Smartphone fingerprint scanners: types and functions

Types and functions of the fingerprint scanner - CONTENTS

1. Development and placement of fingerprint scanners
2. Types of fingerprint scanners
3. What are the advantages of using a fingerprint scanner?
4. COMPARISON: fingerprint scanner vs. face unlock

Development and placement of fingerprint readers

Until recently, the most common type of security was a password or a short PIN code. But no one wants to enter a password sometimes even 50 times a day so people often left their phones unprotected. This triggered a gradual development of fingerprint scanners which are massively used today.

To get a perfect scan of your fingerprint, the scanner must be big enough. You should be able to fit the entire finger pad on the scanner. Apple showed the way already in 2015 with the iconic smartphone iPhone 5S. The round Touch ID sensor was ideally sized and extremely accurate. On the other hand, some Android phones still used the narrow rectangular button as scanner with a very small chance to unlock the phone at first attempt.

The fingerprint reader is normally located either on the back of the phone, on the side button, or at the bottom edge directly below the display. However, this option is slowly disappearing with increasing demand for frameless displays. It is gradually being replaced by scanners built into the display.

The scanner placed on the side unlock button is a great idea, but modern smartphones with a thickness of only about 8.5 mm offer little space for the reader. It very much depends on the process of initial finger scanning. If it's successful, the reader works well and with just one move you light up the display and unlocks the phone. However, there is a relatively high risk that the finger reader won't recognize your finger on first attempt and you might need to try several times, which can be irritating.

You have to get used to the reader located on the back. Manufacturers often place it below the camera lens, which can be a problem with large screen phones. The phone cannot be unlocked if it is lying on a desk or placed in a holder, for example when driving a car. In normal use, a well-positioned scanner on the back is a powerful assistant.

Types of fingerprint readers

There can be huge differences between different types of fingerprint scanners, both in terms of technology and function.

Optical fingerprint scanner

The oldest type of reader that recognizes a fingerprint from a photograph. It captures a 2D picture of the finger. You may know these from older laptops, but this technology has been recently used also for the first scanners built into the display.

Capacitive fingerprint scanners

The most commonly used type of smartphone fingerprint scanners these days. The capacitive fingerprint scanner is made up of hundreds or thousands of capacitors which recognize the papillary lines of the finger thanks to the electric charge. It is basically a 3D map of your finger.

Ultrasonic fingerprint scanner

To obtain a fingerprint scan, the sensor is equipped with both an ultrasonic transmitter and an ultrasonic receiver. The signal is sent to the finger and the receiver gradually evaluates the time sequence of the signal that bounces back to the sensor. So the longer you lay your finger on the sensor, the more detailed your fingerprint will be. It is the latest fingerprint scanning technology.

What are the advantages of using a fingerprint scanner?

Although the type and position of the fingerprint reader are important, the functions of scanner itself offers are even more important:

• Safely and quickly unlocks your phone without entering your PIN or password.
• Easy verification of mobile payments with Google Pay or Apple Pay .
• Unlocks access to selected apps, for example, in parental control mode.
• Gestures - such as showing/hiding the info bar and much more. It always depends on the phone, it is not a feature offered by all phones with a fingerprint scanner.

COMPARISON: fingerprint scanner vs. face unlock

The trend of face unlock feature started with Apple in 2017 when it launched its iPhone X with this new technology easily identified by black cutout at the top of the phone.

Apple has sacrificed the proven technology of unlocking the phone via fingerprint Touch ID without any problems. He replaced it with Face ID, which works on the basis of accurate scanning of the 3D model of the face. The TrueDepth camera projects and analyzes over 30,000 invisible dots, creating a depth map of the face while capturing the face with infrared light. And we have to confirm from our own experience that this is a quick and basically flawless way to unlock the phone.

In contrast, competitors tend to choose the less secure technology of face recognition using an ordinary front camera. No one has come up with an alternative way to sign in, which would be as fast and secure as Face ID. For this reason, we would prefer to use a fingerprint scanner on Android and a long enough PIN or password as a backup.

Fingerprint scanners may not be as attractive as large displays or fast processors, but they are key elements in data security. If you don't want to loose your data, start using your fingerprint reader today.