Paper feeding apparatus for image forming apparatus

Abstract

A paper feeding apparatus for an image forming apparatus efficiently aligns the leading edge of a paper as being fed into the image forming apparatus regardless of the thickness of the paper. The paper feeding apparatus includes: first and second feeding roller assemblies rotatably installed on a paper feeding path and at least one tension idle wheel installed in anyone of the first and second feeding roller assemblies. The tension idle wheel is resiliently and elastically deformable in the radial direction thereof when the first and second feeding roller assemblies come into close contact with each other. A leading-edge alignment member is installed downstream of the first and second feeding roller assemblies to align the leading edge of a paper as being fed with respect to the apparatus.

1 . A paper feeding apparatus for an image forming apparatus, comprising: 
 first and second feeding roller assemblies rotatably mounted in a paper feeding path;    at least one tension idle wheel mounted on either the first and second feeding roller assemblies, the tension idle wheel being resiliently deformable in a radial direction thereof when the first and second feeding roller assemblies come into close contact with each other; and    a leading-edge alignment member positioned downstream of the first and second feeding roller assemblies to align the leading edge of a paper as being fed through the feeding path.    
   
   
       2 . A paper feeding apparatus as claimed in  claim 1 , wherein the tension idle wheel slip-feeds the paper when the first and second feeding roller assemblies are spaced apart from each other.  
   
   
       3 . A paper feeding apparatus as claimed in  claim 1 , further comprising: 
 a sensing unit having a plurality of sensors for sensing alignment of a leading edge of the paper with respect to the apparatus; and    a driving unit for rotationally driving the leading-edge alignment member to open the paper feeding path and concurrently causing the first and second feeding roller assemblies to come into close contact with each other when the sensing unit senses that the leading edge of the paper is in a predetermined alignment with respect to the apparatus.    
   
   
       4 . A paper feeding apparatus as claimed in  claim 3 , wherein the second feeding roller assembly comprises: 
 a plurality of rollers; and    a flexible rotary shaft for rotatably supporting the rollers, wherein the rotary shaft can be elastically deformed by an external force.    
   
   
       5 . A paper feeding apparatus as claimed in  claim 3 , wherein the tension idle wheel is installed in the second feeding roller assembly to be capable of idling.  
   
   
       6 . A paper feeding apparatus as claimed in  claim 5 , wherein the tension idle wheel comprises: 
 an outer rim which comes into close contact with the first feeding roller assembly;    an inner hub mounted on the rotary shaft of the second feeding roller assembly; and    a plurality of spokes connecting the outer rim and the inner rim, the spokes being convoluted in a predetermined angle in the radial direction.    
   
   
       7 . A paper feeding apparatus as claimed in  claim 6 , wherein the tension idle wheel includes 2 to 5 spokes convoluted in a same direction.  
   
   
       8 . A paper feeding apparatus as claimed in  claim 7 , wherein the tension idle wheel is integrally formed from a resin.  
   
   
       9 . A paper feeding apparatus as claimed in  claim 8 , wherein the outer rim has a smooth machined outer surface so that slippage occurs between a paper and the outer surface of the rim.  
   
   
       10 . A paper feeding apparatus as claimed in  claim 4 , wherein the flexible rotary shaft is formed from an optical fiber and is coupled to the sensors to function as a signal transmission path for the sensors.  
   
   
       11 . A paper feeding apparatus as claimed in  claim 4 , wherein the leading-edge alignment member comprises a blocking part positioned in the paper feeding path and an operating arm vertically depending from the blocking part, and wherein the paper feeding apparatus further comprises: 
 a hinge for pivotally supporting the leading-edge alignment member so that the blocking part selectively opens and closes the paper feeding path; and    a spring member for biasing the leading-edge alignment member to the closed position to block the paper feeding path.    
   
   
       12 . A paper feeding apparatus as claimed in  claim 11 , wherein the spring member comprises: 
 a plurality of spring holders supported by the rotary shaft of the second feeding roller assembly; and    a plurality of springs positioned between the respective holders and respective operating arms of the leading-edge alignment member.    
   
