CA1117154A - Duplex/simplex precollation copying system - Google Patents

Abstract

DUPIIEX/SIMPLEX PRECOLLATION COPYING SYSTEM

ABSTRACT OF THE DISCLOSURE
A copying system for copying either duplex or simplex original document sets as pre-collated copy sets, utilizing a document handling system providing selective automatic recirculative pre-collation copying of either duplex or simplex document sheets, with selective automatic sheet inversion. Also described is an integral sheet stack normal force/iogger unit for continuous and simultaneous top loading and bottom feeding from either opposite or common directions from a stack of document or copy sheets.

Description

SUMMARY AND BACKGROUND OF 'rHE INVENTI0 CI TATI ON OF ART
The present invention xelates to improved pre-collation copying systems and to improved automatic document handling systems therefor providing pre-collation copying from duplex documents.
As xerographic and other copiers increase in speed, and become more automatic, it is increasingly important to provide higher speed yet more reliable and more automatic handling of both the copy sheets and the individual oriylnal documents being copied. Yet, it is desired to accommodate original documents and copy sheets which vary widely in size, weight, thickness, material, condition, humidity, age, etc.
It is desirable to automatically handle such individual document and copy sheets in rapid succession with relatively compact and inexpensive sheet handling apparatus. Further, it is desirable to provide sheet handling systems and apparatus which accommodates different sheet orientations and movement directions so as to be able to optimlze and compact the design of the copier and/or its document handling unit. The providing of duplex copying capabilities and/or a pre-collation copy system greatly complicates and increases these copier sheet handling difficulties.
The term "duplex copying" may be more specifi-cally defined into several different, individually known, copying modes. In duplex/duplex copying, both sides of a duplex document sheet (which has images on both sides) are copied onto both sides of a single copy sheet. In duplex/
simplex copying, both sides of a duplex document are copied onto only one side of two successive copy sheets. In simplex/duplex copying, the images on one side of two

- 2 -successive sLmplex documents are placed on opposite sides of a single copy sheet. In the printing industry, as opposed to the copier industry, two-sided copying may be referred to as "backing-up" rather than duplex copying.
In a set of duplex documents or copy sheets, pages 1, 3, 5, etc., will typically appear on one side, with pages 2, 4, 6, etc., on the other side. Thus, they may be respectively referred to as the "odd order" and "even order" sides.
~ he duplex copying o~ the copy sheets for duplex/
duplex or simplex/duplex copying may be done by first making a set of simplexed copy sheets (printed only on their first sides) temporarily storing those simplex copy sheets in a tray, and then feeding them back through the copying processor for a second pass printing of the opposite order document images on the opposite sides of the copy sheets. Such systems may be referred to as sequential or dual pass duplexing systems.
Examples of such systems for handling the copy sheets being duplexed are shown in U. S. Patents ~os. 3,615,129, issued October 26, 1971, to W. A. Drawe, et al., and 3,645,615, issued February 29, 1972, to M. R. Spear, Jr., and in the Xerox*
40~0 and 4500 Copiers. Of particular interest as disclosing the preferred simplex/duplex pre-collation copying system disclosed herein is a pending U. S. Patent No. 4,116,158 issued September 26, 1978, J. A. Adamek et al.. Column 7, first par-agraph thereof discusses duplex/duplex ~opying. These dual pass duplex systems have the advantage of being able to utilize a single, conventional, imaging station, transfer station, and processor for bot:h sides of the copies.

Alternatively, a single pass or sLmultaneous * trade mark ~ '7~.54 duplex system may be used in which unfused images are trans-fexred to both sides of the copy sheet in a single pass, simultaneously or in immediate sequence, and the fi~st and second sides of each document are copied simultaneously or in immediate sequence (serially). An example of such a single pass duplex system is disclosed, for example, in U. S. Patent 3,844,654 issued Octobex 29, 1975 to J. Guenther and the art cited therein. However, such systems typically disadvantageously require two separale imaging, image development, and transfer systems.
The present invention is particularly directed to pre-collation duplex copying systems in which the image sources are a set of original duplex document sheets, with images on both sides thereof, in which these duplex documents are automatically multiply recirculated with automatic exposure of both sides of the documents so as to provide pre-collated copy sets therefrom.
A highly desirable feature for a copier is to provide automatic document recirculation for pre-collation copying. As discussed, for example, in detail in U. S.
Patent No. 3,963,345 issued June 15, 1976, to D. J. Stemmle, et al., at Column 1-4, such pre-collation copying systems provide a number of important advantages. The copies exit the copier in pre-collated sets, and do not require subsequent sorting in a sorter or collator. Any desired number of such copy sets may be made by making a corres-ponding number of recirculations of the document set in collated order past a copying station and copying each document once each time it recircuiates. On-line finishing and/or removal of completed copy sets may be provided while additional copy sets are beiny made from the same documen~
set.
However, a disadvantage of pre-collation copying systems is this fact that the documents must all be repeatedly circulated and repeatedly individually copied the number of times equivalent to the desired number of copy sets. Thus, for example, to make 10 copy sets of a 5 page simplex doc~ent set or book, one copy at a time would be made of each of the 5 document pages in this order:
Pages 1, 2, 3, 4, 5; 1, 2, 3, 4, 5, etc.; repeated a total of 10 times (10 circulations) to make the desired 10 copy sets. ~For bi-directional pre-collation copying this document copying sequence would, instead, be 1, 2, 3, 4, 5;
5, 4, 3, 2, 1; 1, 2, 3, 4, 5; etc~] Thus, it may be seen that increased document handling is necessitated fora pre-collation copying system, as compared to a conventional post-collation copying system in which all the desired copies are made at one time from each document page and collated subsequently. In such a post-collation copying system, the document set need only be circulated once to fi~l the bins o the copy sheet sorter or collator with the number of copy sets desired (limited in number, however, by the number of available bins).
The increased document handling required for a pre-collation copying system increases the liklihood of document damage or wear, and particularly aggravates the problems of document separation where the individual documents must be separated from the remainder of the docu-ments in the document set for each recirculation thereof.
Thus, it is highly desirable to have a simple and reliable document handli~g system and recirculation path ~or the document in all modes of operation.
The present invention is intended to overcome or minimize the above-discussed pro~lems and disadvantages and provide the advantages of pre-collation copying. It provides a simple, compact, automatic pre-collation document handling system, in which the document set may be malntained in a compact manner, and recirculated in a short and simple document handling path, to minimize document damage and to maximize the ability to reliably multiply circulate and copy different or defective documents. The system disclosed herein is particularly suitable for, and compatible with, conventional copier platens and optics systems. It is also suitable for use as a removable or auxilary document handling system, removably overlying an existing or conventional copier platen to selectively allow use of that same platen and its associated optics for manual or other non-pre-collation copying. However, it is not limited thereto.
The method and apparatus disclosed herein is believed to be the first practical system detailed for the automatic selective pre-collation copying of either duplex or simplex document sheets onto pre-collated duplexed copy sheet sets utilizing conventional single imaging, development and transfer copier stations. There is disclosed herein a system whereby a copier may utilize the same automatic document recirculation and copy sheet handling systems to provide pre-collated copy sets in duplex/duplex, duplex/simplex, simplex/duplex~ and simplex/simplex copying modes, thus providi~g all possible pre-collation copying modes from document sheets.

