The Vivo under-display fingerprint technology is based on Qualcomm’s ultrasonic fingerprint sensors. It eliminates the need for manufacturers to place a dedicated sensor on a smartphone as it injects the ability to unlock or authenticate from underneath the surface of the phone. The new type of authentication is supported and the sensor can now work through OLED display stacks up to 1.2mm thick, up to 0.8mm of a cover glass, or up to 0.65mm of aluminum (an increase from 0.4mm for both glass or metal). It also works when wet or greasy, unlike the capacitive fingerprint sensors we find on phones today.
— Richard Lai (@richardlai) June 28, 2017
According to Lai:
“I found the fingerprint recognition speed to be noticeably slower — about one second between first touch and entering home screen — than the near-instantaneous unlock that I’m used to on most recent smartphones.”
How does it work?
Vivo Smartphones uses an ultrasonic sensor underneath a surface (display or rear panel). For authentication, piezoelectric effects (in simple terms, the mechanical stress or the pressure put on the surface) are used to exchange ultrasonic signals which travel through the OLED screen.
Once the ultrasonic signals travel through the OLED screen, they create a 3D map of the fingerprint under the display. Consider this as a sound wave traveling through compatible surfaces and creating unique fingerprint-based identities with the help of software.
Once the ultrasonic signals travel through the OLED screen, they create a 3D map of the fingerprint under the display. Consider this as a sound wave traveling through compatible surfaces and creating unique fingerprint-based identities with the help of software. At the event, Vivo showcased a prototype device exploiting the technology. By putting mechanical stress or pressure on a designated area of the display, the fingerprints are registered and authentication is carried out.
It is also worth noting that the Vivo under-display technology is said to work with metal, OLED display, and also a certain type of plastic. It can not only be embedded under the display but also behind the metal shell or even in the frame, as Vivo suggests.