The most important factor that determines the efficiency of unlocking mobile phone fingerprints is the fingerprint identification chip. The mainstream fingerprint identification chips used by domestic mobile phone manufacturers mainly include: Authentec (acquired by Apple), Synaptics (Samsung is the main customer), Qualcomm (ultrasonic identification), FPC (widely used) and Ding Hui Science and Technology (adopted by Meizu and other manufacturers).
Capacitive fingerprint identification
Principle: Depending on the resistance of human skin cells, the tissue structure of skin can form gullies. When they are squeezed together, changes can be detected, and this change will remain basically unchanged on the same fingerprint, thus obtaining the concave and convex information on the fingerprint.
At present, capacitive fingerprint identification considers sensors, and the materials of fingerprint identification elements are designed according to sensor parameters.
Synaptics announced that it began to provide samples of its brand-new 6x6mm Natural ID FS4500 fingerprint sensor solution, which can provide secure biometric function through glass or ceramic keys (the thickness of the glass cover can be as high as 300 microns). The sensor can realize the function of hidden fingerprint identification, which is similar to Qualcomm ultrasonic fingerprint identification. It is expected that the capacitive fingerprint identification function will be integrated under the thicker glass cover and screen. Ding Hui Science and Technology has also developed IFS fingerprint identification and touch integration technology, which can be directly integrated under the panel without opening holes in the fuselage.
Ultrasonic fingerprint identification
Principle: Ultrasonic waves have the ability to penetrate materials, and produce echoes with different sizes with different materials (when ultrasonic waves reach the surfaces of different materials, they will be absorbed, penetrated and reflected to different degrees). Using the difference of impedance between skin and air to sound waves, we can distinguish the positions of fingerprint ridges and valleys and collect fingerprint information.
Because the ultrasonic wave has certain penetrability, it can still work when there is a little dirt or moisture in the finger, and it can penetrate glass, aluminum, stainless steel, sapphire, plastic and other equipment for identification, and the recognition success rate is higher. At the same time, the sensor can be installed in the equipment and integrated with the equipment, and the fingerprint identification unit does not need to be made into an exposed surface component separately, so that the integrity is stronger.
Xiaomi 5s/plus is the first mobile phone with ultrasonic recognition. With the help of Qualcomm ultrasonic fingerprint identification technology and radio frequency technology, it relies on the signal reflection of specific frequency to detect the specific form of fingerprint. After the test results come out, the recognition accuracy is also very high when the hands are wet, and 5s plus is a little faster than 5s. (The process of fingerprint input is slightly slower than that of capacitor, and it takes about 16 times in 5s and about 8 times in plus).
The fingerprint of 5s is identified below the front, and there is no hole in the whole panel glass, and a groove is made in the identification part (the groove is for practicality, so that users can find the identification part in their pockets and prevent misoperation). The fingerprint recognition of 5s plus is under the double lens of the brushed back cover.
Although iPone7/plus and 1+ have been upgraded to touch capacitance fingerprint recognition, there is still a technical gap with ultrasonic.
Mobile phone fingerprint identification device
Different manufacturers have different ideas about the arrangement of fingerprint identification keys, and each has its own reasons. The emphasis is on personal preference and adaptation.
panel
Apple, Samsung, Meizu, Xiaomi, OPPO, vivo, etc.
Due to the influence of the front layout of the iPhone5s, the preconceived effect makes users and manufacturers more willing to accept the front panel layout scheme, and the front layout in appearance makes the whole machine more integrated.
With the increase of the screen size of the mobile phone, the key position is generally low, so it is easy to hold the mobile phone out of balance when the fingerprint is unlocked, and the mobile phone needs to be readjusted after the unlocking is completed. In addition, the front button will limit the screen ratio, and the fingerprint front is not a good choice for the mobile phone with virtual buttons.
postoperculum
Huawei, letv, HTC, Xiaomi, OPPO, vivo, etc.
Because the keys are relatively free when the back cover is set, the keys can be set according to the finger position of the handheld mobile phone, and the user can unlock the mobile phone while picking it up. The layout of the back cover can make room for the front panel, increase the screen ratio and make the front panel look simpler, but at the same time, it also adds a hole to the back cover.
Sorry about the layout in the back, there is news when the phone is flat, and the fingerprint can only be unlocked by picking up the phone. It would be much more convenient if fingerprints were arranged on the front.
Other unlocking methods
Iris unlocking
The user holds the mobile phone 25-35cm in front of him. After the infrared camera module and the distance sensor confirm that the user's posture is correct, the user's iris is quickly scanned and matched with the biometric data on the mobile phone.
eyeprint discerning
The technical cost of eye pattern recognition is not high, but iris recognition is superior to eye pattern recognition in fault tolerance, information content and stability.
Voiceprint unlocking
With the development of voice application technology, everyone has a unique voice, which can also be used as an unlocking certificate. 20 15, wechat launched the voice lock function. By repeatedly recording the tone and timbre of the PIN code composed of numbers read by the user as a reference, the user does not need to enter a password every time he logs in, but only needs to read a number.
Brush face to unlock
Before turning on the unlock function, users will take photos of faces with different angles or expressions. During the unlocking process, the phone will start the front camera and compare it with the pre-recorded photos to unlock it. Security is not high, you can unlock it with photos.
NFC unlocking
As a mature technology, NFC has been used in access cards, bus cards and bank cards for many years, and the principle is the same. As long as the key of the NFC sticker or card matches the phone, it can be unlocked by "dropping" it on the phone.
Time unlocking
It may be useful for parents to set a time to unlock the mobile phone when it reaches the set time.