Let me briefly talk about the concept of bar code. Bar code or barcode is a graphic identifier that arranges several black bars and blanks with different widths to represent a group of information according to certain coding rules. Common bar codes are parallel lines composed of black bars (referred to as bars) and white bars (referred to as spaces) with great differences in reflectivity. Barcode can indicate the country of production, manufacturer, commodity name, date of production, book classification number, starting and ending place, category, date and many other information, so it has been widely used in many fields such as commodity circulation, book management, postal management, banking system and so on. First, the history of bar code Bar code technology was first produced in the jittery 1920s, and was born in the laboratory of Westinghouse. An eccentric inventor named JohnKermode "whimsically" wants to realize the automatic sorting of postal documents. At that time, every idea about the application of electronic technology was very novel. His idea is to put a barcode on the envelope, and the information in the barcode is the address of the recipient, just like today's postal code. For this reason, Comander invented the earliest bar code recognition, and the design scheme is very simple (note: this method is called modular comparison method), that is, one represents the number "1", two represents the number "2", and so on. Then, he invented a bar code reading device composed of basic components: scanner (which can emit light and receive reflected light); A method for measuring the band and space of reflected signal, namely edge positioning coil; And a method of using the measurement result, namely a decoder. Comander's scanner uses a newly invented photovoltaic cell to collect reflected light. "Empty" reflects a strong signal, while "bar" reflects a weak signal. Unlike today's high-speed electronic components, Comander uses magnetic coils to measure "bars" and "spaces". Just like a child connecting a wire to a battery and winding it around a nail to clamp paper. Comander uses a coil with an iron core to attract the switch when it receives the "empty" signal, and release the switch when it receives the "bar" signal to connect the circuit. So the earliest bar code readers were very noisy. The switch is controlled by a series of relays, and the "on" and "off" are determined by the number of "paper strips" printed on the envelope. In this way, the bar code symbol directly sorts the letters. Shortly thereafter, DouglasYoung, Comander's collaborator, made some improvements to Comander's code. Comande code contains so little information that it is difficult to compile more than ten different codes. On the other hand, Yang code uses fewer bars, but takes advantage of the change of the space between bars, just like UPC barcode symbols today use four different bar sizes. The new barcode symbol can encode 100 different regions in the same space, while Comander code can only encode 10 different regions. It was not until 1949 that the omni-directional bar code symbol invented by Noam Woodland and Bernard Seval was first recorded in the patent literature. Prior to this, there was no record of bar code technology and no precedent for practical application. The idea of Noam Woodland and Bernard Searwar is to use the vertical "strips" and "spaces" of Comander and Yang, and bend them into rings, much like archery targets. In this way, the scanner can decode the bar code symbol by scanning the center of the graph, regardless of the direction of the bar code symbol. In the process of constantly improving this patented technology, a science fiction writer IsaacAzimov described an example of automatic identification using a new information coding method in his book TheNakedSun. At that time, people thought that the barcode symbol in this book looked like Fang Gezi's chessboard, but today's barcode professionals will immediately realize that it is a two-dimensional matrix barcode symbol. Although this bar code symbol has no direction, no positioning and no timing, it is obvious that it represents a digital code with high information density. It was not until 1970 that IterfaceMechanisms developed "two-dimensional code" that the printing and reading equipment of two-dimensional matrix bar code came out at a price suitable for sale. At that time, two-dimensional matrix bar code was used to realize the automation of newspaper typesetting process. Two-dimensional matrix bar code is printed on paper tape and scanned and read by today's one-dimensional CCD scanner. The light emitted by CCD shines on the paper tape, and each photocell is aimed at different areas of the paper tape. Each photovoltaic cell outputs different patterns according to whether the bar code is printed on paper tape or not, and combines them to generate high-density information patterns. In this way, a single character can be printed in the same size space as a single bar in the early Comander code. Timing information is also included, so the whole process is reasonable. When the first system entered the market, the price of