Recirculating document feed apparatus and method for aligning documents therein

A document feed device, illustrated with a copier machine, for recirculating documents through a processing station. A movable portion of the document feed device is mounted for pivoting movement to expose a lower document feed path. The movable portion contains several document moving rollers but no prime movers, gears or belts; these rolls are driven by frictional contact with each other and ultimately by contact with a set of driven rollers located in the nonmoving portion of the document feed device. The rollers comprising a document moving nip are oppositely skewed relative to the direction of document travel in order to move documents gently toward a reference edge and coefficients of friction of roller materials are chosen to insure correct document alignment.

This invention relates to a recirculating document feed device and more 
particularly, to a device which includes a pivoting portion containing no 
prime movers and a method for aligning documents despite slippage in 
document moving roll nips. 
BACKGROUND OF THE INVENTION 
Paper moving schemes appearing in the art are numerous and include such 
devices as vacuum belts, vacuum trays, wave generators, large diameter 
rollers, soft high friction rollers, hard high friction rollers, and 
leading edge pullers. Means of moving, turning, or transporting said 
devices include chains, belts, blowers, etc. driven by a prime mover such 
as a motor. 
In recirculating document feed devices, a document is passed through a 
processing station and then recirculated so that it passes through the 
processing station again. The cycle can be repeated any number of times 
until the desired number of processing steps have been completed. 
Recirculating document feed devices ordinarily use paper moving schemes 
involving gears and belts, etc. such as described above and as illustrated 
in U.S. Pat. No. 3,661,383. Such systems are subject to difficult document 
retrieval should a jam occur, they are costly relative to the invention to 
be described herein, and are difficult to adjust and maintain. 
The instant invention involves a configuration in which it is possible to 
drive an entire system of paper moving devices by providing only one set 
of driven rolls directly connected to a prime mover and using frictional 
contact between those rolls and additional sets of freely rotating rollers 
to obtain document recirculation. The freely rotating rollers are 
positioned in a pivoting frame which opens to expose the document feed 
path to provide for ease of document retrieval, ease of mechanism 
adjustment, ease of maintenance and easy book copying. This arrangement 
provides a reliable low-cost drive which is quiet and safe because of its 
freedom from belts, chains, or gears. This is also important from a safety 
viewpoint since recirculating document feed devices are in an area of user 
access. 
An additional advantage of the invention is the ability to bias the side of 
a moving document against a side reference edge with a controlled force so 
as not to crumple the edge of the document by making use of the principles 
described in U.S. Pat. No. 4,179,117. In an especially innovative and 
advantageous design, the invention incorporates a large freely rotating 
roller which forms a part of two roll nips in two different document feed 
paths and thus creates unusual problems in document side edge referencing 
in both paths. The invention herein solves that problem. 
Additionally, the beam strength of documents when driven around the 
substantially 180.degree. bends of a recirculating document feed path 
creates slippage in roll nips and therefore unusual problems in 
maintaining alignment of the document against the side reference edge. 
Moreover, a document in two roll nips may be pulled through one nip by the 
other, again creating an unusual aligning problem. The invention herein 
provides a method for solving these problems. 
SUMMARY OF THE INVENTION 
This invention is embodied in a document feed device which includes a first 
set of roll nips provided in a first document path, the roll nips 
comprised of driven rolls and a first set of freely rotating rollers. The 
driven rolls are placed on the underside of the first document path 
protruding slightly above the plane of the path to individually mate with 
individual ones of the first set of freely rotating rollers which are 
thereby powered through contact with the driven rolls. A reference edge is 
provided along one side of the document feed path to provide a surface for 
referencing documents. The drive rolls and the first set of freely 
rotating rollers are skewed to the direction of document travel to urge 
documents against the reference edge. 
The document feed device further includes a second document path for 
receiving documents from the exit of the first path and returning them to 
the entrance of the first path. The second document path contains a second 
set of roll nips comprised of two groups of freely rotating rollers. The 
first group of freely rotating rollers is situated on the underside of the 
second document path and each roller protrudes slightly into the plane of 
that path to mate individually with individual ones of the second group of 
freely rotating rollers. The second group of freely rotating rollers are 
powered through contact with the first group of freely rotating rollers 
which are powered ultimately by contact with the driven rolls. The first 
and second groups of freely rotating rollers are skewed to the direction 
of document travel in the second path to urge documents into a second 
reference edge positioned along one side of the second document feed path. 
The document feed device contains a movable cover portion mounted about a 
pivot to expose the first document feed path, thus breaking the first set 
of nips when opened. When opened, none of the freely rotating rollers can 
operate since the only source of power is connected to the drive rolls 
which are not a part of the movable portion. 
