Verfahren und Vorrichtung zur selbsttaetigen Filmpositionierung in Mikrofilm- und Rueckvergroesserungsgeraeten

摘要

Microfilm is transported past a read-out station. Each of the frame of the microfilm has a code markings in a cyclic progressive code. An optical read head furnishes code marking signals corresponding to the code marking of the frame at the microfilm read-out station. A keyboard furnishes an input signal signifying a selected frame. A first comparator compares the input signal to the code marking signal and furnishes a first coincidence signal when the two are equal. The first comparator further furnishes a comparator signal determining the direction of transport of the film in dependence on the sign of the difference between the code marking signal and the input signal. A second comparator compares each code marking signal with the last previously read code marking signal and furnishes a second coincidence signal when a unit step is indicated by said comparison. The film transport is stopped upon simultaneous presence of the first and second coincidence signals.