Can mobile phones and cards be put together?

Can the card be demagnetized with the cell phone？

We often hear people say not to put mobile phones with ID cards and bank cards together, otherwise it will be demagnetized. So can the mobile phone really degauss the ID card?

Magnetic stripe card will be demagnetized by magnet

People usually say that the bank card is demagnetized, which usually occurs on the magnetic stripe card. Once the magnetic stripe card is close to a strong magnetic field, it may be abnormally magnetized, which is what we call demagnetization. Does the mobile phone have such a strong magnetic field? The answer is definitely not available, because the frequency of electromagnetic waves emitted by mobile phones is between 850MHz in the UHF band and 2.4GHz in the microwave band. In this frequency range, the main energy form of electromagnetic waves is electric field, which is not enough to generate and change card magnetic stripe information Magnetic field.

Someone said: "No? I used to put the card and the mobile phone together, and there was a degaussing situation." There are not a few people who have similar situations, but this is not caused by the electromagnetic waves emitted by the mobile phone. In fact, the real culprit is the speaker of the mobile phone, that is, the speaker magnet of the mobile phone. Everyone knows that there must be a magnet in the speaker, and the magnetism of the magnet is very strong, especially in the previous non-smartphones, the speakers are made very large, and the magnetism of speaker magnet is also very strong. It does not matter if you can attract a coin or a key. under. So if we put the magnetic stripe card and this kind of mobile phone together for too long, it will be demagnetized. However, the speakers of current smartphones are made very small, and naturally, the speaker magnet magnetism has become very small, and most mobile phones have speakers built on the bottom of the phone, unlike the previous ones. Therefore, sticking the card and the mobile phone together will not touch the speaker of the mobile phone.

IC card will not be affected by mobile phones and magnets

Common IC cards are divided into contact IC card and non-contact IC card.

Contact IC card

Nowadays, most of them are contact IC cards. Our mobile phone cards are also of this type. Its advantage is that it is not afraid of magnetic fields and will not be demagnetized. Its data is retained in the built-in chip. The device is completed by touching the yellow metal sheet on the card. 

Non-contact IC card

Our ID cards, bus cards,  and community access cards are all non-contact IC cards. Its characteristics are: you can’t see or touch its chip, but we only need to turn on the flash of the mobile phone and face the ID card. Take a picture and you can see the chip inside. How is the ID card sensed? The ID card is surrounded by a coil. The induction device emits electromagnetic waves to power the chip, and then the data can be read through the coil, so the ID card is not magnetic.

If the ID card cannot read the data, it is usually caused by a broken chip or coil. There is also a situation where the chip circuit is burned due to high current. Therefore, we must avoid twisting force when using the ID card. Heavy pressure or placed at high temperature to prevent damage to the chip and coil.

Putting a card and a mobile phone together will not demagnetize in fact. Generally speaking, only a magnetic card with a magnetic strip on the back can be demagnetized. A card without a magnetic strip will not be demagnetized. Even if a card with a magnetic strip is placed with the mobile phone, it will not be demagnetized. Degauss.

Because the energy form of electromagnetic waves generated by mobile phones is an electric field, not a magnetic field, it will not generate enough magnetic force to change the information on the magnetic stripe on the card. The most common magnetic cards in life are cards, shopping cards, etc. These cards are embedded with magnetic strips to store information. When the magnetic strips come in contact with objects containing strong magnetic fields, the information stored in the magnetic strips will be destroyed and "disordered" "This failure is commonly known as "degaussing".

The methods to prevent magnetic card demagnetization include: as far as possible away from the high magnetic field around induction cookers, microwave ovens, TVs, refrigerators and other electrical appliances, and try not to contact mobile phones, computers, PDAs, magnets, Wenquxing, Businesslink, or metals that may be magnetic, etc. Put magnetic items together. Do not throw magnetic cards in messy bags to prevent sharp items from wearing, scratching or twisting or breaking the magnetic strips; do not store multiple cards close to each other, and do not place them back to back. Avoid magnetic strips Friction and collision with each other.

The locks of some small magnets used in bags will cause demagnetization if the card is kept close to the locks for a long time.

Will magnets affect mobile phones?

People are worried that magnets can destroy digital devices because there is indeed such a possibility in previous electronic devices. For example, CRT monitors and TV sets are easily affected by the magnetic field of strong magnets and cause distortion effects.

However, today's digital devices such as smart phones, televisions and monitors do not appear to be like this. But strong magnets can affect some functions of the smartphone.

Magnets do affect mobile phones, but they must be very strong to affect some of the phone's functions. In fact, there are magnets inside the mobile phone itself to achieve some functions, such as wireless charging, which will be affected by super strong magnets. In addition, the internal sensors of the mobile phone, such as the digital compass, will also be affected by the magnet and display errors.

Magnets with low magnetism (such as small magnetic blocks on mobile phone holsters, magnetic mobile phone holders, etc.) generally do not affect the functions of the mobile phone. The leather cases officially launched by many brands such as Huawei, Apple, and Xiaomi are dormant cases with magnets. When the leather case is buckled, the screen turns black, and when the leather case is opened, the screen becomes brighter. It can be seen that mobile phone manufacturers have also proved through experiments that magnets with smaller magnetism have no effect on the circuit board GSM signals and GPS navigation signals.

For the magnetic mobile phone holder, the Consumer Value Center also specially invited the professional mobile phone product testing laboratory (FIH) to test the mobile phone antenna signal, call quality and electronic compass function. The results showed that:

The result of the call quality test also shows that the magnet has no visible effect on the phone call.

The only effect is the compass pointer. Due to the changes in the surrounding magnetic field caused by the magnet, the compass pointer needs to be re-calibrated. After calibration, it can be used normally.

When using a magnetic mobile phone holder, you need to stick an iron sheet (also called a magnetic sheet) on the phone before it can be used, because the magnetic force of the bracket is not large enough to directly attract the phone. The magnetic sheet is similar to an anti-magnetic speaker. The magnet is equipped with an iron shell to prevent the leakage of the magnetic dangling. The magnetic field of the magnet will only leak inside the speaker, forming a closed magnetic field. Therefore, as long as it is not a super-strong magnet, the impact on the mobile phone is negligible.