U.S. patent application number 11/394321 was filed with the patent office on 2007-10-11 for constant lead edge paper inverter system.
This patent application is currently assigned to Xerox Corporation. Invention is credited to David Cipolla, Donald Eugene Johnston.
Application Number | 20070235925 11/394321 |
Document ID | / |
Family ID | 38574388 |
Filed Date | 2007-10-11 |
United States Patent
Application |
20070235925 |
Kind Code |
A1 |
Johnston; Donald Eugene ; et
al. |
October 11, 2007 |
Constant lead edge paper inverter system
Abstract
A printing apparatus capable of duplex imaging that maintains
the lead edge of a sheet constant, is disclosed. The printing
apparatus includes a first transport path to route a sheet along a
processing direction, an edge position detector to detect a lead
edge of the sheet, a marking device that prints on a first side of
the sheet, a second transport path to receive the sheet from the
marking device, and an inverter mechanism that receives the sheet
from the second transport path and inverts the sheet along a
cross-processing direction that is perpendicular to the processing
direction. The printing apparatus also includes a third transport
path that receives the inverted sheet and routes the inverted sheet
back to the first transport path. With this configuration, upon
being routed back to the first transport path, the edge position
detector detects the same lead edge of the sheet as previously
detected and the marking device prints on a second side of the
sheet.
Inventors: |
Johnston; Donald Eugene;
(Webster, NY) ; Cipolla; David; (Macedon,
NY) |
Correspondence
Address: |
PILLSBURY WINTHROP SHAW PITTMAN, LLP
P.O. BOX 10500
MCLEAN
VA
22102
US
|
Assignee: |
Xerox Corporation
Stamford
CT
|
Family ID: |
38574388 |
Appl. No.: |
11/394321 |
Filed: |
March 31, 2006 |
Current U.S.
Class: |
271/301 |
Current CPC
Class: |
G03G 15/234 20130101;
G03G 2215/00438 20130101 |
Class at
Publication: |
271/301 |
International
Class: |
B65H 39/10 20060101
B65H039/10 |
Claims
1. A printing apparatus, comprising: a first transport path
configured to route a sheet along a processing direction; an edge
position detector configured to detect a lead edge of the sheet; a
marking device configured to print on a first side of the sheet; a
second transport path configured to receive the sheet from the
marking device; an inverter mechanism configured to receive the
sheet from the second transport path and invert the sheet along a
cross-processing direction that is perpendicular to the processing
direction; and a third transport path configured to receive the
inverted sheet and route the inverted sheet back to the first
transport path, wherein, upon being routed back to the first
transport path, the edge position detector detects the same lead
edge of the sheet and the marking device prints on a second side of
the sheet.
2. The printing apparatus of claim 1, wherein the inverter
mechanism comprises a U-shaped inverter.
3. The printing apparatus of claim 2, wherein the U-shaped inverter
includes a plurality of rolls.
4. The printing apparatus of claim 2, wherein the U-shaped inverter
includes a vacuum transport.
5. The printing apparatus of claim 1, wherein the first, second,
and third transport paths are arranged to form a circuit path.
6. The printing apparatus of claim 1, wherein the first, second,
and third transport paths include a plurality of drive roller nips
that engage the sheet and are oriented and aligned to guide the
sheet along the processing direction.
7. The printing apparatus of claim 1, wherein the inverter
mechanism includes a plurality of cross-drive roller nips that
engage the sheet and are oriented and aligned to guide the sheet
along the cross-processing direction.
8. The printing apparatus of claim 1, wherein the first transport
path includes an input portion to initially receive the sheet and
an output portion to output the sheet.
9. The printing apparatus of claim 1, wherein the second transport
path includes an intake portion to receive the sheet from the first
transport path.
10. The printing apparatus of claim 1, wherein the third transport
path includes an output portion to direct the sheet back to the
first transport path.
11. A sheet inverter mechanism, comprising: a U-shaped inverter
configured to receive a sheet along a processing direction; and a
plurality of roller nips oriented and arranged to engage and drive
the sheet across the U-shaped inverter to invert the sheet, the
sheet being inverted along a cross-processing direction that is
perpendicular to the processing direction, wherein a lead edge of
the sheet prior to being inverted remains on a same side after
being inverted.
12. A method of printing on opposite sides of a sheet, comprising:
routing the sheet across a first transport path along a processing
direction; detecting a lead edge of the sheet; printing on one side
of the sheet; routing the sheet across a second transport path;
inverting the sheet along a cross-processing direction that is
perpendicular to the processing direction; routing the sheet across
a third transport path that feeds back towards the first transport
path; detecting the same lead edge; and printing on a second side
of the sheet.
