Working principle of bar code generation and identification in supermarket automatic locker
White, black stripes of different width, the signal duration is different. However, the output of photoelectric converter and bar code and empty corresponding signal only about 10mV, can not be used directly, so the first will send electrical signals to the photoelectric converter amplifier amplifies the signal amplification after. Is still an analog signal, in order to avoid the error signals caused by the defects in the bar code and blot, in the amplifying circuit after a shaping circuit converts the analog signal into digital signal, so that the computer system can accurately evaluate.
Due to the different colors of objects, the reflective wavelength of visible light, white objects reflect various wavelengths of visible light, black objects absorb various wavelengths of visible light, so when a barcode scanner light source through an aperture and convex lens 1 after exposure to the black-and-white barcodes, light reflected by the convex after exposure to the 2 focusing lens, a photoelectric converter, and the photoelectric converter receives the reflected light signal and the corresponding strength of white and black, and converted into a corresponding electrical signal output to the amplifying and shaping circuit.
Pulse shaping circuit of the digital signal by the decoder is translated into digital information. It can recognize the character, start and end characters to identify the code and bar code symbol scanning direction; by measuring the number of pulse digital signals, 1 to 0 and the number of empty out discriminant. By measuring 0, 1 signal duration discrimination and the empty width. This has been argued to read the bar code symbol and empty number and the corresponding width and the code system, according to the corresponding encoding rules can be changed into the corresponding digital bar symbols, character information, data processing and management through the interface circuit for the computer system will complete the whole process of reading bar code identification.
