In order to improve the efficiency of computer recognition, enhance its flexibility and accuracy, and enable people to get rid of complex statistical recognition work, traditional barcode, two-dimensional barcode, and wireless radio frequency identification technologies have successively emerged. Although they each have their own advantages, both technologies are aimed at obtaining various information about items in a timely manner and processing them quickly and accurately.

Traditional barcode (also known as one-dimensional barcode) technology is relatively mature and can be seen everywhere in social life, and has been widely used around the world. As a means of computer data collection, it has quickly entered various fields such as commodity circulation, automatic control, and file management with many advantages such as speed, accuracy, and low cost. It is also currently the most widely used barcode in China. However, due to the one-dimensional nature of traditional barcodes, they do not carry any information in the vertical direction, have low information density, and cannot display Chinese characters. They are easily rejected due to wear or wrinkles, which greatly limits the application range of traditional barcodes.

1. Narrow one-dimensional space

Traditional barcodes consist of a set of bars and empty symbols arranged according to a certain encoding rule, representing certain character, number, and symbol information. The barcode system is an automatic recognition system composed of barcode symbol design, barcode production, and scanning reading, and is currently the most widely used automatic recognition technology.

So far, there are about twenty common barcode coding systems, among which the widely used coding systems include EAN code, Code39 code, Cross25 code, UPC code, 128 code, Code93 code, and CODABAR code. Different code systems have different characteristics and are suitable for specific application fields. Below are some typical code systems:

1) UPC code (Unified Product Barcode)

UPC code was introduced by the American Supermarket Union in 1973 and is the world's first commercial barcode system, mainly used in the United States and Canada. UPC codes include two systems, UPC-A and UPC-E. UPC only provides numerical codes with limited digits (12 and 7), requires code checking, and allows for bidirectional scanning. It is mainly used in supermarkets and department stores.

2) EAN code (European product barcode)

In 1977, 12 industrialized countries in Europe signed a preliminary agreement in Belgium to establish the International Bar Code Association, which developed EAN codes compatible with UPC codes. The EAN code is only a numerical number, usually 13 digits, allowing for bidirectional scanning and shortening the code to 8 digits. It is also mainly used in supermarkets and department stores.

3) ITF 25 code (cross 25 code)

The barcode length of ITF 25 code is not limited, but its numerical data must be even digits, allowing for bidirectional scanning. The ITF25 code is widely used in logistics management, mainly for packaging, transportation, ticket sequence numbering in international aviation systems, as well as in the automotive and retail industries.

4) Code39 code

Among the 9 code elements in Code39, there must be 3 code elements with thick lines, so Code39 code is also known as the "39 code". In addition to the numbers 0-9, Code39 also provides English letters A-Z and special symbols. It allows bidirectional scanning and supports 44 sets of barcodes. It is mainly used in industrial products, commercial materials, libraries, and other places.

5) CODABAR code (Kudaba code)

This code system can support numbers, special symbols, and 4 English letters. Due to the barcode's own detection function, there is no need to check the code. Mainly used in factory inventory management, blood bank management, library book borrowing, and photo processing industry.

6) ISBN code (International Standard Book Number)

ISBN is an internationally unified coding system that emerged due to the needs of book publishing and management, as well as the convenience of international publication exchange and statistics. Each ISBN code consists of a set of ten digits with the "ISBN" code, used to identify the country, region, publishing institution, title, version, and binding method of the publication. This set of numbers can also be considered as representative numbers for books, mostly used in publishing house book management systems.

7) Code128 code

Code128 code is currently a custom code system within Chinese enterprises, which can determine the length and information of the barcode according to needs. This encoding contains information that can be numbers or letters, and is mainly used in industrial production lines, library management, and other fields.

8) Code93 code

This coding system is similar to Code39, but it has a higher density and can replace Code39.

The enormous changes that barcode technology has brought to people's work and life are evident to all. However, due to the relatively small information capacity of one-dimensional barcodes, such as barcodes on products that can only accommodate a few or dozens of Arabic numerals or letters, one-dimensional barcodes can only identify one type of product and do not contain descriptions of related products. Only with the assistance of databases can people obtain descriptions of related products through barcodes. In other words, without the pre established database, the information contained in one-dimensional barcodes will be greatly reduced. Due to this reason, the use of one-dimensional barcodes is quite limited in places without database support or inconvenient networking.