In a particular embodiment, large rollers are provided to form a part of 
both the first and second set of roll nips, that is, the large roller 
mates with a drive roll to form one of the first set of nips in the first 
document path and also extends into the second document feed path to mate 
with a roller of the second group of freely rotating rollers to form one 
of the second set of nips. In this embodiment, the driven rolls are skewed 
between zero and 0.4 degrees for urging a document away from the first 
reference edge, while the first set of freely rotating rollers, the large 
rollers are skewed between zero and 0.6 degrees for urging documents 
toward the first reference edge. The coefficient of friction of the first 
set of freely rotating rollers may be chosen to be greater than the 
coefficient of friction of the drive rolls. 
In this particular embodiment, by virtue of the fact that the first set of 
freely rotating rollers protrude into both document feed paths and urge 
the document toward the reference edge in the first document feed path, it 
moves the document away from the second reference edge in the second 
document feed path. The second group of freely rotating rollers, 
therefore, should have an angle of skew and a coefficient of friction 
relative to the first set of rollers such that a proper alignment of the 
document is maintained in the second path. This requirement is met in the 
described embodiment in an unusual manner since the coefficient of 
friction of the roller urging the document toward the reference edge is 
substantially lower than the coefficient of friction of the mating roller. 
This method of arranging the rollers is advantageous due to slippage of 
the document in the roll nip during document movement toward the reference 
edge and allows the document to follow the lower friction roller when 
slippage is occurring on the higher friction roller. This results since 
the document, when slipping, will follow the roller on the nondriven side 
of the nip.

DETAILED DESCRIPTION 
The document feed device of this invention is useful in many environments 
but is illustrated in this detailed description in conjunction with a 
document copier machine in order to explain its features and its value. 
FIG. 1 shows a document copier machine with an exterior housing 10 
containing a top surface 11 inclined at an angle of approximately 
20.degree. to the horizontal. Positioned on that top surface is a document 
feed path 19, the sides of which are generally defined by reference edge 
13 and spine 14. Document feed path 19 forms a part of a recirculating 
semiautomatic document feed device (RSADF) 15 together with hinged cover 
15' and all associated drive rolls, freely rotating rollers, and guides. 
When cover 15' is closed as shown in FIG. 1, cover 15' and document feed 
path 19 provide an entry slot 12 for the insertion of single documents to 
be copied. After copying, these documents exit from the RSADF through an 
exit slot 17 located in cover 15'. 
A paper cassette 35 is shown in place for feeding copy paper into the 
machine. The completed copy is returned against the face 40 of the 
cassette. 
FIG. 2 is a schematic drawing showing the interior side view of the copier 
machine of FIG. 1 illustrating the document path 18 of the recirculating 
semiautomatic document feed device 15. FIG. 2 also shows the copy paper 
path 36 from cassette 35 and the various processing stations located along 
photoconductive belt 20. 
A document to be copied is manually inserted through input slot 12, where 
it is sensed and driven to queuing gate 44. If no other document is being 
copied, gate 44 is released allowing the document to advance to 
registration gate 46. When the machine is ready, gate 46 is released 
allowing drive rolls 48 and 50 to move the document across the fiber optic 
viewing station 16. The original document, after processing, is either 
delivered to the exit slot 17, or is recirculated for multiple copies by 
return paper path 18 as determined by the position of gate 63. Gate 63 is 
automatically positioned in accordance with the number of copies selected 
by the operator and a count of the number of copies already produced from 
that original document. 
The image of the original document thus scanned is placed upon a continuous 
loop photoconductor (PC) belt 20, which is retained in place by means of a 
guide frame assembly 21. 
The copier machine shown in FIG. 2 takes an electrophotographic two-cycle 
process configuration wherein corona 25 operates as a charge corona to 
place an appropriate electrostatic voltage level on PC belt 20. The image 
of the original document is placed upon belt 20 at imaging location 26 by 
selective discharge, based upon the information contained in the original 
document. This image is then developed by developer unit 30 which places 
toner on appropriate areas of belt 20 as it passes the magnetic brush 
roller 31. 
The paper gating mechanism 34 controls the introduction of copy sheets from 
cassette 35 to the photoconductor belt 20 in appropriate synchronism with 
the movement of the toned image on belt 20. Corona 24 operates as a 
transfer corona to transfer toner from belt 20 onto the copy sheets. The 
copy sheets continue to the fuser comprised of rollers 38 and 39 where the 
toner image is fused to the copy sheet. The toned copy sheet is then 
exited from the machine. 
