One dimension form code just is in a direction (it is horizontal way commonly) expressive information, and do not convey any message in perpendicular direction, the height that decides firstly is to facilitate of reader normally alignment.
One dimension the rate that the application of form code can raise information to type, reduce accident rate, but one dimension the part that form code also puts in a few inadequacy:
* data capacity is lesser: 30 character are controlled
* can include letter and number only
* form code dimension is opposite bigger (dimensional utilization rate is inferior)
* after form code suffers damage, cannot read
A form code of the information of memory of 2 dimension space in level and perpendicular direction, call 2 dimension form code (2-dimensional Bar Code) .

With one dimension form code is same, 2 dimension the encode method that form code also has a lot of differring, or say the code is made. the encode principle that makes with respect to these codes, can divide normally for the following 3 sort
1.2 dimension pile up linear pile type is in one dimension on the foundation of principle of form code encode, pile up many one dimension in fore-and-aft pile generation. Be like,typical code makes: Code 16K, Code 49, PDF417.
2.2 dimension pile up matrix type is in rectangular space is passed black, white differ mediumly in matrix like element distributing have code. Be like,typical code makes: Aztec, Maxi Code, QR Code, Data Matrix.
3.Postal code passes different length have code, basically use at mail encode, be like: Postnet, BPO 4-State.

The 2 dimension in a lot of sort in form code, commonly used code makes have: Data Matrix, maxi Code, aztec, QR Code, vericode, PDF417, ultracode, code 49, code 16K, among them:
* Data Matrix basically is used at the label of electronic industry small part, those who be like Intel gallop the reverse side of processor printed this kind of code.
* Maxi Code is by the United States associated wrap up serves (UPS) the company develops, the sorting that is used at wrap up and dog.
* Aztec is by American Wei Lin (Welch Allyn) the company rolls out, can contain 3832 numbers or 3067 data of alphabetical character or 1914 byte at most.

Below, we are with PDF417 code exemple, introduce 2 dimension the character of form code and characteristic.

One) PDF417 brief introduction

PDF417 code is by Chinese leaving the United States Wang Yin is respected (sound) the doctor invents. PDF is to take English Portable Data File the abbreviate of the initial of 3 words, meaning for " portable data file " . Because form a body,the each symbol character of the code is by 4 form for nothing with 4, what if will form a body,pile up is the narrowest or call a module for nothing, afore-mentioned 4 a total module number with 4 sky is fixed for 17, call code or 417 PDF417 the code so.

2) the characteristic of PDF417

1.It is OK that the code divides data capacity big PDF417 outside showing character of letter, number, ASCII, still can convey binary number. To make encode more compact, increase information density, PDF417 is coding from time to tome 3 kinds of formats:
Previous12 Next

Previous:Bar code and foreground of union of wireless local area network are valued!
Next：Clothing company how printer of bar code of choose and buy