At 3 o’clock in the morning on the 21st, Taiwan time, Samsung held the 2019 annual flagship machine conference in the United States, and published a number of flagship machines such as the Galaxy S10.

At the opening of the conference, the heavy release of the Galaxy Fold collapsible screen phone was very eye-catching and was the highlight of the entire conference. Samsung also focuses on several features such as Infinity Flex Display, multitasking, and multi-function lens combinations.

However, this year’s flagship release of Samsung will have more attention to the “new trend”, which may bring subversive changes to the biometric technology of the mobile phone industry – Samsung’s flagship Galaxy S10 and S10 Plus are the world’s first Qualcomm Ultrasonic screen fingerprinting technology for mobile phones.

In fact, at the MWC 2015 conference, Qualcomm launched the first ultrasonic 3D fingerprint technology solution for the mobile industry, namely Qualcomm Snapdragon Sense ID 3D fingerprint technology.

The mobile phone equipped with Qualcomm’s ultrasonic screen fingerprint technology seems to be very similar to the screen recognition technology scheme adopted by the 6T and Huawei Mate 20, but the technology is essentially different.

The Qualcomm’s ultrasonic screen fingerprint technology was first commercialized and mass-produced on Samsung’s terminal products, and it was beyond the expectations of others. Since the launch of the technology by Qualcomm, rumors of related applications and mass production have continued to spread on the supply chain. In October 2018, on the eve of the Huawei Mate 20 series presentation, Huawei’s public relations outflow evaluation script showed that Huawei’s Mate 20 series of under-screen fingerprint identification technology is Qualcomm’s ultrasonic technology. However, Huawei subsequently denied it.

Since the Samsung Galaxy S7, iris recognition has been applied to Samsung mobile phones. Today, Samsung is slowly abandoning iris biometrics. In particular, the Galaxy S10 and S10 Plus introduced the ultrasonic fingerprint sensor that marks Samsung’s built-in screen instead of the iris scanning sensor. At the same time, the Samsung entry-level mobile phone Galaxy S10 E also uses a traditional capacitive fingerprint sensor on the power button.

There are currently three types of fingerprint technology under the screen, namely capacitive fingerprint recognition, optical fingerprint recognition, and ultrasonic fingerprint identification technology. The former two technologies are more mature and are also applied to many manufacturers’ end products. Among them, optical fingerprint identification technology accounts for a large proportion of Chinese-made devices and is the most widely used.

Ultrasonic fingerprint identification technology and optical fingerprint recognition use fingerprint recognition to unlock the screen, and the operation process looks similar. So, what is the difference between the two technologies, how to distinguish which mobile phone is using ultrasonic fingerprint identification technology, and which mobile phone is using the conventional scheme optical fingerprint identification technology?

The concept of ultrasonic fingerprint identification technology

First, you need to understand what ultrasound fingerprinting technology is. Similar to Hospital Type B Ultrasound, the “3D Acoustic Sensor” technology works on the skin’s reflection of sound waves. Whether at night or during the day, sound waves can capture the details of the skin’s surface through the water, lotion, and oil on the skin.

According to Qualcomm, ultrasonic fingerprinting technology is safer and faster than optical fingerprinting sensors currently widely used in mobile phones. This is because the ultrasonic sensor captures the concave and convex texture of the user’s skin by 3D information. In contrast, optical fingerprinting does not transmit sound waves, but optically captures information, and only obtains two-dimensional image information.

Embedding a fingerprint sensor on a mobile phone screen is one of the hot trends in terminal design because it does not occupy any space on the surface of the phone. And the amount of technology required is less than that embedded in the phone’s power button and back sensor. This design works well with a full-screen phone and has virtually no borders.

In December 2018, Alex Katouzian, vice president of mobile technology at Qualcomm’s annual technology summit in Hawaii, said, “Safety and biometrics have been integrated into the mobile platform, which is the future direction of fingerprinting technology.”

The 3D sound fingerprint sensor developed by Qualcomm “reads” the fingerprint through the sound wave and unlocks the phone. From the current trend, the general fingerprint sensor is embedded in the display below the screen, so that the user can put the finger or thumb in the center of the screen to unlock the phone. Thus, it is also known as a screen fingerprint reader, and this type of sensor can also be built into the main key buttons of the device.

