Method and apparatus for assuring proper media feeding

Abstract

This invention relates to an apparatus for assuring media feeding, comprising: an impression drum having a media gripper; an input feed unit located substantially adjacent to the impression drum for feeding a sheet of media; and a servo motor operatively connected to the input feed unit such that a change in operating characteristics of the servo motor is detected if the sheet of media is properly retained by the gripper.

1 . An apparatus for assuring media feeding, comprising: 
 an impression drum having a media gripper;    an input feed unit located substantially adjacent to the impression drum for feeding a sheet of media; and    a servo motor operatively connected to the input feed unit such that a change in operating characteristics of the servo motor is detected if the sheet of media is properly retained by the gripper.    
   
   
       2 . The apparatus, as in  claim 1 , wherein the input feed unit is further comprised of: 
 a plurality of rollers that create a nip.    
   
   
       3 . The apparatus, as in  claim 1 , wherein the apparatus is further comprised of: 
 a servo motor controller operatively connected to the servo motor to control operating characteristics of the servo motor.    
   
   
       4 . The apparatus, as in  claim 1 , wherein the apparatus is further comprised of: 
 a ITM drum located substantially adjacent to the impression drum so as to create a nip between the impression drum and the ITM drum.    
   
   
       5 . A method for assuring media feeding, comprising: 
 pushing a sheet of media by an input feed unit to cause the media to move towards an impression drum;    determining a velocity of the input sheet unit;    detecting a change in the velocity of the input feed unit; and    determining if the media has been properly retained in media grippers substantially located on the impression drum.    
   
   
       6 . The method, as in  claim 5 , wherein the method is further comprised of: 
 allowing the media to enter into the media grippers;    pulling the media by the grippers such that the media will pull against the input feed unit;    creating a negative pulling force on the input feed unit;    detecting the change in a velocity level of the input feed unit; and    accelerating the velocity of the input feed unit so that it becomes equal to a velocity of the grippers.    
   
   
       7 . The method, as in  claim 6 , wherein the pushing step is further comprised of: 
 operating a servo motor operatively connected to the input feed unit to cause the media to move towards an impression drum.    
   
   
       8 . The method, as in  claim 6 , wherein the pulling step is further comprised of: 
 creating a pulling force that should be greater then a driving force of the input feed unit but not great enough to adversely affect the media or pull the media out of the grippers.    
   
   
       9 . The method, as in  claim 7 , wherein the detecting step is further comprised of: 
 operatively connecting the servo motor to the input feed unit;    detecting a change in velocity level of the servo motor; and    employing a servo motor controller to detect the change in the velocity of the servo motor.    
   
   
       10 . The method, as in  claim 9 , wherein the accelerating step is further comprised of: 
 operating the servo motor in order to change the velocity of the input feed unit.    
   
   
       11 . The method, as in  claim 5 , wherein the method is further comprised of: 
 the media does not properly engage with the grippers;    creating a decreased velocity of the input feed unit; and    stopping the media from moving towards the impression drum.    
   
   
       12 . The method, as in  claim 11 , wherein the step of creating a decreased velocity is further comprised of: 
 eliminating any tension force that is applied upon the input feed unit by the media.    
   
   
       13 . A program storage medium readable by a computer, tangibly embodying a program of instructions executable by the computer to perform method steps for assuring media feeding, comprising: 
 pushing a sheet of media by an input feed unit to cause the media to move towards an impression drum;    determining a velocity of the input sheet unit;    detecting a change in the velocity of the input feed unit; and    determining if the media has been properly retained in media grippers substantially located on the impression drum.    
   
   
       14 . The method, as in  claim 13 , wherein the method is further comprised of: 
 allowing the media to enter into the media grippers;    pulling the media by the grippers such that the media will pull against the input feed unit;    creating a negative pulling force on the input feed unit;    detecting the change in a velocity level of the input feed unit; and    accelerating the velocity of the input feed unit so that it becomes equal to a velocity of the grippers.    
   
   
       15 . The method, as in  claim 14 , wherein the pushing step is further comprised of: 
 operating a servo motor operatively connected to the input feed unit to cause the media to move towards an impression drum.    
   
   
       16 . The method, as in  claim 14 , wherein the pulling step is further comprised of: 
 creating a pulling force that should be greater then a driving force of the input feed unit but not great enough to adversely affect the media or pull the media out of the grippers.    
   
   
       17 . The method, as in  claim 15 , wherein the detecting step is further comprised of: 
 operatively connecting the servo motor to the input feed unit;    detecting a change in velocity level of the servo motor; and    employing a servo motor controller to detect the change in the velocity of the servo motor.    
   
   
       18 . The method, as in  claim 17 , wherein the accelerating step is further comprised of: 
 operating the servo motor in order to change the velocity of the input feed unit.    
   
   
       19 . The method, as in  claim 13 , wherein the method is further comprised of: 
 the media does not properly engage with the grippers;    creating a decreased velocity of the input feed unit; and    stopping the media from moving towards the impression drum.    
   
   
       20 . The method, as in  claim 19 , wherein the step of creating a decreased velocity is further comprised of: 
 eliminating any tension force that is applied upon the input feed unit by the media.