Apparatus and method for feeding print media from a stack

摘要

The sheet feeder includes a tray having a pusher mechanism mounted at a rear portion and a feeder mechanism mounted at a forward portion. The pusher mechanism is driven through a spring wrap clutch which includes a ratchet which engages a pawl mounted on the feeder mechanism. When the feeder mechanism is in a first position the pawl is disengaged from the ratchet and the clutch is free to rotate and engage the pusher mechanism which advances the stack of sheets against the feeder mechanism, driving the feeder mechanism back to a second position where the pawl engages the ratchet, disengaging the spring wrap clutch and halting the pusher mechanism. As sheets are fed from the stack a spring urges the feeder mechanism back towards the first position, disengaging the ratchet and engaging the clutch and repeating the cycle. A spring maintains a substantially constant normal force between the feeder mechanism and the stack as the feeder mechanism moves between the first and second positions.