Patent GB-845050-A (GB)
Title: Improvements in or relating to statistical record sensing systems
IPC: G06F3/08
Filed: 1958-04-18
Abstract: 845,050. Statistical record card apparatus. SIEMENS & HALSKE A.G. April 18, 1938 [April 18, 1957], No. 12410/58. Class 106 (1). A record to be checked has data thereon recorded in such a way that during sensing a train of ten signal pulses is produced for each character read, one pulse in the train being unique, and there are reference marks on the record such that ten synchronizing pulses are produced for each train of signal pulses, and means are provided for counting coincidences between synchronizing pulses and ordinary data signals and for indicating if the number of coincidences is ten or eight. A digit is recorded by darkening the appropriate column position and the record 1, Fig. 1, is sensed photoelectrically by being moved past photo-cells 7, 9. Cell 7, receiving light from the synchronization column, and cell 9, receiving light from one of the record columns, are connected through amplifiers 10, 11, Fig. 2, each having two outputs, to gates 12, 14, 16 and 17. Gates 12 and 14 control triggers 13, 15 and gates 16, 17 supply pulses to counters 18 and 19, counter 18 having ten steps and counter 19 eleven. If the first record position (digit " 1 ") is not marked both amplifiers produce positive pulses on those outputs connected to gate 17, the third input of which is from trigger 15 normally providing a positive control voltage. Coincidence between white spaces thereby causes a pulse to pass through gate 17 to counter 19. Upon detection of a marked column position, trigger 15 is set by a signal through gate 12, trigger 13 and gate 14. Trigger 15 then applies a negative voltage to close gate 17, so that no more pulses can pass to counter 19, and a positive voltage to gate 16, which opens to allow subsequent coincidental pulses to pass to counter 18. Pulses before the detection of a column mark therefore pass to counter 19 and those after it pass to counter 18 so that the contents of these counters should be complements to nine, e.g. four in counter 19 and five in 18. The ten stages of the counters are gated together to determine whether the numbers held therein are complementary and if they are, one of the gates (e.g. 25) passes a pulse via Or gate 23 to gate 24 which passes the output of the tenth stage of a counter 20 to set trigger 26 (counter 20 receives the sync. pulses and registers ten at the end of the sensing operation). Trigger 26 allows the set stages of one or both counters 18, 19 to be transmitted as output signals via code converter 27. If no column position has been marked counter 19 will count up to ten, a signal from this stage setting an error trigger 28. If two positions are marked in the same column the counters 18, 19 do not hold complementary numbers, so that gate 23 continues to produce a negative signal which passes through gate 29 when counter 20 reaches ten and sets error trigger 30. In a simpler embodiment a counter is adapted to count all data pulses except the one corresponding to the marked position. At the receipt of this, the value in the counter is transferred to a data store. The sync. pulses are counted as before. A correct column causes the first counter to register nine and the sync. pulse counter to register ten. These stages are gated together and control read-out of the sensed data from the store. Errors are detected by means similar to those described in connection with Fig. 2. Specification 845,049 is referred to.