Set transport

A set transport including a direction changing device is disclosed which includes a sun roll 76, arcuate guide means 80, 81 around the sun roll 76 and a plurality of spaced planet rolls 77, 78, 79 which coact with the sun roll 76. The planet rolls are driven faster than the sun roll. Preferably the sun roll 76 has a rigid surface and the planet rolls have compliant surfaces and form an interference relationship with the sun roll.

This invention relates to a set transport for conveying sets of sheets and 
particularly for conveying sets of sheets around a turn path to change 
their direction of movement. The invention also relates to copy finishing 
apparatus incorporating such a set transport. 
According to the present invention the transport includes a direction 
changing device comprising a relatively large transport roll, arcuate 
guide means around said roll, a plurality of spaced circumferentially 
rolls coacting with said roll, and means for driving said transport roll 
and spaced rolls so that the surface speed of said spaced rolls is greater 
than the surface speed of the transport roll. 
Preferably the surface speeds of the spaced rolls are approximately 10% to 
30% greater than that of the transport roll. Different spaced rolls may 
have different speeds. 
In a preferred form the transport roll has a rigid surface and the spaced 
rolls have compliant surfaces, the latter being formed for example of foam 
material. 
While intended for handling sets of sheets, whether bound together or not, 
a transport according to the invention may also be capable of conveying 
single sheets and to this end the spaced rolls preferably form an 
interference relationship with the transport roll. For example foam spaced 
rolls may interfere with the transport roll by about 2.+-.1 mm. 
The direction changing device may be arranged for reversing the direction 
of a set, at the same time inverting the set, for example for conveying 
sheets between first and second superposed support surfaces. Such a device 
may have circumferentially spaced planet rolls. 
The invention also provides a finisher including a first support surface 
for compiling a set of sheets serially delivered thereto, means for 
binding a said set, a second support surface, and a set transport as 
described above for conveying a set from said first support surface to 
said second support surface.

Referring first to FIG. 1 there is shown a xerographic copying machine 
incorporating a recirculating document handler 40 and a finisher 60 
according to the present invention. The machine includes a photoreceptor 
drum 1 mounted for rotation (in the clockwise direction as seen in FIG. 1) 
to carry the photoconductive imaging surface of the drum sequentially 
through a series of xerographic processing stations: a charging station 2, 
an imaging station 3, a development station 4, a transfer station 5, and a 
cleaning station 6. 
The charging station 2 comprises a corotron which deposits a uniform 
electrostatic charge on the photoreceptor. A document to be reproduced is 
positioned on a platen 13 and scanned by means of a moving optical 
scanning system to produce a flowing light image on the drum at 3. The 
optical image selectively discharges the photoconductor in image 
configuration, whereby an electrostatic latent image of the object is laid 
down on the drum surface. At the development station 4, the electrostatic 
latent image is developed into visible form by bringing into contact with 
it toner particles which deposit on the charged areas of the 
photoreceptor. Cut sheets of paper are moved into the transfer station 5 
in synchronous relation with the image on the drum surface and the 
developed image is transferred to a copy sheet at the transfer station 5, 
where a transfer corotron 7 provides an electric field to assist in the 
transfer of the toner particles thereto. The copy sheet is then stripped 
from the drum 1, the detachment being assisted by the electric field 
provided by an a.c. de-tack corotron 8. The copy sheet carrying the 
developed image is then carried by a transport belt system 9 to a fusing 
station 10. 
After transfer of the developed image from the drum, some toner particles 
usually remain on the drum, and these are removed at the cleaning station 
6. After cleaning, any electrostatic charges remaining on the drum are 
removed by an a.c. erase corotron 11. The photoreceptor is then ready to 
be charged again by the charging corotron 2, as the first step in the next 
copy cycle. 
