In developed countries, supermarkets have become the center for people to buy goods, and most small and medium-sized markets and stores also use the method of optional selling. In China, optional shopping malls are also emerging. On the shelves of supermarkets or shopping malls equipped with electronic cash registers, there are basically no products without bar code marks
. Even in other stores, experienced housewives take a serious look at whether there is a bar code on the package when choosing goods. So, what does the bar code mean, how does it read, and what role does it play in commodity circulation? This has to start from the bar code's life experience.
Bar code symbol is a group of parallel lines with different thickness and spacing arranged according to a specific format. Hundreds of millions of different kinds of special information can be generated by the different combination and arrangement of lines, which can record the country of production, name of manufacturer, product category, characteristics, production date and other information of each commodity, so as to realize automatic sales. In the beginning, Western European countries mainly used it in the management of the storage and sales of food and groceries. By 1985, it had developed into the circulation of general commodities. At present, nearly 200000 kinds of goods in the world are automatically scanned and sold due to the use of bar code.
In order to adapt to the international trend and promote the export of commodities, "China Commodity coding center" formally joined this international organization on behalf of China on May 14, 1991, and successively established sub centers in Guangdong, Shenzhen, Hubei, Jiangsu, Shanghai, Zhejiang, Liaoning and Sichuan, Together with the Ministry of Commerce, China Commodity coding center is building an automatic sales system (POS) for supermarkets. By the end of 1992, hundreds of Chinese export enterprises had obtained the qualification of using international general bar code, and more than 3000 kinds of export products had been bar coded.
The "eyes" of bar code reading
are bar code scanners. At present, the scanners can be divided into laser scanners and non laser scanners. Laser reader can scan automatically and has a large field of view depth, and is a non-contact scanner, which can accurately read the bar code of all kinds of goods, bringing good news to housewives who often wait in line in front of the cash register.
Since 1974, when the first laser bar code scanner
came out in the world, the desktop bar code scanning technology with He Ne laser has become more and more mature, and has been used in the automatic checkout system of commercial outlets. In 1982, a hand-held He Ne laser bar code scanner
with moving beam was developed, which can scan bar code automatically by deflection mirror. Although this kind of He Ne laser scanner needs a large driving power supply, it is widely used because of its convenient use and complete functions. In 1987, 75000 units were sold in the U.S. retail industry alone, and 125000 units were sold in 1988. In order to reduce the volume, we began to study the use of diode laser as light source in 1986. In 1988, visible diode laser came out, providing low-cost, low-power solid-state devices. It is not only suitable for the scanning of hot printing paper and blue-green symbols, but also makes it possible to miniaturize and lighten the hand-held bar code reader.
At present, visible diode laser scanners
are gradually replacing He Ne laser scanners and occupying most of the bar code market in the world. According to incomplete statistics, 300000 visible diode laser scanners have been put into use. The whole scanning system is installed in a light and small laser scanning head and connected with the main computer system through the cable plug. Its service life has reached 250000 hours. At present, it has formed an important laser bar code industry together with coding, storage and retrieval technology.