Sheet conveying device and image processing apparatus

Abstract

A sheet conveying device includes a tray, an elevating mechanism, a conveyance roller, and a resistance member. The tray stacks a plurality of sheets. The elevating mechanism lifts and lowers the tray in the stacking direction of a plurality of sheets. The conveyance roller conveys the plurality of sheets in the conveyance direction from the upper side in the stacking direction. The resistance member comes into contact with the leading ends of the plurality of sheets in the conveyance direction. The resistance member imparts a sliding resistance larger than that of the sheet stacking surface of the tray to the leading ends of the plurality of sheets that are lifted and lowered by the elevating mechanism.

What is claimed is: 
     
         1 . A sheet conveying device, comprising:
 a tray configured to accommodate a stack of a plurality of sheets;   an elevating mechanism configured to lift and lower the tray in a stacking direction of the plurality of sheets;   a conveyance roller configured to convey one sheet at a time from the plurality of sheets in the conveyance direction from the upper side in the stacking direction;   a resistance member in contact with a leading end of the plurality of sheets in the conveyance direction and configured to impart a sliding resistance larger than a sliding resistance of a sheet stacking surface of the tray to the leading ends of the plurality of sheets that are lifted and lowered by the elevating mechanism; and   an actuator configured to rotate when pushed by a leading end of the sheet, wherein   the resistance member arranged on both sides of a conveyance center line in the sheet transfer device, and the actuator located between the resistance member arranged on both sides of the conveyance center line.   
     
     
         2 . The device according to  claim 1 , wherein
 the resistance member comprises a surface layer portion that comes into contact with the plurality of sheets and the surface layer portion is non-smooth in the stacking direction.   
     
     
         3 . The device according to  claim 2 , wherein
 the resistance member has a napped material comprising a plurality of fibers extending toward the plurality of sheets on the surface layer portion.   
     
     
         4 . The device according to  claim 1 , wherein
 the resistance member has a surface in contact with the plurality of sheets and the surface has a friction coefficient larger than a friction coefficient of the sheet stacking surface.   
     
     
         5 . The device according to  claim 1 , wherein
 the resistance member has conductivity.   
     
     
         6 . The device according to  claim 1 , wherein
 the elevating mechanism lifts and lowers the tray between a first lowered position where the plurality of sheets is set and a lifted position above the first lowered position in the stacking direction and capable of abutting upper ends of the plurality of sheets against the conveyance roller, and   the resistance member is arranged at a position contacting the leading end of the plurality of sheets in at least a part of the elevating range of the tray.   
     
     
         7 . The device according to  claim 6 , wherein
 the elevating mechanism configured to descend to a second lowered position located below the first lowered position in the stacking direction and move the tray from the second lowered position toward the lifted position.   
     
     
         8 . The device according to  claim 1 , wherein
 the tray stacks a first sheet bundle comprising a plurality of sheets so that the leading end of the first sheet bundle abuts the resistance member and the first sheet bundle can be lifted and lowered, and   the device further comprises   a moving tray configured to be movable between a first position in the direction opposite to the conveyance direction with respect to the tray and a second position on the upper side of the tray to place a second sheet bundle formed of a plurality of sheets, and   a moving mechanism configured to move the moving tray from the first position to the second position and place the second sheet bundle on the tray when the tray is descending by the elevating mechanism.   
     
     
         9 . The device according to  claim 6 , further comprising:
 a control circuit configured to control the conveyance roller and the elevating mechanism, wherein   the control circuit causes the elevating mechanism to lift and lower the tray at least once in an elevating range in which the plurality of sheets come into contact with the resistance member and then to move the tray to the lifted position, and then, drive the conveyance roller to start the conveyance of the plurality of sheets.   
     
