1. What is bar code? What are the benefits of using barcode?

Bar code is a group of bar and empty symbols arranged according to certain coding rules, which is used to represent certain characters, numbers and symbols.

Advantages: 1. Reliable and accurate. The speed of data input is fast. It's cheap. 4. Flexible and practical. 5 degrees of freedom. The equipment is simple. 7 easy to make.

2. Barcode printing process

3. What is the bar code system? Bar code system: the coding rules of bar code are unique, permanent and meaningless.

4. Classification of bar code and code system?

4.1 one dimensional bar code: it expresses information in one direction (generally in the horizontal direction), while it does not express any information in the vertical direction. Its height is usually for the convenience of reader alignment. Disadvantages: 1. The data capacity is small: about 30 characters; 2. It can only contain letters and numbers; 3. The size of the bar code is relatively large (the space utilization is low); 4. The bar code cannot be read after it is damaged Code39 (standard 39), Codabar (kudebar), code25 (standard 25), itf25 (cross 25), matrix25 (matrix 25), UPC-A, upc-e, EAN-13, ean-8, code128

4.2.1 ean 13 / 8: ean bar code symbols can be divided into standard version and shortened version. The standard version is composed of 13 digits and the shortened version is composed of 8 digits.

EAN13 has 13 digits in total: the first three digits on the left are the country code, China 690 ~ 692; the next four digits are the manufacturer code; the next five digits are the product code (each manufacturer can allocate 100000 kinds of goods produced by itself); the last one is the check code, which is calculated from the previous 12 or 7 digits. In addition, as special commodities, books and periodicals also use EAN13 to represent ISBN and ISSN. The prefix 977 is used for ISSN, and the prefix 978 is used for ISBN. In China, the ISBN with the beginning of 7 is assigned. Therefore, all the barcodes on the books published by China's publishing houses are 9787. Its components are as follows: · left blank area, 11 modules wide. It consists of three modules. The data symbol on the left represents 6-digit information, which is composed of 42 modules. The middle separator is composed of 5 modules. The data character on the right side represents a group of bar code characters with 5-digit information, which is composed of 35 modules. Check character, composed of 7 modules. The terminator consists of three modules. The right blank area has a minimum width of 7 modules. For human identification characters, 13 digits corresponding to bar code. The minimum distance between the top of the character and the bottom of the barcode character is 0.5 module wide. The prefix of EAN-13 bar code for human identification is printed on the left side of the starting character of bar code symbol.

4.2.2 UPC code: like ean barcode, UPC barcode is a kind of American commercial barcode. There are two kinds of UPC barcode: Standard Version and shortened version. The standard version is composed of 12 digits and the shortened version is composed of 8 digits.

4.2.3 code39 code (also known as code 3 of 9) has only two cell widths: wide cell and narrow cell. The characteristics of code39 code are as follows: 1. Each character is composed of 9 elements with 5 bars and 4 spaces, and there are spaces between characters; 2. It can represent numbers, letters and other symbols with 44 characters (0-9, A-Z, -, space, *, $, /, +,%)