Barcode tiáoxíngmǎ
Edit this paragraph 1. History of barcode
Barcode technology first emerged in the turbulent 1920s and was born in Westinghouse’s experiment room. An eccentric inventor named John Kermode "whimsically" wanted to automatically sort postal documents. At that time, every idea about the application of electronic technology was very novel.
His idea was to mark envelopes with barcodes. The information in the barcode was the address of the recipient, much like today's postal code. For this reason, Kermode invented the earliest barcode identification. The design scheme is very simple (note: this method is called the module comparison method), that is, one "bar" represents the number "1", and two "bars" represent the number "2". And so on. He then invented a barcode reading device consisting of basic components: a scanner (capable of emitting light and receiving reflected light); a method of measuring the reflected signal strips and voids, the edge positioning coil; and a device that uses the measurement results. method, the decoder.
Kermode's scanner used a then-newly invented photovoltaic cell to collect reflected light. The "empty" reflection is a strong signal, and the "bar" reflection is a weak signal. Unlike today's high-speed electronic components applications, Kermode uses magnetic coils to measure "bars" and "empties." It's like a child connecting a wire to a battery and wrapping it around a nail to clip paper. Kermode uses a coil with an iron core to attract a switch when it receives an "empty" signal, and when it receives a "bar" signal, it releases the switch and completes the circuit. As a result, the earliest barcode readers were noisy. The switch is controlled by a series of relays, and "on" and "off" are determined by the number of "strips" printed on the envelope. With this method, barcode symbols sort letters directly.
Shortly thereafter, Kermode collaborator Douglas Young made some improvements based on the Kermode code.
The amount of information contained in Kermode codes is quite low, and it is difficult to compile more than ten different codes. Young codes use fewer bars, but take advantage of changes in the size of the spaces between the bars, just like today's UPC barcode symbols that use four different bar and space sizes. The new barcode symbology can encode a hundred different regions in the same size space, while the Kermode code can only encode ten different regions.
It was not until the patent documents of 1949 that the omnidirectional barcode symbol invented by Norm Woodland and Bernard Silver was recorded for the first time. Before that, there was no record of barcode technology in the patent documents, and there was no A precedent for practical application. Norm Woodland and Bemard Silver's idea was to take the vertical "bars" and "voids" of Kermode and YOung and bend them into a ring, much like an archery target. In this way, the scanner can decode the barcode symbol by scanning the center of the pattern, regardless of the direction of the barcode symbol.
In the process of continuously improving it using this patented technology, a science fiction writer Isaac-Azimov in his book "The Naked Sun" tells about the implementation of new methods using information encoding Examples of automatic recognition. At the time, people thought the barcode symbology in this book looked like a checkerboard with square tiles, but today's barcode professionals will immediately realize that it is a two-dimensional matrix barcode symbology. Although this barcode symbol has no orientation, positioning or timing, it is clear that it represents a high information density digital encoding.
It wasn’t until 1970, when Iterface Mechanisms developed the “QR code”, that there were printing and reading equipment for two-dimensional matrix barcodes that were affordable for sale. At that time, two-dimensional matrix barcodes were used to automate the typesetting process in newspapers. Two-dimensional matrix barcodes are printed on paper tape and scanned and read by today's one-dimensional CCD scanners. The light from the CCD shines on the paper tape, and each photocell is aimed at a different area of ??the paper tape. Each photocell outputs a different pattern depending on whether the barcode is printed on the paper tape, and the combination produces a high-density information pattern. In this way a single character can be printed in the same size space as a single bar in early Kermode codes. Timing information is also included, so the whole process is reasonable. When the first systems hit the market, the complete set of equipment, including printing and reading equipment, cost approximately $5,000.
Shortly thereafter, with the continuous development of LEDs (light-emitting diodes), microprocessors and laser diodes, there was an explosion of new identification symbols (symbolism) and their applications, which people called "Barcode Industry". It is rare to find a company or individual today who has not been directly exposed to fast and accurate barcoding technology. Due to the rapid technological progress and development in this field, and more and more application fields are being developed every day, it will not be long before bar codes are as popular as light bulbs and semiconductor radios, and will make every one of our lives All become easier and more convenient.
