U.S. patent application number 10/456809 was filed with the patent office on 2004-12-09 for printer sheet vacuum transport curled sheets acquisition.
This patent application is currently assigned to Xerox Corporation. Invention is credited to Domoto, Gerald A., Lohr, S. Warren, Panides, Elias.
Application Number | 20040245711 10/456809 |
Document ID | / |
Family ID | 33490239 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040245711 |
Kind Code |
A1 |
Domoto, Gerald A. ; et
al. |
December 9, 2004 |
Printer sheet vacuum transport curled sheets acquisition
Abstract
The transporting of flimsy print media sheets having curled
sheet edges being fed from a fuser or other input onto a vacuum
sheet transport belt system is provided with improved acquisition
by simultaneously blowing the upper surface of the sheet's curled
lead edge area down towards the vacuum belt transport with a
positive pressure airflow while the vacuum sheet transport is
attracting the sheet with its an underlying vacuum manifold
airflow. Both the vacuum manifold airflow and the positive pressure
airflow may be respectively provided solely by the air intake and
the air exhaust from a single blower. The positive pressure airflow
may be provided from a manifold extending transversely over at
least the upstream end of the vacuum belt transport, spaced
therefrom, and feeding air to one or more air jets.
Inventors: |
Domoto, Gerald A.;
(Briarcliff Manor, NY) ; Lohr, S. Warren; (Sleepy
Hollow, NY) ; Panides, Elias; (Whitestone,
NY) |
Correspondence
Address: |
PATENT DOCUMENTATION CENTER
XEROX CORPORATION
100 CLINTON AVE., SOUTH, XEROX SQUARE, 20TH FLOOR
ROCHESTER
NY
14644
US
|
Assignee: |
Xerox Corporation
|
Family ID: |
33490239 |
Appl. No.: |
10/456809 |
Filed: |
June 6, 2003 |
Current U.S.
Class: |
271/197 |
Current CPC
Class: |
G03G 15/6573 20130101;
B65H 2406/364 20130101; G03G 15/6529 20130101; B65H 2301/4461
20130101; B65H 2406/12 20130101; B65H 29/242 20130101 |
Class at
Publication: |
271/197 |
International
Class: |
B65H 029/32 |
Claims
What is claimed is:
1. In a sheet transport system with a sheet feeding path for
transporting flimsy print media sheets having upper and lower
surfaces, at lease some of which flimsy print media sheets in said
sheet transport system are curled, said sheet transport system
including at least one vacuum sheet transport system and at least
one non-vacuum sheet transport system; wherein said vacuum sheet
transport system has a vacuum blower providing a vacuum airflow to
said vacuum sheet transport system for providing vacuum attraction
of the lower surface of said sheets against said vacuum sheet
transport system, and wherein said vacuum blower has a positive air
pressure exhaust airflow output corresponding to said vacuum
airflow; wherein a positive air pressure airflow system is provided
and positioned to direct positive pressure air flow against at
least a portion of the upper surface of said flimsy print media
sheets being fed in said sheet transport system to blow said curled
towards said sheet feeding path.
2. The sheet transport system of claim 1, wherein said positive air
pressure airflow system providing a positive air pressure against
said flimsy print media sheets is provided by said exhaust airflow
output of said vacuum blower.
3. The sheet transport system of claim 1, wherein said non-vacuum
sheet transport system is a fuser imparting curl to at least some
of said flimsy print media sheets, which curled print media sheets
are being fed towards said vacuum sheet transport system, and
wherein said positive air pressure airflow system providing a
positive air pressure against said flimsy print media sheets is
blowing said sheets towards said vacuum sheet transport system to
assist in the engagement of said curled print media sheets by said
vacuum sheet transport system.
4. The sheet transport system of claim 1, wherein said positive air
pressure airflow system includes a positive air pressure manifold
extending transversely over at least one end of said vacuum sheet
transport system, spaced therefrom and feeding positive air
pressure air to one or more air jets providing positive pressure
air flow towards at least the leading edge area of said flimsy
print media sheets being fed onto said vacuum sheet transport
system.
