A new phone from Chinese maker Vivo has its fingerprint reader embedded in its screen, using a technology from Synaptics. (Geoffrey A. Fowler/The Washington Post)

LAS VEGAS — As smartphones go all-screen, one design problem has bedeviled everyone from Samsung to Apple: Where to put the fingerprint scanner?

At CES, a big tech component maker showed the first phone to try something new: putting it inside the screen.

Other all-screen Android phones like the Galaxy S8 and Pixel 2 moved the fingerprint sensor to the back of the phone, which some find awkward. Apple dropped the fingerprint-reading home button entirely with its iPhone X, opting for a face scanner that some (like me) find fails just often enough to annoy.

The fingerprint reader behind the screen on Vivo's newest phone is fast and easy to use. (Geoffrey A. Fowler/The Washington Post)

That’s why I was curious to try out the new Clear ID tech that maker Synpatics has been demonstrating at CES. It embeds the reader inside the screen, and is coming first to a phone from big Chinese phone maker Vivo early this year.

Using it was as natural as you would want it to be: I just held my finger over a lit-up area on the Vivo phone’s screen, and it unlocked quickly and consistently. (I also had success with a colleague’s finger.) There's always a bit of the screen on, so you can find the right spot.

The inside-the-screen tech has a rejection rate of about 2 percent, and a false acceptance rate of 1 in 50,000, both typical for the industry. Synaptics CEO Rick Bergman said it took 18 months to turn the tech from a demo into a real product that could handle issues such as dry fingers and sunlight.

This optical fingerprint sensor tech only works behind OLED screens because they’re sufficiently thin and transparent. Synaptics rival Qualcomm has announced they’re also developing a behind-the-screen reading tech, but it has yet to arrive in a finished product.

When will this tech show up on phone retailed in the U.S.? “You can certainly say every phone maker has been stopping by,” Berman said.

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