Some examples o~ art relating to pre-collation document handling systems in which a document is withdrawn from the bottom of a document set stack for copying, imaged at an imaging station, and then returned to the top of the stack, i.e. the original documen~s are multiply recirculated to and from the stac~ of documents, include: U. S. Patents Re. 27,976, (originally U.S. 3,499,710,issued March 10, 1970j to L. W. Sahley; U. S. 3,536,320, issued October 27, 1970, to D. R. Derby; U. S. 3,552,739, issued January 5, 1971, to R. R. Roberts, et al.; U. S. 3,556,511, issued January 19, 1971, to A. Hcward, et al.; U. S. 3,888,579, issued June 10, 1975 to V. Rodek et al.; and U. S. 3,937,454, issued February 10, 1976, to R. H. Colwill. A recent precollation copying system of this type is shown in Belgium Patent No. 835,568 laid open May 13, 1976, and West German patent application No. 2,550,985 published May 26, 1976, and French application Publication No. 2,291,131, laid open November 12, 1976. A dlsclosure similar to the latter is in U. S. Defensive Publication T957,006 of April 5, 1977, based on application Serial No.
671,865, filed March 30, 1976, by M. G. Reid, et al.. The systems shown in these latter cited applications also disclose other eatures of interest to the present appli-cation.
U. S~ Patent 2,822,172 issued ~ebruary 4, 1958 to C. R. Mayo et al. discloses a pre-collation copier with a vacuum drum holding and movinq the documents for imaging, It is known to multiple recyclingly copy the same side of a single individual document in a non-pxecollation copying system wherein the recycling path length may be ~ ~t~j4 changed to accommodate different sizes of documents, as shown in U. S. Patent 3,409,366, issued November 5, 1968, to W. J. Hanson, et al.. There a movable deflector ~inger in the document path selects between the two partially different document circulation paths.
rrhe general concept of imaglng a document while it is on a vacuum or frictional su~face drum, which drum also serves to invert the document for subsequently copying the second side thereof, i.e., as part o~ a duplex document copying system, is disclosed, for example, in the above-cited U. S. Patent 3,844,654, issued October 29, 1974, to J. Guenther. ~ote there drum 44, described in column 4.
Also noted in this regard are U. S. Patents 3,227,444, issued ~anuary 4, 1966, to ~. F. Egan; and 3,506,347, issued April 14, 1970, to C. F. Carlson (note Fig. 4).
Other examples of non-pre-collation copying systems with roller or other inverting systems i~ a document path ~or inverting duplex documents so that the opposite sides thereof may be imaged are shown in IBM
~echnical Disclosure Bulle~ins Vol. 14, No. 5, October 1971, p. 1547; and Vol. 19, ~o. 12, May 1977, p. 4496~ Another is U. S. Patent 3,862,802 issued January 28, 1975, to H. R. Till.
Of ~articular interest, as disclosing a means for selectively inverting or not inverting a document in a copying path, for copying one side of a document on one pass and the other side of that document on the next pass, is the system shcwn particularly in Fig. 6 and described at Columns 5 - 6 in U. S. Patent No. 4,040,616, issued August 9, 1977, S. G. Clarkson et al..

~ n oxample of a copier control system and logic circuitry in which the systems disclosed herein may be incorporated is described in U. S. Patent No. 3,936,182, issued February 3, 1976, to Sikander Sheikh~ While integral software incorporation into the copier's general logic circuitry and software, as in that patent, of the unctions and logic defined herein is preferred, the functions and systems disclosed herein m~y be conventionally incorporated into a copier utilizing any other suitable or known soft-ware or hard wired logic system or microprocessor or known cam-bank switch controllers for copiers. The control of the exemplarly systems disclosed herein may be accomplished by activating known electxical selonoid control sheet deflector fingers and drive motors or their clutches in the indicated sequences and does not require unconventional sheet handling har*ware or controls. Conventional sheet path position and jam sensor~switches may be utilized.
By way of background as to details of particular sheet handling apparatus disclosed herein, an example of a stac~ing tray with a bottom retard sheet feeder and a normal force applicator therefor is disclosed in U. S.
Patent 4,014,537, issued March 29, 1977, to K. K. Stange.
Bottom air flotation (which to a certain extent will affect the normal force re~uirements) i8 also disclosed there. The ~se of a foraminous impact or bounce pad for reversing the direction of motion of a sheet in a duplexing system is shown in U. S. Patent 3,856,295, issued December 24, 1974 to John H. Looney. I~ regard to the use of a con-tinuously rotating jogging or stacking member to compile sheets in a stack against a registration edge there is noted b~ way of example a U. S. Patent 3,709,595, issued January 9, 1973, to L. H. Turner, et al..
According to one aspect of this invention there is provided in an automatic pre-collation copyiny system for pre-collation recirculating copying of a set of duplex original documents, from a document storage means, at a docu-ment imaging means of a copier for copying the documentsonto copy sheets to form pre-collated copy sets, wherein said copier has at least one copy sheet supply means and a separate copy sheet intermediate storage means and a copy sheet output means, and wherein said copier has an image transfer station for transferring images of the documents onto one side of copy sheets fed from either said copy sheet supply means or said copy sheet intermediate storage means, the improvement comprising: duplex document recirculation means for multiply circulating said set of duplex documents in a recirculation path from said document storage means to said document imaging means for copying all of one sides of said documents once in each circulation and for returning said documents back to said same document storage means in each circulation, said duplex document recirculation means including inversion means for inverting said circulating documents in each circulation before they are returned to said document storage 'means relative to their initial orientation so that on alternate circulations of said documents alternate sides of said documents are copied by said document imaging means, and duplex copy sheet handling means for feeding all of the copies, made on one of the alternate circulations of the duplex documents, from said copy sheet supply means through said transfer station and into said copy sheet intermediate storage means, and for feeding all of the copies, made on the other of the alternate circulations of the duplex docu-ments, from said copy sheet intermediate storage meansthrough the transfer station again, inverted, and to said copy sheet output means, so that pre-collated duplex copy sets are produced at said copy sheet output means on alter-nate circulations of said duplex documents by said duplex document recirculation means; means for selectively feeding simplexed copy sheets from said copy sheet intermediate storage means directly to said copy sheet output means without passing through said transfer station on alternate said duplex document circulations, and means for feeding simplexed copy sheets made on the other alternate said docu-ment circulations from said transfer station to said copy sheet output means alternately and interleaved with copy sheets fed thereto from said intermediate storage means to form complete simplex copy sets at said output means from said duplex document set.
According to another aspect of this invention there is provided a method of making pre-collated duplex copy sets from a set of duplex documents by recirculating the set of duplex documents past an imaging station for individual copying by a number of circulations ralated to the desired number of copy sets, comprising: automatically circulating the duplex documents from a duplex document set to the imaging station and returning them to the document set inverted from their original orientation, so as to copy opposite sides of the duplex documents alternately on alternate circulations of the document set, and automatically copying one side of each duplex document in the order in which they are so circulated onto one side of corresponding copy sheets in one alternate circulation of said documents, - lOa -and copying the other slde o each duplex document on the other sides of the same copy sheets in the other alternate document circulation, to provide pre-collated duplex copy sets; further including the step~ of selectively alternatively - lOb -7~1.5~
providin~ pre-collated simple~ copy sets, b~ copying the duplex docume,nts in each circulation individually onto different sets of individual simplexed copy sheets, feeding According to another aspect of this invention there is provided a method of producing pre-collated simplex (one sided) copy sheet sets at the output of a copier from duplex (two-sided) original document sheets ~-hich are recirculated to the imaging station of the copier comprising the steps of:
copying only the first sides o~ said duplex document sheets in a first copying circulation thereof onto one side of copy sheets as simplex copy sheets, temporarily storing in said copier said simplex copy sheets made on said first copying circulation of said duplex documents as an intermediate buffer set, copying the opposite sides of said duplex documents onto additional simplex copy sheets in a second copying circu-lation and feeding said additional simplex copy sheets as they are made to the copier output alternately and interleaved with copy sheets fed from said buffer set to produce a com-plete precollated simplex copy sheet set from said duplexdocument sheets, and alternately repeating the above first a~d second copying recirculation steps to form plural, precollated simplex copy sheet sets.
Exemplary embodiments ol the present invention are shown and described hereinbelow incorporated into an otherwise conventional exemplary xerographic apparatus and process. However, it is not limited thereto. The xerographic apparatus and process itself need not be described herein since various known patents, texts and -- lOc --commercial apparatus are available to provide ~urther details thereof to -those skilled in -the art, including patents clted above. For example, the disclosed document handling system may be utilized wi.th various copier optics and copy sheet handling systems and processing sys-tems in addition to those disclosed herein.

- lOd -5~

~ 5.~ rl9LL55~TME DR~WINGS
Further objects, features, and advantages of the present invention pertain to the particular apparatus and steps whereby the above-noted aspects o~ the invention are attained. Accordingly, the invention will be better understood by reference to the following description, and to khe drawings forming a part thereof, which are approxi-mately to scale, wherein:
~ ~ig. 1 is à cross-sectional side view of an exem-plary automatic duplex or simplex document handling system in accordance with the present invention;
Fig. 2 is a partial perspective view of the integral stack normal force applicator and sheet jogger unit of the document handling system of Fig. l;
Fig. 3 is a view similar to Fig. 1 of an alternative embodiment of the document handling system of Fig. l; and Fig. 4 is a cross-sectional, partly schematic, view of an exemplary copier with a simplex or duplex copy sheet handling system in accordance with the present invention, on which the document handling system of Figs.
1 and 2 is mounted.

DETAI~ED DESCRIPTION OF TME PREFERRED E~ODIMENTS

Figs. 1, 2, and 4 illustrate one example of the present invention, and Fig. 3 shows an alternative example.
However, it will be appreciated that the invention may have many other different orientations and structures, and different combinations with different exemplary xerosraphic or other copying systems and optics systems.

