Sheet feeding and separating apparatus with stack force relief/enhancement

摘要

A retard feeder and separator apparatus adapted to sense the threat of a misfeed or multifeed and adjust the stack normal force of a feed belt against a stack of sheets accordingly. The apparatus includes a movable frame on which is mounted a sheet separating feed belt, a retard roll that forms a retard nip with the separating feed belt, and a stack force relief sensor. The sensor detects the lead edge of a sheet fed from a stack as it reaches the retard nip and causes a solenoid connected to the frame to trigger and move the frame slightly. The frame movement relieves the stack normal force of the feed belt against the stack from a high value to a low value while the sheet continues to be fed from the stack by the force in the retard nip and the lessened stack normal force. Alternatively, if the sensor does not sense a sheet within a predetermined period of time, the stack normal force will be increased to the original high value.