Media registration systems and methods

Abstract

Embodiments herein measure current/voltage levels of a drive motor when media is in contact with a drive roller so as to determine the drive force imparted by the drive rollers on the media. Then, embodiments herein can reference the predetermined relationship between roller drive force and media/drive roller velocity ratios to determine a difference between the velocity of the drive roller and the velocity the media based on the drive force. Once this velocity difference is determined, embodiments herein can change the current/voltage levels being applied to the drive motor if the actual velocity of the media is different than the intended velocity of the media so as to correct the velocity of the media. Thus, when referencing the predetermined relationship, embodiments herein produce a velocity ratio correction factor. This velocity ratio correction factor can be applied continuously during any velocity profile of the drive motor, or it can be used to calculate the accumulated error in sheet position and then to apply a correction near the end of the velocity profile.

1 . A method comprising: 
 measuring current/voltage levels, comprising at least one of current and voltage levels, applied to a drive motor connected to a drive roller in a drive nip assembly adapted to move media within one of a printing and copying apparatus;    determining a difference between a velocity of said drive roller and a velocity said media based on said current/voltage levels; and    changing said current/voltage levels begin applied to said drive motor if an actual velocity of said media is different than an intended velocity of said media.    
   
   
       2 . The method of  claim 1 , further comprising determining a drive force on said drive motor based on said current/voltage levels, wherein said drive force is used in said determining of said difference between said velocity of said drive roller and said velocity of said media.  
   
   
       3 . The method according to  claim 1 , further comprising continually repeating said measuring, said determining, and said changing when said media is in said drive nip assembly.  
   
   
       4 . The method according to  claim 1 , further comprising: 
 continually repeating said measuring and said determining when said media is in said drive nip assembly; and    performing said changing as said media is exiting said drive nip assembly.    
   
   
       5 . The method according to  claim 1 , further comprising: 
 detecting an initial media skew as said media enters said drive nip assembly; and    using unequal application of at least two drive nip assemblies to correct for said initial media skew.    
   
   
       6 . A method comprising: 
 establishing a predetermined relationship between current/voltage levels and media/drive roller velocity ratios, wherein said current/voltage levels comprise at least one of current and voltage levels, applied to a drive motor connected to a drive roller in a drive nip assembly adapted to move media within one of a printing and copying apparatus, and wherein said media/drive roller velocity ratios comprise velocity relationships between said drive roller and said media when said media is in contact with said drive roller;    measuring current/voltage levels of said drive motor when said media is in contact with said drive roller;    referencing said predetermined relationship to determine a difference between a velocity of said drive roller and a velocity said media based on said current/voltage levels; and    changing said current/voltage levels begin applied to said drive motor if an actual velocity of said media is different than an intended velocity of said media.    
   
   
       7 . The method according to  claim 6 , wherein said predetermined relationship is associated with said drive nip assembly.  
   
   
       8 . The method according to  claim 6 , wherein said referencing of said predetermined relationship produces a velocity ratio correction factor.  
   
   
       9 . The method according to  claim 8 , further comprising applying said velocity ratio correction factor to all velocity profiles of said drive motor.  
   
   
       10 . The method according to  claim 6 , further comprising calibrating said current/voltage levels of said drive motor when none of said media is present in said drive nip assembly.  
   
   
       11 . An apparatus comprising: 
 a drive nip assembly adapted to move media within one of a printing and copying apparatus;    a drive motor within said drive nip assembly;    a drive roller connected to said drive motor; and    a control system connected to said drive motor,    wherein said control system is adapted to:    measure current/voltage levels, comprising at least one of current and voltage levels, applied to said drive motor;    determine a difference between a velocity of said drive roller and a velocity said media based on said current/voltage; and    change said current/voltage levels begin applied to said drive motor if an actual velocity of said media is different than an intended velocity of said media.    
   
   
       12 . The apparatus according to  claim 11 , wherein said control system is further adapted to reference a predetermined relationship between said current/voltage levels and media/drive roller velocity ratios to determine said difference between said velocity of said drive roller and said velocity of said media.  
   
   
       13 . The apparatus according to  claim 12 , wherein said control system is further adapted to produce a velocity ratio correction factor when referencing said predetermined relationship.  
   
   
       14 . The apparatus according to  claim 13 , wherein said control system is further adapted to applying said velocity ratio correction factor to all velocity profiles of said drive motor.  
   
   
       15 . The apparatus according to  claim 11 , wherein said control system is further adapted to calibrate said current/voltage levels of said drive motor when none of said media is present in said drive nip assembly.  
   
   
       16 . An apparatus comprising: 
 a drive nip assembly adapted to move media within one of a printing and copying apparatus;    a drive motor within said drive nip assembly;    a drive roller connected to said drive motor; and    a control system connected to said drive motor,    wherein a predetermined relationship exists between current/voltage levels and media/drive roller velocity ratios, wherein said current/voltage levels comprise at least one of current and voltage levels, applied to said drive motor, and wherein said media/drive roller velocity ratios comprise velocity relationships between said drive roller and said media when said media is in contact with said drive roller, and    wherein said control system is adapted to:    measure current/voltage levels of said drive motor when said media is in contact with said drive roller;    reference said predetermined relationship to determine a difference between a velocity of said drive roller and a velocity of said media based on said current/voltage; and    change said current/voltage levels begin applied to said drive motor if an actual velocity of said media is different than an intended velocity of said media.    
   
   
       17 . The apparatus according to  claim 11 , wherein said predetermined relationship is associated with said drive nip assembly.  
   
   
       18 . The apparatus according to  claim 16 , wherein said control system is further adapted to produce a velocity ratio correction factor when referencing said predetermined relationship.  
   
   
       19 . The apparatus according to  claim 18 , wherein said control system is further adapted to applying said velocity ratio correction factor to all velocity profiles of said drive motor.  
   
   
       20 . The apparatus according to  claim 16 , wherein said control system is further adapted to calibrate said current/voltage levels of said drive motor when none of said media is present in said drive nip assembly.