5. In a sheet transport system with a sheet feeding path for
transporting flimsy print media sheets having a tendency for curled
sheet edges downstream in said sheet feeding path, said sheet
transport system including a downstream pneumatic vacuum sheet
transport system and an upstream non-vacuum sheet transport system
feeding said curled edge sheets onto said downstream pneumatic
vacuum sheet transport system; wherein said downstream pneumatic
vacuum sheet transport system has a pneumatic vacuum source with a
vacuum airflow input to said downstream pneumatic vacuum sheet
transport system for providing vacuum attraction of said sheets
against said downstream pneumatic vacuum sheet transport system,
and wherein said pneumatic vacuum source has a positive air
pressure exhaust airflow output system corresponding to said vacuum
airflow input, and wherein said positive air pressure exhaust
airflow output system is positioned to direct positive pressure air
flow towards at least the upstream edge of said downstream
pneumatic vacuum sheet transport system and towards a curled sheet
edge being fed onto said downstream pneumatic vacuum sheet
transport system by said upstream non-vacuum sheet transport
system, to blow said curled sheet edge towards vacuum engagement
with said downstream pneumatic vacuum sheet transport system.
6. The sheet transport system of claim 5, wherein said upstream
non-vacuum sheet transport system is a xerographic thermal roll
fuser imparting curl to said flimsy print media sheets.
7. A method of transporting flimsy print media sheets having curled
sheet edges comprising feeding said curled sheets out over a vacuum
sheet transport belt system and attracting the sheet there towards
with an underlying vacuum manifold airflow and simultaneously
blowing the upper surface of the sheet down towards said vacuum
belt transport with a positive pressure airflow, wherein both said
vacuum manifold airflow and said positive pressure airflow applied
to the upper surface of the sheet are respectively provided solely
by the air intake and the air exhaust from a single air blower.
8. The method of transporting flimsy print media sheets having
curled sheet edges of claim 7, wherein said positive pressure
airflow is provided from a positive air pressure manifold extending
transversely over at least the upstream end of said vacuum sheet
transport belt system, spaced therefrom, which positive air
pressure manifold is feeding air to one or more air jets providing
said positive pressure air flow towards at least the curled sheet
edge being fed out over said vacuum sheet transport belt system.
Description
[0001] Vacuum belt sheet transports are desirable for certain paper
paths of various xerographic printers and other sheet transporting
applications, especially in high speed printers. For example, for
providing the downstream sheet transport away from an upstream
fuser roll nip in which the xerographic toner images are thermally
fused onto the printed sheets. However, as is also well-known, such
print media sheets are typically relatively flimsy, and may have
tendencies to curl, due to ambient moisture, fusing, and other
factors. Where a print media sheet is fed out of a fuser or other
upstream transport with a lead edge curl, the sheet lead edge may
be curled away from the downstream surface of the vacuum belt
transport system. This can interfere with the vacuum acquisition
and hold-down of the sheet leading edge portion by the vacuum belt
transport system, and thus can even cause sheet jams and/or
slippage of the sheet relative to the sheet transport. Large area
color printing presents particularly difficult problems with sheet
curling tendencies, especially for duplex printing. Sheets with an
upwardly curled lead edge, especially if moving at a high enough
process speed (for example, in 120 or more pages per minute
printers), may be further lifted above the desired sheet feeding
path by bluff body forces and potentially "airplaning," that is,
aerodynamically lifting due to the media assuming a wing shape.
[0002] It will be appreciated by those skilled in the art that
vacuum belt sheet transport systems, and their typical fan blower
systems providing vacuums to vacuum plenums underlying the
transport belt(s), are well-known and need not be described in
detail herein. Some examples of vacuum belt transport systems are
disclosed in Xerox Corporation U.S. Pat. No. 4,294,540 issued Oct.
13, 1981; U.S. Pat. No. 4,618,138 issued Oct. 21, 1986; U.S. Pat.
No. 4,825,255 issued Apr. 25, 1989; U.S. Pat. No. 4,831,419 issued
May 16,1989; and U.S. Pat. No. 4,921,240 issued May 1,1990.
