Post-processing apparatus and image forming system

Abstract

A post-processing apparatus includes a post-processing unit performing post-processing for a sheet ejected from a former-stage apparatus, a post-processing time calculating unit calculating a time required for the post-processing based on a content of the post-processing, a time comparing unit comparing the time required for the post-processing and a sheet interval between sheets ejected from the former-stage apparatus, an overlapping conveying unit overlapping a plurality of sheets ejected from the former-stage apparatus and conveying the overlapping sheets on an upstream side of the post-processing unit, and a control unit controlling the overlapping conveying unit, wherein the control unit changes the number of overlapping sheets in the overlapping conveying unit in accordance with the sheet interval of sheets ejected from the former-stage apparatus where the time required for the post-processing is determined to exceed the sheet interval based on a comparison result of the time comparing unit.

1 . A post-processing apparatus comprising:
 a post-processing unit to perform post-processing for a sheet ejected from a former-stage apparatus;   a post-processing time calculating unit to calculate a time required for the post-processing based on a content of the post-processing;   a time comparing unit to compare the time required for the post-processing and a sheet interval between sheets ejected from the former-stage apparatus with each other;   an overlapping conveying unit to overlap a plurality of sheets ejected from the former-stage apparatus and convey the overlapping sheets on an upstream side of the post-processing unit; and   a control unit to control the overlapping conveying unit,   wherein the control unit changes the number of overlapping sheets in the overlapping conveying unit in accordance with the sheet interval of sheets ejected from the former-stage apparatus in a case where the time required for the post-processing is determined to exceed the sheet interval based on a comparison result of the time comparing unit.   
     
     
         2 . The post-processing apparatus according to  claim 1 , wherein the control unit changes the number of overlapping sheets in the overlapping conveying unit in accordance with the sheet interval of the sheets ejected from the former-stage apparatus at the time of maintaining same set in the plurality sets for printing in an image forming apparatus arranged on a former stage of the post-processing apparatus. 
     
     
         3 . The post-processing apparatus according to  claim 1 , wherein the control unit changes the number of overlapping sheets in the overlapping conveying unit in accordance with the sheet interval of the sheets ejected from the former-stage apparatus at the time of occurring different set in the plurality sets for printing in an image forming apparatus arranged on a former stage of the post-processing apparatus. 
     
     
         4 . The post-processing apparatus according to  claim 1 , wherein the control unit performs control of ejecting the sheets overlapped each other in the overlapping conveying unit toward the post-processing unit in a case where the post-processing unit disposed on a downstream side of the overlapping conveying unit is in a state in which sheets can be received. 
     
     
         5 . The post-processing apparatus according to  claim 4 , wherein the control unit determines the state in which sheets can be received based on whether or not the post-processing for sheets sent to the post-processing unit in advance has been completed. 
     
     
         6 . The post-processing apparatus according to  claim 4 , wherein the control unit determines the state in which sheets can be received based on whether or not a predetermined time has elapsed after a final sheet is sent to the post-processing unit for the post-processing. 
     
     
         7 . The post-processing apparatus according to  claim 1 , wherein the former-stage apparatus is an image forming apparatus. 
     
     
         8 . The post-processing apparatus according to  claim 1 , wherein the former-stage apparatus includes a different type of a post-processing apparatus that has a post-processing unit other than the post-processing unit. 
     
     
         9 . An image forming system comprising:
 an image forming apparatus to form an image and transfer the image to the sheet;   a post-processing apparatus being located on a later stage side of the image forming apparatus and including a post-processing unit to perform post-processing for a sheet ejected from a former-stage apparatus and an overlapping conveying unit to overlap a plurality of sheets ejected from the former-stage apparatus and convey the overlapping sheets on an upstream side of the post-processing unit;   a post-processing time calculating unit to calculate a time required for the post-processing based on a content of the post-processing;   a time comparing unit to compare the time required for the post-processing and a sheet interval between sheets ejected from the former-stage apparatus of the post-processing apparatus with each other; and   the control unit according to  claim 1 .   
     
     
         10 . The image forming system according to  claim 9 , wherein at least one of a different type of a post-processing apparatus having a post-processing unit other than the post-processing unit is connected in sequence to the former stage of the post-processing apparatus in a later stage side of the image forming apparatus.