Method for controlling stack-advancing in a reproduction aparatus

Abstract

The present invention relates to a method for providing paper stack level calibration in a reproduction apparatus. According to various aspects of the invention, methods are provided for continuous feeding with a transition from one supply to another, and leaving a controlled number of sheets in the prior supply.

What is claimed is:  
     
         1 . A method for controlling sheet stack advancing, comprising: 
 determining a distance of a platform relative to a feedhead corresponding to a predetermined number of sheets to be left in a sheet supply, said sheets resting upon said platform;    switching to another sheet supply when said platform is said distance from said feedhead thereby leaving said predetermined number of sheets in said sheet supply, said predetermined number remaining unchanged regardless of a sheet thickness.    
     
     
         2 . The method of  claim 1 , further comprising driving said platform with a stepper motor, and expressing said distance as stepper motor counts.  
     
     
         3 . The method of  claim 1 , further comprising determining said distance prior to said platform being at said distance relative to said feedhead.  
     
     
         4 . The method of  claim 1 , further comprising storing said distance in memory.  
     
     
         5 . A method for controlling sheet stack advancing, comprising: 
 determining a sheet thickness by measuring a displacement of a platform corresponding to a known number of sheet feeds by said feedhead, said sheets resting upon said platform;    determining a distance of said platform relative to a feedhead corresponding to a predetermined number of sheets having said sheet thickness to be left in a sheet supply;    switching scheduling of future feeds to another sheet supply when said platform is said distance from said feedhead.    
     
     
         6 . The method of  claim 5 , further comprising driving said platform with a stepper motor, and expressing said distance as stepper motor counts.  
     
     
         7 . The method of  claim 5 , further comprising determining said distance prior to said platform being at said distance relative to said feedhead.  
     
     
         8 . The method of  claim 5 , further comprising storing said distance in memory.  
     
     
         9 . A method for controlling sheet stack advancing, comprising: 
 determining a maximum travel of a platform and storing it in a memory, said sheet stack resting upon said platform;    advancing said platform with a motor from a bottom-most to a top-most height position and performing sheet separating and feeding;    determining a current platform travel before every feed;    saving said current platform travel in said memory and comparing said current platform travel with a nominal platform travel, and updating said maximum travel in memory each time said platform is completely emptied of sheets.    
     
     
         10 . The method of  9 , further comprising generating an error signal if a difference between said current platform travel and said nominal platform travel is greater than a predetermined value.  
     
     
         11 . A method for controlling stack advancing in a reproduction apparatus, comprising: 
 determining maximum platform displacement, N T , and storing it in memory, a stack of sheets resting on said platform;    advancing said platform and performing sheet separating and feeding for K sheets;    recording a current platform displacement, N K , that occurred during feeding said K sheets; and,    calculating a paper low displacement N L =N T −N K  and storing N L  in memory.    
     
     
         12 . The method of  claim 11 , further comprising initializing N L  to a nominal value and storing it in memory.  
     
     
         13 . The method of  claim 11 , wherein reaching N L  initiates switching over to feed from another stack loaded with the same sheet attributes.  
     
     
         14 . The method of  claim 11 , comprising initializing N L  if a renewal of the stack occurs.  
     
     
         15 . The method of  claim 11 , further comprising initializing N L  in response to a change of sheet attributes.  
     
     
         16 . The method of  claim 11 , further comprising initializing N L  to a nominal value, storing it in memory, and replacing it with a determined N L  for that stack.  
     
     
         17 . The method of  claim 11 , further comprising driving said platform with a stepper motor, and expressing said displacement as stepper motor counts.  
     
     
         18 . A method for controlling stack-advancing in a reproduction apparatus, comprising: 
 driving a platform in steps with a lifting motor and performing sheet separating and feeding;    initializing a paper-low displacement, N L , of said platform to a nominal number of said steps and storing it in memory;    determining a number of steps of said lifting motor to achieve movement from a bottom position to a top position of said platform, N T , and storing it in a memory;    separating and feeding K sheets and recording in memory an actual number of said steps corresponding to feeding said K sheets, N K ;    replacing said nominal number of steps with N T -N K  in memory.    
     
     
         19 . The method of  claim 18 , wherein reaching N L  initiates switching over to feed from another stack loaded with the same sheet attributes.  
     
     
         20 . The method of  claim 18 , comprising initializing N L  if a renewal of the stack occurs.  
     
     
         21 . The method of  claim 18 , further comprising initializing N L  in response to a change of sheet attributes.  
     
     
         23 . The method of  claim 18 , further comprising initializing N L  to a nominal value, storing it in memory, and replacing it with a determined N L  for that stack.  
     
     
         24 . A method for controlling sheet stack advancing, comprising: 
 determining a distance of a platform relative to a feedhead corresponding to a predetermined number of sheets K to be left in a sheet supply, said sheets resting upon said platform;    determining a number of feeds J already scheduled from said sheets when said platform is said distance from said feedhead;    scheduling up to K−J more feeds from said sheets, and    switching further scheduling to another sheet supply.