There ‘s a great way to choose a barcode scanner

In recent years, domestic major shopping malls, chain stores and other commercial enterprises have realized the huge benefits of commercial POS system to commercial enterprise management, and have built commercial POS network system. The design and installation principle of the network system is introduced in detail in various industrial journals. This paper mainly discusses how to choose one of the commercial barcode scanners as the front-end data acquisition part of the commercial POS system.

There are three common commercial barcode scanners : CCD barcode scanner, laser barcode scanner and angle laser barcode scanner.

1. CCD barcode scanner uses the principle of photoelectric coupling ( CCD ) to image the barcode printing pattern, and then decode it. Its advantages are : no shaft, motor, long service life. The price is cheap.

When choosing one CCD scanner, two important parameters are : Depth of field :

Because the CCD imaging principle is similar to the camera, if you want to increase the depth of field, the corresponding increase lens, so that the CCD volume is too large, inconvenient to operate. A good CCD should be readable without sticking to the bar code, with moderate volume and comfortable operation.

Resolution : If you want to improve the resolution of CCD, you must increase the unit element of the photosensitive element at the image. Low-cost CCD is generally five pixels, read EAN, UPC and other commercial code is enough, for other code recognition will be difficult. The mid-range CCD is more than 1024 pixels, some even up to 2048pixe1, can distinguish the narrow unit element of 0.1mm bar code.

2. The laser barcode scanner is a single-line scanner using two laser tubes as light sources. It mainly has two types : rotary mirror and vibrato mirror

Which uses a high-speed motor to drive a prism group to rotate, so that the single point laser emitted by the two tubes becomes a line. This laser line is scanned to the bar code itself. Bar code black absorbs most of the laser, and white reflects most of the laser. At the same time, the reflected light is reflected through the optical lens in the ‘ engine ’, and is focused on a photoelectric three-tube. Observations in the time domain show that the photoelectric three-tube low level on the bar code black belt, and high level on the white belt. After several amplifications, a rectangular wave is shaped, and the rectangular wave corresponds to the scanned bar code. The obtained waveform is transmitted to the decoder through the data line. ‘Decoder ‘ is actually a single chip microcomputer. It mainly depends on interrupt and single chip counter to record the waveform jump time. The collected array is decoded in the next scan or back scan. It mainly depends on the time ratio of these counters to decode the corresponding bar code. In practical application, there are many kinds of bar code, and irregular packaging wrinkles such as bubble surface, so the decoding part needs certain fault tolerance, but cannot produce error code. At present, the decoder is generally divided into 8 bit and 32 bit, 8 bit advantage is price, 32 bit is speed. The laser bar code market is cluttered with dragons, but also followed the ccd scanner dust, prices have repeatedly fallen, cottage, but there are several powerful domestic manufacturers, consumers need to carefully consider what brand, choose more suitable.

The cost of trembling mirror is lower than that of rotating mirror, but this principle of laser gun is not easy to improve the scanning speed, generally 33 times per second.

When commercial enterprises choose one of the laser scanners, it is more important to pay attention to the scanning speed and resolution, and the depth of field isn’t a key factor. Because when the depth of field increases, the resolution will be greatly reduced. A good handheld laser scanner should have high scanning speed and high resolution within a fixed depth of field.

3. The angle scanner is a barcode scanner that refracts the laser emitted by the laser diode or multiple scanning lines through the optical system. The main purpose is to reduce the labor of aligning the bar code when the cashier enters the bar code data. One of the choices should focus on the spot distribution of the scanning line :

1.There are many parallel lines in one direction

2. Multiple scan lines pass at one point

3. The interpretation probability of each point tends to be consistent within a certain space

The angle scanner which conforms to the above three points must be one of the applications of business choice.

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