DEVICE FOR COMPENSATING FOR THE OFFSET OF A SHEET ELEMENT ON ROLLERS, IN PARTICULAR FOR A POSTER BOARD HAVING MOVING POSTERS

摘要

ABSTRACTThe device compensates for the offset of a sheet elementwhich is movably mounted on at least two parallel rollers which arealternately supply and receiving rollers. At least one (1) of theserollers is inclinable relative to the other and is controlled by means(17-20) for detecting the offset of the sheeet element and acting oncompensating means (3-12) which modify the angle of the inclinable roller-This device comprises an offset compensating member (3) which normallyrotates with the inclinable roller when the sheet element is correctlycentred. The rotation of the compensating member is temporarily inter-rupted and converted into a linear displacement by the action of atleast one abutment (9) which is shifted by the detecting means when thelatter detects an offset of the sheet element. The compensating meanscooperates, in its linear displacement, with the profile of a cam (12)which modifies the position of one end of the inclinable roller andconsequently the angle of the latter.The invention is applicable to the control of the offsetof any element in the form of a sheet or band held taut on two rollersor reels.