Note: Descriptions are shown in the official language in which they were submitted.
f7
RECIRCULATING DOCUMENTS DUPLEX COPIER
The present invention relates to an improved
automatic document handling system for providing pre-
collation duplex copying.
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
1~ and the individual original documents being copied.
The providing of duplex copying capabilities and pre-
collation copying capabilities greatly complicates and
increases the copier document and copy sheet handling
complexities.
The term "duplex copying" may be more speci-
fically 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,
to which the present invention particularly relates,
the images of ~wo successive simplex document sheets,
which have images on only one side, are copied onto
opposite sides of a single copy sheet. In the print-
ing industry, as opposed to the copier lndustry, two-
sided copying may be referred to as "backing-up" rather
than duplex copying.
In a set of duplex documents or copy sheets,
odd pages 1, 3, 5, etc., will typically appear on the
first sides, with even pages 2, 4, 6, etc., on the
second sides, respectively~ If there are an odd number
of pages in the set of duplex sheets the backside of
the last sheet will typically be blank (empty). In
contrast, in a set of simplex document or copy sheets,
, ~
the number of the sheet will typically also correspond
to the page number. Thus, an odd number of simplex
document sheets will normally have an odd number of
page images.
The duplex copying of the copy sheets (for
either duplex/duplex or simplex/duplex copying) may
be done by first making in the copier processor a set
of simplexed copy sheets (printed only on their first
sides) of only the odd or the even document pages and
temporarily storing those simplex copy sheets in a
duplex buffer tray, and then feeding them back through
the same copying processor for a second pass printing
of the opposite order (even or odd page) document images
on the opposite .sides of the copy she~ts. 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
Nos. 3,615,129, issued October 26, 1971 to W. A. Drawe,
et al.; 3,645,615, issued February 2~, 1972, to
M. R. Spear, Jr.; and 3,851,754, issued October 15,
1974, to E. E. Drexler et al. on duplex/duplex. Of
particular interest as disclosing a duplex copying
system which is also a pre-collation copying system
are U. S. Patents Nos. 3,630,607, issued December 28,
1971, to ~. Korn and 4,116,558, issued September 26,
1978, by the same assignee in the name of J. A. Adamek
et al
~he present invention is an improvement over
said Adamek Patent No. 4,116,558 for automatically
achieving copying and storage of even page numbered
copies of simplex documents in the duplex buffer tray
to avoid variable output inversion or copying of a blank
page when an odd number of simplex documents are being
duplex copied, as indicated in that patent to be de-
sirable, and for achieving this feature under the fur-
ther diEficulty oE copying the documents in reverse
~G~867
3 -
(decending) serial page order with a different type
of document handling system. The description beginning
with the last paragraph of Column 8 of said Adamek U.
S. Patent is particularly noted by way of background
~or this application.
A desirable feature for a copier is to provide
automatic document recirculation for pre-collation copy-
ing. 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 Columns 1-4, and the above-cited
Adamek patent, such pre- collation copying systems
provide a number o~ 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 recirculates. On-line
finishing and/or removal of the completed copy sets
may be provided while additional copy sets are being
made from the same document set.
However, a disadvantage of pre-collation copy-
ing systems is that the documents must all be repeatedly
circulated, and copied in a pre-determined order only
once in each circulation, by a number of circulations
equivalent to the desired number of copy sets. Thus,
it may be seen that increased document handling is
necessitated Eor a pre-collation copying system, as
compared to a conventional postrcollation copying sys-
tem. Maximizing document handling automation and copy-
ing cycle efficiency is particularly importan~ in pre-
collation copying. I~ the document handler cannot cir-
culate and copy documents in coordination with the copy
sheets in the correct order, the total copying time
~or each copy set will be increased.
In a post-collation copying system, all the
67
- 4 - ~
desired copies are made at one time from each document
page and collated by being placed in separate sorter
bins. The document set need only be circulated once
and multiply copied to fill bins of the copy sheet
sorter or collator with the corresponding number of
copy sets desired. However, the number of copy sets
which can be made in one circulation is limited by the
number of available bins, and the sorter adds space
and complexity and is not well suited for on-line fin-
ishing.
Some examples of art relating to pre-colla-
tion document handling systems of the type disclosed
herein, in which each document ~heet is withdrawn from
the bottom of a document set stack for copying once
in each circulation and then returned to the top of
the document stack for repeated copying circulations
include: German Patentschrift 1,128,295, 25 October
1962; and U. S. Patents Re. 27,976, (originally U. S.
3,499,710, issued March 10, 1970) to L. W. Sahley; U.S.
