Synchronized document reader

Claim 1

APPARATUS FOR SYNCHRONOUSLY READING OUT PRINTED BAR CODE DATA FROM A DOCUMENT, COMPRISING A READOUT STATION, A FEED DRUM, MEANS COOPERATING WITH SAID FEED DRUM TO RETAIN A DOCUMENT THEREAGAINST, MEANS FOR ROTATING SAID FEED DRUM TO MOVE SUCCESSIVE DOCUMENTS PAST SAID READ STATION, MEANS FOR MECHANICALLY SENSING THE PRESENCE OF EACH DOCUMENT PRIOR TO ITS ARRIVAL AT SAID READ STATION, MEANS RESPONSIVE TO SAID SENSING MEANS FOR DERIVING A CONTROL SIGNAL FOR THE DURATION OF SAID DOCUMENT OF SAID READ STATION, SAID READOUT STATION INCLUDING A FIRST LIGHT SOURCE FOR ILLUMINATING SAID BAR CODE, A PHOTOELECTRIC READING HEAD FOR SCANNING SAID ILLUMNATED BAR CODE TO DERIVE CORRESPONDING READOUT SIGNALS, A SLIP CLUTCH COAXIALLY FAST WITH SAID DRUM, A TOOTHED TIMING DISC INCLUDING RADIAL SLOTS WITH A CENTER-TO-CENTER SPACING CORRESPONDING TO THAT OF SAID CODE BARS, A SECOND LIGHT SOURCE DISPOSED ON ONE SIDE OF SAID TIMING DISC, PHOTOELECTRIC SENSING MEANS DISPOSED ON THE OTHER SIDE OF SAID TIMING DISC IN LINE WITH SAID SECOND LIGHT SOURCE AND SAID SLOTS TO GENERATE TIMING PULSES CORRESPONDING TO SAID SLOTS, A PAWL NORMALLY URGED INTO ENGAGEMENT WITH THE TEETH OF SAID TIMING DISC TO LOCK THE LATTER AGAINST ROTATION WITH SAID CLUTCH, AND A SOLENOID RESPONSIVE DURING THE PRESENCE OF SAID CONTROL SIGNAL TO DISENGAGE SAID PAWL FROM SAID TIMING DISC.