Smart lock, the earliest more people are willing to call fingerprint lock. Therefore, it is not difficult to see that among the many unlocking functions of the smart lock, the demand for fingerprint unlocking is the highest. After all, fingerprints are the only biological key that will follow you at any time in your life, which is really very convenient. There are generally two types of smart lock solutions to fingerprint identification: optical identification and semiconductor identification. Let’s talk one by one
1. Optical recognition
Optical recognition is a relatively “old” fingerprint recognition technology. The principle is to use the reflection of light. After the light is reflected, the shape of the fingerprint is formed on the CCD and then the algorithm is recognized. Therefore, the fingerprint recognition area of ​​the optically recognized smart lock will emit light when it is working.

The advantages of optical recognition are that the technology is mature and stable, the components have a long service life, and the production cost is lower than that of semiconductor recognition components. Many companies use fingerprint attendance machines with optical identification fingerprint heads.
Of course, the shortcomings of optical recognition are also obvious. Because the principle of light reflection is used to collect fingerprints, the recognition rate of fake fingerprints is low. If someone can get your fingerprint, it happens that your home is an optically recognized fingerprint lock product, then the probability of being opened by a fake fingerprint is higher than that of a semiconductor-recognized product.
Currently on the market, the proportion of optical identification smart locks is getting smaller and smaller, and more of them are semiconductor identification.
2. Semiconductor identification
The principle of semiconductor recognition is much more complicated than optical recognition. To put it simply, the fingerprint panel and your fingerprint form the two poles of the capacitor. After the fingerprint touches the identification panel, the capacitance/inductance value formed at different positions will be different because the fingerprint has bumps. The chip of the smart lock is to “draw” and identify the fingerprint based on the difference in data.
Therefore, the fingerprint identification area of ​​the semiconductor identification fingerprint lock is not illuminated. This is also the most intuitive way to distinguish between optical and semiconductor recognition of smart locks. By the way, Apple X’s previous mobile phones used semiconductor recognition. The biggest advantage of semiconductor recognition is that the fingerprint collection accuracy and recognition speed are higher and faster than optical recognition. And because the principle of capacitance/inductance is used, the fingerprint head of semiconductor recognition can penetrate the skin layer, which is the so-called “living body recognition.” Therefore, simple fingerprint copying cannot unlock this type of smart lock. And because of this feature, even if your fingers are dirty, you can unlock this type of door lock, which is much more convenient than an optically recognized smart lock.

Of course, for users who are worried about their fingerprints being copied and used, what I want to say is that watching too many TV series is not good. If you want to copy fingerprints, you really can’t do it with a handful of flour + a sheet of transparent glue.
In fact, I have thought about trying various ways of copying fingerprints before, but in actual operation, I found that many materials are not available through ordinary channels, after all, they are very sensitive things. So, unless your house is really worthy of a thief to a certain extent, even semiconductors are not a perfect solution. But having said that, since they are already trenched to a certain extent, the security of the family can’t always count on a smart lock.
In addition, the rejection rate and false recognition rate of the fingerprint recognition module are also briefly described. Of these two, the former is related to the user experience, after all, sometimes fingerprints cannot be recognized and it is annoying. The latter is about safety. Regarding the false rejection rate and the false recognition rate, the general smart lock business will not write it out specifically. But from my actual experience, the rejection rate of qualified products of regular brands is generally very low, especially for semiconductor recognition. When fingerprints are recorded, the same fingerprint is usually collected 6-8 times. Use a standard. As for the false recognition rate, on the whole, semiconductors are higher than optical recognition.
Therefore, when purchasing a smart lock, it is best to choose a fingerprint lock with semiconductor recognition for fingerprint recognition. On the one hand, I think non-luminous is more advanced, and on the other hand, it is indeed much safer than optical recognition.

advantage:
1. At the same price, the speed of optical fingerprint recognition will be faster than semiconductor fingerprint recognition;
2. Because it is made of glass, the optical fingerprint recognition head will be more durable and wear-resistant;
3. And the price of optical fingerprint recognition head is generally lower.
shortcoming:
1. Although the recognition speed is fast, but the accuracy is not enough, sometimes the recognition fails several times in a row;
2. If the user is stained with water, oil and other stains when identifying the fingerprint, it will not be recognized at all;
3. What’s more deadly is that optical recognition only recognizes the lines of fingerprints, which basically loses the ability to prevent fake fingerprints from unlocking;
4. Since the principle of optical identification is to read fingerprint information with strong light from the fingerprint hair, optical identification consumes more power.
advantage:
1. The recognition accuracy is high, and some fingerprint locks are equipped with self-learning chips, constantly improving the user’s fingerprint information, and the recognition speed will become faster and faster;
2. When recognizing fingerprints, not only the lines of the fingerprints are recognized, but also the fingerprint temperature and micro current are also taken into consideration. Only when the three are completely consistent, the recognition will be successful, and false fingerprint unlocking is completely eliminated;
3. Low power consumption, battery life will increase.
shortcoming:
Semiconductor fingerprint heads are more expensive and not very sturdy. If you accidentally touch a hard object, it will be damaged.

Capacitive vs optical fingerprint sensor

Capacitive fingerprint sensor

Optical fingerprint sensor vs ultrasonic

Ultrasonic fingerprint sensor