The optical image at imaging station 3 is formed by optical system 12. A 
document (not shown) to be copied is placed on platen 13 by the document 
handler 40, and is illuminated by a lamp 14 that is mounted on a scanning 
carriage which also carries a mirror 16. Mirror 16 is the full-rate 
scanning mirror of a full and half-rate scanning system. The full-rate 
mirror 16 reflects an image of a strip of the document to be copied onto 
the half-rate scanning mirror 17. The image is focussed by a lens 18 onto 
the drum 1, being deflected by a fixed mirror 19. In operation, the 
full-rate mirror 16 and lamp 14 are moved across the machine at a constant 
speed, while at the same time the half-rate mirrors 17 are moved in the 
same direction at half that speed. At the end of a scan, the mirrors are 
in the position shown in a broken outline at the left hand side of FIG. 1. 
These movements of the mirrors maintain a constant optical path length, so 
as to maintain the image on the drum in sharp focus throughout the scan. 
Alternatively the optical system 12 may be fixed in position and the 
document scanned by being advanced across it by the document handler 40 as 
described below. 
At the development station 4, a magnetic brush developer system 20 develops 
the electrostatic latent image. Toner is dispensed from a hopper 21 by 
means of a rotating foam roll dispenser 22, into developer housing 23. 
Housing 23 contains a two-component developer mixture comprising a 
magnetically attractable carrier and the toner, which is brought into 
developing engagement with drum 1 by a two-roller magnetic brush 
developing arrangement 24. 
The developed image is transferred, at transfer station 5, from the drum to 
a sheet of copy paper (not shown) which is delivered into contact with the 
drum by means of a paper supply system 25. Paper copy sheets are stored in 
two paper trays, an upper, main tray 26 and a lower, auxiliary tray 27. 
The top sheet of paper in either one of the trays is brought, as required, 
into feeding engagement with a common, fixed position, sheet 
separator/feeder 28. Sheet feeder 28 feeds sheets around curved guide 29 
for registration at a registration point 30. Once registered, the sheet is 
fed into contact with the drum in synchronous relation to the image so as 
to receive the image at transfer station 5. 
The copy sheet carrying the transferred image is transported, by means of 
vacuum transport belt 9, to fuser 10, which is a heated roll fuser. The 
image is fixed to the copy sheet by the heat and pressure in the nip 
between the two rolls of the fuser. The final copy is fed by the fuser 
rolls along output guides 31 to the input nip 65 of the finisher 60. 
After transfer of the developed image from the drum to the copy sheet, the 
drum surface is cleaned at cleaning station 6. At the cleaning station, a 
housing 33 forms with the drum 1 an enclosed cavity, within which is 
mounted a doctor blade 34. Doctor blade 34 scrapes residual toner 
particles off the drum, and the scraped-off particles then fall into the 
bottom of the housing, from where they are removed by an auger. 
As mentioned above, sheets 5 may be fed from either the main tray 26 or the 
auxiliary tray 27. The auxiliary tray is of larger size than the main 
tray, enabling a wide choice of paper sizes and types to be fed from it. 
The trays are physically located in the lower part of the machine below 
the photoreceptor drum 1. 
As shown in FIG. 1 a recirculation document handler 40 is provided for 
feeding documents to be copied to the platen 13 of the photocopier. The 
document handler includes a storage tray 41 for the documents to be copied 
and document circulating means for delivering the documents in turn to the 
platen from the storage tray and for returning the documents to the tray, 
whereby the documents may be circulated and recirculated in sequence past 
the platen for repeated copying (precollation mode). The documents may 
either be transported across the platen at a constant velocity past the 
optical system 12 of the photocopier which is held stationary in the solid 
line position shown, or instead they may be registered on the platen prior 
to copying and the stationary document exposed by scanning the optical 
system 12 across the document as described above. For this purpose a 
registration member or gate 39, which can be moved in and out of sheet 
blocking position at the registration edge of the platen by means of a 
conventional solenoid type actuator, is provided for registering the 
document in stationary position on the platen 13 while the optical system 
12 is scanned across the document. When the document is registered on the 
platen, the document handler can be operated in so-called stacks mode 
wherein each document is copied a plural number of times during a single 
delivery to the platen. 
