Patent GB-991450-A (GB)
Title: Character recognition system
IPC: G06V30/224
Filed: 1963-11-18
Abstract: 991,450. Automatic character reading. INTERNATIONAL BUSINESS MACHINES CORPORATION. Nov. 18, 1963 [Nov. 23, 1962], No. 45359/63. Heading G3R. In a character-reading apparatus the characters are scanned to produce signals representing the character and other signals representing the position of register of the character, the register signals being adapted to gate out selected parts of the character signals to recognition circuity. The characters are specially shaped as shown in Fig. 8 so as to have bars in a combination of seven positions. All characters have a horizontal bar in the bottom position VL and this is used as a start mark for vertical registration. All characters also have a vertical bar in either or both the upper or lower right-hand positions HUR, HLR which is or are used as a start mark for horizontal registration. The characters printed on a tape are fed between feed belts 16, Fig. 1 through a scanning station. Four images of the character are projected on. to a scanning device by lenses 36, one of the images being reversed by lens 38. The scanning device has four corresponding stations, two for horizontal and vertical registration and two for horizontal and vertical scanning. The four stations are placed at opposite ends of right angle diameters as shown in Fig. 3. The horizontal registration signal 28, Fig. 4 consists of a slit 46 in a rotating disc 40 and a wider slit 47 in the fixed disc 41. The arrival of the right hand edge of the character in the slit 46 causes a photo-cell 49 to produce a pulse. The vertical registration station 30, Fig. 6 is similar but has a slit 72 in disc 40 producing a pulse in photo-cell 73 when it encounters the bottom bar of the character. The horizontal scanning station Fig. 5 consists of a bank of ten parallel photo-conductors 60-69 and a slit 56 in the moving disc 40. Delay means produce, from the horizontal start pulse, pulses at the instants the slit 56 crosses the right and left vertical parts of the character so that at each of these times ten signals are available. Under the control of the vertical registration pulse the two photoconductors are chosen which correspond to upper and lower mid lines 22, 23, Fig. 8 so that signals are obtained indicating the presence or absence of points HUR, HLR, HUL, HLL. The vertical reading station 31, Fig. 7 consists of a fixed slit 76 and a slit 75 in the moving disc so that a single scan is taken down the centre line of the character, shown at 24 in Fig. 8. Under the control of the vertical registration pulse the signal is sampled at the instants corresponding to the horizontal bars so that signal representing the presence or absence of points VC and VU are obtained. Twelve signals representing the presence and absence of the six points VC, VU, HUL, HLL, HUR and HLR are gated together to detect the combinations of signals shown in Fig. 9 and signals are produced indicating the character recognised. The characters are designed so that each difference from any of the others by at least two bits. Where a combination occurs which is not recognised, owing to an error in one bit, an indication may be produced of which characters it may represent.