Some users with screen fingerprint phones may notice that, In strong light, it seems that you can vaguely see a regular pattern in the fingerprint identification area?
Behind all this, Is it the distortion of human nature or the loss of morality? Is it an attack of wheel eye? Or pupil overflow? Welcome Love to play computer games This issue is about science popularization.
The purpose of this science popularization is to answer three questions: Can you see it? Why can I see it? And simple screen fingerprint science popularization.
Off screen fingerprint model
Although non-contact biometric recognition schemes such as 3D structured light face recognition and ToF structured light have emerged, in the eyes of many computer users, screen fingerprint is the unlocking scheme of the next era. Some people even think that the reason why Apple switched to 3D structured light is that the screen fingerprint scheme could not catch up with the release of new machine nodes.
Before the release of iPhone X, Apple and Samsung were the first to launch screen fingerprints. For Samsung, it has been rumored since last year that the former flagship Galaxy Note8 will be equipped with screen fingerprints. As a result, Note 9 has no screen fingerprints.
On the contrary, the progress of domestic manufacturers is fast:
Vivo showed the prototype of ultrasonic screen fingerprint last year, and then selected the optical screen fingerprint scheme, Now there are three X20 Plus UD, X21 UD and NEX flagship versions Mobile phones that use optical screen fingerprints have also passed the 3rd generation optical screen fingerprint scheme.
And just launched Xiaomi 8 transparent exploration version , and the Meizu 16 series (The second generation screen fingerprint) and other new computers are also equipped with optical screen fingerprint. Among them, the former is still the only pressure sensitive screen fingerprint model.
Can you really see the fingerprint module under the screen with strong light?
Xiaomi 8 transparent exploration version, fingerprint indication area during screen rest
In strong light, the screen fingerprint module of Xiaomi 8 transparent exploration version
X21 UD screen fingerprint area under strong light
NEX screen fingerprint area, under strong light, the very small dot in the middle
It can be seen that the second generation of underscreen fingerprint sensor of vivo X21 UD has lower visibility under strong light than that of Xiaomi 8 transparent exploration version, and is better hidden. The best hidden and smallest is the third generation screen fingerprint of the flagship version of vivo NEX, which has only a small circle and is difficult to find with the naked eye.
Then, we light up the screen to see:
The screen fingerprint module of Xiaomi 8 transparent exploration version is bright under strong light
X21 UD screen fingerprint, bright screen status under strong light
Left X21 UD, right Xiaomi 8 transparent exploration version, solid color image under strong light
Left X21 UD, right Xiaomi 8 transparent exploration version, set the interface under strong light
The screen of NEX flagship is lit under strong light, and the fingerprint area can hardly be seen
Under strong light, it is easier to see the screen fingerprint module under the screen when the screen is lit:
The screen fingerprint identification areas of Xiaomi and vivo X21 UD are similar in size, but Xiaomi's sensor is tilted (In order to increase the effective area when unlocking with the right hand?);
Xiaomi's pressure sensitive screen fingerprint, There is a large area beside the sensor, and the overall contour should be clearer.
Then, let's compare the disassembly of the screen fingerprint module of several mobile phones:
The transparent exploration version of Xiaomi 8 disassembled by Sina is the screen fingerprint module in the middle
Vivo X21 UD disassembled by Zhongguancun
The screen fingerprint module on the flagship version of NEX is much smaller and adopts a camera like design
After disassembling the screen separately, you can see the light transmission holes on the NEX flagship screen
Why can I see it? Small science popularization of screen fingerprint principle
In the final analysis, screen fingerprint is the technology of putting fingerprint identification module under the screen. Now the two most mature directions of screen fingerprint are, They are Qualcomm's ultrasonic solution and the mass produced Zenith/Xinsi optical solution:
Qualcomm's ultrasonic solution can be traced back to the ultrasonic fingerprint on LeEco mobile phones and Xiaomi 5s. It is one of the "black technologies" that Xiaomi 5s glass can be used for fingerprint identification without opening. In vivo's testing machine last year, the ultrasonic module was finally placed under the screen. In the ultrasonic scheme displayed at that time, Qualcomm PPT claimed that the penetration could be better than the optical scheme, and it could be used under the thicker LCD screen module without fear of water. Many people thought that it would be the mainstream, but in the end, because of the recognition speed, volume, cost and other reasons, it has been largely abandoned by the optical screen fingerprint scheme.
In mass production machines, only optical screen fingerprint can be seen now. The principle of the optical scheme is a bit like the traditional fingerprint punch. First The fingerprint is illuminated by the light of the OLED screen itself, and the optical fingerprint imaging is completed by the CMOS/CCD sensor below the screen, or even the fisheye camera (NEX flagship).
The first screen fingerprint sensor in the world was the Clear ID FS9500 released by Synaptics in December 2017, and then Huiding Technology in China followed up with products with similar performance. It is said that the recognition rate of the Huiding version will be slightly weaker, but because most models are mixed with Huiding and Xinsi, we haven't been able to get the same model with different sensors for the time being, so we can't verify it, for reference only.
Having said that, we can basically answer the first question. Optical screen fingerprint The sensor under the screen needs to receive the light penetrating the screen, which inevitably requires improving the light transmittance of the screen. Conversely, it is very natural to see the sensor below the screen in strong light.
In order to improve the recognition rate of screen fingerprint and reduce the refraction, scattering and other optical interference when light penetrates the glass cover, the glass cover needs to be very thin and has good light transmittance. "Collimator Hole" is added to the screen fingerprint on the top of the sink to better focus the light on the sensor under the screen.
Will it affect daily use?
The answer is almost never . There are two reasons:
First, the strong light environment in the above picture is under the sun, Normal people are unlikely to use mobile phones for a long time in such a bright environment . It is difficult to see the interior of the screen under normal brightness.
Secondly, after all, the screen itself is a illuminant. Only when the ambient light is much brighter than the screen, the light that penetrates the screen and shines on the screen fingerprint sensor, and then reflects can be detected by us. If you like to explore, it is recommended to use a strong flashlight to illuminate, so that you can easily see the holes under the screen.
Instead, for X21 UD, Xiaomi 8 transparent exploration version, and Meizu 16 series just released, these products use the second generation or near principle optical fingerprint solution. If the module cannot be seen clearly under strong light, it is more difficult for the module to collect fingerprint information, It will affect the recognition rate and speed. It's really a dilemma. This may be the reason why the third generation screen fingerprint on the flagship version of NEX needs to be greatly changed.
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