, Referring ~irst to Fig. 1, there is shown an exemplary simplex/duplex recirculating document handler (RDEl) 20 mounted to a xerographi.c copier 10 for sequen-tial pre-collation imaging of ei.ther simplex or duplex documents automa~ically onto the photoreceptor 12 o~ the copier 10. Any desired number of document set recircula-tions may be made automatically, thereby allowing any desired number of pre-collated copy sets to be copied therefrom. The RDH 20 multiply recirculates individ~al documents 22 from a set o documents in a document storage area 24 to an imaging station 26 and back. During each individual circulation o~ a set of documents, a recirculat-ing document hand].ing system moves the documents individ-uall~ in a selected recirculating serial path from the document storage area 24 to and througll a document imag-ing area for copying each document once, and then returns them to the same document storage area.
Describing the various sub-systems o~ the RDH 20 of Fig. 1 in the order in which a document is recirculated in its circulation path, the document storage area 24 here comprises a generally conventional sheet stack holder or tray 28 adapted to retain and align the stack of document sheets thereon. As also shown in Fig. 2, there is a sheet or stack aligning front stack stop 30 adjacent the front end of the tray 28.
- ~ An intermittently operable individual bottom sheet separator and feeder 32 is provided to feed indi~i-dual slleets on demand from the bottom of the stack of sheets placed ln the tray ~8. The feeder 32 feeds out ::
.
, individual sheets in a single sheet feeding direction past the front stacX stop 30 from the ront end o~ the stack holder or tray 28. As sho~n, this bottom sheet feeding may be assisted ~y partial air flotation of the bottom o~ the stack by a blower and mani~old supply-ing air through apertures in the bottom of the ~ray 28.
Examples o~ such a bottom sheet feeding and air flota-tion system are disclosed in U. S. Patent 4,014,537, issued March 29, 1977, to K. K. Stanye, and the re~er-ences citéd ~herein. Also disclosed therein are normal force applicators pressing down on the top of the stack of sheets over the bottom ~eeder.
The exemplary bottom feeder 32 here similarly has a sheet feed belt 33 which extends under an aper-tured area of the tray 28 to engage the bottom surface of the bottom-most sheet therein and to puil sheets forward past the front stack stop 30 into a nip with a retard pad 34 which engages the upper surface of the sheets to pxovide sheet separation and allow only one sheet at a time to be fed from ~he tray 28.
In the RD~ 20, the docu~ents, whether simplex or duplex, may be loaded into the tray 2~ face do~n in their nonnal collated (forward serialj order. That is, the original doc~nent sheets do not have to be manually rearranged ir. reverse order by the operator. Nor, in ~he case of duplex docwnents, do copies need to be made of the second sides and inter-mixed with the original documents to ~orm a psudo-simplex document set. Further-more, as will be further described herein, at the end of the copying run the documents are automatically restored 7~

to their colla-ted condition in all cases so that they may be removed in collated order ater copying ~rom the tray 28. The RDM unit 20 lc; hinged to open along its duplex document path ~described hereinbelow) to fully expose the tray 28 for loading and unloading a set o~ documents therein and fol- jam clearance.
After passing through the separating throat ~ormed between the feed belt 33 and the retard pad 34, the lead edge of each individual document 22 here immediately enters a conventional registration system for aligning and registering for copying the front edge o~ the document. Here this comprises a registration gate 36 with sto~ fingers against which the lead edge of the sheet is buckled. Tha registration gate 36 is conventionally rotated out of the document path automa-tically at the appropriate time, controlled by the copier 10 condition, at which it is desired to feed the sheet downstream into the imaging-station 26.
In the embodiment of Fig. 1, the imaging stabion 26, which is immediately do~nstream of the registration gate 36, is of the moving docu~ent slit scanning exposure type. That is, the document is moved past a narrow scanning aperture 38 at a constant velocity synchronized with the velocity of the photoreceptor 12.
At the scanning slit 38 here, the document is uniformly held against, and driven by a vacuum cylinder 40. Only a bottom sector of the vacuum cylinder 40,is utilized for the imaging station 26. This may be accomplished, as shown here, by a "V"-shaped manifold 42 inside the vacuum cylinder ~0 which con~ines the applied vacuum to only that minor area o~ the cylindex 40 to insure that vacuurn adhesion and driviny of the documen~ is occurring only in that area. The manifold 42 is shown here supplied with a vacuum from a conven~ional blower 44.
Just as the leadin~ edge of the original docu-ment 22 enters the imaging station 26, at the beglnning of the vacuum segrnent area of the vacuum cylinaer 40, as shown, it is pressed against that vacuum segment of the vacuum xoller by a feed roller Sl. (This may, of course, be a series of spaced rollers on a cornmon shaft).
This roller 51 n.ips the docurnent into positive engage-ment with the vacuum cylinder 40 at this region.
~ he scanning slit 38 here may additionally include, as shown, a transparent platen or window 46 through which the document is sequentially imaged as it is transported on the vacuum cylinder 40. The illumination of the document is by a conventional fluorescent or other illumination lamp 48 with a light emitting area facing the window 46. This illumination is increased, and docurnent edge shadow effects reduced, by a thin vertical fresnel (mult,i-faceted) mirror 50 at the opposite side of the imaging station 26 from the lamp 48. The angles of the facets of the fresnel mirror 50 are individually di~ferently aligned to aI1 reflect light Erom the lamp 48 into the scanning slit 38. The image~from the illurninated document passes between the larnp 48 and mirror SO, and through an .

appropriate rnirror system, onto the photoreceptor 12.
Here this includ~s a mirror 55 pivoted into the optical path of a Xerox Corporation "4000" or other copier 50 as to utilize the same lens and most of the other existing optical elements, which are shown, for example, in U. S. Patent 3,775,008. However, the lens here is held stationary in this mode, and the mirror 55 blocks the normal image path from the copier platen. (With an over-platen RDH unit as in Fig. 3 or otherwise th1s would not be needed). When the mirror 55 is pivoted to its dashed position, conventional manual copying may be done on the copier platen. Variàble magnification could be provided by repositioning the lens and mirror and changing the speed o~ the vacuum cylinder 40.
The vacuum cylinder 40 and its associated com-ponents here provide several functions. It provides the support and background for the document imaging, it provides the driving of the document synchronized to the photoreceptor speed, and it also provides a first document inversion system in the document recirculation path. As will be further explained herein, the recirculation path for simplex documents here is an endless uni-directional eccentric loop with two document turnarounds and inver~ers in the path, while the recirculation path for duplex documents has only one document turnaround and inverter here. The vacuum cylinder 40 and its associated components here comprise the first one of these two document turnarounds and inverters, and is a part of both the simplex and duplex paths.

- 16 ~
, ~ ~'7~t~

To insure that ~he vacuum cyli~der 40 is driven smoot:hly and precisely at the synchronized photoreceptor speed, to prevent image skipplng or bluring, a separate belt 53 drive system directly from the photoreceptor drive is provided for the cylinder 40, independently o~ the drives o~ the regis-tration system and the other document transports o~
the RDH 20. This prevents intermittent torque varia-tions or vibrations ~rom these other components from affecting the movemenk of the cylinder 40 and, therefore, the movement o~ the document being imaged~ Further7 the only positive engagement of the document in the imaging station 26 is at and by this vacuum sector.
The RDH vacuum imaging roller 40 drive belt 53 here is brought rom the main copier drive shaft (low and centrally in the machine) up and over to the vacuum roller 40 in an L configuration. A cogged timing belt 53 is desirably used to prevent slip and maintain registration. However,~ an L belt configuration requires that the timing belt have at least one reverse or out-side bend around one idler roller as well as a forward or inside bend around another, adjacent, idler roller at the corner of the L, as shown. One-sided timing belts (with cogs or teeth on the inside only) do not take reverse bends well. This problem is avoided by using a commercially available two-sided timing belt 53 with cogs on both sides.

The documen~ is maintained in its desired path downstream ~rom the imaging station 26 and turned over (inverted) by means o~ a paper guide S2 con-tinuously spaced around the outside half of the cylinder 40. The guide 52 may contain idler rollers, but they do not nip the document against the roller 40 in this embodiment. Further, all of the downstream roller nips, including those in the registration gate 36, may be opened before the ~maging of the document begins. Thus, no substantial upstream or downstream frictional drag ~orces are acting on the document as it passes through the imaging stàtion, to insure that the document moves at precisely the same speed as the cylinder 40, i.e., without any slippage therebetween, in the Lmaging area.
A~ter each incremental portion of the document passes the exposure slit 38 and the corresponding end of the vacuum segment o~ the vacuum cylinder 40, there is no longer any vacuum acting on that se~ment of the document sheet. ~hus, the only force driving the document forward continuously to the subse~uent document transports beyond the vacuum cylinder 40 is the positive engagement between the document and the vacuum cylinder 40 in the vacuum segment, particu~arly at the nip with the feed roller 51. At no time is vacuum ever applied to any portion of the cylinder 40 other than the Iess than 90 fixed bottom sector area.
Further, no air pressure is required to strip the sheets at the top of the cylinder 40.

. . .