The document handler comprises, in addition to the storage tray 41, a 
document separator/feeder 42, a pre-platen transport 43 for conveying 
documents to the platen, a platen transport 44 and a post-platen transport 
45 by which documents are returned to the storage tray. 
The document storage tray 41 is mounted over the platen 13 and slopes 
upwardly towards the separator/feeder 42; it is adjustable to accommodate 
different document sizes. 
Sheet separation and acquisition is accomplished by a vacuum belt 
corrugation feeder (VCF) 42 using flotation pressure differences between 
the bottom sheet and the sheets above, sheet corrugation and vacuum, a 
parabolic contour pocket being cut out at the lead edge of the tray 41 and 
dished down in the manner shown and described in U.S. Pat. No. 4,275,877. 
Documents placed in the tray, bridge this gap and form a flotation pocket. 
Transport belts 46 surface through the document tray within the contour 
pocket. Document stack flotation is accomplished by a frontal assault of 
air from an air knife 47. The air jet impinges on the tray just in front 
of the lead edge of the document stack; this permits volumetric flow 
expansion of air within the pocket contour of the tray and also riffles 
the front edge of the documents to allow a differential pocket of air 
between the bottom sheet and sheet 2. This assists in the acquisition, 
separation and feeding of the bottom document. 
The pre-platen and post-platen transports 43,44 consist of pairs of nip 
rolls and inner and outer inversion guides as shown and the platen 
transport 45 comprises a single white, wide friction drive belt 48 
entrained over input and output transport rollers 49. The document is 
transported across the platen 3 by the belt 48. Three gravity rolls apply 
a nip between the belt 48 and platen 13 and maintain drive across the 
platen. 
The document handler may be operated as described above either in 
pre-collation (or sets) mode in which the pages of a document are copied 
one at a time in serial number order or in post-collation (or stacks) mode 
in which multiple copies of each document sheet are made before the next 
document sheet is copied. In accordance with the invention a copy sheet 
finishing apparatus 60 capable of handling output for the document handler 
in both these modes is shown in FIG. 1. 
The finisher 60 includes an offsetting catch tray or output tray 100 and 
may be operated to perform the following functions: 
(a) to compile, register and corner staple sets of copies as they are 
produced and transport the stapled sets into the offsetting catch tray 
100, and 
(b) to deliver copies direct to the offsetting catch tray 100 where the 
sheets may be compiled in offset sets. 
In a variation of (a) the stapling step may be omitted. 
The finisher receives copy sheets from the processor at input nip 65 and 
conveys them to the offsetting catch tray 100 either directly along a path 
61 or, via a compiler tray 62 in which they are registered and stapled, 
along a path 63. The direction of the sheets is determined by a diverter 
64 located directly following the finisher input nip rolls 65a, 65b and 
which is operated in response to a signal from the processor initiated by 
the operator. 
The path 63 comprises upper and lower guides 63a, 63b and includes two 
further sets of nip rolls 67, 68 which accelerate the sheets into the 
compiler tray 62. The sheets are corner registered against a retractable 
end registration gate 69 and a side registration gate 70 at the front of 
the machine by gravity and a paddle wheel 71, represented in FIG. 1 by a 
broken ellipse. Sets compiled in the tray 62 are corner stapled by a 
stapler 72. Stapled sets are driven from the tray 62 by retracting the 
gate 69 and lifting the set against a pair of driven eject rolls 73 by 
means of a pair of idler rolls 74 mounted on one end of pivoted arm 75 
which carries the gate 69 at its other end. 
Thus the sheets are conveyed into the compiler tray in a first direction 
(from right to left in FIG. 1) and their trail edges registered by being 
conveyed against the end registration gate 69 in the opposite direction 
(from left to right in FIG. 1). The path 63 extends over the paddle wheel 
71 and the eject rolls 73 and the sheets drop by gravity towards the end 
registration gate 70 since the tray 62 slopes downwardly in that direction 
at an angle of between 35 and 45 degrees. In the embodiment of FIG. 1 the 
angle is 38 to 42 degrees, preferably 40 degrees. Essentially the tray 
angle must be sufficient for the sheeets to drop by gravity into the 
influence of the paddle wheel 71. 
