The barcode is made by the US N. T. Woodland first proposed in 1949. In recent years, with the increasing popularity of computer applications, the application of barcodes has been greatly developed. Barcodes can indicate the country of manufacture, manufacturer, product name, date of manufacture, book classification number, start and end of mail, category, date, etc., and thus are available in many fields such as commodity circulation, book management, post and telecommunications management, and banking systems. A wide range of applications.

Chinese name Bar code recognition principle Presenter N. T. Woodland Time 1949

 

History

Bar code technology first appeared in the 1940s. At that time, two engineers in the United States studied bar code to represent information and obtained the world's first bar code patent in 1949. This earliest bar code consists of several black and white concentric circles and is aptly called a bull's eye bar code. This bar code is in principle consistent with our widely used one-dimensional bar codes, which use dark bars and light spaces to represent the "1" and "0" of the binary number. However, at that time, the level of the printing industry in the United States and the development of the commodity economy were not yet capable of using bar code technology.

Twenty years later, in 1966, IBM and NCR launched the world's first bar code technology application system based on the feasibility of using scanners and computers in store sales settlements. This system records the price of the item on the magnetic strip of the package. When the item passes through the scanner, the scanner reads the information on the magnetic strip.

In 1970, the American Grocery Industry Association initiated the formation of the US Uniform Code Council (UCC). The establishment of UCC marks the full acceptance of bar code technology by the US business community. In 1972, the UCC organization used the UPC barcode as a uniform commodity code for commodity identification, and determined that the generic commodity code UPC barcode was widely used as a barcode standard in the United States and Canada. This measure laid the foundation for the unification and wide application of commodity barcodes in the future.

In 1973, manufacturers and distributors in 12 countries including France, the United Kingdom, the Federal Republic of Germany, and Denmark in Europe initiated and prepared the European article coding system. And in 1977 the European Association of Article Coding was established. Referred to as the EAN Association. The EAN Association has introduced a bar code that is compatible with UPC bar codes: EAN bar code. This new thing appeared in Europe and immediately attracted the interest of manufacturers and distributors in many countries around the world. Many non-European and American countries in the world have also joined the EAN Association. In 1981, the European Association of Article Coding was renamed the International Article Coding Association, or IAN. Because of the customary name, it is still called the EAN organization until today.

China established the China Article Coding Association in 1988 and officially joined the EAN organization in April 1991. At present, the prefix code used in China's goods is 690,691,692,693 allocated by EAN International to China.

 

Bar code

Because bar code technology and computer technology have many advantages, it is widely used not only in the field of commodity circulation, but also in other fields such as post and telecommunications, banking, library, logistics management, and even the most popular e-commerce, production, supply and sales. Integrated supply chain management is widely used. Therefore, there are still a lot of bar codes for management, such as 128 bar codes, 39 codes, cross two-five codes, CODABAR codes, etc. These bar codes are one-dimensional bar codes for managing the system.

With the expansion of the application of bar code technology, people's demand for bar code technology is also increasing. People not only require bar code technology to solve the problem of computer data input speed and data input accuracy, but also hope that bar code technology can solve it. Multi-information printing on smaller areas and other issues. In the late 1980s, a new bar code that could display more information on a smaller area was created.

It is a two-dimensional barcode. Since the two-dimensional barcode can represent information in the horizontal and vertical directions of the plane, compared with the one-dimensional barcode, the amount of information and the information density carried by the two-dimensional barcode are improved several times, and the two-dimensional barcode can represent images, characters, Even the sound. The emergence of two-dimensional bar codes has enabled bar code technology to transform from simply identifying items to describing items. Its function has undergone qualitative changes, and the application field of bar code technology has expanded.

Originated in the 1940s, research in the 1960s, popular in the 1980s, popular in the 1980s, developed in the 1990s bar code technology, as a printable computer language, played its irreplaceable role. It can be predicted that with the advent of economic globalization and the era of information networking, the application prospects of bar code technology will be beautiful. [1]

 

Overview

A bar code is a symbol that combines lines and spaces according to certain coding rules to represent certain letters, numbers, and the like. In the identification process, a bar code reader (a bar code scanner is also called a bar code scanner or a bar code reader) is scanned to obtain a set of reflected light signals, which are photoelectrically converted into a group and lines and blanks. The corresponding electronic signal is decoded and restored to the corresponding text number, and then transmitted to the computer.

Barcode technology is an automatic identification technology widely used in business, postal, library management, warehousing, industrial production process control, transportation, etc., which is produced and developed in computer application and practice. It has fast input speed and high accuracy. The advantages of low cost and high reliability play an important role in today's automatic identification technology. Nowadays, barcode identification technology is quite mature. The error rate of reading is about one millionth, and the first reading rate is more than 98%. It is a high reliability, fast input, high accuracy, low cost and wide application. Automatic data collection technology. There are more than 225 one-dimensional barcodes in the world. Each one-dimensional barcode has its own set of coding specifications. Each letter (may be text or number or number) is composed of several lines (Bar) and several A space composition, and an arrangement of letters. Generally, the more popular one-dimensional barcodes are 39 yards, EAN code, UPC code, 128 code, and ISBN, ISSN, etc., which are specially used for book management.

