Vacuum sheet feeder

Abstract

A vacuum feeding mechanism for a document handling apparatus, the feeding mechanism comprising: an adjustable pick for separating a stack of documents from a downstream transport system; a rotatable wheel connected to a vacuum port and operable to pull a document by suction from the top of the stack toward the wheel and move the document over the pick to the downstream transport system; the wheel and the pick being separated by a clearance distance; means for determining adjustment coordinates in dependence upon characteristics of a document in the stack; wherein the position of the pick is automatically adjustable in two independent dimensions in dependence upon said adjustment coordinates.

1 . A vacuum feeding mechanism for a document handling apparatus, the feeding mechanism comprising:
 an adjustable pick for separating a stack of documents from a downstream transport system;   a rotatable wheel connected to a vacuum port and operable to pull a document by suction from the top of the stack toward the wheel and move the document over the pick to the downstream transport system;   the wheel and the pick being separated by a clearance distance;   means for determining adjustment coordinates in dependence upon characteristics of a document in the stack;   wherein the position of the pick is automatically adjustable in two independent dimensions in dependence upon said adjustment coordinates.   
   
   
       2 . A vacuum feeding mechanism according to  claim 1  wherein the adjustment coordinates are determined also in dependence upon the position of the pick relative to the vacuum wheel and the desired clearance distance. 
   
   
       3 . A vacuum feeding mechanism according to  claim 1  wherein the desired clearance distance is calculated as a function of the thickness of the document. 
   
   
       4 . A vacuum feeding mechanism according to  claim 1  wherein the desired clearance distance is calculated as a function of the flexure characteristics of the document. 
   
   
       5 . A vacuum feeding mechanism according to  claim 1  further comprising means to automatically adjust the suction applied by the wheel to the top document of the stack. 
   
   
       6 . A vacuum feeding mechanism for a document handling apparatus, the feeding mechanism comprising:
 an adjustable pick for separating a stack of documents from a downstream transport system;   a rotatable wheel connected to a vacuum port and operable to pull a document by suction from the top of the stack toward the wheel and move the document over the pick to the downstream transport system;   the wheel and the pick being separated by a clearance distance;   means for determining adjustment coordinates in dependence upon characteristics of a document in the stack;   wherein the suction applied by the wheel to the top document of the stack is automatically adjustable in dependence upon said adjustment coordinates.   
   
   
       7 . A vacuum feeding mechanism according to  claim 6  wherein the suction adjustment comprises adjustment of the strength of the suction. 
   
   
       8 . A vacuum feeding mechanism according to  claim 6  wherein the suction adjustment comprises adjustment of the spread of suction application across the width of the document. 
   
   
       9 . A vacuum feeding mechanism according to  claim 6  further comprising a feedback loop. 
   
   
       10 . A vacuum feeding mechanism according to  claim 9  wherein the feedback includes data corresponding to any one or any combination of the following factors:
 a) the delay between a request for a document being made and arrival of the document at a position downstream;   b) the time or distance between successive documents;   c) whether two or more documents are fed together;   d) whether two or more documents overlap.   
   
   
       11 . A vacuum feeding mechanism according to  claim 10  wherein at least one of the factors is detected by a sensor located downstream of the feeding mechanism. 
   
   
       12 . A vacuum feeding mechanism according to  claim 9  wherein the initial settings for the pick position are automatically calculated from parameters of the documents. 
   
   
       13 . A vacuum feeding mechanism according to  claim 9  wherein the initial settings for the vacuum port are automatically calculated from parameters of the documents. 
   
   
       14 . A vacuum feeding mechanism according to  claim 9  wherein the initial settings are stored with other job settings for a particular feed run. 
   
   
       15 . A vacuum feeding mechanism according to  claim 11  wherein the parameters comprise details of one or more of weight, thickness and flexibility of the documents. 
   
   
       16 . A vacuum feeding mechanism according to  claim 11  wherein the parameters are preset as standard settings for an operator to choose. 
   
   
       17 . A vacuum feeding mechanism according to  claim 11  wherein at least one of the parameters is measured prior to operation of a feed run. 
   
   
       18 . A vacuum feeding mechanism according to  claim 11  wherein the initial settings are stored for each job and can be used each time the same job is to be re-run.