Full productivity high performance inverter

A full productivity, high performance inverter apparatus includes a sheet input nip, a sheet output nip, a reversing roll nip downstream of the input and output nips, and adjustable interleaving baffles for guiding sheets of a wide variety of lengths between the input nip, output nip, and the reversing nip.

BACKGROUND OF THE INVENTION 
This invention relates to an apparatus for turning over and exchanging lead 
and trail edges of sheets, and more particularly, to an improved full 
productivity high performance inverter apparatus that is adjustable in 
size to accommodate different sheet lengths. 
Although a sheet inverter is referred to in the copier/printer art as an 
"inverter", its function is not necessarily to immediately turn the sheet 
over (i.e., exchange one face for the other). Its function is to 
effectively reverse the sheet orientation in its direction of motion. That 
is, to reverse the lead and trail edge orientation of the sheet. 
Typically, in inverters as disclosed here, the sheet is driven or fed by 
feed rollers or other suitable sheet driving mechanisms into a sheet 
reversing chute. By then reversing the motion of the sheet within the 
chute and feeding it back out from the chute, the desired reversal of the 
leading and trailing edges of the sheet in the sheet path is accomplished. 
Depending on the location and orientation of the inverter in a particular 
sheet path, this may or may not also accomplish the inversion (turning 
over) of the sheet. In some applications, for example, where the 
"inverter" is located at the corner of a 90.degree. to 180.degree. 
inherent bend in the copy sheet path, the inverter may be used to actually 
prevent inverting of a sheet at that point, i.e., to maintain the same 
side of the sheet face-up before and after this bend in the sheet path. On 
the other hand, if the entering and departing path of the sheet, to and 
from the inverter, is in substantially the same plane, the sheet will be 
inverted by the inverter. Thus, inverters have numerous applications in 
the handling of either original documents or copy sheets to either 
maintain or change the sheet orientation. 
In the field of reprographic machines, depending on the architecture, the 
finisher setup, and paper path configuration, some simplex printing may 
require an inverter subsystem in order to deliver copy sheets in 1- N 
orientation when the sheets are removed from an output tray. One prior art 
inverter for accomplishing this task is shown in FIG. 1. which shows the 
conventional configuration of a reversing roll inverter. In order to 
minimize the straight through (non-inverting) paper path length and to 
handle sheet sizes from B5 to A3 (sheet lengths: 7" to 17"), this inverter 
may require the copier/printer to operate in a skip-pitch mode for sheets 
larger than A4 sizes. This impacts significantly the throughput of larger 
sheets that require inversion. 
The present invention aims at providing an adjustable baffle reversing roll 
inverter which can adapt to all sheet sizes to maintain full machine 
productivity. Baffles of the inverter are interleaved so that they can 
easily be extended or collapsed to accommodate sheets of different 
lengths. 
SUMMARY OF THE INVENTION 
Accordingly, the present invention provides a sheet inverter device having 
an input nip for feeding sheets into a reversing roll nip and an output 
nip for receiving the sheets from the reversing roll nip and feeding the 
sheets out of the inverter device. An improvement of the inverter device 
includes an adjustable chute positioned between the input and output nips 
and the reversing roll which enables full productivity, and high 
performance of the inverter device. The adjustable chute has a stationary 
portion and a slidable portion with the slidable portion being movable in 
parallel with respect to the stationary portion in order to adjust the 
length of the adjustable chute to accommodate a wide variety of sheet 
lengths and thereby maintain full machine productivity.