13. The method of claim 12, wherein the inverting of the sheet
includes engaging and driving the sheet across a U-shaped inverter
along the cross-processing direction.
14. The method of claim 12, wherein the first, second, and third
transport paths are arranged to form a circuit path.
15. The method of claim 12, wherein the routing of the sheet within
the first, second, and third transport paths includes the use of a
plurality of drive roller nips that are oriented and aligned to
engage and guide the sheet along the processing direction.
16. The method of claim 12, wherein the inverting of the sheet
includes the use of a plurality of cross-drive roller nips that are
oriented and aligned to engage and guide the sheet along the
cross-processing direction.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of Invention
[0002] The present disclosure relates to digital document
production equipment and, more specifically, to duplex capable
imaging machines.
[0003] 2. Description of Related Art
[0004] Digital document production equipment is very common in
today's office environment. Generally, such equipment, which
includes printers, copiers, facsimiles, or other multifunction
machines, is configured to place text and images, based on digital
data, onto media, such as paper sheets.
[0005] By way of example, consider the case of digital copiers,
where original documents bearing images to be recorded on paper
sheets are typically loaded into the tray of a document handler.
The documents are drawn one sheet at a time and moved relative to
an image sensor. The image sensor records reflected light from a
series of small areas in the original image as the image moves past
the sensor to yield a set of digital signals representative of the
image to be recorded on a sheet of paper. The digital signals are
then supplied to a marking device, such as, for example, an
electrophotographic laser printing device or an inkjet printhead
device, which renders the recorded image on one side of the sheet
of paper as the sheet passes across the marking device.
[0006] To ensure proper image placement and alignment, the digital
copier also employs an edge position detector. The edge position
detector is configured to determine the location of a side edge of
the sheet relative to a fixed point within the copier. That is,
prior to subjecting the sheet to the marking device, the sheet
passes over the edge position detector that registers the side edge
of the sheet to ensure proper alignment and placement of the
recorded image as the sheet is guided across the marking
device.
[0007] More sophisticated types of document production equipment
are also capable of rendering images on both sides of a single
sheet of paper, a feature commonly referred to as "duplexing" or
"duplex imaging." In order to print on both sides of the same
sheet, duplex capable machines typically feed a sheet through the
edge detector and marking device a first time to receive a first
image on one side thereof, suck the sheet back out, invert or flip
the sheet, and then re-feed the sheet back through the edge
detector and marking device so that the device can place a second
image on the opposite side of the sheet. The path by which the
sheet has been output by the marking device, inverted, and re-fed
back to the marking device, is generally referred to as the "duplex
path." Although the specific architectures vary, most conventional
duplex paths employ an inverter transport loop that guides the lead
edge of the paper sheet over the trail edge to effectively flip the
sheet.
[0008] Ideally, the registration of duplexed images should result
in images recorded on opposite sides of the sheet to be
substantially aligned with each other. In other words, the margins
of the images on opposite sides of the sheet should appear to be
superimposed. However, as a practical matter, after the sheet has
been sucked out and flipped by the inverter transport loop, the
edge detector registers the side edge of the sheet that is opposite
to the initially detected side edge, in anticipation of the sheet
being re-fed back to the marking device. It will be appreciated
that, given paper length and cut angle tolerances, the use and
registration of opposite side edges increases the risks of duplex
image misalignment and placement errors.
SUMMARY OF THE INVENTION
[0009] Principles of the present invention, as embodied and broadly
described herein, provide a printing apparatus capable of duplex
imaging that maintains the lead edge of a sheet constant. In one
embodiment, the printing apparatus includes a first transport path
to route a sheet along a processing direction, an edge position
detector to detect a lead edge of the sheet, a marking device that
prints on a first side of the sheet, a second transport path to
receive the sheet from the marking device, and an inverter
mechanism that receives the sheet from the second transport path
and inverts the sheet along a cross-processing direction that is
perpendicular to the processing direction. The printing apparatus
also includes a third transport path that receives the inverted
sheet and routes the inverted sheet back to the first transport
path. With this configuration, upon being routed back to the first
transport path, the edge position detector detects the same lead
edge of the sheet as previously detected and the marking device
prints on a second side of the sheet.
