Sheet stacking device and image forming apparatus

Abstract

A sheet stacking device includes a stacker, a conveyor, and a marking device. The stacker stacks transfer sheets. The conveyor conveys the transfer sheets toward the stacker in a sheet conveyance direction. The marking device includes a marker storage to store a marker, an ejection port to eject the marker, a marker conveyor to convey and eject the marker from the ejection port, and a guide to prevent the marker ejected from the ejection port from moving in a direction opposite to the sheet conveyance direction. The marking device places the marker on an uppermost sheet of each predetermined number of the transfer sheets on the stacker.

1 . A sheet stacking device comprising:
 a stacker to stack transfer sheets;   a conveyor to convey the transfer sheets toward the stacker in a sheet conveyance direction;   a marking device including:
 a marker storage to store a marker; 
 an ejection port to eject the marker; 
 a marker conveyor to convey and eject the marker from the ejection port; and 
 a guide to prevent the marker ejected from the ejection port from moving in a direction opposite to the sheet conveyance direction, 
   wherein the marking device is configured to place the marker on an uppermost sheet of each predetermined number of the transfer sheets on the stacker.   
     
     
         2 . The sheet stacking device according to  claim 1 ,
 wherein the guide extends to a position below the uppermost sheet in a vertical direction orthogonal to the sheet conveyance direction.   
     
     
         3 . The sheet stacking device according to  claim 1 ,
 wherein the stacker is movable in a vertical direction orthogonal to the sheet conveyance direction,   the guide is movable between an uppermost position and a lowermost position of the guide in the vertical direction in accordance with a vertical movement of the stacker,   the guide has, when the guide is at the lowermost position:   a lower end lower than the uppermost sheet; and   an upper end higher than the ejection port.   
     
     
         4 . The sheet stacking device according to  claim 3 ,
 wherein the guide has:   a plate having an L-shaped cross section having:
 a body having a slotted hole extending in a longitudinal direction of the guide; and 
 a guide portion connected to the body at right angle, and a lower end of the guide portion extending downward below the body; and 
   screws screwed into a side face of the marker storage through the slotted hole.   
     
     
         5 . The sheet stacking device according to  claim 4 ,
 wherein the stacker includes a sheet tray having a sheet placement surface to place the transfer sheets on the sheet placement surface, and   the lower end of the guide portion contacts the sheet placement surface of the stacker.   
     
     
         6 . The sheet stacking device according to  claim 3 ,
 wherein the guide has:   a plate having an L-shaped cross section having:
 a body extending in a longitudinal direction of the guide; 
 a guide portion connected to the body at right angle, and a lower end of the guide portion extending downward below the body; and 
 a support having a hole and fixed to a bent portion between the body and the guide portion; and 
   a support pin fitted into the hole of the support and fixed to the marker storage to support the plate movable in the vertical direction.   
     
     
         7 . The sheet stacking device according to  claim 6 ,
 wherein the stacker includes a sheet tray having a sheet placement surface to place the transfer sheets on the sheet placement surface, and   the lower end of the guide portion contacts the sheet placement surface of the stacker.   
     
     
         8 . The sheet stacking device according to  claim 1 , further comprising:
 an air blower to blow an air to the transfer sheets conveyed to the stacker,   wherein the marking device further includes another guide facing the guide across the ejection port to prevent the marker ejected from the ejection port from moving in the sheet conveyance direction.   
     
     
         9 . The sheet stacking device according to  claim 8 ,
 wherein the stacker is movable in a vertical direction orthogonal to the sheet conveyance direction,   the guide and said another guide are movable in the vertical direction in accordance with a vertical movement of the stacker,   a lower portion of the guide and another lower portion of said another guide are inclined with respect to the vertical direction, and   a distance between the lower portion and said another lower portion increases downward.   
     
     
         10 . The sheet stacking device according to  claim 8 ,
 wherein the stacker is movable in a vertical direction orthogonal to the sheet conveyance direction,   the guide and said another guide are movable in the vertical direction in accordance with a vertical movement of the stacker,   the air blower stops blowing the air before the stacker starts moving downward, and   the air blower starts blowing the air after the stacker finishes moving upward.   
     
     
         11 . An image forming apparatus comprising:
 the sheet stacking device according to  claim 1 ; and   an image forming device disposed upstream from the sheet stacking device in the sheet conveyance direction to form images on the transfer sheets.