Abstract: In recirculatively precollatively copying a set of plural original documents onto both sides of copy sheets to produce a desired plural number precollated duplex copy sheet sets, by normally copying the documents only once in each copying circulation of the document set onto one side of copy sheets to form a duplexing buffer and copying other documents onto the opposite sides of the buffer copies to form duplex precollated copies, the improvement comprising: counting the number of documents in the document set and determining that the number of documents is only two or three, and in response to the determination, automatically switching the mode of copying of the documents to a higher productivity two or three document set mode in which plural identical consecutive copies are first made from only one document (the first document page) by halting the first copying circulation of the document set to copy only the one document, and forming the buffer from these plural identical copies and then skipping the copyi

Abstract: In recirculatively precollatively copying a set of plural simplex original documents onto both sides of copy sheets to produce a desired plural number precollated duplex copy sheet sets, by normally copying the documents only once in each copying circulation of the document set, and by forming a buffer set of copies of alternate document pages being duplexed which buffer set copies are printed on only one side, and temporarily stored in a duplex store and by copying alternate documents onto the opposite sides of the buffer set copies in proper sequence to form collated duplex copy sets, and wherein said documents are all copied unidirectionally in reverse (N to 1) page order, the improvement comprising: counting the number of documents in the document set and determining that the number of documents is more than three but less than approximately ten, and in response to that determination, automatically switching the mode of copying the document sheets to a higher productivity small document set mode including