Bar code is a set of parallel black and white stripes with different widths, which are widely used in our daily life. Barcodes can be seen on the packaging of ordinary daily necessities, and on the back cover of officially published books, periodicals and magazines.
Bar code technology was born with the development and application of computer and information technology. It is a new technology integrating coding, printing, identification, data acquisition and processing, and can collect and transmit information economically, quickly and accurately. Simply put, the purpose of bar code is to convey information.
Wrigley gum is the first product with a bar code. Bar code technology first appeared in the 1920s and was born in Westinghouse Laboratory. An eccentric inventor named John Comand "whimsically" wanted to sort postal documents automatically.
His idea is to make a bar code mark on the envelope, and the information in the bar code is the address of the recipient, just like today's postal code. For this reason, Comander invented the earliest bar code mark, and the design scheme is very simple (note: this method is called modular comparison method), that is, one represents the number "1", two represents the number "2", and so on. Then, he invented a bar code reading device composed of basic components: scanner (which can emit light and receive reflected light); A method for measuring the band and space of reflected signal, namely edge positioning coil; And a method of using the measurement result, namely a decoder. Shortly thereafter, douglas young, Comand's collaborator, made some improvements to Comand's code.
"Comande" code contains very little information, and can only encode ten different regions, so it is difficult to compile more than ten different codes. "Yang" code uses fewer bar codes, but it can code 100 different areas in the same space.
At present, the commonly used barcodes in the world are ENA barcode, UPC barcode, 25 barcode, cross barcode, Kudba barcode, Sanjiu barcode and 128 barcode. Code39 is used in the automobile industry, and it is the symbol specification of the automobile industry stipulated by AIAG, which has a certain effect on the technical guidance of the world automobile industry. The most commonly used commodity is EAN commodity bar code, also known as general commodity bar code, which is formulated by ean international and widely used all over the world. It is the most widely used commodity bar code in the world. At present, China is promoting the use of this commodity bar code. EAN commodity bar codes are divided into EAN- 13 (standard version) and EAN-8 (abbreviated version).
Sometimes, we will see that the bar code cannot be read, and the cashier will input the numbers on the bar code into the computer one by one, so the bar code becomes a "language" that the machine can recognize. This is where the bar code designer is considerate. When the bar code reading equipment has problems, it can be recognized by human eyes, so characters for human recognition are added to various bar codes. Therefore, bar codes are not only composed of vertical lines and spaces with different widths, but also include corresponding characters. According to the appearance characteristics of bar codes, they are called bar codes, cosmic rays and zebra crossings abroad.
Using bar code scanning is the general trend of future market circulation. In order to make goods circulate freely and widely in the world, there must be a unified code. Many industries or groups in the world have stipulated their own codes for the use of bar codes. Enterprises, whether designing, manufacturing, applying for registration or using commodity bar codes, must follow the relevant provisions on the management of commodity bar codes.
Bar code in the mathematical world