3,536,320, issued October 27, 1970, to D. R. Derby;
V. 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. Howard, et al.; U. S. 3,888,579, issued
June 10, 1975, to V. Rodek et a~.; and U. S.
3,937,454, issued February 10, 1976, to R. H. Colwill.
A recen~ example of a pre-collation copying system of
this type, with circuitry and switches for counting
the number of documents recirculated and for counting
the completion of each set circulation, and face~up
loading of the document stack, i5 shown in U. S. Patent
No. 4~076,408, issued February 28, 1978, to M. G. Reid
et al., and in the U. S. Patent Office Defensive Publi-
cation T957,006 of April 5, 1977, by
-- 5 --
M.G. Reid, et al.. Other examples of document sheet
sensors are disclosed in U. S. Patent 3,790,158, issued
February 5, 1974, to J~ E. Summers et al..
A recent example of an N to 1 order duplex
or simple~ pre-collation copying document recirculation
system is disclosed in article No. 16332, pp. 49 - 52
of the November 1977 issue of "Research Disclosure",
published by Industrial Opportunities, Ltd., Homewell,
Havant, Hampshire, U. K.. A corresponding
U. K. application No. 2,000,749A was published
17 January 1979.
Further examples of copier systems with docu-
ment and sheet handling control systems are described
in U. S. Patent Nos. 4,062,061, issued December 6, 1977,
to P. J. Batchelor et al.; 4,078,7~7, issued March 14,
1978, to L. E. Burlew et al.; 4,099,150, issued July
4, 1978, to J. L. Conin; 4,123,155, issued October 31,
1973, to W. L. Hubert; 4,125,325, issued November 14,
1978, to P. J. Batchelor et al.; and 4,144,550, issued
March 13, 1979, to J. M. Donohue et al
While conventional integral software incor-
poration into the copier's general microprocessor logic
circuitry and software of the functions and logic de-
fined herein as taught by the above is preferred, it
will b~ appreciated that the functions and systems
disclosed herein may be alternativPly conventionally
incorporated into a copier utilizing any other suitable
or known copier software or hard wired logic systems,
cam-bank switch controllers, etc.. The output control
of the exemplarly sheet handling systems disclosed
herein may be accomplished by activating known elec-
trical solenoid controlled sheet deflector fingers and
drive motors or their clutches in the indica~ed seq-
uences, and conventional sheet path sensors or switches
may be utillzed for counting and keeping track of the
~6--
positions of documents and copy sheets.
Certain aspects of the duplex copying exem-
plary system here are disclosed in German OLS
2,828,6~9, published March 1, 1979, and in U. S.
patent 4,166,614 issued September 4, 1979.
A preferred feature of the invention is to
provide, in a document handling apparatus for plurally
recirculating a set o~ simplex original document sheets
to a copier to be copied onto both sides of copy sheets
to ~orm pre-collated duplex copy sets, an improvement
comprising; means for circulating and copying the docu-
ments in reverse (decending) serial page order beginning
with the last sheet in the document set and ending with
the first sheet in the document set, odd/even determin-
ing means for automatically determining whether thereare an odd or an even number of original documents in
said document set before they are copied; and copying
control means, controlled by saicl odd/even determining
means, to inhibit copying of the last and alternate
sùbse~uent documents on the first copying circulation
of said document set in response to a determination
by said odd/even determining means that there are an
odd number o~ original documents in said set, and to
inhibit copying of the next-to-las~ and alternate sub-
sequent documents on the first copying circulation ofsaid document set in response to a determination by
said odd/even determining means that there are an even
_ 7~ 6~7
number of said original documents.
It is a further preferred feature of the in-
vention to place a set of simplex original document
sheets in a collated face-up stack of 1 to N page order
which are individually circulated from the bottom of
the stack to the platen of a copier and back to the
top of said stack in N to 1 order, with N being the
page number of the bottom page of said document stack,
wherein said odd/even determining means determines
whether N is an odd or even page number, and wherein
if N is an odd number, the document sheets are copied
in the first copying circulation as controlled by said
copying control means in the copying order sequence
N minus 1, N minus 3, N minus 5, etc., up to the total
number of document sheets in said document set, and
in at least the second copying circulation all the
document pages are copied and the Nth document page
is ~irst copied on only one side of a copy sheet as
a simplex copy, and in the last copying circulation
that same document set is copied in the copying sequence
N, N minus 2, N minus 4, etc., ancl wherein if N is an
even number, the documents are copied in the first
copying circulation in the order ~l, N minus 2, N minus
4, etc., and copied on the last copying circulation
in the order N minus 1, N minus 3, N minus 5, etc~.
