To convert a barcode compiled according to certain rules into meaningful information, it is necessary to go through two processes of scanning and decoding. The color of an object is determined by the type of light it reflects. White objects can reflect visible light of various wavelengths, while black objects absorb visible light of various bar code wavelengths. Therefore, when the light emitted by the bar code scanner source is reflected on the bar code, The reflected light is irradiated onto the photoelectric converter inside the barcode scanner, and the photoelectric converter converts into a corresponding electrical signal according to the reflected light signal of different strengths and weaknesses.
According to the difference of the principle, the scanner can be divided into four types: light pen, red light CCD, laser, and image. After the electrical signal is output to the amplification circuit of the barcode scanner, the signal is sent to the shaping circuit to convert the analog signal into a digital signal. The widths of the white bars and the black bars are different, and the duration of the corresponding electrical signals is also different.
The main role is to prevent the width of the quiet zone from being insufficient. The decoder then discriminates the number of bars and spaces by measuring the number of pulsed digital electrical signals 0,1. The width of the strip and the space are discriminated by measuring the duration of the 0, 1 signal. The data obtained at this time is still cluttered. To know the information contained in the barcode, the bar symbol is replaced with the corresponding number and character information according to the corresponding coding rule (for example: EAN-8 code). Finally, data processing and management is performed by the computer system, and the detailed information of the item is identified.