The sets are carried into the offsetting catch tray 100, which is arranged 
beneath the compiler tray 62, around a large driven, rigid transport roll 
76 with the aid of three smaller driven, compliant rolls 77, 78, 79 and 
outer guides 80, 81. Thus as the sets are conveyed to the offsetting catch 
tray 100 they are inverted and their direction reversed. The catch tray 
100 itself slopes downwardly in the same direction as the compiler tray 62 
suitably at an angle of 35 to 40 degrees, preferably 40 degrees. 
In sets copying mode, a document set to be copied is placed face up in the 
document handler tray 41 so that the pages of the document are copied in 
reverse order. Thus, copy sheets are delivered to the compiler tray of the 
finisher in the order n-1. The copy sheets are received face-up so that 
the assembled set is in page number order and are fed through the copier 
long edge first so that the top of the page is at the front side of the 
machine. Accordingly the top left-hand corner of the set is arranged in 
the registration corner and is stapled. Thus sets stapled in the compiler 
tray 62 are received face-down in the catch tray 100 with the stapled 
corner at the upper front of the tray. 
The above-described configuration provides a compact finisher in which the 
extent to which the finisher projects beyond the processor is kept to a 
minimum. At the same time it permits sheets which do not need to be 
stapled to be fed directly to the catch tray 100. 
Thus, where stapling is not required sheets are directed along path 62 into 
engagement with the roller 76 and driven into the tray 100 with the aid of 
driven foam rolls 78, 79. The tray 100 may be offset sideways between sets 
to provide visual and physical separation between the sets. 
The finisher 60 will now be described in greater detail. 
Sheets from the fuser 10 of the processor enter the finisher through the 
input nip rolls 65 which comprise a low steel roll 65b incorporating a 
one-way or overrun clutch with a pair of rubber bands thereon and a pair 
of upper idler acetal rolls 65a. Drive to the lower rolls 65b (and to all 
driven rolls of the finisher) is from the processor output spur gear (not 
shown). The rolls 65 assist in driving the copies to the diverter 64, and 
beyond. The diverter 64 extends across the paper path and has the 
cross-section shown in FIG. 1. It is operated by a solenoid 91 (FIG. 4) 
through a linkage 92. The solenoid is energised to direct sheets along 
path 63 into the compiler 62. 
The upper transport path 63 comprises upper and lower sheet metal guides 
63a, 63b and the two further sets of nip rolls 67, 68. These comprise 
upper idler acetal rolls 67a, 68a and lower driven polyurethane rolls 67b, 
68b. In order to project the sheets positively onto the compiler tray 62, 
over the paddle wheel 71 and eject roll 73, the nip rolls 67, 68 are 
driven at a faster rate than the rolls 65. The one-way clutch in the lower 
roll 65b prevents the copies from being torn or scrubbed. The idler rolls 
67a, 68a as well as the input idler rolls 65a are mounted on the upper 
guide plate 63a which is hinged from the back of the finisher for jam 
access. The nip roll sets 65, 67, 68 serve to corrugate the copy sheets 
and the idlers are fixed to the plate 63a by snap-on flexures. 
On reaching the compiler tray 62 the copy sheets are reverse corner 
registered against end registration stops 69 and side registration plate 
70 at the front of the machine by a driven 3-bladed paddle wheel 71 (FIGS. 
2 and 6). The paddle wheel is straight-bladed and is made of polyurethane. 
For improved registration the blades flip down on to the sheets from a 
restraining plate 71a. 
The stapler 72 is arranged over the registration corner as shown in FIG. 6 
to insert a staple through that corner of the set. The stapler is actuated 
when the processor logic detects that a complete set has been delivered to 
the compiler tray 62. The stapler inserts staples at an angle of 
20.degree. to the long edge of the set. 
