Large document copying system

A system for copying large documents on a large document copier having a large document sheet feeder and a large copy sheet or web feeder with improved convenience and efficiency by inserting the leading edge of the large document into the document feeder from the front of the copier, automatically initially rapidly feeding the large document away from the front of the copier with the document feeder, pausing the feeding of the large document in a position wherein a trailing portion is retained in the document feeder but a substantial portion of the document is at the rear of the copier, so that the front of the large document copier is unobstructed, then inserting a copy sheet or web into the copier from the front thereof for copying, and in response to this and copier activation, first automatically rapidly feeding the large document back in a reverse direction with the large document feeder without copying, up to a position where a leading edge portion of the document is retained by the document feeder, and then, promptly thereafter, automatically again reversing the direction of feeding the document and moving the document at a copying speed synchronized with movement of the copy sheet or web towards the rear of the copier for copying the large document onto the copy sheet or web.

Cross-reference is made to copending applications by the same assignee, 
filed June 1, 1989, as U.S. App. No. 07/359,611 and U.S. App. No. 
07/360,176, respectively, Attorney Docket Nos. D/89090 and D/89089. If any 
claim may be made for the benefit of the priority or filing date thereof 
it is hereby made. 
This invention relates generally to large sheet copying machines, and more 
particularly to an improved but simple and low cost large document and 
copy handling and feeding system for a large sheet or web copying system, 
as, for example, an engineering or architectural drawing copier or the 
like. 
Various types of engineering drawing or other large sheet or web copiers 
are known in the art. An early xerographic engineering drawing copier with 
large document feeding is shown in Xerox Corp. U.S. Pat. No. 3,239,220. 
The following patent disclosures are notes by way of background examples 
of Xerox Corporation large document and large copy sheet copiers, 
including those with document feeders: U.S. Pat. Nos. 4,771,310; 
4,823,663; 4,784,345; 4,714,978; 4,138,102; 4,688,926; 4,690,540; 
4,653,894; 4,666,293; 4,689,471; 4,680,040; 4,693,588; 4,639,122; 
4,766,456; 4,822,978; 4,821,974. 
Some examples of U.S. patents on servo-motor or stepper-motor driven 
original document feeders for copiers, in general, are U.S. Pat. Nos. 
3,888,579; 4,000,943; 4,008,956; 4,144,550; 4,283,773; 4,455,018; and 
4,579,444. 
The "document" here is the sheet (original or previous copy) being copied 
in the copies onto the "copysheet", or "copy". In the terminology herein 
the term "document" or "document sheet" refers to a conventional sheet of 
paper, plastic, or other such conventional individual physical image media 
or substrate, which is usually flimsy, relatively difficult to manipulate, 
and easily damaged. 
Various sheet feeders are used with automated drive rolls and the like in 
various printers and/or copiers, but these feeders are often inappropriate 
for use in feeding large sheets, especially for low cost, slow speed, 
coping machines. It is necessary to feed copy sheets in some of these 
machines measuring, for example, 61.times.91 cm. (24.times.36 inches) or 
91.times.122 cm. (36.times.48 inches), or even uncut webs of much greater 
length. Furthermore, loading of large documents and/or copy sheets 
presents operator handling difficulties and is time consuming. Typically, 
loading and unloading of the large sheets involves critical manual 
handling steps. 
Mishandling or misfeeding of large document or copy sheets in (and to and 
from) a copier can cause wrinkling, buckling, tearing, or other sheet 
damage. It can also cause miscopying, such as skewed, uneven, unevenly 
magnified, or misregistered images. Thus, the loading, starting positions, 
speed (sheet velocity) and direction of movement of the large documents 
and/or copy sheets can be quite critical to commercially acceptable 
copying. 
In the embodiment disclosed herein, one particular disclosed feature 
relates to the interrelationship of large document and copy sheet feeding 
in a large document copier. In such copiers typically the large documents 
are loaded into and fed by constant velocity transport document handler or 
CVT. Typically, a CVT has document feeding roller nips on opposite sides 
of an illuminated imaging slit. Typically, the CVT moves the document past 
an illuminated imaging slit for scanning copying while the document is 
moving at a speed corresponding to the surface speed of the imaging 
surface. The imaging surface may be a photoreceptor, as described here, on 
which an image is developed and transferred to a copy sheet media. In the 
disclosed embodiment of the subject system and apparatus, the documents 
are first acquired and moved by the CVT, without copying, from the front 
to the rear of the machine, stopped and held paused with the trail edge of 
the document in the rear CVT nip, so that the document is out of the way 
of the front of the machine, and before a copy sheet is loaded or fed. 
