Sheet stacking apparatus and sheet processing apparatus equipped therewith

Abstract

A sheet stacking apparatus includes: a stacking tray which stacks a fold-processed and ejected sheet, and descends in response to a mass of stacked sheets; and a first sheet pressing member which holds the stacked sheets downward from an upper side of the stacked sheets at a constant height.

1 . A sheet stacking apparatus comprising:
 (a) a stacking tray which stacks a fold-processed and ejected sheet, and descends in response to a mass of stacked sheets; and   (b) a first sheet pressing member which holds the stacked sheets downward from an upper side of the stacked sheets at a constant height.   
     
     
         2 . The sheet stacking apparatus of  claim 1 , further comprising a spring which urges upward and holds the stacking tray. 
     
     
         3 . The sheet stacking apparatus of  claim 1 , wherein the first sheet pressing member guides downward the sheet being conveyed to the stacking tray. 
     
     
         4 . The sheet stacking apparatus of  claim 2 , wherein the stacking tray is pivotally supported at an edge portion of a downstream side in an ejection direction of the sheet, and is held and urged upward by the spring so as to be capable of moving up and down at an edge portion of an upstream side in the ejection direction. 
     
     
         5 . The sheet stacking apparatus of  claim 1 , wherein the first sheet pressing member comprises a rotary member which comes in contact with the sheet being conveyed and rotates according to movement of the sheet, and presses downward a trailing edge of the sheets in the ejection direction, which have been stacked on the stacking tray. 
     
     
         6 . A sheet stacking apparatus comprising:
 (a) a stacking tray which stacks a fold-processed and ejected sheet;   (b) a first sheet pressing member which presses a trailing edge of a sheet in an ejection direction of the sheet at a constant height; and   (c) a second sheet pressing member which presses a leading edge of the sheet on the stacking tray in the ejection direction of the sheet,   wherein the second sheet pressing member is supported by a stationary section at an edge on upstream side in the ejection direction of the sheet and an edge on downstream side of the second sheet pressing member in the ejection direction of the sheet is a free edge.   
     
     
         7 . The sheet stacking apparatus of  claim 6 , wherein the first sheet pressing member comprises a rotary member which comes in contact with the sheet being conveyed and rotates according to movement of the sheet. 
     
     
         8 . The sheet stacking apparatus of  claim 6 , wherein the first sheet pressing member guides downward the sheet being conveyed. 
     
     
         9 . The sheet stacking apparatus of  claim 6 , wherein the second pressing member is a sheet shaped member having an elastic characteristic. 
     
     
         10 . The sheet stacking apparatus of  claim 6 , wherein the stacking tray is pivotally supported at an edge portion of a downstream side in a conveyance direction of the sheet, and is urged upward by a spring at an edge portion of an upstream side in the conveyance direction. 
     
     
         11 . The sheet stacking apparatus of  claim 6 , wherein when the sheet is not stacked on the sheet stacking tray, the free edge of the second pressing member protrudes downward from the stacking tray. 
     
     
         12 . The sheet stacking apparatus of  claim 6 , wherein the second pressing member comprises a layer having a surface in contact with the sheet in which friction of the surface is adjusted, and a lining layer which enhances rigidity of the second pressing member. 
     
     
         13 . A sheet stacking apparatus for stacking a fold-processed and ejected sheet comprising:
 (a) a stacking tray which stacks a sheet;   (b) a third sheet pressing member which holds a sheet, which has been stacked on the stacking tray; and   (c) a control member which controls the third sheet pressing member,   wherein the control member selectively places the third sheet pressing member at either a pressing position where the third sheet pressing member presses the sheet or an retreated position where the third sheet pressing member has retreated from the sheet in response to at least one of a sheet size, a sheet type, and a type of fold processing.   
     
     
         14 . The sheet stacking apparatus of  claim 13 , wherein the third sheet pressing member comprises a leading edge stopper at which a leading edge of the sheet in an ejection direction hits. 
     
     
         15 . The sheet stacking apparatus of  claim 13 , wherein the third sheet pressing member comprises a sheet pressing section which presses downward the sheet stacked on the sheet stacking tray. 
     
     
         16 . The sheet stacking apparatus of  claim 14 , further comprising a trailing edge support wall which receives a trailing edge of the sheet stacked on the sheet stacking tray in the ejection direction, and the leading edge stopper is parallel with the trailing edge support wall. 
     
     
         17 . The sheet stacking apparatus of  claim 13 , wherein the control member places the third sheet pressing member at the pressing position when the sheet is ejected, and at the retreated position when the sheet is not ejected. 
     
     
         18 . The sheet stacking apparatus of  claim 13 , further comprising a first sheet pressing member which guides the sheet when ejecting the sheet to the sheet stacking tray, and presses downward a trailing edge of the sheets in the ejection direction, which have been stacked on the stacking tray. 
     
     
         19 . A sheet processing apparatus including a fold processing section which conducts a fold processing of a sheet, an ejection section which ejects a fold-processed sheet and a sheet stacking apparatus which stacks the sheet, which has been ejected from the ejection section, the sheet stacking apparatus comprising:
 (a) a stacking tray, which is capable of descending in response to a mass of stacked sheets, to which the fold process has been applied and ejected from the ejection section; and   (b) a sheet pressing member which presses the stacked sheets downward from an upper side of the stacked sheet at a constant height.   
     
     
         20 . The sheet processing apparatus of  claim 19 , wherein the ejection section comprises sheet ejection rollers formed by a pair of rollers, the first sheet pressing member comprises a rotary member which comes in contact with the sheet being conveyed and rotates according to movement of the sheet, and the rotary member is arranged so that a center of a rotation shaft of the rotary member is positioned in an upper side of an extended line from a nip formed by the sheet ejection rollers and a sheet pressing surface of the rotary member is positioned in a lower side of the extended line. 
     
     
         21 . A sheet processing apparatus including a fold processing section for conducting a fold processing of a sheet, ejection rollers constituted of a pair of rollers, an ejection section for ejecting a sheet processed by the fold processing section, and a sheet stacking apparatus for stacking a sheet ejected from the ejection section, the sheet finisher comprising:
 (a) a stacking tray which stacks a sheet, to which the fold process has been applied by the fold processing section and ejected from the ejection section;   (b) a first sheet pressing member which presses a trailing edge of the sheet in an ejection direction of the sheet at a constant height; and   (c) a second sheet pressing member which presses a leading edge of the sheet on the stacking tray in the ejection direction of the sheet,   wherein the second sheet pressing member is supported by a stationary section in an edge on upstream side in the ejection direction of the sheet and an edge on downstream side of the second sheet pressing member in the ejection direction of the sheet is a free edge.   
     
     
         22 . The sheet processing apparatus of  claim 21 , wherein the first sheet pressing member comprises a rotary member which comes in contact with the sheet being conveyed and rotates according to movement of the sheet, and the rotary member is arranged so that a center of a rotation shaft of the rotary member is positioned in an upper side of an extended line from a nip formed by the sheet ejection rollers and a sheet pressing surface of the rotary member is positioned in a lower side of the extended line.