Patent ID: 8186677
Filing Date: 2012-05-29
Classification: B65H

Abstract:
1. A sheet stacking device, comprising: an upper stacking portion and a lower stacking portion, the lower stacking portion provided under the upper stacking portion, said upper stacking portion and said lower stacking portion mounted for ascending and descending movement, and on which sheets delivered from a sheet delivery portion are stacked; a drive portion which is configured to drive the upper stacking portion and the lower stacking portion to ascend and descend; a connecting portion which is provided between the upper stacking portion and the drive portion, and configured to connect the upper stacking portion and the drive portion to each other; a descent stop portion which is configured to stop a self-weight descent of the upper stacking portion in a state where the connecting portion is disconnected from the drive portion; a sheet detection sensor which detects whether or not sheets are stacked on the lower stacking portion; a position detection sensor which detects whether or not the lower stacking portion is in a movable region which is under the sheet delivery portion and in which the upper stacking portion is descendible; and a control portion which controls the drive portion, the connecting portion and the descent stop portion based on a detection result of the sheet detection sensor and the position detection sensor; wherein the lower stacking portion is directly connected with the drive portion and always ascendible and descendible, in a case that the upper stacking portion is moved from a standby position which is above the sheet delivery portion to a receiving position at which sheets delivered from a sheet delivery portion are received and where the lower stacking portion is detected in the movable region by the position detection sensor, the control portion causes the connecting portion to connect the upper stacking portion and the drive portion, causes the disengagement of the descent stop portion, and causes the drive portion to move the upper stacking portion to the receiving position by integrally moving the upper stacking portion and the lower stacking portion, in a case that the upper stacking portion is moved from the standby position to the receiving position, where the lower stacking portion is not detected in the movable region by the position detection sensor and the stacked sheet on the lower stacking portion is not detected by the sheet detection sensor, the control portion causes the connecting portion to connect the upper stacking portion and the drive portion after raising the lower stacking portion to a predetermined position in the movable region by the drive portion and causes the upper stacking portion to move to the receiving position by integrally lowering the upper stacking portion and the lower stacking portion by the drive portion after disengaging the descent stop portion, and in a case that the upper stacking portion is moved from the standby position to the receiving position and where the lower stacking portion is not detected in the movable region by the position detection sensor and the sheet stacked on the lower stacking portion is detected by the sheet detection sensor, the control portion does not cause driving of the drive portion.