Fingerprints glass door locks, due to their lifelong immutability, uniqueness, and convenience, have almost become synonymous with biometric identification. Fingerprints refer to the uneven lines on the skin on the front of a human finger. The lines are arranged regularly to form different patterns. The starting point, ending point, joining point, and bifurcation point of the ridge is called the minutiae feature points of the fingerprint.
The points formed by the interruption, bifurcation, or turning of the fingerprint reader are the minutiae feature points, and these minutiae feature points provide the confirmation information of the uniqueness of the fingerprint. The fingerprint recognition sensor records the direction of the fingerprint pattern and digitizes it to form a unique key to unlock your mobile phone.
From the principle point of view, frameless glass door locks, fingerprint recognition does not seem to be advanced, and with the advancement of technology, the sensitivity of fingerprint recognition of mobile phones has become higher and higher, but when people are immersed in the safe and convenient experience of fingerprint recognition Many people have discovered a flaw in fingerprint recognition, that is, after being dipped in water, many of the fingerprint sensors of mobile phones that are very sensitive in normal use become less sensitive, so why? Today we will analyze the reasons for you.
Speaking of the reasons, we must first determine the method of mobile phone fingerprints. At present, there are mainly three types of fingerprint collection: in vivo optical, capacitive, and pressure-sensitive, and the higher utilization rate in mobile phones is mainly capacitive. When it comes to capacitance, everyone should be able to think of capacitive screens. They have the same principle, and they all use the current induction of the human body to work.
The periphery of the fingerprint recognition sensor is plated with long and narrow electrodes. When the user's finger touches, due to the human body's electric field, the user's fingerprint lines and the sensor surface will form a coupling capacitor. For high-frequency current, the capacitor is a direct conductor, so the finger will A small current is drawn from the contact point. This current flows out from the peripheral electrodes, and the current flowing through the peripheral electrodes is proportional to the distance from the fingerprint to the periphery. The controller calculates the current ratio accurately to obtain the touch pattern. It should be roughly like this, involving detailed details. The calculation editor is not very familiar.
To put it simply, where the user's fingerprint is, wherever there is "leakage", the sensor will respond. When the sensor is wetted with water or the hands are sweaty, because of the conductive properties of water, when the water touches the sensor and touches the sensor again, the current will be affected, so the above calculation is inaccurate.
For the method, I believe that many friends have their own solutions. Wiping the fingerprint recognition sensor with paper and drying the hands should be a better way. Of course, because the fingerprint recognition sensor may also keep the humidity around, sometimes even after we wipe it, Inaccurate recognition will still occur, so the best solution is to temporarily unlock with a password or pattern, and then perform recognition after the sensor is completely dry.
Author: Written by Ms ZhangZiJuan from S4A INDUSTRIAL CO.,LIMITED
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