Image generating apparatus with tension unit for adjusting tension of continuous paper

摘要

A laser printer capable of printing on a strip of fan fold paper includes a photosensitized drum for generating thereon a toner image to be transferred to the surface of the paper strip. The drum is associated with tractor assemblies operable in synchronism with the speed of the drum so as to determine travel speed of the paper strip passing by the drum. The laser printer further includes a fixing unit having a pair of fixing rollers for pressing the paper strip therebetween and a roller drive mechanism to drive the fixing rollers so as to determine travel speed of the paper strip passing through the fixing unit. A tension unit is disposed between the drum and the fixing unit for applying a tension to and thereby taking up slack of such portion of the paper strip that runs between the drum and the fixing unit. The tension unit includes a tensioning plate supported for pivotal motion and a helical tension spring for urging the tensioning plate. A sensing mechanism senses displacement of the tensioning plate. A control unit controls speed of the fixing rollers in an attempt to maintain displacement of the tensioning plate substantially at a desired level. The tension unit further includes an adjustment device for adjustment in the urging force to be applied by the spring to the tensioning plate.