[0003] Disclosed in the embodiment herein is a very low cost system
for helping to overcome this problem, in which the exhaust or
pressure side of the existing vacuum blower or other vacuum source
for the vacuum transport system may be utilized to provide a
downward air jet system acting on an upwardly curled sheet lead
edge area to blow the sheet down towards the vacuum transport belt
system in cooperation with its existing vacuum attraction system.
Thereby the curled sheet may be acquired earlier and/or more
effectively for further downstream transporting of the sheet on the
vacuum sheet transport system.
[0004] That is, as disclosed in the embodiment herein, the normally
vented exhaust of a vacuum blower system may be utilized to create
a positive pneumatic force above the curled sheet to force the
curled sheet down closer to the vacuum plenum of the vacuum sheet
transport belt system for improved sheet acquisition thereby.
However, it will be appreciated that, although more costly, two
separate blowers could be provided for the dual airflows system
disclosed herein, providing an independent positive air pressure
source.
[0005] Although a post-fuser vacuum transport system utilization is
illustrated here, the present system may be utilized in various
other sheet transport applications. For example, to overcome the
tendency of the trailing edge of a sheet to flip up as it goes into
a roll pressure fuser in which the outer edges of the sheet are
pulled into the fuser nip slightly faster than the center of the
sheet. In a post-fuser vacuum transport system the disclosed
embodiment can provide enhanced air flow against the sheet which
can provide additional advantages of enhanced or faster cooling and
moisture dissipation of the heated sheets exiting a typical
xerographic thermal toner image fuser of a xerographic printer.
[0006] It has been found that the positive pressure and downward
force on the top surface of a curled sheet from an impinging flow
of positive air pressure air jets from the vacuum blower exhaust
source, or other source, can be initially much larger than the
downward force on that same curled sheet edge bottom surface from
the airflow from the vacuum plenum of the underlying vacuum
transport. This curled sheet acquisition or control system
efficiency improvement can also further enhance sheet transport
when the sheet is too narrow or small to fully cover enough of the
vacuum ports of the vacuum plenum of the vacuum sheet transport
system.
[0007] With no significant increase in cost (only minor thin wall
plastic or metal ducting additions), with no extra blower motors
required, and with no increase in power requirements (even a
possible power reduction), the combination of positive air pressure
force applied on the top of the sheet and negative air pressure
applied from underneath the sheet can increase the total sheet
downward or normal force, and therefore improve the sheet forward
feeding force with reduced slippage of the sheet relative to its
vacuum belt sheet transport system. The total flow for both sheet
acquisition and sheet traction is more efficient.
[0008] Even with or after sheet acquisition, significant vacuum
transport air leakage flow may exist, affecting transport of
acquired sheets, especially for smaller media sizes which leave
many of the vacuum ports uncovered by the media. Also, media with
edges that curl downwardly towards the transport belt(s) may appear
to be acquired but may not be sufficiently. The augmenting positive
airflow from above can further flatten such sheets down against the
vacuum transport and thus minimize its potential for slippage.
[0009] In the Figures of the embodiment a pressure plenum and air
jets are illustrated as overlying only the upstream or sheet input
end of the vacuum sheet transport system, for maximum effect on the
entering sheet's leading area. However, optionally, additional
positive downward airflow and air pressure may be similarly applied
for a further downstream distance overlying much more of the vacuum
sheet transport system to enhance the normal force of the paper
against the transport belts from a combination of the underlying
vacuum and the overlying air pressure over a much larger area.
[0010] It will be appreciated by those skilled in the art that it
is known in the art to use, in sheet-separator-feeders, which have
vacuum corrugating sheet feed heads, the exhaust from the vacuum
blower for angled air knives assisting the lifting and separation
of sheets in a stack of sheets in the sheet feeder to be acquired
and fed by the sheet feed head. Such sheet-separator air knives may
blow laterally toward the side or front edge of the stack of sheets
for sheet separation before acquisition. For example, U.S. Pat. No.
6,186,492 issued Feb. 13, 2001 to Dechau, et al; U.S. Pat. No.
6,264,188 issued Jul. 24, 2001 to Taylor, et al; and U.S. Pat. No.
6,352,255 issued Mar. 5, 2002 to Taylor.
