Want to say goodbye to the Home button? It's not as easy as you think

Nowadays, there are fewer and fewer buttons on mobile phones, and manufacturers are eager to cut off all interfaces and buttons. Imagine if there is only a screen on the front of the phone, just like Xiaomi MIX, which brings people only surprise and visual impact. To achieve such a beautiful setting, the first problem is to solve how to deal with the popular fingerprint recognition Home button. Synaptics has done a little work for this. The third-generation Natural ID glass inner layer (under-glass) fingerprint sensor Natural ID FS4500 has been sampled since September. Under the new solution, fingerprints can be scanned directly through glass and ceramic buttons.

In fact, the Natural ID FS4500 solution has the same goal as Qualcomm's Snapdragon Sense ID ultrasonic fingerprint recognition technology, which can abandon the past practice of "digging a hole" on the glass to install the fingerprint recognition module, and can prevent dirt from entering the fingerprint recognition module through the gap and affecting the accuracy. Synaptics and Samsung have always been good friends, and it is possible that Samsung will be the first to use the fingerprint recognition module of this technology, but the module size of the FS4500 solution is 6*6mm, which is too large for Samsung's flagship mobile phones, resulting in a decrease in the screen-to-body ratio. I believe Samsung will not use this module.

Digging a hole represents

However, just like the Home button of Xiaomi 5s, unlike the previous mechanical Home button that can be pressed, it is operated by light touch, so a new set of system interaction operations needs to be designed.

On the other hand, the Natural ID FS4500 solution only supports 300 micron (0.3 mm) glass cover. According to the current requirements of mobile phone manufacturers for screen glass thickness, the glass above the Home button still needs to be "thinned". Although the aesthetics have improved, it is still not perfect. In contrast, Qualcomm's ultrasonic fingerprint recognition technology can support penetrating 400 micron glass and metal layers to detect the "ridges" and "valleys" on fingerprints. Even so, like the solution used by Xiaomi 5S, the Home button still has a "pit".

Grind pit representative

This solution does help improve aesthetics and durability, but it is by no means the final form. The ultimate goal of fingerprint recognition is to complete fingerprint recognition anywhere on the screen as long as you place your finger. Previously, common capacitive recognition failed in this regard, because capacitive recognition technology needs to work by detecting tiny changes in the electric field, but it will be strongly interfered by noise when placed under the screen; the acoustic principle used in ultrasonic recognition, although extremely sensitive, has problems with high power and cost; optical sensing technology does not have a recognition distance problem, but requires a closed and opaque frame to provide a good recognition range, but there is currently no solution.

At present, there is no good solution for capacitive recognition, optical recognition, and ultrasonic recognition. There is still a long way to go to break through the seemingly thin glass "barrier" and realize the ultimate form of fingerprint recognition. Perhaps there will be more black technology in the future. Let us wait and see the perfect Fingerprint in Display mobile phone.

As a winner of Toutiao's Qingyun Plan and Baijiahao's Bai+ Plan, the 2019 Baidu Digital Author of the Year, the Baijiahao's Most Popular Author in the Technology Field, the 2019 Sogou Technology and Culture Author, and the 2021 Baijiahao Quarterly Influential Creator, he has won many awards, including the 2013 Sohu Best Industry Media Person, the 2015 China New Media Entrepreneurship Competition Beijing Third Place, the 2015 Guangmang Experience Award, the 2015 China New Media Entrepreneurship Competition Finals Third Place, and the 2018 Baidu Dynamic Annual Powerful Celebrity.