Edit this paragraph 2. Principle of barcode recognition
To convert barcodes compiled according to certain rules into meaningful information, you need to go through two processes: scanning and decoding. The color of an object is determined by the type of reflected light. White objects can reflect visible light of various wavelengths, while black objects absorb visible light of various wavelengths. Therefore, when the light emitted by the barcode scanner light source is reflected on the barcode, the reflected light The light is irradiated onto the photoelectric converter inside the barcode scanner, and the photoelectric converter converts the reflected light signals of different strengths into corresponding electrical signals. According to differences in principles, scanners can be divided into three types: light pen, CCD, and laser. The electrical signal is output to the amplifier 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 width of the white bars and black bars is different, and the duration of the corresponding electrical signals is also different. The decoder then determines the number of bars and spaces by measuring the number of 0 and 1 pulse digital electrical signals. The width of bars and spaces is determined by measuring the duration of the 0,1 signal. The data obtained at this time is still messy. To know the information contained in the barcode, you need to replace the barcode with the corresponding numbers and character information according to the corresponding encoding rules (for example: EAN-8 code). Finally, the detailed information of the item is identified through data processing and management by a computer system.
Edit this paragraph 3. Advantages of barcodes
1. Strong reliability. Barcode reading accuracy far exceeds manual recording, with an average of one error occurring every 15,000 characters.
2. High efficiency. Barcodes can be read very quickly, equivalent to 40 characters per second.
3. Low cost. Compared with other automated identification technologies, barcode technology only requires a small sticker and a relatively simple optical scanner, and the cost is quite low.
4. Easy to make. The writing of barcodes is very simple, and production only requires printing. It is called a "printable computer language".
5. Easy to operate. The barcode recognition equipment has a simple structure and is easy to use.
6. Flexible and practical. Barcode symbols can be entered manually on the keyboard, or they can be combined with relevant equipment to form an identification system to achieve automated identification, or they can be linked to other control equipment to achieve automated management of the entire system.
Edit this paragraph 4. Scanning of barcodes
Scanning of barcodes requires a scanner. The scanner uses its own light source to illuminate the barcode, and then uses a photoelectric converter to receive the reflected light and convert the reflected light. The light and dark are converted into digital signals. No matter what rules are used to print the barcode, it is composed of a quiet zone, a start character, a data character and a stop character. Some barcodes also have check characters between the data characters and the terminating character.
▲Quiet zone: As the name suggests, it is an area that does not carry any information and serves as a reminder.
▲Start character: The first character has a special structure. When the scanner reads this character, it begins to officially read the code.
▲Data characters: the main content of the barcode.
▲Check character: Verify whether the read data is correct. Different encoding rules may have different verification rules.
▲Terminator character: The last character also has a special structure and is used to inform that the code scanning is completed. It also plays the role of verification calculation.
In order to facilitate bidirectional scanning, the starting and ending characters have an asymmetric structure. Therefore, the scanner can automatically rearrange the barcode information when scanning. There are three types of barcode scanners: light pen, CCD, and laser
▲Light pen: The most primitive scanning method requires manual movement of the light pen and contact with the barcode.
▲CCD: A scanner that uses CCD as a photoelectric converter and LED as a light source. Within a certain range, automatic scanning can be achieved. And it can read barcodes on various materials and uneven surfaces, and the cost is relatively low. However, compared with the laser type, the scanning distance is shorter.
▲Laser: A scanner that uses laser as a light source. It can be divided into linear type, full angle type, etc.
Line type: mostly used in handheld scanners, with long range and high accuracy.
Full angle: mostly horizontal, with high degree of automation, and can automatically read barcodes in various directions.