[0010] Other embodiments include a method of printing on opposite
sides of a sheet, comprising routing the sheet across a first
transport path along a processing direction, detecting a lead edge
of the sheet, printing on one side of the sheet, routing the sheet
across a second transport path, inverting the sheet along a
cross-processing direction that is perpendicular to the processing
direction, and routing the sheet across a third transport path that
feeds back towards the first transport path. The method further
includes detecting the same lead edge, and printing on a second
side of the sheet.
BRIEF DESCRIPTION OF DRAWINGS
[0011] The accompanying drawings, which are incorporated in and
constitute a part of the present patent specification, depict
corresponding embodiments of the invention, by way of example only,
and it should be appreciated that corresponding reference symbols
indicate corresponding parts. In the drawings:
[0012] FIG. 1 depicts the principle of elements of duplex-capable
printing apparatus, in accordance with an embodiment of the present
invention;
[0013] FIG. 2A depicts features of a sheet to be processed by the
duplex-capable printing apparatus of FIG. 1; and
[0014] FIG. 2B is a simplified diagram of FIG. 1 that depicts the
orientation and alignment of a sheet at different time
intervals.
DETAILED DESCRIPTION OF THE INVENTION
[0015] As will be evident by the ensuing detailed description, the
present invention provides a printing apparatus and method of
providing duplex imaging with single lead edge registration.
[0016] FIG. 1 schematically depicts the principle elements of the
image processing station of a duplex capable printing apparatus
100, in accordance with an embodiment of the present invention.
Such an apparatus is intended to cover printers, copiers,
facsimiles, or other multifunction machines that are capable of
duplex imaging. As illustrated in FIG. 1, printing apparatus 100
comprises a side edge position detector 110, a marking device 120,
a simplex transport path 130, and a constant lead edge paper
inverter system 160. In turn, constant lead edge inverter system
160 comprises an upper duplex transport path 140 and a lower duplex
transport path 150. The orientation of FIG. 1 is depicted so that
the image processing direction, that is, the general direction in
which a sheet of paper is transported and routed to receive an
image, is indicated by P, while the cross processing direction
(i.e., perpendicular to P) is indicated by P'.
[0017] As shown in FIG. 1, simplex transport path 130, configured
for single-sided imaging and for accommodating possible duplex
imaging, comprises a plurality of drive roller nips 102 oriented to
guide a sheet of paper across side edge position detector 110 and
marking device 120 along the image processing direction P. That is,
in the case of single-sided imaging in which the digital signals
representative of the captured image have been supplied to marking
device 120, the sheet is supplied to and enters the simplex
transport path 130 at intake portion 131 and drive roller nips 102
engage the sheet and transport the sheet across side edge position
detector 110. Side edge position detector 110 registers the side
edge of the sheet, in this case, the lead edge, to ensure proper
alignment and placement of the recorded image. After registering
the side edge, drive roller nips 102 guide the sheet across marking
device 120 to record the captured image onto one side of the sheet.
Finally, the single-sided imaged sheet is then routed to an output
portion 139 of simplex path 130.
[0018] As noted above, constant lead edge inverter system 160
comprises an upper duplex transport path 140 and a lower duplex
transport path 150. In turn, upper duplex transport path 140
comprises U-shaped inverter 145, a plurality of drive roller nips
102 configured to guide and transport the sheet to inverter 145, a
plurality of cross-direction drive roller nips 142 and a sensor 143
configured to identify the lead edge of the sheet at a constant
stop point S. U-shaped inverter 145 may comprise rolls, vacuum
transport, or any mechanism suitable for such purposes.
[0019] Both U-shaped inverter 145 and cross-direction drive roller
nips 142 are oriented and configured to operate along the
cross-process direction P' direction. In particular, the
combination of U-shaped inverter 145 and cross-direction drive
roller nips 142 cooperate to receive and engage the sheet of paper
containing a previously recorded image on one side, flip the sheet
along the cross-process direction P' to the opposite side, and
forward the flipped sheet to lower duplex transport path 150.
[0020] Lower duplex transport path 150 is configured to receive and
route the flipped sheet back over to the intake portion 131 of
simplex transport path 130 in order for the marking device 120 to
record a second image on the blank side of the sheet.
