Fri Jan 06 10:51:48 CST 2023
The first thing to understand is what a bar code is,
Barcode character: represents the number of lines and blanks of a character.
Bar: The part of the bar code with low reflectance to light, usually black.
Blank: The part of the bar code with high reflectance to light, usually white.
Blank area: The area with the same color as the space reserved at both ends of the bar code to ensure normal reading of the bar code
Start character: A special bar code character at the start position of the bar code.
Terminator: A special bar code character at the end of the bar code, indicating the end of the bar code.
Check bit: A barcode character used to verify the accuracy of the barcode. It is generated according to certain check rules according to the character information represented by the barcode. Generally, it is located before the terminator.
Unit: A width range of the same color in the bar code character. A unit consists of one or more modules. Module: The most basic unit of the bar code.
His broad categories are as follows:
1. Code 39: Code 39 is a bar code introduced by Intermec in 1975
2, commodity code: (EAN, UPC code) business is the earliest application of bar code technology. In the business automation system, commodity bar code is the key.
3. Code 93: It has the same character set as 39, but its density is higher than 39
4, Code 128 code: it can represent a total of 128 characters from ASCII 0 to ASCII 127, so called 128 code
5. Matrix 25: It can only represent the numbers 0 to 9
6, cross-insert 25 code: it is a kind of bar code and empty are expressed information bar code, cross-insert 25 code has two kinds of unit width, each bar code character consists of five units, two wide units, three narrow units
7, PDF417 two-dimensional bar code: tickets have, PDF417 bar code is the biggest advantage of its huge data capacity and strong error correction ability