the whole set of equipment including printing and reading equipment was about $5,000. Shortly thereafter, with the continuous development of LED (light emitting diode), microprocessor and laser diode, a new symbol (symbolism) and its explosion came, which was called "barcode industry". Today, it is difficult to find companies or individuals who have not been directly exposed to fast and accurate barcode technology. With the rapid technological progress and development in this field, more and more application fields are developed every day. Before long, bar codes will be as popular as light bulbs and transistor radios, which will make everyone's life easier and more convenient. [Edit this paragraph] Second, the recognition principle of barcodes To convert barcodes compiled according to certain rules into meaningful information, it needs to go through two processes: scanning and decoding. The color of an object is determined by the type of light it reflects. White objects can reflect various wavelengths of visible light, while black objects absorb various wavelengths of visible light. Therefore, when the light emitted by the light source of the barcode scanner is reflected on the barcode, the reflected light shines on the photoelectric converter inside the barcode scanner, and the photoelectric converter converts it into corresponding electrical signals according to the reflected light signals with different intensities. According to different principles, scanners can be divided into three types: light pen, CCD and laser. The electrical signal is output to the amplification circuit of the barcode scanner to enhance the signal, and then sent to the shaping circuit to convert the analog signal into a digital signal. The widths of white bars and black bars are different, and the duration of corresponding electrical signals is also different. Then the decoder judges the number of bars and spaces by measuring the number of pulse digital electrical signals 0, 1. The width of bars and spaces is determined by measuring the duration of 0, 1 signal. The data obtained at this time is still quite confusing. In order to know the information contained in bar code, it is necessary to convert bar code symbols into corresponding digital and character information according to the corresponding coding rules (such as EAN-8 code). Finally, the detailed information of the article is identified by the computer system, and the data is processed and managed. [Edit this paragraph] III. Advantages of barcode 1. Strong reliability. The reading accuracy of bar code far exceeds manual recording, and an error will appear every 15000 characters on average. 2. High efficiency. The reading speed of bar code is very fast, which is equivalent to 40 characters per second. 3. Low cost. Compared with other automatic identification technologies, barcode technology only needs a small sticker and a relatively simple optical scanner, and the cost is quite low. 4. Easy to make. Bar code writing is very simple, just need to print, so it is called "printable computer language". 5. Simple operation. Bar code recognition equipment is simple in structure and convenient to use. 6. Flexible and practical. Bar code symbols can be input by manual keyboard, can also be combined with related equipment to realize automatic identification, and can also be linked with other control equipment to realize automatic management of the whole system. [Edit this paragraph] 4. Scanning barcodes Scanning barcodes requires a scanner. The scanner uses its own light source to illuminate the bar code, and then uses a photoelectric converter to receive the reflected light and convert the brightness of the reflected light into a digital signal. No matter what rules are adopted to print bar codes, they are all composed of dead zones, start characters, data characters and end characters. Some barcodes also have a check character between the data character and the termination character. ▲ Quiet zone: As the name implies, an area that does not carry any information plays a prompting role. ▲ Start character: the first character with special structure. When the scanner reads this character, it begins to read the code formally. ▲ Data characters: the main content of bar code. ▲ Check the characters: check whether the read data is correct. Different coding rules may have different checking rules. ▲ Termination character: the last character, which is also a special structure, is used to inform the end of static code analysis, and also plays a role in checking calculation. In order to facilitate bidirectional scanning, the start and stop characters have asymmetric structures. Therefore, the scanner can automatically rearrange the barcode information when scanning. There are three kinds of light pens in bar code scanner: light pen, CCD and laser. The most primitive scanning method needs to move the light pen manually and touch the bar code. ▲CCD: scanner with CCD as photoelectric converter and LED as light source. In a certain range, automatic scanning can be realized. And can read bar codes on various materials and uneven surfaces, and the cost is relatively