[0021] In an exemplary embodiment, consider the case in which
duplex imaging has been selected and the two images to be recorded
on opposite sides of the sheet have been digitally captured by the
image sensor (not shown), so that the digital signals
representative of the captured images have been supplied to marking
device 120. Initially, much like the single-sided imaging case, the
sheet is supplied to and enters the simplex transport path 130 at
intake portion 131, so that drive roller nips 102 engage the sheet
and transport the sheet across side edge position detector 110. The
detector 110 registers the side edge (i.e., the lead edge) of the
sheet to ensure proper alignment and placement of the first
recorded image. After registering the side edge, drive roller nips
102 guide the sheet across marking device 120 to record the first
captured image onto one side of the sheet. However, unlike the
single-sided imaging case, where the single-sided imaged sheet is
routed the to output portion 139, the sheet is routed to duplex
path intake portion 141.
[0022] For the sake of clarity regarding the subsequent description
of constant lead edge inverter system 160, reference is made to
FIGS. 2A, 2B. FIG. 2A illustrates a sheet having a blank side SH1
onto which a second image will be recorded thereon, a side SH2
having a first recorded image, and the lead side edge E of the
sheet having been identified and registered by side edge position
detector 110. FIG. 2B illustrates the operation of constant lead
edge inverter system 160 at different time intervals ti.
[0023] With this said, time interval t1 represents the sheet after
passing through side edge position detector 110 and marking device
120, in which the first image is recorded on side SH2. After time
interval t1, the sheet is routed to duplex path intake portion 141
where the drive roller nips 102 engage the sheet and transport the
sheet along the upper process direction P, as indicated by time
interval t2.
[0024] The sheet continues to be transported along the upper
process direction P until reaching the upper drive roller nips 102
at the U-shaped inverter 145, as indicated by time interval t3. At
this point, sensor 143, disposed proximate to the distal end of
U-shaped inverter 145, identifies the lead edge of the sheet at a
constant stop point S under the cross-direction drive roller nips
142. Upon reaching constant stop point S, the sheet is stopped and
cross-direction drive roller nips 142 engage the sheet while drive
roller nips 102 disengage. As depicted in FIG. 2B, the sheet is
turned upside down so that recorded side SH2 is on top and blank
side SH1 is on the bottom. It will be appreciated that, at this
point, other quality control measures may be taken to further
ensure proper alignment and image placement. For example, with the
sheet being in a prone position on top of U-shaped inverter 145,
gross deskewing and top edge registration could be performed to
measure and account for side edge skew.
[0025] At time interval t4, the cross-direction drive roller nips
142 drive the sheet in the cross-process direction P' of the
U-shaped inverter 145. The combination of cross-direction drive
roller nips 142 and inverter 145 effectively flips the sheet and
feeds the sheet to lower duplex transport path 150, where the
cross-direction drive roller nips 142 disengage and drive roller
nips 102 on the lower path engage the sheet. As depicted in FIG.
2B, the flipping results in the sheet having blank side SH1 on top
while recorded side SH2 is on the bottom. However, as also
indicated in the figure, the lead edge E remains on the same side
after the sheet is flipped.
[0026] As indicated by time interval t5, the lower path drive
roller nips 102 transport the sheet along the lower processing path
onto duplex output portion 159, which directs the sheet back into a
beginning portion of simplex path 130.
[0027] At time interval t6, the sheet is placed back on simplex
path 130 prior to being imaged for the second time. As depicted in
FIG. 2B, by virtue of the lower duplex transport path 150, the
sheet is once again turned upside down so that recorded side SH2 is
on top and blank side SH1 is on the bottom. However, as noted
above, lead edge E of the sheet remains on the side after the sheet
is flipped. Subsequently, the drive roller nips 102 on the simplex
path 130 engage the sheet and transport the sheet across side edge
position detector 110, detector 110 registers the same lead edge E
of the sheet, as previously registered. After registering the lead
edge E, drive roller nips 102 guide the sheet again across marking
device 120 to record the second captured image onto the blank side
SH1 of the sheet, and thereafter, the duplex imaged sheet is routed
to output portion 139.
[0028] Given the above-described configuration, printing apparatus
100 is capable of rendering images on both sides of the sheet while
maintaining the same lead edge. The presentation of the same lead
edge to the edge detector for both the pre-inverted and
post-inverted sheet, reduces the risks of duplex image misalignment
and placement errors due to the use and registration of opposite
side edges. Other advantages may include higher throughput speeds,
as the cross-direction drive roller nips do not have to reverse
directions as conventional roller nips do when the sheets have to
be sucked back out prior to flipping.
[0029] It will be appreciated that various of the above-disclosed
and other features and functions, or alternatives thereof, may be
desirably combined into many other different systems or
applications. Also 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.
* * * * *