Paper controller for image forming apparatus

Abstract

A paper controller of an image forming apparatus includes a machine base having a main passage and a bypass therein. Three conveying rollers are pivoted on the machine to send papers going through the main passage and the bypass respectively. One conveying roller adjacent to the paper outlet has a driving portion and a driving-free portion, which is a flat face on the circumference, that the driving portion touches a driven roller to make it rotating and the driving-free portion will not touch the driven roller when the conveying roller is rotating that a gap is formed between the driving-free portion and the driven roller to prevent the paper from jamming at the paper outlet.

What is claimed is: 
     
         1 . A paper controller of an image forming apparatus, comprising:
 a machine base having a paper passage therein, and the paper passage including a main passage and a bypass, wherein opposite ends of the main passage are connected to a paper inlet and a paper outlet of the machine base respectively and opposite ends of the bypass are connected to the main passage and one of the end of the bypass is close to the paper outlet;   a first conveying roller pivoted on the machine base and having a portion received in the main passage;   a driven roller pivoted on the machine and having a portion received in the main passage, wherein the driven roller is closer to the paper outlet than the end of the bypass; and   a second conveying roller pivoted on the machine base and having a portion received in the main passage and association with the driven roller, wherein the second conveying roller has a driving-free portion and a driving portion, and a distance between the driving portion and a center of the second conveying roller is greater than a distance between the driving-free portion and the center of the second conveying roller that when the second conveying roller rotates, the driving portion touches the driven roller and there is a gap between the driving-free portion and driven roller.   
     
     
         2 . The paper controller as defined in  claim 1 , further comprising a third conveying roller pivoted on the machine base and having portions received in the main passage and in the bypass respectively, and a length of the driving portion of the second conveying roller is greater than a distance in the bypass between the second conveying roller and the third conveying roller. 
     
     
         3 . The paper controller as defined in  claim 1 , further comprising paper feeder provided on the machine base which includes a pre-feeding roller to move papers at the paper inlet toward the main passage in sequence and a feeding roller behind the pre-feeding roller to move the papers into the main passage in sequence. 
     
     
         4 . The paper controller as defined in  claim 1 , further comprising a controlling device to control the first and second conveying rollers to rotating in a predetermined direction and stop them and a roller sensor to sense a position of the driving-free portion of the second conveying roller. 
     
     
         5 . The paper controller as defined in  claim 1 , further comprising a controlling device to control the first and second conveying rollers to rotating in a predetermined direction and stop them, and a paper location sensor to sense a location of the paper in the passage. 
     
     
         6 . The paper controller as defined in  claim 1 , further comprising a controlling device to control the first and second conveying rollers to rotating in a predetermined direction and stop them, and a paper location sensor to sense the paper at the paper inlet. 
     
     
         7 . The paper controller as defined in  claim 4 , wherein the roller sensor includes a disk with a gap provided on an axle of the second conveying roller, and a light emitter and a light receiver at opposite sides of the disk. 
     
     
         8 . The paper controller as defined in  claim 1 , wherein the driving-free portion of the second conveying roller has a flat face. 
     
     
         9 . The paper controller as defined in  claim 1 , wherein the driving-free portion of the second conveying roller has a convex face. 
     
     
         10 . The paper controller as defined in  claim 1 , wherein the driving-free portion of the second conveying roller has a concave face.