low. But the scanning distance is shorter than that of the laser type. ▲ Laser: a scanner with laser as the light source. It can also be divided into linear, full angle and so on. Linetype: mostly used for hand-held scanners, with long action distance and high precision. All angles: mostly horizontal, with high degree of automation, which can automatically read bar codes in all directions. [Edit this paragraph] V. Advantages of barcode technology Barcode is by far the most economical and practical automatic identification technology. Bar code technology has the following advantages: a. Fast input speed: compared with keyboard input, bar code input speed is five times that of keyboard input, which can realize "instant data input". B High reliability: the error rate of keyboard input data is 300%, the error rate of optical character recognition technology is110000, and the error rate of barcode technology is less than110000. C. The amount of information collected is large: the traditional one-dimensional bar code can collect dozens of characters at a time, and the two-dimensional bar code can carry thousands of characters, and it has certain automatic error correction ability. D. Flexible and practical: Bar code identification can be used as a means of identification alone, can also be combined with related identification equipment to realize automatic identification, and can also be connected with other control equipment to realize automatic management. In addition, the bar code label is simple to make, has no special requirements for equipment and materials, and the identification equipment is simple to operate without special training, and the equipment is relatively cheap. [Edit this paragraph] VI. Uniqueness of bar code coding rules: the same product with the same specification corresponds to the same product code, and the same product with different specifications should correspond to different product codes. According to the different properties of products, such as weight, packaging, specifications, smell, color, shape, etc. , give different commodity codes. Permanence: once the product code is assigned, it will not be changed, and it is lifelong. When the product is no longer produced, its corresponding product code can only be shelved and cannot be reused and redistributed to other commodities. Meaningless: In order to ensure that the code has enough capacity to meet the needs of frequent product updates, it is best to use meaningless sequence codes. The formula of barcode check code is 1. First, number the bar code as "... 4, 3, 2, 1." from right to left, add and sum all the numbers on even digits starting from the second serial number, multiply the calculated sum by 3, then add and sum all the numbers on odd digits starting from the third serial number, add the calculated sum with the product of the sum of numbers on even digits multiplied by 3, and then get the sum. Subtract this sum by the smallest multiple larger than this sum by 10 to get the check code. For example, this barcode is: 977167121601x (x is the check code). 1, 1+6+2+7+ 1+7=242, 24× 3 = 723,0+1+65438+6+7+9 = 244 and 72+24. This barcode is 9771671216014. [Edit this paragraph] VII. The coding difference of barcode UPC: (Unified product code) can only indicate that the number has four versions, A- 12-bit version E-7. The last digit of the number is the check digit, with the size of 1.5 ".The background is clear and clear. It is mainly used in the United States and Canada. When UPC is decoded into twelve bits, it is defined as follows: the first bit = digital identification (established by UCC (Unified Coding Committee)). 2-6 digits = identification number of the manufacturer (including the first digit), 7 digits-1 1 = unique product code of the manufacturer, and 12 digits = usedforerrordetection) code 3f93f9. 43 characters: A-Z, 0-9,-. The length of $/+%.PACE barcode can be changed, and "*" is usually used as the starting and ending symbol. The code density of the check code is 3-9.4 characters/inch, and the blank area is 10 times that of the narrow strip, which is used for industry, books and automatic ticket management. Code 128: represents high-density data, with variable-length strings and symbols containing check codes. There are three different versions: A, B A, B, and C. There are 128 characters in the three sets of strings of A, B A, B, and orC, which are used in industry, warehouse, retail and wholesale. Interleaves 2-of-5(i2of 5): It can only represent numbers 0-9, and it is a continuous barcode. All bars and spaces represent codes. The first number begins with a bar, and the second number consists of spaces. The blank area is 10 times wider than the narrow strip. Used in commodity wholesale, warehouse, airport, production/packaging identification and industry, with high bar code recognition rate. Codabar: It can represent the numbers 0-9, the characters $,+,-,and the four characters A, B and CD that can only be used as start/stop symbols. Its length is variable and there is no parity bit. It is used in material management, libraries, blood stations and current airport parcel delivery. The blank