Bar code technology originated in the twenties of the last century, was born in Westinghouse laboratory. Inventor named John Kermode eccentric is "fantastic" to think of the postal documents for automatic sorting, then for every conceivable application of electronic technology have made people feel very strange.
His idea was to do on the envelope bar code label, bar code information is the recipient's address, as today's postal code. For this purpose the invention Kermode first bar code identification, the design is very simple (Note: This method is called comparison module), i.e. a "bar" represents the number "1", two "strip" indicates the number "2", inferior race analogy. Then, he invented a bar code reader apparatus by a base element consisting of: a bar code scanner (capable of emitting light and receiving reflected light); a reflected signal measured by the method of bars and spaces, i.e., edge of the positioning coils; and using the measurement results of method, i.e. the decoder. Behind the bar code printers appear, which greatly facilitates the production of bar code bar code labels.
Note: The following is the People's Republic of China National Standard GB T 12905-2000 in / barcode barcode term.
1, the marker, and the space bar code corresponding to the bar code characters by using a series of rules consisting, to indicate certain information.
2, bar code system bar code symbol by the bar code system design, production and scanning reading system composed.
3, the reflectance reflectance; reflectivity and reflected light intensity ratio of incident light intensity.
4, projected onto the diffuse reflection deffuse reflection phenomenon of a rough surface reflecting light in all directions.
5, the mirror specular reflection phenomenon projected light reflected in all directions a smooth surface.
6, bar bar; dark bar; black bar in the bar code portion of lower reflectivity.
7, the empty space; light bar higher reflectivity barcode portion.
8, the start character start character; start cipher; start code is located several pieces of starting position with empty barcode.
9, terminator stop character; stop cipher; start code is located several pieces of the bar code with the blank end position.
10, blank area clear area; quiet zone; quiet area ; clear zone
bar code symbol start, termination symbol ends same reflectance and the outside space defined area.
11, the bar code symbol comprising a bar code symbol barcode free area.
12, a set of bar code symbol character seet character set can represent letters, numbers, and symbols.
13, the intermediate separator central seperating character located at an intermediate position of bar code data segment used to separate several pieces and empty.
14, separated from one kind of separator character coded character set separator acting special characters.
15, the bar code character bar code character indicates a character or symbol and empty several pieces.
16, the character set of the bar code barcode bar code character set character set can be represented by a certain bar code.
17, bar code data character of bar code bar code data character represented by the character-specific information.
18, the bar code check character bar code check character checksum character represents the barcode.
19, the bar code filler bar code filler character does not represent a specific character of bar code information.
20, the cell element constituting the barcode strip or blank characters.
Height dimension 21, a high bar height bars are perpendicular to the cell width direction.
22, the width dimension of the strip width bar width bar code of the character strip.
23, the width dimension of the empty space wide space width bar code characters.
24, wider than the strip barcode bar width ratio of the widest narrow bar width than the best.
25, the empty space width ratio wider than the widest empty barcode narrowest width than air.
26, X dimension X Dimension
Nominal dimension X of the bar code symbol in a narrow cell.
27, Z dimension Z Dimension
actual bar code symbol narrow dimension Z units.
28, the width to narrow ratio than the width
N of the average width of the strip width and the strip width of the average width of the empty space, and (do not count the bar code character spacing) divided by twice the Z dimension. It is the width parameter adjustment technique encoding method.
Formula: N = (mean strip width wide strip empty average width + space width) / 2Z
29, the length of the bar code from the bar code length to the length of the leading edge of the bar code symbol start trailing edge terminator.
30, the length of the bar code symbol bar code symbol length; symbol length comprises the length of the blank to the bar code.
31, wherein aspect ratio than the length of the barcode stripe height ratio.
32, the number of characters of the bar code bar code density bar code density per unit length of the bar code represents.
Note: usually expressed in CPI, that is, the number of characters per inch bar code can be represented.
33, the bar code character spacing adjacent inter-character gap does not represent the same specific information and reflectivity empty region between the bar code characters.
34, encoding module module module group with the basic unit consisting of the barcode method character.
35, the protective frame surrounding the bearer bar and the bar code with the same reflectance strip or edge frame.
36, continuous type barcode continuos bar code Bar code characters without spacing.
37, discontinuous discrete bar code bar code with a bar code of the bar code character spacing.
38, both ends of the bar code the bar code symbol can be bi-directional as bi-directional bar code scanning start point of the bar code.
39, additional add-on bar code bar that shows the additional information.
40, parity and odd-even check method for verifying according to the number of binary digits 1 or 0 is odd or even.
41, the self-check bar code self-checking bar code with the bar code characters themselves barcode checking function.
42, a fixed length bar code fixed length of the fixed number of bar code barcode bar code character.
43, the non-fixed length barcodes unfixed length of the barcode data characters in bar code of the bar code is not fixed.
44, the width adjusting method of encoding a width encode bar code symbol by the wide bars and spaces, both units consisting of the narrow bar code encoding method.
45, bar code encoding method of character set coding scheme module Method module combination encode bar code symbols by a plurality of modules of predetermined composition.
46, binary codes binary-edge-code both units of two character width Bar code width units.
47, polyhydric four-edge-code code element width bar code has more than three or three units width character bar code.
48, arranged in odd odd permutation; odd parity coding method with block set, a character contained in the barcode bars and the number of modules is arranged in an odd number.
49, even the arrangement even permutation; even parity coding method with block set, the arrangement and number of modules contained in the bar of a bar code even number of characters.
50, the bar code bar code logic value logical expression represented by the characters represented by bar code binary "0" and "1."
51, the bar code encoding the encoded volume capacity of the maximum number of characters in the character set can be represented.
52, the original film the bar code barcode bar code film master film master.
53, one-dimensional bar linear bar code; one-dimentional bar code represented by the barcode symbol information in only one dimension.
54, the two-dimensional bar code represented by two-dimentional bar code information of the bar code symbol in a two-dimensional direction.
55, the bar code made of special material, special barcode special bar code.
56, the bar code character values of the character values of the intermediate value converted to one-dimensional bar by the bar code character set logical formula.
57, two-dimensional bar code word codeword value character. An intermediate of formula is converted by the bar code as the character set logic value.
58, error correction error correction character characters two-dimensional bar code, error detection and error correction characters.
59, error correction code word error correction codeword two-dimensional bar code, the value of the error correction characters.