Xiaomi secures patent for all-screen fingerprint scanner

Under-display fingerprint scanners might have been cool when they first got introduced in phones, but nowadays they are nothing to write home about. We are practically in a stage where the tech is so cheap to implement that even more affordable devices can be found with it.

That being said, recent news of a newly patented technology by Xiaomi points at a possible future advancement in under-display fingerprint scanners. The patent was recently awarded to the tech giant by the Chinese national patent database and it describes an all-screen fingerprint reader. (via Gizmochina)

An all-screen under-display fingerprint scanner means that you wouldn’t have to think about where you are placing your finger anymore when unlocking your phone. Such a feature is without a doubt an excellent example of user-friendliness and quality of life improvements, but it is more complicated to achieve than you might think.

Xiaomi’s all-screen fingerprint scanner explained

At the base of this new under-display fingerprint scanner technology lie a multitude of infrared LED light transmitters, which are positioned below the capacitive touch screen layer. The transmitters’ job is, as you might have guessed, to transmit the light, which reflects onto your skin.

The reflected light then is read by a layer of infrared light receivers, sandwiched between the touch screen layer—the outermost layer of the display— and the aforementioned infrared LED light transmitters. Below all of these layers, the bottommost one is the AMOLED display itself.


In other words, if we would paint a mental picture of the whole display from top to bottom, it would be:

1. capacitive touch screen layer
2. infrared light receivers
3. infrared LED light transmitters
4. AMOLED display.

Now, admittedly this sounds cool, but it is still what is called an optical fingerprint sensor. There are other types out there, like the ultrasonic sensors found on some Samsung phones that are arguably quicker and safer. The issue with those, however, is the manufacturing cost. Also, getting the whole screen to be one huge ultrasonic sensor could likely prove much more difficult.