[0011] A specific feature of the specific embodiment disclosed
herein is to provide a sheet transport system with a sheet feeding
path for transporting flimsy print media sheets having upper and
lower surfaces, at lease some of which flimsy print media sheets in
said sheet transport system are curled, said sheet transport system
including at least one vacuum sheet transport system and at least
one non-vacuum sheet transport system; wherein said vacuum sheet
transport system has a vacuum blower providing a vacuum airflow to
said vacuum sheet transport system for providing vacuum attraction
of the lower surface of said sheets against said vacuum sheet
transport system, and wherein said vacuum blower has a positive air
pressure exhaust airflow output corresponding to said vacuum
airflow; wherein a positive air pressure airflow system is provided
and positioned to direct positive pressure air flow against at
least a portion of the upper surface of said flimsy print media
sheets being fed in said sheet transport system to blow said curled
towards said sheet feeding path.
[0012] Further specific features disclosed in the embodiment
herein, individually or in combination, include those wherein rein
said positive air pressure airflow system providing a positive air
pressure against said flimsy print media sheets is provided by said
exhaust airflow output of said vacuum blower; and/or wherein said
non-vacuum sheet transport system is a fuser imparting curl to at
least some of said flimsy print media sheets, which curled print
media sheets are being fed towards said vacuum sheet transport
system, and wherein said positive air pressure airflow system
providing a positive air pressure against said flimsy print media
sheets is blowing said sheets towards said vacuum sheet transport
system to assist in the engagement of said curled print media
sheets by said vacuum sheet transport system; and/or wherein said
positive air pressure airflow system includes a positive air
pressure manifold extending transversely over at least one end of
said vacuum sheet transport system, spaced therefrom and feeding
positive air pressure air to one or more air jets providing
positive pressure air flow towards at least the leading edge area
of said flimsy print media sheets being fed onto said vacuum sheet
transport system; and/or a sheet transport system with a sheet
feeding path for transporting flimsy print media sheets having a
tendency for curled sheet edges downstream in said sheet feeding
path, said sheet transport system including a downstream pneumatic
vacuum sheet transport system and an upstream non-vacuum sheet
transport system feeding said curled edge sheets onto said
downstream pneumatic vacuum sheet transport system; wherein said
downstream pneumatic vacuum sheet transport system has a pneumatic
vacuum source with a vacuum airflow input to said downstream
pneumatic vacuum sheet transport system for providing vacuum
attraction of said sheets against said downstream pneumatic vacuum
sheet transport system, and wherein said pneumatic vacuum source
has a positive air pressure exhaust airflow output system
corresponding to said vacuum airflow input, and wherein said
positive air pressure exhaust airflow output system is positioned
to direct positive pressure air flow towards at least the upstream
edge of said downstream pneumatic vacuum sheet transport system and
towards a curled sheet edge being fed onto said downstream
pneumatic vacuum sheet transport system by said upstream non-vacuum
sheet transport system, to blow said curled sheet edge towards
vacuum engagement with said downstream pneumatic vacuum sheet
transport system; and/or wherein said upstream non-vacuum sheet
transport system is a xerographic thermal roll fuser imparting curl
to said flimsy print media sheets; and/or a method of transporting
flimsy print media sheets having curled sheet edges comprising
feeding said curled sheets out over a vacuum sheet transport belt
system and attracting the sheet there towards with an underlying
vacuum manifold airflow and simultaneously blowing the upper
surface of the sheet down towards said vacuum belt transport with a
positive pressure airflow, wherein both said vacuum manifold
airflow and said positive pressure airflow applied to the upper
surface of the sheet are respectively provided solely by the air
intake and the air exhaust from a single air blower; and/or wherein
said positive pressure airflow is provided from a positive air
pressure manifold extending transversely over at least the upstream
end of said vacuum sheet transport belt system, spaced therefrom,
which positive air pressure manifold is feeding air to one or more
air jets providing said positive pressure air flow towards at least
the curled sheet edge being fed out over said vacuum sheet
transport belt system.