, In thc system disclosed hereinabove, the document recirculation path is th~ same for both simplex and duplex documents at: all times up to the exit o~ the lead edge of the document from the upper sur~ace of the vacuum cylinder and ~irst inverting roller 40. At that point in this embodiment there is a critical juncture from which two separate return paths are provided to the document storage area 24. There is a first (simplex) return path pro-vided by a simplex belt transport 54 over to and around a second inverting roller or cylinder 56 from which documents are ejected into the tray 28, above and at the rear end o~ that tray. Alternatively, there is a separate second (duplex) document recirculation return path provided by a second (duplex) document transport 58 directly from the ~irst inverting roller 40 into the front end of the tray 28.
The selection of one o~ these two pa~hs versus the other is made here by a duplex/simplex switching system including a sheet lead edge de~lector finger 60 which pivots between the illustrated solid line (simplex) position and the illustrated dashed line (duplex) position. In the ~irst or simplex position all documents exiting the vacuum cylinder 40 are directed by the finger 60 into the first or simplex transport 54, while in the second or duplex position documents are directed downstream into only the second or duplex transport 58.
. It may be seen that by selecting between these two positions o~ the deflector ~inger 60 that the simplex transport 54 and its integral second inverting roller 56 may he readily automatically switched in or out of the document recirculation path, in coordination with the recirculation of a document set, to thereby selectively provide in each circulation either a single inversion of each document (by-passing the second inverter) or two inversions in seri.es of each document. The switch-ing of the ~inger 60 may be accomplished by a conventional solenoid electrically connected to the machine logic controller.
With the single inversion tthe duplex path) selected, a document which is initially ~ace down in the tray 28 will be returned face up, i.e., turned over, to the same tray 28 after it i5 imaged on each circulation. Thus, by the end o~ the circulation, all the documents in the circulated set will all have been already inverted during the copying circulation itsel. With the circulation path with both inversions (the simplex path) selected, each document is returned to the tray 28 in the same orientation it had before being circulated, i.e., without being inverted.
The respective inverting rollers 40 and 56 provide these document inversions, and also a turnaround or change in document movement direction, by each rotating the documents approximately one-half way around the outsides of each roller. Simple uni-directional and basically linear ~planar) document transports 54 and 58 may therefor be utilized with this RDH configuration as further des-cribed herein.
When the recirculated documents are returned to the document storage area in their original orientation, the same sides of the documents will be copied in th~

subse~uent recirculations o~ the document set. ~owever, by returning the recirculated documents to the document s~orage area in inverted orientation, as further des-cribed herein, the opposite sides o duplex documents ~ay be immediately copied in the subsequent recirculation of the document set. That is, the even numbered pages of a duplex document may be copied on one circulation, the odd numbered pages copied on the next circulation, the even numbered pages copied on the next circulation, then the odd numbered pages copied again on the next circulation, etc., etc..
It may be seen that the present system is desirably compact. The entire document storage area 24 and both transports 54 and 58 and the document registration and Lmaging stations are all located interna~ly between the two rollers 40 and 56 providing the two document inverting areas. No external inverting system or path is required.
Both the simplex and duplex recircu~ation paths are con-tinuous and uni-directional, i.e., the movement o~ the circulated documents does not have to be stopped or reversed at any time, even during the document inversions except for registration. That is highly desirable, since it reduces the potential for jams and reduces the document path lengths With the disclosed system the duplex switching is accomplished solely by appropriate actuation o~ a simple deflector finger or fingers 60 directly adjacent the first inverting roller 40, closely downstream from the imaging station 26. The duplex switching means 60 here is positioned directly in the recirculation path , ~ '7~ ~ ~

intermediately of the first and second document invers~on systems, and operates to selectively by-pass the second doc~nent inversion system. At the switch 60 both return pa~hs are in the same dixec-tion, and nearly parallel, only slightly angularly diverging approximately 20 for the duplex path.
Thus, the document does not have to be sharply arcuately deformed to enter either path at the path selection area.
Both document recirculation return paths are s~ort and direct and may be continuously convention-ally driven. A sLmple and direct, single inversion, duplexing system is provided. The initial portion of the circulation path is shared in common by both the simplex and duplex paths through the critical feed-out, operation, registration, imaying, and initial inversion areas, ut~lizing the same space and the same components.
The two document recirculation paths from the imaging station back to the document storage area are different and distinct from each other and from the common document recirculation path from the docu-ment storage area to tha imaging station 26. Thus, one document may be being fed from the tray 28 to the imaging station while another document (previously imaged) is being fed from the imaging station back into the tray 28 through either the simplex or duplex document paths. Further, it may be seen that all the documents are entered directly and linearly from the tray 28 into ~he imaging station 26 in the document recirculation path prior to any inversion of the documents by either of the document inverting systems.
Considering now in further detail the ~irst or simplex document belt transport 54, this comprises here a single opposing and partially overlapping pair of narrow, centrally located, endless belts 62 and 63.
The two belts 62 and 63 transport a document linearly therebetween from the deflector finger 60 at the vacuum cylinder 40 to and around the second inverting roller 56. Documents only enter the transport 54 when the deflector finger 60 is in its simplex (solid line) position. Thus, both belts 62 and 63 may be driven continuously by driving the roller 56, around which they both half-wrap.
The upper transporting flights of both belts 62 and 63 extend horizontally between the upper tangents of the rollers 40 and 56, passing well over (above) the document tray 28. The belt 63 is wrapped at its upstream end around a small roller 64 in that path.
The belt 63 then extends linearly to centrally wrap around the outside half of the circumference of the much larger second inverting roller 56. The non-, . , transportiny flight of the belt 63 then returns tothe-roller 64 directly from the bottom of that roller~
`56.
The mating transport belt G2 is correspond-ingly mounted at its upstream end at a small roller 66 closely adjacent, and overlying, the upper surface of th~ vacu~ cylinder 40. It then extends to, engages, and travels in overlapping relationship with, the belt 63 from roller 64 to the second inverting roller 56. There, the belt 62 is wrapped directly over~ying the belt 63.
This forms a positive, sandwiching, central retention o~
any document between the belts 62 and 63 around the second inverting roller 56. Curved baffles 71 guide outside edges of the documents (especially if dog-earred) around the rollex 56. Since both belts engage only the central area of the documents, skew is not induced in the documents by the transport 54. The document is engaged between the two belts 62 and 63 from the roller 64 position to the bottom tangent of the second inverting roller 56. There the first belt 62 is sharply stripped away ~rom the second belt 63 by a small supporting roller 68 to release the documents. ~he outer (non~transporting) flight of the first belt 62 is then returned to the roller 66 via the roller 68 and two small rollers 69 and 70 spaced from the second inverting roller 56.
At the document ejecting point between the rollers 68 and 56 the document is driven in over the top of the stack of documents in the tray 28 from above the rear end thereof but in the same direction of movement as the sheets being fed out by the bottom feeder 32, as shown by the movement arrow there. Thus, the sheets are driven in the direction of the front stack stop 30 in this simpIex (dual inversion) return path.

. - 24 -. . .

Considering now the second or duplex document transport 5~, this duplex document return path is utilized only when the deflector finger 60 i9 raised to its dashed line position. ~n this single inver-sion mode path the documents are transported directly from the top o~ the irst inverting roller 40 onto the tray 28. They are driven in from the fronk side of the tray in a direction opposite from the direction in which documents are ~ed out from the bottom thereof, as shown by the movement arrow there. Note that this is at the opposite end o the tray and the opposite move-ment direction from the simplex path tray entry des-cribed above. This transport 58 here is provided by low friction opposing metal sheet guide or baf1e sur-faces 72 and 74 which are parallel and closely spaced to define the duplex return path, and by continuously driven feed rollers 76 and 78 spaced along that path.
The upper bafle 72 extends up to and transitions smoothly into the deflector finger 60. The bottom sheet baffle 74 extends from below the finger 60 and terminates substantially above the front stack stop 30, and, as shown, may be integral therewith, It may be seen that the overlying baffle 72 also extends down over the central portion of the tray 28 and then up to the second inverting roller 56, adjacent the ejection point of the first transport 54 there, so as to provide a final sheet guide or baffle for the first transport 54 as well. F~rther, an upper horizontal extension cf the baffle 72 here extends horizontally in the sisnplex path from the ~inger 60 to support the sides o~ sheets bein~ onl~ cen~rally held between the belts 62 and 63.
Positive driving of a clocument in the duplex transport path 58 is provided here by two pairs of opposing small diameter foam rollers 76 and i8, which are nipped at openings along the baffle 74 to en ~aye documents directed hetween the two baffles 72 and 74 by the ~inger 60. The second pair of rollers 7a is positioned at the output or e jection area o this duplex transport 58.
If desired, by increasing the vacuum segment of the vacuum cylinder 40, it could be utilized for alternatively making multiple co~ies of a single document continuously held on the cylinder 40 as it rotates , i . e ., not entering either of the duplex or simplex transport paths until a fter a pre-set number of copies are made, rather than after one copy as in the system disclosed herein.
Copies are inserted and copied page 1 first, rather than last page first~ in the disclosed system for either simplex or duplex docoment copying, i. e., in forward serial order. Thus, job recovery in the event of document or copy sheet jams is simplified. The position of the particular docurnent being copied when the jam occurs and that copy page, relative to the rest o E the set can be counted from the beginning of the set, independent of the number of doc-unents in the set. The number of documents copied before the jam will be registered iD a conventional counter in the copier logic.