area is wider than the narrow bar 10, and each character is represented as a discontinuous bar code. Codabar, also known as NW7, is called in Japan. PDF4 17 (two-dimensional code): a bar code composed of multiple lines, which can store a large amount of data without connecting to a database. It can be used in hospital, driver's license, material management and cargo transportation. When the bar code is damaged to a certain extent, error correction can make the bar code correctly decode PDF4 17, which is adopted by Symbol Technology Company on 1990. It is a multi-line, continuous and variable-length symbol with a large amount of data. Each bar code has 3-90 lines, and each line has a beginning part, a data part and an end part. Its character set includes all 128 characters, and the maximum data content is 1850 characters. One-dimensional bar code only expresses information in one direction (generally horizontal direction), and does not express any information in the vertical direction. Its height is usually for readers' alignment. The application of one-dimensional bar code can improve the speed of information input and reduce the error rate, but it also has some disadvantages: * The data capacity is small: about 30 characters * It can only contain letters and numbers * The bar code size is relatively large (low space utilization) * After the bar code is damaged, it is impossible to read the bar code that stores information in two-dimensional space in both horizontal and vertical directions, which is called two-dimensional bar code. Like one-dimensional bar code, two-dimensional bar code has many different coding methods, or coding systems. As far as the coding principles of these codes are concerned, they can usually be divided into the following three types: 1. Linear stacked QR code is based on the coding principle of one-dimensional bar code, which is formed by vertically stacking multiple one-dimensional codes. Typical coding systems are: Code 16K, Code49, PDF4 17, etc. 2. Matrix QR code is coded in rectangular space through the different distribution of black and white pixels in the matrix. Typical coding systems are: Aztec, MaxiCode, QRCode, DataMatrix, etc. 3. Postal codes are coded by bars with different lengths, which are mainly used for mail coding, such as Postnet and BPO4-State. Among many kinds of 2D barcodes, the commonly used coding systems are: DataMatrix, Maxicode, AZTEC, QR Code, Vericode, PDF 4 17, Ultra Code, Code 49, Code 16k, etc. Among them, *DataMatrix is mainly used to identify small parts in the electronics industry, such as the code printed on the back of Intel Pentium processors. *MaxiCode was developed by United Parcel Service Company (UPS) to sort and track parcels. *Aztec is introduced by WelchAllyn Company of the United States, and can accommodate up to 3832 numbers or 3067 alphabetic characters or 19 14 bytes of data. Next, we take PDF4 17 code as an example to introduce the characteristics and characteristics of two-dimensional code. 1) introduction to pdf 4 17 the code name pdf417 was invented by Dr. Wang, a Chinese studying in the United States. PDF is the abbreviation of English PortableDataFile, which means "portable data file". Because each symbol character that constitutes a bar code consists of four bars and four spaces, if the narrowest bar or space that constitutes a bar code is called a module, then the total number of modules of the above four bars and four spaces must be 17, so it is called 4 17 code or PDF4 17 code. 2) the characteristics of pdf 4171. The large information capacity PDF4 17 code can represent not only letters, numbers and ASCII characters, but also binary numbers. In order to make the encoding more compact and improve the information density, PDF4 17 has three formats when encoding: * The expanded alphanumeric compression format can accommodate 1850 characters; * binary /ASCII format can hold 1 108 bytes; * Digital compression format can accommodate 27 10 digits. 2. Error correction ability One-dimensional barcodes usually have the verification function to prevent misreading. Once the barcodes are defaced, they will be rejected. Two-dimensional bar code can not only prevent errors, but also correct them. Even if the bar code is partially damaged, the correct information can be recovered. 3. Ordinary printing equipment with low printing requirements can print and fax can read. 4.PDF4 17 code can be read by various reading devices, laser readers with grating and image readers with line scanning and area scanning. 5. The size can be adjusted to suit different printing spaces. 6. The coding system has become an international standard, and China has also formulated a national standard of 4 17 code. 3) Error correction function of PDF 417 The error correction function of two-dimensional barcode is realized by repeating (redundantly) some information. For example, in the PDF4 17 code, a line contains not only the information of its own line, but also some information reflecting the characters in other positions (error correction code). In this way, even when a certain part of the bar code is damaged, its information can be recovered by error correction codes existing in other places. The error correction capability of PDF4 17 is divided into 0~8***9 levels according to the number of error correction codes, as shown in Figure 4. The higher the level, the more correction codes, the stronger the correction ability and the larger the bar code. When the correction level is 8, even if the barcode is defaced by 50%, it can be read correctly. 