E-mail:
land@szhw-tech.comCall Us:
+8613148715508
Barcodes originated in the 1940s, were used in the 1970s, and became popular in the 1980s. Bar code technology is an automatic identification technology that is produced and developed in computer application and practice and is widely used in commerce, postal service, library management, warehousing, industrial production process control, transportation and other fields. The advantages of low cost and strong reliability occupy an important position in today's automatic identification technology.
A barcode is a mark consisting of a group of regularly arranged bars, spaces and corresponding characters. "Bar" refers to the part with low reflectivity to light, and "space" refers to the part with high reflectivity to light.These bars and spaces are composed of the data expresses certain information, and can be read by a specific device and converted into binary and decimal information compatible with computers. Usually for each item, its code is unique. For ordinary one-dimensional barcodes, the corresponding relationship between the barcode and the commodity information must be established through the database. When the barcode data is transmitted to the computer, the computer applications operate and process data. Therefore, the ordinary one-dimensional barcode is only used as identification information in the process of use, and its meaning is realized by extracting the corresponding information in the database of the computer system. One-dimensional barcodes are simple to make, and the coding system is easier to obtain and forge by criminals. Second, it is almost impossible for one-dimensional barcodes to represent Chinese characters and image information.
One-dimensional bar code refers to the arrangement rules of bar code bars and spaces. It only expresses information in one direction (usually the horizontal direction), but does not express any information in the vertical direction. Its certain height is usually to facilitate the alignment of the reader. Commonly used one-dimensional code systems include: EAN barcode, UPC barcode, EAN 128 barcode, Code 39 barcode, Code 93 barcode, Interleaved 2 of 5 barcode, Codabar barcode, etc.
Common symbology
1. EAN barcode
It is an international symbol system. It is a barcode with a fixed length and no meaning. The information expressed is all numbers, and it is mainly used for commodity identification. A barcode symbol consists of a series of parallel bars and spaces surrounded by blank space.
(1) EAN barcode character set includes A subset, B subset and C subset. Each barcode symbol consists of 2 bars and 2 spaces. Each bar and space consists of 1-4 modules, and the total number of modules per barcode character is 7. The barcode character set can represent a total of 10 numeric characters from 0 to 9.
(2) In addition to the barcode symbols representing numbers, there are also some auxiliary barcode characters, which are used as the delimiter to represent the start, the end, and the middle separator of the bisected barcode symbol.
2.UPC barcode
UPC barcode is a code system developed by the United States Uniform Code Committee (UCC), with UPC-A and UPC-E barcodes.
(1) UPC-A consists of 12 digits. UPC-A barcodes are compatible with EAN-13 barcodes prefixed with "0".
(2) UPC-E is composed of 8 digits, which is obtained by compressing the UPC-A code whose system character is 0 by eliminating zero. Codes are only allowed if the item is too small to print to represent UPC-A.
3. EAN 128 barcode
In order to further express the relevant information of the commodity, it is sometimes necessary to add supplementary codes to the EAN and UPC codes. The supplementary codes are represented by UCC/EAN-128 barcode symbols (referred to as EAN-128). EAN-128 barcode is the only barcode symbol that can represent EAN, UPC standard supplementary code. It is a continuous, non-fixed-length, meaningful high-density code.
4. Code 39 barcode
The Code 39 barcode is a barcode launched by intermec in 1975, which can encode 44 characters such as numbers and English letters. Because it has the advantages of low bit error rate and many characters, it is widely used in the fields of automobile industry, economic management, medical and health care, postal service, storage and transportation unit and so on.
The Code 39 bar code has only two unit widths, and each bar code character is composed of 9 units, of which 3 are wide units and the rest are narrow units. Because the three-nine bar code is composed of five bars and four spaces, it has a bar code bar code symbol interval, so it is a non-continuous bar code. The design of the 39 barcode has a strong self-checking function, so the probability of substitution error is very small. Its highest density is 40 / (25.4mm).
5.Code 93 barcode
It is a barcode similar to Code 39 yards, it has a higher density and can replace Code 39 yards.
Introduced in 1982, the Code 93 barcode is a very dense barcode symbology. The Code 39 barcode has many advantages, but its density is not very high, which is determined by its coding method. Therefore, in some cases where the Code 39 barcode is used, there is a problem of insufficient printing area. The design of the Code 93 barcode is to solve this problem. question. The Code 93 barcode is compatible with the Code 39 barcode, mainly in that they have the same data character set.
