Patent GB-1345686-A (GB)
Title: System for automatically reading symbols
IPC: G06V10/12
Filed: 1972-02-18
Abstract: 1345686 Character recognition systems DE STAAT DER NEDERLANDEN TENDEZE VERTEGENWOORIDG DOOR DE DIRECTEUR - GENERAAL DER POSTERIJEN TELEGRAFIE EN TELEFONIE 18 Feb 1972 [19 Feb 1971] 7590/72 Heading G4R [Also in Division G2] A scanning system in a character recognition system employs a camera tube having a photosensitive surface with a width to height ratio R, an array of characters being imaged on to the tube by an assembly of bundles of glass fibres.  The exit face of the assembly has a width: height ratio R and preferably is the same size as the photo-sensitive surface. Each bundle of fibres carries light from a particular area of a document bearing the characters, each such area being rectangular and being marked on the document by a frame having a width : height ratio R. The frames in which the characters are written or typed are red and may be arranged as in Fig. 9a, for example, the glass fibre bundles being so arranged that they are presented to the camera in the format shown in Fig. 9b. The camera spot size is less than that of one fibre in section, and scanning takes place in a raster of vertical scan lines. The camera is rendered insensitive to the red frames by an optical filter. During each scan line, in each portion corresponding to scan over the height of one character frame, a signal is generated indicating the number of sequences of black character elements (or intersections) in that portion: if numerals onlv are to be detected this number should never exceed 3. Signals are also generated, indicating the height within the frame of the beginning and end of each such sequence of black elements. The signals are passed to a data processor, which recognizes the characters and may operate a punch. The processor allots the signals relating to each character frame to one of four groups w-z dependent upon the significant largest number of black sequences (or intersections) defined by the signals. A number of sequences 2 or 3 is significant only if there is this number of sequences in at least four successive scan lines. The groups and the numerals in those groups are shown in Fig. 46. The manner in which the signals are then used depends upon the selected group. Group x. The signals representing the heights of the start and end of the centremost scan line of the group of lines showing one black sequences are noted. Also, by comparing the heights of the starts of the sequences in the scan lines to the left of the centre-most line the highest start is determined and noted. Similarly, the lowest end in the lines to the left and the highest start and lowest end in the lines to the right are also noted. The processor now performs operations to determine, for example, the height of the character, differences in height between the starts of the centre scan and the highest start to the left, &c., to determine which of the numerals has been scanned, Fig. 26 (not shown). Group y. The signals representing the heights of the starts and ends of black sequences are used to determine, for example, whether the sequences merge or diverge on the right or left, &c., to distinguish the numerals in this group, Fig. 27 (not shown). Group z. Operations similar to those in respect of group y are performed, Fig. 29 (not shown).