At present, the fingerprint readers provided in the market are mainly divided into two categories according to the different fingerprint sensors, namely: optical fingerprint readers represented by Central Control, Ke Mi, Hanwang, Qingsong and Guangzhou Sanxin and Hong Kong Longjie. Capacitive fingerprint reader. The optical sensor is also called the first generation sensor, and its principle is to form a fingerprint image through the principle of optical imaging, and the fingerprint recognition template is formed by analyzing the stripe characteristics of the fingerprint image; the capacitive sensor is also called the second generation sensor, and its principle The fingerprint image is formed by the silicon chip in the sensor under the pressure of the finger, which affects the electrical characteristics (the pressure of the convex part is large, the pressure of the concave part is small), and the fingerprint is formed by recording a specific number of pressure values ​​in a specific area Identify the template.
The following is the basic technical performance comparison of the two fingerprint sensors:
External environmental impact:
Because the optical fingerprint sensor is identified by the principle of optical imaging, the strength of the external light will identify the accuracy. If it is under strong outdoor light, it will be difficult to identify. At the same time, the optical imaging principle has higher requirements on environmental humidity. In too dry environments, such as the north and northwest, the accuracy of use is greatly reduced. On the contrary, the capacitive fingerprint sensor is little affected by the external environment.
The effect of finger surface conditions:
Finger surface conditions include: scratches, peeling, oil stains, dust, sweat, etc. Since the optical imaging is to represent the three-dimensional characteristics of the hand fingerprint path as planar characteristics, any one of the above situations has a greater impact on the recognition accuracy of the optical fingerprint sensor, and sometimes even a decisive influence. On the contrary, the capacitive fingerprint sensor itself senses the three-dimensional characteristics of the finger, and is less affected by the above finger surface conditions.
Fingerprint road conditions affect:
The so-called hand fingerprint path refers to the clarity of the hand fingerprint path, the thickness of the lines, and the degree of slenderness of the finger itself. Through practical application testing and inspection by professional product inspection agencies, it was found that the optical fingerprint sensor is difficult to recognize the slender finger and the finger is too smooth, and the accuracy of recognition decreases. The capacitive fingerprint sensor is very little affected by this. For general optical fingerprint sensors; the false recognition rate of capacitive fingerprint sensors is: <0.0003%, and the rejection rate is: <0.02%.
Product appearance:
Due to the large shape of the optical fingerprint sensor (imaging principle requires a certain focal length), the finished optical fingerprint reader is much larger in shape than the capacitive fingerprint reader, and the optical fingerprint readers currently available on the market The appearance is relatively rough, on the contrary, the appearance of the capacitive fingerprint reader has to be much more beautiful. The fingerprint readers ES-3202 and ES-3205 provided by Yiyuan Intelligent Technology are very small in shape, and the ES-3205 is also an all-metal casing, which is very textured.
Service life:
Because the surface of the optical fingerprint sensor is glass, it is easily broken by the impact of external forces; after a certain number of times, the circuit in the silicon chip will be aged and damaged. In addition, it is not ruled out that it is burned by the strong static electricity of very few fingers. From practice, we found that optical fingerprint sensors have a longer service life, but this is relative.
cost:
Since most fingerprint sensors are imported from abroad, and the cost of capacitive fingerprint sensors is nearly 10 times higher than that of optical fingerprint sensors, the cost of capacitive fingerprint readers is higher than that of optical fingerprint readers. However, the software development package of the optical fingerprint reader needs to be billed separately, and manufacturers generally control each fingerprint reader through the dongle. The capacitive fingerprint reader software development kit is fully developed without any software fee. If the number of one-time purchases is less than 50, the cost of optical fingerprint readers is higher than that of capacitive fingerprint readers, and if large quantities are purchased, the price of capacitive fingerprint readers is higher, but the difference will not be very much. Big. Of course, if the fingerprint sensor is replaced later due to damage, the capacitive one is much more expensive.
Development technical support:
Since the SDK development kit of the optical fingerprint reader implements an authorized sales mechanism, many technical documents are unknown, and few people understand the relevant technical platforms, including the office of Southwest in the southwest of China Control. No one can provide detailed and comprehensive development technology. service. It is very difficult for system developers to apply. The SDK development kits, example programs, and development documents for capacitive fingerprint readers are fully open. In addition, as the southwest technical support service center of Sanxin Company, Yiyuan Intelligent Technology can provide comprehensive development technical services, assist in the development and open a 24-hour technical service hotline, and solve all customer technical problems in a timely manner.
Because of its self forming or tapping the thread matching it, it has high anti loosing ability in combination and can be disassembled. In the small screw, its size, thread type, head type, drilling performance, in the engineering use of high tension, single, unilateral combination features almost unlimited. Self tapping materials can be divided into carbon steel and stainless steel, of which 1022 medium carbon steel is the main material.
1: According to the different head, it can be divided into: round head, flat head (i.e. countersunk head), top stigma, round top wide side head, big round head (i.e. big flat head), hexagon bearing hole head, hexagon bearing hole Huasi head, hexagon bearing hole Huasi head
Round head: it is the most commonly used head shape in the past
Flat head: it can replace the new design of round head and mushroom head. The head is low in diameter, and the peripheral circumference of the head is connected with the high edge of the characteristic, which makes it play a driving role for high-strength torque. It is slightly different from the hole head in head shape
Top column head: the diameter of the standard flat round top column head is smaller than that of the round head, but it is higher due to the groove depth. The smaller diameter increases the pressure acting on a small area, and can be closely combined with the flange and the increased surface layer. As the head is made in the drilling die set to ensure the concentration, they can be successfully applied to the holes in the internal drilling
Dome wide side head: due to the undercutting of the head to restrain and reduce the wear of the wire components, it is most commonly used in electrical appliances and tape recorders, providing an attractive design type for the middle and low head type with its more sufficient bearing surface
Big round head: also known as oval top wide edge head, is a low type, cleverly designed large diameter head. When the combined tolerance of additional function allows, it can be used to cover the metal plate hole with larger diameter. It can also be recommended to use flat head instead
Hexagon socket head: a kind of joint with the height of wrench head and the size of hexagon head. The hexagon is completely cold formed by the reverse hole mold, and there is an obvious depression at the top of the head
Hexagon socket head: such as the standard hexagon socket head, but at the same time, there is a socket face on the base of the head to protect the assembly from damage of the wrench. Sometimes the function of things is far more important than appearance
Hexagon head: This is a standard type of torque acting on the hexagon head. It has the feature of trimming sharp corners close to the tolerance range. It can be recommended for general commercial use. It can also be applied to various standard patterns and various thread diameters. Because of its necessary second process, it is more expensive than general hexagon socket
2: According to the groove type, there are four types: slotted head type (also called slotting), cross slotted head type, cross slotted head type, cross slotted compound slotted head type and meter slotted head type
3: According to the standard can be divided into: GB, DIN, ANSI, BS
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