Media Sheet Guide Device and Method for Maintaining Proper Sheet Alignment in an Image Forming Machine

Abstract

A media sheet guide device for maintaining proper sheet alignment in an image forming machine includes a body extending between spaced apart reference edges of respective upstream and downstream media alignment mechanisms and a face on the body defining a path along which a sheet moves lengthwise from the upstream reference edge to the downstream reference edge. The face has a section extending widthwise and defining a portion of the path about which the sheet bends widthwise as the sheet moves lengthwise along the path portion. The face section has first and second segments differing in curvature for applying a differential drag widthwise across the sheet causing a rotation of the sheet sufficiently to displace a leading end of the sheet away from the downstream reference edge to thereby ensure that a leading corner of the sheet can enter into the downstream reference edge without jamming against an entry end thereof.

1 . A media sheet guide device for maintaining sheet alignment in an image forming machine, comprising:
 an upper guide having a curved face; and   a lower guide having a curved opening therein, said upper guide positioned within the curved opening, said upper and lower guides forming a curved path therebetween along which a sheet moves;   said upper guide comprising:
 a body extending between spaced apart reference edges of respective upstream and downstream media alignment mechanisms in a image forming machine; and 
 a face on said body defining said curved path along which a sheet moves lengthwise from the reference edge of the upstream media alignment mechanism to the reference edge of the downstream media alignment mechanism; 
 said face having a section extending widthwise and defining a portion of said curved path about which the sheet bends widthwise as the sheet moves lengthwise along said portion of said curved path, said section of said face having first and second segments differing in curvature for applying a differential drag widthwise across the sheet as the sheet bends widthwise and moves lengthwise along said portion of said curved path, said application of said differential drag across the sheet causing a rotation of the sheet sufficiently to displace a leading end of the sheet away from the reference edge of the downstream media alignment mechanism, thereby ensuring that a leading corner of the sheet can enter into the reference edge of the downstream media alignment mechanism without jamming against an entry end of the reference edge of the downstream media alignment mechanism. 
   
     
     
         2 . The device of  claim 1  wherein said first segment of said section of said face aligns with the sheet along a first portion thereof at a first side of a centerline of the sheet, said second segment of said section of said face aligns with the sheet along a second portion thereof at a second side of the centerline of the sheet opposite from the first side of the sheet such that the first segment is displaced farther than said second segment from the reference edge of the downstream media alignment mechanism. 
     
     
         3 . The device of  claim 2  wherein said curvature of said first segment of said section of said face has a first bend radius and said curvature of said second segment of said section of said face has a second bend radius longer than said first bend radius such that greater drag is applied on the sheet at the first portion thereof by said first segment of said face located more remote from the downstream reference edge than at the second portion thereof by said second segment of said face located more adjacent to the reference edge of the downstream media alignment mechanism. 
     
     
         4 . The device of  claim 1  wherein said curvature of said first segment of said face has a first bend radius and said curvature of said second segment has a second bend radius longer than said first radius such that greater drag is applied on the sheet farther from the reference edge of the downstream media alignment mechanism by said first segment of said face than by said second segment of said face. 
     
     
         5 . The device of  claim 4  wherein said first segment of said face is disposed at different locations widthwise along said section of said face depending upon which one of different sizes of sheets the differential drag is to be applied. 
     
     
         6 . A media sheet guide device for maintaining sheet alignment in an image forming machine, comprising:
 an upper guide having a curved face; and   a lower guide having a curved opening therein, said upper guide positioned within the curved opening, said upper and lower guides forming a curved path therebetween along which a sheet moves;   said upper guide comprising:   a body extending between spaced apart referenced edges of upstream and downstream media alignment mechanisms in said machine and having a face defining said curved path along which a sheet moves from the upstream reference edge to the downstream reference edge;   a base of said body extending between the upstream and downstream reference edges; and   a plurality of guide ribs formed on said base so as to define at least a portion of said face of said body, said guide ribs being laterally spaced apart widthwise of said base and having heights through which they protrude outwardly from said base, said guide ribs also having respective downstream end portions with curvatures extending lengthwise in the direction of the path and about which downstream end portions the sheet bends as the sheet approaches the downstream reference edge, selected ones of said downstream end portions of said guide ribs having at least one extension which protrudes outwardly from said guide rib end portions so as to modify said lengthwise extending curvatures thereof such that a differential drag is applied to the sheet that causes rotation of the sheet sufficient to displace a leading end thereof away from the downstream reference edge ensuring that a leading corner of the sheet may enter into the downstream reference edge without jamming against the downstream reference edge.   
     
     
         7 . The device of  claim 6  wherein said selected ones of said guide rib end portions having said extension aligns with the sheet along a first portion thereof at a first side of a centerline of the sheet and at least one of said guide rib end portions without said extension aligns with the sheet along a second portion thereof at a second side of the centerline of the sheet opposite from the first side of the sheet such that said selected guide rib end portions with said extension is displaced farther from the downstream reference edge than said at least one of said guide rib end portions without said extension. 
     
     
         8 . The device of  claim 7  wherein said curvature of said downstream end portions of said selected ones of said guide ribs with said extension has a first bend radius and said curvature of said guide rib end portions without said extension has a second bend radius longer than said first bend radius such that greater drag is applied on the sheet at the first portion thereof located more remote from the downstream reference edge than at the second portion thereof located more adjacent to the downstream reference edge. 
     
     
         9 . The device of  claim 6  wherein said curvature of said downstream end portions of said selected ones of said guide ribs with said extension has a first bend radius and said curvature of said guide rib end portions without said extension has a second bend radius longer than said first radius such that greater drag is applied on the sheet farther from the downstream reference edge by said guide rib end portions with said extension than by said guide rib end portions without said extension. 
     
     
         10 . The device of  claim 9  wherein said selected ones of said guide rib end portions with said extension are disposed at different locations widthwise of said base depending upon to which one of different sizes of sheets the differential drag is to be applied. 
     
     
         11 . The device of  claim 6  wherein said guide ribs are spaced apart from one another by substantially the same amount of distance. 
     
     
         12 . The device of  claim 11  wherein said heights at which said guide ribs protrude outwardly from said base are substantially the same. 
     
     
         13 . A method for maintaining proper sheet alignment in an image forming machine, comprising:
 defining a path along which a sheet moves lengthwise from an upstream reference edge of an upstream media alignment mechanism to a downstream reference edge of a downstream media alignment mechanism; and   applying a differential drag widthwise across the sheet causing a rotation of the sheet sufficiently to displace a leading end of the sheet away from the downstream reference edge to thereby ensure that a leading corner of the sheet can enter into the downstream reference edge without jamming against an entry end thereof.   
     
     
         14 . The method of  claim 13  wherein said applying the differential drag includes applying a greater drag to the sheet along a first portion of the sheet at a first side of a centerline of the sheet and a lesser drag to the sheet along a second portion of the sheet at a second side of the centerline of the sheet opposite from the first side of the sheet. 
     
     
         15 . The method of  claim 14  wherein the first portion of the sheet where the greater drag is applied is located farther from the downstream reference edge than the second portion of the sheet where the lesser drag is applied.