GB1166759A - Character Readers - Google Patents

Abstract

1,166,759. Character recognition. ALMEX A.B. 28 July, 1967 [29 July, 1966], No. 34938/67. Heading G4R. A character reader comprises two rows of photodetectors over which an image of the character is swept, a preamplifier having a gain varied inversely to the character contrast, a register in which the character is reconstituted and shifted to a standard position to feed recognition means, and checking means. In Fig. 2, a line of characters on moving strip R is scanned by rotating mirrors S and projected by optics O on to two orthogonal lines X, Y of photo-cells across which the image sweeps. The photo-cell outputs pass via preamplifiers and threshold amplifiers to a character register into which the signals derived from the Y photo-cells are entered and shifted to a standard position under control of the X photo-cells. The outputs of the preamplifiers control their gains to compensate for different printing densities and cause reduction of the threshold levels of the threshold amplifiers in the case of weak signal. The rate of movement of strip R is sufficiently slow comparatively for several recognition attempts to be made on each character with successively lower threshold levels in case recognition is not possible first try. This also compensates for characters being vertically displaced in the printed line. When a character has been fully entered into the character register it is recognized to produce ideally a signal on one of a plurality of lines. If more than one line is marked, the largest signal is taken. The character identity is inserted into a position register at a position corresponding to that of the character in the printed line. When the position register is presumably full (it may have a " blank " indication in some positions), its contents are transferred into a further register via a coder (after a check on the code produced) and provided a comparison of blank/not-blank signals from the further register and the position register indicates no discrepancy, the contents of the further register are passed to another register and, on receipt of a request from a computer, to the latter.