even if connection terminal of smartphone is Lightning, we do not matter. Regardless of type of terminal, we can charge if it supports even Qi.
If smartphone of friend and acquaintance supports Qi even if we do not have cable, we can lend battery charger.

・There is battery charger which can charge several

As we can charge if it supports even Qi, that can plurally charge even different model at the same time, too. It becomes condition that this is wireless battery charger which can charge several at the same time, but, as for the cases using plural smartphone for at home, it will be big merit.

Demerit of wireless Charge

We introduce wireless Charge and demerit in conjunction with type of wireless battery charger successively.

Demerit of wireless Charge

・Charge is slow

Wireless Charge biggest demerit is point "that Charge is slow" in. This is not connected to power supply directly and is one caused by thing that is inefficient because we just generate electricity using structure of magnetic field.
Furthermore, it becomes later when supply capability of wireless battery charger is low. For example, we cannot charge at original speed if the wireless battery charger side cannot supply electricity of 7.5W in the case of iPhone 8 which high-speed Charge can play.

・Position to charge is severe

When there is gap between side transmitting electricity and side to receive to use electromagnetic induction method, we cannot charge Qi properly. Therefore we have trouble "that position slips off if relieved to put on the battery charger, and is not charged at all".
Particularly, Dimensions of smartphone does not have limitation, but on the other hand Caution is necessary for wireless battery charger of pad type as gap of position is easy to take place.

・Dimensions of smartphone influences depending on type of wireless battery charger

Because we are fixed to decided position, as for the stands type and the holder type, problem of position gap of smartphone does not happen. However, there is demerit to choose device to install.
If it is only smartphone, we may not have any problem, but are unsuitable, for example, to charge something like Wireless Earphones "AirPods" of Apple.

・Case and accessories interfere with Charge

In the case of smartphone to use in private, there will be many people customizing appearance and convenience with case and accessories. However, depending on type of case and accessories, it may disturb Charge.
It seems to be easy to influence Charge basically as "thing disturbing magnetic field generation" causes problem occurrence when case and accessories have metal parts.

We compare demerit with merit, and let's decide introduction of Qi

Wireless Charge using Qi is not only merit as introduced. Particularly, lateness of Charge will become considerable stress depending on people. However, Charge is completed on the next morning if we set before going to bed. In addition, trouble of Charge such as gap of position should warn by oneself, and case and accessories should use thing which there is not of problem, too.
Therefore you compare demerit with merit and you judge whether wireless Charge is necessary for own how to use and should decide introduction.

We compare demerit with merit, and let's decide introduction of Qi