Automatic character recognition, in readers for blind persons - involves use of rotating disc holding character set

The process and arrangement for automatic character recognition are such as to make them particularly applicable to readers for the blind, wherein characters may be communicated mechanically or acoustically. Recognition of printed or typewritten characters is effected with the aid of a rotating disc which has characters and digits on its periphery in masks. When the printed line is scanned, character by character, a magnitude is formulated whose first term is derived by comparison with the masks, which are completely transparent, their surrounds being absolutely non-transparent. The second term on the magnitude is obtained by comparing relative density of printed areas on the page with its density at the beginning of the line, so obviating any influence of paper quality, lamp strength and photo-electric cell sensitivity.