4) Several variants of pdf 4 17 There are also several variant coding forms: *PDF4 17 truncation code In a relatively "clean" environment, the bar code is unlikely to be destroyed, so the line indicator on the right can be omitted to reduce the terminator. *PDF4 17 microcode further reduces the PDF code. * macro PDF4 17 code When the file content is too long to be represented by a PDF4 17 code, it can be represented by a macro PDF4 17 code plus multiple barcodes (1~99999). Advantages of two-dimensional code As can be seen from the above introduction, two-dimensional code has obvious advantages over one-dimensional bar code, which can be summarized as: 1) The data capacity is larger; 3) The relative size of bar code is small; 4) has the ability to resist destruction [edit this paragraph] VIII. Barcode production Barcode is usually printed or printed by a barcode printer. The biggest difference between bar code printer and ordinary printer is that the printing of bar code printer is based on heat, and carbon tape is used as printing medium (or thermal paper is directly used) to complete the printing. Using carbon ribbons of different materials can achieve high-quality printing effect and continuous high-speed printing without supervision. 1. the application software labelmxcoreldraw Photoshop illustrator labelmx belongs to professional barcode generation and printing software, which integrates barcode generation, drawing design, label making and batch print, and can print fixed and variable data. CorelDRAW, Photoshop and Illustrator all belong to professional drawing design software. In addition, Labelmx can export barcodes to vector images (. The sum of electromotive force. Wmf) interacts with CorelDRAW, Photoshop and Illustrator. [Edit this paragraph] 9. Commodity barcode: EAN- 13 general commodity barcode generally consists of prefix part, manufacturer code, commodity code and check code. The prefix code in commodity bar code is used to identify the country or region, and the code is given in ean international. For example, 00-09 stands for the United States and Canada. 45-49 stands for Japan. 690-692 stands for Chinese mainland, 47 1 stands for Taiwan Province Province and 489 stands for Hong Kong Special Administrative Region. The empowerment of manufacturers' codes is organized by article codes in various countries or regions, while in China, the National Article Coding Center gives manufacturers' codes. Commodity codes are codes used to identify commodities, and the right to assign codes is exercised by the product manufacturers themselves. Manufacturers themselves decide which Arabic numerals to use for their products according to the prescribed conditions. At last, the 1 parity code is used to check the correctness of the L- 12 digital code from the left in the barcode. Commodity barcode refers to a symbol composed of a group of regularly arranged bars, spaces and their corresponding characters, which is used to represent certain commodity information. Among them, the bar is dark and empty, which is a reading device used to scan and read bar codes. Its corresponding characters consist of a group of Arabic numerals for people to read directly or input data to the computer through the keyboard. This set of spaces and corresponding characters represent the same information. Bar code technology was born with the development and application of computer and information technology. It is a new technology integrating coding, printing, identification, data acquisition and processing. Using bar code scanning is the general trend of future market circulation. In order to make goods circulate freely and widely in the world, enterprises must abide by the relevant provisions of commodity bar codes whether designing, manufacturing, applying for registration or using commodity bar codes. At present, ENA barcode, UPC barcode, 25 barcode, cross barcode, Kudba barcode, Sanjiu barcode and 128 barcode are commonly used in the world, among which EAN barcode is the most commonly used commodity. EAN commodity bar code, also known as general commodity bar code, is formulated by ean international and is widely used in the world. It is the most widely used commodity bar code in the world. At present, this commodity bar code is being used in China. EAN commodity bar codes are divided into EAN- 13 (standard version) and EAN-8 (abbreviated version). The coding of commodity bar codes follows the principle of uniqueness, so as to ensure that commodity bar codes will not be repeated in the global scope, that is, a commodity item can only have one code, or a code can only identify one commodity item. Commodities with different specifications, different packages, different varieties, different