More than two months after Apple unveiled its next-generation iPhone 5S smartphone, complete with fingerprint-based Touch ID, the United States Patent & Trademark Office has published a patent application for the security feature.
Initially filed in May 2012, the "Capacitive Sensor Packaging" patent details the same system you'll find on any new iPhone 5S.
The technology includes "a responsive element" to detect the proximity of the user's fingerprint (the stainless steel ring surrounding the Home button) and a sensor hidden under a control button made of "an anisotropic dielectric material, for example sapphire," according to the application, which reads like a more scientific version of Apple's smartphone design website.
With Touch ID, users can register up to five fingers (from up to five different people), then simply touch the Home button to wake up the phone — no passcodes needed.
Based on the patent application, though, Apple also looked at alternative methods of proximity detection, including optical or infrared sensing. The Cupertino-based firm suggests that those approaches could be implemented in the future, as simply plopping your finger onto the device "can have the effect of limiting the design flexibility," the application said.
Apple hasn't ruled out the possibility, either, of integrating a fingerprint sensor into a "display element," which could allow for better dexterity and deeper security.
That same touch-screen sensor also showed up in an Apple patent application filed in May with the World Intellectual Property Organization. The 612-page document, first reported by Apple Insider, details other uses for the tech giant's fingerprint sensing technology, including user interface navigation and mobile payment processing.
In that WIPO filing, Apple suggests that Touch ID could be used to identify and process gestures, letting the Home button act as a sort of trackpad to move within and switch between mobile apps.