Input device is one of the main devices for information exchange between users and computer systems. Keyboard, mouse, camera, scanner, light pen, handwriting board, joystick, voice input device, etc. All belong to input devices.
Scanner is a device that uses photoelectric technology and digital processing technology to convert graphic or image information into digital signals through scanning.
Scanners are usually used as external instruments of computers, which capture images and convert them into digital input devices that computers can display, edit, store and output.
Scanners can scan three-dimensional objects, such as photos, text pages, drawings, artistic pictures, photographic negatives, films, and even textiles, signs, printed board samples, etc. , and extract and convert original lines, graphics, characters, photos and plane objects into devices that can be edited and added to files.
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Computer input devices can be divided into the following categories according to their functions:
1. Character input device: keyboard;
2. Optical reading equipment: optical mark reader and optical character reader;
3. Graphical input devices: mouse, joystick and light pen;
4. Image input equipment: cameras, scanners, fax machines;
5. Analog input equipment: language analog-to-digital conversion recognition system.
Scanners can be divided into three types: pen scanners, portable scanners and drum scanners.
1. pen scanner appeared around 2000, and the scanning width is only about 4 Chinese characters. When it is used, it is pasted on paper and scanned line by line, which is mainly used for character recognition.
2. Portable scanners are small and fast, and there are many new concept scanners on the market. Because of their excellent scanning effect, the scanning speed is only 1 second, the price is moderate, and the scanner is very small, which is deeply loved by enterprises and offices.
3. Drum scanners generally use photomultiplier tubes (PMT), so it has a large density range and can distinguish more subtle level changes of images; The plane scanner uses CCD (Charge Coupled Device), so its scanning density range is small.
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