Pre~erably said odd/even determining means
comprises means to circulate the document set once
before it is copied and count the number of sheets in
that non-copying circulation~
6~ .
-7a-
Various aspects of the invention are as follows:
In a document handling apparatus for plurally
recirculating a set of simplex original document sheets to
a copier to be copied onto both sides of copy sheets to
form pre-collated duplex copy sets, the improvement com-
prising: means for circulating the documents in reverse
(descending) serial page order beginning with the last
sheet in the document set and ending with the first sheet
in the document set, odd~even determining means for auto-
matically determining whether there are an odd or an evennumber of original documents in said document set before
they are copied, and copying control means, controlled by
said odd~even determining means, to inhibit copying of
the last, or next to last, and alternate subsequent docu-
ments on the first copying circulation of said documentset in response to a determination by said odd/even
determining means whether there are an odd or even
number of original documents in saicl set to provide
properly collated output duplex copy sets without variable
output inversion.
..9
.~ ' .
36~ j
.,~
-7b-
In the method of recirculatively copying
a set of original documents in. a copier onto both sides
of copy sh.eets to form pre-collated duplex copy sets,
including circulating the document set in reverse
(descending) (N to 1) serial page order beginning with
the last sheet (N) in the document set and ending with
the first sheet (1) in the document set, the improvement
comprising the steps of:
automatically determining wh.ether there are
an odd or an even number of simplex original documents
in said document set by counting the simplex documents
as they are so circulated before they are copied,
in the first copying circulation of the docu-
ment set, copying in said N to 1 order only the last
(Nth) and subsequent alternate simplex documents or
alternatively only copying the n~xt-to-last (N minus
1) and subsequent alternate simplex documents automa-
tically in response to said deter~ining of whether there
are an odd or even number of simplex documents in said
set, and
in all intermediate copying circulations of
the document set, copying all of said simplex documents
in said N to 1 order, and
in the last copying circulation of the document
~5 set, copying the alternate simplex documents not copied
on said first copying circulation,
to provide a properly collated output of duplex
copy sets having consistent copy sheet output inversion.
~ ' .
, . ..
\ -~
-7c- ~ 7
A method for recirculatively copying a set of
simplex original documents in a copier onto both sides of
copy sheets to form pre-collated duplex copy sets compri-
sin~ the steps of. circulating the documents in reverse
(descending) serial page (N to 1) order beginning with
the last sheet N in the document set and ending with the
first sheet (1) in the document set, automatically
determining whether there are an odd or even number of
original documents in said document set by counting the
documents as they are so circulated before they are copied,
copying only the next-to-last (N minus 1) and subsequent
alternate documents on the first copying circulation of
said document set in said N to 1 order automatically in
response to said determination that there are an odd
number of original documents in said set, or alternately
automatically copying only the last (N) and alternate
subsequent documents on the first copying circulation of
said document set in said N to 1 order in response to
said determination that there are an even number of said
original documents in said set, and copying all of said
documents in said N to 1 order in al:L intermediate copy-
ing circulations of said document set, and on the last
copying circulation, copying the alternate documents not
copied on the first copying cixculat:ion, to provide
properly collated output duplex copy sets with consistent
copy sheet output inversion.
In a document handling apparatus for plurally
recirculating a set of simplex original document sheets
to a copier to be copied onto both sides of copy sheets
to form pre-collated duplex copy sets, the improvement
comprising: means for circulating the documents in reverse
(descending) serial page order beginning with the last
sheet in the document set and ending with the first sheet
in the document set, and odd/even determining means for
automatically determining whether there are an odd or an
even number of original documents in said document set
before they are copied, and copying control means, controlled
67
-7d-
by said odd~even determining means, to control the feeding
of copy sets in response to a determination by said odd/even
determining means whether there are an odd or even number
of original documents in said set to provide properly
collated output duplex copy sheets.
In a method of recirculatively copying a set of
original documents in a copier onto both sides of copy
sheets to form pre-collated duplex copy sets., including
circulating the documents in reverse (descending) serial
page order beginning with the last sheet in the document
set and ending with the first sheet in the document set,
automatically determining by odd/even determining means
whether there are an odd or an even number of original
documents in said document set before they are copied by
circulating said document set in a ~irst single non-
copying circulation before any of the documents are copied
and counting the number of document sheets which are
circulated in said first, non-copying circulation, and
controlling the feeding of copy sets, in response to a
determination by said odd/even determining means whether
there are an odd or even number of origina1 documents
in said set to provide properly collated output duplex
copy sheets.
