1, cheap and practical basic information technology

◆ An automatic identification technology produced and developed in computer application practice.

◆ It aims to realize automatic scanning of information. It is an effective means to collect data quickly, accurately and reliably.

The application of barcode technology has solved the problems and bottlenecks of data entry and data collection, and provided strong technical support for supply chain management.

◆ Fast input speed.

◆ Large amount of information

◆ High precision

◆ Low cost

◆ Strong reliability

Bar code technology provides us with a way to identify and describe goods in logistics. With the help of automatic identification technology, POS system, EDI and other modern technical means, enterprises can always know the position of related products in the supply chain and respond immediately.

2. The development of bar code

As an automatic data acquisition unit technology in logistics information system, barcode technology is an important technology to realize automatic collection and input of logistics information. Bar code first appeared in the 1940s, but it has been rapidly applied and developed in recent 20 years. In the 1950s, there were reports about the use of bar codes on American railway vehicles. At present, all railway vehicles in the United States have ACI (Automatic Vehicle Identification) bar code marks. As early as the late 1940s, two American engineers, Joe Wood Rand and Bunning Silver, began to study the use of codes to represent food items and the corresponding automatic identification equipment, and obtained an American patent at 1949. This code pattern is very similar to a miniature archery target, which is called "bull's-eye" code. Draw concentric rings and blanks of the target. In principle, the "bull's-eye" code is very similar to the later bar code symbols. Unfortunately, the commodity economy was not very developed at that time, and the technology did not reach the level of printing this code. Twenty years later, Joe Woodland, as an engineer of IBM, became the founder of ——UPC code, a unified code in North America. Girad hissel et al. applied for a patent in 1959, in which each number from 0 to 9 is represented by seven parallel bars, but this kind of encoder is difficult to identify and read. However, this idea promoted the emergence and development of barcode coding system. Soon, E.F. brinker obtained a patent for marking bar codes on trams. In the late 1960s, Sylvania Vegna understood the bar code system used in the North American railway system.

3. The function of barcode in logistics information system.

As a timely, accurate, reliable and economical data input method, barcode has been adopted by logistics information system. It has been widely used in industrialized countries and has become a unique "identity card" for goods in the world.

Bar code technology has been widely used in Europe, America, Japan and other countries, and has been rapidly popularized around the world, and its application fields are still expanding. Because of the use of bar code, consumers have a sense of security in the quality of goods, and bar code can also play an important role in identifying counterfeit and shoddy products and preventing counterfeiting. Because bar code technology is advanced, applicable, easy to master and quick to get results, it is necessary to give full play to its advantages in information (data) collection. Whether in the process of warehousing, storage, shelving or settlement with customers, we need to face the problem of how to input the information of huge data goods (whether it is whole package packaging or single retail after unpacking) into the computer. If the bar code symbol is printed on the packaging of a single commodity, and the bar code reader is used, we can quickly, accurately and timely grasp the variety (article number), quantity, unit price, manufacturer, production date and other information of the commodity. This not only improves the efficiency, but also attracts more customers, reducing or eliminating the congestion and queuing phenomenon when customers check out and pay after purchase. As the main automatic identification technology in China, bar code technology will be widely used in industrial automation control and various management information systems, and will penetrate into multi-technical fields and high-tech products.

The logistics information system adopts bar code technology, and the information is collected and input by computer. This will greatly improve the practicability of many computer management systems. The application and popularization of bar code originated from the modernization of commodity management, that is, the application of POS system. For example, there are more than 220,000 kinds of goods in American supermarkets. Every year, about 10000 kinds of new goods enter the market, and 10000 kinds of old goods are taken off the shelves, accounting for 50% of the total. Such a heavy workload is hard to cope with without bar code and POS system. Today, Japan is at the forefront of the world in the application of POS system. At present, there are 48,000 manufacturers in Japan, and about 6,543.8 billion kinds of goods adopt EAN codes, and quite a few businesses use POS systems. POS system is not limited to grocery stores, but also some specialty stores (such as medicine, cosmetics, tobacco and alcohol, etc. ) has also established a POS system. At present, not only the POS system is widely used, but also many countries have established market data exchange centers to communicate the information between production, supply and sales, establish trade data exchange institutions, collect and summarize the sales information of various stores and commodities in time, and feed it back to manufacturers in time. In this way, manufacturers can timely and accurately understand the sales, purchase and price of goods, analyze the psychology of consumers, predict the market and organize the supply of goods in time. Retailers can adjust the sales plan and purchase situation in time according to the situation.

