Recently, foreign media exposure said Samsung's flagship Galaxy S9 mobile phone next year has officially abandoned the under screen fingerprint scheme, and will continue to use the fingerprint unlocking scheme behind it. But even with the current Face ID first edge of apple, also challenged screen fingerprint technology fails. So, how difficult is the fingerprint technology under screen, unexpectedly so many technology giants bow?

At present, fingerprint identification has become the default scheme for most smartphones. From the technical point of view, fingerprint identification has several solutions, such as capacitance, optics and ultrasonic. Since iPhone 5S, the capacitance fingerprint identification scheme has become the mainstream. At present, almost all mobile phone fingerprint identification is the capacitance scheme. The principle of the work is to use the Home key of the mobile phone or the capacitance sensor on the back of the fuselage to collect the information of the user's finger pattern. The function of living body detection can be realized by adding the thermal sensor in the capacitance scheme.

Because of its small size, low cost and fast unlocking, the capacitance scheme is the preferred unlocking method for the intelligent machine. However, since Samsung's Galaxy S8 began to popularize the concept of "full screen", the pre capacitive fingerprint identification program had encountered a problem: it is difficult to place capacitive fingerprint identification sensors on the screen to identify user fingerprints.

The capacitor scheme crashed, many companies can only focus on the solution of other stronger penetration, such as ultrasonic and optical scheme. Optical scheme refers to setting up optical sensors at the bottom of the screen, identifying the fingerprint pattern of users through emitting near infrared light, which is similar to Apple's structured light scheme. And the ultrasonic scheme, as the name implies, is to set the ultrasonic sensor under the screen to complete the fingerprint recognition by ultrasonic.

In the mobile phone industry, all two solutions have followers. In February this year's MWC conference, Shenzhen's top technology showed a Samsung S7 Edge equipped with optical fingerprint identification scheme. However, this scheme is not yet mass produced.

The practitioner of the ultrasonic scheme is the Qualcomm Corp at the top of the world. According to the data provided by Qualcomm, its ultrasonic fingerprint recognition technology can penetrate 1200 micron thick OLED screen, 800 micron glass and 650 micron aluminum alloy. At the end of June this year, vivo has demonstrated the ultrasonic fingerprint scheme is equipped with Qualcomm's prototype, but the site experience is not satisfactory. According to Qualcomm, the ultrasonic scheme still has the problem of large volume, recognition rate and low recognition speed.

Zhang Fan, chief executive of Hui Ding technology, recently said in the media interview that the under screen fingerprint technology of the company is still under development, and the team has invested in this technology for three or four years. However, Zhang Fan did not reveal the real production time of its fingerprinting technology. According to the media, high Qualcomm ultrasound fingerprinting can be mature early next year, and the earliest measure of production will have to wait for the two or three quarter. This means that the Samsung Galaxy S9 released at the beginning of next year is destined to have no underlying screen fingerprint scheme, and the Galaxy Note 9, which may be released in the autumn, has the opportunity to take the lead in adopting the new solution.

In addition to the fingerprinting scheme, many leading companies in the industry have begun to develop a 3D facial recognition scheme that is similar to the iPhone X's Face ID. High pass and Himax, Orbbec, and Mantis Vision are trying 3D recognition technology. Taiwan KGI analyst Guo Mingchi forecast, equipped with 3D recognition technology in the next two years the Android phone shipments is 2 to 3 times the use of mobile phone screen fingerprint, one important reason is the screen under the fingerprint must be equipped with OLED screen, 3D technology can be equipped with OLED or LCD screen. However, Guo also revealed that it would take two and a half years for Android phones to reprint the face recognition level of iPhone X.