Then the copy sheet is loaded--unobstructedly. Then, automatically, after 
the copy sheet is acquired, the document is fed back forward at high speed 
until (only) the document lead edge is in the front nip, and then both the 
document and copy sheet are fed rearwardly in coordination for copying. 
The latter steps can be repeated for plural copies made from the same 
document without reloading the document, since the document is not fully 
released by the CVT until after all copying thereof is completed. Other 
disclosed features relate to the DH construction, sensor and trays 
locations, etc.. 
A specific feature of the embodiment disclosed herein is to provide a 
system for copying large documents on a large document copier having a 
large document sheet feeder and a large copy sheet or web feeder with 
improved convenience and efficiency comprising the steps of: inserting the 
leading edge of said large document into said document feeder from the 
front of said large document copier, automatically initially feeding said 
large document away from the front of said large document copier with said 
large document feeder, pausing said feeding of said large document by said 
large document feeder in a position wherein a trailing portion of said 
large document is retained by said document feeder and a substantial 
portion of said large document is removed from the front of said large 
document copier so that the front of said large document copier is 
unobstructed by said large document, inserting a copy sheet or web into 
said large document copier from the front thereof for copying, activating 
said large document copier to copy said large document onto said copy 
sheet or web after said copy sheet or web has been inserted, and, in 
response to said copying activation, first automatically rapidly feeding 
said large document back in a reverse direction with said large document 
feeder without copying, to a position wherein a leading portion of said 
large document is retained by said document feeder, and then, promptly 
thereafter, automatically again reversing the direction of feeding said 
large document with said large document feeder and moving said large 
document away from the front of said large document copier at a copying 
speed synchronized with movement of said copy sheet or web for copying 
said large document onto said copy sheet or web. 
Further specific features provided by the system disclosed herein, 
individually or in combination, include those wherein said large document 
is retained throughout all said steps in said large document feeder 
without substantial slippage or skew, with plural rigidly supported roller 
nips; wherein the response to said copying activation, said large document 
is fed back to the front of said large document copier at a reverse 
direction speed which is substantially faster than said copying speed, and 
then automatically promptly thereafter said large document is again fed 
from the front of said large document copier towards the rear thereof but 
at said copying speed; and wherein in said step of automatically initially 
feeding said large document away from the front of said large document 
copier with said large document feeder said document is fed at a feeding 
speed which is substantially faster than said copying speed; and/or 
wherein said steps are repeated without substantial documents slippage or 
skew with the document retained in said large document feeder until the 
selected number of copies is made from a document before releasing that 
document from said large document feeder. 
Further disclosed specific features include, in a large document copier, 
having a large document sheet feeder for moving a large document at a 
preset sheet feeding copying velocity past a scanning slit in said copier, 
for copying the large document onto a large copy sheet or web fed into 
said copier by a large copy sheet or web feeder feeder, with means for 
inserting large documents into said large document sheet feeder from a 
front side of said copier, and means for inserting copy sheets from said 
front side of said copier, the improvement comprising; bidirectional 
document drive means for bidirectionally feeding a large document with 
said large document sheet feeder, and control means for controlling said 
bidirectional document drive means in response to the input of documents 
and copying sheets such that a large document is initially fed in a first 
direction by said large document sheet feeder towards the rear of said 
copier, paused until a copy sheet is inputted from said front side of said 
copier, and then, in response to the inputting of a copy sheet, the same 
large document is next fed in a second, reversed, direction by said large 
document sheet feeder at a speed substantially higher than said sheet 
feeding copying velocity, and then, without pausing, the same large 
document is next again fed in said first direction by said large document 
sheet feeder, but at said sheet feeding copying velocity; and, wherein 
said control means controls said document drive means during said initial 
feeding in said first direction at a speed substantially higher than said 
sheet feeding copying velocity; and wherein said large document sheet 
feeder retains a large document inserted therein without substantial 
document slippage or skew until a selected number of copies is made from a 
document before releasing that document from said large document feeder. 
All references cited in this specification, and their references, are 
incorporated by reference herein where appropriate for appropriate 
teachings of additional or alternative details, features, and/or technical 
background.