A method for recirculativ~ly copying a set of
simplex original document sheets in a copier onto both
.sides of copy sheets to make plural properly collated
duplex copy sets by pluraly recircula~ing said document
~ esC~ 5
sheets for copying in reverse (~e~e ~i~) serial page
order (N to 1) beginning with the last sheet (N) in the
document set and ending with the first sheet (1) in the
document set, characterized by: automatically determining
-7e~ 867
whether there are an odd or an even n~nber of simplex
original document sheets in said document set by counting
the total number of document sheets in the set as they are
circulated in a first, single, non-copying circulation,
before any documents are copied, automatically in response
to the selection of duplex copying from said simplex docu-
ments; then, in subsequent (copying) circulations of the
document set, automatically in response to said deter-
mining that there are an odd (not even) number of simplex
documents in said set and said selection of duplex copy-
ing, copying said last (Nth) document onto only one side
of a copy sheet to make a simplex end copy sheet for each
copy set, and properly inverting this simplex end
copy sheet to maintain proper collation and orientation
with the other copy sheets in the copy set, which other
copy sheets are then duplexed by being copied on both
sides from the other document sheets of the document set,
to provide properly collated output duplex copy sets.
A method for recirculatively copying a set of
simplex original document sheets in a copier onto both
sides of copy sheets to make plural properly collated
duplex copy sets by plurally recirculating said document
sheets for copying in reverse (descehding) serial page
order (N to 1) beginning with the last sheet (N) in the
document set and ending with the irst sheet (1) in the
document set, characterised by the steps of
automatically determining whether there are
an odd or an e~en number of simplex original document
sheets in said document set by counting the total number
of document sheets in the set as they are circulated in
a first, single, non-copying circulation, before any
documents are copies;
then further circulating said documents and
(a) automatically in response to said determining
that there are an odd (not even) number of simplex original
~.~
..
~ ~L6~LI!367
-7f-
documents in said original document set and said selection
of duplex copying, copying said last ~Nth) document onto
only one side of a copy sheet to make a simplex end copy
sheet for each copy set, and properly inverting this
simplex end copy sheet to maintain proper collation and
orientation with the other copy sheets in the copy set,
which other copy sheets are duplexed by being copied on
both sides from the other document sheets of the document
set, to pro~ide properly collated output duplex copy sets,
each such duplex copy being produced by copying from an
even original document on to one side of the copy sheet
and from the next lower numbered odd original document
in the original document set on to the other side of the
copy sheet, or
(b) automatically in response to said determining
that there are an even (not odd) number of simplex original
documents in said original document set, copying all the
documents on to opposite sides of respective copy sheets
to provide properly collated duplex copies by copying
an even document on to one side of each copy sheet and
the next lower numbered odd document in the document set
on to the opposite side of the copy sheet.
A method for recirculatively copying a set of
simplex original document sheets in a copier onto both
sides of copy sheets to make plural properly collated
duplex copy sets by plurally recirculating said document
sheets ~or copying them in reverse (descending) serial
page order (N to 1) beginning with the last sheet (N)
in the document set and ending with the first sheet (1)
in the document set, characterised by the steps of
automatically determining whether there are
an odd or an even number of simplex original document
sheets in said document set by counting the total number
of document sheets in the set as they are circulated in
a first, simple, non-copying circulation, before any docu-
ments are copied, automatically in response to the selection
~iq
~ ..
6~
7~ ~
of duplex copying from said simplex documents;
then ~urther circulating said documents and
[a) automatically in response to said determining
that there are an odd Inot even) number of simplex original
documents in said original document set and said selection
of duplex copying, copying said last (Nth) document onto
only one side of a copy sheet to make a simplex end copy
sheet for each copy set, and properly inverting this
simplex end copy sheet to maintain proper collation and
orientation with the other copy sheets in the copy set,
which other copy sheets are duplexed by being copied on
both sides from the other document sheets of the document
set, to provide properly collated output duplex copy sets,
each such duplex copy being produced by copying from an
even original document on to one side of the copy sheet
and thereafter copying from the next lower numbered odd
original document in the origlnal document set on to the
other side of the copy sheet, or
(b) automatically in response to said determinin~
that there are an even (not odd) number of simplex original
documents in said original docume~t set, copying all the
documents on to opposlte sides of respective copy sheets
to provide properly collated duplex copies by first copying
an even document on to one side of each copy sheet and
then copying the next lower numbered odd document in the
document set on to the opposite side of the copy sheet,
and
stacking said duplex copies with the odd numbered
sides of the copies face-up and in reverse serial number
order (N to 1) from bottom to top of the stack.
