1, UPC (Uniform Product Code)
It can only represent numbers. There are five versions: A, B, C, D and E. Version A- 12-bit version E-7-bit version. The last bit is the parity bit. The size is 1.5 "high 1", and the background should be clear. Mainly used in the United States and Canada, used in industry, medicine, warehousing and other departments.
When UPC is decoded into twelve bits, it is defined as follows: first bit = digital ID (established by UCC (Unified Coding Committee)).
Bits 2-6 = manufacturer's identification number (including the first bit), 7- 1 1 = unique manufacturer's product code, and bit 12 = used for error detection.
2. Code 3
Can represent letters, numbers and other symbols ***43 characters: A-Z, 0-9,-. $/+%.The length of the pacing bar code can be changed. Usually "*" is used as the starting and ending symbols. The code density is 3-9.4 characters/inch, and the blank area is 10 times of the narrow strip, which is used for checking codes.
3. Code 128
Represents high-density data, with variable string length and symbols containing check codes. There are three different versions: A, B and C can use 128 characters in the three string sets of A, B or C for industry, warehouse, retail and wholesale.
Insert paper
2 out of 5 (I2 out of 5)
It can only represent numbers 0 -9, variable length and continuous bar code. 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. Barcodes have high reading rate, can be used for reliable scanning of fixed scanners, and have the highest density among all one-dimensional barcodes.
4、Codabar
(Kudbama)
It can represent the numbers 0-9, the characters $,+,-and the four characters A, B, B and C, which can only be used as start/stop symbols. It has variable length and no parity bit, and is used in material management, libraries, blood stations and current airport parcel delivery.
The blank area is wider than the narrow bar 10, which is a discontinuous bar code, and each character is represented as 4 bars and 3 spaces. Codabar, also known as NW 7, is called in Japan.
5. QR code
The QR code is square, and black and white are common. On the three corners, small square patterns similar to the word "Hui" are printed. These three modes are helpful to the positioning of decoding software, and users do not need to align them. No matter scanning at any angle, the data can still be read correctly.
Japanese two-dimensional code standard JIS X 05 10 was released in June 2000, and its corresponding ISO international standard ISO/IEC 18004 was approved in June 2000.
Densovave's website shows that QR code is an open standard, and its specifications are open. Densovave holds a patent right, but it will not operate.
In addition to the standard two-dimensional code, there is also a format called "micro two-dimensional code", which is a reduced version of the two-dimensional code standard and is mainly designed for applications that cannot handle large-scale scanning. Micro QR codes also have various standards, and can store up to 35 characters.
6、PDF4 17
(QR code)
Barcodes composed of multiple lines can store a large amount of data without connecting to a database. They are used in hospitals, driver's licenses, 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 a product developed by Symbol Technology Company in 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.
Extended data:
Dimension code difference:
One-dimensional barcode
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 the convenience of 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 shortcomings:
Small data capacity: about 30 characters.
It can only contain letters and numbers.
Bar code size is relatively large (low space utilization)
The bar code cannot be read after it is damaged.
Two-dimensional bar code
Barcodes that store information in two-dimensional space in horizontal and vertical directions are called two-dimensional barcodes.
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
Based on the principle of one-dimensional bar code coding, multiple one-dimensional codes are vertically stacked. Typical coding systems are: code 16K, code 49. PDF4 17, etc.
2. Matrix QR code
According to the different distribution of black and white pixels in the matrix, they are coded in rectangular space. Typical coding systems include: Aztec, Maxi code, two-dimensional code, data matrix and so on.
3. Postal code
Bar codes with different lengths are mainly used for mail coding, such as Postnet and BPO 4-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. , in which:
* The data matrix is mainly used to identify small parts in the electronics industry, such as the code printed on the back of the Intel Pentium processor.
* Maxi Code was developed by United Parcel Service (UPS) to sort and track parcels.
* Aztec is introduced by Welch Allyn Company of the United States, and can accommodate up to 3832 numbers or 3067 alphabetic characters or 19 14 bytes of data.
Color bar code
Color barcodes are mainly combined with mobile phones or personal computers with video lenses, which are used to read color barcodes on magazines, newspapers, televisions or computer screens and transmit them to data centers. The data center will provide website information or consumption discount according to the received color bar code.
The advantage of color bar code over two-dimensional bar code is that it can provide higher data capacity with lower resolution.
On the one hand, color bar codes don't need a high-resolution lens to interpret, which makes the communication change from unidirectional to bidirectional. Secondly, the low resolution also makes companies that use barcodes add changes to barcodes to enhance readers' interest in participating.
The new color bar code will use 4 or 8 colors to store more information in a smaller space and replace the traditional rectangle with a small triangle.
According to the picture released by CNET news, it looks like a color version of a two-dimensional QR barcode. In the future, color bar codes are planned to be used in commercial media such as movies and video games to provide higher security and even link movie videos or other additional functions.
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