Patent ID: 7549627

Claim:
An automatic document feeder comprising: a housing unit; a driving unit including a driving wheel; a clutch unit disposed in said housing unit and including a first wheel driven by said driving wheel, a second wheel disposed in proximity to said first wheel, a resilient member interposed between said first and second wheels, and a driving rod, said first wheel having an engagement surface formed with a plurality of first engaging portions, said second wheel having an engagement surface formed with a plurality of second engaging portions aligned respectively with said first engaging portions of said first wheel, said resilient member being interposed between said engagement surfaces of said first and second wheels so as to bias said first and second wheels to move away from each other, said driving rod having a thick rod portion and a thin rod portion and being movable between a connecting position whereat said second wheel comes into contact with said thick rod portion of said driving rod and whereat said second engaging portions of said second wheel engage respectively said first engaging portions of said first wheel so as to allow for transfer of rotation of said first wheel to said second wheel, and a disconnecting position whereat said second wheel comes into contact with said thin rod portion of said driving rod and whereat said second engaging portions of said second wheel are disengaged respectively from said first engaging portions of said first wheel so as to prevent transfer of rotation of said first wheel to said second wheel; a first roller unit driven by said second wheel; a second roller unit driven by said second wheel; and a third roller unit driven by said second wheel.