GB1371493A - Apparatus and methods for character recognition - Google Patents

Abstract

1371493 Character recognition systems MASSON SCOT THRISSELL ENG Ltd 4 Oct 1971 [10 Sept 1970 9 Oct 1970] 43447/70 and 48237/70 Heading G4R Characters specially shaped to facilitate automatic character recognition are formed of straight line portions, e.g. of selected ones of 9 lines as at 20, Fig. 1. Each of the 9 possible lines in a character is sampled at a point between its ends, e.g. at 21-29, Fig. 3, providing a 9-bit signal which identifies the character. As applied to the recognition of postal code written on printed grids 11-16 on an envelope, the envelope is passed before a cathode-ray tube. When a photodetector senses the leading edge 60 of the envelope a flash lamp is fired so that a stationary image of the postal code, together with control marks 30, 41, 42, is impressed on the tube. Scan control circuiting causes the C.R.T. beam to perform a raster scan 40, Fig. 3, to detect the leading control marks 41, 42. When the start of the control marks 30, 31 associated with the first character grid 11 is detected the scan changes to pass through each of the 9 lines of the grid. The scan path may be as in Fig. 3, or as in Fig. 4 or 5 (not shown). The C.R.T. output passes to a gate which samples the signals corresponding to points 21-29. The samples pass to a recognition unit which generates a binary coded decimal respresentation of the character recognized. After a character is scanned the scan reverts to raster form to search for the control marks of the next character. The recognition unit is wired to detect not only correctly formed characters but also characters which are incorrectly formed or off-centre, as described with reference to Fig. 8 (not shown). To reduce the sensitivity of the system to unwanted marks on the envelope, or to gaps in the character lines, the C.R.T. beam is wobbled to provide a broader scan, Fig. 9 (not shown).