Patent GB-717686-A (GB)
Title: Improvements in or relating to devices for comparing recorded data
IPC: G06F7/02
Filed: 1951-07-17
Abstract: 717,686. Statistical apparatus. COMPAGNIE DES MACHINES BULL July 17, 1951 [July 19, 1950], No. 16976/51. Class 106 (1) A device for comparing data represented by coded marks in columns of one or more record cards or strips comprises means for simultaneously projecting images of groups of card or strip columns on to image plates of two cathode-ray tubes, means for scanning the two images simultaneously by the C.R.T. beams and for producing an electric signal whenever a beam passes the image of a marking, and a comparing unit into which the signals from both tubes are introduced. This unit may be adapted to assume different equilibrium states according to the relative values of two compared numbers (high, low or equal). In the collating machine illustrated in Fig. 1, primary and secondary record cards P, S are fed to positions 601 in which images of the required fields are projected on to plates such as 603 of similar Iconoscope-type cathode-ray tubes. The horizontal and vertical beam deflections are determined by voltages supplied from amplifiers 613, 627 to plates such as 606, 608 respectively, the opposite deflecting plates 605, 607 being connected to field-selecting potentiometer P1 and potentiometer P2. The outputs of 613, 627 vary according to the amount of light supplied through transparent parts H, V of discs 611, 618 and slots such as 612 to photo-cells (not shown). The disc 611 is rotated once per machine, cycle through gearing 616 from the main shaft 615, and the part H is of stepped form to provide a constant voltage, Fig. 4(b), while a card column is being vertical scanned as indicated in Fig. 5, and a column-stepping voltage during the fly-back period. The disc 618 is rotated at a faster rate, through gearing 620, to cause one of the ten similar parts V to pass the amplifier slot for every step of part H to produce a scanning voltage of saw-tooth form, Fig. 4(a). For each image of a card marking (see Fig. 5) scanned, a pulse appears on a resistance such as 610 and is sent over a line 628 to the comparison circuit amplifier IS or IP, Fig. 2, to produce a negative pulse at output 630. A pulse from IS is supp!ied directly to the control grid of coincidence valve GP and through inverting stage AIS to the screen grid. of coincidence valve GS, similar connections being provided from IP. Thus, if two pulses appear on the two lines 628 simultaneously, valves GS, GP will have simultaneous negative and positive pulses applied thereto and the anode outputs will remain unchanged. If, however, a pulse is applied to IS only, for example, the resultant positive pulse on the screen grid of GS will produce a negative anode pulse which will switch over a two-state trigger circuit BS, comprising a pair of crossconnected triodes (Fig. 3, not shown), to the " 1 " state in which it applies a relatively high potential to the control grid of a valve VS. If, subsequently, a pulse is applied to IP only, trigger BP will be actuated and will apply a high potential to valve VP and a resetting pulse over line 649 to BS. With the scanning system indicated in Fig. 5 (lowest digit scanned first) the trigger (BP or BS) in the " 1 " state when the comparison has been completed will correspond to the higher number and will cause a corresponding relay 650 or 651 to be energized when cam contacts CGI close to apply a positive pulse to the screen grids of VP, VS. Relay 654 or 655 is then energized through contacts 650a or 651a and held through cam contacts CG2, and operates contacts 654b or 655b to energize relay 657 or 658 through cam contacts CG3. If the compared numbers are equal so that neither trigger is in the " 1 " state, none of the relays 650, 651, 654. 655 will be energized and a third relay 656 will be operated through CG3. The relays 656-658 may control the card feed through clutches 623, Fig. 1, or effect other operations, e.g. as described in Specification 636,911.The positive pulse from CG1, Fig. 2, passes also.through delay circuits 659, 660, to reset: triggers BS, BP. A modified circuit (Fig. 6, not shown) is described for effecting comparison where the highest digit is scanned first; in which the first trigger to be actuated prevents the. transmission of subsequent non-simultaneous triggering impulses. A binary numerical coding may replace that indicated in Fig. 5. Reference has been directed by the Comptroller to Specification 595,556.