Edit this paragraph 5. Advantages of barcode technology
Barcode is by far the most economical and practical automatic identification technology. Barcode technology has the following advantages
A. Fast input speed: Compared with keyboard input, barcode input is 5 times faster and can achieve "instant data input".
B. High reliability: the error rate of keyboard input data is one in three hundred, the error rate of using optical character recognition technology is one in ten thousand, and the error rate of using bar code technology is less than one in a million.
C. Large amount of information collected: Traditional one-dimensional barcodes can collect information of dozens of characters at a time, while two-dimensional barcodes can carry information of thousands of characters and have certain automatic error correction capabilities.
D. Flexible and practical: Barcode identification can be used alone as a means of identification, or it can be formed into a system with related identification equipment to achieve automatic identification, and it can also be connected with other control equipment to achieve automated management.
In addition, barcode labels are easy to produce and have no special requirements for equipment and materials. The identification equipment is easy to operate and does not require special training, and the equipment is relatively cheap.
Edit this paragraph 6. Barcode encoding rules
Uniqueness: The same product with the same specifications corresponds to the same product code, and the same product with different specifications corresponds to different product codes. Different product codes are assigned according to the different properties of the product, such as weight, packaging, specifications, smell, color, shape, etc.
Permanent: Once the product code is assigned, it will not be changed and is lifelong. When such a product is no longer produced, its corresponding product code can only be put on hold and cannot be reused or allocated to other products.
No meaning: In order to ensure that the code has enough capacity to adapt to the needs of frequent product updates, it is best to use meaningless sequence codes.
Edit this paragraph 7. Differences in barcode coding systems
UPC: (Unified Product Code)
Can only represent numbers A, B, C, and D , E four versions version A - 12 digit version E - 7 digits, the last digit is the check digit, the size is 1.5" wide and 1" high, and the background must be clear. Mainly used in the United States and Canada, for industrial, Pharmaceutical, warehouse and other departments. When UPC is decoded as twelve digits, the definition is as follows: First digit = numeric identifier (as established by the UCC (Uniform Code Committee)). Digits 2-6 = Manufacturer's identification number (including the first digit). 7-11 = The 12th digit of the unique manufacturer product code = check digit (used for error detection)
Code 3 of 9:
Can represent letters, numbers and other symbols ***43 characters: A -Z, 0 - 9, -.$/+%, the length of the pace barcode is variable, usually "*" is used as the start and terminator, and the check code does not require code density. At 3 - 9.4 characters per inch, the blank area is 10 times that of the narrow strip. It is used in industry, books, and ticket automation management.
Code 128:
Represents high-density data, the string is variable length, and the symbol contains a check code. There are three different versions: A, B, and C. 128 characters are available. In three string sets A, B, or C respectively, used for industry, warehouse, retail and wholesale.
Interleaved 2-of-5 (I2 of 5):
Can only represent numbers 0-9, variable length, continuous barcode, all bars and spaces represent codes, no. One number starts with a bar, and the second number consists of an empty space. The blank area is 10 times wider than the narrow bar. It is used in commodity wholesale, warehouses, airports, production/packaging identification, and industry. The barcode reading rate is high and can be applied to Fixed scanners reliably scan the highest density of all 1D barcodes.
Codabar (Cudabar barcode):
Can represent numbers 0 - 9, characters $, +, -, and a, which can only be used as a start/terminator. b, c d four characters, variable length, no check digit, used in material management, libraries, blood stations and current airport parcel delivery, the blank area is 10 wider than the narrow bar, non-continuous barcode, each character Expressed as 4 bars and 3 empty.
PDF417 (QR code):
Multi-line barcode does not need to be connected to a database and can store a large amount of data. It is used in: hospitals, driver's licenses, material management, During cargo transportation, when the barcode is damaged to a certain extent, error correction can enable the barcode to be correctly decoded. PDF417 is a product developed by Symbol Technology Company in 1990. It is a multi-line, continuous, variable-length symbolic identifier that contains a large amount of data. Each barcode has 3-90 lines, and each line has a start part, data part, and end part. Its character set includes all 128 characters, and the maximum data content is 1850 characters.
