Barcode scanning knowledge

2022-11-16 | 22 view
The scanner illuminates the bar code with its own light source and uses a photoelectric converter to receive the reflected light and convert it into a digital signal.

 

The scanner illuminates the bar code with its own light source and uses a photoelectric converter to receive the reflected light and convert it into a digital signal. Regardless of the rules used to print a barcode, it is composed of a static area, a starting character, a data character, and a ending character. Some barcodes have a check character between the data character and the termination character.

Barcode scanning requires a barcode scanner, which uses its own light source to illuminate the barcode and uses a photoelectric converter to receive the reflected light and convert the light and shade of the reflected light into a digital signal.

Regardless of the rules used to print a barcode, it is composed of a static area, a starting character, a data character, and a ending character. Some barcodes have a check character between the data character and the termination character.

Static area: Static area is also called blank area, which is divided into left blank area and right blank area. The left blank area is to make the scanning device ready for scanning, while the right blank area is to ensure that the scanning device can correctly identify the end mark of the barcode.

In order to prevent the left and right white space (static area) from being unintentionally occupied during printing and typesetting, a symbol can be printed in the blank space (left without the number < If there is no number on the right, print it. This symbol is called the quiet zone marker. The main function is to prevent insufficient width of the static zone. As long as the width of the static area can be guaranteed, the symbol does not affect the recognition of the bar code.

Start character: The first character with a special structure. When the barcode scanner reads the character, it begins to read the code.

Data character: The main content of the barcode.

Check character: verifies that the data read is correct. Different encoding rules may have different check rules.

Termination character: The last character, again with a special structure, is used to inform the code that the scan is complete, but also to perform a verification calculation.

To facilitate bidirectional scanning, the start and end characters have an asymmetric structure. Therefore, the barcode scanner can automatically rearrange barcode information when scanning. Bar code scanner has light pen, CCD, laser three.

Light pen: The most primitive scanning method involves moving the light pen manually and touching the bar code.

CCD: CCD as a photoelectric converter, LED as a light source of the barcode scanner. In a certain range, automatic scanning can be realized. And can read a variety of materials, uneven surface of the bar code, the cost is relatively low. However, compared with laser, the scanning distance is shorter.

Laser: A scanner that uses a laser as its source of illumination. It can also be divided into linear, full Angle and so on.

1, linear: used for handheld bar code scanner, far range, high accuracy.

2, full Angle: mostly horizontal, high degree of automation, in all directions can automatically read the bar code.