Sheet discharge device and sheet discharge method

Abstract

A sheet discharge device includes a sheet discharge roller pair composed of an upper roller and a lower roller; and a placement tray, arranged below the sheet discharge roller pair, configured to place a sheet discharged from the sheet discharge roller pair. The device further includes a sheet presser configured to be held on a sheet discharge side of the upper roller in a movable manner and pushed up by a sheet front end to be discharged, and depress a sheet rear end with the dead weight thereof after the sheet rear end passes through a nip between the sheet discharge roller pair. The device additionally includes an auxiliary tray that is movable between a first position where the sheet rear end depressed by the sheet presser is caught and a second position where the sheet rear end is released from the sheet presser.

What is claimed is: 
     
         1 . A sheet discharge device, comprising:
 a sheet discharge roller pair comprising an upper roller and a lower roller;   a placement tray, arranged below the sheet discharge roller pair, configured to place a sheet discharged from the sheet discharge roller pair;   a sheet presser configured to be held on a sheet discharge side of the upper roller in a movable manner and pushed up by a sheet front end to be discharged, and to depress a sheet rear end with a load of the sheet presser, after the sheet rear end passes through a nip between the sheet discharge roller pair; and   an auxiliary tray movable between a first position where the sheet rear end depressed by the sheet presser is held and a second position where the sheet rear end is released from the sheet presser.   
     
     
         2 . The sheet discharge device according to  claim 1 , wherein
 the sheet presser is arranged at a position where the upper roller and the lower roller abut against each other.   
     
     
         3 . The sheet discharge device according to  claim 1 , wherein
 a brake region having frictional resistance is formed on at least a part of the auxiliary tray.   
     
     
         4 . The sheet discharge device according to  claim 1 , further comprising:
 a sheet discharge sensor arranged on a conveyance upstream side with respect to the sheet discharge roller pair; and   an auxiliary tray driving mechanism configured to move the auxiliary tray, wherein   the auxiliary tray driving mechanism is configured to move the auxiliary tray to a predetermined position when the sheet discharge sensor detects passing of a sheet rear end.   
     
     
         5 . The sheet discharge device according to  claim 4 , wherein
 the auxiliary tray driving mechanism is configured to retract the auxiliary tray from the predetermined position when the sheet discharge sensor detects passing of a sheet front end of a succeeding sheet.   
     
     
         6 . The sheet discharge device according to  claim 4 , wherein
 one end of the auxiliary tray is fixed to a rotating shaft, and   the auxiliary tray driving mechanism is configured to rotate the auxiliary tray by controlling a rotation angle of the rotating shaft.   
     
     
         7 . The sheet discharge device according to  claim 4 , wherein
 the auxiliary tray driving mechanism is configured to move the auxiliary tray in a substantially horizontally direction.   
     
     
         8 . The sheet discharge device according to  claim 1 , wherein
 a wall surface of the placement tray is arranged on a conveyance upstream aide with respect to an outer shape of the sheet discharge roller pair.   
     
     
         9 . The sheet discharge device according to  claim 3 , wherein
 the brake region comprises at least one of a rubber material, a cork material, a felt material, a foaming material, or an embossed surface provided on the auxiliary tray.   
     
     
         10 . A sheet discharge method, including:
 pushing up a sheet presser movably held on sheet discharge side of an upper roller by a sheet front end discharged from a sheet discharge roller pair comprising the upper roller and a lower roller;   depressing a sheet rear end with a load of the sheet presser after the sheet rear end passes through a nip between the sheet discharge roller pair;   catching the sheet rear end depressed by the sheet presser with an auxiliary tray when the auxiliary tray is moved to a first position;   releasing the sheet rear end from the sheet presser by moving the auxiliary tray to a second position; and   dropping the sheet onto a placement tray having a wall surface arranged below the sheet discharge roller pair on a conveyance upstream side.   
     
     
         11 . The sheet discharge method according to  claim 10 , further comprising arranging the sheet presser at a position where the upper roller and the lower roller abut against each other. 
     
     
         12 . The sheet discharge method according to  claim 10 , further comprising forming a brake region having frictional resistance on at least a part of the auxiliary tray. 
     
     
         13 . The sheet discharge method according to  claim 10 , further comprising
 sensing a sheet discharge via a sensor provided on a conveyance upstream side with respect to the sheet discharge roller pair;   driving the auxiliary tray mechanism to move using an auxiliary tray driving mechanism; and   causing the auxiliary tray mechanism to move the auxiliary tray to a predetermined position when the sensor detects passing of a sheet rear end.   
     
     
         14 . The sheet discharge method according to  claim 13 , further comprising
 retracting the auxiliary tray from the predetermined position when the sensor detects passing of a sheet front end of a succeeding sheet.   
     
     
         15 . The sheet discharge method according to  claim 13 , further comprising
 fixing one end of the auxiliary tray to a rotating shaft, and   causing the auxiliary tray to rotate by controlling a rotation angle of the rotating shaft.   
     
     
         16 . The sheet discharge method according to  claim 13 , further comprising
 moving the auxiliary tray in a substantially horizontally direction.   
     
     
         17 . The sheet discharge method according to  claim 10 , wherein
 a wall surface of the placement tray is arranged on a conveyance upstream side with respect to an outer shape of the sheet discharge roller pair.   
     
     
         18 . The sheet discharge method according to  claim 12 , further comprising:
 forming the brake region by attaching at least one of a rubber material, a cork material, a felt material, or a foaming material to the auxiliary tray, or creating an embossed surface on the auxiliary tray.   
     
     
         19 . The sheet discharge method according to  claim 13 , further comprising
 retracting the auxiliary tray from the predetermined position after elapse of a predetermined time.