I put my thumb on the display of a dummy smartphone. A tiny, imperceptible blast shoots out of the equipment, blocking the ridges and valleys of my finger and confirming my identity.
In an instant, another phone connected to the dummy will come alive as soon as the homepage appears.
Standing in a conference room in the heart of Qualcomm's San Diego headquarters, I'm trying out an early ̵
The technology is the same as DJ Koh, head of Samsung's Mobile Business, demonstrated at an event in China this week. And while Qualcomm refused to comment on any specific phones that use the technology, and Samsung remains mother to what will emerge in the Galaxy S10, any phone that includes ultrasonic waves to read a fingerprint needs to work with Qualcomm.
Embedding the fingerprint reader under the glass is the next step in verifying our identities and logging in to our smartphones. It is also a practical workaround for the trend to remove main physical keys and to enlarge the frame around the display. The larger the display, the more the phone manufacturers need to move the reader to the back of the phone or get rid of the Apple iPhone X in favor of a face recognition system.
The use of the fingerprint reader under the display was once considered a solution to the Holy Grail – mainly because it did not materialize after years of rumors. But they begin to appear, CNET gets a prototype of a Vivo phone with an in-display fingerprint reader in January and Huawei puts a reader into its special edition Porsche Design Huawei Mate RS phone.
Both the Vivo and Huawei phones use optical technology to scan the fingerprint through the display, a technique different from Qualcomm's. Regardless of the technology, it is expected that fingerprint readers will be on a grand scale next year. Consumer research firm IHS Markit predicts that by 2019, 100 million mobile phones will have fingerprint sensors on the screen.
How does it work?
Qualcomm uses sound waves to create a map of your fingerprint, with the shockwave bouncing off the various contours of your skin.
Ultrasound has some advantages, said Gordon Thomas, director of product management at Qualcomm. It can read a finger, even when it's wet, because the waves can read the liquid. It has a reject rate of 1 percent and a delay time of 250 milliseconds or comparable to traditional capacitive fingerprint readers on the Home buttons on the iPhone 8 or the Galaxy S9.
The sensor itself has a diameter of 0.5 millimeters, so the phone does not get much thicker. It can also work through glass or metal. In fact, a version of this technology is out there with the Huawei Honor 10, but the company decided to place the fingerprint reader in the glass chin under the display.
Finally, the ultrasonic waves can also be used to track blood flow and heart rate.
The alternative optical in-screen readers are built by the likes of Synaptics and Goodix. Instead of sound, they use light waves to image the fingerprint, but they can be dropped by different light conditions and water. Goodix technology supports the Mate RS, while Synaptics and Goodix are also used in Vivo and Xiaomi phones.
"We already have reliable and powerful solutions for multiple smartphones in retail," said Synaptics spokesman David Hurd on Qualcomm's recommendation that his technology was superior.
A Goodix spokesman could not be reached for comment.
Where are ultrasound smartphones?
Qualcomm introduced this fingerprint technology last June, but few smartphones have publicly accepted it.
That's because the ultrasonic waves, according to Gordon, only work with flexible OLED displays. Phones that are more commonly used are so-called rigid OLEDs, which have no air gaps required for these pressure waves.
Honor 10, for example, had to put the reader in the glass area below because it would not work through the display.
It's so difficult to get a flexible OLED display for a demo unit, so Qualcomm does not even have a working prototype, so its engineers had to combine a dummy phone with another smartphone for my demo.
There are only two companies that use flexible OLED displays on a large scale: Apple and Samsung. Given Apple's litigation with Qualcomm, that's an unlikely customer.
This brings us back to Samsung.
The Korean tech giant uses the right display technology and could use another Gee-Whiz feature when announcing its 10-year-old Galaxy S smartphone.
Talk about making waves.
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