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Understanding of the structure of the bar code and the principles of reading

- May 16, 2018 -

Understanding of the structure of the bar code and the principles of reading

Guided Reading: Bar code is a graphic identifier of a set of numbers or alphabetic symbols. It is composed of bars and spaces with different widths, different reflectances, and certain coding rules (code system).

The bar code is a graphic identifier that is composed of bars and spaces with different widths, different reflectivity, and according to a certain coding rule (code system) to express a set of digital or letter symbol information. That is, the bar code is a set of parallel line graphics with different thickness and arrangement according to certain rules. The common bar code is composed of black bars (abbreviated bars) and white bars (abbreviated as empty bars) with large differences in reflectivity, which are usually printed on goods. Or on the package, it can replace all kinds of text information, and can read data at any time through the photoelectric reading device.

The EAN bar code system consists of barcode symbols themselves, bar code reading, interfaces, and computers to complete the input and output of commodity information. There are two kinds of barcode reading symbols, bar code symbols for the rectangular line graphics, optical scanner information readout system, mainly to read and identify these bar code symbols. The numeric symbols are numbers and letters outside the line, including 0-9 digits, A-Z letters, which can be directly recognized by the naked eye, generally from 8 to 16 digits, and the code system has different digits.

The arrangement, width, and number of lines of the bar code are stipulated by each manufacturer and determine the meaning of the code.

Generally, there are marks at the two ends of the reading end-reading, and some still have numbers printed under the lines, which can be directly identified or read by an optical reader, and thus can also count, count, and manage commodities.

The reading performance of the barcode system, that is to say whether the barcode system can be used normally depends on the reading ability of the system and the printing quality of the barcode. Bar code, as a kind of coded information, is a specific language that people communicate with the computer.

Black and white thickness and white line symbol in bar code, thick black line as 1 in the computer, fine black lines represent 0, through logic conversion, can be expressed as 0-9 Arabic numerals and arrays, therefore, there must be a reading device Use it together to read.

The reading system mainly includes a scanner and a decoder. The scanner is a part that directly contacts the bar code reading signal. It consists of a light emitter, a photo detector, and an optical lens. It can read the information abbreviated by the bar code at an extremely fast speed.

During scanning, when the light beam emitted from the light emitter shines on the bar code, the photo detector responds according to the light intensity of the light beam reflected from the bar code when the scanning light spot sweeps onto the white paper surface or between the two black lines. In the blank space, the reflected light is strong and the detector outputs a large current.

When scanning to black lines, the reflected light is weak, the detector outputs a small current, and according to the black line width or narrow to make a different response time, with the light and dark changes in the bar code into a different size of the current signal, after the amplification of the transmission Go to the decoder. The decoder translates the signal into data, performs local inspection and display, and connects with the keyboard and sends it to the computer for data processing.

How bar code printing quality! It is related to the ability to read questions properly. Therefore, the ink is uniform, the layout is not dirty, the lines are clear without breaking, and it is the basic quality requirement for bar code printing.