On the other hand, one-dimensional barcodes cannot represent Chinese characters or image information. Therefore, in some situations where Chinese characters and images need to be applied, one-dimensional barcodes become very inconvenient. Moreover, even if we establish corresponding databases to store the Chinese characters and image information of related products, this large amount of information still requires a long barcode for identification. And this long barcode will occupy a large printing area, which brings difficult problems to printing and packaging. Therefore, people hope that the barcode directly contains various product related information, without the need to query these information again from the database based on the barcode.

Based on the above reasons, practical applications require a new coding system that not only has the advantages of one-dimensional barcodes, but also has the advantages of large information capacity, high reliability, and strong confidentiality and anti-counterfeiting.

In the 1970s, two-dimensional barcode technology emerged in the field of computer automatic recognition. This is an encoding technology developed on the basis of traditional barcodes, which expands the information space of barcodes from linear one-dimensional to planar two-dimensional. It has many advantages such as large information capacity, low cost, high accuracy, flexible encoding method, and strong confidentiality. Therefore, since 1990, two-dimensional barcode technology has been widely used around the world. After several years of effort, it has now been applied in fields such as national defense, public safety, transportation, healthcare, industry, commerce, finance, customs, and government management.

2. The leap from "line" to "surface"　　

2D barcode vs traditional barcode

Unlike one-dimensional barcodes, which can only read data from one direction, two-dimensional barcodes can obtain information from both horizontal and vertical directions. Therefore, they contain much more information than one-dimensional barcodes and also have self correcting functions. But the working principle of two-dimensional barcodes is similar to that of one-dimensional barcodes. When recognizing, printing the two-dimensional barcode on a paper tape and reading the information contained in the barcode symbol requires a scanning device and a decoding device, collectively known as a reader. The function of the reader is to convert spatial signals such as barcode width and spacing into different output signals, and convert these signals into binary codes that can be recognized by the computer and input into the computer. A scanner, also known as a photoelectric reader, is equipped with a light source and photoelectric detection device to illuminate the barcode being read, and can receive the reflected light of the barcode. When the light emitted by the scanner shines on the paper tape, each photovoltaic cell outputs different patterns based on the presence or absence of the barcode on the paper tape. The patterns from each photovoltaic cell are combined to produce a high-density information pattern, which is amplified, quantified, and sent to the decoder for processing. The decoder stores a database of barcode encoding schemes and decoding algorithms that need to be read. In early recognition devices, scanners and decoders were separate, while most current devices have been integrated.

Two dimensional barcodes have the following characteristics:

Large storage capacity. A two-dimensional barcode can store 1100 characters, which is a significant increase compared to the 15 characters of a one-dimensional barcode. It can also store Chinese characters, and its data can be applied not only to English, numbers, Chinese characters, symbols, etc., but also to blank spaces. Moreover, the size can be freely selected, which is something that one-dimensional barcodes cannot achieve.

Strong resistance to damage. The two-dimensional barcode adopts fault correction technology and can be restored even after being contaminated or damaged. Even if the barcode is damaged by up to 50%, the original data can still be interpreted with a misreading rate of one in 61 million.

High security. The use of encryption technology in two-dimensional barcodes greatly improves security.

Can be faxed and photocopied. Two dimensional barcodes can still be used after fax and photocopying, while one-dimensional barcodes cannot be recognized by machines after fax and photocopying.

Printing diversity. For two-dimensional barcodes, they can not only print black text on white paper, but also perform color printing, and the printing machine and printing object are not restricted, making printing very convenient.

Strong anti-interference ability. Compared with magnetic cards and IC cards, two-dimensional barcodes have strong anti magnetic and anti-static capabilities due to their own characteristics.

