RFID (radio frequency identification) is an automatic wireless identification and data acquisition technology, which has been widely used in many fields. This paper introduces the performance characteristics of mainstream RFID technology, and analyzes the application trend and technical development trend of this technology in the future.
RFID is an automatic wireless identification and data acquisition technology, which has been used for many years and has more and more application fields. Today, smart chips with readable and writable memory that can prevent unauthorized access can be seen in many containers, pallets, product packaging, smart ID cards, books or DVDs. Due to possible applications in the future, RFID is about to usher in a very huge growth period. The global market of this technology, chip, card reader, software and business will grow from US $1 billion in 2002 to US $2.6 billion in 2007.
The application will continue to focus on the field of supply logistics. In this field, RFID transceivers are used to record and track all kinds of movable goods / products. The necessary storage on RFID transceivers (plastic / paper roll labels in the size of credit cards, including chips, RF parts and antennas) will continue to be the main application. Another possible application is to attach the transceiver label to textiles, drug packaging or even a single drug box. However, in the future, RFID will also be used in areas such as local public transport, car remote keys, transmitting tire pressure and mobile phones. Rapid identification is important for the company's logistics procedures, large warehouses, clinics or the transportation of goods, as well as in business. For example: Car tables and chairs must enter the assembly line according to color ordered at the right time; The smart RFID tag will automatically detect the correct drug container from storage to production; The blood sample will accurately correspond to the patient who collected the blood sample; The supply of fresh goods required by supermarkets requires a very complex sending network, which is not allowed to make mistakes; There will be no fake tickets for the 2006 World Cup, thanks to RFID chips.
Another focus of the future will be in the automotive industry, such as controlling rearview mirrors, all motors and car door lighting. Looking further ahead, e-ticketing, "e-passport" and even special communication services have revealed the opportunity of rfid-ic application. Bundesbank Bank of Germany expects RFID to be applied in banknotes. Unlike today's banknotes, such banknotes cannot be simply forged with color printers or copiers, but in fact, chip manufacturers need to be able to produce rfid-ic as thin as paper and as big as sand.
The best RFID Technology: meet the application
Many facts have proved that the main sales opportunities exist in the logistics process. Different technologies can be adopted according to the industry and performance requirements (such as reading speed and the number of RFID tags that need to be read at the same time). RFID technology can be basically divided into low-frequency system, high-frequency (HF) system with frequency of 13.56MHz, ultra-high frequency system (UHF) with frequency band of about 900MHz, and system working in microwave frequency band of 2.4GHz or 5.8GHz (see table). In addition to the frequency range, another difference factor is the power supply: passive RFID transceivers, which are mainly used in logistics and target tracking. They have no power supply, but obtain energy from the RF electric field of the reader / writer; The active transceiver is battery powered, so it has a long distance of tens of meters, but it is larger and, most importantly, more expensive.
Important parameters of RFID Technology
Low frequency RFID chip (passive) works at a frequency of about 130KHz. At present, it is mainly used in access control, animal ID, electronic lock frame, authorization inspection of machine control, etc. The very slow reading speed of this technology is not a problem, because only very short information needs to be transmitted in one direction, and the corresponding ISO standards are 11484 / 85 and 14223. 13.56MHz system will become more and more important in many industrial fields. This system is classified as passive and has the characteristics of high miniaturization, which has been continuously improved in recent years. The system used to obtain goods and product information and comply with ISO standards 14443 and 18000-3,1 is relatively slow. In some cases, one reading operation takes several seconds, and the specific time required for different data amounts is different. According to different types, the ISO 15693 standard type system can deal with moving targets with a maximum speed of 0.5m/s, obtain a data transmission speed of up to 26.48kbps, and realize the recognition of 30 objects per second.
However, in the future large-scale logistics applications, the traditional methods working at 13.56MHz and even the recent methods defined in ISO 15693 can no longer meet the needs. In this application, phase jitter modulation (PJM) technology appears. PJM's RFID volume label is suitable for tagged objects to pass through the reader at high speed anywhere on the conveyor belt, and must be read one by one at a very high data rate, such as identifying tightly packed drugs, airport baggage tracking or logging in documents at a distance of up to 1.2 meters.
Table: comparison of main RFID technologies.
