Automatic document feeder having an input tray paper stop and pick mechanism

An automatic document feeder for a computer input device having a medium receiving and supporting surface, comprising:

• a modular housing having defined therewithin a medium path extending between an upwardly extending input tray and an upwardly extending output tray via the medium receiving and supporting surface of the computer input device, said housing further having disposed on its underside a document backer moveable between a raised position to permit a document sheet to pass thereunder onto and off the supporting surface in a substantially friction free manner without any electrostatic build up and a lowered position overlying the document sheet to facilitate document scanning purposes on the receiving and supporting surface of the computer input device;
• a paper pick and transport mechanism mounted within said housing and protruding through a center portion of said input tray for picking in seriatim individual ones of a plurality of medium sheets stacked in the input tray and for transporting each individual sheet toward the receiving and supporting surface of the computer input device;
• and
• a lift cam mechanism coupled to said document backer to facilitate the sequencing of raising the document backer to said raised position, advancing said document sheet from said paper pick and transport mechanism onto the receiving and supporting surface of the computer input device, lowering the document backer in an overlaying relationship onto said document sheet to facilitate document scanning, raising the document backer to a raised position, ejecting the document sheet from said supporting surface in a reliable sheet feeding manner, and lowering the document backer onto the supporting surface in a ready position in anticipation of covering another document sheet.