Paper supply device of image forming apparatus and method

Abstract

A paper supply device and method for an image forming apparatus. The paper supply device comprises a driving unit, a first idle gear rotated by the driving unit, a first idle gear rotational shaft which is installed to pass through the first idle gear and rotates with the first idle gear, a paper conveying unit which is installed to be rotated by the first idle gear and conveying paper inward along the paper conveying path, and a multiple-feed preventing unit which is installed to be rotated by the first idle gear and preventing multiple-feed of the paper.

1 . A paper supply device of an image forming apparatus, comprising: 
 a driving motor;    a driving gear coupled to the driving motor for rotating at a predetermined speed;    a paper conveying unit for rotating by the driving gear, and conveying paper inward along a paper conveying path; and    a multiple-feed preventing unit for rotating by the driving gear, and preventing multiple-feeding of the paper.    
   
   
       2 . The paper supply device according to  claim 1 , wherein the driving gear is connected to a first idle gear rotated by the driving gear, and the paper conveying unit and the multiple-feed preventing unit are rotated by the first idle gear.  
   
   
       3 . The paper supply device according to  claim 2 , wherein the paper conveying unit includes a forward gear which is installed to engage with the first idle gear, a forward gear rotational shaft which is installed to pass through the forward gear and rotates with the forward gear, and a forward roller which is installed on the forward gear rotational shaft and rotates with the forward gear rotational shaft to convey the paper.  
   
   
       4 . The paper supply device according to  claim 3 , wherein the multiple-feed preventing unit includes a retard gear which is installed to engage with the first idle gear, a retard gear rotational shaft which is installed to pass through the retard gear and rotates with the retard gear, a torque limiter which is installed on the retard gear rotational shaft and rotates with the retard gear rotational shaft and performs a forward or reverse rotation according to paper feed friction force of the paper, and a retard roller which is connected to the torque limiter and rotates with the torque limiter and prevents the multiple-feeding of paper.  
   
   
       5 . The paper supply device according to  claim 4 , wherein the first idle gear is a multi-stage gear and includes a first-stage idle gear provided for engagement with the forward gear and a second-stage idle gear provided for engagement with the retard gear.  
   
   
       6 . The paper supply device according to  claim 5 , wherein the second-stage idle gear has a number of gear teeth smaller than that of the first-stage idle gear so that the retard gear has a rotational speed slower than that of the forward gear.  
   
   
       7 . The paper supply device according to  claim 4 , wherein: 
 the first idle gear comprises a first idle gear rotational shaft which allows the first idle gear to be rotated and rotates with the first idle gear; and    the first idle gear rotational shaft is provided with a shaft distance maintaining unit for maintaining at least one of a shaft distance between the first idle gear rotational shaft and the retard gear rotational shaft and a shaft distance between the first idle gear rotational shaft and the forward gear rotational shaft within a predetermined range.    
   
   
       8 . The paper supply device according to  claim 7 , wherein the shaft distance maintaining unit includes at least one coupling plate having two coupling holes spaced apart from each other by a predetermined distance, the two coupling holes being inserted by the first idle gear rotational shaft and a shaft shifting up and down while maintaining a predetermined distance from the first idle gear rotational shaft, respectively.  
   
   
       9 . The paper supply device according to  claim 8 , wherein the coupling plate is further provided with a pressing means for shifting and pressing one of the retard and forward rollers toward the other so that the retard and forward rollers are brought into contact with each other at a predetermined pressure.  
   
   
       10 . The paper supply device according to  claim 9 , wherein the pressing means includes an extension spring installed to pull one end of the coupling plate toward the shifted roller, the one end of the coupling plate being more adjacent to the first idle gear rotational shaft.  
   
   
       11 . The paper supply device according to  claim 7 , wherein the first idle gear rotational shaft is further provided with a plurality of feed rollers which are installed to rotate with the first idle gear rotational shaft and conveys the paper inward along the paper conveying path.  
   
   
       12 . The paper supply device according to  claim 2 , further comprising a second idle gear between the driving gear and the first idle gear, the second idle gear being engaged with both the driving gear and the first idle gear so as to transmit a rotational force of the driving gear to the first idle gear.  
   
   
       13 . The paper supply device according to  claim 1 , wherein the paper conveying unit is installed on any one of upper and lower sides of a paper conveying path.  
   
   
       14 . The paper supply device according to  claim 1 , wherein the multiple-feed preventing unit is installed on the other side of the paper conveying path which corresponds to the paper conveying unit.  
   
   
       15 . A method for supplying paper for an image forming apparatus, comprising: 
 providing a driving motor;    coupling a driving gear to the driving motor for rotating at a predetermined speed;    rotating a paper conveying unit via the driving gear, and conveying paper inward along a paper conveying path; and    rotating a multiple-feed preventing unit via the driving gear, and preventing multiple-feeding of the paper.    
   
   
       16 . The method according to  claim 15 , further comprising: 
 connecting the driving gear to a first idle gear rotated by the driving gear; and    rotating the paper conveying unit and the multiple-feed preventing unit via the first idle gear.    
   
   
       17 . The method according to  claim 16 , wherein the paper conveying unit comprises a forward gear.  
   
   
       18 . The method according to  claim 17 , further comprising: 
 engaging the forward gear with the first idle gear.    
   
   
       19 . The method according to  claim 18 , further comprising: 
 providing a forward gear rotational shaft.    
   
   
       20 . The method according to  claim 19 , wherein the forward gear rotational shaft passes through the forward gear.  
   
   
       21 . The method according to  claim 20 , further comprising: 
 rotating the forward gear rotational shaft with the forward gear.    
   
   
       22 . The method according to  claim 19 , wherein the paper conveying unit comprises a forward roller which is installed on the forward gear rotational shaft.  
   
   
       23 . The method according to  claim 22 , further comprising: 
 rotating the forward roller via the forward gear rotational shaft in order to convey the paper.