Roller-load changing apparatus usable with office machine

Abstract

A roller-load changing apparatus usable with an office machine, such as a facsimile and a convergence machine, includes a document detecting sensor to determine whether a document is stacked, a feed roller to feed the document, a first pinch roller movable between a first pressing position to press the document against the feed roller and a first releasing position to release a pressing force of the first pinch roller, an ejection roller disposed in a downward document feeding direction of the feed roller to eject the document, a second pinch roller movable between a second pressing position to press the document against the ejection roller and a second releasing position to release a pressing force of the second pinch roller, and a roller-load changing unit to change the pressing position of the first and the second pinch rollers when a trailing portion of the document ejects from a nip formed between the feed roller and the first pinch roller

1 . A paper feeding apparatus comprising: 
 a feed roller to feed a document;    a pinch roller to exert a force on the feed roller to cause the feed roller to feed the document; and    a force controlling unit to adjust the force exerted on the feed roller by the pinch roller as the document is fed.    
   
   
       2 . The paper feeding apparatus as claimed in  claim 1 , wherein the force controlling unit comprises: 
 a lever elastically connected to the pinch roller to adjust the force exerted on the feed roller by the pinch roller.    
   
   
       3 . The paper feeding apparatus as claimed in  claim 2 , wherein the force controlling unit further comprises: 
 a cam connected to the lever to raise and lower the lever; and    a motor to drive the cam.    
   
   
       4 . The paper feeding apparatus as claimed in  claim 1 , further comprising: 
 a document detector to detect a position of the document, wherein the force controlling unit controls the force of exerted on the feed roller by the pinch roller according to the position of the document detected by the document detector.    
   
   
       5 . A paper feeding apparatus usable with an image forming apparatus, comprising: 
 a feed roller to feed a document into the image forming apparatus;    a first pinch roller to exert a first force on the feed roller to allow the document to pass between the feed roller and the first pinch roller;    an ejection roller to discharge the document from the image forming apparatus;    a second pinch roller to exert a second force on the ejection roller to allow the document to pass between the ejection roller and the second pinch roller; and    a lever elastically connected to the first and second pinch rollers to control the first and second forces.    
   
   
       6 . The paper feeding apparatus as claimed in  claim 5 , wherein the lever comprises: 
 a first end portion elastically connected to the first pinch roller;    a second end portion elastically connected to the second pinch roller; and    a center portion about which the first and second end portions pivot, wherein when the first end portion is raised the second end portion is lowered, and when the second end portion is raised the first end portion is lowered.    
   
   
       7 . The paper feeding apparatus as claimed in  claim 6 , further comprising: 
 an operating unit to raise and lower the first and second end portions of the lever to control the first and second forces.    
   
   
       8 . The paper feeding apparatus as claimed in  claim 7 , wherein the operating unit comprises: 
 a cam disposed at the first end portion of the lever to lift the first end of the lever; and    a motor to drive the cam to lift the first end portion of the lever.    
   
   
       9 . The paper feeding apparatus as claimed in  claim 8 , wherein the operating unit further comprises: 
 an elastic member disposed at the second end portion of the lever to raise the second end portion to raise the second end portion of the lever and to lower the first end portion of the lever when the cam is not lifting the first end portion of the lever.    
   
   
       10 . The paper feeding apparatus as claimed in  claim 5 , wherein the lever causes the second force to increase when first force is decreased, and the first force to increase when the second force is decreased.  
   
   
       11 . The paper feeding apparatus as claimed in  claim 5 , wherein while the feed roller feeds the paper, the first force is gradually decreased and the second force is gradually increased.  
   
   
       12 . The paper feeding apparatus as claimed in  claim 5 , wherein the first force disappears at a time at which the feed roller finishes feeding the document.  
   
   
       13 . A paper feeding apparatus usable with an image forming apparatus, comprising: 
 a feed roller unit to feed a document into the image forming apparatus;    an ejection roller unit to eject the document out of the image forming apparatus; and    a roller-load changing unit to adjust operations of the feed roller unit and the ejection roller unit proportionally with respect to a distance at which the document advances through the image forming apparatus.    
   
   
       14 . The paper feeding apparatus as claimed in  claim 13 , wherein the feed roller unit comprises a feed roller and a first pinch roller movable between a first pressing position to press the document against the feed roller and a first releasing position to release a pressing force of the first pinch roller, and the ejection roller unit comprises an ejection roller and a second pinch roller movable between a second pressing position to press the document against the ejection roller and a second releasing position to release a pressing force of the second pinch roller.  
   
   
       15 . The paper feeding apparatus as claimed in  claim 14 , wherein the roller load changing unit comprises a load changing lever to increase the pressing force between one of the first pinch roller and the feed roller combination and the second pinch roller and the ejection roller combination, while decreasing the pressing force between the other one of the first pinch roller and the feed roller combination and the second pinch roller and the ejection roller combination.  
   
   
       16 . A method of feeding a document through an office machine comprising: 
 feeding a document into the office machine through a first set of rollers by applying a pressure therebetween;    ejecting the document out of the office machine through a second set of rollers by applying a pressure therebetween; and    controlling an adjustment of the pressure between the first set of rollers and an adjustment of the pressure between the second set of rollers based on an advancement position within the office machine.