   
       13 . A paper feeding apparatus as claimed in  claim 12 , wherein the leading edge alignment member includes an operating arm, and where the driving unit comprises: 
 a cam member for selectively compressing an end of the operating arm, so that the leading-edge alignment member rotates in the direction to open the paper feeding path; and    a motor for rotating the cam member, the motor being driven according to a signal from the sensing unit.    
   
   
       14 . A paper feeding apparatus as claimed in  claim 13 , wherein the resilience and flexibility of the flexible rotary shaft is weaker than a force exerted by the compression coil springs, so that when the leading-edge alignment member rotates, the rotary shaft is resiliently deformed, whereby the first and second feeding roller assemblies come into close contact with each other.  
   
   
       15 . An image forming apparatus comprising: 
 first and second feeding roller assemblies rotatably mounted in a paper feeding path of the apparatus;    at least one tension idle wheel mounted on one of the first and second feeding roller assemblies, the tension idle wheel coming into close contact and rotating with the corresponding feeding roller assembly to slip-feed a paper through the paper feeding path when the first and second feeding roller assemblies are spaced apart from each other, and where the tension idle wheel is resiliently deformable in the radial direction thereof when the first and second feeding roller assemblies come into close contact with each other;    a leading edge alignment member for the paper positioned to selectively open and close the paper feeding path downstream of the first and second feeding roller assemblies, the leading-edge alignment member aligning a leading edge of the paper being slip-fed by the tension idle wheel when the leading-edge alignment member is in a closed position blocking the paper feeding path;    a sensing unit having a plurality of sensors for sensing alignment of the leading edge of the paper with respect to the apparatus; and    a driving unit for rotationally driving the leading-edge alignment member to open the paper feeding path when the sensing unit senses a predetermined alignment of the paper and concurrently causing the first and second feeding roller assemblies to come into close contact with each other to feed the paper through the paper feeding path of the apparatus.    
   
   
       16 . The image forming apparatus of  claim 15 , wherein 
 the first feeding roller assembly includes a first roller, the second feeding roller assembly includes a second roller, and the first roller assembly is movable from a first position where the tension idle wheel contacts the second roller and the first roller is spaced from the second roller, and a second position where the first roller contacts the second roller to feed the paper through the paper feeding path.    
   
   
       17 . The image forming apparatus of  claim 16 , wherein the at least one tension wheel and the first roller are rotatably mounted on a flexible shaft.  
   
   
       18 . The image forming apparatus of  claim 17 , wherein the at least one tension wheel has a diameter greater than a diameter of the first roller.  
   
   
       19 . The image forming apparatus of  claim 16 , wherein the leading-edge alignment member includes a movable gate member to close and block the paper feeding member, 
 and wherein the first and second feed roller assemblies feed the paper to contact the gate member to align the paper with an edge of the gate member.    
   
   
       20 . A method of aligning a paper in an image forming apparatus, the method comprising: 
 feeding a paper through a paper feed path of the apparatus into contact with a movable gate of a leading edge alignment member to align a leading edge of the paper with the gate,    sensing alignment of the leading edge of the paper with the gate, and    opening the gate in response to the sensed alignment and feeding the paper past the gate and through the paper feed path.    
   
   
       21 . The method of  claim 20 , wherein 
 the apparatus includes a first feed roller having a first roller and a tension idle wheel, and a second feed roller having a second roller, the tension idle wheel having a diameter greater than a diameter of the first roller and being resiliently deformable, the method comprising:    contacting the idle wheel with the second roller in a first position to feed the paper through the paper feed path into contact with the movable gate, and    simultaneously opening the gate and moving the first feed roller to a second position in response to the first feed roller to a second position in response to the sensed alignment of the paper, wherein the first feed roller contacts the second roller an the idle wheel is deformed when the first feed roller is in the second position.