Sheet discharging device and sheet post-processing apparatus therewith, and image forming system

Abstract

A protruding member is supported so as to be reciprocatable between a protrusion position and a retraction position. The protrusion position is where the protruding member protrudes from a discharge port to above a stacking tray and brings, into contact with its top surface, the leading edge of a sheet discharged by a pair of discharging rollers to guide it in the discharging direction. The retraction position is where the protruding member is retracted from above the stacking tray. A moving mechanism has a supporting holder movably holding the protruding member and makes the held protruding member move between the protrusion position and the retraction position. A sensing portion sensing whether the protruding member is in the retraction position is disposed in the supporting holder.

What is claimed is: 
     
         1 . A sheet discharging device comprising:
 a pair of discharging rollers discharging a sheet through a discharge port;   a stacking tray disposed downstream of the pair of discharging rollers with respect to a discharging direction of the sheet, the stacking tray having stacked thereon the sheet discharged by the pair of discharging rollers;   a protruding member supported so as to be reciprocatable between a protrusion position where the protruding member protrudes from the discharge port to above the stacking tray and where the protruding member brings, into contact with a top surface thereof, a leading edge of the sheet discharged by the pair of discharging rollers to guide the sheet in the discharging direction, and a retraction position where the protruding member is retracted from above the stacking tray; and   a moving mechanism having a supporting holder movably holding the protruding member, the moving mechanism making the protruding member move between the protrusion position and the retraction position,   wherein
 the sheet discharging device further comprises a sensing portion sensing whether the protruding member is in the retraction position, and 
 the sensing portion is disposed in the supporting holder. 
   
     
     
         2 . The sheet discharging device according to  claim 1 , wherein
 the sensing portion is an optical sensor including a light emitting portion and a light receiving portion disposed opposite each other and senses, when the protruding member enters or retracts from an optical path of the optical sensor, whether the protruding member is in the retraction position.   
     
     
         3 . The sheet discharging device according to  claim 2 , wherein
 the optical sensor is disposed at a downstream end part of the protruding member in a retraction direction thereof, and   the sensing portion senses, when the protruding member enters the optical path of the optical sensor, presence of the protruding member in the retraction position.   
     
     
         4 . A sheet post-processing apparatus comprising:
 the sheet discharging device according to  claim 1 ; and   a post-processing mechanism performing predetermined post-processing on the sheet and conveying the post-processed sheet to the sheet discharging device.   
     
     
         5 . An image forming system comprising:
 the sheet post-processing apparatus according to claim  4 ; and   an image forming apparatus forming an image on the sheet and conveying the sheet having the image formed thereon to the sheet post-processing apparatus.