HONOR Magic 4 - The Ultrasonic Fingerprint Sensor

The new HONOR Magic 4 implements, among many views, one function that, currently, only the top of the category have: the ultrasonic fingerprint reader. Let's see what it's about.

Brief historical notes

Every year smartphones evolve into something, becoming more and more technologically advanced not only in terms of new functions but also in terms of security.

Since the iPhone 5S with its fingerprint reader came out in 2013, most smartphone manufacturers have pledged to bring the same technology to their devices, which only allowed those who had registered their fingerprint to access the device. 

No more pins or passwords then, but it was enough to place your finger over the sensor to unlock the phone.

The main types of sensors for fingerprint detection

• Capacitive

• Opticians

• Ultrasonic

Capacitive sensors

Capacitive sensors are the most common ones because they are the most dated and therefore tested.

Virtually all fingerprint sensors not integrated into the screen are capacitive. The name is due to the way it is made, they use electric current to read a fingerprint using a series of extremely small capacitors (also called capacitors), each of which has a very small electric charge.

Think of the sensor made up of the squares (capacitors) on a checkerboard, only on a tiny level where each capacitor is smaller than the width of a fingerprint ridge.

Each capacitor includes two conductive plates that come into contact when a crest of the impression comes into contact with the sensor. Connecting the two plates changes the amount of charge that a particular capacitor has. And wherever there is a valley in the footprint, the charge in that specific capacitor remains unchanged.

This system allows you to create a footprint map based on which capacitors have a specific amount of charge and which do not. The touchscreen of the displays works in a similar way, but the sensors work on a much more detailed level.

Optical sensors

With this solution, the device gains in aesthetics as it remains more "clean", but also the activation of the release gains as the pressure of the sensor being on the screen is easier to reach.

Optical sensors are much easier to understand because they use a simpler method of enrolling the smartphone owner's fingerprints: they take pictures of the fingerprints.

The sensor illuminates the fingerprint with a small LED light, then a camera takes a quick snapshot capturing the light and dark areas that respectively denote the ridges and valleys of the fingerprint.

Optical sensors are less secure than capacitive ones (a photo is enough to deceive them) can be integrated under the display of a smartphone, allowing you to create full-screen smartphones.

But there are also other disadvantages, for example, a scratched touch surface or a dirty finger can cause the fingerprint not to be recognized.

The ultrasonic sensors

Ultrasounds are very high-frequency sound waves able to penetrate the epidermal layer of the skin that shows the same characteristic pattern of the fingerprint (furrows and ridges). The measurements of the reflected sound wave can be used to form an image of the footprint, the ones that return first represent the ridges, the others the grooves, it is a sort of ultrasound of the fingerprint.

The sensor can detect mechanical stresses to calculate the intensity of the ultrasonic return pulse at different points of the scanner, ultimately generating a highly detailed 3D reproduction of the scanned fingerprint.

Qualcomm which manufactures ultrasonic-type fingerprint scanners. Known as Sense ID, this type of scanner supports smartphones equipped with Snapdragon 855 processors. Qualcomm's configuration is also designed to support Fast Identity Online (FIDO) protocols, which can be used for online authentication without having to use a password. . FIDO does this without transferring any confidential fingerprint information to the cloud or across networks that could be compromised.

According to Qualcomm, there is a latency of 250 milliseconds to be able to unlock the device.

Another important implementation for mobile devices and therefore

HONOR CAN DO