Describing now in further detail the exemplary embodiment with reference to 
the Figures, there is shown an automatic xerographic reproduction or 
printing machine 8 for copying large documents, fed by constant velocity 
type document transport or feeder (CVT) 54. Machine 8 has a suitable frame 
or housing 10 within which its machine xerographic section 13 is 
operatively supported. The exemplary copier 8 may be, for example, a well 
known Xerox Corporation large document copier, or any other xerographic or 
other copier, as illustrated and described in various patents cited above, 
and other wise. As shown in FIG. 1, the processor or xerographic section 
13 thereof is supported by a stand 11 here. A document organizer 12 is 
attached to the frame 11, providing a document tray above the document 
sheet input 25 (see path A), and sloping down towards the front of the 
machine 8. The document organizer 12 may include a flip-card type of 
operator instruction manual 9. Also it is apertured as shown to provide a 
view therethrough of documents being fed rearwardly by the CVT 54. It also 
has front stop or catch fingers as illustrated. 
The control of all copier and document handler and finisher operations is 
by a machine controller 100. The controller 100 preferably and 
conventionally comprises a known type of programmable microprocessor 
system, as exemplified by extensive prior art, e.g., U.S. Pat. No. 
4,475,156 and its references. The particular desired functions and timings 
thereof are provided by conventional software programming of the 
controller 100 in non-volatile memory. The controller 100 controls all of 
the machine steps and functions described herein, including all sheet 
feeding. This includes the operations of the document feeder and its 
drives, document and copy sheet gates, copy sheet feeder drives, any 
finishes, etc. As further taught in those references, the controller 100 
also conventionally provides for storage and comparison of the counts of 
the copy and document sheets, the number of documents fed and 
recirculated, the desired number of copy sets, and other selections by the 
operator through a connecting panel of control switches. Controller 
information is utilized to control and keep track of the position of the 
document, the copy sheets, and the operative components of the apparatus 
by their electronic connections to the controller. For example, the 
controller may be conventionally connected to receive and act upon jam, 
timing, positional, and other control signals conventionally received from 
various document sheet sensors in the document path. The controller 
automatically actuates and regulates the positions of sheet path drives 
and gates depending upon which mode of operation is selected, and the 
status of copying in that mode. The controller 100 also conventionally 
operates and changes displays on a connecting instructional display panel, 
which preferably includes said operator function selection buttons or 
switches. 
Briefly, and as will already be familiar to those skilled in the art, the 
machine xerographic section 13 includes an image recording member, here a 
rotatable photoreceptor 14 comprising a drum having a photoconductive 
imaging surface 16. Operatively disposed about the path of imaging surface 
16 is a charge station 18 with charge corotron 19 for placing a uniform 
charge on the photoconductive surface 16, and exposure station 22 where 
the previously charged photoconductive surface 16 is exposed to light 
image rays from the document 9 being copied or reproduced, a development 
station 24 where the latent electrostatic image created on photoconductive 
surface 16 is developed by toner, a transfer station 28 with transfer and 
detack corotrons 29, 30 for transferring the developed image to a suitable 
copy substrate media or material such as a copy sheet 120 fed forward 
thereto in timed relation with the developed image on photoconductive 
surface 16, and a cleaning station 34 that may include a cleaning blade 
and a discharge corotron 36 for neutralizing residual charges and removing 
leftover developer from surface 16. 
Copy sheets 120 are brought forward to transfer station 28 by mating idler 
roll 160 and registration and drive roll 150, with sheet guides 42, 43 
serving to guide the sheet through an approximately 180.degree. turn prior 
to transfer station 28. Following transfer, the sheet 28 is carried 
forward to a fusing section 48 where the toner image is fixed by fusing 
roll 49. Fusing roller 49 is heated by a suitable heater such as lamp 47 
disposed within the interior of roll 49. In this exemplary fuser 48, the 
copy sheet is held by an opposing belt against the controlled temperature 
heated surface of roll 49. After fixing, the copy sheet is discharged. 