The code system is more diverse

Two dimensional barcodes can be directly printed on scanned items or printed on labels, which can be specially printed by suppliers or printed on-site. All barcodes have some similar components, they all have a blank area called the quiet zone, located outside the edges of the starting and ending parts of the barcode. Verification symbols are also necessary in some code systems, as they can be used mathematically to verify barcodes to ensure that the decoded information is correct and error free. Like one-dimensional barcodes, two-dimensional barcodes also have many different encoding methods. According to these encoding principles, two-dimensional barcodes can be classified into the following three types:

One is a linear stacked QR code. On the basis of one-dimensional barcode, reduce the height of barcode lines, arrange a narrow and long bar code line with large aspect ratio, stack each line on the top, and separate each line with a module wide thick black bar. Typical linear stacked QR codes include Code 16K, Code 49, PDF417, etc.

Next is the matrix QR code. It uses a unified combination of black and white blocks, rather than a combination of bars and spaces of different widths. It can provide higher information density and store more information. At the same time, matrix barcodes have higher automatic error correction capabilities than stacked barcodes, making them more suitable for situations where barcodes are easily damaged. Matrix symbols do not have modules that indicate the start and end, but they have some special "locators" that contain information such as the size and orientation of the symbol. Matrix two-dimensional barcodes and new stacked two-dimensional barcodes can use advanced mathematical algorithms to recover data from damaged barcode symbols. Typical matrix QR codes include Aztec, Maxi Code, QR Code, Data Matrix, etc.

The third type is postal code. Encoding through bars of different lengths, mainly used for email encoding, such as Postnet, BPO 4-State, etc.

Among the two-dimensional barcodes introduced above, PDF417 code is widely used due to its open and commercialized decoding rules. It is an abbreviation for Portable Data File, which means that the barcode can be regarded as a file that can store a large amount of information and can be carried around. It was officially launched in 1992, and in 1995, the Barcode Committee of the Electronic Industries Association of America completed the draft of the two-dimensional barcode standard under the sponsorship of the American National Standards Institute, as a standard for the use of two-dimensional barcodes in the production and sales process of electronic products. PDF417 code is a multi line structure with the same number of data symbols per line. Rows are aligned and directly connected to each other, with a minimum of 3 lines and a maximum of 90 lines. The Data Matrix code is mainly used for identifying small components in the electronics industry, such as the back of Intel Pentium processors printed with this code. Maxi Code is developed by United Parcel Service in the United States for sorting and tracking packages. Aztec was launched by the American company Welling and can accommodate up to 3832 digits, 3067 letters, or 1914 bytes of data.

In addition, there are some newly emerging two-dimensional barcode systems. Including the UPS Code developed by Figrare lla and others from UPS, which is suitable for motion characteristics in distributed environments, this two-dimensional barcode is more suitable for automatic classification applications. Veritec Corporation in the United States has proposed a new two-dimensional barcode - Veritec Symbol, which is a binary data encoding system used on micro and small-sized products. Its matrix symbol format and image processing system have obtained US patents, and this two-dimensional code has higher accuracy and repeatability. In addition, WILJ WAN GILS and others from Philips Research Laboratory have proposed a novel QR code scheme, which uses standard geometric shape dots to form a dot matrix QR code representation for product identification marks on automatic production lines. This scheme consists of two main parts, one is the source encoding system, which is used to convert the encoding of identification marks into communication information words; The other part is the channel coding system, which is used for error detection and correction of random errors. There is also a type of two-dimensional barcode called dot matrix code, which not only has the characteristics of high information density, but also facilitates the printing of dot codes on mechanical components using carving and etching processes, and can be recognized by camera equipment and image processing systems. This is also a two-dimensional coding scheme with great potential for application.　

The development of two-dimensional barcode technology is mainly manifested in three trends: firstly, the emergence of encoding schemes with higher information density, which enhances the information input function of barcode technology; Secondly, the development of small, micro, and high-quality hardware and software has made barcode technology more practical and expanded its application areas; The third is the mutual penetration and promotion with other technologies, which will change the structure and performance of traditional products and expand the functionality of barcode systems.

2D barcode reader

There are several important parameters in a two-dimensional barcode reader: resolution, scanning background, scanning width, scanning speed, one-time recognition rate, and error rate. When selecting, it depends on the specific application. Ordinary barcode readers typically use the following three technologies: light pen CCD、 Laser, they all have their own advantages and disadvantages, and no reader can have advantages in all aspects.