Further features and advantages of the invention
will be better understood by reference to the following
description, and to the drawing forming a part thereof,
wherein:
The Figure is a partial side view of an exemplary
copier and a document feeder therefor incorporating the
present invention.
67
Referring to the exemplary copier 10 shown
in the Figure, and its exemplary automatic document
feeding unit 20, it will be appreciated that various
other recirculating document feeding units and copiers
may be utilized with the presPnt invention, including
various ones disclosed in the above-cited references.
In the recirculating document handler (RDH)
20 here, individual original documents are sequentially
fed from the bottom of a stack of documents (placed
by the operator face-up in the document storage area
or stacking tray 24) to the imaging station 26, which
is the conventional platen of the copier 10, to be
conventionally imaged onto a photoreceptor 12 for the
making of copies in a conventional xerographic mannerO
The document handler 20 has conventional switches such
as 29 for sensing and counting the individual documents
fed from the tray 24, i.e., counting the number of docu-
ment sheets circulated. A conventional resettable bail
and its associated switch 31 indicates the completion
of each circulation o the complete document set and
then is automatically reset on t~e top of the stack
before the next circulation. The document feeder 20
is selected or adapted to sexially sequentially feed
the documents, which may be conve~ntional sizes and
weights of sheets of paper or plastic containing infor-
mation indicia to be copied, e.g., printed or typed
letters, drawings, prints, photographs, etc.. A bottom
feeder 32 feeds the bottom document sheet, on demand,
to a platen belt 30 which moves the document into re-
gistration over the copier platen. In this documentfeeder 20 each document is inverted as it is fed from
the tray 24 to the imaging station 26 around a first
inverting path 40.
After the document has thus been turned over
once at 40 and copied, there is a decision gate 60 in
the document path after the downstream end of the platen
~6~L8~i~
g
belt 30 here, comprising pivotable deflector fingers,
which determines the further recirculatory movement
of the documents through a selected one of two different
return transport paths back to the tray 24. These two
paths are a Eirst (simplex) transport path 54 and a
second (duplex) transport path 58. The second or duplex
transport path 58 returns the documents to their storage
area 24 for restacking with effectively only a single
inversion. In contrast, the first or simplex transport
path 5~ transports the documents around a second invert-
ing path 54 and returns them to the same restacking
tray after having been inverted twice. Therefore, the
solenoid or other actuation of the selector gate 60
determines whether the documents are recirculated with
a total of one or two inversions. With two inversions
(the simplex path 54) the same sides of the documents
are exposed in each circulation and are restacked in
the tray 24 in each circulation in their original orien-
tation. With one inversion (the duplex path 58) the
documents are restacked in the tray 2~ inverted from
their previous orientation, which provides for copying
of the opposite sides or faces of~ the documents on their
next circulation. This is only used for copying duplex
documents. The exemplary duplex path transport 58 here
is provided by a reversable three roller sheet inverter
as shown.
Both the simplex transport 54 and duplex trans-
port 58 continuously restack the sheets after they are
copied on the top of the stack of sheets in the tray
~4. Thus, continuous multiple recirculations for pre-
collation copying can be provided.
The exemplary copier 10 processor and its
controller lO0 will be described in further detail.
It provides duplex or simplex pre-collated copy sets
from either duplex or simplex original documents copied
by the RDH 20. Two separate copy sheet trays 106 and
L86~
-- 10 --
107 are provided here to feed clean copy sheets onto
which the images of the documents are to be printed.
The control of sheet feeding is by the machine con-
troller 100. The controller 100 is preferably of the
known programmable microprocessor type exemplified by
the patents cited in the introduction, which conven-
tionally also controls all of the other machine fun-
ctions described herein including the operation of the
document feeder, the document and copy sheet gates,
feeder drives, etc..
For pre-printed or blank covers or other non-
copy inserts additional inserter trays such as 108 can
be provided, if desired, ~or direct output without print-
ing, but interleaved with the copies.
