GB1162607A - Character Checking - Google Patents

Abstract

1,162,607. Character recognition. INTERNATIONAL BUSINESS MACHINES CORP. 12 July, 1967 [14 July, 1966], No. 31978/67. Heading G4R. A group of printed encoded characters on a document includes at least one check character, and each character is represented by a fixed number of code positions to each of which is allocated a predetermined one of a plurality of code elements and the check character has its code elements so selected that for each code position the number of times a selector code element occurs in the characters other than the check character, bears a predetermined relationship to the code element in the corresponding code position in the check character. Legible characters printed on a document are each constructed from seven vertical strokes with parts missing to provide the character shape, each of the six gaps between adjacent strokes having one of two breadths, the combination of breadths identifying the character to character recognition apparatus. A group of the characters is augmented by a further character the nth gap of which (for each n) provides a parity check for the nth gaps of the characters in the group. As each character is read it is converted to six binary pulses which are inserted into a shift register and then passed out in parallel to a set of six bi-stables each of which performs a parity check for a respective gap position. A special symbol following the augmented group of characters on the document causes an error signal to be produced if any of the six parity checks shows an error, and resets the bi-stables.