Post-processing apparatus

Abstract

When performing post-processing on a preceding sheet of a recording medium stacked on a processing tray, a control portion arranges a first discharge roller and a second discharge roller in an apart position, and when the leading end of a subsequent sheet of the recording medium conveyed along a conveyance passage passes between the first and second discharge rollers and the trailing end reaches a branch point between the conveyance passage and the retraction passage, the control portion rotates a pair of intermediate conveyance rollers to retract the subsequent recording medium into a retraction passage.

What is claimed is: 
     
         1 . A post-processing apparatus, comprising:
 a processing tray;   a post-processing portion that performs post-processing on a recording medium stacked on the processing tray;   a conveyance passage that extends toward the processing tray;   a pair of intermediate conveyance rollers that conveys the recording medium along the conveyance passage toward the processing tray;   a retraction passage provided at a position different from the conveyance passage, the retraction passage extending toward the pair of intermediate conveyance rollers;   a pair of discharge rollers that discharges the recording medium on the processing tray to a discharge port;   a control portion that controls operation of the post-processing portion, the pair of intermediate conveyance rollers, and the pair of discharge rollers;   wherein   the pair of discharge rollers is composed of a first discharge roller and a second discharge roller,   the first and second discharge rollers is movable between a nip forming position, in which they form a nip portion by making contact with each other, and an apart position, in which they are apart from each other, and   when performing post-processing on a preceding sheet of the recording medium stacked on the processing tray, the control portion arranges the first and second discharge rollers in the apart position, and   when the leading end of a subsequent sheet of the recording medium conveyed along the conveyance passage passes between the first and second discharge rollers and the trailing end reaches a branch point between the conveyance passage and the retraction passage, the control portion rotates the pair of intermediate conveyance rollers to retract the subsequent sheet of the recording medium into the retraction passage.   
     
     
         2 . The post-processing apparatus according to  claim 1 , wherein
 an amount of opening between the first and second discharge rollers arranged in the apart position is larger than a thickness of a maximum number of sheets of the recording medium that the post-processing portion can perform post-processing on.   
     
     
         3 . The post-processing apparatus according to  claim 1 , wherein
 if the first and second discharge rollers move away from each other by more than a prescribed distance, the control portion stops performing the post-processing in the post-processing portion.