The copy sheets are fed ~rom trays 106 or 107
to the conventional xerographic transfer station 112
for imaging one side thereof, then to the conventional
fusing station 114. From there, depending on the posi
tion of a duplex selector finger or gate 118, the copy
sheets will be de~lected either into a duplex buffer
intermediate storage tray 116 for duplex copies, or
into the copy output path of the copier via an output
transport 126. The copy sheets stacked into the duplex
tray 116 are stacked image face-up in the order in which
they were copied. The duplex tray 116 here includes
a bounce reverser 120 and jogger~normal force wheels
122 for assisting the stac~ing of copy sheets therein
and assistance in bottom feeding from the duplex tray
116 by a bottom feeder 124. For duplex copying the
previously simplexed copy sheets in the tray 116 are
fed by the feeder 12~ back to the transfer station 112
for the imaging of their second or opposite side page
image. Such now-duplexed copy sheets are then fed out
past the now-opened gate 118 into the same output trans-
port 126. The output transport 126 transports the
finished copy sheets to an output tray, or, preferably,
~L6~86~7
to a finishing station 140 for the stapling, stitching,
gluing, binding, and/or off-set stacking of the com-
pleted, precollated, copy sets. The copy sheet may
be stacked in the finisher in a compilier tray in the
order produced without an inverter with the system
dis d osed here.
By way of further background, a known problem
with reproducing machines which must do both simplexing
and duplexing is the maintaining of proper collation
of the copy sheets in the output tray. For example,
for simplex copy sheets generated in reverse serial
order, the copy sheets would be properly collated if
they are output stacked in that order (N to 1), and
stacked face-up in the output tray. Thus, when the
operator picks up the stacked set of completed copy
sheets, it will be in the proper forward serial page
order (1 to N~ from the top of the stack to the bottom.
The same is true for duplex copies, with the additional
requirement that a lower document page number be on
the top of the copy sheet and the next higher document
page number be on the bottom of the same copy sheet,
so that the completed duplex copy set is in the order
1/2; 3/4; 5/6; etc~. ~ di~ficulty is that most dual
pass duplex copying systems inherently have an inversion
of a duplex copy sheet within the processor as the
duplex copy sheet is returned to the transfer station
from the duplex tray ~or the printing of the second
side image onto the back of the duplex copy sheet.
Thus, typically a duplexed copy sheet receive~ one more
inversion than a simplexed copy sheet. Accordingly,
the output path for a simplex copy sheets is typically
different (i.e., contains one more or one less inver-
sions) than the output path for duplex copy sheets in
order to maintain the proper collation order of the
output sheets.
It is known ~hat this creates a particular
~3L6~67
- 12 -
problem when there is an odd number oE document pages
to be copied onto a duplex copy set. In that caser
the last page of the set of duplexed copies is really
a simplex copy, because with an odd number of original
document pages ~he last copy sheet page in the copy
set will only have an image on one side thereof, and
the other side will be blank. It is known from the
above-cited Adamak patent, for example, to be undesir-
able to run this last duplex copy sheet page through
the transfer station for the pseudo-printing of a blank
image on the backside thereof in order to obtain an
additional inversion, since this wastes processing time
and also can cause undesirable background contamination
of the blank backside of this last page sheet. This
can be avoided by printing a last todd) page of the
duplex copy set on only one side of a clean copy sheet
fed from a copy sheet tray, rather than from the duplex
buffer tray, i.e., only running this par~icular copy
sheet through the processor once. However, this results
in the last duplex copy sheet having a different number
of inversions, and, therefore, apparently requiring
its inversion in order to maintain its collation with
the rest of the duplex copy sheets if copied in forward
serial order. This inversion adds an addi~ional time
delay and potential paper jam site, as well as the
additional expense of the inverter mechanism. Further,
in order to treat the last duplex page differently,
it is necessary to know whether an odd or even p~ge
number document is being copied. That is easy to know
if the documents are copied from page 1, in forward
serial order, but not if the first document copied is
the last sheet of an unknown number of documents.
With the present system, these problems are
overcome, and the last odd page of the duplex document
set can be copied on only one side oE a clean sheet
fed from a copy sheet tray and fed out to the copier
- 13 -
output without an additional inverter being required.
Assume, as one example here, a five page (five
sheet) simplex document set, from which 10 pre-collated
copy sets are desired. This is accomplished here with
12 document set circulations.
A first non-copying circulation of this docu~
ment set determines with a count of the sheet sensor
switch 29 in conjunction with bail switch 31 whether
tbere are an odd or even number of documents. Deter-
mining that the number of document pages is odd in thisexample, i.e., that the last document N is 5, the copier
controller 100 in the next (second~ circulation of the
document set skips the first and subsequent alternate
documents and copies only the even pages 4 and 2, in
that order [i.e., copies only pages N minus 1 and N
minus 3] and places those even page copy sheets in the
duplex buffer tray 116. The other document sheets are
circulated in this first copying circulation, but their
copying is inhibited and no corresponding copy sheet
is fed for them in this first copying circulation.