1) Transportation industry

According to the regulations of the International Transport Association, in the transportation of goods, the bar code symbol must be affixed to the package of goods to carry out automatic statistical management of the transported goods. In addition, bar code, as a timely, accurate, reliable and economical data input means, has been adopted by logistics information systems, such as railway and highway ticket automatic ticketing and checking systems, highway ticket collection station automation, and the role of bar code in warehouse and cargo bus logistics information systems. It has been widely used in industrialized countries and has become a unique and universal "ID card" commodity. Bar code technology has been widely used in Europe, America, Japan and other countries, and it is necessary to use bar code technology to collect data in real time in the rapid flow automation management all over the world.

2) Posts and telecommunications industry

Sorting and mailing mail is a very heavy job, which occupies most of the workload of post and telecommunications staff. By pasting or printing bar code symbols on the mail, the corresponding information is input by the bar code reading equipment, and the automatic management of sorting and listing is realized. For example, if the 6-digit postal code is replaced by a bar code symbol, letters and post offices (offices) can be marked with the corresponding bar code as their codes by computers, and information can be read by bar code reading equipment, thus realizing automatic computer registration.

3) Logistics industry

Logistics industry is a very important application aspect of barcode technology. Bar code management can be realized in the aspects of material storage, classification, storage, inventory and transportation. In terms of general merchandise circulation and sales, in addition to the automatic management of export commodity bar codes, the military should start to develop special cash registers and integrated management systems suitable for shopping malls in China, and try them out in high-rise shopping malls and gradually promote them. POS system consists of several subsystems, among which cash register (also called cash register) is a combination of personal computer and decoder. It can not only automatically recognize bar code symbols, but also process data and print out a shopping list, including product name, price, quantity, total amount and date, which customers can use as shopping receipts. The computer in the system is used for comprehensive data processing, so the database and application software should be established in advance. This is conducive to the comprehensive analysis of commodity sales according to the daily report of each terminal, providing market trends in time, and determining the order plan accordingly, thus ensuring the normal operation of business activities. Because of the bar code technology, it is convenient and fast, and the accuracy of information is guaranteed.

4) Retail industry

Supermarket: barcode-scanner -POS-EIQ analysis (category, quantity and quality) < BR> Wal-Mart: barcode scanner (fixed and mobile) -POS-EIO analysis (category, quantity and quality)

5) Other industries

Practice shows that the direct benefit brought by adopting bar code management system in stores can reach 6. 12% of turnover. More importantly, it not only promotes the management of commodity circulation, so that production enterprises can effectively grasp the quantity of spare parts, spare parts and semi-finished products and the inventory of finished products and raw materials in each process on the production line, but also can quickly obtain sales information through computer networks, timely and effectively predict market trends, and establish an efficient operation mechanism integrating production, supply and sales. Because modern industrial and commercial trade is extremely active and there are many kinds of goods, it is possible to adopt article coding. The adoption of POS system in retail industry not only improves the settlement speed, but also avoids human error and greatly increases the number of customers. For customers, the waiting time for shopping can be greatly reduced, and the shopping list is convenient for family bookkeeping. The application of bar code management system also creates favorable conditions for service personnel in shopping malls not to consult customers.

Bar code technology can also be used for customs declaration management and customs commodity inspection; Used for entry-exit visa management, passport, ID card and management of public security system; In enterprises and institutions, you can use personnel file management, equipment management, meeting management, attendance management, college entrance examination self-study management and various ticket management. Bar code technology provides a very simple and convenient language for commodity management, trade between countries and automatic management in various fields.

