Document feeder

Abstract

A document feeder includes a housing, a sheet pick-up arm and a stopper. The housing includes a sheet feeding path for placing paper sheets thereon. The sheet pick-up arm is movable between a first position and a second position. The sheet pick-up arm has a protrusion structure. The stopper is disposed under the sheet feeding path and includes a pivotal portion and a sheet stop portion. The sheet stop portion has a hooking part corresponding to the protrusion structure. When the sheet pick-up arm is moved to the first position, the protrusion structure is located in the swing track of the hooking part to restrain the swing range of the sheet stop portion. When the sheet pick-up arm is moved to the second position, the protrusion structure is deviated from the swing track of the hooking part to permit free swing of the sheet stop portion.

1 . A document feeder comprising:
 a housing including a sheet feeding path for placing paper sheets thereon;   a sheet pick-up arm pivotally mounted above said sheet feeding path and movable between a first position and a second position, wherein said sheet pick-up arm has a protrusion structure; and   a stopper disposed under said sheet feeding path and comprising a pivotal portion and a sheet stop portion, said sheet stop portion having a hooking part corresponding to said protrusion structure,   wherein said protrusion structure is located in the swing track of said hooking part to restrain the swing range of said sheet stop portion when said sheet pick-up arm is moved to said first position, and said protrusion structure is deviated from the swing track of said hooking part to permit free swing of said sheet stop portion when said sheet pick-up arm is moved to said second position.   
   
   
       2 . The document feeder according to  claim 1  where said sheet pick-up arm comprises a sheet pick-up roller and a sheet separation roller. 
   
   
       3 . The document feeder according to  claim 1  further comprising a driving shaft for driving said sheet pick-up arm, wherein said sheet separation roller is sheathed around the driving shaft. 
   
   
       4 . The document feeder according to  claim 1  wherein said stopper further comprises a loading portion, said loading portion and said sheet stop portion being arranged on opposite sides of said pivotal portion, wherein the torque applied on said loading portion is greater than the torque applied on said sheet stop portion with said pivotal portion serving as a fulcrum. 
   
   
       5 . The document feeder according to  claim 1  further comprising a torsion spring having an end sustained against said sheet stop portion.