Apple patents fingerprint sensor that scans through iPhone screen
Apple has received a patent that covers a fingerprint sensor that can accurately read fingerprints through structures like a device screen that, according to a report by Apple Insider.
Initially filed in September 2014, the patented technology for a “Capacitive fingerprint sensor including an electrostatic lens” could resolve a major design challenge in the rumored design of next year’s iPhone.
Based on several reports, the 2017 iPhone will eliminate the home button and feature a “full-screen face” consisting of an edge-to-edge OLED display.
Instead of the physical Touch ID module built into existing iPhone and iPad devices, Apple is rumored to be developing a virtual button which would facilitate the same features and functions.
Although software commands can be replicated with graphical buttons, it was unclear on how , Apple would integrate its Touch ID fingerprint technology into an iPhone that lacked a home button.
The newly patented technology resolves these design issues by adding capacitive sensing technology that works through gaps in space, which allows the Touch ID module to be inserted underneath the iPhone’s display.
In common fingerprint sensors, a gap between the fingerprint contact surface and the capacitive sensing array causes a blurring in the finger’s electric field which can result in a depreciation in fingerprint image resolutions and reduced recognition accuracy.
To prevent this, Apple will use electrostatic lenses (one or more patterned conductive layers) that will enable the layers to shape or bend the electric field associated with a user’s finger.
In some situations, this bending can offset the natural dispersion of a finger’s electric field as it moves through a dielectric layer or space.
Apple compares the electric fields associated with certain points on a finger to cones, which are subsequently dispersed from their respective peaks and blend with each other to create the previously-mentioned blurring effect.
Electrostatic lenses are adjusted to receive an unshaped cone and generate shaped versions that are then distributed across various sensing elements to create an accurate image of a user’s fingerprint.
Apple notes that there is one issue related to the electrostatic design in that it requires a drive ring to provide an AC or DC voltage to a user’s finger, electrically combining the digit and providing a predetermined potential difference between it and the sensing array. Apple’s existing Touch ID module uses a similar solution.
The patent application also describes several other potential system configurations, including single-pattern solutions and installations with multiple sensors, as well as other scenarios in which an electrostatic lens is used to improve blurring caused by displays.
Previously reported, Apple received a U.S. patent relating to its Touch ID biometrics feature.