GB1492116A - Readers for punched cards - Google Patents

Abstract

1492116 Punched card reader SOC ITA. LIANA TELECOMUNICAZIONI SIEMENS SpA 28 Feb 1975 [21 March 1974] 8411/75 Heading G4M A punched card reader has a plurality of optical sensors LO arranged transverse to the direction of movement of the card and a plurality of optical sensors LV arranged parallel to the direction of movement of the card. The parallel sensors LV are spaced a distance h, equal to the spacing between columns on the punched card and the spacing h between the sensors LO and the first of the sensors LV is equal to the spacing between the leading edge of the card and the fitst column (Fig. 3, not shown). The card has a leading corner removed so that when a card is inserted into a slot of the reader to obscure the first of the parallel sensors LV an end one of the transverse sensors is not obscured and acts as a control sensors. This sensor is maintained activated in the waiting condition. The vertical sensors feed a NOR gate N, so that each time a sensor is obscured a pulse is fed to activate a counter CN1 which receives timing pulses CK to successively activate, via decoder DC1, transverse sensors LO. Data from each column on the card is fed to memory MM. After all sensors LO have been activated counter CN1 produces a pulse c which increments counter CN2 which, via decoder DC2 activates the next sensor of parallel sensors LV. When all columns have been read Logic Network RL produces a pulse g which clears counter CN2 such that the first sensor is again activated. If a card is fully removed during reading the counters are reset. If a card is partially removed reading does not commence until the activated sensor LV is obscured so that a column is not accidentally read twice.