How barcode scanners work

- Aug 17, 2018 -

Rich life With the involvement of color printers, the families of ordinary people have become more colorful. In recent years, the rapid development of computer technology, some families have more needs - scanning guns. It also provides a new way of rapport for family entertainment. Before you choose to use the scanner, first recognize the scanner. As a high-tech product closely integrated with optical, mechanical, electronic, software applications and other technologies, the scanner is the third generation of major computer input devices after keyboard and mouse. Since the birth of the scanner in the 1980s, it has been rapidly developed and widely used. From the most direct pictures, photos, film to various drawings and documents, documents can be input into the computer with a scanner to realize these images. Processing, management, use, storage or output of information.

1. Scanner interface:

There are three common types of interfaces for scanners:

(1) SCSI (Small Computer Standard Interface): The maximum number of connected devices on this interface is 8. Usually, the maximum transmission speed is 40M/S, which is faster and generally connects to high-speed devices. The installation of SCSI devices is more complicated. Generally, a SCSI card is added to the PC, which is easy to generate hardware conflicts, but it is powerful.

(2) EPP (Enhanced Parallel Interface): An enhanced bidirectional parallel transmission interface with a maximum transmission speed of 1.5 Mbps. The advantage is that there is no need to use other cards in the PC, unlimited number of connections (as long as you have enough ports), the device is easy to install and use. The downside is that the speed is slower than SCSI. This interface replaces the SCSI interface in the low-end and low-end performance requirements due to its ease of installation and use.

(3) USB (Universal Serial Bus Interface): Up to 127 peripherals can be connected. The current USB1.1 standard has a maximum transmission speed of 12 Mbps and has a secondary channel for transmitting low-speed data. In the future, if there is a USB 2.0 standard scanner speed may be extended to 480M / s. Hot pluggable, plug and play. The scanner of this interface has become popular with the establishment and promotion of the USB standard under the push of Intel.

2. Scanner internal structure and working principle:

Common flatbed scanners generally consist of a light source, an optical lens, a scanning module, an analog to digital conversion circuit, and a plastic housing. It uses the photoelectric element to convert the detected optical signal into an electrical signal, and then converts the electrical signal into a digital signal through an analog to digital converter for transmission to a computer for processing. When scanning an image, the light source illuminates the image and the reflected light passes through the lens to converge onto the scanning module. The scanning module converts the optical signal into an analog digital signal (ie, the voltage, which is the intensity of the received light). Related), also pointed out the degree of darkness of that image. At this time, the analog-to-digital conversion circuit converts the analog voltage into a digital signal and transmits it to the computer. The color is quantized by the 8, 10, and 12 bits of the RGB three colors, and the signal is processed into the image output of the above number of bits. If there is a higher number of quantization bits, it means that the image can have a richer level and depth, but the color range has exceeded the recognition ability of the human eye, so for us, the higher-order scanner for the range of resolution The effect of scanning is that the color is smooth and you can see more details.

3. Scanner resolution:

The resolution of the scanner is determined in three ways: the optical part, the hardware part, and the software part. That is to say, the resolution of the scanner is equal to the resolution of its optical components plus its own resolution obtained by processing analysis by hardware and software.

The optical resolution is the actual number of spots that the optical component of the scanner can capture per square inch of area. It refers to the physical resolution of the scanner CCD (or other optoelectronic device) and the true resolution of the scanner. The value is the value obtained by dividing the pixel point that the photoelectric element can capture by the maximum scanable size of the scanner. For example, a scanner with a resolution of 1200 DPI often has a resolution of only 400 to 600 DPI. The resolution of the extended part is jointly generated by hardware and software. This process is generated by computer analysis of the image and mathematical filling of the blank part (this process is also called interpolation processing).

The optical scan and output are one-to-one, what is scanned, and what is output. After processing by computer hardware and software, the output image will become more realistic and the resolution will be higher. Most of the scanners currently on the market have software and hardware expansion capabilities for resolution. Some scanners write 9600×9600 DPI, which is only the maximum resolution obtained by software interpolation, not the true optical resolution of the scanner. So for the scanner, the resolution has optical resolution (or optical resolution) and maximum resolution. Of course, we care about the optical resolution. This is hard work.

We say that a scanner has a resolution of up to 4800 DPI (this 4800 DPI is the sum of optical resolution and software difference processing), which means that when scanning an image with a scanner, it can collect 4800× on a 1 square inch scanning surface. 4800 pixels (Pixel). The 1 inch square scan area, scanned at a resolution of 4800 DPI, produces an image size of 4800 Pixel x 4800 Pixel. When scanning an image, the higher the scan resolution is set, the finer the effect of the generated image, and the larger the generated image file, but the more the interpolation components.