This invention relates in general to recirculating document feeders, and more particularly to a recirculating document feeder for use with an electrostatographic apparatus for producing precollated or post-collated simplex or duplex copies from simplex or duplex original documents.
Electrostatographic reproduction apparatus typically produce copies of original information on receiver members, such as cut sheets of plain bond paper for example. Such information may be formed on one side of a receiver sheet (referred to as a simplex copy) or on both sides of a receiver sheet (referred to as a duplex copy). In certain commercial reproduction apparatus capable of producing duplex copies, selected information is electrostatographically reproduced sequentially on the first sides of respective receiver sheets which are thereafter collected in an intermediate tray. Such sheets are then transported sequentially from the intermediate tray back through the apparatus where other selected information is reproduced respectively on the second sides of such sheets. This reproduction procedure is commonly referred to as "two-pass" duplex copying.
A recirculating document feeder for use with an electrostatographic reproduction apparatus capable of making pre-collated or post-collated simplex or "two-pass" duplex copies from simplex or duplex original documents is shown in U.S. Pat. No. 4,712,214 (issued Dec. 22, 1987, in the name of Randall). While such feeder represents a significant advancement over prior recirculating feeders, it requires accurate control over the operation of diverters necessary to direct the original documents in appropriate paths to accomplish the various desired modes of operation. Moreover, the document turnover mechanism subjects the document sheets to a degree of handling which can potentially damage the sheets. Since the document sheets are often fragile originals, such potential damage must be avoided if at all possible.