prices and different colors can only use different commodity codes. The standard size of commodity bar code is 37.29mmx26.26mm, and the magnification is 0.8-2.0. When the printing area allows, the barcode with magnification of 1.0 should be selected to meet the reading requirements. The smaller the magnification, the higher the printing accuracy. When the printing accuracy can not meet the requirements, it is easy to read the bar code. Because the identification of bar code is realized by the color contrast between bar code and blank bar code, generally speaking, as long as the color can meet the requirements of contrast (PCS value), light color can be used as blank color, such as white, orange and yellow, and dark color as bar, such as black, dark green and dark brown. The best color scheme is black stripes and white spaces. According to the practical experience of bar code detection, red, gold and light yellow should not be used as bar code colors, and transparent and gold should not be used as blank colors. EAN-8 commodity bar code refers to the 8-digit commodity bar code used for identification, which consists of 7-digit commodity item code and 1 digit check code. The birth of commodity bar code greatly facilitates the circulation of commodities, and modern society cannot do without commodity bar code. According to statistics, at present, there are 500,000 kinds of products in China that use the international commodity bar code. After China's entry into WTO, enterprises will surely win space for activities on the international stage. To keep up with international practice and meet the needs of international trade, enterprises should not mistreat commodity bar codes. Prefix code organization/country (or region) where the application field is located Prefix code organization/country (or region) where the application field is located 000 ~ 019; 030~039; 060 ~ 139 USA 020 ~ 029; 040~049; 200 ~ 299 Store code 050 ~ 059 Coupon 300 ~ 379 France 380 Bulgaria 383 Slovenia 385 Croatia 387 Bosnia and Herzegovina 400 ~ 440 Germany 450 ~ 459; 490 ~ 499 Japan 460 ~ 469 Russia 470 Kyrgyzstan 47 1 China Taiwan Province Province 474 Estonia 475 Latvia 476 Azerbaijan 477 Lithuania 478 Uzbekistan 479 Sri Lanka 480 Philippines 48 1 Belarus 482 Ukraine 484 Moldova 485 Armenia 486 Georgia 487 Kazakhstan 489 China Hong Kong Special Administrative Region 5 00 ~ 509 Britain 520 Greece 528 Lebanon 529 Cyprus 530 Albania 530 590 Poland 594 Romania 599 Hungary 600, 60 1 South Africa 603 Ghana 608 Bahrain 609 Mauritius 6 1 Morocco 6 13 Algeria 6 16 Kenya 6 18 C? te d 'Ivoire 19 Tunisia 62 1 Syria 622 Egypt 624 Libya 625. UAE 640 ~ 649 Finland 690 ~ 695 China people * * * Republic 700 ~ 709 Norway 729 Israel 730 ~ 739 Sweden 740 Guatemala 74 1 El Salvador 742 Honduras 743 Nicaragua 744 Costa Rica 745 Panama 746 Dominica 750 Mexico 754 ~ 755 Canada 759 Venezuela 760 ~ 769 Switzerland 770 Colombia 773 Uruguay 775 Peru 777 Bolivia 779 Argentina 780 Chile 78 Paraguay 786 Ecuador 789 ~ 790 Brazil 800 Korea 869 Turkey 870 ~ 879 Netherlands 880 Korea 884 Cambodia 885 Thailand 888 Singapore 890 India 893 Vietnam 899 Indonesia 900 ~ 9 19 Austria 930 ~. 9 Australia 940 ~ 949 New Zealand 955 Malaysia 958 China Special Administrative Region 977 serial publications 978, 979 books 980 bills receivable 98 1, 982 general circulation vouchers 990 ~ 999 coupons [edit this paragraph] X. Requirements for printing bar codes The standard size of commodity bar code is 37.29mmx26.26mm, and the magnification is 0.8-2.0. When the printing area allows, the barcode with magnification of 1.0 should be selected to meet the reading requirements. The smaller the magnification, the higher the printing accuracy. When the printing accuracy can not meet the requirements, it is easy to read the bar code. Because the identification of bar code is realized by the color contrast between bar code and blank bar code, generally speaking, as long as the color can meet the requirements of contrast (PCS value), light color can be used as blank color, such as white, orange and yellow, and dark color as bar, such as black, dark green and dark brown. The best color scheme is black stripes and white spaces. According to the practical experience of bar code detection, red, gold and light yellow should not be used as bar code colors, and transparent and gold should not be used as blank colors. XI。 The meaning of commodity barcode number takes barcode 69369838000 13 as an example. This bar code is divided into four parts, from left to right: 1-3 digits: * * * 3 digits, corresponding to bar code 693, which is one of China's national codes. (690-695 are all codes of China, which are allocated internationally); 4-8 digits: * * * 5 digits, corresponding to barcode 69838, representing the manufacturer's code, which is applied by the manufacturer and allocated by the state; 9- 12 digits: * * 4 digits, corresponding to barcode 000 1, representing the commodity code in the factory, which is determined by the manufacturer; 13: * * *1,corresponding to 3 of the barcode, is a check code, which is calculated by the previous 12 bits according to a certain algorithm.