Heat roller for fixing apparatus

Abstract

A heat roller for a fixing apparatus includes a conductive cylindrical roller body, and a resistance heater installed in the roller body. Caps at each end of the heat roller have electrodes for supplying a current to the resistance heater. A fastening means confines at least one cap to prevent the cap from being axially separated from the roller body and to substantially prevent the cap from being idled in the roller body.

1 . A heat roller for a fixing apparatus, comprising: 
 a conductive cylindrical roller body;    a resistance heater installed in the roller body;    a cap connected to one end of the roller body and respectively having an electrode for supplying a current to the resistance heater; and    fastening means for confining the cap to prevent the cap from axially being separated from the roller body and to substantially prevent the cap from being idled at the roller body.    
   
   
       2 . The heat roller for a fixing apparatus according to  claim 1 , wherein the fastening means includes 
 a fastening part projecting from the cap and having a fastening groove on the outer surface of the fastening part; and    a spring key disposed in the fastening groove and having a plurality of protrusions extending outwardly from an outer edge thereof.    
   
   
       3 . The heat roller for a fixing apparatus according to  claim 1 , wherein 
 the fastening means confines a gear cap.    
   
   
       4 . The heat roller for a fixing apparatus according to  claim 1 , wherein 
 the fastening means confines an end cap.    
   
   
       5 . The heat roller for a fixing apparatus according to  claim 2 , wherein 
 the fastening groove is an annular groove.    
   
   
       6 . The heat roller for a fixing apparatus according to  claim 2 , wherein 
 the fastening groove has a substantially polygonal shape.    
   
   
       7 . The heat roller for a fixing apparatus according to  claim 2 , wherein 
 the spring key is formed as a semi-circular resilient key.    
   
   
       8 . The heat roller for a fixing apparatus according to  claim 2 , wherein 
 the spring key has an inner surface having a plurality of planes.    
   
   
       9 . The heat roller for a fixing apparatus according to  claim 2 , wherein 
 the spring key is formed as two keys installed opposite to each other in the cap.    
   
   
       10 . The heat roller for a fixing apparatus according to  claim 1 , wherein 
 the cap has an inner cap installed therein.    
   
   
       11 . The heat roller for a fixing apparatus according to  claim 1 , wherein 
 a bearing is disposed on an outer surface of the roller body.    
   
   
       12 . The heat roller for a fixing apparatus according to  claim 10 , wherein 
 the cap and the inner cap are fastened to each other by a fastening member.    
   
   
       13 . The heat roller for a fixing apparatus according to  claim 2 , wherein 
 the plurality of protrusions have a substantially triangular shape.    
   
   
       14 . The heat roller for a fixing apparatus according to  claim 12 , wherein 
 an insulating member is disposed between the electrode and the fastening member.    
   
   
       15 . A heat roller for a fixing apparatus, comprising: 
 a conductive cylindrical roller body;    a resistance heater installed in the roller body;    a first cap connected to a first end of the roller body;    a second cap connected to a second end of the roller body;    first and second electrodes disposed at first and second caps, respectively, for supplying a current to the resistance heater; and    first and second fastening means for confining the first and second caps to prevent the fist and second caps from axially being separated from the roller body and to substantially prevent the first and second caps from being idled at the roller body.    
   
   
       16 . The heat roller for a fixing apparatus according to  claim 15 , wherein each of the first and second fastening means includes 
 a fastening part projecting from the cap and having a fastening groove on the outer surface of the fastening part; and    a spring key disposed in the fastening groove and having a plurality of protrusions extending outwardly from an outer edge thereof.    
   
   
       17 . The heat roller for a fixing apparatus according to  claim 16 , wherein 
 the plurality of protrusions have a substantially triangular shape.    
   
   
       18 . The heat roller for a fixing apparatus according to  claim 16 , wherein 
 the spring key is formed as a semi-circular resilient key.    
   
   
       19 . The heat roller for a fixing apparatus according to  claim 16 , wherein 
 the spring key is formed as two keys installed opposite to each other in the cap.    
   
   
       20 . The heat roller for a fixing apparatus according to  claim 15 , wherein 
 each of the first and second caps has an inner cap secured thereto by a fastening member.