DETAILED DESCRIPTION OF THE INVENTION 
The invention will now be described by reference to a preferred embodiment 
of the inverter system of the present invention for a copier/printer. 
However, it should be understood that the sheet inverting method and 
apparatus of the present invention could be used with any machine in which 
inversion of a sheet is desired, be that sheet stacking or duplexing. 
In general, an improvement to prior sheet inverter systems of machines is 
disclosed which is cost effective and comprises the use of collapsible 
baffles in inverting sheets. 
The prior art apparatus shown in FIG. 1 consists basically of means for 
holding a stack 2 of copy sheets adjacent to a feeder 4 for extracting a 
sheet from the top of the stack each time a copy is required. Each sheet 
leaving feeder 4 passes in non-sliding contact with a photoreceptor 6 
(shown here in the form of a drum, although it could equally be a belt), 
from which a particulate material (toner) designed to present a visual 
contrast with the material of the sheet is transferred from the surface of 
the photoreceptor to the upper face of the respective sheet 41. After the 
sheet with the toner image held on it by electrostatic attraction has been 
detached from the photoreceptor 6, it is conveyed by a conveyor 8 to a 
fuser 10, which fuses the toner into a permanent bond with the material 
forming the sheet, by the application of heat and/or pressure. 
On leaving the fuser, the sheet is captured by idler roll 25 and drive roll 
26 and is either driven through the top of the inverter 20 into a nip 
formed between idler roll 27 and drive roll 28 which drives the sheet into 
catch tray 18 or contacts an inverter selection gate 11, if inversion is 
required, which deflects the sheet down an inclined chute 12 into 
reversing roll nip 30. An inverter gate 22 closes off chute 12 once the 
trail edge of a sheet has passed it and prevents the sheet from being 
driven back into chute 12 by reversing roll 30. The natural resilience of 
the sheet material is used to flip the freed trail edge of the sheet to 
the right as viewed, making it immediately clear the pointed end of the 
structure supporting inverter gate 22 which, at this time, will have been 
flipped to the left to close off chute 12. Reversing roll nip 30 drives 
the sheet up inclined chute 13 into a nip formed between idler roll 27 and 
drive roll 28 which drives the sheet into sheet transport nip 16 for 
conveying to catch tray 18. 
Inverter 40 of the present invention in FIG. 2, comprises an idler roll 43 
that forms an incoming sheet driving nip with drive roll 44 and is driven 
in the direction of arrow 72 by drive roll 44 to drive sheets into 
inverter 40. An outgoing nip for driving sheets out of the inverter is 
formed between idler roll 45 and drive roll 46. Idler roll 45 of the 
outgoing nip is driven by drive roll 46 with the nip formed therebetween 
driving sheets into catch tray 18. Inverter selection gate 47 is 
positioned downstream of the incoming nip and is controlled by controller 
60 to intercept a copy sheet and divert it into the inverter or not 
intercept a sheet and allow the sheet to pass straight through the 
inverter and be driven out of the inverter by the outgoing nip towards 
catch tray 18. 
Inverter 40 includes an interdigitated leaving, collapsible, adjustable 
baffle arrangement that forms a chute for incoming and outgoing sheets and 
comprises a stationary portion 81 and a movable or slidable portion 86 
with the slidable portion 86 being adjustable in the directions of arrow 
89 by controller 60 in accordance with the length of copy sheets on which 
copies are to be made. A reversing roll nip 49 is positioned to receive 
incoming sheets and drive them into the outgoing nip formed between idler 
roll 45 and drive roll 46. An inverter gate 42 is adapted to be moved by 
controller 60 away from the path of incoming sheets and moved into the 
incoming sheet path after each sheet passes it in order to prevent a sheet 
from being driven back into the incoming sheet path by reversing roll nip 
49. Slidable baffle portion 86 and reversing roll nip 49 are preferably 
mounted on a conventional carriage (not shown) that is driven by a stepper 
motor upon actuation by a signal from controller 60 in either direction of 
arrow 89. It should be understood that any desired conventional mechanical 
means for moving or sliding the baffle portion 86 and reversing roll nip 
can be used., e.g., a rack and pinion mechanism. 
When the inversion option is selected, adjustable baffle portion 86 is 
moved into a predetermined position according to the length of the sheets 
by controller 60 while a copy sheet 41 exiting the fuser 10 enters the 
inverter 40 lead edge first. The sheet 41 is advanced by the incoming nip 
formed between idler roll 43 and feed roll 44. Inverter selection gate 47 
is actuated by controller 60 to intercept the sheet and divert it down 
into the inverter chute while it is still under the driving influence of 
the incoming nip. After the trail edge of the sheet passes inverter gate 
42, which is in a closed position and out of the path of the sheet, 
inverter gate 42 is actuated to block return of the sheet to the incoming 
sheet path. The sheet is captured and driven further into the inverter by 
reversing roll nip 49. Once the trail edge of the sheet is sensed by 
sensor 48, reversing roll nip 49 reverses its direction of rotation and 
drives the sheet into the outgoing nip formed between idler roll 45 and 
drive roll 46. The outgoing nip in turn drives the sheet into sheet 
transporting nip 16 that conveys the sheet to catch tray 18. 
Inverter 40 has several advantages over prior inverters in that: it is 
compact by employing a short paper path for simplex copying; it enables 
full productivity; it has high reliability due to its lower roll and sheet 
acceleration and deceleration; and less power is required to invert 
sheets. 
As described above in detail, the adjustable baffle reversing roll inverter 
of the present invention is adaptable to all sheet sizes to maintain full 
machine productivity. The baffles are interleaved so that they can easily 
be extended or collapsed to accommodate sheets of different lengths. The 
inverter assembly is mounted on a carriage which is configured to slide in 
and out or up and down depending of the size of copy sheets being used. 
It is, therefore, evident that there has been provided in accordance with 
the present invention an inverter apparatus for copiers/printers or the 
like which serves to turn over as well as reverse lead and trail edges of 
sheets thereby fully satisfying the aims and advantages hereinbefore set 
forth. While this invention has been described in conjunction with a 
specific embodiment thereof, it is evident that many alternatives, 
modifications and variations will be apparent to those skilled in the art. 
Accordingly, it is intended to embrace all such alternatives, 
modifications and variations as fall within the spirit and broad scope of 
the appended claims.