How does barcode recognition work?

Usually when we go shopping, there are bar codes on the goods. As long as we through the way of stripe identification, we can query the information of the commodity. So do you know how bar code recognition works?

Introduction to barcode recognition

Bar code recognition refers to the use of photoelectric conversion equipment to identify the bar code technology. Our common bar code is mainly a series of wide, narrow and blank bars, and this sequence represents a certain number and letter code. And we are familiar with the barcode recognition is also scanning reading, photoelectric conversion and decoding output of three parts.

The working principle of bar code identification

The working principle of bar code recognition is mainly because different colors of the object in the reflection, the wavelength of our visible light will be different. White objects can reflect visible light of various wavelengths, while black objects can absorb visible light of various wavelengths. So the light from the bar code scanner's light source passes through the diaphragm and convex lens 1, hits the black and white bar code, and the reflected light is focused through convex lens 2 and hits the photoconverter.

So the photoelectric converter receives the reflected light signal with the corresponding strength of the white bar and the black bar, and converts it into the corresponding electrical signal and outputs it to the amplifying shaping circuit, which converts the analog signal into the digital electrical signal, and then translates it into the digital character information by the decoding interface circuit.

Because the width of the bar code varies, the duration of the corresponding electrical signal varies. However, with the output of the photoelectric converter corresponding to the bar and space of the bar code the signal is only about 10mV. It can not be used directly, so it is necessary to put the electrical signal of photoelectric output in the amplifier to amplify, so that the information of the product can be seen.