[0013] The term "reproduction apparatus" or "printer" as used
herein broadly encompasses various printers, copiers or
multifunction machines or systems, xerographic or otherwise, unless
otherwise defined in a claim. The term "sheet" herein refers to a
usually flimsy physical sheet of paper, plastic, or other suitable
physical substrate for images, whether precut or web fed.
[0014] As to specific components of the subject apparatus or
method, or alternatives therefor, it will be appreciated that, as
is normally the case, some such components are known per se in
other apparatus or applications, which may be additionally or
alternatively used herein, including those from art cited herein.
For example, it will be appreciated by respective engineers and
others that many of the particular component mountings, component
actuation's, or component drive systems illustrated herein are
merely exemplary, and that the same novel motions and functions can
be provided by many other known or readily available alternatives.
All cited references, and their references, are incorporated by
reference herein where appropriate for teachings of additional or
alternative details, features, and/or technical background. What is
well known to those skilled in the art need not be described
herein.
[0015] Various of the above-mentioned and further features and
advantages will be apparent to those skilled in the art from the
specific apparatus and its operation or methods described in the
example below, and the claims. Thus, the present invention will be
better understood from this description of this specific
embodiment, including the drawing figures (which are approximately
to scale, except that the vacuum belt sheet transport would
typically be longer than as illustrated here) wherein:
[0016] FIG. 1 is a partially schematic side view of an improved
sheet acquisition and transport system, as one example of the
subject system; and
[0017] FIG. 2 is a top view of the system of FIG. 1.
[0018] Referring in more detail to the exemplary sheet acquisition
and transport system 10 of FIGS. 1 and 2, only those relevant
portions of an otherwise conventional exemplary xerographic printer
need be illustrated. In particular, a conventional xerographic roll
fuser 12 is sequentially feeding out printed and fused sheets 14,
at least some of which sheets 14 will have an upward lead edge
curl, as illustrated. This upward lead edge curl of the sheet 14
can interfere with the desired acquisition of that sheet 14 down
onto the moving transport belts 22 of a conventional vacuum sheet
transport system 16 downstream of the fuser 12 by lifting that area
of the sheet 14 up away from that transport system 16. The vacuum
sheet transport system 16 has a conventional underlying apertured
vacuum plenum 18 connected by a conventional negative pressure
manifold to the suction side or input of a conventional vacuum
blower 30. The vacuum sheet transport system 16 may be of variable
lengths, depending on the printer paper path requirements, and
typically has driving or supporting rollers 24A, 24B supporting
opposite ends of the belts 22. All of the preceding is well-known
to those skilled in the art and need not be described in further
detail herein.
[0019] In this improved system 10, what would normally be an open
exhaust for the vacuum blower 30 is instead connected to a closed
positive air pressure conducting or manifold system connecting to a
positive air pressure plenum 32. The plenum 32 extends transversely
across the sheet feed path overlying the vacuum belt sheet
transport system 16 with downwardly opening slits 32A providing
downwardly projecting air jets acting against the top of the sheet
14 curled up forward edge area coming out of the fuser 12 nip,
thereby pushing the forward edge of the sheet 14 down against the
vacuum sheet transport system 16 in cooperation with the airflow
from the vacuum in the negative pressure manifold 20 under the
belts 22, thereby enabling the relatively planar transport of the
sheet 14 along the generally planar top surface of the belts 22
with good acquisition and with reduced danger of a rapidly moving
sheet 14 "airplaning" away from the belts 22.
[0020] The slots 32A (slots or holes) in the positive pressure
plenum 32 providing downward air jets in the disclosed embodiment
may be sized to provide sufficient velocity to their issuing
airflow such that the stagnation pressure generated from the jet
impingement is substantially larger than the lift forces created by
the beam strength of the curled sheet and the pneumatic lift or
airplaning forces from the forward movement of even a curl sheet
moving at relatively high process speed. For example, a plurality
of only about 0.6 cm wide slots 32A extending transversely across
the sheet feed path at a flow rate of only about 0.5 cubic meters
per second was found to be sufficient in one test fixture.
[0021] It will be appreciated that various presently unforeseen or
unanticipated alternatives, modifications, variations or
improvements therein may be subsequently made by those skilled in
the art which are also intended to be encompassed by the following
claims.
* * * * *