Barcode characters: a number of bars and blanks that represent a character. Bar: The part of the bar code that has low reflectivity to light, usually black. Empty: the part of the barcode with high reflectivity to light, usually white. Blank area: to ensure the normal reading of the barcode and retained at both ends of the barcode with the same color as the empty area of the start character: located in the barcode start position, indicating the beginning of the barcode of a special barcode characters. Terminator: A special barcode character located at the end of the barcode. Check Digit: A barcode character used to check the accuracy of the barcode, which is generated according to the character information expressed in the barcode according to certain checking rules, usually located before the terminator. Module: A width range of the same color in a barcode character. A unit consists of one or more modules. Module: the most basic unit of the barcode.
Three Nine Code
Three Nine Code is a barcode introduced by Intermec in 1975, which can represent numbers, English letters and "-", "." , "/", "+", "%", "$", " " (space) and "*" **** 44 symbols, of which "*" only as the beginning and ending characters. Sanjiu code and have simple coding rules, low BER, can represent the number of characters and other characteristics, so in various fields has a very wide range of applications. China has also formulated the corresponding national standard (GB12908-91). Three nine code only two unit width - respectively, wide unit and narrow unit. The width of the wide unit which width for the narrow unit of 1 to 3 times, generally choose 2 times, 2.5 times or 3 times. Three nine code of each barcode character consists of nine units, of which there are three wide unit, the rest is a narrow unit, so it is called three nine code.
Goods barcode (EAN, UPC code)
Commerce is the earliest field to apply barcode technology. In the commercial automation system, commodity bar code is the key. In the national standard GB/T 12904, commodity barcode (barcode for commodity) is defined as a modular combination of barcodes used to identify the international common commodity code. 1970 U.S. Supermarkets Commission developed a universal commodity code UPC code, the U.S. Uniform Code Council (UCC) and the establishment of the UPC barcode system in 1973 and the full realization of the code system standardization. Comprehensive realization of the standardization of the code system. UPC barcode successfully used in the commercial circulation area, the application and popularity of the bar code has played a great role in promoting the use of the UPC code has successfully prompted the creation of the European Association of Numerical Coding Systems (EAN). By 1981, EAN had evolved into an international organization and the EAN code was compatible with the UPC code.The EAN/UPC code is used as a consumer unit code to uniquely identify a commodity on a global scale.There are two versions of the EAN code - the standard version and the shortened version. The standard version represents 13 digits and is also known as EAN13 code, while the shortened version represents 8 digits and is also known as EAN8. The last digit of both barcodes is a check digit, which is calculated from the previous 12 or 7 digits. The two versions of the code can be referred to the national standard GB-12094-1998. EAN code consists of prefix code, vendor identification code, commodity item code and check digit. The prefix code is the code of the international EAN organization to identify each member organization, which is 690, 691 and 692 in our country; the vendor code is the code assigned to the vendor by the EAN coding organization on the basis of the prefix code assigned by EAN; the commodity item code is coded by the vendor; the check code is for the purpose of checking the correctness of the code. When compiling the commodity item code, manufacturers must comply with the basic principles of commodity coding: the same commodity item code must be compiled for the same commodity item; different commodity items must be compiled for different commodity item codes. Ensure that the commodity item and its identification code one-to-one correspondence, that is, a commodity item only a code, a code only identifies a commodity item. For example, the bar code of the listening package of Jianlibao beverage is 6901010101098, of which 690 represents our EAN organization, 1010 represents Guangdong Jianlibao Company, and 10109 is the commodity code of the listening package of the beverage. Such a code ensures that no matter when and where, 6901010101098 is unique to the goods. In addition, books and periodicals as special commodities also adopt EAN13 to indicate ISBN and ISSN. 977 prefix is used for ISSN of periodicals, and 978 is used as the prefix for ISBN of books, and our country is assigned to use the ISBN number beginning with 7, so all the barcodes on the books published by our publishers are beginning with 9787.