One-dimensional barcodes only express information in one direction (usually the horizontal direction), but do not express any information in the vertical direction. Their certain height is usually to facilitate the alignment of the reader.
The application of one-dimensional barcodes can increase the speed of information entry and reduce the error rate, but one-dimensional barcodes also have some shortcomings:
* Small data capacity: 30 characters Left and right
* Can only contain letters and numbers
* Barcode size is relatively large (low space utilization)
* Barcode cannot be used after it is damaged Read
Bar codes that store information in two-dimensional spaces in the horizontal and vertical directions are called 2-dimensional bar codes.
Like one-dimensional barcodes, two-dimensional barcodes also have many different encoding methods, or coding systems. In terms of the coding principles of these code systems, they can usually be divided into the following three types
1. Linear stacked QR code
It is based on the coding principle of one-dimensional barcodes , produced by stacking multiple one-dimensional codes vertically.
Typical code systems include: Code 16K, Code 49, PDF417, etc.
2. Matrix QR code
It is encoded in a rectangular space through the different distribution of black and white pixels in the matrix. Typical code systems include: Aztec, Maxi Code, QR Code, Data Matrix, etc.
3. Postal code
Encoding through bars of different lengths, mainly used for mail encoding, such as: Postnet, BPO 4-State.
Among many types of two-dimensional barcodes, commonly used code systems include: Data Matrix, Maxi Code, Aztec, QR Code, Vericode, PDF417, Ultracode, Code 49, Code 16K, etc., among which:
p>
* Data Matrix is ??mainly used for marking small parts in the electronics industry. For example, this code is printed on the back of Intel's Pentium processor.
* Maxi Code was developed by the United Parcel Service (UPS) and is used for parcel sorting and tracking.
* Aztec is launched by the American Welch Allyn Company and can accommodate up to 3832 numbers or 3067 alphabetic characters or 1914 bytes of data.
Below, we take the PDF417 code as an example to introduce the characteristics and characteristics of the two-dimensional barcode.
1) Introduction to PDF417
The PDF417 code was invented by Dr. Wang Yinjing (sound), a Chinese in the United States. PDF is the abbreviation of the three words Portable Data File in English, which means "portable data file". Because each symbol character that makes up a barcode is composed of 4 bars and 4 spaces, if the narrowest bar or space that makes up the barcode is called a module, then the total number of modules of the above 4 bars and 4 spaces is one. It is set as 17, so it is called 417 code or PDF417 code.
2) Characteristics of PDF417
1. Large information capacity
In addition to letters, numbers, and ASCII characters, PDF417 codes can also express binary numbers. In order to make the encoding more compact and increase the information density, PDF417 has three formats when encoding:
* Extended alphanumeric compression format can accommodate 1850 characters;
* Binary/ASCII format Can hold 1108 bytes;
* Digital compressed format can hold 2710 numbers.
2. Error correction ability
One-dimensional barcodes usually have a verification function to prevent misreading. Once the barcode is defaced, it will be rejected. The two-dimensional barcode can not only prevent errors, but also correct them. Even if the barcode is partially damaged, the correct information can be restored.
3. Printing requirements are not high
Ordinary printing equipment can print, and faxes can also be read.
4. Can be read with a variety of reading devices
PDF417 code can be read with laser readers with rasters, linear and area scanning image readers.
5. The size is adjustable to adapt to different printing spaces
6. The disclosure of code system has formed an international standard, and our country has also formulated the national standard of 417 codes.
3) Error correction function of PDF417
The error correction function of 2D barcode is achieved by repeatedly representing part of the information (redundancy). For example, in the PDF417 code, in addition to the information of this line, a certain line also contains information that reflects characters (error correction codes) in other positions. In this way, even when part of the barcode is damaged, its information can be restored through error correction codes that exist elsewhere.
The error correction ability of PDF417 is divided into 0~8***9 levels according to the number of error correction code words. See Figure 4. The higher the level, the more correction code words and the stronger the correction ability. Barcode Also bigger. When the correction level is 8, the barcode can be read correctly even if it is 50% stained.
