Method and apparatus for image forming capable of effectively supporting a recording medium

Abstract

A sheet feeding unit includes a first supporting mechanism configured to support a first area of a recording medium in a range from a leading edge of the recording medium 5 to a first portion extending to an opposite direction to a sheet feeding direction of the recording medium, a second supporting mechanism configured to support a second area of the recording medium in a range from an upstream portion of the first area of the recording medium to a second portion toward a trailing edge of the recording medium, and a third supporting mechanism configured to support a third area of the recording medium in a range from an upstream portion of the second area of the recording medium to a third position after the second portion and toward the trailing edge of the recording medium.

1 . A sheet feeding unit, comprising: 
 a first supporting mechanism configured to support a recording medium on thereon;    a second supporting mechanism configured to support the recording medium, and which is disposed at an upper portion of the first supporting mechanism; and    a third supporting mechanism configured to support the recording medium, and which is disposed at an upper portion of the second supporting mechanism.    
   
   
       2 . The sheet feeding unit according to  claim 1 , wherein: 
 the first supporting mechanism is configured to support a first area of the recording medium in a range from a leading edge of the recording medium to a first portion extending to an opposite direction to a sheet feeding direction of the recording medium;    the second supporting mechanism is configured to support a second area of the recording medium in a range from an upstream of the first area of the recording medium to a second portion toward a trailing edge of the recording medium and be positioned an upper portion of the first area of the recording medium; and    the third supporting mechanism is configured to support a third area of the recording medium in a range from an upstream of the second area of the recording medium to a third position after the second portion and toward the trailing edge of the recording medium and be positioned at an upper portion of the second area of the recording medium.    
   
   
       3 . The sheet feeding unit according to  claim 2 , wherein: 
 the first supporting mechanism comprises: 
 a sheet feeding tray configured to hold the recording medium; and  
 a pair of side members movably mounted on the sheet feeding tray so that the pair of side members are movable in a direction perpendicular to the sheet feeding direction,  
   the second and third supporting mechanisms comprise a pair of guide members, each of which is detachably attached to a corresponding one of the pair of side members, the pair of guide members comprising: 
 a first pair of guide portions, each of which is integrally attached to a corresponding one of the pair of guide members, and is included in the second supporting mechanism; and  
 a second pair of guide portions, each of which integrally attached to a corresponding one of the pair of guide members, and is included in the third supporting mechanism.  
   
   
   
       4 . The sheet feeding unit according to  claim 3 , wherein: 
 the pair of side members, each of which comprises: 
 a lower plate configured to support end portions in a width direction of the first area of the recording medium;  
 a side plate integrally mounted substantially vertical with respect to the lower plate, and configured to guide a corresponding one of side ends in a width direction of the recording medium; and  
 an upper plate integrally mounted to the side plate and disposed at an upper portion of the lower plate, and configured to detachably be engaged with a corresponding one of the pair of guide members.  
   
   
   
       5 . The sheet feeding unit according to  claim 1 , wherein 
 the sheet feeding unit is included in an image forming apparatus.    
   
   
       6 . A sheet feeding unit, comprising: 
 first means for supporting a first area of a recording medium in a range from a leading edge of the recording medium to a first portion extending to an opposite direction to a sheet feeding direction of the recording medium;    second means for supporting a second area of the recording medium in a range from an upstream portion of the first area of the recording medium to a second portion toward a trailing edge of the recording medium; and    third means for supporting a third area of the recording medium in a range from an upstream portion of the second area of the recording medium to a third position after the second portion and toward the trailing edge of the recording medium.    
   
   
       7 . The sheet feeding unit according to  claim 6 , wherein: 
 the first means for supporting comprises: 
 means for holding a lower surface of the recording medium; and  
 means for leading the recording medium with the means for holding,  
   wherein said second and third means for supporting comprise means for guiding the recording medium including: 
 a first pair of guide portions integrally attached to the means for leading and included in the second means for supporting; and  
 a second pair of guide portions integrally attached to the means for leading and included in the third means for supporting.  
   
   
   
       8 . The sheet feeding unit according to  claim 6 , wherein: 
 the first, second, and means for supporting are included in an image forming apparatus.    
   
   
       9 . A method of feeding of supporting a recording medium, comprising: 
 supporting a first area of a recording medium in a range from a leading edge of the recording medium to a first portion extending to an opposite direction to a sheet feeding direction of the recording medium;    supporting a second area of the recording medium in a range from an upstream portion of the first area of the recording medium to a second portion toward a trailing edge of the recording medium; and    supporting a third area of the recording medium in a range from an upstream portion of the second area of the recording medium to a third position after the second portion and toward the trailing edge of the recording medium.    
   
   
       10 . The method according to  claim 9 , wherein: 
 the supporting of the first area comprises: 
 holding a lower surface of the recording medium; and  
 leading the recording medium while holding the recording medium, and  
   the supporting of the second and third areas comprises guiding the recording medium with first and second pairs of guide portions.