Bar code structure

- May 19, 2020-

1. Basic terms of barcode


Bar code is an information code that USES special graphics to represent number, letter information and some symbols. Figure A is the bar code of miaofu-style cake of hangzhou dingyuan food co., LTD. Bar code consists of a set of bars of the same width, reflectance, and space that are combined according to certain coding rules to represent a symbol of complete data. Usually, a human-recognizable character is noted below the barcode symbol.


Bar code element: the bar and space used to represent a bar code, referred to as the element.


Bar code character: a set of bar code elements used to represent a number, letter, 


Bar: in a bar code symbol, the less reflective element.


Null: the element with a higher reflectance in the barcode symbol.


Bit empty: in a bar code symbol, the empty space between two adjacent bar code characters that represents any information.


Bar height: the longer dimension of a bar in two dimensions.


Bar width: in a bar code symbol, the length that excludes the two sides of the static area.


Unit element length: in the barcode symbol, the nominal width of the narrow element is the unit element width, denoted by X.


Two element wide bar codes: in a bar code character, if the element has only two widths, the wide element and the narrow element, the code is called a multiple element wide bar code.


Multiple element wide bar codes: in a bar code character, if an element has three or more widths, the code is called a two-element wide bar code.


Bar code logical value: for two types of element width and length code, the logical value of the wide element is 1, the logical value of the narrow element is 0, for a variety of elements of the wide bar code, if the unit element width is a bar, the logical value is 1 bar code, if the unit element width is empty, the logical value is 0.


Continuous code, discrete bar code: in the bar code symbol, if there is a bit space between two adjacent bar code characters, this code system is called discrete bar code, otherwise called continuous bar code.


Barcode general partition: static zone start character data character check character termination character static zone.


Bar code of fixed length and variable length: in the bar code symbol, if the symbol contains and the number of bar characters is fixed, this code system is called the length fixed bar code: otherwise, it is called the variable bar code.


Self-validating barcode: if a misprint does not cause a character to be translated into another character in the code system, the code system is called a self-validating barcode. (n, k) code: a continuous bar code with multiple element widths, also known as (n, k) code. N refers to the number of single element widths in the barcode character, and K refers to the number of bars or empty Spaces in a character.


Barcode symbol density: refers to the number of barcode characters per unit length.


Barcode character set: the barcode character set refers to the range of data characters given in the barcode system. The range of data characters given in various bar codes. There are two types of character sets in various bar codes. One is the digital character set, which contains the digits 0~9 and some special characters. The other is the alphanumeric and digital character set, which includes the digits 0 to 9, the letters A to z, and some special characters.


Smudge: a point in an empty or quiet area that is similar to the reflectance of a strip.


2. Structure of barcode symbol

A complete bar code symbol is composed of two side static, start character, data character bar code, check character (optional), and stop character.