L S ~

Referring now to Fig. 3, there is disclosed therein a second, alternative,embodiment and example o~
the RDH unit. This RDH 200 is generally similar to the RDH 20 of Fig. 1, and accordingly only its principal distinctions will be described here. This RDH 200 is designed to operate mounted over an existing platen 202 imaging station of a copier to utilize the existing platen scanning optics, As an example of such a platen scan~ing optics system there is shown here an optics system o the type utilized in the Xerox Corporation "3100" copier. However, it will be appreciated that any other stationary document scanning or full frame illumination system may be utilized instead. Here there is shown a platen scanning illumination lamp 204. Thè
image of the document is simultaneously scanned by a half-rate mirror system 206, including a split lens/
mirror unit 207, to provide a flowing ~age o~ the document on the photoreceptor 208, In this particular example of Fig. 3~of a full document size platen RDH unit 200, the transport and in-focus retaining of the document over the imaging station (platen 202) is provided by a wide light-re~lecting document belt 210 closely uniformly held over the platen. The registration of the document on the platen 202 may be conventionally provided by a solenoid operated registration gate 214 at the down-stream edge of the platen 202, connected to the machine controller.
, LS~

The belt ~10 i9 mounted here between a large roller 212 (~orresponding generally to the roll~r 40 of Fig. 1) at the downstream or output side of the platen 202 and a smallar roller 213 at the input side of the platen. ~owever, here the rolle~ 212~need not ~e a vacuum roller. Driving of the document around the roller 212 to provide the initial documenk inver-sion is provided by nipping the document agains~ the outer surface o~ the document belt 10 on ~he outer side of the roller 212 by a plurality of rollers in a sheet guide 216 there. It may be seen that except for being slightly longer, the simplèx and duplex document return paths, and ~ocument transports thereor, may be very ~imilar to those previously described for the RDH 20 o Fig. 1. However, here the duplex return path utilizes the upper flight o-the belt 210 instead o~
baffles for most of that return to the document tray from the first inver~ing roller 212.
.. . .... .. .. . . .

R~ferring particularly to Fig. 2, there will now be described the copier sheet feeder disclosed herein providing an integral normal force applicator and jogger 80 for simply and automatically stacking and allgning sheets as they are inserted into the top of the sheet stack holder and simultaneously providing an appropriate normal force on the stack against the bottom sheet feeder which is feeding individual sheets from the bottom of the same stack. This sheet feeder unit is also shown in side views in Figs. 1 and 3, incorporated in those circulating document handler embodiments. A slightly different embodiment 122 of this same jogger/normal force concep~
is incorporated in the duplex copy sheet tray 116 in Fig. 4. However, the following description will be with particular reference to Fig. 2 which shows this system 80 in a partially broken-away perspective view. Fig. 2 also shows portions of the previously described document tray 28, front stack stop 30, and the bottom feeder 32 (including the feed belt 33 and retard pad 34) for separating and ~eeding out the bottom-most individual sheet from the bottom of the stack of documents 22.
This integral normal force applicator and jogger unit 80 includes a jogging roller system rotatably mounted adjacent the front stack stop 30 to engage the top of the stack of sheets in the sheet stack holder.
This is provided here by a spaced plurality of soft, highly foraminous, polyurethane foam wheels or rollers 82 secured to a common shaft 84. The shaft 84 is con-tinuously rotated from one end, as shown, in a direction S~

indicated by the arrow of. rotation, so that the wheels 82 engage individual sheets fed onto the top of the stack of sheets and move them toward the front stack stop 30.
The shat 84 is itself mounted for vertical movement relative to the tray 28 ~to accommodate differ-ences in the height of the stacX of sheets therein) by elongated linear pivotal arms 86 and 87, respectively connectin~. to the opposite ends o the shaft 84 outside o~ the opposite sides of the tray 28. The arms 86 and 87 are pivotally mounted on a fixed mounting shaft or axis 88 substantially spaced from the shat 84 along the arms. The shaft 88 is positioned centrally and spaced above the tray 28. The same pivot a~is 88, may, of course, be provided by separate pivotal connections at each side for each arm, eliminating a central shaft there.
. The arms 86 and 87 extend linearly beyond the - other side of the mounting shaft 88 from the shaft 84 to a counterbalance or counterweight 90. The downward force of the counterweight 90 acts on lever arms provided by the length of arms 86 and 87 from the mounting shat 88 to the counterweight gO. This provides a corresponding lifting or counterbalancing force through the other lever arms provided by the length of arms 86 and 87 between the pivot axis 88 and the shaft 84. This counterbalances a desired portion of the weight of the entire normal ~orce unit comprisin~ the wheels 82, shaft 84, and associated components. If desired, this counterbalancing may be made ad~ustable by any suitable means, such as the illustrated adjustable mounting slots for the mountin~

..
.

position o~ ~he counterweight ~0 on the arms 86 and 87.
Although not essential, as shown in Fig, 2 the front stack stop 30 may be a~ertured at the locations of the wh2els 82 to allow the fronts of the wheels 82 to extend beyond the front stack st:op 30. ~his allows the nip between the wheels 82 and the stack of shee~s to be directly adjacent the ~ront stac:k stop; thereby overlying the bottom feeder 32 along a line directly across the entire front edge o~ the stack closely adjacent the retard nip between the feed belt 33 and the retard pad 34.
The above-described mounting and counterweighting of the integral normal force applicator and jogger unit 80 causes the set of jogging rollers 82 to be uniformly pressed against the top of a stack of sheets in the sheet stack holder with suf~icient force to pxovide a normal force for the bottom sheet feeding system 32 regardless of the number or weight of sheets in the stackO It also provides a sufficient engagement force between the wheels 82 and the top sheet to drive the top sheet against the front stack stop. However, this normal force is suffi--ciently low to allow the wheels 82 to continuously slip once the top sheet is abutted against the stack stop, without buckling the sheet or driving the top sheet beyond the front stack stop, or abrading the sheet.
It is important to note that the unit 80, particularly the wheels 82, are not lifted as each sheet enters the tray, nor is the bottom feeding interrupted, as would be required with various conventional holddown normal force applicators.

The specific normal ~orce may vary, depend-ing on ~he number, size, and material o the wheels 82, providing the descri~ed ~unctional charact~ris-tics of their action on the sheets are satis~ied.
The use of multiple foraminous wheels for document or other sheet handling per se is taught in art cited in the introduction and elsewhere.
~ t will be appreciated that other weighting or spring biasing means may be provided to compress or impose the desired continuous but light normal or holddown force on the stack through the wheels 82.
This normal force desirably allows a non-vacuum bottom sheet feeder to ~e used reliably even for small stacks of only a few sheets.
The jogging wheels 82 are sufflciently soft and foraminous to deformably lightly engage the sheet without marking or damaging that sheet with the above-described pre-set light normal pressure even with con-tinuous slippage, and thus may be desir~bly ~ept turning continuously during the operation of the copier to continuously maintain a forward force against the stack and to continuously accept and feed in individual top sheets, independently of the operation of, and simul-taneously with, the operation of the bottom feeder 32.
Thus, this jog~er unit automatically positions all of ,the sheets at the forward edge of the tray and provides for continuous top input and bottom output.

