Since objects of different colors reflect 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 source After passing through the aperture and convex lens 1, when it shines on the black and white bar code, the reflected light is focused by the convex lens 2 and then shines on the photoelectric converter, so the photoelectric converter receives reflections of different strengths corresponding to the white bars and black bars. The optical signal is converted into the corresponding electrical signal and output to the amplification and shaping circuit. The width of the white bars and black bars is different, and the duration of the corresponding electrical signals is also different. However, the electrical signal output by the photoelectric converter corresponding to the bars and spaces of the barcode is generally only about 10mV and cannot be used directly. Therefore, the electrical signal output by the photoelectric converter must first be sent to an amplifier for amplification. The amplified electrical signal is still an analog electrical signal. In order to avoid false signals caused by defects and stains in the barcode, a shaping circuit needs to be added after the amplification circuit to convert the analog signal into a digital electrical signal so that the computer system can accurately interpret it. ．

The pulse 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 barcode symbol by identifying the start and end characters; it identifies the number of bars and spaces by measuring the number of 0 and 1 pulse digital electrical signals. Determine the width of bars and spaces by measuring the duration of the 0 and 1 signals. In this way, the number of bars and spaces of the barcode symbol being read, the corresponding width and the code system used are obtained. According to the encoding rules corresponding to the code system, the bar symbols can be replaced with corresponding numbers and character information. The interface circuit is sent to the computer system for data processing and management, thus completing the entire process of one-dimensional barcode reading[