Auto-document feeder and image reading apparatus

Abstract

An auto-document feeder includes: a paper feeding section configured to feed original documents one by one; a first feeding section configured to feed the fed original document through a first feeding path; a second feeding section configured to feed the fed original document through a second feeding path; a third feeding section configured to alternately nip one by one the fed original documents; a determining section configured to determine that the original document is nipped by the third feeding section; and a document diverting and feeding section configured to alternately divert and feed, into the first feeding path and the second feeding path, the fed original documents and, if the preceding original document is present, after the preceding original document is detected by the determining section, feed the following original document into the first or second feeding path into which the preceding original document is not fed.

1 . An auto-document feeder comprising:
 a paper feeding section configured to feed sheets of an original document one by one, from which images are read by an image reading section;   a first feeding section configured to feed the original document, which is fed by the paper feeding section, in a direction of the image reading section through a first feeding path;   a second feeding section configured to feed a different sheet of the original document, which is fed by the paper feeding section, in the direction of the image reading section through a second feeding path different from the first feeding path;   a third feeding section configured to alternately nip one by one the original documents fed by the first feeding section and the second feeding section and feed the original documents to the image reading section;   a determining section configured to determine that the original document is nipped by the third feeding section; and   a document diverting and feeding section configured to alternately divert and feed the original documents, which are fed by the paper feeding section, into the first feeding path and the second feeding path and, if a preceding original document is present, after the preceding original document is detected by the determining section, feed a following original document into the first or second feeding path into which the preceding original document is not fed.   
     
     
         2 . The feeder according to  claim 1 , wherein the third feeding section includes a pair of feeding rollers and alternately nips one by one, between the feeding rollers, the original documents fed by the first feeding section and the second feeding section and feeds the original documents to the image reading section. 
     
     
         3 . The feeder according to  claim 2 , wherein, a sensor provided between the feeding rollers and the image reading section detects the original document fed by the feeding rollers, whereby the determining section determines that the original document is nipped by the third feeding section. 
     
     
         4 . The feeder according to  claim 3 , wherein
 the document diverting and feeding section includes registration rollers configured to align leading ends of the original documents fed by the paper feeding section and feed the original documents into the first feeding path and the second feeding path, and   if the preceding original document is present, after the preceding original document is detected by the determining section, the registration rollers feed a following document into the first feeding path or the second feeding path.   
     
     
         5 . The feeder according to  claim 4 ; wherein the document diverting and feeding section includes a gate configured to alternately divert the original documents, which are fed by the registration rollers, to the first feeding path and the second feeding path. 
     
     
         6 . The feeder according to  claim 5 , wherein the paper feeding section includes:
 a tray on which plural original documents are stacked;   a pickup roller configured to pick up the original documents stacked on the tray; and   separating rollers configured to separate and feed the original documents one by one picked up by the pickup roller.   
     
     
         7 . The feeder according to  claim 6 , wherein
 the document diverting and feeding section includes a second detecting section provided between the registration rollers and the separating rollers and configured to detect that the original document fed by the separating rollers reaches the registration rollers and passes the registration rollers, and   the pickup roller and the separating rollers start feeding of the following original document after the second detecting section detects that the preceding original document passes the registration rollers.   
     
     
         8 . The feeder according to  claim 1 , wherein
 the first feeding section includes first intermediate feeding rollers along the first feeding path,   the second feeding section includes second intermediate feeding rollers along the second feeding path, and   the first intermediate feeding rollers and the second intermediate feeding rollers feed the original document, which is fed from the first feeding path or the second feeding path, to the image reading section in cooperation with the third feeding section.   
     
     
         9 . The feeder according to  claim 8 , wherein, if the preceding original document is present in one of the first feeding path or the second feeding path, the first intermediate feeding rollers and the second intermediate feeding rollers feed, after putting the following original document present in the other feeding path on standby, a following original document. 
     
     
         10 . An image reading apparatus comprising:
 an image reading section configured to read an image of an original document;   a paper feeding section configured to feed the original documents one by one, from which the images are read by the image reading section;   a first feeding section configured to feed the original document, which is fed by the paper feeding section, in a direction of the image reading section through a first feeding path;   a second feeding section configured to feed the original document, which is fed by the paper feeding section, in the direction of the image reading section through a second feeding path different from the first feeding path;   a third feeding section configured to alternately nip one by one the original documents fed by the first feeding section and the second feeding section and feed the original documents to the image reading section;   a detecting section configured to detect that the original document is nipped by the third feeding section; and   a document diverting and feeding section configured to alternately divert and feed the original documents, which are fed by the paper feeding section, into the first feeding path and the second feeding path and, if a preceding original document is present, after the preceding original document is detected by the detecting section, feed a following original document into the first or second feeding path into which the preceding original document is not fed.