 

Recognition principle

Since objects of different colors have different wavelengths of visible light, white objects can reflect visible light of various wavelengths, and black objects absorb visible light of various wavelengths. Therefore, when the light emitted by the barcode scanner light passes through the aperture and the convex lens 1, When irradiated onto the black and white bar code, the reflected light is focused by the convex lens 2, and then irradiated onto the photoelectric converter, so that the photoelectric converter receives the reflected light signals different in intensity from the white bars and the black bars, and converts them into corresponding The electrical signal is output to the amplification shaping circuit, and the shaping circuit converts the analog signal into a digital electrical signal, which is then translated into digital character information via the decoding interface circuit.

 

The width of the white strip and the black strip are different, and the duration of the corresponding electrical signal is also different. However, the electrical signal output by the photoelectric converter and the bar and space corresponding to the bar code is generally only about 10 mV, which cannot be directly used. Therefore, the electric signal output from the photoelectric converter is first sent to the amplifier for amplification. The amplified electrical signal is still an analog electrical signal. In order to avoid the error signal caused by defects and stains in the barcode, a shaping circuit is needed after the amplifying circuit to convert the analog signal into a digital electrical signal so that the computer system can accurately interpret the signal. .

 

The pulsed digital signal of the shaping circuit is translated into digital and character information by the decoder. It identifies the code system and scanning direction of the bar code symbol by identifying the start and end characters; the number of bars and spaces is determined by measuring the number of pulsed digital electrical signals 0, 1. Determine the width of the strip and the space by measuring the duration of the 0 and 1 signals. In this way, the number of bars and spaces of the bar code symbol to be read and the corresponding width and the code system used are obtained. According to the coding rule corresponding to the code system, the bar symbol can be replaced with the corresponding number and character information. The interface circuit is sent to the computer system for data processing and management, and the entire process of barcode reading is completed.

 

System composition

In order to read the information represented by the barcode, a barcode recognition system is needed, which is composed of a barcode scanner, an amplification shaping circuit, a decoding interface circuit, and a computer system.

 

Technical advantage

Barcode is by far the most economical and practical automatic identification technology. Bar code technology has the following advantages:

A. Fast input speed: Barcode input is 5 times faster than keyboard input and enables "instant data entry".

B. High reliability: keyboard input data error rate is one-three percent, using optical character recognition technology error rate is one in ten thousand, and bar code technology error rate is less than one millionth.

C. The amount of information collected is large: the traditional one-dimensional barcode can be used to collect information of dozens of characters at a time, and the two-dimensional barcode can carry thousands of characters of information, and has certain automatic error correction capability.

D. Flexible and practical: Barcode identification can be used as a means of identification alone, or it can be combined with related identification equipment to realize automatic identification, and can be connected with other control equipment for automatic management.

In addition, barcode labels are easy to manufacture, there are no special requirements for equipment and materials, identification equipment is easy to operate, no special training is required, and equipment is relatively inexpensive.

 

Coding mode

A bar code is a set of bar and space symbols arranged according to a certain coding rule to represent information consisting of certain characters, numbers and symbols.

The bar code system is an automatic identification system consisting of bar code symbol design, production and scanning reading.

Common code system

There are many types of barcodes, and there are probably more than twenty code systems, including:

Code39 code (standard 39 code), Codabar code (Cudba code), Code25 code (standard 25 code), ITF25 code (cross 25 code), Matrix25 code (matrix 25 code), UPC-A code, UPC-E code , EAN-13 code (EAN-13 international product barcode), EAN-8 code (EAN-8 international commodity barcode), China Post code (a variant of matrix 25 code), Code-B code, MSI code, Code11 code, Code93 code, ISBN code, ISSN code, Code128 code (Code128 code, including EAN128 code), Code39EMS (39 codes for EMS) and other one-dimensional barcodes and two-dimensional barcodes such as PDF417.

 

Bar code type

The internationally widely used bar code types are EAN, UPC codes (commodity bar codes, which are used to uniquely identify a product in the world. The most common one in supermarkets is this bar code), Code39 code (which can represent numbers and letters, in The management field is the most widely used, ITF25 code (more applications in logistics management), Codebar code (used in medical and book fields), Code93 code, Code128 code, etc.

Among them, EAN code is widely used in the world, and has become the basis of electronic data interchange (EDI); UPC code is mainly used in the United States and Canada; in various bar code application systems, Code39 code can use digital It is widely used in the internal management of various industries in the form of a combination of letters; Codebar codes are also widely used in the business of blood banks, libraries and photo studios.

In addition to the one-dimensional barcodes listed above, 2D barcodes have also been rapidly developed and found in many fields.

Common bar code

EAN code:

The EAN code is a bar code for goods developed by the International Association of Article Codes and is used worldwide. The EAN code symbol has two types: the standard version (EAN-13) and the shortened version (EAN-8). The general commodity barcode of our country is equivalent to it. The barcode printed on the packaging of the goods we buy on a daily basis is generally the EAN code.

UPC code:

The UPC code is a commodity bar code developed by the United States Uniform Code Committee. It is mainly used in the United States and Canada. We can see it on goods imported from the United States.

39 code:

39 code is a bar code that can represent numbers, letters and other information. It is mainly used for the automatic management of industry, books and tickets, and is widely used.

Codebar code:

Kudba code can also represent digital and alphabetic information, mainly used for automatic identification in the fields of health care, library information, materials and so on.