The scanning of a bar code requires a scanner, which uses its own light source to illuminate the bar code, and then uses a photoconverter to accept the reflected light and convert the light and darkness of the reflected light into a digital signal. No matter what kind of rules are taken to print the bar code, it is composed of static area, start character, data character and termination character. Some barcodes have a check character between the data character and the termination character.
▲Static area: the static area, also called the blank area, is divided into the left blank area and the right blank area, the left blank area is to let the scanning equipment ready for scanning, and the right blank area is to ensure that the scanning equipment correctly recognizes the end of the barcode mark.
In order to prevent the left and right blank area (static area) in the printing and typesetting was inadvertently occupied, can be printed in the blank area of a symbol (the left side of the print without the number of numbers & lt; No., the right side of the print without the number of numbers & gt; No.) This symbol is called the static area of the mark. The main role is to prevent the static area width is insufficient. As long as the width of the static area can be guaranteed, there is no such symbol does not affect the recognition of the barcode.
▲Starting character: the first character, with a special structure, when the scanner reads the character, it will start to read the code formally.
▲Data character: the main content of the barcode.
▲Check character: check whether the read data is correct. Different code rules may have different checksum rules.
▲Termination character: the last character, the same with a special structure, used to inform the code scanning is complete, but also play a role in just checking the calculation.
In order to facilitate bi-directional scanning, the start and stop characters have an asymmetric structure. Therefore, the scanner can automatically rearrange the barcode information when scanning. Barcode scanner has a light pen, CCD, laser three
▲ light pen: the most primitive scanning method, you need to manually move the light pen, and also with the bar code contact.
▲CCD: CCD as a photoelectric converter, LED as a light-emitting light source scanner. Within a certain range, it can realize automatic scanning. And can read a variety of materials, uneven surfaces on the bar code, the cost is also relatively inexpensive. But compared with the laser type, the scanning distance is shorter.
▲Laser: laser as a light source scanner. It can be categorized into several types such as linear, full-angle, and so on.
Linear: Mostly used in handheld scanners, far range, high accuracy.
Full-angle: mostly horizontal, high degree of automation, in a variety of directions can automatically read the bar code.