.p~

~ he continuously rotating foraminous wheels 82 have a rough surface and continuously downwardly moving rear surfaces, i.e., at their sides opposite from the front stack stop. The wheels 82 ha~e equal diameters so that they may all simultaneously engage the front edge of the sheet. Thus, the edge of any sheet engaging these wheels 82 is pulled down onto the stack by the wheels, an then pulled forward uilder the wheels. ~hus, each top sheet is pulled down, captured in the wheel nips, and slid forward on the top of the stack under the wheels into alignment with the fron~ stack stop.
` If the top sheet is initially skewed, so that one side of its lead edge engages the stack stop before the other, the wheels 82 overlying that side of the shee~ will begin to slip while the other wheels 82 will continue to feed the other side of the sheet forward into full alignment with the front stack stop. To this end, the wheels are desirably spaced s~ that both sides of the shee.t are engaged by at least one wheel 82, as shown.
The wheels 82 are relati~ely small in diameter~
e.g., less than approximately 2 centimeters, particularly in relation to the much greater distance between wheels 82 and the mounting shaft 88. There is a large and totally unobstructed opening in this area, much wider than the maximum width of a sheet to be placed in the tray 28, and much wider than the tray 28 it5elf. This opening is specifically adapted ~or the unobstructed passage of sheets over the front stack stop 30 and over the entire jogger wheel unit onto the stack of sheets in the tray 28. Thus, as described above in connection with the operation of the duplex trans-port path 58 in Fig. 1, sheets may be fed into the tray 28 from the front thereo in a direction opposite the sheet feeding direction while sheets are being simultaneously fed out rom the bottom of the stack in the same tray at the same time. The mounting of the wheels 82 by the widely spaced arms 86 and 87, and their being driven from an outside end adjacent one of - those arms, (as opposed to the shàft 84 being conven-tionally centrally mounted and driven) allows this area over the wheels 84 and shaft 82 to be completely unobstructed at all times for such front loading.
In the embodiment of Fig. 1 an additional rear nudger or jogger 92 is shown at the rear end of the sheet stack holder opposite from the ~ogging roller unit 80 for engaging and urging any sheets ed there-against toward the jogging roller wheels 82. This rear jogger ~2 does not drive the sheets against the front stack stop 30 as with a conventional rear jogger, since that is accomplished here by the continuously rotating wheels 82 once they er,gage the sheet. Where the tray is downwardly inclined towards the front stack stop, as in Fig. 4, the rear jogger is, desirably, eliminated.

Referring to Figs, 1 and 2, there is shown a ~urther feature of the copiqr sheet feeder system disclosed herein.
This is an inter-relation of the bottom sheet ~eeder 32 with the integral normal force applicator and jogger unit 80 described above. Specifically, as shown in Fig, 1, the portion of the frictional document feed belt 33 extending under the bottom of the stac~ of documents 22 (in an aperture in the bottom of the tray 28) is belt by its supporting rollers there so that the feed belt 33 is maintained slightly (e.g., approximately .3 centimeter) above the plane o~ the tray 28, but generally planar and parallel the tray bottom. As shown in Fig. 2~ this sheet pull-out portion of the belk 33 extends between the two center-most jogger/normal force rollers 82.
That is, two of these rollers 82 are spaced closely adjacent opposite sides or edges of the raised portion o~ tha belt 33, and no roller 82 overlies the feed belt 33. This causes a slight upward buckling of the forward central area of the stack of sheets in the tray 28 over the belt 33. The ~oam rolls 82 pressing down at opposite sides thereof confine this buckle over the belt 33 to maximize the normal ~orce between the sharp edges of the belt 33 and the bottom sheet and minimize the normal force between the central area of the belt 33 and the bottom-most sheet. That is, the normal force applied by the rollers 82 is concentrated at the edges of the feed belt 33 to increase its ~eeding reliability, whilé the buc~ling of the bottom sheet over the central portion of the feed belt 33 reduces the tendency for image smearing image due to slippage between the feed belt and the sheet.

R~erring now to ~ig. 4, there is shown therein an exemplary copier 10 in accordance with the present invention. This view of Fiy. 4 is partly schematic.
to particularly emphasize the copy sheet path of the copier 10, to which the following description will be particularly directed.
Referring fi.rst, however, to the image input to the copier 10, there is shown in Fig. 4 the imaging station 26 of the simplex/duplex recirculating document handling unit 20 previously described with reference to .Figs. 1 and 2. Also shown is the optics. system described thexe for imaging each document onto the photoreceptor 12.
The photoreceptor 12 here has the normal xerographic imaging, development, transfer, stripping, and cleaning stations acting thereon to develop the document image on the photoreceptor 12 with fusable toner material and to - transfer that image to one side of a copy sheet at a trans~er station 112. That transferred page image is then fused to the sheet at the fusing station 114.
In the copier 10, clean (unimaged) copy sheets may be fed into the transfer station 112 from either of two copy sheet trays 106 or 107. After transfer and fusing has been accomplished, the copy paper output path arcuately bends as shown to transport the.copy sheets to which an image has just been fused on one side out toward an exit area.
The above-described features of the copier~10 are generally similar to that of the Xerox Corporation "4000" and "4500" copier and need not be ~urther .

descrihcd in detai]. herein. Ho~Jever, in the copie~
10, as the ~used copy slleet is being transported out toward its normal exit area it passes through 5iyni ~icantly different structural and func-tional features.
First, each copy sheet passes through a gate comprising here a duplex selector ~inger 118. Depending on the position of this inger or gate, the copy sheet will either be directly passed out throu~h a transport 126 or captured in a duplex buf~er s~orage tray 116. These structures are shown in simplified form here to clarify their operation, and it will be appreciated that other structures providing their function as described below may be substituted.
Assuming that the deflector finger 118 is posi-tioned by the controller 100 in its raised position illustrated here, the lead edge of each approaching copy sheet (on which a document page has just been copied on one side thereof) is deflected by the finger 118 down onto the top of the stack of sheets present in the duplex tray 116. As the lead edge of the copy sheet reaches the far or upstream end of the tray 116 it strikes a foam rubber or other suitable bounce pad or reverser 120. The resiliency of the pad 120 coupled with the downwardly inclined orientation of the tray 116 causes the copy sheet to then reverse its direction of movement.
h~hat was previously the trail edge of the sheet now has cleared the finger 118 and is now directed backwards against a set of ~ogger/normal force wheels 122 adjacent the front or downstream edge of the stacX 116.

These wheels 122 are similar in s~ructure and function to the integral normal force applicator and jogger unit 80 wheels 82 sPparately described herein in relation to Fig. 2, The wheels 122 here are desirably somewhat larger in diameter than the wheels 82 so as to insure capture and pulling down of the trail edge of the copy sheet even if it ~s still "floating" above the ,other sheets in the stack. The wheels 122 capture what was the trail edge o~ the entering copy sheet and stack it under the wheels in alignment with the front stack stop of the tray 116 at its downstream or forward edge.
, The tray 116, similar to the tray ?g of Fig. 1, has a bottom retard feeder 124 for feeding individual sheets from the bottom of the tray 116~ This may be separately or simultaneously with the feeding in and stacking of individual sheets on the top of the stack of sheets in the tray, As in the tray 28 of ~igs. 1 and 2, the copy sheets enter the top of the tray 116 in a direction opposite from that from which copy sheets are fed out of the bottom. The incoming sheets are fed in over the tops of~the jogger/normal force rollers 122 at the same front edge of the tray from which the sheets are fed out, rather than from the rear or upstream side of the tray.
It may be seen that due to the inversion in the copy sheet path from the transfer station 112 and fuser 114 to the tray llS, that the copy sheets are inverted :

by the time ~hey reach the tray 116. That is, the images just transferred to the copy sheets entering ~he tray 116 are all on the top side thereof, and not on the opposite or hottom side ~rom which they are fed by the feeder 124. Thus, the feeder 124 here can eed sheets from the clean side thereof dixectly into the ~eeding and registration path to the transfer station 112 for the transfer o the second (odd page) document images to the second, clean (previously uncopied) side of the copy sheets which were stored in the tray 116.
Considering now the operation o~ the copier 10 when the deflector fingers 118 are in their second, lowered position, illustrated by the dashed outline, this causes all of the copy sheets coming from the fuser 114 to ~e deflected into the transport 126. The transport 126 passes over the top of, and by-passes, the tray 116, in a closely ad~acent, compact, manner.
The copy she~ts being ed out by this over-tr~y transport 126 then enter an output inverter unit 128 which includes a further selector or deflector gate operated by the contxoller 100. There the copy sheets may selectively be either inverted and immediately ejected into an inverted output tray 130 or further transported into a finishing station 140 for automatic stapling or other appropriate finishing operations.
With re~erence to the copier 10 of Fig. 4, by way of example, there will now be described a method of automatically copying the images on both sides of recirculated duplex documents onto both sides of copy slleets to make any desired number of pre-collated duplex copy sets in an e~icient and continuous manner, First, as elsewhere further described here, only the even page sides of all the duplex documents in the duplex document set placed in the tray 28 are sequentially imaged at the imaging station 26 in the first document circulation. These sequential images of the even pages are copied onko a first side o a corresponding number of copy sheets sequentially fed from either of the (clean) copy sheet trays 106 and 107, at the transfer station 112. As all of these ~now simplexed? even numbered copy sheets exit the transfer station 112, they are all temporarily stored in a buffer storage area, provided here by the tray 116.
on ~his copying circulation of the even sides of the docu~ents none of the copies are exited to the output of the copier.
During all but the last copying circulation of the duplex documents all of them are inverted, so that at the end of every even side circulation all of the documents have been inverted and their odd sides are ready to be exposed and copied. Then, on the next circulation of all of the documents in the docu.~ent set, all o~ only the odd page sides of the documents are Lmaged. Those odd page images are all transferred to the opposite (previously unimaged) sides of copy sheets fed seguentially by the bottom feeder 124 only from the duplex tray 116. After the transfer and fusing of this second side image, these copy sheets, ~1. lL7~

which have now already been duplexed in the second circulation of the duplexed documents, are ali exited ~rom the copier to the output tray or finisher by the switching o~ the de~lector finger 118 prior to thi.s second document copying circulation. No copies are put into the tray 116 on any odd side exposed circula-tion of the documents. Thus, a completed duplex copy set is ejected from the copier on the second, and each subse~uent,odd side document circulation, and the duplex tray 116 is emptied and is ready to receive simplexed documents on the next (evenj document circula-tion.
Since all of the documents are again inverted during the second document circulation, upon the third aocument circulation only the even sides o~ the document set are copied once again onto a new set o~ copy sheets fed from the trays 106 or 107 to repeat the previously described operation. The above-described steps are repeated in the above sequence by the number of times corresponding to the desired number of copy sets to be made from the documents.
A single set of document even side copy sheets is the most that is stored in the duplex tray 116 at an~ time. The maximum number o~ these stored copy pages is equal to only the number of even document pages copied, independent of the number o~ copies made of the documents.