Ninety-three barcodes are coded by module combination method. Each barcode character of ninety-three barcodes consists of 9 modules, including three bars and three spaces, and each bar or space consists of 1, 2, 3 or 4 modules. The encoding capacity of Jiu San barcode is 56, and 48 combinations are selected. It has no self-checking function. In order to ensure data security, double check characters are used, and its reliability is higher than that of the 39 barcode.
6. Interleaved 2 of 5 barcode
The Interleaved 2 of 5 barcode was invented by the American company intermec in 1972. It was initially used in the field of warehousing and heavy industry, and was used for the identification and management of storage and transportation units after standardization.
Interleaved 2 of 5 barcode is a barcode in which both bars and spaces represent information. There are only two unit widths in an Interleaved 2 of 5 barcode symbol. Each barcode data symbol is composed of 5 units, two of which are Wide cells (represented by binary "1"), two are narrow cells (represented by binary "0"). In an Interleaved 2 of 5 barcode symbol, all wide cells are equal, all narrow cells are equal, and the bar (empty) ratio is generally controlled between 2.00-3.00.
The Interleaved 2 of 5 barcode is a high-density barcode with a maximum density of 17.70/(25.4mm). The existence of a printing defect in the Interleaved 2 of 5 barcode will not cause a substitution error, it has a self-checking function barcode. Because the barcode symbol can be successfully read from both directions, it is a two-way scale barcode. Since it can represent different numbers of characters, it is a non-fixed-length barcode.
7. Codabar barcode
The Codabar barcode was introduced in 1972 and is widely used in the medical and health and book industries. In 1977, the American Blood Transfusion Association stipulated the Codabar barcode as the standard barcode for blood bag identification.
In a Codabar barcode symbol, each character consists of 7 cells, two or three of which are wide cells and the rest are narrow cells. Kudbar chooses C(7,2) or a combination, its encoding capacity is C(7,2) + C (7,3) = 46, and its character set has only 20 characters: numbers 0-9, letters A , B , C , D , special characters $ , - , :, / , . , + . Codabar barcode has bidirectional readability. When reading Codabar barcode symbol, the determination of scanning direction is realized by terminator and start character. Codabar barcode is a barcode with strong self-checking function.
Structure of 1D Barcode Symbols
(1) Left blank area: The white area without any symbol on the left side of the barcode is mainly used to prompt the scanner to prepare to start scanning.
(2) Start character: The first character of the barcode character, used to identify the beginning of a barcode symbol, the barcode scanner starts to process the scan pulse after confirming the existence of this character.
(3) Data character: The character after the start character is used to identify the specific value of a barcode symbol, allowing bidirectional scanning.
(4) Checker: A character used to determine whether the scan is valid, usually the result of an algorithmic operation. When the barcode scanner reads the barcode for decoding, it first performs operations on the read characters. If the operation result is the same as the verification code, it is determined that the reading is valid.
(5) Terminator: A special symbol located on the right side of the barcode symbol, indicating the end of the information.
(6) Right blank area: The area outside the terminator where there is no printed symbol and the bar has the same color as the blank.
The main parameters of 1D barcode
(1) Density: The density of the barcode refers to the number of characters represented by the barcode per unit length. For a code system, the density is mainly determined by the size of the module. The smaller the module size, the greater the density, so the density value is usually expressed by the value of the module size (such as 5mil). Usually barcodes below 7.5 mil are called high-density barcodes, and barcodes above 15 mils are called low-density barcodes. The higher the barcode density, the higher the performance (such as resolution) of the barcode reading equipment required. High-density barcodes are usually used to identify small objects, such as precision electronic components, while low-density barcodes are generally used for long-distance reading, such as warehouse management.
(2) Width-to-narrow ratio: For a code system with only two width units, the ratio of the wide unit to the narrow unit is called the width-to-narrow ratio, which is generally about 2-3 (commonly used are 2:1, 3:1). When the width and narrowness are relatively large, it is easier for the reading device to distinguish between the wide unit and the narrow unit, so it is easier to read.
(3) Contrast (PCS): The optical index of the barcode symbol, the larger the PSC value, the better the optical properties of the barcode.
