Working Principle of Scanner

28.07.2020 0 iCODIS Official

In recent years, scanners have become an important part of families and offices. Scanner technology is ubiquitous and used in a variety of ways. A flat-plate scanner, also known as a desktop scanner, is the most functional and commonly used scanner. Let's learn how the scanner works together.

  1. Working principle of scanner - introduction

As the third generation of computer input equipment after keyboard and mouse, the scanner is a high-precision photoelectric integrated high-tech product, using photoelectric technology and digital processing technology to input various forms of image information into the computer. It can scan, analyze and convert images such as photos, printed documents, or handwritten documents, or small objects such as ornaments into digital images by capturing images and converting them into the form that can be displayed, edited, stored, and output on computers. People usually use scanners to input computer images which are the most informative form, and at work, maybe you need a pdf camera scanner.

  1. Working principle of scanner - structure

The components of a typical flatbed scanner include CCD array, reflector, scanning head, glass plate, lamp, lens, upper cover, color filter, stepping motor, balance rod, transmission belt, power supply, interface port, and a control circuit.

The CCD array is the core component of the scanner. CCD is the most commonly used technology in the field of scanner image capture. CCD is composed of a large number of tiny photosensitive diodes( light spots), which can convert photons (light) into electrons (charge). In short, each light spot is sensitive to light - the brighter the light incident on a single light spot is, the more charge accumulated in this light spot is. The scanned document image passes through a series of mirrors, color filters, and lenses to reach the CCD array. The specific arrangement of these components depends on the scanner model, but the basic principle is roughly the same.

  1. Working principle of the scanner

The working principle of the scanner is not complicated, which can be basically reflected in its working process. Just like high speed camera scanner, it scans the original document optically, then transmits the optical image to a photoelectric converter to be converted into an analog electrical signal, and then converts the analog electrical signal into a digital electrical signal, and finally sends it to the computer through the computer interface.

The steps of scanning images by the scanner are as follows: firstly, the front face of the manuscript to be scanned is laid down on the glass plate of the scanner, and the manuscript can be a text or a drawing photo; after the scanner driver is started, the movable light source installed inside the scanner starts scanning the original. In order to uniformly illuminate the manuscript, the scanner light source is oblong and sweeps the whole manuscript along the Y direction. The light irradiated on the manuscript passes through a very narrow gap after being reflected to form a light band along the X direction, passes through a group of reflectors, and focused by an optical lens and enters a spectroscope, and three RGB color light bands obtained through a prism and a red, green and blue color filter respectively shine on respective CCD, the CCD converts the RGB light band into an analog electronic signal, and the signal is converted into a digital electronic signal by an A/D converter.

Now, the optical signal reflecting the original image is converted into a binary digital electronic signal acceptable to the computer and finally sent to the computer through serial or parallel interfaces. The scanner obtains one line of image information of the original document in the X direction every time it scans one line. As it moves along the Y direction, the original document is gradually formed inside the computer.

working priciple of a scanner