Method for controlling stack-advancing in a reproduction apparatus

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.

1 . 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.  
   
   
       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 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.  
   
   
       6 . The method of  5 , 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.  
   
   
       7 . A method for controlling stack advancing in a reproduction apparatus, comprising: determining maximum platform displacement, N·sub·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·sub·K, that occurred during feeding said K sheets; and, calculating a paper low displacement  N ·sub· L=N ·sub· T−N ·sub· K  and storing N·sub·L in memory.  
   
   
       8 . The method of  claim 7 , further comprising initializing N·sub·L to a nominal value and storing it in memory.  
   
   
       9 . The method of  claim 7 , wherein reaching N·sub·L initiates switching over to feed from another stack loaded with the same sheet attributes.  
   
   
       10 . The method of  claim 7 , comprising initializing N·sub·L if a renewal of the stack occurs.  
   
   
       11 . The method of  claim 7 , further comprising initializing N·sub·L in response to a change of sheet attributes.  
   
   
       12 . The method of  claim 7 , further comprising initializing N·sub·L to a nominal value, storing it in memory, and replacing it with a determined N·sub·L for that stack.  
   
   
       13 . The method of  claim 7 , further comprising driving said platform with a stepper motor, and expressing said displacement as stepper motor counts.  
   
   
       14 . 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·sub·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·sub·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·sub·K; replacing said nominal number of steps with  N ·sub· T−N ·sub· K  in memory.  
   
   
       15 . The method of  claim 14 , wherein reaching N·sub·L initiates switching over to feed from another stack loaded with the same sheet attributes.  
   
   
       16 . The method of  claim 14 , comprising initializing N·sub·L if a renewal of the stack occurs.  
   
   
       17 . The method of  claim 14 , further comprising initializing N·sub·L in response to a change of sheet attributes.  
   
   
       18 . The method of  claim 14 , further comprising initializing N·sub·L to a nominal value, storing it in memory, and replacing it with a determined N·sub·L for that stack.  
   
   
       19 . A method for controlling sheet stack advancing, comprising: 
 a) determining stack position corresponding to a predetermined number of sheets remaining in a sheet supply to indicated a paper low nominal valve; and    b) controlling sheet feeding in response thereto.