Touch ID is no longer included in the iPhone X and XS family, but there’s a possibility that Apple is planning to reintroduce the technology. Face ID is a successful replacement technology, offering fewer false positives, compared to the Touch ID. However, there are some advantages of Touch ID. In some situations, users need to silently activate their phones. In classrooms or during meetings, it would be a bit awkward to activate the phone with Face ID. This could be a problem if users need to access an email from client urgently or download a learning material. Even so, one issue with the fingerprint sensor of the Touch ID, is that it takes up a portion of the display.
This compelled Apple to mount the Touch ID sensor on the back. A recent patent revealed that Apple is developing a new fingerprint scanning technology without sacrificing space on the front. Titled as Acoustic Pulse Coding for Imaging of Input Devices, the technology detects any object that comes into contact with the display using sound.
In short, when you press your finger onto the display, the technology could read your fingerprint using reflected sound. Acoustic transducers transmit sound signals, the moment you touch the display with your finger. These transducers will wait for and receive the reflected sound signals. An image resolver will generate the image of the fingerprint using the data.
When sound impulses come into contact with your finger, their reflection will be modified by the small ridges of your fingerprint. So, reflections will be unique for each person and they can be rendered into a fingerprint image. This technology offers a few advantages compared to the regular, touch-based fingerprint scanner. The system allows for a thinner device because transducers can be placed away from the display at the edge of the device.
Electrodes are also not needed for the technology to work, which reduces the overall complexity. Apple also says that the technology is more energy-efficient and processor doesn’t need to work as hard. Enough transducers could be placed at the front part of the phone to ensure more accurate results.