Patent GB-962271-A (GB)
Title: Improved system and means for high-speed identification of printed matter
IPC: G06V10/12
Filed: 1961-04-07
Abstract: 962,271. Automatic character reading. CONTROL DATA CORPORATION. April 7, 1961 [May 31, 1960], No. 12548/61. Heading G4R. In an automatic character reader, the characters are sensed to derive signals for each elemental part of an area covering the character indicating whether that part covers a part of the character, one or more arrays of storage devices being provided to store the elemental area signals and resistive circuits connected to predetermined patterns of storage devices, the circuit responding with an optimum signal identifying the character. In the form of Fig. 5,the character is scanned in motion by two columns of photo-cells, the light being split by a half mirror 88. The photo-cells are arranged in staggered positions so that in one set the cells lie between those of the other as shown in Fig. 1. The characters cover seven photo-cells of each set of eleven. All the photo-cell outputs are gated together at 50 to produce a start signal on the appearance of the first black parts of the character. This starts a 5-stage counter 61 to operate columns of 22 gates 31, 32, 33, 34, 35 in succession to enter five column samples of the signals into the storage columns A-E. These storage elements are connected as shift registers, the pattern being shifted down until it touches the bottom row of elements. This condition is detected by Or-gate 66 and it is used to stop the shifting process or to enable the recognition circuitry 72. Each storage element is a transistor flip-flop and has a "1" and "0" output. Combinations of outputs are connected via resistors 71 for each character to be recognised. The output of each group of resistors represents the match between the stored pattern and circuit 72 compares the signals to find the lead with the optimum value. Instead of shifting to bring the bottom edge into the bottom row of storage elements, the pattern may be moved until there is as much black above and below a given line. This compensates for ragged outlines and the presence of spurious marks. The resistors in the match circuits may be weighed at important points to assist discrimination between similar characters. E.g., for capital "O" and "Q" the tail points may be given a weighted significance. Instead of using a single storage matrix there may be a matrix for the odd photo-cells 1, 3, 5, 7 &c. and another for the even ones 2, 4, 6, 8 &c. According to the exact position of the character relative to the sets of photo-cells one or the other or both matrices will contain an accurate representation of the character. To each matrix are connected sets of resistors and for each character the higher output of the corresponding two sets is taken for comparison in the circuit 72. Further resistor sets connected to some odd and some even matrix positions recognise tilted characters. In another form the values stored may be three-state, there being at each position in the matrix three flipflops one of which is set or two flip-flops set in combination. Four, eight and ten-state values are also contemplated representing various shades of grey. For an eight-state store each position has eight flip-flops, one of which is set, or three, set in combination. The outputs are re-converted to an amplitude form by resistors and the amplitude signals are applied to resistor networks as before. Registry is also as before, the groups of flip-flops being interconnected as shift registers., The separation point between characters is found by a circuit able to detect a white column of storage cells or a zig-zag path of white storage cells crossing the matrix from top to bottom.