The light pen is the first handheld contact barcode reader to appear. When in use, the operator needs to touch the surface of the barcode with the light pen and emit a small light spot through the lens of the light pen. When this light spot passes through the barcode from left to right, the light is reflected in the "empty" part and absorbed in the "bar" part. Therefore, a changing voltage is generated inside the light pen, which is amplified and shaped for decoding.

CCD is an electronic coupling device that is suitable for close range and contact reading. It uses one or more LEDs to emit light that can cover the entire barcode. Its focus is not on every "bar" or "space", but on the entire barcode and converts it into an electrical signal that can be decoded.

Laser scanners are non-contact, and laser readers are the only option when the reading distance exceeds 30cm. Its first reading recognition success rate is high, and the recognition speed is relatively faster than light pens and CCDs. Moreover, it has good recognition effect on barcodes with poor printing quality or blurry.

Radio frequency identification technology has changed the way barcode technology relies on "tangible" one-dimensional or two-dimensional geometric patterns to provide information, providing a larger amount of "intangible" information stored in it through chips. It first appeared in the 1980s and was initially applied in special industrial settings where barcode tracking technology was not available. For example, in some industries and companies, this technology was used for target positioning, identity confirmation, and tracking inventory products. Radio frequency identification technology started relatively late and has not yet developed a unified international standard. However, the introduction of radio frequency identification technology is not just about increasing information capacity. It is a revolution for computer automatic identification technology, and its powerful advantages will greatly improve the efficiency and accuracy of information processing.

3. Revolution from 'tangible' to 'intangible'

Huge advantages

Compared with barcode recognition systems, wireless radio frequency identification technology has many advantages: it automatically identifies target objects through radio frequency signals without the need for visible light sources; Having penetrability, data can be directly read through external materials, protecting the external packaging and saving unboxing time; RF products can operate in harsh environments with low environmental requirements; Reading distance is far, and data can be obtained without contact with the target; Support writing data without the need to create new labels; By using anti-collision technology, multiple RF tags can be processed simultaneously, suitable for batch identification scenarios; It can track and locate objects attached to RFID tags, providing location information.

Due to the advantages of RFID products, wireless radio frequency identification technology has developed rapidly abroad. It has been widely used in many fields such as industrial automation, commercial automation, transportation control management, etc., such as traffic monitoring systems for cars or trains, automatic toll collection systems for highways, item management, automated assembly line production, access control systems, financial transactions, warehouse management, livestock management, vehicle anti-theft, etc. In Australia, RFID technology is used for airport passenger baggage management, improving airport efficiency and achieving ideal benefits; On the other side of the earth, the European Community announced that new cars produced since 1997 must have anti-theft systems based on RFID technology; The Swiss National Railways will also install RFID automatic identification systems on all passenger trains in Switzerland, allowing dispatchers to monitor train operations in real-time. This not only facilitates management but also greatly reduces the likelihood of accidents; Lufthansa is trying to replace airline tickets with RFID electronic tags, thus changing the traditional way of purchasing and selling airline tickets. To this day, new applications of radio frequency identification technology continue to emerge endlessly.

Due to the miniaturization of RFID chips and the practicality of high-performance chips, RFID tags not only help managers in different fields track the location and handling of items, but also report other information attached to the tag in real time, such as temperature and pressure. Radio frequency tags provide this type of information through readers connected to data networks. So far, radio frequency identification tags have mainly been used as an extension of barcodes in fields such as factory automation or inventory management. However, ultimately, smaller size radio frequency identification tags will be applied in more advanced fields. For example, RFID tags can promote the application of network appliances. If appliances have network functions, users can control them even outdoors. For example, they can check the food in the refrigerator, help users decide what items to buy, and select the cooking method of food on wireless operation terminals. Currently, manufacturers of electrical equipment and household appliances have started developing universal software and hardware, and are considering establishing application standards for RFID tags on various household appliances. Applying RFID tags to hospitals can also bring benefits. As soon as a patient enters the hospital, they wear a tag that contains the patient's identification information. Doctors and nurses can identify the patient's identity through the data on the tag, avoiding misidentifying the patient. Tags and readers can also help doctors and nurses confirm whether the medication used is appropriate, thereby avoiding medical accidents.