As a new information storage and transmission technology, 2D barcode DF4 17 has been widely used in national defense, public security, transportation, medical care, industry, commerce, finance, customs and government management. The technology of PDF4 17 has been used in driver's license, American military card and military medical card in more than ten states such as Arizona. Personal information and photos on documents are encoded in two-dimensional bar codes, which can not only realize automatic reading of identity documents, but also effectively prevent the occurrence of forged documents. Many countries, such as the Philippines, Egypt, Bahrain and so on. Two-dimensional bar codes are also used on ID cards or driver's licenses. According to incomplete statistics, more than 40 countries have accurately adopted the two-dimensional barcode PDF4 17 on their ID cards or driver's licenses. After China resumed the exercise of sovereignty over Hong Kong, the new version of SAR passports issued by Hong Kong residents adopted the technology of 2D barcode PDF4 17. Besides documents, two-dimensional bar codes are also widely used in industrial production, national defense, finance, medicine and health, commerce, transportation and other fields. The advantages of two-dimensional bar code are low cost, information can move with the carrier, and it does not depend on database and computer network, so it has strong security and anti-counterfeiting performance. Combined with the problems of large population, weak foundation, difficult investment in computer network and machine-readable anti-counterfeiting of documents in China, it can be widely used in passports, identity cards, driver's licenses, temporary residence permits, driving licenses, military cards, health cards, insurance cards and other documents that need to uniquely identify individuals. Any forms such as customs declaration form, tax return form and insurance registration form that need to be repeatedly entered or prohibited from being forged or deleted can be coded with PDF4 17 bar code to solve the problem of automatic entry of forms and prevent tampering with the contents of forms. The production and wiring of electromechanical products such as automobile assembly line and electronic product assembly line can adopt two-dimensional bar code, and automatic data exchange can be realized through two-dimensional bar code. Two-dimensional bar code has a broad application prospect in the transportation and mailing of luggage items in China.

Second, the classification of bar codes

1, classified by code system

1) UPC code

1973, the United States took the lead in applying UPC code in domestic commercial systems, and Canada also adopted UPC code in commercial systems. UPC code is a fixed-length continuous digital coding system, and its character set is numbers 0~9. It adopts four element widths, and each bar or space is 1, 2, 3 or 4 times the unit element width. There are two kinds of IPC codes, namely UPC-A code and UPC-E code.

2) EAN code

1977, EuropEAN countries formulated European article code ean code according to UPC code standard, which is compatible with UPC code and has the same symbol system. The character numbering structure of EAN code is the same as UPC code, and it is also a continuous digital code system with fixed length. The character set is numbers 0~9. It adopts four element widths, and each bar or space is 1, 2, 3 or 4 times the unit element width. There are two types of EAN codes, namely EAN- 13 code and EAN-8 code.

3) Span 25 yards

Cross-25 code is a continuous self-checking digital code system with variable length, and its character set is numbers 0~9. Two element widths are adopted, and each bar and space is a wide or narrow element. The number of coded characters is even, all data at odd positions are coded as strips, and data at even positions are coded as blank. If odd numbers of data are encoded, a 0 is added before the data to make the number of bits of the data even.

4) Size 39

Code 39 is the first alphanumeric code system. 1974 was introduced by Intermec. This is a discrete self-correcting alphanumeric coding system with equivalent length. Its character set is the numbers 0-9, 26 capital letters and 7 special characters (-,. , space,/,%, ￥), ***43 characters. Each character consists of 9 elements, including 5 bars (2 wide bars and 3 narrow bars) and 4 spaces (1 wide spaces and 3 narrow spaces), which is a discrete code.

5) Kudbama code

The code bar appearing in 1972 is a continuous self-checking digital code system with variable length. Its character set is the numbers 0-9 and six special characters (-,:,/,. ,+,￥), * * 16 characters. Commonly used in warehouses, blood banks and air express parcels.

6) 128 code

The code 128 appears in 198 1, which is a continuous self-checking variable-length digital code system. It adopts four element widths, each character consists of three bars and three spaces, and the width of * * 1 1 element is also called (11,3) code. It consists of 106 different bar code characters, and each bar code character has three character sets with different meanings, A, B and C. With these three alternating character sets, 128 ASCII codes can be encoded.

7)93 yards

Code 93 is a continuous alphanumeric code system with variable length. Its character set becomes a number. 0-9, 26 capital letters and 7 special characters (-,. , space,/,+,%, @) and four control characters. Each character consists of 3 bars and 3 bars, and the width is ***9 elements.

8) Size 49

Code 49 is a multi-line continuous alphanumeric code system with variable length. Appears in 1987, and is mainly used for symbols on small commodity labels. Adopt a variety of element widths. Its character set is the numbers 0-9, 26 capital letters and 7 special characters (-,. , spaces,%,/,+,%, ￥), three function keys (F 1, Tuo, F3) and three conversion characters, with 49 characters.

9) Other coding systems

In addition to the above code, there are other codes. For example, code 25 appearing in 1977 is mainly used for electronic component labels; The code of the matrix 25 is a variant of the code 1 1; Nixdorf code has been replaced by EAN code. Plessy code appeared in 197 1 May, and was mainly used in libraries.

