Patent ID: 9102116
Filing Date: 2015-08-11
Classification: B31F,B65H

Abstract:
1. A sheet creaser, comprising: a pair of folding rollers that folds a sheet set including at least one sheet by pressing the sheet set in a nip portion therebetween with a nip pressure while conveying the sheet set thereby making a crease on the sheet set; a folding plate that thrusts the sheet set in the nip portion between the folding rollers with an edge of the folding plate coming in contact with the sheet set where the sheet set is to be folded, the folding plate being arranged opposed to the folding rollers with respect to the sheet set; a re-pressing roller that receives a folded sheet set from the folding rollers and re-presses the sheet set by rolling along the crease thereby making the crease stronger; and a pressure releasing unit that performs a pressure releasing operation of releasing the nip pressure in the nip portion between the folding rollers when the re-pressing roller re-presses the crease, wherein the pressure releasing unit moves back and forth, via a pressure control member, along a straight line corresponding with a movement of the folding plate, the pressure control member releases the pressure from the nip between the pair of folding rollers by setting a pair of swing arms to a pressure-release position, the pair of swing arms are connected to a movable shaft that is located downstream in a sheet conveyance direction in which the respective swing arms are connected to the movable shaft via a pair of connection members, a range of movement of the movable shaft corresponds to a length of a guide hole in the pressure control member which is in a direction parallel to the movement of the folding plate, and controls a range of movement of the pair of swing arms, and the pressure releasing unit starts the pressure releasing operation after the re-pressing roller starts re-pressing the crease.