The illustrated CVT document handling system 54 provides for automatically 
transporting individual document sheets onto and over the conventional 
platen imaging station 50 of the copier 8 at an accurately predetermined 
steady velocity. Documents are inputted to the front or upstream end 
thereof via an input path 25. A narrow but full width transparent glass 
platen 50 preferably supports or confines the lower surface of the 
document as the document is moved past a scanning line 52 by the CVT 54, 
under a closely spaced white backing plate or foot 57 which confines the 
upper surface of the document there. As will be understood, scanning line 
52 extends across the width of platen 50 at a desired position where the 
document is to be optically scanned line by line as the document is 
uniformly moved at a constant copying speed over platen 50 by document 
transport 54. CVT transport 54 has input and output document feed roll 
pairs 55, 56, respectively, on each side of scanning line 52 for moving 
document 9 across platen 50 at the predetermined copying velocity or 
speed. An exposure lamp 58 is provided to illuminate a striplike area of 
platen 50 at scanning line 52. The image rays from the document line being 
scanned are transmitted by a gradient index fiber lens array 60 to 
exposure station 22 to expose the photoconductive surface 16 of the moving 
photoreceptor 14. For 1 to 1 copying (that is, equal size or 100% 
reduction/magnification copying), the velocity of the document at scanning 
line 52 is set equal to the velocity of surface 16 of the photoreceptor 
14. The photoreceptor 14 is conventionally driven at a constant speed by a 
conventional synchronous motor drive. 
These document feed roll pairs 55, 56 here are non-conventional, and are 
non-conventionally driven. Here, the CVT 54 drive is by a controller 
programmed controlled stepper motor drive 59 of the driving rollers, which 
are the lower rollers of the illustrated roller pair 55, 56 nips. These 
lower driving rollers are preferably a spaced plurality of accurately OD 
ground rubber rollers integrally mounted along a very rigid large diameter 
steel center shaft which is accurately rotatably mounted to the machine 
frame by ball bearings and rotatably driven by the stepper motor drive 59. 
This provides accurately planar, non-skewing, and non-wrinkling feeding 
nips for the document. The opposing, mating, idler rollers thereabove are 
resiliently deformably spring mounted to be deflectable upwardly by 
document passage through the nips, and preferably have some freedom of 
axial tilt as well, so as not to induce any skew on the document. As will 
be described further herein, here this stepper motor drive 59 of the CVT 
54 is reversible, with a higher reverse direction document driving speed. 
Conventional static eliminator brushes may be provided at the CVT 54 
output, which is towards the rear of the machine. 
Developing station 24 conventionally includes a developer housing 65, the 
lower part of which forms a sump 66, fed from a dispenser 67 of developer 
comprising a mixture of larger carrier particles and smaller toner or ink 
particles. A rotatable magnetic brush developer roll 68 is disposed in 
developer housing 65 in operative relation to the photoconductive surface 
16. Developer roll 68 brings toner from sump 66 into developing 
relationship with photoreceptor 14 to conventionally develop the latent 
electrostatic images formed on the photoconductive surface 16 from the 
document image exposure. 
The copy sheet handling system 100 here includes a humidity control storage 
chamber with an internal electrical heater for the large copy sheets 120. 
This comprises a copy sheet chamber 145, in which the copy sheets 120 to 
be fed are supported in stack-like fashion on a tray base 144. Extra 
sheets may be stored thereunder in tray base 143 for later use by 
placement onto base 144 for feeding. Heating of the chamber maintains 
dryness of the sheets as well as preventing curl from setting up in the 
sheets. 
Replenishment of copy sheets into copy sheet tray 145 is quick and easy for 
a number of reasons. First, the trays are tilted about 20 degrees with 
respect to a horizontal plane. This allows copy sheets to settle against 
the back of the copy sheet trays due to gravity while simultaneously 
inhibiting multifeeding. In loading a fresh supply of copy sheets into the 
chamber, cover 142 is opened and a stack of copy sheets are placed onto 
base 144 and cover 142 is closed. The positioning angle of the tray 144 
enhances the feeding of single copy sheets therefrom since gravity is 
being used to inhibit multifeeding. 
It will be appreciated that alternatively or optionally the copy sheet 
supply may be from a web roll. This may include a chopper cutter 
automatically cutting off a desired fed length of copy sheet to match the 
document sheet length, which can be measured automatically from the input 
feeding time of the document by the CVT 54 between actuation and 
deactuation of switch 51, for example. That is, the transit time from the 
initial document trail edge actuation of switch 51 and the start of 
feeding (or the lead edge actuation of switch 53 as feeding starts) until 
the release of switch 51 as the trail edge of the document passes it. See 
U.S. Pat. No. 4,823,663 for an example of a web roll feeder. 