4) Several deformations of PDF417
PDF417 also has several deformed coding forms:
* PDF417 truncation code
In relatively "clean" environments where the likelihood of barcode damage is small, the line indicator on the right can be omitted and the terminators reduced.
* PDF417 microcode
Further reduced PDF code.
* Macro PDF417 code
When the file content is too long to be represented by one PDF417 code, a macro PDF417 code containing multiple (1~99999) barcode blocks can be used. express.
Advantages of two-dimensional barcodes
As can be seen from the above introduction, two-dimensional barcodes have obvious advantages compared with one-dimensional barcodes, which can be summarized in the following aspects:
1) Larger data capacity
2) Beyond the limitations of alphanumeric characters
3) The relative size of barcodes is small
4) Anti-damage ability
Edit this paragraph 8. Barcode production
1. Application software
Label mx
CorelDRAW
Photoshop
Illustrator
Label mx is a professional barcode generation and printing software that integrates barcode generation, drawing design, label production, and batch printing. It can print fixed and removable To change data, CorelDRAW, Photoshop, and Illustrator are professional drawing and design software. In addition, Label mx can export barcodes as vector images (.emf and .wmf) and use them interactively with CorelDRAW, Photoshop, and Illustrator.
2. Application software
EAN-13 universal product barcode generally consists of a prefix part, manufacturer code, product code and check code. The prefix code in the product barcode is a code used to identify the country or region. The coding authority is in the International Article Numbering Association, such as 00-09 representing the United States and Canada. 45-49 represents Japan. 690-692 represents mainland China, 471 represents Taiwan, and 489 represents Hong Kong SAR. The manufacturer's code is assigned to the article coding organization of each country or region. In my country, the manufacturer's code is assigned by the National Article Coding Center. Commodity codes are codes used to identify commodities. The right to assign codes is exercised by product manufacturers themselves. Manufacturers decide which Arabic numerals to use as product barcodes on their own products according to prescribed conditions. The product barcode finally uses a 1-digit check code to verify the correctness of the 1-12th digit code from the left in the product barcode.
Full text:
Commodity barcode refers to a symbol composed of a set of regularly arranged bars, spaces and corresponding characters, which is used to represent certain product information. The bars are dark and the spaces are dark, which are used for scanning and reading with barcode reading equipment. The corresponding characters consist of a set of Arabic numerals for people to read directly or input data into the computer through the keyboard. The information represented by this group of spaces and the corresponding characters is the same.
Bar code technology was born with the development and application of computers and information technology. It is a new technology that integrates coding, printing, identification, data collection and processing.
The use of barcode scanning is a major trend in market circulation in the future. In order to enable goods to circulate freely and widely around the world, companies must abide by the relevant regulations on product barcode management, whether designing and producing, applying for registration or using product barcodes.
The commonly used code systems in the world include ENA barcode, UPC barcode, 25 barcode, crossed 25 barcode, Kudba barcode, 39 barcode and 128 barcode, etc., and the most commonly used barcode on goods is It is the EAN product barcode.
The EAN commodity bar code, also known as the universal commodity bar code, was developed by the International Article Numbering Association and is used all over the world. It is currently the most widely used commodity bar code in the world. Our country is currently promoting the use of this kind of commodity barcode in the country. EAN product barcodes are divided into two types: EAN-13 (standard version) and EAN-8 (shortened version).
EAN-13 universal product barcode generally consists of a prefix part, manufacturer code, product code and check code. The prefix code in the product barcode is a code used to identify the country or region. The coding authority is in the International Article Numbering Association, such as 00-09 representing the United States and Canada. 45-49 represents Japan. 690-692 represents mainland China, 471 represents Taiwan, and 489 represents Hong Kong SAR. The manufacturer's code is assigned to the article coding organization of each country or region. In my country, the manufacturer's code is assigned by the National Article Coding Center. Commodity codes are codes used to identify commodities. The right to assign codes is exercised by product manufacturers themselves. Manufacturers decide which Arabic numerals to use as product barcodes on their own products according to prescribed conditions. The product barcode finally uses a 1-digit check code to verify the correctness of the 1-12th digit code from the left in the product barcode.
