Patent GB-793906-A (GB)
Title: Improvements in electrical comparing devices for recordí¡í¡ controlled machines
Filed: 1956-07-19
Abstract: 793,906. Statistical apparatus. MAUL, M. July 19, 1956 [Aug. 26, 1955], No. 22445/56. Class 106 (1). Means for comparing successive record cards at two sensing stations comprise a row of sensing brushes at each station, the two cards being fed past the brushes index point by index point, the two rows of brushes being at any time on the same index rows of the two cards, and the brushes in each row sensing corresponding columns of the two cards being successively connected in pairs to electrical comparing means. The cards in the two sensing positions remain with each index row under the sensing brushes for a time sufficient to allow a selector switch arm L, Fig. 3, to rotate from position 1 to position 9. This switch connects in turn pairs of sensing brushes, as determined by plug connections, to the comparing means which in this form consist of a differentially wound relay G. When each brush of a pair detects a hole in its respective card current flows from the contact plates P<SP>1</SP>, P<SP>2</SP> through the brushes B<SP>1</SP>, B<SP>2</SP>, through corresponding contacts of the switch and through both windings of the relay G. Since the windings are opposed the relay does not pick up. Where neither brush detects a hole, no current flows through the relay windings and, accordingly, it does not pick-up. But where one brush only of a pair detects a hole current flows through one winding only of the relay and it picks up. Contact g of relay G causes relay S to be energized to indicate disagreement between the cards. Instead of a single differentially wound relay G a pair of relays P<SP>1</SP>, p<SP>2</SP>, Fig. 4, may be used. The perforation code is such that a perforation in a higher position means a character of higher value, i.e. a digit or a letter later in the alphabet. Contacts of the relays P<SP>1</SP>, P<SP>2</SP> are connected so that an indication is given of whether the card values detected are equal to or greater or less than each other. Where each brush of a pair senses a hole both relays P<SP>1</SP>, P<SP>2</SP> respond so that contacts P<SP>1</SP>II and p<SP>2</SP>II open while contacts P<SP>1</SP>I and P<SP>2</SP>I close and neither of relays S<SP>1</SP>, S<SP>2</SP> pick-up. Where the left hand brush only detects a hole, relay P<SP>2</SP> picks up, closing contact P<SP>2</SP>I and opening P<SP>2</SP>II, thereby picking up self-holding relay S<SP>2</SP>. Contact S<SP>2</SP>III transfers to indicate that the following card has a lower group number than the preceding one. The relay S<SP>2</SP> remains energized until cam contact-n<SP>1</SP> opens at the end of the cycle, open contact S<SP>2</SP>II preventing energization of the relay S<SP>1</SP> during the rest of the cycle. In a modification the relays P<SP>1</SP> P<SP>2</SP> are replaced by a pair of thyratrons, one or the other of which is fired when one only of the pair of brushes detects a perforation. These in turn control relays S<SP>1</SP> S<SP>2</SP> having contacts indicating whether the following card is of higher, lower or equal value to the preceding one. The comparator may be used for group control of a machine or for verifying cards being punched in a reproducing punch.