Basic elements of mechanical lock access control system or access control system
The access control system is a very common device used in security systems. Its technical content includes automatic control, detection, television, sound, feature recognition and linkages of various types of locks, security doors, locking devices, etc. It can be said that the access control system covers all the elements of the security system. It is an indispensable part of a large integrated security system and can also be used to form a variety of practical security systems. It is precisely because of the diversity of application of access control technology, the perfect function and wide adaptability that it has become the focus of research and development of security technology, and various high-tech technologies are continuously applied to access control systems. However, when we analyze the access control system, we still start with "mechanical locks." The reason for this is that an independent mechanical lock seems to be very different from a complex access control system, but in essence has the same basic elements. The mechanical lock is the simplest and most complete access control system. From the analysis of it, many basic concepts and evaluation methods of the access control system can be obtained. The access control system is an application method of access control technology in the real world.
The feature carrier, feature reading (recognition) device and locking mechanism are the three basic elements that make up the access control system.
1. Locking mechanism, access control system only has the practicality of adding appropriate locking mechanism. When the reading device confirms the identity and authority of the holder, it is necessary for the legal person to smoothly enter and exit, and effectively block the request of the illegal person.
The mechanism lock is a locking mechanism of the access control system. When the lock core and the key shape of the key are matched, the handle can be rotated to retract the lock tongue to open the door. Different types of locking mechanisms constitute different access control systems, or different applications that implement access control technology. For example, the lever of the subway toll collection system, the car stop for the parking lot, and the cash withdrawal device for the self-service bank. Locking If the mechanism is a door, the system controls the opening and closing of the door, which is the "access control" system.
2. Feature carrier, access control system is a system for managing and controlling people flow, logistics and information flow.
There are many feature carriers that can be utilized in the access control system, such as magnetic cards, optical cards, and IC cards that are currently the most commonly used. These feature carriers are to be used with the holder (person or thing), but it is identical to the holder, which means that the feature carrier can be held by someone else. In order to prevent this problem, multiple methods can be employed, that is, two or more feature carriers are used (depending on the security requirements of the system). If you can choose a unique and stable feature from the holder itself, as a means of expressing identity, this problem does not exist. First, the system should be able to confirm their identity and determine the legitimacy of their entry and exit. This is to give them a sign of identity and authority through a method, which we call the feature carrier, and the information about the identity and permissions it contains is the feature. The key to a mechanical lock is a feature carrier whose "tooth shape" is a feature. The feature from the "holder" is called "biometric", and the feature carrier is naturally the holder.
3. A reading device is a device that exchanges information with a feature carrier. It reads information about identity and permissions from the feature carrier in an appropriate manner to identify the identity of the holder and the legitimacy of its behavior (incoming and outgoing requests).
The feature reading device has only the function of reading information, and some has the function of writing information to the feature carrier. Such a device is called a "read-write device", and writing information to the feature carrier is authorized by the system to the holder. Or modify the process of authorization. This feature carrier is modifiable and reusable. The key to the mechanical lock is generally not modifiable, and the authority it represents cannot be changed. Human biometrics cannot be modified, but the permissions they have can be changed through system settings. The feature reading device is a device that matches the feature carrier, the technical properties of the carrier are different, and the properties of the reading device are also different. The reading device of the magnetic card is a magnetoelectric conversion device, the reading device of the photoelectric card is a photoelectric conversion device, and the reading device of the IC card is an electronic data communication device. The reading device of the mechanical lock is the "cylinder". When the key is inserted into the lock cylinder, the identity and authority of the holder are confirmed by the movable marble in the lock cylinder and the tooth shape of the key. The identification process of the electronic reading device is: converting the read feature information into electronic data, and then comparing with the data stored in the device memory to realize identity confirmation and authority authentication, which is also called “feature recognition”. ".
Above, we analyze the basic elements of the access control system or the access control system through the analysis of the mechanical lock. Below we will start from the mechanical lock and explain the main technical indicators of the evaluation of the access control system:
The larger the key amount of the system, the larger the capacity of the system, and the higher the security, because the possibility of being deciphered or the possibility of being copied is smaller. If each tooth is regarded as a feature (T) and the high and low order of the tooth is regarded as the difference (S) that each feature can express, the key amount of the system is TS. Information cards can have a large amount of keys (by setting), and human biometrics have a very large amount of keys. It is therefore the best choice for high security requirements for access control (access control) systems. The amount of key, a key, its number of teeth, and the order of the height of each tooth determine the number of tooth forms that can be formed. This is the amount of keys. For example, the key consists of 5 teeth, each tooth has 5 steps (step difference) mechanical lock, its key amount is 55, the key amount of the information card is determined by the length of the data indicating its characteristics. If the feature is represented by an 8-bit binary number, its key amount is 28.
The rate of misunderstanding and the rate of false rejection often encounter situations where the lock is opened by another key and the key is not easy to use. The same is true for an old lock. This is the misrecognition rate and the false rejection rate. concept. The error in the information communication (reading) of the system is the cause of the above-mentioned mistakes, and the problem is more likely to occur when the key amount is low.
Security, system security includes two aspects,
(1) The above mentioned ability to prevent being deciphered and copied,
(1) The ability to resist mechanical damage, the system's locks have a great relationship. The state has set standards for this, and the standard mechanical locks are called anti-theft locks.
The friendliness of the system, the access control system has two interactive interfaces with people.
(1) an interface for character information interaction,
(1) The door opening/locking process, the door system should be friendly to people, including the reading characteristics are not compulsive, and the access process is smooth and safe.
In addition to the mechanical lock, the locking mechanism of the access control system is also commonly used as an electronically controlled lock. Its characteristic carrier is mainly various information cards, and the opening and closing of the door is controlled by electromagnetic force. The safety of the access control system includes the impact strength, that is, the resistance to mechanical damage, which is mainly determined by the locking mechanism of the system. Some biometric and electronically controlled access systems have this friendliness and are widely used.