2. Classification by dimension

1) ordinary one-dimensional barcode

Ordinary one-dimensional bar code has been popularized and widely used since it came out. However, due to the small information capacity of one-dimensional bar codes, for example, the bar codes on commodities can only hold Arabic numerals of 13, and more information describing commodities can only rely on the support of databases. Without a pre-established database, this bar code will become passive water, and the application scope of bar code will be limited to some extent.

2) 2D barcode

In addition to the advantages of ordinary bar code, two-dimensional bar code also has the advantages of large information capacity, high reliability, strong security and anti-counterfeiting, easy manufacture and low cost. & ltBR & gt 199 1 year, American Symbol company officially launched a two-dimensional code named PDF4 17, referred to as "portable data file". FDF4 17 barcode is a portable data file with high density and high information content, and it is an ideal means to realize automatic storage, carrying and reading of large-capacity and high-reliability information such as certificates and cards.

3) Multi-dimensional barcode

Since 1980s, people have been studying how to improve the information density of bar code symbols. Multi-dimensional barcode and container barcode have become the direction of research, development and application. & ltBR & gt information density is an important parameter to describe bar code symbols, that is, the number of letters that may be included in a unit length, which is usually recorded as: number of letters /cm. The main factors affecting the information density are the strip structure and the width of the narrow element system. & ltBR & gt code 128 and code 93 are successful attempts to improve the density. 128 yard market 198 1 year was recommended for application; Code 93 was put into use at 1982. The symbol density of these two codes is nearly 30% higher than that of 39 codes. & ltBR & gt With the development of barcode technology and the diversification of the three systems of barcode, the standardization of barcode becomes more and more important. Therefore, the military standard 1 189 was formulated one after another. The ANSI standard MH 10.8M spans 25 yards, 39 yards and Coda bar codes. At the same time, some industries have begun to establish industry standards to meet the needs of development. Since then, David Ariel has developed another 49 yards. This is a non-traditional bar code symbol with higher density than the previous bar code symbol. Ted Williams)GFI988 introduces 16K code, which is similar to 49 code in structure. This is a relatively new coding system, which is suitable for laser system.

Third, the bar code structure

1) Basic terms of barcode

Bar code is an information code, which uses special graphics to represent numbers, letters and some symbols. Figure A is the bar code of Fu Miao Continental Cake of Hangzhou Dingyuan Food Co., Ltd. The bar code consists of a group of bars and spaces with the same width and reflectivity, which are combined according to certain coding rules to represent a symbol with complete data. Usually, human-readable characters are marked under bar code symbols.

Bar code element: used to represent bars and blanks of bar code, referred to as element for short. & ltBR & gt barcode characters: a group of barcode elements used to represent numbers, letters and special symbols. & ltBR & gt bar: an element with low reflectivity in a bar code symbol. & ltBR & gt empty: the element with high reflectivity in the barcode symbol. & ltBR & gt bit space: in a bar code symbol, it is located between two adjacent bar code characters and is a space representing any information. & ltBR & gt Bar height: the longer of the two dimensions of the bar. & ltBR & gt Bar code width: in the bar code symbol, the length of dead zones on both sides is not included. & ltBR & gt unit element length: in the bar code symbol, the nominal width of a narrow element is the unit element width, which is represented by X .. BR> Binary Wide Barcode: If there are only two element widths in a barcode character, namely, a wide element and a narrow element, this coding system is called a multi-element wide barcode. & ltBR & gt Multi-element wide bar code: If there are three or more elements in the bar code symbol, it is called a two-element wide bar code. & ltBR & gt barcode logical value: for a long code with two elements, the logical value of the wide element is 1 and the logical value of the narrow element is 0; For a wide barcode with multiple elements, the logical value is 1 if the cell element width is a bar, and 0 if the cell element width is empty. & ltBR & gt continuous code type and discrete barcode: in barcode symbols, if there is a space between two adjacent barcode characters, this code is called discrete barcode, as shown in Figure B, otherwise it is called continuous barcode. & ltBR & gt Dead Zone Start Character Data Character Check Character End Character Dead Zone

