With face masks becoming more common and affecting the effectiveness of Face ID, there have been reports that Apple may bring back Touch ID on the iPhone 13. Now, a new patent reveals what kind of innovation Apple is looking to make in this area.

Like many of its Android rivals, Apple's instinct seems to be to introduce a fingerprint sensor under the screen rather than bring back the home button. This is not something Apple has done before, but this patent, first discovered by Patently Apple, clearly indicates that this is an area the company is considering.

Catchily titled "Under-display fingerprint sensing based on off-axis angular light," the patent describes Apple's plans to make in-display authentication faster and more reliable It states. Rival optical solutions use light from the phone's screen to illuminate the fingertip, but Apple claims that due to "low light throughput and diffraction," readings tend to suffer from low contrast and weak signal-to-noise ratios, and are more inconsistent and slow than necessary.

Apple's alternative is to capture off-axis angular light from the finger via an "angle-dependent filtering option between the display and sensor," as shown in the image below. This patent should improve reliability (and thus speed) without adding extra bulk to the system.

The complex system Apple is considering is designed to allow "transmission of reflected rays from the surface to the underlying layer. This is combined with an optical coupling layer under the panel that "bends the reflected rays" for decoding by the pixelated image sensor after being picked up by the collimator layer.

What kind of technology is Apple planning for its devices? While a company's acquisition of a patent is no guarantee that it will be incorporated into a commercial product, all of the examples included in the text focus on OLED panels. This is the screen type used in the iPhone 12 series and will almost certainly be used again in the iPhone 13.

Apple analyst Min Chikuo predicted that such a feature could be included in high-end devices in 2021, and a report earlier this year also confirmed this, suggesting that Apple is ready to offer both Face ID and Touch ID in the next generation iPhone The report earlier this year confirmed this, suggesting that Apple was ready to offer both Face ID and Touch ID on the next generation iPhone.

While the new iPhone won't arrive until September, such technology could debut on a refreshed model of Apple's tablet due out next month. Indeed, last year's iPad Air reintroduced Touch ID, but for the first time Apple embedded it in the power button on the side of the tablet.