The hand-held scanner is a product that was introduced in 1987 and looks like a bar code scanner used by supermarket cashiers. Most of the holding scanners use CIS technology, and the optical resolution is 200dpi. There are many types of black and white, grayscale and color. The color type is generally 18-bit color. There are also some high-end products that use CCD as a light-sensing device, which can achieve true color and good scanning effect.
Small drum scanner
This is the middle product of hand-held scanners and flat-panel scanners. (There has been a new emergence in recent years, because it is built-in power supply and small size is called notebook scanner.) Most of the products use CIS technology, and the optical resolution is 300dpi, available in color and grayscale, color models are generally 24-bit color. There are also a few small drum type scanners that use CCD technology, and the scanning effect is significantly better than that of CIS technology. However, due to structural limitations, the volume is generally significantly larger than that of CIS technology.
The small drum type is designed to fix the lens of the scanner, and the object to be scanned is scanned through the lens. When it is operated like a printer, the object to be scanned must pass through the machine and be sent out. Therefore, the object to be scanned cannot be too thick. The biggest advantage of this kind of scanner is that it is small in size, but because of its various limitations, for example, it can only scan thin paper, the range can not exceed the size of the scanner.
Also known as flat-bed scanners, desktop scanners, most of the scanners currently on the market belong to flat-panel scanners, which is now the mainstream. These scanners have an optical resolution between 300 dpi and 8000 dpi, color bits from 24 to 48, and a scan format of A4 or A3. The advantage of the flat type is that like the copying machine, as long as the top cover of the scanner is opened, whether it is a book, a newspaper, a magazine or a photo negative film can be put on and scanned, which is quite convenient, and the scanning effect is also in all common types of scanning guns. the best.
Others include large-format scanners for large-format scanning, wireless scan code guns, pen-type scanners, bar code scanners, and film scanners. (Note that it is not a flat-panel scanner plus a sweep, the effect is much better, and the price is of course expensive. ), physical scanners (not flat scanners with physical scanning capabilities, somewhat similar to digital cameras), as well as drum-type scanners mainly used in the field of printing and typesetting.