& ltBR & gt the structure of bar code symbol in figure b

Fixed-length and variable-length bar codes: in bar code symbols, if the number of symbols and bar characters is fixed, this coding system is called fixed-length bar code; Otherwise it is called variable scale bar code. & ltBR & gt self-checking barcode: If a printing error does not cause one character to be translated into another character in this code system, this code system is called self-checking barcode. & ltBR & gt(n, k) code: a continuous bar code with multiple element widths, also known as (n, k) code. N refers to the number of single element widths contained in bar code symbols, and k refers to the number of bars or spaces in characters. & ltBR & gt Bar code symbol density: refers to the number of bar code characters that can be represented in a unit length. & ltBR & gt barcode character set: the barcode character set refers to the range of given data characters in the barcode system. A given range of data characters in various bar code systems. There are two main character sets in various bar code systems. One is the numeric character set, which contains the numbers 0-9 and some special characters. The other is alphanumeric character set, including numbers 0~9, letters A~z and some special characters. & ltBR & gt stain: A point in a blank and quiet area, similar to the reflectivity of a bar. & ltBR & gt defect |: the ratio of the difference between the empty reflectivity RL and the reflectivity RD of the test strip to the empty reflectivity RL, which is represented by the symbol PCS, namely:

2. The structure of bar code symbols

A complete bar code symbol consists of two dead zones, a start character, a data character, a check character (optional) and a stop character. Figure B shows the complete structure of bar code symbols, in which: BR> dead zone: no printed symbols or bar code information. It is usually white and located on both sides of the bar code symbol. The function of the dead zone is to prompt the reader, that is, the scanner, to prepare to scan the bar code symbol. & ltBR & gt Start character: The first character of a bar code symbol is the start character, and its special blank structure is used to identify the beginning of the bar code symbol. The reader first confirms the existence of this character, and then processes a series of pulses obtained by the scanner. Data characters: composed of bar code characters, used to represent some original data information. & ltBR & gt Termination Character: The last character of the bar code symbol is the termination character, and its special bar and empty structure is used to mark the end of the recognizable code symbol. When the reader recognizes the termination character, it can be known that the bar code symbol has been scanned. If the bar code symbol ends. The reader transmits the data address to the computer and provides the feedback of "effective reading" to the operator. The use of termination characters avoids the input of incomplete information. When a check character is used, the termination character also instructs the reader to perform a check calculation on the data character. The bar structure of & ltBR & gt start character, end character and empty structure is usually an asymmetric binary sequence. This asymmetry allows the scanner to scan in two directions. When the bar code symbols are reversely scanned, the reader will rearrange the bar code symbols in the correct order before checking the calculation and transmission information. & ltBR & gt check character: the check character is defined in the barcode system. The check character of some codes is required, and the check character of some codes is optional. Check characters are determined by performing arithmetic operations on data characters. When each character in the symbol is decoded, the decoder will perform the same arithmetic operation and compare the result with the check character. If the two sides are consistent, the information read in is valid.

Fourth, the barcode reader.

1. Composition of automatic bar code recognition system

2, bar code reading equipment and classification

Bar code reading equipment can be divided into two categories.

1) online reader

According to their functions and uses, online readers can be divided into multifunctional reading and various online special readers. Generally, this kind of reader is directly powered by AC power supply and connected with computer or communication equipment through cables to transmit data. The invention not only has the function of identifying various commonly used codes, but also can add programmable function, displayable function and multi-computer networking communication function according to different needs.

2) Portable reader

Portable readers are equipped with data storage, usually powered by batteries, and are suitable for offline use. After collecting data, first store the data and then dump it to the host. At present, a portable reader that can store tens of thousands of bar codes has been introduced in the international market, which is widely used in warehouse management, commodity inventory and various field operations. As the input device of the terminal, the scanner has developed rapidly, and the forest can be divided into contact, non-contact, temple suction and fixed scanners. At present, there are three commonly used scanners: pen scanner, CCD scanner and laser gun scanner. Scanner and decoder can be independent of each other or integrated together. The scanner should choose the corresponding scanning wavelength, resolution and scanning depth of field according to its different uses. With the development of science and technology, the innovation of bar code printing technology and the corresponding equipment will be exhibited soon, and people can choose according to their own needs. Such as various film production and plate-making technologies; Letterpress printing and offset printing technology; Suitable for small batch occasions and various dot matrix printers, laser printers, thermal printers, and on-site special coding machines. At present, the bar code technology products of the United States, Japan and other countries still occupy the international market. Bar code technology is the most widely used, but people are most familiar with the POS system in the field of general commodity circulation and sales, commonly known as sales terminal or scanning system at home and abroad. POS system is widely used in North America and Europe and Japan, with a penetration rate of over 95%. Global adoption of EAN and its coding trend. Japan is the largest user of EAN system, with more than100,000 stores adopting POS system and more than 65,438+0,000,000 kinds of goods adopting bar codes.