:1 ~. L'~

It will be noted that the operation and function of the deflector 118 and duplex tray 116 will vary, depending on the type o~ copying selected. By selecting appropriate copier external switches, in a ~nown manner, the controller 100 is directed to operate the paper path and paper feeder functions des-cribea above, or otherwise,automatically through conventional solenoid,clutch, cam or other drives.
For example, when it i5 désired to utilize the copier 10 to conventionally make simplex copies of simplexed documents, rather than duplex/duplex copying as des-cribed above, the deflector ~inger 118 is set to de1ect all copy sheets directly to the output area, and the tray 116 is not utilized. Conversely, when simplex documents are to be duplex copied onto duplex copy sheet sets, as further described hereinbelow~the operation of the sheet feeder 124 from tray 116 is alternated with the sheet feeder of tray 106 or 107, to alternate feeding of sLmplexed or blank copy sheets to the transfer station 112, and the deflector 118 is switched between each copy sheet to alternately~
deflect the simplexed copies into the tray 116 and the alternatively comple~ed duplex copies to the desired output.
Alternately, when the copier 10 and the RDH
20 is utilized for making simplex copies from duplex documents, this may be done different ways. one known way would be to make one set of copies o the otherwise hidden sides of the duplex documents, e.g., all the even sides,and interleave those copies with the other ~3 ~

documents to form in e~fect a pseudo-simplex document set which can then be copied as such. Another method would be to utilize the above-described automatic duplex document recirculation system in which a set o~ even page simplex copy pages would be made in one document circulation, a set of odd simplex copy pages would be made in the next doc~nent circulation, etc..
This, however, would then require interleaving of the odd and even simplex copy pages to form a completed simplex copy set from the duplex originals.
In the disclosed method of making duplex copy sets from duplex documents, it is desirable for the operator to be able to initially load the documents in the document handling unit in a normal pre-collated forwaxd serial numerical order. That is, the duplex documents may be loaded here face down into the tray 28 in their normal page 1, 3, 5, etc. order. (It will be appreciated that in an RDH in which the documents are inverted be~ore they are copied that the set may be initially inverted).
Yet, as otherwise described herein, it is advantageous to first copy the e~en pages and to store those even page copies in the buffer tray 116, and not odd page copie~s. This is accomplished here by first operating the RDH 20 for an initial single document circulation in which none o the documents are copied and in which no copy sheets are fed. This initial "blind" circula-tion o~ the documents reorients the documents in the tray 28 appropriately for the copying of the even pages first on the first actual copying circulation o~ the documents. Thus, the first copying circulation of the ;

even pages may then immediately preceed wi~hout rcquiring any operator intervention.
At the completion o~ the copying of the duplex documents onto the desired number of duplex copy sets, it will be appreciated that the document set could be additionally circulated in (another) final non~copying circulation to return them to their forward serial order collation, so that they may be removed by the operator in the desired order in which they were initially placed in the tray 28 by the operator.
However, it has been found that the same result can be achieved without requiring such a second non copying circulation. This is accomplished here during the last copying circulation of the document set by switchïng the deflector finger 60 in the RDH unit 20 to cause the duplex document set to follow the simplex transport 54 path back to the tray 28 on only this last circulation, xather than the duplex path utilized for all of the previous circulations. That is, the duple~ documents are not inverted in their last copying circulation. This automatically recollates the documents in forward serial order during the last copying run or circulation so that they may be removed from the tray 28 Lmmediately after the completion o~ copying in their desired order.
It should be noted that in the duplex document copying system disclosed herein that all the same sides of all the documents in the document set are all imaged in each circulation. That is, all odd sides are copied or all even sides are copied. No document sheetR with images on them are skipped (not copied) in their circulation on either duplex or simple~
document copying, except on the first circulation of duplex documents for duplex/duplex copying and on the first and last circulation of simplex documents for simplex/duplex copying as further described herein.
For all circulations, regaxdless of whether odd or even sides are being imaged, and for either duplex or simplex documents, the documents are imaged at the same, single, imag~.ng system and b~ the same, unchanged, optics system.
In the duplex/duplex copving system described herein, it is desirable to begin copying, i.e., the first copying circulation of the duplex documents, with the even pages, i.e., the even numbered sides of the duplex documents. One reason for copying the even document pages first is that in a duplex document set if there are an uneven number of pages the last duplex document sheet will actually be a simplex document.
For example, a five page duplex document set would normally have pages one and two on opposite sides of the first document sheet, pages three and four on opposite sides of the second document, but page five on only one side of the third document, with the other side of the third docwment being blank (i.e., no actual page six). By copying the even sides ~even pages) first, only pages two and four need to be copied, on only two copy sheets, in the first document circula- -tion, Thus, only two copy sheets need to be stored in the duplex bu~fer storage tray on the first document circulation. By the operator informing the copier (with switch settings) of the ~uneven) number o~
pages and the ~act that the documents are duplex documents, the copier can be automatically pre-set to skip (avoid copying) the last even page in each document circulation of the even sides. That is, in this example, the even side of the third document sheet, which would otherwise be page 6, is not copied, and no third copy sheet is fed to receive a blank page six image. Thus, the transfer, fusing, and feeding of a final blank unprinted copy sheet into the duplex tray is avoided in the circulation of the even page sides of the documents for copying.
on the next document circulation, wherein the odd document pages are copied, page 1 will be copied on the reverse side of the copy sheet on which page 2 was printed in the prior document circulation, by feeding that same çopy sheet from the duplex tray. Likewise, page 3 is printed on the back of the copy sheet on which page 4 had just previously been printed. However, the last odd page, page 5 in this example, can be automa~
tically printed on a~clean copy sheet fed from the copy sheet tray rather than from the duplex tray.
Thus, the final copy sheet of the copy set, on which page 5 is printed here, does not have to go through the transfer and fusing station twice, and never has to go in or out of the duplex tray. It may be seen that these same advalltages hold for all subsequent circula-tions tpre~collation copying set cycles).

