Apparatus for correcting zigzag motion of an elongated traveling web.

摘要

An apparatus for correcting zigzag motion of a longitudinally traveling elongate sheet (S) includes a feed forward sensor (FFS) on the travel path of the sheet and a feed forward correction mechanism (3) which is on the downstream side of, and is controlled by an open-loop method according to output signals from, this feed forward sensor to quickly correct the lateral displacement of the sheet. A feedback correction mechanism (9,10) on the downstream side is controlled by output signals from a feedback sensor (FBS) disposed further downstream thereto to correct by a closed-loop method the error in the correction effected by the first correction mechanism. If a significant trend of the sheet to move laterally in one direction is detected, parameters in the algorithm used by the feed forward correction mechanism are adjusted. <IMAGE>