At present, ENA barcode, UPC barcode, 25 barcode, Cross barcode, Kudba barcode, 39 barcode and 128 barcode are commonly used in the world, among which EAN barcode is the most commonly used commodity.
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. Information density is an important parameter to describe bar code symbols, that is, the number of letters that may be contained 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. 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. With the development of bar code technology and the diversification of three bar code systems, the standardization of bar code 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.