Apple Patents Under-Display Fingerprint Sensor Amid Face ID Rumors

Apple has been granted a patent for a way to use acoustic imaging technology to read fingerprints through display glass. The patent was published on Tuesday by the U.S. Patent & Trademark Office. The patent, 9,747,488, details a method for an “active sensing element” used in acoustic imaging systems. An acoustic sensor is notable because it wouldn’t require optical access to a fingerprint to work. Basically, it doesn’t need to “see” a finger to authenticate it and could be placed underneath display glass without any issues.

How Does It Work?

The method works by using a suite of acoustic transducers installed near the bottom of a device. These transducers would send piezoelectric signals — essentially pressure-based electric charges — to the top of a device’s display. The ridges of a finger would create a unique acoustic pattern which could be used to identify a particular fingerprint. Those signals could then be sent back to a sensor for authentication.

However, such a system has several simulations and difficulties. For one, piezoelectric components typically operate at fairly high voltages and can create spikes of electric current that could potentially be damaging to other components. Apple’s patent also details a way to mitigate these issues with a system of integrated transducer controls that can operate independently of each other.

Notably, this isn’t the first time that Apple has been rumored to be exploring acoustic imaging systems for biometric authentication. The USPTO published an Apple patent application in February that focused on the architecture of a similar system. It’s also worth noting that many of those inventors are the same as the one published today.

Touch ID or Face ID?

It’s an interesting development, especially in the midst of rumors that Apple will do away with Touch ID in favor of an advanced facial recognition system for its upcoming iPhone 8. While the premium flagship was originally rumored to sport an under-display fingerprint solution, most experts are now predicting that such a system won’t be on the iPhone 8.

And while today’s patent doesn’t exclusively mention any particular device, the limitations of an acoustic imaging system could hint at the specifics of the company’s problems with implementing under-display Touch ID. Earlier in the year, a display-embedded fingerprint sensor was reportedly one of Apple’s biggest design “bottlenecks.”

Apple’s rumored switch to Face ID as the primary — and possibly sole — method of biometric recognition has been met with some understandable skepticism. A best case scenario for Apple might be to install a backup authentication method on the device. But, currently, there’s really no evidence to suggest that a fingerprint sensor will be present on the upcoming flagship.

As usual, today’s patent isn’t necessarily representative of Apple’s future plans or of upcoming features on its devices. Indeed, as we get closer to the company’s September event, the odds of a display-embedded Touch ID system for the iPhone 8 are slim to none. Of course, Apple could surprise us, or it could be holding off on acoustic imaging tech for a future iPhone.