Actually in our college , the technology that we use to check-out and check-in our library books is nothing but, RFID technology. It has simplified and made the process of borrowing and returning books not only efficient but also has reduced the manual errors that might take place.
• Sometimes manual error such as marking wrong dates/ wrong book id / miscalculation of fine may happen. However automated system is more accurate and precise.
So , this article provides a brief intro to the system, its working principle and its mechanism..
RFID stands for Radio Frequency Identification System . It’s a smart technology based identification system which helps identifying objects with the help of tags attached to them, without requiring any light of sight communication between the tags and the tag reader. The radio waves are responsible for communication and exchange of data between RFID tag and reader.
COMPONENTS OF A RFID SYSTEM:
It consists of a silicon microchip connected with a small antenna and mounted on a substrate. This is then placed on the desired material, in our case -it’s the library book . Thus the book is said to be RFID tagged.
Tags may either be read-only or may have serial number that is used as a key to access their particulars in the database, or may be read/write, where object-specific data can be written into the tag by the system user. Each and every tag has unique serial key for identification.
It consists of a scanner again, with antennas to transmit and receive signals and is responsible for communication with the tag. It helps us to exchange the information from the tag. This setup is placed both while borrowing books and returning books in our library.
PROCESSOR OR A CONTROLLER:
A Microprocessor or a microcontroller that is pre-programmed to perform the operation after getting reader input. It access the database , searches for the particular key based on input and performs the required task.
CLASSIFICATION OF RFID SYSTEMS :
BASED ON HOW THEY ARE POWERED :
• Active RFID system: These are systems where the RFID tag has its own independent power source (like battery,etc.,). They are mostly used for long distance identification. Their only drawback is that their working is dependent on the life of battery.
• Passive RFID system: These are systems where the RFId tag get their power from the reader. The commonly used methods for the same is induction coupling. They are used for short range transmission. They are more cheap ,economical and power conserving.
• A battery-assisted passive (BAP) : It has a small battery on board and is activated when in the presence of an RFID reader.
However , the system employed in our library is Passive RFID system. It is cheap and economical as it has no battery and more suitable for short-range purposes.
The tag reader is responsible for powering the tag and opening the bridge for communication with the tag . The power for the tag can be transferred in many ways. However the most commonly used and economical ones are only two. The first one is magnetic induction method(near field coupling) and second is electromagnetic wave transfer method by using electromagnetic properties (far-field coupling).
WORKING OF PASSIVE RFID SYSTEM :
Most of the passive tags are powered from RFID reader by induction coupling method or by Electromagnetic wave propagation method. Let’s see their working one by one.
INDUCTION COUPLING METHOD:
In this approach the RFID tag gets power from the reader through inductive coupling method. The reader consists of a coil connected to an AC supply. So, as current flows through the coil , magnetic field is induced to form around it. Similarly the tag also has a coil. Whenever the tag coil comes in the vicinity of the reader coil , an electromotive force is induced in it according to Faraday’s law of induction. The EMF causes a flow of current in the coil, thus producing a magnetic field around it. By the virtue of Lenz law, the magnetic field of the tag coil opposes/affects the reader’s magnetic field and this will influence the reader coil. Actually there will be a subsequent increase in current through the reader coil. The reader intercepts this as the load information. This system is suitable for very short distance communication. The AC voltage appearing across the tag coil is converted to DC using rectifier and filter arrangement.
EM wave propagation method (Far Field Coupling):
The dipole antenna present in the reader transmits electromagnetic waves which are received by the dipole antenna present in the tag. The antenna in tag receives this energy in the form of potential difference that appears across the arms of the dipole. Then It is rectified, filtered and linked to the capacitor which stores the energy in order to supply power to the tags. The receiver antenna is varied at different impedance which causes it to reflect a part of the received signal. This reflected signal is received by the reader and information in interpreted.
REAL-TIME WORKING IN LIBRARY :
In our library , each and every book bought is subjected to RFID tag fixation. Tags containing small microchips are affixed on any suitable place on the book. Each and every tag has unique id that is mapped to the name/ISBN of the book . RFID reader transmits an encoded radio signal to identify the tag. When a RFID tagged book is placed on the reader , the information contained on the microchips is read by it. Then according to the programmed algorithms in the microcontroller , the status of book is updated and the corresponding details are printed as a receipt(Now it is sent via e-mail) with due date. Since the tags have individual serial ID’s, the RFID reader can discriminate among several tags that might be within the range of the RFID reader and read them simultaneously.