4. RFID is entering the practical stage

According to statistics, there are currently about 5000 RFID systems installed worldwide, with actual annual sales of approximately 964 million US dollars. However, they are mainly used in limited fields such as pet and wildlife tracking, road and parking fees. In fact, RFID is expected to have a significant impact in many more areas. Nowadays, a considerable number of enterprises have experimented with applying it to some new fields.

Gillette is the world's largest manufacturer of razors, and its products are often favored by thieves due to their small size and high unit price. To this end, Gillette has decided to adopt radio frequency identification technology to prevent product theft. A project execution committee composed of senior managers and a radio frequency identification project office have been established to guide and coordinate the daily management of the project, and relevant responsibilities have been included in the performance evaluation of employee goal management. Gillette will divide the project into two phases and implement it from two aspects: internal operations and retail shelf management. Firstly, Gillette will choose "Fengsu 3" to conduct shelf trials in a few places, and then promote it to all 8 product lines after success; In the second phase, Gillette plans to integrate it into the entire supply chain, achieving seamless tracking and management of the entire process of products from factories to retail distribution centers, to shelves, and finally to the hands of end consumers.

At present, Gillette has completed the first phase of tests with Wal Mart and Tesco in Boston, USA and Cambridge, UK respectively: Gillette implanted RFID tags into the packaging of "Spike Speed 3", and installed readers on the shelves of retailers. If a customer takes more than one shaver at a time, the system will remind the clerk to check whether theft has occurred, or even take photos automatically. When the inventory on the shelves is reduced to a certain level, the system will send a signal to replenish. The test results are very satisfactory. It is said that the second phase of the experiment is also about to officially start. It is worth mentioning that Gillette has ordered a total of 500 million RFID tags from Allen Technologies, one of the RFID tag manufacturers. This is undoubtedly a significant milestone in the large-scale commercialization process of low-cost RFID tags.

Metro AG Group, a famous international retail enterprise, has recently adopted Philips Semiconductor's RFID solution in its business operations. This technology can help it improve the efficiency of the supply chain in retail and improve the shopping experience of consumers. This radio frequency identification technology can identify products in real time, prevent thieves, track inventory, and also view the status of customer loyalty cards. The system operates at a frequency of 13.56MHz, with an effective recognition range of 1.5 meters. It is connected to an RFID multimedia studio, and consumers can simply scan a CD or DVD to see an introductory preview of the album or movie they are looking to purchase. Cosmetics and food have also been labeled and placed on smart shelves, which can provide real-time inventory and shelf life control, update sales data in a timely manner, and detect misplaced items.

Recently, Wal Mart also said that it would no longer purchase goods from suppliers that did not use RFID technology in the future, which shocked the application software industry greatly. Now, Sun Microsystems is developing a corresponding middleware product to manage product data obtained from RFID systems. The product is currently in the testing phase and is expected to be launched for commercial use this year. In addition, Sun Microsystems is also developing information service software that complies with the RFID industry standard EPC.

Once the chips and tags used for radio frequency identification are released, specialized software is needed to manage this data. Fortunately, many large software developers and system integrators have begun to enter the field of RFID, with SAP, Manhattan Associates, IBM, and other companies launching their own solutions. SAP has publicly announced that it is collaborating with Procter&Gamble on a series of technological innovations to merge RFID data into the SAP/R3 system. The system is called AutoID, which can protect the system from only obtaining valuable data and avoid interference from erroneous data. In addition, IBM has also demonstrated its radio frequency identification system at the Electronic Code Symposium. The company can provide a complete solution for radio frequency identification, which can achieve a complete set of business processes from manufacturers, distributors, and retailers without crossing systems. However, integration work is still quite challenging. According to the developer, the price is quite expensive, and it is quite challenging to launch a complete RFID software system before the deadline of January 2006.

In addition, tags will also be a huge market, especially now the price of RF tags is 20 cents to 30 cents. Because the buyer is in the leading position in the market at present, Wal Mart may require the price of RFID tags to be reduced to an acceptable level, but it is unknown whether the supplier can provide the corresponding technology.