The library access control system is a control system that guarantees the security of library resources and improves the efficiency and management of library management. Under the support of computer technology, network technology and target recognition technology, there are a large number of library access control systems listed on the market. However, these access control systems are customized according to different library informationization conditions, due to the original books. The structure of the library management system is different, which makes the link between the access control system and other management systems of the library very inconvenient. Moreover, the function of most library access control systems stays at the level of security management and automatic borrowing. In order to realize the seamless link between the access control system and various digital libraries, expand the function of the access control system, and improve the self-service level of the library, we have built a self-service access control system for university libraries based on RFID smart cards.
1 RFID technology and application introduction in the library
1.1 RFID technology
RFID (Radio Frequency Identification) technology is a non-contact automatic identification technology realized by radio frequency communication. The basic principle is to use the RF signal and spatial coupling (inductive or electromagnetic coupling) transmission characteristics to achieve automatic identification of the identified object. As a wireless version of the barcode, RFID technology has the advantages of waterproof, anti-magnetic, high temperature resistance, long service life, large reading distance, data encryption on the smart card, larger storage data capacity, and more convenient storage information. Recognized by the world as one of the ten important technologies of this century. A basic RFID system generally consists of the following parts: a smart card carrying information about the target, ie an RFID smart card, an antenna transmitting RF signals between the reader and the RFID unit, and an RF receiving the return from the RFID smart card. The signal is transmitted to the host system for processing the decoded RFID reader. At present, RFID systems have been used in traffic management, warehousing management, logistics management, and production line tracking.
1.2 Introduction to the application of RFID technology in libraries
RFID technology has attracted the attention of the domestic and international library circles because of its unique characteristics. The National Library of Singapore began using RFID technology in late 1998, becoming the world's first library to apply this technology. Subsequently, the United States, Australia, China, etc. have also adopted this technology. In 2006, China's first RFID intelligent library, the Jimei College Library of Jimei University, was built and put into use. At present, many libraries such as the Shenzhen Library New Library, the National Library, and the Shanghai Changning District Library have also cited this technology. In combination with the above-mentioned libraries using RFID technology, the functions implemented by the library generally include:
â— Self-service borrowing and returning book system: Provide readers with self-service borrowing and returning books, without the intervention of library management personnel;
â—Book sorting: realize automatic counting, arranging, and arranging of the collection materials, so as to achieve the purpose of borrowing and repaying;
â— RFID security detection: For books that have not been processed for lending or forbidden to be loaned, the security device will alarm when going out, reminding management personnel to stop it in time.
Through RFID technology, the library has created enormous social benefits for the library industry in terms of effectively improving management accuracy, improving service image, and expanding extension services, and has been recognized by the majority of colleagues.
2 RFID smart card
A smart card, also known as an integrated circuit card, is an IC card. It is an integrated circuit chip embedded in a plastic substrate and packaged in the form of a card. In 1977, Motorola worked with one of its computer customers to develop the world's first smart card. Since then, smart cards have been popular with their thin and small size, advanced integrated circuit chip technology, and their ability to be deciphered and counterfeited. And has achieved unprecedented development in the world. At present, various smart cards are increasingly being used in various fields of the national economy and reaching into the daily lives of residents.
The RFID smart card is a contactless IC card. With small size, large capacity, long life and reusability, it can support fast reading and writing, non-visual recognition, mobile recognition, multi-target recognition, positioning and long-term tracking management.
2.1 The basic structure of the smart card
The RFID smart card is mainly composed of an antenna, a radio frequency interface, and a micro control unit. The modules included in each component and their functions are as follows:
Antenna: used to receive the signal sent by the RFID reader and return the data information to the RFID reader.
RF interface circuit: mainly includes waveform converter, modulator/demodulator, rectifier, voltage regulator, oscillator, etc. The waveform converter receives the radio modulation signal on the reader, and sends the modulation/demodulation module on the one hand, and performs waveform conversion on the other hand, converts the sine wave into a square wave, and then rectifies and filters the voltage, and the voltage is adjusted by the voltage adjustment module. Further processing, such as voltage regulation, etc., ultimately outputs the various working circuits on the card. The oscillator generates a high frequency signal for modulation/demodulation and a clock signal of the micro control unit.
Micro control unit: implements the identification of the smart card and executes the instructions of the reader. It includes a logic control unit, a request response unit, an anti-collision unit, a data encryption unit, a storage unit (including E2PROM and ROM), and the like.
Request response unit: When an RFID smart card is within the working range of the reader antenna, after the reader sends a command to the RFID smart card, the request response unit will be activated, and the card number of the smart card is transmitted to the reader to establish a smart card. Communicate with the first step of the reader. Otherwise, the reader will not perform other read and write operations on the smart card.
Anti-collision unit: When multiple RFID smart cards enter the operating range of the reader, the anti-collision unit will select one of them to operate. If it is not selected, it will be in idle mode and wait for the next card selection. The process will return to the selected card. Serial number.
Logic control unit: used to decode the signal sent by the RFID reader and send back data to the RFID reader as required.
Data encryption unit: completes the encryption processing and password protection of the data.
Storage unit: It includes E2PROM and ROM, which is mainly used to store data. The data to be stored by the user (personal information of the reader, such as name, profession, hobbies, borrowing and returning records, etc., can also store personal accounts) is stored in the unit. The data in the E2PROM will remain after the smart card loses power and the smart card leaves the valid working range of the reader antenna.
2.2 The principle of reading and writing smart cards
The principle of reading and writing of smart cards is: RFID readers transmit a set of electromagnetic waves of fixed frequency to the RFID smart card. Under the excitation of electromagnetic waves, the LC resonant circuit in the RFID smart card generates resonance, so that the capacitor has a charge inside the capacitor. At the other end, a single-pass electronic pump is connected to store the charge in the capacitor to another capacitor. When the accumulated charge reaches 2V, the capacitor can be used as a power source to supply operating voltage to other circuits. The data is transmitted or received by the RFID reader.
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