CODE 93 code
Code 93 code and 39 code has the same character set, but its density is higher than 39 code, so in the case of insufficient area, you can use 93 code instead of 39 code.
CODEBAR code
CodeBar code is a kind of barcode widely used in medical and book fields, its character set is 0 to 910 numbers, "ABCD" four letters and "$-:/. +" six special characters, where "ABCD" is used only as a start and stop character, and can be combined in any way.
CODE 128 code
Code 128 code can represent from ASCII 0 to ASCII 127 ***128 characters, so it is called 128 code. Code 128 code and Code 39
code have a lot of similarity, are widely used in internal management, production process, logistics control system. The difference between Code 128 and Code 39 is that Code 128 is much more similar to Code 39 than Code 39. The difference is that Code 128 can represent more characters than Code 39, and has a higher coding density per unit length. When Code 39 cannot be accommodated per unit length, or when the encoded characters exceed the limitations of Code 39, then Code 128 can be selected for encoding. So Code 128 is more flexible than Code 39.
MATRIX 25 code
Matrix 25 code can only represent the number 0 to 9.
INTERLEAVED 25 code
Interleaved 25 code is a kind of bar and empty are expressed in the information of the bar code, the interleaved 25 code has two kinds of unit widths, each bar code character consists of five units, two of which are wide units, three narrow units. Each barcode character consists of five cells, two wide cells and three narrow cells. In an interpolated 25 code symbol, the number of characters that make up the bar code symbol is even, when the characters are odd, they should be complemented with 0 on the left side to become even. Bar code characters from left to right, the odd position characters with the bar, the even position characters with the empty representation. The character set of the interspersed 25 code includes the numbers 0 to 9.
PDF417 2D Barcode
The amount of data represented by the 1D barcode is limited and does not have error correction, while the 2D barcode makes up for this deficiency. 2D barcodes have just been developed in recent years and are being used in a variety of applications. We see in the Pentium processor shell of a photolithography of a small square is the Data Matrix two-dimensional bar code. PDF417 two-dimensional bar code is a stacked two-dimensional bar code, is currently the most widely used. PDF417 bar code was invented by the United States SYMBOL company, PDF (Portable Data File) means "Portable Data File". Portable Data File". Composition of the bar code of each bar code characters by four bars and four empty **** 17 modules, so called PDF417 bar code.
PDF417 barcodes can represent numeric, alphabetic, or binary data, as well as Chinese characters. A PDF417 barcode can hold up to 1850 characters or 1108 bytes of binary data, or 2710 digits if it only represents numbers. PDF417's error-correction capability is divided into 9 levels, the higher the level, the stronger the corrective capability. Because of this error correction function, so that the defacement of the 417 bar code can also be read correctly. China has developed the national standard of PDF417 code. PDF417 barcode needs to have 417 decoding function of the barcode reader to recognize, at present, this kind of reader has a few thousands of yuan of products. PDF417 barcode's biggest advantage lies in its huge data capacity and very strong error correction ability.
