Patent GB-504719-A (GB)
Title: Improvements in or relating to optical means for reading printed, stencilled and like records
IPC: G06V10/88
Filed: 1937-10-26
Abstract: 504,719. Examining printed records; automatic control systems. BRITISH TABULATING MACHINE CO., Ltd. Oct. 26, 1937, Nos. 29213, 29214, and 29215. Convention dates, Oct. 27, 1936, Oct. 28, 1936, and Oct. 29, 1936. [Class 40 (iii)] [Also in Group XXXV] In a system for optically reading printed, stencilled, &c. records in which an image of the original character is compared with a standard character so as to obtain coincidence between the two when they are of a similar nature, the image of one character is formed in the plane of the other a number of times, each time in a different position relative to the second character, said positions being uniformly distributed in such manner that the image and second character are substantially in correct registration in one of the positions. In this way allowance is made for any incorrect positioning of the original. Light from lamp 13, Fig. 1, is projected through the character-bearing strip 11 at a point corresponding to slot 20. Behind this slot, in the form of an endless band, is an opaque mask 10, and behind this, is a photo-cell 12. The mask' bears translucent representations as shown in Fig. 3 each being repeated horizontally according to the number of columns to be read and five times vertically 25a-e in staggered formation to allow for horizontal displacement of the original characters. The mask makes one complete cycle for each line of characters in the original and each character must register in some position with a representation on the mask. When this occurs light is completely cut off from the photo-cell 12. A separate photo-cell is used for each column of figures and each is so connected that when no light falls on it a relay is operated and the resultant impulses are communicated to a counting machine of the Hollerith type or to an automatic typewriter. As each line is completed an electromagnet 18 operates feeding rollers 16 by means of a pawl 19 and ratchet wheel 17 to advance the record one line. In a modification, Fig. 5 (not shown), the mask is fixed in the form of an arc of a circle at the centre of which is the original and about which centre turns an arm carrying the photo-cells in such a way as to produce the necessary relative movement between the mask and original. Where the original is a printed record and the spacing is presumably correct only initial registry is necessary. For this purpose a mask as shown in Fig. 11 is used the central row being taken as the standard. If the original registers with one of the representations 81a-e other than the central one the mask is moved later-, ally to bring the central row into the correct position. For this purpose the mechanism shown in Fig. 9 is employed wherein a lead 90 is connected to the gas discharge relay 26 pertaining to the photo-cell 12 behind the first column of figures. This lead 90 is connected to a brush mechanism 88 rotating on the same shaft 23 as the mask drive and bearing on a commutator 84 divided into a number of groups of three segments the number of groups corresponding to the number of characters, in this case 1 to 9. If the first photo-cell is actuated before the correct central position is reached the impulse passes via the first of the three segments of the appropriate group to electromagnet 92. This operates a pawl 95 which, through gearing 96, turns a crank 97 through a small arc and by connection 98 moves the mask laterally in the required direction. If the photo-cell is actuated after the correct position is passed the pulse passes through the third segment to magnet 110. which causes a movement of crank 97 in the opposite direction. When the mask is correctly centred the pulses pass through the centre segments to the recording mechanism. Where only one column of figures has to be read the image of each figure in turn may be split up into five images by means of five prisms, Figs. 13, 14, (not shown). A photo-cell is placed behind each prism and a mask is interposed: This mask is moved relatively to the prisms and the five transverse representations are displaced slightly perpendicular to their direction of movement to allow for inaccuracies in the positioning of the original. Alternatively nine lenses, Fig. 18, (not shown), are used in combination with a mask similar to Fig. 3 moving relatively to them. An image of the same original is projected by each of the lenses on to each group of representations on the mask and by a relative, movement of the mask corresponding to the space covered by the five rows of figures one. image coincides in one case and the light cell appropriate to that figure is actuated.