Scanning of the barcode requires a scanner that uses its own light source to illuminate the barcode, and then uses the photoelectric converter to receive the reflected light, converting the light and dark of the reflected light into a digital signal. No matter what kind of rule is printed, the barcode consists of a quiet zone, a start character, a data character and a terminating character. Some barcodes also have a check character between the data character and the terminating character.
▲ Quiet area: The quiet area is also called the blank area, which is divided into the left blank area and the right blank area. The left blank area is for the scanning device to prepare for scanning, and the right blank area is the end mark for ensuring that the scanning device correctly recognizes the barcode.
In order to prevent the left and right blank areas (quiet areas) from being inadvertently occupied during printing and layout, a symbol can be printed in the blank area (the number is printed when there is no number on the left side, and the number is printed when there is no number on the right side); It is called the quiet zone mark. The main role is to prevent the width of the quiet zone from being insufficient. As long as the width of the quiet zone can be guaranteed, the presence or absence of this symbol does not affect the identification of the bar code.
▲ start character: the first character, with a special structure, when the scanner reads the character, it begins to officially read the code.
▲ data characters: the main content of the barcode.
▲ check character: Verify that the data read is correct. Different encoding rules may have different verification rules.
▲ Terminating character: The last character has the same special structure, which is used to inform the code to complete the scanning, and also plays the role of only the check calculation.
In order to facilitate two-way scanning, the start and stop characters have an asymmetrical structure. Therefore, the barcode information can be automatically rearranged when the scanner scans. Barcode scanners are available in four types: light pen, CCD, laser, and image.
▲ Light pen: The most original scanning method, you need to manually move the light pen and also contact the barcode.