Feeder system with independent control of rollers

Abstract

The present subject matter relates to a feed roller system for high speed image scanning equipment, which improves the feeding of documents, and in particular, thin or ultra-thin documents, into the scanner equipment. The feed roller system comprises a pick roller and a feed roller, each associated with its own clutch, allowing the pick roller and feed roller to be selectively driven together, independently, and/or not at all. Initially, both rollers are driven to feed a document. Drive to the pick roller is disabled by the pick roller clutch when the leading edge of the document reaches a gap control sensor, downstream of the rollers. Drive to the feed roller continues until it is disabled by the feed roller clutch when the leading edge of the document reaches a page entry sensor, downstream of the gap control sensor and the first transport rollers. The first transport rollers continue to feed the document, while the pick roller and the feed roller are disengaged, thus preventing overfeeding or misfeeding by the pick roller and/or feed roller.

1 . A sheet feeder apparatus, comprising:
 a pick roller for advancing a document from a stack;   a feed roller for feeding the document; and   a drive system for selectively driving the pick roller and the feed roller, wherein the drive system is adapted to selectively drive the feed roller and the pick roller together, to selectively drive the feed roller independent of the pick roller, and to selectively disengage drive to both the feed roller and the pick roller.   
     
     
         2 . The apparatus of  claim 1 , wherein the drive system comprises a first clutch for selectively disengaging drive to the pick roller. 
     
     
         3 . The apparatus of  claim 2 , wherein the first clutch is operable responsive to a first sensor which senses the document. 
     
     
         4 . The apparatus of  claim 3 , wherein the drive system comprises a second clutch for selectively disengaging drive to the feed roller. 
     
     
         5 . The apparatus of  claim 4 , wherein the second clutch is operable responsive to a second sensor which senses the document. 
     
     
         6 . The apparatus of  claim 5 , further comprising a pair of transport rollers. 
     
     
         7 . The apparatus of  claim 5 , wherein at least one motor selectively drives the pick roller and the feed roller. 
     
     
         8 . The apparatus of  claim 6 , wherein at least one motor selectively drives the pick roller, the feed roller and the pair of transport rollers. 
     
     
         9 . An apparatus for feeding documents from a stack of documents to a pair of transport rollers, each of the documents having a leading edge, the apparatus comprising:
 a pick roller;   a feed roller downstream of the pick roller;   a first sensor downstream of the feed roller for sensing the documents; and   a second sensor downstream of the pair of transport rollers;   the pick roller and the feed roller adapted to be driven together wherein the pick roller advances a first document towards the feed roller and the feed roller advances the first document to the first sensor;   wherein when the leading edge of the first document reaches the first sensor, drive to the pick roller is halted, and when the leading edge of the first document reaches the second sensor, drive to the feed roller is halted.   
     
     
         10 . A method for feeding documents from a stack of documents, each of said documents having a leading edge, said method comprising the steps of:
 aligning a pick roller, a feed roller downstream of the pick roller, and a first sensor downstream of the feed roller, and a second sensor downstream of the first sensor;   driving the pick roller and the feed roller together;   advancing a first document from the pick roller to the feed roller;   advancing the first document from the feed roller to the first sensor and sensing the first document via the first sensor;   disengaging drive to the pick roller while the first document is being sensed by the first sensor;   advancing the first document to the second sensor and sensing the first document via the second sensor; and   disengaging drive to the feed roller while the first document is being sensed by the first sensor.   
     
     
         11 . The method of  claim 10 , further comprising the step of re-engaging drive to the pick roller and the feed roller to advance a second document after the first document clears the first sensor. 
     
     
         12 . (canceled) 
     
     
         13 . A sheet feeder apparatus for feeding documents to document transport roller of a device, comprising:
 a pick roller for advancing a document from a stack;   a feed roller proximate the pick roller for feeding the document into the document transport path; and   a drive system for driving the pick roller and the feed roller, the drive system includes a first clutch for selectively disengaging drive to the pick roller, and a second clutch for selectively disengaging drive to the feed roller;   wherein the drive system is adapted to selectively drive the feed roller and the pick roller together, to selectively drive the feed roller independent of the pick roller, and to selectively disengage drive to both the feed roller and the pick roller.   
     
     
         14 . A method for feeding documents from a stack of documents to a document transport roller of a device, each of the documents having a leading edge, the method comprising the steps of:
 driving a pick roller and a feed roller together;   advancing a first document from the pick roller to the feed roller;   advancing the first document from the feed roller to a first sensor and sensing the first document via the first sensor;   disengaging drive to the pick roller when the first document is sensed by the first sensor; advancing the first document to a second sensor and sensing the first document via the second sensor; and   disengaging drive to the feed roller when the first document is sensed by the second sensor.   
     
     
         15 . The method of  claim 14 , further comprising the step of re-engaging drive to the pick roller and the feed roller to advance a second document after the first document clears the first sensor. 
     
     
         16 . (canceled)