Referring to FIGS. 7 to 10, the stapler 72 is a standard desk top stapler 
with a conventional head 101 and passive clincher (not shown). It has a 
capacity of 160 staples and can staple up to 25.times.80 gm. sheets. Drive 
to the stapler is by a motorised cam 103, a cam lever 104, a staple head 
lever 105 and a connecting shaft 106. This arrangement allows the cam 
drive to be positioned at the rear of the machine although the stapler is 
at the front. Adjustment for the staple head lever position is provided by 
a knuckle joint in the cam lever 104. The stapler is driven by a separate 
AC motor/gearbox 107 (FIG. 7). 
A load limiting device is incorporated into the cam lever 104 to (a) 
accommodate varying set thicknesses presented to the stapler and (b) 
enable the cam 103 to rotate in the event of seizure or staple jam. This 
device comprises a bracket 108 pivoted to the cam lever 104 and connected 
to it through a compression spring 109. The cam follower 103a is mounted 
on the bracket 108 and relative movement of the bracket 108 and lever 104 
limits the force applied by the staple head lever. Thus, if the staple 
head is closed before the cam 103 has completed its cycle, excess movement 
is absorbed by the cam lever bracket 108 as shown in FIG. 10. The load 
limiting spring 109 prevents the bracket 108 from pivoting prematurely. 
Located just above the back edge of the cam lever bracket 108 is a 
micro-switch 110. As the lever/bracket assembly moves up and down 
electrical continuity through the microswitch is interrupted. This signal 
is used to monitor cam rotation and may assist in staple jam detection. 
Return of the stapler head to an open position after each stapling 
operation is assisted by a spring 111 attached between the bracket 108 and 
the finisher frame and a spring integral with the stapler head. 
Staple levels in the magazine are monitored by a low staple sensor (not 
shown) activated when only twenty four staples remain. This sensor is an 
optical sensor consisting of an infra-red source and a detector aligned 
with holes through the staple rail. A signal from the sensor allows the 
processor logic to assess how many sets are outstanding against the 
ongoing job and act accordingly. 
A solenoid 114 (FIG. 2) mounted under the compiler tray 62 acts on pivoted 
arm 75 which as shown in FIGS. 11 to 13 comprises levers 112 and 113. 
Lever 112 is attached to gate 69 and through an intermediate lever 112a 
operates a lever 113 carrying the eject (kick-out) idler rolls 74. During 
compiling and stapling the rolls 74 and gate 69 are as shown in FIG. 11. 
Once the stapling operation has been completed, the solenoid is energised 
to pivot the levers 112, 113 as shown in FIG. 12, retracting the gate 69 
and lifting rolls 74 through a cut-out 62a in the compiler tray to nip the 
set against continuously driven rolls 73 and drive the set out of the 
compiler tray. 
The rolls 73 and 74 each comprise a spaced pair of grooved rolls with 
O-ring inserts. The idlers 74 are spaced slightly further apart than the 
driven rolls 73. 
Stapled sets are transported to the catch tray 100 around transport roll 76 
which is 70 mm wide and 135 mm in diameter. It has a rigid hub of a 
thermoplastic resin material, suitably a modified polyphenylene oxide such 
as Noryl, with a high friction polyurethane coating. Suitably the surface 
of roll 76 has a hardness of 60.+-.5 IRHD. Transport of the sets around 
roll 76 is aided by the compliant rolls 77, 78, 79 and the guides 80, 81. 
The rolls 77, 78, 79 are foam rolls 30 mm in diameter and having a 10 mm 
thick layer of foam over a rigid hub. The foam material is a polyurethane 
ester suitably having a cell size of 18 cells per linear centimeter. The 
rolls 77, 78, 79 are driven at a slightly greater speed (about 10% or more 
faster) than the roll 76 to compensate for the difference in speed between 
the inner and outer surfaces of a set being transported. In one embodiment 
in which the rolls have the dimensions above the roll 76 is driven at a 
surface speed of 307 mm/sec and the rolls 77, 78, 79 are respectively 
driven at surface speeds of 353 mm/sec (15%), 402 mm/sec (31%) and 335 
mm/sec (9%), the percentages in parenthesis indicating the amount by which 
the speed of the roll 76 is exceeded. The guide 81 can be hinged down for 
jam access. 