The ultrasonic sensor is integrated into one layer of the mobile phone display screen. When the user places the finger in the target area, that is, when the mobile phone screen glass is being touched (note: not directly in contact with the sensor), the skin will emit a small electric pulse. , trigger the sensor to make it recognize the unlocked phone. When the mobile phone is turned off during non-working hours, the user can push the mobile phone screen through the finger to wake up the ultrasonic fingerprint recognition.

Ultrasonic fingerprint identification technology works in detail

When the user’s electrical signal hits the sensor, it emits a sound wave that is reflected to the user’s skin. The surface of the human skin is not flat, and each person’s fingerprint has a unique “Valley” and “ridge” pattern. The ultrasonic waves are reflected back to the processor, and the processor draws a fingerprint pattern based on the skin acoustic pressure readings. In layman’s terms, different voltage levels are calculated based on the patterns of the fingerprint “Valley” and “ridge”.

For a simple example, suppose the “ridge” is 1 and the “valley” is 0. The Ultrasonic Sensor Module draws this data to create a detailed 3D fingerprint image. Sound waves can also detect human blood, so broken fingers, fake fingers, and artificial skin can’t fool ultrasound fingerprinting.

In recent years, with the rapid development of biometrics in the fields of finance and security, the safety of biometrics has also received much attention. Ultrasonic technology and other fingerprint identification technologies, especially the advantages and disadvantages of optical fingerprinting technology, appear when the security requirements of biometric identification are increased.

Ultrasonic fingerprint and optical and capacitive fingerprint identification technology differences

At present, Chinese manufacturers such as Huawei, vivo and OPPO adopt optical fingerprint identification technology. The technique is to reflect light to the user’s finger and then back to the sensor. The sensor draws the user’s fingerprint information reading into a two-dimensional image, so it is basically the shape “photograph” of the user’s fingerprint “ridge” and “valley”.

Experts have said that the working principle of optical fingerprinting determines that it is easy to be deceived by photos and high fingerprints (such as fake fingerprints drawn by AI). Qualcomm claims that its ultrasonic fingerprint sensor is capable of scanning and reading 4 mm of depth information from the user’s fingerprint to achieve the so-called pore level.

The principle of capacitive fingerprinting is that when the user presses a finger on the back, side or front button of the phone, the fingerprint is captured by the capacitive sensor. On the touch screen of the mobile phone, the finger will emit a small amount of electric charge, so that the mobile phone displays the screen to accurately sense the position of the finger touch. The capacitor measures the charge through the scanner, and then matches the charge pattern with the finger fingerprint information at the time of registration to detect the position of the fingerprint “ridge”.

Samsung gradually abandoned the iris recognition technology?

In the 2017 Apple New Product Release Conference, Apple iPhone X is equipped with face recognition technology, which is the Face ID function. Face ID draws depth information about the contour of the face through 30,000 infrared points. As an Apple competitor, Samsung introduced iris recognition technology (the human eye consists of three parts: the sclera, the iris, and the pupil, and the iris is based on the iris part of the human eye for identity recognition). There are very few manufacturers of iris recognition technology in Chinese mobile phones, and only some small and medium-sized manufacturers use them, such as Gome mobile phones.

Some people believe that Face ID and iris recognition are technically indistinguishable and each has its own advantages. Since the application scenario at the lower end of the line is concentrated in the financial field such as banks, the security of the face recognition technology is very high. Therefore, not only the requirements for face recognition are higher, but the technology also requires a lower error rate. Alibaba Ant Financial combines face recognition and iris recognition to improve recognition accuracy and capture more detailed 3D identity information.

Samsung S9 uses face recognition (RGB technology) + iris recognition, iris recognition is very safe, but RGB face recognition is general, but one advantage is fast, so Samsung wants to combine the two, such as general unlock Face recognition is used, and iris recognition is used when paying, which is fast and safe. However, this system design is still flawed, and someone used a photo + contact lens to fool the system.

This year, Samsung gradually began to abandon the iris biometric technology that has always been proud of its intention to directly compete with Apple’s Face ID function. In the context of face recognition “great”, Samsung’s built-in ultrasonic fingerprinting technology in important flagship models such as the Galaxy S10 is unexpected. The Galaxy Note 10, which will be released in August this year, will probably not use iris recognition technology.

Regardless of the reason, and whether the future face recognition or ultrasonic technology is recognized, as the Qualcomm propaganda said, the ultrasonic fingerprint identification technology is more secure, then the technology will continue in the terminal products for several generations in the future.