GB949415A - - Google Patents

Abstract

949,415. Feeding webs. CROSFIELD ELECTRONICS Ltd. Nov. 23, 1962 [Nov. 24, 1961], No. 42140/61. Heading B6B. [Also in Division G3] In an arrangement for ensuring correct registration between a moving web 1 and a number of machines 2 . . . 4 in a multi-colour printing unit, pulses corresponding to the position of printing cylinders are recorded on a narrow strip of magnetic ink printed on the underside of the web at 7 and detected at reproducing heads 11, 12; variations in the time between these two events are detected by devices 14, 15 and used to adjust the path length between successive machines by vertical movement of rollers 5, 6. An impulse wheel 10 driven from the printing cylinders produces several pulses per revolution and the web length from recording to each reproducing head is preferably arranged to contain an exact number of recorded pulses when registration is correct so that the reproduced signals are in synchronism with those from the impulse wheel 10. Lack of synchronism, e.g. due to stretching of the web, results in a correcting signal to servomotors 16, 17, preferably derived in the manner described in Specification 641,830. The web is kept in tension by making each successive printing cylinder of slightly greater circumference than its predecessor and driving them all at the same speed.