Patent ID: 8162312

Claim:
A sheet pick-up device of an automatic document feeder, said sheet pick-up device having functions of stopping a paper sheet from entering a sheet-feeding channel and feeding said paper sheet into said sheet-feeding channel, said sheet pick-up device comprising: a two-way clutch transmission mechanism comprising a power input shaft and a clutch gear set coaxial with said power input shaft, wherein said power input shaft is driven to rotate in either a clockwise direction or an anti-clockwise direction by a motor; a sheet pick-up arm fixedly connected to said power input shaft for transporting said paper sheet into said sheet-feeding channel; a stopper for stopping said paper sheet from entering said sheet-feeding channel; and a linking assembly connected to said power input shaft and said stopper, wherein when said power input shaft is rotated in said clockwise direction, said sheet pick-up arm is in a standby position, and said stopper is moved with said linking assembly to be in a stopping position, so that said paper sheet is stopped from entering said sheet-feeding channel, wherein when said power input shaft is rotated in said anti-clockwise direction, said sheet pick-up arm is in a sheet pick-up position, and said stopper is moved with said linking assembly to be in a non-stopping position, so that said paper sheet is allowed to be fed into said sheet-feeding channel, wherein said clutch gear set comprises: a position-changing plate sheathed around said power input shaft, and fixed on said power input shaft; a driving gear disposed on said position-changing plate, and sheathed around said power input shaft; a first switching gear disposed on said position-changing plate; a second switching gear disposed on said position-changing plate, and engaged with said driving gear; and a notched gear disposed on a rotary shaft, and having a notch in a periphery thereof, wherein when said power input shaft is rotated in said clockwise direction, said position-changing plate is rotated, so that said first switching gear is engaged with notched gear, said notched gear is rotated with said first switching gear, and said stopper is moved with said linking assembly to be in said stopping position, wherein until said notch of said notched gear is rotated to be aligned with said first switching gear, said first switching gear runs idle, wherein when said power input shaft is rotated in said anti-clockwise direction, said position-changing plate is rotated, so that said second switching gear is engaged with notched gear, said notched gear is rotated with said second switching gear, and said stopper is moved with said linking assembly to be in said non-stopping position, wherein until said notch of said notched gear is rotated to be aligned with said second switching gear, said second switching gear runs idle.