Bar codes (one-dimensional codes) and two-dimensional codes are mainly used as identification of items. Barcodes are mainly used in product identification, anti-counterfeiting, medical supervision, supermarket checkouts, etc. QR codes can contain more information, such as URLs, text, pictures, etc., even a poem, an article, etc., in the Internet age The application is gradually becoming popular.
One-dimensional code:
QR code:
the difference:
1. The amount of information carried by the two-dimensional code is much greater than that of the one-dimensional code
The information part of a one-dimensional code can only be letters and numbers, and its size is relatively large, which means that its space utilization rate is low. This determines the limitation of its small amount of information. Its data capacity is relatively small and generally can only hold about 30 characters. The two-dimensional code is different, its information carrying capacity is very large, the maximum data content can reach 1850 characters. Information content can include letters, numbers, Chinese characters, characters, katakana, etc. The information content is very rich. Therefore, QR codes have gradually been accepted by the market, and the addition of Chinese characters has opened up the big market in China.
2. The two ways of expressing information are different
According to its characteristics and structure, we can see that a one-dimensional code can only express product information in one direction in the horizontal direction, but does not express any information in the vertical direction. Its certain height is usually to facilitate the alignment and reading of the barcode device. take. The two-dimensional code can express information in both horizontal and vertical directions, which means that it stores information in a two-dimensional space.
3. The external structure of the two is different
According to Figure 1 and Figure 2, we can see that their structures are completely different. One-dimensional code is a bar code that expresses information in the horizontal direction with a bar space. The shape is closer to a rectangle. A two-dimensional code can be said to be a square, with three "back" positioning points inside it, which can help the barcode device to focus and facilitate the reading of data. It is also the difference in their structure that the one-dimensional code has no strong error correction function. If the bar code is damaged, it cannot be read. For the QR code, even if it is damaged, it can be read normally. Its damage error correction rate can reach 7%~30%.
4. The code system of the two is different
In the current code system, one-dimensional code and two-dimensional code each have their own code system and constituent members. Commonly used one-dimensional code codes include: EAN code, 39 code, cross 25 code, UPC code, 128 code, 93 code, ISBN code, and Codabar (Codabar code), etc.; the commonly used two-dimensional code code system includes ：PDF417 two-dimensional barcode, Datamatrix two-dimensional barcode,, QR Code, Code 49, Code 16K, Code one, etc.
5. Different manifestations in barcode printing software
One-dimensional code and two-dimensional code can be said to be two completely different barcodes, and their production and expression in barcode printing software are also different. Generally speaking, the one-dimensional code and the two-dimensional code are represented separately in the software. That is to say, when making a barcode, you must first distinguish whether it is a one-dimensional code or a two-dimensional code, and then choose the code system to be made. For example, in the leading barcode printing software , these two barcodes have 
and 
to distinguish them. The former represents a one-dimensional code, and the latter represents a two-dimensional code.
6. Performance of advantages and disadvantages
The advantage of a one-dimensional code is to express information in one direction, and its certain height is usually to facilitate the alignment of the scanner. The one-dimensional code can increase the speed of information entry and reduce the error rate. The disadvantage is that the data capacity is relatively small, a computer database is required, and the one-dimensional code cannot be read after it is destroyed, and the error tolerance rate is low.
The advantages of the QR code are large information capacity, wide coding range, low cost, easy production, and a large amount of data can be stored without the database itself. The fault-tolerant mechanism of the two-dimensional code ensures that the image part is damaged and can be correctly identified and fault-tolerant. The rate can be as high as 30%. The disadvantage is that it is easy to be implanted by criminals to steal user information or various fee-absorbing software.
Composition structure:
Version information: the specifications of the QR code. Above >= Version 7, two 3 x 6 areas need to be reserved to store some version information.
Data information and error correction information: the actually saved two-dimensional code information (Data Code data code) and error correction information (Error Correction Code) (used to correct errors caused by damage to the two-dimensional code).