With the diverter solenoid 91 not energised, the diverter 64 is kept raised 
by a compression spring around the solenoid plunger and sheets are 
directed along the path 61 directly to the eject roll 76 and the catch 
tray 100. 
The transport roll 76, like the nip rolls 67, 68, accelerates copies from 
the input rolls 65 to minimise set delivery time. 
The offsetting catch tray 100 (FIG. 14) provides physical and visual 
distinction between consecutive sets and this is achieved by reciprocating 
the tray through 35 mm. The tray is driven by a separate DC motor/gearbox 
through a cylindrical cam 121 and follower 121a. The tray slopes upwardly 
at a relatively steep angle and has an upstanding rear registration edge 
126. The tray is slideably mounted on stub shafts 122 carried on the 
finisher cover by means of brackets 123. Reaction studs 124 on the tray 
edge 126 ride on PTFE strips fixed to the outside of the cover The catch 
tray is activated by a sensor switch 127 (FIG. 12) in the lower part of 
the set transport. 
A spring loaded rib 11/2-2" wide extends downwardly along the tray to 
maintain uniform drop height into the tray as the sheets build up. Mylar 
control strips (not shown) hang from the cover above the tray to help 
guide paper onto the tray. 
The finisher drives are shown in FIGS. 3 and 15. A spur gear 131 takes the 
drive from the processor and apart from the roll 65b which is driven 
directly from the spur gear 131 all driven rollers and the paddle wheel 
are driven via toothed belts 132, 133 and spur gears 134, 135. The latter 
are all arranged at the back of the finisher behind the rear frame 142 as 
shown in FIG. 3. Front and rear frames 141, 142 moulded in plastic support 
all finisher components. The two frames are separated structurally by two 
steel tie bars, the lower plate 63b of upper transport guide 63 and the 
compiler tray (sheet steel). 
The finisher and its covers are mounted separately. As shown in FIGS. 2 and 
3, downwardly facing U-mountings of the frames 141, 142 sit on docking 
studs 143, 144 projecting from the processor frame and the assembly is 
held in position by gravity. The cover is held in place by four latch 
mechanisms, two front and two rear, which locate on docking studs fixed to 
the processor frames. The rear latches are secured by locking screws. 
In operation sheets are either delivered to the compiler tray 62 along the 
upper path 63 or fed directly to the offsetting catch tray 100 along the 
path 61. In the latter case the sheets may be stacked in offset sets by 
intermittently side-shifting the tray 100 under the control of the machine 
logic. Sheets delivered to the compiler tray 62 are reverse registered by 
gravity and the paddle wheel 71 against registration stops 69, 70. When 
all the sheets in a set have been received in the tray 62, the machine 
logic activates the motor 107 to cause the stapler 72 to insert a staple 
in the set and then activates the solenoid 114 to cause the gate 69 to 
retract and the eject rolls 73, 74 to engage the set to drive the set out 
of the tray to the direction reversing transport formed by the transport 
roll 76 and its associated smaller rolls and guides. The transport conveys 
the set into the offsetting catch tray 100 where successive sets are 
stacked for collection by an operator. The catch tray may be offset 
between sets. 
The compiler tray will not accept more than 25 sheets. If the finisher is 
in binding mode and a sensor (not shown) in the path 63 has counted 25 
sheets, it will direct the twenty-sixth and subsequent sheets directly to 
the catch tray 100 and also eject the stack of sheets in the tray 62 into 
the tray 100 without binding them. 
Although specific embodiments have been described, it will be understood 
that various modifications may be made without departing from the scope of 
the invention as defined in the appended claims. For example, while a 
paddle wheel registration device is described and illustrated any suitable 
form of sheet registration device may be employed.