On the next 9 document circulations in this
10 set example (intermediate circulations 3 to 11) all
the documents are copied in the N to 1 order, i.e.,
5, 4, 3, 2, 1. However, the copy sheets for page 5
is fed from the copy sheet tray 107 or 106 ~not the
duplex buffer tray 116) and after receiving page 5 on
only one side thereof is directly outputted, as a sim-
ple~ copy. Page 5 is thus face-up in the output to
the finisher 140, and the first copy sheet out. Docu-
ment page 4 is then copied on a sheet fed from the copy
tray 107 or 106 and fed into the duplex buffer tray
116. The next copy sheet is fed from the bottom of
the duplex tray 11~ This is the copy sheet on which
page 4 had been printed in the previous circulation.
Document page 3 is printed on its opposite face, and,
due to the inherent inversion in the processor output
~6~7
- 14 -
path, this second copy sheet out is placed in the output
path with its page 3 side face-up and its page 4 side
face-down on top of the preceeding page 5 copy sheet.
The next even document page, page 2, is also copied
on a clean copy sheet from tray 106 or 107 and fed into
the duplex tray 116 on top of the preceeding page 4.
The last copy sheet in each set is fed from the duplex
tray 116 and it receives the document page 1 image on
the opposite side of the previous page 2 image and is
likewise outputted. Thus, in each of these 9 document
circulations a complete duplexed outputted copy set
is provided stacked in the finisher 140 in the proper
collated order 1/2; 3/4; 5/blank; and meanwhile the
duplex tray 116 has been refilled with another even-
side buffer set.
On the last (12th) document set circulationin this example the above copying sequence is changed
in ~hat none of the even document pages~ 2 and 4 in
this example, are copied. Thus, l:he duplex buffer tray
116 is emptied out, and not refil:Led, on the last copy-
ing circulation, and the final (lt)th) copy set is pro-
vided, as taught by the above-cited Adamak patent.
If, in the above example, there had been an
even number of documents, e.g. 4, the copier controller
would change the copying sequence and not skip the first
and subse~uent alternate documents being recirculated
in the ~irst copying circulation. Rather, it would
skip pages 3 and 1, the second and alternate documents,
to copy only the even pages 2 and 4 in the first cir-
culation. On the second copying circulation it would~eed the first copy sheet (page 4) to the duplex tray,
not to the output, since it is an even page to be du-
plexed, as described above.
I~, in the above example, ~here had been only
one copy set requested (punched into the copy count
selector switch) rather than 10, then only the first
- 15 -
and second and last document circulations described
above would be utilized. There would be no intermediate
circulations in which all documents were copiedO
It may be seen that by the combination here
of reverse document page order copying but with auto-
matic feeding of only even page copies into the duplex
tray, and the feeding of those even page copies back
to the processor in the order in which they were copied
on their first sides, that proper output collation is
maintained even though the last odd document page copy
i5 effectively simplexed. To express it another way,
with this system, no separate or additional inverter
is required for effectively simplexing the last duplex
copy sheet when there is an odd number of document
pages. Further, this same document handler and copier
can be alternatively utiliæed to produce fully simplexed
copy seks from the same simplex documents if desired,
and these simplex copy sheets will also be in the proper
collated output order, i.e., output stacked in N to
1 order, but face-up, so as to form proper 1 to N page
order copy sets.
It is important to note that with this system,
that the odd lmage page number which is placed on the
second side of the copy sheet being duplexed is the
preceeding (lower) page number, not the succeeding
~higher) page number. That is, page 3 is printed on
the backside of page 4 and not page 5. This is essen-
tial for maintaining proper collation here, where the
copy sheet is outputted with the last printed side up.
This would be true of a straight-through paper path
bottom transfer copier as well as the disclosed top
transer copier wi~h one inversion in the output path
from the ~ransfer station to the finisher. The present
system automatically accomplishes, with this particular
reverse serial order copying system, the placement of
the next lower odd page number on the back of each copy
i7
- 16 -
sheet bearing the immediately previous higher even page
number.
It is also important to note that the present
system properly and consistently handles letterhead
or other pre-printed or pre-punched copy sheet stock
or forms for duplex copying for either an odd or even
number of duplex, or an even number of simplexJoriginals.
In printing onto letterhead paper, page one, the odd
page, must be printed on the front or letterhead side,
not the back sides, of the copy sheet. For pre-punched
sheets the binder holes must be on the left side of
the odd pages. With the present system these restricted
copy sheets can desirably always be placed face-up in
either of the copy sheet trays, yet will always be
properly duplexed, since the proper even page sides
are always printed on the back of the copy sheets first
as they are fed from the copy trays, and then the odd
document pages are copied onto the ront sides of the
copy sheets as they are fed from the duplex tray.