QR code 2D barcode
QR Code code is a matrix two-dimensional code symbol developed by Japan Denso in September 1994, it has a one-dimensional barcode and other two-dimensional barcodes have a large capacity of information, high reliability, and can be expressed in Chinese characters and images of a wide range of textual information, confidentiality and anti-counterfeiting, etc., it also has the following main features:< /p>
Code System
The code system has been used to identify the barcode reader. /p>
Code system QR CodeData MartixPDF 417 development company Denso Corp.I.D. Matrix Inc.Symbol Technolgies Inc (Japan) (U.S.A.) (U.S.A.) code system classification matrix stacked reading speed 30 / per second 2 ~ 3 / second 3 / second reading direction of the full range ( 360 °) ± 10 ° reading method dark / light color module discrimination bar space width size discrimination Chinese characters represent 13bit16bit16bit* Each symbol represents 100 characters of information. Ultra-high-speed reading:
From the English name of the QR Code code Quick Response Code can be seen, ultra-high-speed reading characteristics of the QR Code code is different from the four-one-seven bar code, Data Matrix and other two-dimensional code of the main characteristics. Because in the CCD reads the QR Code code, the whole QR Code code symbol in the information reading is through the QR Code code symbol position detection graphic, with the hardware to realize, therefore, the information reads the process of the time required is very short, it has the ultra-high-speed reading characteristics. With CCD two-dimensional bar code reading equipment, can read 30 QR Code symbols containing 100 characters per second; for the same data information containing the four-one-seven bar code symbols, only 3 symbols per second; for Data Martix matrix code, only 2 to 3 symbols per second can be read. QR Code Code's ultra-high-speed reading characteristics is that it can be widely used in industrial automation The QR Code's ultra-fast readability allows it to be used in a wide range of industrial automation applications such as production line management. Omni-directional reading:
QR Code has omni-directional (360°) reading characteristics, which is QR Code code is better than rows of 2D barcodes such as four-seven barcodes, another main feature, due to the four-seven barcode is a one-dimensional barcode symbols in the height of the row of the truncation of the realization, so it is difficult to realize the omni-directional reading, and the azimuth angle of its reading is only ± 10°. It can effectively represent Chinese and Japanese characters:
Because QR Code uses a specific data compression mode to represent Chinese and Japanese characters, it only uses 13bit to represent a Chinese character, whereas 2D codes such as 417 barcode and Data Martix do not have a specific Chinese character representation mode, and therefore only use the byte representation mode to represent Chinese characters, and 16bit is required when representing Chinese characters in the byte mode. When using byte mode to represent Chinese characters, 16 bits (two bytes) are needed to represent a Chinese character, so QR Code is 20% more efficient than other 2D barcodes in representing Chinese characters. Coded Character Set:
1, numeric data (digits 0 to 9);
2, alphanumeric data (digits 0 to 9; capital letters A to Z; 9 other characters: space , $, %, *, +, -, . , /, :);
3, 8-bit byte-type data;
4, Japanese kanji characters;
5, Chinese kanji characters (kanji and non-kanji characters corresponding to GB 2312).
Basic Characteristics of QR Code Symbols Symbol Specifications 21×21 Module (Version 1) - 177×177 Module (Version 40) (Each specification: 4 additional modules on each side) Data Type and Capacity - Numeric Data :7,089 characters - Alphanumeric Data :4,296 characters (refers to the maximum specification symbol version 40-L level) - 8-bit Byte Data :2,. 953 characters - Chinese kanji and Japanese kanji data :1,817 characters Data representation method Dark-colored modules represent binary "1" and light-colored modules represent binary "0". Error correction capability - Class L: Error correction of about 7% of data characters - Class M: Error correction of about 15% of data characters - Class Q: Error correction of about 25% of data characters - Class H: Error correction of about 30% of data characters Structural linking (optional) A set of information masks can be represented by 1-16 QR Code symbols (intrinsic), which allows a ratio of dark-colored modules to light-colored modules in the symbols to be close to 1:1, thus making it possible to avoid the problem of difficulty in decoding due to the arrangement of neighboring modules. This minimizes the possibility of difficulties in decoding due to the arrangement of adjacent modules. Expanded Interpretation (optional) This approach allows the symbol to represent data outside the default character set (e.g., Arabic characters, Old Slavic characters, Greek letters, etc.), as well as other interpretations (e.g., data represented in a certain compression) or encoding the needs of industry characteristics. Independent positioning function has QR Code code can be efficiently expressed in Chinese characters, the same content, its size is smaller than the same density of PDF417 barcode. Most of the bar code printers on the market today support QR code bar code, its proprietary Chinese character mode is more suitable for our application. Therefore, QR code has a good application prospect in China.