FIG. 3 shows the machine of FIG. 1 with the cover 15' of the recirculating 
document feed device 15 rotated around the hinges 41 to an open position. 
In this position, the entirety of the document feed path 19 along the top 
surface 11 is exposed to view. FIG. 3 shows document feed path 19 with a 
document reference edge 13 along one side and a spine or rail guide means 
14 positioned along the opposite edge. Entry sensor 42, aligner roll 43, 
queuing gate 44 and registration gate 46 precede viewing station 16 in 
paper feed direction A. All document moving rolls protrude above the plane 
of top surface 11 with rolls 45, 47, 48, 49 and 50 lying within path 19 
and rolls 52, 53 and 54 located across the rail guide means 14 outside of 
the document path. 
The open cover 15' in FIG. 3 shows the corresponding rollers 43', 47', 48', 
49' and 50' which mate with the rolls on the top surface 11 to form roll 
nips when the cover 15' is closed. The open cover in FIG. 3 also exposes a 
manual start button 51 for use when copying books. 
When a single sheet is to be copied and document feed cover 15' is in 
place, entry switch 42 automatically starts machine operation when the 
document is sensed, and aligning roll 43 operates to position the single 
sheet against reference edge 13 and queuing gate 44. After alignment, and 
if there is no preceding sheet in the device 15, gate 44 is dropped and 
mating rolls 43 and 43' move the paper down the feed path 19 in direction 
A to registration gate 46. At the proper point in the machine cycle, gate 
46 is dropped allowing rolls 43, 47 and 48 to move the document across a 
stationary elongated document viewing station 16, the major dimension of 
which is perpendicular to feed path direction A. Rolls 49 and 50 continue 
to move the document out through exit slot 17 or around through the return 
paper path 18 if multiple copies are to be made. 
If multiple copies are being made, the sheet recirculates through document 
path 18 shown in FIG. 2 until it returns to gate 46. Again, at the proper 
point in the machine cycle, gate 46 will drop initiating another copy 
sequence. During this period of recirculation, a next sheet can be 
inserted by hand to aligning roll 43 and moved against the queuing gate 
44. In that manner, once the required number of copies have been made of 
the first document and it has exited through slot 17, gate 44 will drop 
allowing the second document to proceed to gate 46 and repeat the cycle. 
Rolls 45, 52, 53 and 54 together with spine 14 are provided for copying 
books as more fully explained in U.S. patent application Ser. No. 296,683. 
A comparison of FIGS. 1 and 3 show that the document feed device 15 
contains a lightweight, easily movable cover portion 15' pivoted by hand 
to an open position by grasping cover 15' at hand grip 60. This ease of 
movement is made possible by the fact that none of the rollers mounted in 
the pivoting cover 15' are driven except through contact with the drive 
rolls when the cover is closed. As may be observed in FIG. 3, this 
provides an added safety feature since none of the rollers 43', 47', 48', 
49' or 50', which are exposed when the cover 15' is open, are driven when 
the machine is used for copying a book along the exposed paper path 19. 
Referring now to FIGS. 2 and 4, the drive mechanism for recirculation of 
documents is illustrated. Drive rolls 48 and 50 are positioned on the 
underside of first document feed path 19 protruding slightly through the 
plane of that path to form a first driving nip with freely rotating 
rollers 48' and 50'. In the embodiment illustrated, the latter rollers are 
large in circumference and extend upwardly to protrude slightly into 
second document feed path 18 to form a second nip with freely rotating 
rollers 48" and 50". Exactly the same construction is present for roller 
groups 49, 49', 49" and 47, 47' and 47" so that the groups of rollers form 
sets of nips, a first set of nips in document feed path 19, and a second 
set of nips in second document feed path 18. 
A drive motor 62 is shown in FIG. 4 connected to drive roll 48. Suitable 
connecting transmissions, not shown, connect motor 62 with the other drive 
rolls. Motor 62 may also drive other components within the copier machine 
if desired. It should be noted that in the embodiment shown in FIGS. 1-4, 
the nonpivoting portion of document feed device 15 is a part of the copier 
machine itself, that is, the first document feed path 19 is coincident 
with the top surface 11 of the copier machine 10. 
In operation, a paper is fed by hand through entry slot 12 and after 
queuing at gate 44 and registering at gate 46 as previously described is 
fed into that portion of document feed path 19 containing the rollers 47 
and 48. These rollers with the associated freely rotating rollers 47' and 
48' move the document across viewing station 16 and into the nip of 
rollers 49, 49', and 50, 50'. If multiple documents are to be made, the 
document is recirculated into the second document feed path 18 where the 
document is fed in direction B through the rollers 50', 50" and 49', 49" 
and into the nips of rollers 47', 47" and 48', 48". The leading edge of 
the paper is then fed around bend 61 and back into first paper path 19 to 
register against gate 46 prior to beginning the next cycle. 