For feeding a copy sheet 120 into the copy processor for copying, as 
described in the above-referenced copending applications, a simple feeding 
assist device may be provided to help the operator hand manipulate the 
topmost copy sheet on tray 144 out the front door 142 of chamber 145. The 
removed copy sheet is then hand manipulated via copy input path B into the 
nip of the stalled copy sheet input and registration roll pairs 150, 160, 
tripping switch 152 there. Registration roll pair 150, 160 then are driven 
to advance the copy sheet along a paper guide path to transfer station 28, 
registering the copy sheet with the image on the photoconductive surface 
16 of photoreceptor 15, by bringing the copy sheet into transfer relation 
with the developed image on photoconductive surface 16 at transfer station 
28. There, suitable transfer and detack means, such as transfer and detack 
corotrons 29, 30, transfer the toner image to the copy sheet and then 
separate the sheet for fixing the image in downstream fuser 48 and 
discharge as a finished copy sheet along copy output path B'. Copy output 
path B' here preferably includes a copy output stacking tray 170 (with an 
slide adjustable backstop 172 adjustable to the size of the copy media), 
into which the copy sheet may be directed as it is outputted. 
In operation, a document to be copied is first inserted by the operator 
into the front of the machine 8, via document input 25 in the path 
direction of arrow A. The document may be fed from a face-up stack of 
documents in the document organizer 12, if desired. The inserted document 
lead edge trips a switch 51 at the nip of the input or upstream rollers 
55. The document is then automatically fed in by the CVT 54, and it next 
actuates a second switch 53 in the downstream rollers 56 nip. The CVT 54 
advances the document downstream until it reaches a pause position, in 
which only the trailing edge of the document is in the CVT 54, held in the 
downstream rollers 56 nip. This is signaled and calculated from the 
release of switch 51 as the trail edge of the document passes that switch. 
At that document pause position the machine then stops, and waits for the 
insertion of a copy sheet. Note that the document was not copied in this 
step, unlike a normal large document copier. Thus, this initial step may 
be done with a much higher document feeding speed than is used for 
copying. Also note that in this position that the rest of the document is 
now in path A', at the rear of the machine 8, and none of it is 
obstructing the front of the machine. 
Due to gravity, the document will hang downwardly in path A'. A document 
catch tray 180 has a guide baffle extension portion 182 positioned to 
engage and guide a large document fed downstream by CVT 54 into this tray 
180. 
The copy sheet is then unobstructedly inserted into the nip of the 
registration roll 150, 160 as shown by arrow B, and released by the 
operator. This also actuates associated switch 152. In response to this 
and the operator actuation of the controller display "start print" or 
"copy" button, the microprocessor controller 100 then restarts the 
document sheet CVT drive 54 in the reverse direction, again without 
copying, and at a much higher speed than the document copying speed. This 
briefly feeds the entire document out to the front of the machine again 
(reversing path A), but only temporarily, and only until the document lead 
edge is back in the upstream or input nip of rollers 55, in a position for 
start of scan. Then the document and copy sheet are both automatically 
driven in synchronism with one another, at the copying speed, with the 
document traveling into the machine in the direction of arrow A and the 
copy sheet traveling into the machine in the direction of arrow B. 
This process may then be repeated for the number of copies required and/or 
set into the control 100 by conventional operator display buttons. 
However, with this system, the document does not need to be initially 
reloaded for subsequent copies. The document remains held in at least one 
nip of the CVT 54 at all time until all the selected number of copies 
thereof are made. 
After the selected number of copies are made of the document, the document 
is automatically ejected via path A' into tray 180, up to front stop 
fingers 184. This tray 180 need not be as long as the document. After the 
trail edge of the document is released by the rollers 56 nips, a trail end 
portion of the document may be allowed to fall and overhang the rear end 
of the tray 180 as shown by document path A". 
Note that this document tray 180 is front accessible for operator front 
unloading. So are all the other trays of this copying machine. Also, all 
of the disclosed document and copy trays 12, 180, 170, 144 and 143 here 
are respectively superposed, overlying one another, and the copier 
processor 10, to provide a compact machine. 
While the embodiment disclosed herein is preferred, it will be appreciated 
from this teaching that various alternatives, modifications, variations or 
improvements therein may be made by those skilled in the art, which are 
intended to be encompassed by the following claims.