In the world of computers, the scanner is a device that optically scans images, printed or written text, a three-dimensional object, etc. representing it in a digital format.
The now ubiquitous device can be found in offices as a desktop (or flatbed) scanner, where the document is placed on a glass window for scanning; in engineering and creative labs as a 3D scanner, used for industrial design, reverse engineering, test and measurement, gaming and other applications; in printing shops as a very-high-quality drum scanners, that are superior in resolution, colour gradation, and value structure.
Modern scanner may be considered the successor of early fax and telephotography input devices from 19th century.
The first "fax” device, according to computer.com, was developed in early 1840s by the Scottish inventor Alexander Bain (1811–1877), who is primarily known as the inventor of the first electric clock in 1841. On 27 May, 1843, Bain received a British patent (№9745) for improvements in producing and regulating electric currents and improvements in timepieces and in electric printing and signal telegraphs, and later made some improvements in his next patent (№10838), granted on 25 September 1845.
The punched paper tape was introduced by Alexander Bain on 12 December, 1846, when he patented so called chemical telegraph. He had seen that the Morse and other telegraphs then in use were comparatively slow, due to the mechanical inertia of their moving parts, and realised that the signal current could be used to make a readable mark on a moving paper tape soaked in a mixture of ammonium nitrate and potassium ferrocyanide, which gave a blue mark when a current was passed through it.
Bain’s chemical telegraph was tried in France between Paris and Lille, and attained a speed of 282 words in 52 seconds, a great advance on Morse’s telegraph which could only give about 40 words per minute. Later it was used in England and USA, but never really entered general usage.
The first practical operating electromechanical commercially exploited fax machine, the Pantelegraph, was invented in 1861 by the Italian physicist Giovanni Caselli (1815-1891).
The first scanner developed for use with a computer, was a drum scanner (see the image below). It was built in 1957 at the US National Bureau of Standards by a team led by Russell A. Kirsch, working on America’s first internally programmable (stored-program) computer, the Standards Eastern Automatic Computer (SEAC), in order to enable Kirsch’s group to experiment with algorithms that launched the fields of image processing and image pattern recognition.
According to techwalla.com, computer scanners came into their own in the 1990’s, and although the advent of digital capture devices has diminished the need for their services, they remain popular---even after a surprisingly long history. Scanners continue to evolve, currently offering high resolution output at a fraction of the cost and size of their progenitors.