Marking drop-outs in flexible magnetic tapes - by recording electronic marks in separate track as drop-outs are registered

摘要

In magnetic tape manufacture, so-called "drop-outs" may occur owing to dust or fibre on the surface or insufficient coating. These cause interference, e.g. horizontal lines on screens in the case of video tapes. The present arrangement makes marks electronically on a separate track of the tape by means of an audio head at the same time as the drop-out is registered by scanning the tape with a rotating head. The mark is made at a given distance from the drop-out and is subsequently located by a rotating magnetic head so that the drop-out can be evaluated by means of a microscope or magnifier.