Document feeding device and image forming device including the same

Abstract

A document feeding device includes a document conveyance path for conveying a document to a first document reading position and a second document reading position for reading an image. Further, the document conveyance path includes a curved conveyance path. The document feeding device includes a document feeding roller that feeds the document to the curved conveyance path and a large-diameter conveying roller disposed on an inner side of the curved conveyance path and having a diameter larger than a diameter of the document feeding roller. A document conveyance speed of the large-diameter conveying roller is higher than a document conveyance speed of the document feeding roller.

What is claimed is: 
     
         1 . A document feeding device comprising:
 a document conveyance path that conveys a document to a document reading position where an image is read, the document conveyance path including a curved conveyance path;   a sheet feeding roller that feeds the document to the curved conveyance path; and   a large-diameter conveying roller disposed on an inner side of the curved conveyance path, the large-diameter conveying roller having a diameter larger than a diameter of the sheet feeding roller, wherein   a document conveyance speed of the large-diameter conveying roller is higher than a document conveyance speed of the sheet feeding roller.   
     
     
         2 . The document feeding device according to  claim 1 , further comprising:
 a single driven roller that is in pressure contact with the large-diameter conveying roller and is driven to rotate, wherein   the document reading position is disposed downstream of the large-diameter conveying roller, and   the driven roller is disposed between the sheet feeding roller disposed upstream of the large-diameter conveying roller and the document reading position in the document conveyance path, the driven roller being disposed closer to the document reading position than to the sheet feeding roller.   
     
     
         3 . The document feeding device according to  claim 1 , further comprising:
 a sheet discharge roller disposed downstream of the large-diameter conveying roller, the sheet discharge roller discharging the document read at the document reading position to an outside, wherein   the sheet feeding roller, the large-diameter conveying roller, and the sheet discharge roller are rotationally driven by a same motor.   
     
     
         4 . The document feeding device according to  claim 3 , wherein
 each of the sheet feeding roller, the large-diameter conveying roller, and the sheet discharge roller is coupled to the motor via a transmission mechanism including a gear.   
     
     
         5 . The document feeding device according to  claim 2 , wherein
 in the document conveyance path, no conveying roller other than the large-diameter conveying roller is disposed between the sheet feeding roller and the driven roller.   
     
     
         6 . The document feeding device according to  claim 2 , wherein
 the driven roller is disposed below a horizontal plane including a rotation axis of the large-diameter conveying roller.   
     
     
         7 . The document feeding device according to  claim 2 , further comprising:
 a sheet discharge roller disposed downstream of the large-diameter conveying roller, the sheet discharge roller discharging the document read at the document reading position to an outside, wherein   the document reading position includes a first document reading position and a second document reading position, the first document reading position being a position where one surface of the document is read, the second document reading position being a position where the other surface of the document is read, the second document reading position being located downstream of the first document reading position in the document conveyance path, and   the second document reading position is closer to the sheet discharge roller than to the first document reading position.   
     
     
         8 . The document feeding device according to  claim 3 , wherein
 during a document feeding operation, the motor does not stop except when an error occurs.   
     
     
         9 . The document feeding device according to  claim 2 , further comprising:
 a sheet discharge roller disposed downstream of the large-diameter conveying roller, the sheet discharge roller discharging the document read at the document reading position to an outside, wherein   a roller that conveys the document is not provided between the driven roller and the sheet discharge roller.   
     
     
         10 . An image forming device comprising:
 the document feeding device according to  claim 1 .