Briefly re-describing the disclosed simplex/
duplex copying system, it will be seen that it does
not require a separate or variable copy output sheet
inverter yet provides proper page order collated output
of all copies, even for those copiers like the "Xerox"
"4000" or "5400" which have an inherent inversion in
the pa~er path output after transfer (rather than a
straight-through paper path). Such a paper path is
disclosed here. There is no feeding of a "blank" side
copy sheet through the processor for the back of a las~
odd copy page, or its inversion. The documents are
alw~ys circulated in N to 1 order (i.e., reverse serial
page order) in all circulations. For this purpose,
the simple~ document set here is placed face-up in the
tray of a document handler which bottom-feeds the docu-
ments to the platen. Before ~y~ is initiated, the
document set is first initially circulated in one non-
6~
- 17 -
copying circulation during which the number of documents
is counted. If an even number of simplex documents
is counted on ~his first "pre-count" circulation, then
on the second (and first copying) circulation the docu-
ments are copied in the order N, N minus 2, N minus4, N minus 6, etc.. That is, when the "pre-count"
circulation determines that the last document is an
even document, then all even documents (only) are copied
in the second document circulation by copying every
other document in reverse order starting with the very
last document N. The odd document pages are circulated,
but not copied. In contrast, if an odd number of docu-
ments is counted in the pre-count cycle, then the last
sheet N of the document set and the alternate subsequent
documents are not copied on the second circulation and
the copying sequence is N minus 1, N minus 3, N minus
5, N minus 7, etc.. This also caus~Qs only even document
pages to be copied in the second ~first copying) cir-
culation even though the last document page is odd
rather than even. Thus, an even side buffer set is
always placed in the duplex tray for e ther odd or even
numbers of documents. After the above-described first
two document circulations, all but the last subsequent
circulations proceed with copying of all document pages
onto copy sheets ~ed alternately from the copy tray
and duplex tray, as disclosed in Xerox Patent 4,116,558.
Then on the last document set circulation, only the
odd document pages are copied, by reversing the copying
sequence for odd and even numbers of documents which
was described above for the second circulation.
Referring now to the duplex/duplex system which
can be compatibly provided here, the duplex documents
may also be loaded face-up and copied in the same N
to 1 (reversed serial) order from the same single docu-
ment tray. Here the document inverter for the duplexdocuments is downstream of the platen rather than up-
- 18 -
stream. Thus, the duplex documents are also first run
through a single dummy (non-copying) circulation, but
with inversion to restack ~he documents inverted in
the DM tray from their initial orientation. Thus, the
even sides of the duplex documents are copied on the
seconcl (first copying) circulation and placed in the
duplex tray so that the proper page order sequence can
be provided in the output of the duplex copy sheets
without an inverter. On all subsequent circulations
(up to the final one) every duplex document sheet is
copied on one side and then inverted before
restacking as described in the above-cited U. S.
Patent 4,166,614 and German OLS 2828669. That
is, all the odd sides are copied on the
third (second copying) circulation onto the opposite
sides of the buffer set fed from the duplex tray, then
all the even sides are copied in the fourth circulation
and placed in the duplex tray, etc., etc.. The duplex
documents are inverted during all but the last circu-
lation. On the last duplex docu!ment copying pass thedocuments are all copied but are not inverted. The_
re~ore, they are automatically re-collated in the docu-
ment handler tray during this last copying circulation.
To improve copy efficiency, an additional
feature may be provided if th~re are only two simplex
documents in the document set. With only two simplex
documents, there is only one copy sheet in each duplex
copy set, so collation is not required. If only two
document sheets are counted in the document set during
the non-copying first circulation, the copying control
100 causes the copier 10 to make multiple rather than
single copies of these first and second document sheets
in the first copying circulation. That is, the copier
automatically switches to a nonprecollation duplex
-- 19 -- ~
copying mode in which the selected number of copies,
(but limited to the duplex tray 116 capacity~ is made
from each document while it is held on the platen with-
out circulation, and all these copy sheets are stored
into the duplex tray and then the next document is
multiply copied onto their opposite sides. If the
number of "copy counter" selected copies exceeds the
duplex tray capacity, the two documents are re-circu-
lated for copying, e.g., for 60 duplex copies of two
documents with a 25 sheet capacity duplex tray, 25
copies are made in the first circulation, 25 in the
second and ten in the third.
While the duplex copying system disclosed
herein is preferred, it will be appreciated that various
lS variations, alternatives or improvements thereon may
be made by those skilled in the art, and the following
claims are intended to encompass those falling within
the true spirit and scope of the invention.
