It first appeared in the 1940s, and it is composed of a group of bars, spaces and their corresponding characters arranged regularly, which are used to express some information.
Extended data:
Bar code recognition principle:
In order to convert the bar code compiled according to certain rules into meaningful information, it needs two processes: scanning and decoding. The color of an object is determined by the type of reflected light. White objects reflect visible light of various wavelengths, while black objects absorb visible light of various wavelengths. Therefore, when the light from the light source of the barcode scanner is reflected, the reflected light shines on the photoelectric converter inside the barcode scanner, and the converter converts the reflected light into corresponding electrical signals according to signals with different intensities.
According to different principles, scanners can be divided into four types: light pen, red CCD, laser and image. The electric signal is output to the amplification circuit of barcode scanner, and the signal is enhanced, and then sent to the shaping circuit to convert the analog signal into a digital signal. The duration of the corresponding electrical signal varies with the width of the black and white stripes.
The main function is to prevent the width of the dead zone from being insufficient. Then, the decoder determines the number of stripes and spaces by measuring the number of 0, 1 of the pulse digital electrical signal. The width and blank space of the strip are determined by measuring the duration of 0, 1 signal. The data obtained at this time is still out of order.
In order to understand the information contained in bar code, it is necessary to convert bar code symbols into corresponding digital and character information according to corresponding coding rules (such as ean-8 code). Finally, the detailed information of the project is determined by data processing and management through the computer system.
Baidu encyclopedia-barcode