In today's information society, computers are indispensable. It is the rise of automatic identification technology that provides an effective means to collect and input data quickly and accurately, and solves the "bottleneck" problem of slow computer data input and high error rate. Therefore, automatic identification technology, as a revolutionary high-tech, was quickly accepted by people.
bar codes technique
When it comes to automatic identification technology, it is inevitable to mention bar code, because it plays an important role in today's automatic identification technology. The forming process of automatic identification technology is inseparable from the invention, use and development of bar code.
Barcodes consist of a set of regularly arranged bars, spaces and corresponding numbers. This data code consisting of bars and spaces can be read by machine and easily translated into binary numbers and decimal numbers. These bars and spaces can be combined in different ways to form different graphic symbols, that is, various symbol systems, also known as code systems, which are suitable for different applications.
At present, the most commonly used coding systems are EAN, UPC, code 39, code 25 and code EAN 128. Among them, UPC barcode is mainly used in North America, and EAN barcode is an international symbol system. They are fixed-length meaningless bar codes, which are mainly used for commodity identification. Ean 128 barcode is a special barcode symbol jointly developed by EAN International (EAN) and UCC. It is a continuous, non-fixed length and meaningful high-density code, which is used to express more commodity information such as production date, batch number, quantity, specification, shelf life and receiving place. Other coding systems are mainly used to meet special needs. For example, Kudba code is used to track and manage blood banks, libraries, packages, etc. Code 25 is used for air ticket sorting in packaging, transportation and international aviation system, and code 93 is similar to code 39 with higher density and can replace code 39.
These bar codes are all one-dimensional bar codes. Due to the continuous expansion of bar code application field, higher requirements are put forward for bar code information density and information quantity in a certain area. In order to better meet this demand, a new form of bar code-two-dimensional bar code came into being. Structurally speaking, two-dimensional bar codes are divided into two categories, one is composed of matrix codes and dot codes, and its data is encoded in the form of two-dimensional space, and the other is composed of overlapping or multi-line bar code symbols, and its data is displayed in the form of a series of data lines. Overlapping symbols are code 49, code l6K and PDF4 17.
PDF is the abbreviation of portable data file, and 4 17 is related to the width code, which is used to encode characters. PDF4 17 is an overlapping code designed and introduced by SymboIInc It contains line and line end identifiers and scanning software, so data can be obtained from different parts of the tag, and it can be combined into a complete data input as long as all lines are scanned, so the data reliability of this code is very good. For PDF4 17, when the defaced or damaged part of the label is as high as 50%, all data contents can still be read.
Matrix codes, such as Maxicode, Data Matrix, Code One, Vericode, DotCode A, etc., can be made very small, and can even be used as labels for silicon wafers, so they are suitable for small objects.
Optical character recognition
Optical Character Recognition (OCR) has a history of more than 30 years. In recent years, ICR (Image Character Recognition) and ICR (Intelligent Character Recognition) have appeared. In fact, the basic principles of these three automatic identification technologies are basically the same.
Three important application fields of OCR: text input in office automation; Automatic mail processing; Other requirements related to the automatic text acquisition process. These fields include: retail price reading, order data entry, document reading, checks and documents, reading microcircuits and status characteristics of small products. With the development of handwriting recognition, the application of handwriting analysis and signature recognition has been explored.