GB1130574A - Improvements in or relating to visual pattern identification systems - Google Patents

Abstract

1,130,574. Pattern recognition. PLESSEYUK Ltd. 1 Feb., 1966 [4 Nov., 1964], No. 44970/64. Heading G4R. [Also in Division H1] A visual pattern is impressed upon an array of photo-sensitive elements coupled to integrated logic circuits incorporating gate circuits to produce an electric output representative of the pattern. Light reflected from a printed or written character is focused on to the array, individual elements of which are connected in groups to the logic circuits to recognize particular features (such as straight lines, or particular curves) or whole characters. The logic circuit outputs may punch cards or tape for computer input. Constructional details.-The array of photosensitive elements is part of a sandwich consisting of layers as follows, in order, transparent electrode, photo-conductive layer of cadmium sulphide, forest of conductive rods in insulator, silicon substrate, earthed conductor, insulator, logic circuit input connections, insulator, positive voltage supply conductors arranged mutually parallel, insulator, negative voltage supply conductors mutually parallel but orthogonal to the positive conductors, and insulator. The logic circuits are formed along one edge of the sandwich in an integrated manner as a sandwich of a layer of input terminals, a layer of partially conducting material, a layer of conductive rods in insulator, and a silicon substrate. A modification uses photo-transistors in place of the photo-conductive layer. As a further modification, the logic circuits could be interspersed with the photo-sensitive elements.