Now that edge-to-edge displays are commonplace on smartphones, the new holy grail for mobile engineering is the creation of the under-display fingerprint sensor. Not under glass — that's easy — but under the thickness of the glass plus display, something nobody has quite mastered on a production scale yet.
Yesterday Mashable brought us word of a new generation fingerprint sensor installed in a prototype Vivo smartphone. Today Engadget's Richard Lai got to test it out at a trade show in Shanghai. The sensor, as it turns out, is the latest ultrasonic fingerprint sensor from Qualcomm that now works through OLED display stacks up to 1.2mm thick, up to 0.8mm of 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.
But here's the rub, 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.”
To my eyes, it looks to be about as responsive as the fingerprint sensor found on the three-year-old iPhone 6.
While Engadget's headline says "Vivo beats Apple to an under-display fingerprint scanner," that's not quite true is it? Demoing an ultrasonic sensor in a trade-show prototype is not even close to creating a phone sensor that can be cost effectively mass produced at iPhone scale. Qualcomm and Synaptics have been trying to perfect their ultrasonic tech for awhile now, with Samsung famously failing to find a workable solution for the all-screen Galaxy S8 (forcing it to place the fingerprint sensor on the back). Apple's all-screen tenth anniversary iPhone might be delayed, with some pointing to the complexities of mass producing the under-display fingerprint sensor as a contributing factor.
If what Qualcomm is showing today is truly state of the art, then it presents an interesting tradeoff for Apple’s next flagship phone: offer owners a slow but convenient fingerprint sensor under the display, or give them a fast sensor awkwardly located on the back of the device. Decisions, decisions.