Back when rumors were swirling about Apple's iPhone X, the prospect of where the Touch ID sensor for the device might end up was just one of the open questions. As it happened, the company eventually went so far as to basically miniaturize a Kinect, nestled it into the infamous notch, and called it Face ID. Apple's senior vice president of hardware engineering later claimed that Touch ID was never even in the running for the iPhone X once Apple developed its facial-authentication tech. That outcome doesn't mean an under-glass fingerprint reader isn't a cool idea, though. As a guy with a twin brother, facial-identification tech is potentially insecure for my ugly mug. Touch ID and its ilk are still my preference, and a phone with both an edge-to-edge display and a front-mounted fingerprint reader would immediately grab my attention.
An example Clear ID FS9500 scanner. Source: Synaptics
The human interface wizards at Synaptics seem poised to make that combination possible in some of the wide range of "infinity display" Android flagship phones set to arrive in the near future. The company's Clear ID FS9500 family of fingerprint scanners, launching today, promise all the convenience of a front-mounted fingerprint scanner without the need for a button to house it or a bezel around that button. With one of these sensors underneath a display, folks might be able to have their infinity-display cake and eat it, too.
The way the Clear ID sensor works seems rather novel. To start with, the sensor has to be paired with an OLED display. When it's activated, an FS9500 sensor will use part of the OLED panel above it to illuminate the print of the finger resting there. The light reflected by the user's finger then passes back through the substrate of the OLED display to be processed by the sensor itself. Synaptics claims that its sensor can work as the bottom slice of bread under a meat stack of display components up to 1.5 mm thick, and that it can be integrated with OLED screens using standard optical production materials and processes.
Sensing the finger is just one concern with biometrics, of course. Synaptics promises that users' biometric information will be protected by its SentryPoint suite of security and anti-spoofing technologies. The FS9500 can adaptively improve recognition of a user's fingerprint, resist reproductions of a user's print, and protect information in transit from the sensor to the host using TLS, AES encryption, and ECC to ensure security and authenticity. The company also notes that because the sensor is embedded under the display, it's much better poised to resist moisture, abuse, and grime than an externally-exposed button.
A camouflaged version of the production phone with Synaptics' under-display fingerprint sensor inside. Source: Synaptics
Although the company didn't announce any design wins today, it says it'll be demonstrating an in-production, soon-to-be-announced "Tier 1" phone with the sensor on board at CES 2018. If you notice a flood of phones with under-glass fingerprint scanners on board next year, it's a likely bet that many will be built around an FS9500 sensor of some kind. Stay tuned.