As may be appreciated, it is important to maintain proper document position 
against reference edge 13 while the document passes across the viewing 
station 16. As a consequence, rollers 48 and 48' are skewed to direction 
A, that is, the direction of document movement along paper path 19 so that 
the paper is urged toward reference edge 13. FIG. 4 shows that roller 48' 
is positioned at an angle such that it tends to drive the paper toward 
reference edge 13 while roll 48 is skewed to direction A in a manner such 
that it tends to urge the document away from reference edge 13. In a 
preferred embodiment, roller 48' is positioned at an angle between zero 
and 0.6 degrees into the reference edge, while the drive roll 48 is 
positioned at an angle between zero and 0.4 degrees away from the 
reference edge. One can be assured that the document will be moved toward 
the reference edge if roller 48' is caused to have a higher coefficient of 
friction than roll 48. The advantage of skewing roll 48 to urge the paper 
away from the reference edge is that this provides control over the force 
moving the paper into the reference edge and thus prevents a crumpling of 
the paper when it engages with edge 13. It should be understood that once 
the document edge is aligned against the reference edge, slippage in the 
roll nip must occur to keep the document from crumpling and thus control 
over the forces moving the document into the reference edge is important. 
Again, that subject is fully discussed in above-referenced U.S. Pat. No. 
4,179,117. 
As one can appreciate from FIG. 4, when large roller 48' is positioned to 
urge paper toward reference edge 13 in paper path 19, it results in moving 
paper away from reference edge 13' when the paper is moving in second 
document feed path 18. Thus, freely rotating roller 48" is skewed to the 
direction of document movement B to urge the documents towards reference 
edge 13'. Again, by choosing the coefficient of friction of roller 48" to 
be greater than roller 48', one can be assured of moving the paper toward 
reference edge 13'. However, in a preferred embodiment of this invention, 
roller 48" is chosen to take a lower coefficient of friction than roller 
48' for the following reasons. As paper is moved around bend 61, the beam 
strength of the paper tends to cause a high drag force in the nip of 
rollers 48', 48" which tends to create slipping in the roll nip. When 
slipping, the document tends to follow the roller on the nondriven side of 
the nip and thus the leading portion of the document is correctly 
positioned against the reference edge by skewing roller 48" toward the 
reference edge. This is advantageously accomplished by a low friction 
roller since it is important to limit the force moving the document into 
the reference edge once the document is against the reference edge. 
Slippage between the document and the roller on the nondriven side of the 
nip must occur at that point to avoid crumpling the document. 
When the leading edge of the document has passed around bend 61 and enters 
the nip of rolls 48 and 48', it tends to be pulled through the nip of 
rollers 48' and 48" thus again creating slippage at that nip. As a result 
of that slippage, the document again tends to slip on roller 48' which is 
on the drive side of the nip (although not itself directly driven) and to 
follow the lower friction roller 48" on the nondriven side of the nip. 
Thus the trailing portion of the document is correctly positioned against 
reference edge 13' and the low coefficient of friction of roller 48" 
prevents document crumpling at the reference edge. 
In a preferred embodiment, roller 48' is positioned between zero and 0.6 
degrees in a manner tending to urge the paper away from the reference edge 
in the second paper path 18 while freely rotating roller 48" is skewed at 
an angle between 1.degree. and 15.degree. to the direction of paper 
movement tending to urge the document toward the second reference edge 
13'. A representative coefficient of friction may be 0.6 to 1.5 for roller 
48' and 0.4 or less for roller 48". A similar analysis can be made for 
rollers 47' and 47". 
Thus, a recirculating document feed device has been described which 
requires no driven components in a hinged cover and in which documents are 
successfully aligned against reference edges for accurate copying even 
though slippage is present in roll nips while the document is being moved 
toward the reference edge. There are modifications to the embodiments 
described which might be made at one's discretion. For example, the single 
large rollers 47', 48', 49' and 50' could be replaced by a plurality of 
rollers and various skewing arrangements might be attempted with different 
device dimensions and/or configurations. 
While the invention has been particularly shown and described with 
reference to a preferred embodiment thereof, it will be understood by 
those skilled in the art that the foregoing and other changes in form and 
details may be made therein without departing from the spirit and scope of 
the invention.