Constant lead edge paper inverter system

Abstract

A printing apparatus capable of duplex imaging that maintains the lead edge of a sheet constant, is disclosed. The printing apparatus includes a first transport path to route a sheet along a processing direction, an edge position detector to detect a lead edge of the sheet, a marking device that prints on a first side of the sheet, a second transport path to receive the sheet from the marking device, and an inverter mechanism that receives the sheet from the second transport path and inverts the sheet along a cross-processing direction that is perpendicular to the processing direction. The printing apparatus also includes a third transport path that receives the inverted sheet and routes the inverted sheet back to the first transport path. With this configuration, upon being routed back to the first transport path, the edge position detector detects the same lead edge of the sheet as previously detected and the marking device prints on a second side of the sheet.

1 . A printing apparatus, comprising: 
 a first transport path configured to route a sheet along a processing direction;    an edge position detector configured to detect a lead edge of the sheet;    a marking device configured to print on a first side of the sheet;    a second transport path configured to receive the sheet from the marking device;    an inverter mechanism configured to receive the sheet from the second transport path and invert the sheet along a cross-processing direction that is perpendicular to the processing direction; and    a third transport path configured to receive the inverted sheet and route the inverted sheet back to the first transport path,    wherein, upon being routed back to the first transport path, the edge position detector detects the same lead edge of the sheet and the marking device prints on a second side of the sheet.    
   
   
       2 . The printing apparatus of  claim 1 , wherein the inverter mechanism comprises a U-shaped inverter.  
   
   
       3 . The printing apparatus of  claim 2 , wherein the U-shaped inverter includes a plurality of rolls.  
   
   
       4 . The printing apparatus of  claim 2 , wherein the U-shaped inverter includes a vacuum transport.  
   
   
       5 . The printing apparatus of  claim 1 , wherein the first, second, and third transport paths are arranged to form a circuit path.  
   
   
       6 . The printing apparatus of  claim 1 , wherein the first, second, and third transport paths include a plurality of drive roller nips that engage the sheet and are oriented and aligned to guide the sheet along the processing direction.  
   
   
       7 . The printing apparatus of  claim 1 , wherein the inverter mechanism includes a plurality of cross-drive roller nips that engage the sheet and are oriented and aligned to guide the sheet along the cross-processing direction.  
   
   
       8 . The printing apparatus of  claim 1 , wherein the first transport path includes an input portion to initially receive the sheet and an output portion to output the sheet.  
   
   
       9 . The printing apparatus of  claim 1 , wherein the second transport path includes an intake portion to receive the sheet from the first transport path.  
   
   
       10 . The printing apparatus of  claim 1 , wherein the third transport path includes an output portion to direct the sheet back to the first transport path.  
   
   
       11 . A sheet inverter mechanism, comprising: 
 a U-shaped inverter configured to receive a sheet along a processing direction; and    a plurality of roller nips oriented and arranged to engage and drive the sheet across the U-shaped inverter to invert the sheet, the sheet being inverted along a cross-processing direction that is perpendicular to the processing direction,    wherein a lead edge of the sheet prior to being inverted remains on a same side after being inverted.    
   
   
       12 . A method of printing on opposite sides of a sheet, comprising: 
 routing the sheet across a first transport path along a processing direction;    detecting a lead edge of the sheet;    printing on one side of the sheet;    routing the sheet across a second transport path;    inverting the sheet along a cross-processing direction that is perpendicular to the processing direction;    routing the sheet across a third transport path that feeds back towards the first transport path;    detecting the same lead edge; and    printing on a second side of the sheet.    
   
   
       13 . The method of  claim 12 , wherein the inverting of the sheet includes engaging and driving the sheet across a U-shaped inverter along the cross-processing direction.  
   
   
       14 . The method of  claim 12 , wherein the first, second, and third transport paths are arranged to form a circuit path.  
   
   
       15 . The method of  claim 12 , wherein the routing of the sheet within the first, second, and third transport paths includes the use of a plurality of drive roller nips that are oriented and aligned to engage and guide the sheet along the processing direction.  
   
   
       16 . The method of  claim 12 , wherein the inverting of the sheet includes the use of a plurality of cross-drive roller nips that are oriented and aligned to engage and guide the sheet along the cross-processing direction.