     
         10 . An image processing apparatus, comprising:
 an image forming device; and   a sheet conveying device comprising:
 a tray configured to accommodate a stack of a plurality of sheets; 
 an elevating mechanism configured to lift and lower the tray in a stacking direction of the plurality of sheets; 
 a conveyance roller configured to convey one sheet at a time from the plurality of sheets in the conveyance direction from the upper side in the stacking direction; 
 a resistance member in contact with a leading end of the plurality of sheets in the conveyance direction and configured to impart a sliding resistance larger than a sliding resistance of a sheet stacking surface of the tray to the leading ends of the plurality of sheets that are lifted and lowered by the elevating mechanism; and 
 an actuator configured to rotate when pushed by a leading end of the sheet, wherein 
   the resistance member arranged on both sides of a conveyance center line in the sheet transfer device, and   the actuator located between the resistance member arranged on both sides of the conveyance center line.   
     
     
         11 . The apparatus according to  claim 10 , wherein
 the resistance member comprises a surface layer portion that comes into contact with the plurality of sheets and the surface layer portion is non-smooth in the stacking direction, the resistance member has a napped material comprising a plurality of fibers extending toward the plurality of sheets on the surface layer portion.   
     
     
         12 . The apparatus according to  claim 10 , wherein
 the resistance member has a surface in contact with the plurality of sheets and the surface has a friction coefficient larger than a friction coefficient of the sheet stacking surface.   
     
     
         13 . A sheet conveying method, comprising:
 lifting and lowering a tray configured to accommodate a stack of a plurality of sheets in a stacking direction of the plurality of sheets using an elevating mechanism;   conveying one sheet at a time from the plurality of sheets in the conveyance direction from the upper side in the stacking direction;   contacting a resistance member with a leading end of the plurality of sheets in the conveyance direction and imparting a sliding resistance larger than a sliding resistance of a sheet stacking surface of the tray to the leading ends of the plurality of sheets that are lifted and lowered by the elevating mechanism; and   rotating an actuator when pushed by a leading end of the sheet, wherein   the resistance member arranged on both sides of a conveyance center line in the sheet transfer device, and   the actuator located between the resistance member arranged on both sides of the conveyance center line.   
     
     
         14 . The method according to  claim 13 , wherein
 the resistance member comprises a surface layer portion that comes into contact with the plurality of sheets and the surface layer portion is non-smooth in the stacking direction.   
     
     
         15 . The method according to  claim 14 , wherein
 the resistance member has a napped material comprising a plurality of fibers extending toward the plurality of sheets on the surface layer portion.   
     
     
         16 . The method according to  claim 13 , wherein
 the resistance member has a surface in contact with the plurality of sheets and the surface has a friction coefficient larger than a friction coefficient of the sheet stacking surface.   
     
     
         17 . The method according to  claim 13 , further comprising:
 lifting and lowering the tray between a first lowered position where the plurality of sheets is set and a lifted position above the first lowered position in the stacking direction and abutting upper ends of the plurality of sheets against the conveyance roller; and   contacting the leading end of the plurality of sheets in at least a part of the elevating range of the tray.   
     
     
         18 . The method according to  claim 17 , further comprising:
 descending the elevating mechanism to a second lowered position located below the first lowered position in the stacking direction and moving the tray from the second lowered position toward the lifted position.   
     
     
         19 . The method according to  claim 13 , wherein
 the tray stacks a first sheet bundle comprising a plurality of sheets so that the leading end of the first sheet bundle abuts the resistance member and the first sheet bundle can be lifted and lowered, and further comprising:   moving a moving tray between a first position in the direction opposite to the conveyance direction with respect to the tray and a second position on the upper side of the tray to place a second sheet bundle formed of a plurality of sheets; and   moving the moving tray from the first position to the second position and placing the second sheet bundle on the tray when the tray is descending.   
     
     
         20 . The method according to  claim 17 , further comprising:
 lifting and lowering the tray at least once in an elevating range in which the plurality of sheets come into contact with the resistance member and then moving the tray to the lifted position, and then, driving the conveyance roller to start the conveyance of the plurality of sheets.