Medium discharging mechanism and image forming apparatus that employs the medium discharging mechanism

Abstract

A medium discharging mechanism includes a first roller, a second roller, and a resiliently deformable member. The second roller is in pressure contact with the first roller to form a nip between the first roller and the second roller. The resiliently deformable member is formed of a resiliently deformable material and is rotatable about a rotating shaft of one of the second roller. The resilient member has a larger diameter than the second roller. The resilient member deforms at the nip such that a surface of the resilient ring is flush with the nip.

1 . A medium discharging mechanism, comprising:
 a first roller;   a second roller in contact with said first roller; and   a resiliently deformable member mounted to said second roller and including a large diameter than said second roller, said deformable member facing said first roller, wherein said resiliently deformable member includes a diameter that varies along its circumference.   
   
   
       2 . The medium discharging mechanism according to  claim 1 , wherein said first roller is formed of a resilient body and said second roller is formed of a resin material being driven by said first roller to rotate together with said first roller when said first roller rotates. 
   
   
       3 . The medium discharging mechanism according to  claim 1 , wherein said second roller includes an annular groove that is formed in a circumferential surface of said second roller and receives said resilient deformable body therein, the groove being formed at substantially a longitudinally middle portion of said second roller;
 wherein said resiliently deformable member includes an inner diameter;   wherein said the groove includes a bottom surface having a diameter larger than the inner diameter.   
   
   
       4 . The medium discharging mechanism according to  claim 3 , further comprising an urging member by which said second roller is urged against said first roller. 
   
   
       5 . The medium discharging mechanism according to  claim 1 , wherein said second roller is positioned downstream of said first roller with respect to a transport path of the medium and forms a nip between said first roller and said second roller, the nip lying in a plane at an angle with the transport path in which the medium advances toward the nip. 
   
   
       6 . The medium discharging mechanism according to  claim 1 , wherein the diameter varies at a plurality of locations along the circumference of said resiliently deformable member. 
   
   
       7 . The medium discharging mechanism according to  claim 1 , wherein said second roller includes an annular groove formed in a circumferential surface of said second roller and said resiliently deformable member is in the shape of a ring fitted in the annular groove. 
   
   
       8 . The medium discharging mechanism according to  claim 7 , wherein said resiliently deformable member deforms at a nip formed between said first roller and said second roller. 
   
   
       9 . The medium discharging mechanism according to  claim 8 , wherein said resiliently deformable member deforms such that a surface of the resiliently deformable member is flush with the nip. 
   
   
       10 . The medium discharging mechanism according to  claim 1 , wherein said resiliently deformable member is made of urethane foam. 
   
   
       11 . The medium discharging mechanism according to  claim 1 , wherein said medium discharging mechanism is incorporated in an image forming apparatus. 
   
   
       12 . The medium discharging mechanism according to  claim 1 , wherein said resiliently deformable member includes projections and recesses aligned alternately on a circumferential surface of said resiliently deformable member. 
   
   
       13 . The medium discharging mechanism according to  claim 1 , wherein said resiliently deformable member has projections and recesses on its circumferential outer surface such that the projections and recesses form a wavy surface. 
   
   
       14 . The medium discharging mechanism according to  claim 1 , wherein said resiliently deformable member is mounted outside of an area in which said first roller and said second roller are in contact with each other. 
   
   
       15 . The medium discharging mechanism according to  claim 1 , wherein said resiliently deformable member is one of at least two resiliently deformable members mounted on longitudinal end portions of said second roller. 
   
   
       16 . The medium discharging mechanism according to  claim 1 , wherein said second roller is one of a plurality of second rollers that rotate about the rotating shaft, wherein said resiliently deformable member is disposed such that said resiliently deformable member is sandwiched between adjacent second rollers. 
   
   
       17 . The medium discharging mechanism according to  claim 16 , further comprising a weight member that is freely rotatable on the rotating shaft and hangs down from the rotating shaft,
 wherein when the medium is pulled in between said first roller and said second roller, the leading end of the medium pushes the weight member out of the way so that the weight member presses a surface of the medium until a trailing end of the medium leaves the nip.