Continuous switching between eight RF channels increases the speed of reading and ensures reliable identification, even under large throughput. Based on Magellan's PJM technology, Infineon and Magellan technology in Australia have cooperated to develop chips for this purpose. Compared with the current 13.56MHz RFID technology, these chips can provide 25 times faster reading and writing speed and 848kbps data rate. PJM system is optimized for logistics (ISO standard 18000-3 mode 2), which can reliably identify, read and write up to 500 electronic volume labels in less than one second. Even when the target moving speed is 4 meters / second, the RFID reader for these new chips are competent.
10KB of available memory is equivalent to about two DIN A4 pages of simple text storage. This memory space can be further divided into several sectors, and only authorized people can read and write access. Special encryption methods prevent unauthorized access to stored data.
UHF and microwave systems can eventually allow a coverage distance of several meters; They usually have their own batteries, so they are suitable for the identification of large goods in the pallet on the loading ramp, for example, or even the vehicle chassis on the product line of the automobile factory. The disadvantages of these frequency ranges are the negative effects of atmospheric humidity and the need to maintain the orientation of the transceiver relative to the read-write antenna from time to time or at all times.
Application leading technology
Usually, a particular application dominates which technology to adopt. For department stores, it is of course meaningless to label goods just to facilitate reading at the sales terminal, because in the current cost environment, this will make products more expensive. However, the following applications are very meaningful: when lending books or CDs in the library, the 13.56MHz label pasted on books or CDs can read the label in a few seconds, or reliably identify drugs on the selection conveyor belt of drug wholesalers, so as to avoid misdistribution of drugs that may cause serious consequences.
However, basically, the task of reading, identifying and tracking any object can benefit from the thoughtful application of RFID technology, especially when every data must be written to the chip, modified by authorized users and preventing unauthorized access to segmentable memory - if possible, even at very high speed and a large number of objects can be processed at the same time.
Will bar codes be phased out?
This question may be based on the facts mentioned above, but the answer is No. Because of the cost, the 0.25 Euro cheese cans sold in supermarkets will continue to use bar codes for a long time. However, it is absolutely conceivable that in the next three to five years, the current occasions for using bar codes will be open to RFID tags, such as identifying large items such as textiles or parcels, and the payment of urban public transport or vending machines. In all these applications, RFID working at 13.56MHz has advantages over bar code in terms of reliability, pollution avoidance, visibility, reading speed and spatial directivity, not to mention the problems caused by contact. In theory, RFID can read and write indefinitely.
RFID tag costs are falling
The cost of RFID technology is related to its practical application. According to the size of the antenna attached to the metal substrate (currently 7.5cm for 13.56MHz) × 4.5cm or 4.5cm × 4.5 for the ring antenna diameter of CD (5cm), when the amount reaches 1 million, the cost of embedding RFID (i.e. chip, connection to antenna and antenna on base material) is about 50 points. In the next two to three years, this will change: the price will reach 20 points as soon as 2006 or 2007. About 50% of the cost is the chip cost, and the other half is the cost of antenna and substrate materials (metal sheet and paper, or adhesive layer). Of course, the cost is related to the size of the antenna and the quality of metal sheet or paper. For example, holographic paper will inevitably make RFID tags more expensive.
Technology behind RFID
RFID (radio frequency identification) system consists of two parts: read / write unit and electronic transceiver. The reader sends electromagnetic pulses through the antenna, and the transceiver receives these pulses and sends the stored information to the reader as a response. In fact, this is the non-contact reading, writing or deletion of data in memory. Technically speaking, the "smart tag" includes an RFID circuit including an RFID chip with an RFID RF part and an ultra-thin antenna loop, which is embedded in the tag together with a plastic sheet. Usually, a paper label is also pasted on this label, and some important information can be clearly printed on the paper label. Currently, smart tags are generally the size of credit cards, and there are 4.5 for small goods × 4.5cm size labels, as well as 4.7cm diameter circular labels used on CDs and DVDs. Compared with other ID technologies such as bar code or magnetic stripe, the advantage of transceiver technology lies in the wireless link between reader and transceiver: the read / write unit does not need visual contact with the transceiver, so it can be fully integrated into the product. This means that the transceiver is suitable for harsh environments and is not sensitive to moisture, dirt and mechanical effects. Therefore, the transceiver system has very high reading reliability and fast data acquisition. The last and important point is to save labor and paper.
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