Sheet treating apparatus and image forming apparatus therewith

Abstract

A sheet treating apparatus including a sheet discharging device for discharging a sheet, a first stacking tray for receiving the sheets discharged by the sheet discharging device, an aligning device for aligning a sheet bundle on the first stacking tray by a pinching movement effected by a first and second aligning members shiftable independently in a direction perpendicular to a sheet discharging direction, and a transferring device for transferring the sheet bundle on the first stacking tray to a second stacking tray, wherein, in the first stacking tray, alignment positions of the respective sheet bundles are offset by shifting the alignment positions by a predetermined amount to first and second aligning positions alternately by the first and second aligning members, and wherein the first and second aligning positions of the first stacking tray are opposite directions transverse to the sheet discharging direction with respect to the position of the sheet discharged.

What is claimed is: 
     
       1. A sheet treating apparatus including:
 sheet discharging means for discharging a sheet; 
 first stacking means for receiving the sheets discharged by said sheet discharging means; 
 aligning means for aligning the discharged sheets to be made into a sheet bundle on said first stacking means by a pinching movement effected by first and second aligning members shiftable independently in a sheet width-wise direction perpendicular to a sheet discharging direction; 
 stapling means shiftable along an end of the sheet bundle in said sheet width-wise direction and configured to staple the sheet bundle aligned by the aligning means on said first stacking means;  
 a plurality of driving means for driving said first and second aligning members independently; 
 controlling means for controlling said driving means; and 
 transferring means for transferring the sheet bundle on said first stacking means to a second stacking means, 
 wherein a first sheet bundle is aligned by using a first reference position obtained by shifting one of said first and second aligning members by a predetermined amount with respect to a lateral edge of the discharged sheet, and then a second sheet bundle is aligned by using a second reference position obtained by shifting the other aligning member by a predetermined amount with respect to a lateral edge of the discharged sheet, thereby the first sheet bundle and the second sheet bundle are made offset relative to each other, and such sheet bundle aligning operations are effected alternately for successive sheet bundles, and 
 said controlling means is adapted to control said stapling device so that said stapling device is moved to respective positions corresponding to said first and second alignment positions to perform a stapling operation. 
 
     
     
       2. A sheet treating apparatus according to  claim 1 , wherein, whenever several sheets in each sheet bundle are stacked on said first stacking means, said transferring means transfers the several sheets to said second stacking means. 
     
     
       3. A sheet treating apparatus according to  claim 1 , wherein, whenever all of the sheets in each sheet bundle are stacked on said first stacking means, said transferring means transfers said sheet bundle to said second stacking means. 
     
     
       4. A sheet treating apparatus according to  claim 3 , further including stapling means, and wherein each sheet bundle is stapled by said stapling means before the sheet bundle is transferred. 
     
     
       5. A sheet treating apparatus according to  claim 1 , wherein said second stacking means is disposed at a downstream side of said first stacking means and is liftable and lowerable. 
     
     
       6. A sheet treating apparatus according to  claim 5 , wherein said transferring means feeds out the sheet bundle on said first stacking means while nipping the sheet bundle between upper and lower rotary members. 
     
     
       7. A sheet treating apparatus according to  claim 6 , further including stapling means for stapling the sheet bundle on said first stacking means, and wherein said stapling means is shiftable along the end of the sheet in a sheet width-wise direction perpendicular to the sheet discharging direction. 
     
     
       8. A sheet treating apparatus according to claim  7  1, wherein the sheet bundle offset amount in a non-stapling mode is greater than the sheet bundle offset amount in a stapling mode. 
     
     
       9. A sheet treating apparatus according to  claim 1 , wherein said aligning means is operated every one sheet discharged. 
     
     
       10. A sheet treating apparatus according to  claim 1 , wherein said sheet treating apparatus has a first mode in which, whenever several sheets in each sheet bundle are stacked on said first stacking means, said transferring means transfers the several sheets to said second stacking means, and a second mode in which, whenever all of the sheets in each sheet bundle are stacked on said first stacking means, said transferring means transfers said sheet bundle to said second stacking means. 
     
     
       11. A sheet treating apparatus according to  claim 10 , further including stapling means, and wherein, in said second mode, each sheet bundle is stapled by said stapling means before the sheet bundle is transferred. 
     
     
       12. A sheet treating apparatus according to  claim 11 , wherein the sheet bundle offset amount in said first mode is greater than the sheet bundle offset amount in said second mode. 
     
     
       13. A sheet treating apparatus according to  claim 1 , wherein said respective aligning members have a rack and a pinion, so that rotation of a motor is converted into a linear movement. 
     
     
       14. An image forming apparatus including:
 a sheet treating apparatus according to any one of  claims 1  to 6 or 8 to  13 ; 
 image forming means for forming an image on the sheet; and 
 discharging means for discharging the sheet on which the image is formed by said image forming means to said sheet treating apparatus.