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Big Restrictions Of Fingerprint Sensor Under The Screen

4 min read

Fingerprint sensor on Galaxy S10, OnePlus 6T or many smartphones from Chinese firms are no longer located behind the back or front, it is brought down below the screen. However, this technology has many limitations that can lead to discomfort when used, especially when you have just bought the device.


Hard to locate

This is the first feeling you see when you use S10. Since the whole screen is all black from the top to the bottom when the device is in difficulty, you won’t know where you need to put your finger. Only when you press a button to brighten up the screen, the fingerprint icon on the screen will appear, but then there is no meaning anymore because you have to do up to 2 operations to open the machine.


This is a major limitation of fingerprints under the screen compared to fingerprints on the home button or fingerprint on the back. Because the design of the traditional fingerprint sensor often has a recessed hole or a knurled button, it is easier to locate, and not afraid of missing.


This feeling is sure and more confident than when using the fingerprint sensor under the screen.


On the Galaxy S10, I need a few hours to get used to the finger placement when the screen is locked, but sometimes I still miss it when I use it.



There are currently two technologies for fingerprint sensors under the screen: ultrasound, and optics. Optical sensor is the type used for OnePlus 6T, Vivo, while the ultrasonic sensor is the one that Galaxy S10, S10 + are using. The optical sensor records your fingerprint by capturing your fingers, calculating the number based on concave convex lines and comparing it with previously registered finger data. Ultrasound sensors record the indentation with ultrasound, the latter is the same as above.


It is worth mentioning that both fingerprint sensor technologies below this screen are slower than capacitive fingerprint sensors, which we can see on most smartphones today. Capacitive fingerprint sensor has had a long time to develop so the recognition speed is much faster. On the S10, I sometimes have fingerprints that cannot be detected, and I have to scan them again and again to get them done. In addition, the time you have to put your hands on the screen for a longer time is not the same as the traditional capacitive sensor that touches the transmitter.


For you with wet fingers, the ultrasonic fingerprint sensor will be easier to identify than capacitive sensors, this is a plus. But speed is still a problem.

Not all screen stickers are usable

If you like to paste the screen, the fingerprint sensor below the screen will make it difficult for you. Only new plastic stickers allow the sensor to function normally, while toughened glass is different, not all can be used. This is the reason why the Galaxy S10 is available when you sell it. For a guy who never uses a sticker like me, this is not a problem, but if you buy a device, remember to pay attention.

Better solution: face, or fingerprint screen

After using all biometric security measures on the market today, I still like the most to recognize the 3D face, which is being used by iPhone X, Huawei Mate 20 Pro and Xiaomi Mi 8 EE. Face recognition mechanism is so easy and fast that you don’t need to remember to unlock your phone! You just need to pick up the phone, swipe from the bottom of the screen one by one to go to the main screen inside, Face ID runs automatically and very quickly so you almost no longer feel that the device is secure.


With operations you have to do a lot of times a day, it needs to be as simple as possible, and only identify the face that does it until now. Traditional fingerprint sensors, fingerprint sensors under the screen, or iris recognition all require you to interact with the machine in some way, otherwise it won’t work, and you can see that not many firms Android can achieve the good experience as expected.


Another hope for the future is that the fingerprint sensor technology can be used anywhere on the screen. This technology is being tested by Xiaomi, hearing rumors that Samsung and LG are also studying this special platform. At that time, you don’t need to place your finger on a certain position, and instead scan for fingerprints anywhere. It will take 1-2 years for this technology to appear on commercial products.


During that time, I will prioritize the selection of devices that recognize 3D faces when buying high-end phones.