The encoding of product barcodes follows the principle of uniqueness to ensure that product barcodes are not repeated worldwide, that is, one product item can only have one code, or one code can only identify one product item. Products of different specifications, different packaging, different varieties, different prices, and different colors can only use different product codes.
The standard size of product barcodes is 37.29mmx26.26mm, and the magnification is 0.8-2.0. When the printing area allows, a barcode with a magnification of 1.0 or above should be selected to meet the reading requirements. The smaller the magnification of the barcode, the higher the printing accuracy requirement. When the printing accuracy cannot meet the requirements, it is easy to cause difficulty in reading the barcode.
Since the reading of barcodes is achieved through the color contrast of the barcode bar and space, in general, as long as the color can meet the contrast (PCS value) requirements, it can be used. Usually, light colors are used for hollows, such as white, orange, yellow, etc., and dark colors are used for strips, such as black, dark green, dark brown, etc. The best color combination is black bars and white space. According to practical experience in barcode detection, red, gold, and light yellow are not suitable colors for bars, and transparent and gold cannot be used as blank colors.
EAN-8 product barcode refers to an 8-digit product barcode used for identification, which is composed of a 7-digit product item code and a 1-digit check character.
The birth of commodity barcodes has greatly facilitated the circulation of commodities, and modern society is inseparable from commodity barcodes. According to statistics, currently 500,000 products in my country use internationally accepted commodity barcodes. After my country joins the WTO, enterprises will surely gain more space for activities on the international stage. In order to be in line with international practices and adapt to the needs of international economic and trade, enterprises cannot wait for product barcodes.
Barcode prefix codes of some countries and regions (EAM) members
United States, Canada 00-09 Israel 729 Denmark 57
(In-store code) 20-29 Venezuela 759 Norway 70
Japan 45-49 Uruguay 773 Switzerland 76
Belgium/Luxembourg 54 Bolivia 773 Spain 84
Finland 64 Chile 780 Austria 90-91
p>Sweden 73 Ecuador 786 New Zealand 94
Italy 80-83 Cuba 850 Slovenia 383
Netherlands 87 Czech Republic 859 Germany 400-440
Australia 93 South Korea 880 Taiwan 471
Bulgaria 380 Singapore 888 Latvia 475
Croatia 385 Malaysia 893 Sri Lanka 479
Russia 460-469 Vietnam 977 Hong Kong 489
< p>Estonia 474 Mexico 750 Cyprus 529Lithuania 477 Colombia 770 Malta 535
Philippines 480 Peru 775 Portugal 560
Greece 520 Argentina 779 Poland 590
Macedonia 531 Paraguay 784 Hungary 599
Ireland 539 Brazil 789 Mauritius 609
Iceland 569 Slovakia 858 Albania 613
Romania 594 Yugoslavia 860 Mainland China 690 -692
Sino-foreign joint venture 693
South Africa 600-601 Thailand 885 France 30-37
Morocco 611 India 890 United Kingdom 50
Turkey 619, 869 Indonesia 899
Edit this section 9. Requirements for printing and producing barcodes
The standard size of product barcodes is 37.29mm x 26.26mm, and the magnification is 0.8-2.0. When the printing area allows, a barcode with a magnification of 1.0 or above should be selected to meet the reading requirements. The smaller the magnification of the barcode, the higher the printing accuracy requirement. When the printing accuracy cannot meet the requirements, it is easy to cause difficulty in reading the barcode.
Since the reading of barcodes is achieved through the color contrast of the barcode bar and space, in general, as long as the color can meet the contrast (PCS value) requirements, it can be used. Usually, light colors are used for hollows, such as white, orange, yellow, etc., and dark colors are used for strips, such as black, dark green, dark brown, etc. The best color combination is black bars and white space. According to practical experience in barcode detection, red, gold, and light yellow are not suitable colors for bars, and transparent and gold cannot be used as blank colors.