Classification and working principle of barcode scanners
Scanning guns can be divided into three categories: one-dimensional laser scanning guns, one-dimensional CCD scanning guns and two-dimensional CMOS scanning guns.
Principle of one-dimensional laser scanning gun
The one-dimensional laser scanner scans the code through the principle of laser reflection. The main components of the one-dimensional laser scanning gun are laser source, light collector, swing device (with mirror), photosensitive receiver tube, photoelectric conversion circuit, electrical signal amplification, shaping, quantization circuit, and decoding circuit.
The laser tube emits red laser light, the laser beam is expanded through the beam expander lens, and then hits the surface of the swingable mirror to reflect on the barcode to form a laser spot. When the mirror swings, according to the principle of optical reflection, the position of the laser point on the barcode changes and the mirror continuously oscillates, then a red laser line will be seen on the barcode, which is caused by the phenomenon of visual persistence. When the laser line hits the bar code, because the surface of the bar code is rough, the laser spot on the bar code is reflected, and the reflection intensity of the bar and the space of the bar code is different. Reflected to the light collector, the light is collected by the light collector, and the stray natural light is filtered out by the filter to enter the photodiode to generate a photoelectric induction signal, which is then amplified, shaped and decoded to become decoded information, decoded chip, decoded The chip is decoded successfully and then transmitted to the device. Through the one-dimensional laser principle we analyzed above, we can know that the most important principle of the one-dimensional laser scanning gun is laser reflection, then we can only know the reflection principle through paper reflection. If it is a paperless screen, the reflected signal cannot be obtained correctly. So one-dimensional laser scanning can only scan one-dimensional barcodes printed on paper.
Principle of one-dimensional red light CCD scanning gun
The scanning principle of one-dimensional CCD red light scanning gun is the principle of linear CCD imaging. It is mainly composed of an optical lens, a fill light circuit (including a cylindrical mirror), a CCD linear sensor, a signal amplifying circuit, and a decoding circuit.
The CCD linear sensor is the main component of the one-dimensional CCD red light scanning gun.
A CCD sensor is a photoelectric conversion device that can store signal charges generated by light. When a pulse with a specific timing is applied to it, the stored signal charge can be directionally transmitted in the CCD to achieve self-scanning. It is mainly composed of photosensitive unit, input structure and output structure. It has functions such as photoelectric conversion, information storage and delay, and has high integration and low power consumption. It has been widely used in three major fields of camera, signal processing and storage.
There are two types of CCD sensors currently on the market. One is a 1500-dot image, and the other is a 2500-dot image.
Principle of 2D CMOS Scanner
The two-dimensional CMOS scanner mainly consists of a lens, a CMOS sensor, a fill light circuit (some products do not have it), an auxiliary aiming tube circuit (some products do not), and a decoding circuit.
The 2D CMOS scanner is based on the principle of CMOS imaging. After the CMOS sensor images the barcode, it converts the image signal into an electrical signal and transmits it to the decoding circuit, and the decoding circuit parses the barcode information through the image algorithm.
Contact Person: Mr. Allen