As described in the above-cited Adamek~ et al.
~. s. Patent No. 4,116,558, duplex copies can aiso be provided here rapidly and e~ficiently in pre-collated output copy sets from a set of simpléx documents recirculated in serial order by a different method than that described above for duplex documents, In the first copying circulation of the simplex document set only the even-ordered (e.g,, pages 2, 4, 6, etc.) documents are copied (once) onto the first sides o~ the copy sheets, skipping (not copying) all the odd pages. Those copies are transported to the duplex buffer storage area. Then on the next, and all but the last, document circulations, individual copies are made,in order,of all the document pages, odd and even, but alternately copying the odd order documsnts on the reverse side of the previously simple~ed copies fed from the duplex buffer set while alternately copying the even ordered documents onto clean copy sheets fed from one of the,copy sheet trays, The finished duplexed copies made from the buffer set are transported to the output to accumulate as pre-collated duplex copy sets, while simplexed copies made from the even document pages are fed to the buffer tray to replace the copies being fed therefrom.
All of the document pages in the set are repeatedly individually copied in the latter manner in a number of document recirculations equal to one less than the total number of copy sets desired, Then, fox the last copy set, copies are made of only the odd ordered , documents onto the revers~ side~ o c~pies fed only from the duplex bufer tray.
As taught in the above~cited U. S. Patent No.
4,116,558 -to Adamek, et al. ~or simplex/duplex copy-ing it is desirable to copy only the even page numbered documents on the first copying run. As stated there, the odd numbered documents could ~e imaged on the first pass of the ADH instead. However, as stated there, to do so would require an extra pass of t:he last copy sheet through the transfer station without putting an image on the even side thereof in the cop~ing of an odd numbered document set, e.g., a set o~ 5 documents. Alternatively, if one did not make an extra pass, an inverter would have to be used to insure proper orientation of the last odd copy sheet. one pitch on the imaging member (photoreceptor) would in most systems also then have to be sk~pped in order to provide time for the last sheet to be properly oriented in the output tray. Thus, as stated there, the aforementioned requirements are eliminated by imaging even numbered documents first, regardless of whether a document set comprises an odd or even number of documents.
Various sheet sensors and switches, including those of the type disclosed in the art cited herein, may be .desirably incorporated in the RDH unit and other copier systems disclosed herein. For example, shown in Fig. 1 is a sensing switch 29 in the tray 23 which is actuated whenever any documents are placed therein. Actuation of the switch 29 automatically actuates the machine components associated with the RDH mode of copier operation, including the flipping of the mirror 55. Conversely, when the set of documents are removed ~rom the tray 28, the switch 29 automatically opens to automatically cycle the copier back into its platen-copying mode of operation, The number of documents in the document set being copied is counted during the first copying circulation. A bail set counter switch as shown in the cited art, which is set on top of the stack as it is initially loaded, self-actuates when the last document is fed to indicate the completion of the set count. This bail switch does not need to be reset for subsequent circulations as the document count in the first circulation is stored automatically in the copier logic for job recovery and other functions for all subsequent circulations of that set.
The following is a description of a system for automatically providing the previously noted second method of making pre-collated simplex copy sets from duplex documents.
This system may utilize the duplex/duplex document recircu-lation system and apparatus described above and also the copy sheet handling apparatus of Fig. 4 described above. Yet the simplex copy set output from the duplex document copying is automatically interleaved to provide pre-collated simplex copy sets.
Taking, for example, a five page, three sheet, duplex document set; on the first document copying circulation the even-order pages 2 and 4 [and, if desired, the blank page 6 side] are each copied onto one side of clean copy sheets and those two copy sheets are placed, face-up, in that order, in the duplex buffer storage tray 116 i.e., with copy page 2 face-up on the bottom of the tray and copy page 4 face-up -on top of page 2. Then, on the next document set circulation, the odd-order side document pages~ 1, 3 and 5 are copied onto one side o~ each o~ ~hree more cLean copy sheets from trays 106 and 108. However, paye 1 is fed directly from the transfer station to the output or inishing station. Then, before page 3 iS copied, page 2 i5 fed from the tray 116 directly to the output or finishing station. Then page 3 is copied and fed out as was page 1. Then page 4 is fed out from tray 116 as was page 2. Then page 5 is copied and fed out as was page 1. This provides a full interleaved simplex copy set at the copier output at the end of the second duplex document circulation. Then, on the next document circulation, pages 2 and 4 are again copied and fed into the tray 116 for temporary storage before being ejected as previousLy described. These steps are repeated by a number of times related to the number of desired precollated simplex copy sets.
For the above-described duplex/simplex cop~ing system it is desirable here to provide an automatically actuatable or insertable conventional "Y" sheet path reverser at the output of the sheet feeder 124 from the tray 116, so as to feed the even page simplex copies face-up into the output path 126 without changing their lead to trail edge orientatior. This can be accomplished by automatically reversing the direction of motion of the sheet feed rollers 125 shown downstream of the feeder 124 as soon as the trail edge of the sheet clears the feeder 124. Alternatively, another bottom feeder, feeding in the opposite direction from the feeder 124, coula be placed at the other end of the tray 116.
Maintaining face-up orientation of these even page copy sheets is desired here to match the face-up orientation here of the odd page copies coming from the transfer station.

This feeding o~ even page copies directly to the output from tray 116 is clearly preferable to feeding copies from the tray 116 back through the trans~er station 112 before they are outputed from the copier, since the latter path would require additional time and the undesired transfer and fusing of "background" contamination on the blank backs of these simplex copy sheets.
It will be noted that to maintain forward serial page order collation of the outputed simplexed copy sets with the particular copy sheet paths of Fig. 4 that an inverter, as shown in the output path to tray 130, is needed to provide face-down output, since this particular copy sheet output path otherwise has a face-up output for simplex copies.

Claims (7)

CLAIMS:

1. In an automatic pre-collation copying system for pre-collation recirculating copying of a set of duplex original documents, from a document storage means, at a docu-ment imaging means of a copier for copying the documents onto copy sheets to form pre-collated copy sets, wherein said copier has at least one copy sheet supply means and a separate copy sheet intermediate storage means and a copy sheet output means, and wherein said copier has an image transfer station for transferring images of the documents onto one side of copy sheets fed from either said copy sheet supply means or said copy sheet intermediate storage means, the improvement comprising: duplex document recirculation means for multiply-circulating said set of duplex documents in a recirculation path from said document storage means to said document imaging means for copying all of one sides of said documents once in each circulation and for returning said documents back to said same document storage means in each circulation, said duplex document recirculation means including inversion means for inverting said circulating documents in each circulation before they are returned to said document storage means relative to their initial orientation so that on alternate circulations of said documents alternate sides of said documents are copied by said document imaging means, and duplex copy sheet handling means for feeding all of the copies, made on one of the alternate circulations of the duplex documents, from said copy sheet supply means through said transfer station and into said copy sheet intermediate storage means, and for feeding all of the copies, made on the other of the alternate circulations of the duplex docu-ments, from said copy sheet intermediate storage means through the transfer station again, inverted, and to said copy sheet output means, so that pre-collated duplex copy sets are produced at said copy sheet output means on alter-nate circulations of said duplex documents by said duplex document recirculation means; means for selectively feeding simplexed copy sheets from said copy sheet intermediate storage means directly to said copy sheet output means without passing through said transfer station on alternate said duplex document circulations, and means for feeding simplexed copy sheets made on the other alternate said document circulations from said transfer station to said copy sheet output means alternately and interleaved with copy sheets fed thereto from said intermediate storage means to form complete simplex copy sets at said output means from said duplex document set.

2. A method of making pre-collated duplex copy sets from a set of duplex documents by recirculating the set of duplex documents past an imaging station for individual copying by a number of circulations related to the desired number of copy sets, comprising: automatically circulating the duplex documents from a duplex document set to the imaging station and returning them to the document set inverted from their original orientation, so as to copy opposite sides of the duplex documents alternately on alternate circulations of the document set, and automatically copying one side of each duplex document in the order in which they are so circulated onto one side of corresponding copy sheets in one alternate circula-tion of said documents, and copying the other side of each duplex document on the other sides of the same copy sheets in the other alternate document circulation, to provide pre-collated duplex copy sets; further including the steps of selectively alternatively providing pre-collated simplex copy sets, by copying the duplex documents in each circulation individually onto different sets of individual simplexed copy sheets, feeding the set of simplexed copy sheets made on the alternate document circulation to a temporary storage area; and feed-ing copy sheets made on the other alternate document circulation to the output of the copier alternately and interleaved with copy sheets fed from said temporary storage area to form a complete simplex copy set from said duplex document set, and repeating the above steps to provide multiple pre-collated simplex copy sets from said duplex document sets.

3. The method of Claim 2, wherein said simplex copy sheets are sequentially fed into the top of said temporary storage area in the copying of documents in one document circulation, and individually removed from the bottom of said storage area and fed directly to the output of the copier alternately with the copying of individual documents in the next document circulation.

4. A method of producing pre-collated simplex (one-sided) copy sheet sets at the output of a copier from duplex (two-sided) original document sheets which are recirculated to the imaging station of the copier comprising the steps of:
copying only the first sides of said duplex document sheets in a first copying circulation thereof onto one side of copy sheets as simplex copy sheets, temporarily storing in said copier said simplex copy sheets made on said first copying circulation of said duplex documents as an intermediate buffer set, copying the opposite sides of said duplex documents onto additional simplex copy sheets in a second copying circu-lation and feeding said additional simplex copy sheets as they are made to the copier output alternately and interleaved with copy sheets fed from said buffer set to produce a com-plete precollated simplex copy sheet set from said duplex document sheets, and alternately repeating the above first and second copying recirculation steps to form plural, precollated complex copy sheet sets.

5. The method of claim 4, wherein said intermediate buffer set is temporarily stored in said copier in a buffer set tray, and said simplex copy sheets are fed into said buffer set tray from the top thereof and are fed out directly from the bottom thereof to the output of the copier without inversion or changing their lead to trail edge orientation.

6. The method of claims 4 or 5 wherein said first sides of said document sheets copied in said first copying circulation are the even page sides thereof and the odd page sides thereof are copied in said second copying circulation.

7. The method of claims 4 or 5 wherein said simplex copy sheets are all made by passing through a single transfer station of said copier and wherein said simplex copy sheets are fed from said intermediate buffer set directly to the copier output without passing through said transfer station on said second and alternate said duplex document circulations, and wherein said simplex copy sheets made on the other alter-nate said document circulations are fed directly from said transfer station to said copier output alternately and inter-leaved with said copy sheets fed to said copier output from said intermediate buffer set to form complete simplex copy sets at said copier output from both sides of said duplex document set.