Apparatus for varying pressure roll nip force

Abstract

An apparatus for varying nip pressure in a media feedpath including a feed roller and a pressure roller defining a feed nip there between includes a rotatable cam having a preselected eccentric path when rotated, a first pivotable linkage pivotally engaging the rotatable cam, a second pivotable linkage, a biasing member operably interconnecting the first and second pivotal linkages for providing a biasing force on the pressure roller. The pressure roller is rotatably connected to the second linkage opposite the biasing member, wherein rotation of the cam varies the biasing force provided by the biasing member on the pressure roller.

1 . An apparatus for varying nip pressure in a media feedpath including a feed roller and a pressure roller defining a feed nip therebetween, comprising: 
 a rotatable cam having a preselected eccentric path when rotated;    a first pivotable linkage pivotally engaging said rotatable cam;    a second pivotable linkage;    a biasing member operably interconnecting said first and second pivotal linkages for providing a biasing force on said pressure roller; and,    said pressure roller rotatably connected to said second linkage opposite said biasing member;    wherein rotation of said cam varies the biasing force provided by said biasing member on said pressure roller.    
   
   
       2 . The apparatus of  claim 1  wherein said cam has an eccentric shape.  
   
   
       3 . The apparatus of  claim 2  further comprising a rotatable shaft operably connected to said cam.  
   
   
       4 . The apparatus of  claim 1  wherein said first linkage pivots about a first linkage pivot point as said cam rotates.  
   
   
       5 . The apparatus of  claim 1  wherein rotation of said cam the loads and unloads said biasing member connected to said first linkage and said second linkage as said cam is rotated.  
   
   
       6 . The apparatus of  claim 5  wherein said pressure roller exerts greater force on said feed roll as said biasing member is loaded and exerts lesser force on said feed roll as said biasing member is unloaded.  
   
   
       7 . The apparatus of  claim 1 , wherein said pressure roller comprises a plurality of pressure rollers.  
   
   
       8 . A variable pressure roll linkage for media feedpath, comprising: 
 an elastic member;    a first linkage;    a feed drive roller and a pressure roller defining a nip therebetween;    a second linkage with said pressure roller operably connected to said second linkage with said first linkage connected to said second linkage by said elastic member; and,    a cam moveable about a preselected profile engaging said first linkage wherein movement of said cam loads and unloads said elastic member and causes translation of said pressure roller at said nip.    
   
   
       9 . The variable pressure roll linkage of  claim 8 , wherein said pressure roller is translatable toward and away from said feed drive roller.  
   
   
       10 . The variable pressure roll linkage of  claim 8  wherein rotation of said cam pivots said first linkage.  
   
   
       11 . The variable pressure roll linkage of  claim 8 , said elastic member further comprising a spring.  
   
   
       12 . The variable pressure roll linkage of  claim 8  wherein application of tension to said elastic member increases force of said pressure roll toward said drive roll.  
   
   
       13 . The variable pressure roll linkage of  claim 12 , said application of tension is caused by movement of said cam.  
   
   
       14 . The variable pressure roll linkage of  claim 8 , said pressure roll further comprising a plurality of pressure rolls mounted on a pressure roll shaft and said drive roller comprising at least one drive roller mounted on a drive roll shaft.  
   
   
       15 . A pressure roll linkage for applying variable pressure to a pressure roll, comprising: 
 a pivotable follower plate;    said follower plate engaged by a mover to cause pivotal movement of said follower plate;    a pressure roller housing adjacent said follower plate, said pressure roller housing having at least one pressure roller; and,    a biasing member having a first portion and a second portion, said first portion connected to said follower plate and said second portion connected to said pressure roller housing;    wherein actuation of said mover varies pressure applied by said pressure roller.    
   
   
       16 . The pressure roll linkage of  claim 15  wherein said follower plate pivots in a first direction and said pressure roller housing pivots in a second opposite direction when loading said biasing member.  
   
   
       17 . The pressure roll linkage of  claim 15 , said pressure roller moving toward and away from a drive roll when said mover is actuated and deactuated.  
   
   
       18 . The pressure roll linkage of  claim 15 , said biasing member being a spring which is tensioned and untensioned as said mover is actuated and deactuated.  
   
   
       19 . The pressure roll linkage of  claim 15 , said linkage positioned in a printer feedpath.  
   
   
       20 . The pressure roll linkage of  claim 15 , said linkage positioned in a scanner auto-document feeder feedpath.  
   
   
       21 . The pressure roll linkage of  claim 15  said mover being an eccentric cam.  
   
   
       22 . A variable force pressure roll linkage, comprising: 
 a media feedpath;    a drive roller located along said media feedpath;    a biasable idler roller rotatably disposed opposite and biased toward said drive roller and forming a nip therebetween for feeding media; and,    a variable force means which decreases biasing force on said idler roller during media exit from said nip.    
   
   
       23 . A variable force pressure roll linkage, comprising: 
 a media feedpath;    a drive roller located along said media feedpath;    an idler roller disposed opposite and biased toward said drive roller;    a first linkage and a second linkage connected by a biasing member;    said idler roller rotatably connected to said second linkage; and,    motion means operably coupled to said first linkage for varying force on said idler roller during media feed.