Feeding unit and image forming apparatus having the same

Abstract

Disclosed herein are a printing media feeding unit and an image forming apparatus having the same. The feeding unit may include a feeding roller and a reverse roller arranged parallel to, and to opposingly face, each other. The feeding roller may be supported on a feeding shaft so as to rotate together with the feeding shaft. The reverse shaft may be supported on a reverse shaft so as to rotate together with the reverse shaft. The reverse shaft is arranged to be movable along the radial direction in compensation of the radial movement of the reverse roller with respect to the feed roller that may result from the friction between printing media and the reverse roller so as to improve the performance of the reverse roller in returning of extraneous sheets of printing media to prevent simultaneous feeding of multiple sheets of printing media.

1 . A feeding unit for feeding a printing medium along a printing medium feed path in an image forming apparatus, comprising:
 a feeding roller and a reverse roller arranged parallel to each other;   a feeding shaft supporting thereon the feeding roller, the feeding shaft being rotatable so as to rotate the feeding roller; and   a reverse shaft supporting at a first end thereof the reverse roller, the reverse shaft being rotatable so as to rotate the reverse roller,   wherein a second end opposite the first end of the reverse shaft being movably supported such that the second end of the reverse shaft is moveable along a radial direction substantially perpendicular to an axial direction about which the reverse shaft rotates.   
     
     
         2 . The feeding unit according to  claim 1 , further comprising:
 a frame member having an elongated opening, into which the second end of the reverse shaft is received, and along which the second end of the reverse shaft moves in the radial direction.   
     
     
         3 . The feeding unit according to  claim 1 , further comprising:
 a reverse driving gear arranged to receive a rotary force from a rotational force source;   a reverse driven gear installed adjacent the second end of the reverse shaft; and   a reverse belt rotatably supported on the reverse driving gear and the reverse driven gear.   
     
     
         4 . The feeding unit according to  claim 3 , further comprising an idle roller supporting the reverse belt and to thereby maintain a tension in the reverse belt. 
     
     
         5 . An image forming apparatus, comprising:
 a feeding unit configured to feed paper a printing medium along a printing medium feed path within the image forming apparatus, the feeding unit comprising:
 a feeding roller and a reverse roller arranged parallel to each other; 
 a feeding shaft supporting thereon the feeding roller, the feeding shaft being rotatable so as to rotate the feeding roller; and 
 a reverse shaft supporting at a first end thereof the reverse roller, the reverse roller being rotatable so as to rotate the reverse roller, 
   wherein a second end opposite the first end of the reverse shaft being movably supported such that the second end of the reverse shaft is moveable along a radial direction substantially perpendicular to an axial direction about which the reverse shaft rotates.   
     
     
         6 . The image forming apparatus according to  claim 5 , further comprising:
 a frame having an elongated opening, into which the second end of the reverse shaft is received, and along which the second end of the reverse shaft moves in the radial direction.   
     
     
         7 . The image forming apparatus according to  claim 5 , further comprising:
 a reverse driving gear arranged to receive a rotary force from a rotational force source;   a reverse driven gear installed adjacent the second end of the reverse shaft; and   a reverse belt rotatably supported on the reverse driving gear and the reverse driven gear.   
     
     
         8 . The image forming apparatus according to  claim 7 , further comprising an idle roller supporting the reverse belt and to thereby maintain a tension in the reverse belt. 
     
     
         9 . The image forming apparatus according to  claim 5 , further comprising:
 a pair of elastic members disposed to elastically bias the reverse shaft at locations along the reverse shaft adjacent each of two axial ends of the reverse roller.   
     
     
         10 . The image forming apparatus according to  claim 9 , further comprising:
 a pair of support members each having a support indentation into which the reverse shaft is received, each of the pair of support members being elastically supported by a respective corresponding one of the pair of elastic members.   
     
     
         11 . An apparatus for feeding a printing medium along a printing medium feed path of an image forming apparatus, comprising:
 a feeding roller supported on a feeding shaft, the feeding shaft being rotatable so as to rotate the feeding roller in a first rotational direction; and   a reverse roller extending parallel to, and opposingly facing, the feeding roller, the reverse roller being supported at a first axial end of a reverse shaft in such a manner to be rotatable about a rotational axis common to the reverse roller and the reverse shaft in a second rotational direction opposite the first rotational direction,   wherein a second end opposite the first end of the reverse shaft being movably supported such that the second end of the reverse shaft is moveable in a radially outward direction substantially perpendicular to the rotational axis and away from the feeding shaft.   
     
     
         12 . The apparatus of  claim 11 , wherein the reverse shaft is moveable between at least a first position and a second position, the reverse shaft being substantially parallel to the feeding shaft in each of the first and second positions. 
     
     
         13 . The apparatus of  claim 11 , further comprising:
 a frame having an elongated opening, into which the second end of the reverse shaft is received, and along which the second end of the reverse shaft moves in the radially outward direction.   
     
     
         14 . The apparatus of  claim 11 , further comprising:
 a driving gear arranged to receive a rotary force;   a driven gear coupled to the reverse shaft adjacent the second end of the reverse shaft so as to be rotatable with the reverse shaft; and   a belt rotatably supported on both the driving gear and the driven gear and configured to thereby convey the rotary force from the driving gear to the driven gear.   
     
     
         15 . The apparatus of  claim 14 , further comprising an idle roller supporting the belt and to thereby maintain a tension in the belt. 
     
     
         16 . The apparatus of  claim 11 , further comprising:
 an elastic members elastically biasing the reverse shaft toward the feeding roller.   
     
     
         17 . The apparatus of  claim 16 , wherein the elastic member comprises a first elastic member arranged at a first location along the reverse shaft adjacent a first axial end of the reverse roller and a second elastic member arranged at a second location along the reverse shaft adjacent a second axial end opposite the first axial end of the reverse roller. 
     
     
         18 . The apparatus of  claim 16 , further comprising:
 a support member that includes a support surface having a shape corresponding to the reverse shaft so as to support thereon the reverse shaft, the support member elastically supporting the support member.