Duplex automatic sheet feeder

Abstract

In a duplex automatic sheet feeder, a first passageway is connected to a sheet input tray for storing sheets. A sheet feeding mechanism feeds the sheets one by one to the first passageway. A second passageway is connected to the first and third passageways and has an image processing region. A fourth passageway is connected to the third passageway and the second passageway. A fifth passageway is connected to the third passageway and a duplex sheet output tray. A guiding mechanism located at a connection portion between the third and fifth passageways selectively guides the sheet from the third passageway to the fifth passageway. A sheet detector located at the third passageway detects the sheet moving through the third passageway. A transporting mechanism transports the sheet from the first passageway to the duplex sheet output tray sequentially through the second, third, fourth, third and fifth passageways.

1 . A duplex automatic sheet feeder, comprising:
 a sheet input tray for storing a plurality of sheets;   a first passageway connected to the sheet input tray;   a sheet feeding mechanism for feeding the sheets one by one to the first passageway;   a second passageway, which is connected to the first passageway and has an image processing region;   a third passageway connected to the second passageway;   a fourth passageway connected to the third passageway and the second passageway;   a fifth passageway connected to the third passageway;   a sheet output tray connected to the fifth passageway;   a guiding mechanism, located at a connection portion between the third passageway and the fifth passageway, for selectively guiding the sheet from the third passageway to the fifth passageway;   a sheet detector, located at the third passageway, for detecting the sheet moving through the third passageway; and   a transporting mechanism for transporting the sheet from the first passageway to the sheet output tray sequentially through the second passageway, the third passageway, the fourth passageway, the second passageway, the third passageway and the fifth passageway.   
   
   
       2 . The feeder according to  claim 1 , wherein the third passageway is connected to the sheet output tray, and in a simplex mode, the transporting mechanism may further transport the sheet from the first passageway to the sheet output tray sequentially through the second passageway and the third passageway. 
   
   
       3 . The feeder according to  claim 2 , wherein an outlet of the third passageway is farther from the sheet output tray than an outlet of the fifth passageway. 
   
   
       4 . The feeder according to  claim 1 , further comprising a simplex sheet output tray, connected to the third passageway, for transporting the sheet from the first passageway to the simplex sheet output tray sequentially through the second passageway and the third passageway in a simplex mode. 
   
   
       5 . The feeder according to  claim 4 , wherein the simplex sheet output tray is located at a level higher than the sheet output tray. 
   
   
       6 . The feeder according to  claim 1 , wherein the guiding mechanism further guides the sheet from the third passageway to the fourth passageway. 
   
   
       7 . The feeder according to  claim 1 , wherein the guiding mechanism further guides the sheet from the second passageway to the third passageway. 
   
   
       8 . The feeder according to  claim 1 , further comprising:
 an elastic guide for guiding the sheet from the third passageway to the fourth passageway.   
   
   
       9 . The feeder according to  claim 1 , further comprising:
 a sub-guiding mechanism, which may swing to guide the sheet from the third passageway to the fourth passageway or from the second passageway to the third passageway.