U.S. patent application number 15/766735 was filed with the patent office on 2019-02-28 for preventing media misalignment during accumulation.
The applicant listed for this patent is Hewlett-Packard Development Company, L.P.. Invention is credited to Elliott Downing, Anthony W Ebersole, Bruce G Johnson, Steve O Rasmussen.
Application Number | 20190062097 15/766735 |
Document ID | / |
Family ID | 59013854 |
Filed Date | 2019-02-28 |
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United States Patent
Application |
20190062097 |
Kind Code |
A1 |
Johnson; Bruce G ; et
al. |
February 28, 2019 |
PREVENTING MEDIA MISALIGNMENT DURING ACCUMULATION
Abstract
In one example in accordance with the present disclosure a
system for preventing media misalignment during accumulation. The
system includes a number of media clamps having multiple positions
to prevent misalignment of an incoming media sheet during
accumulation. The number of media clamps are in a raised position
after a leading edge of the incoming media sheet has passed over a
trailing edge of the stack region. The media clamps are in a
clamped position after the leading edge of the incoming media sheet
has passed the media clamp.
Inventors: |
Johnson; Bruce G; (LaCenter,
WA) ; Downing; Elliott; (Vancouver, WA) ;
Rasmussen; Steve O; (Vancouver, WA) ; Ebersole;
Anthony W; (Vancouver, WA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hewlett-Packard Development Company, L.P. |
|
|
|
|
|
Family ID: |
59013854 |
Appl. No.: |
15/766735 |
Filed: |
December 9, 2015 |
PCT Filed: |
December 9, 2015 |
PCT NO: |
PCT/US1015/064656 |
371 Date: |
April 6, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65H 2557/61 20130101;
B65H 2511/10 20130101; B65H 31/34 20130101; B65H 31/26 20130101;
B65H 31/38 20130101; B65H 2701/1311 20130101; B65H 2511/21
20130101; B65H 2301/4212 20130101; B65H 2801/15 20130101; B65H
2220/09 20130101; B65H 2601/211 20130101; B65H 2511/10 20130101;
B65H 2220/01 20130101; B65H 2511/21 20130101; B65H 2220/02
20130101; B65H 2220/11 20130101; B65H 2701/1311 20130101; B65H
2220/01 20130101 |
International
Class: |
B65H 31/26 20060101
B65H031/26; B65H 31/34 20060101 B65H031/34 |
Claims
1. A system for preventing media misalignment during accumulation,
the system comprising: a number of media clamps having multiple
positions to prevent misalignment of an incoming media sheet during
accumulation, wherein the number of media clamps: are in a raised
position after a leading edge of the incoming media sheet has
passed over a trailing edge of the stack region; and are in a
clamped position after the leading edge of the incoming media sheet
has passed the number of media clamps.
2. The system of claim 1, wherein the number of media clamps are
proximate the trailing edge of the stack region.
3. The system of claim 1, wherein the number of media clamps form a
set selected from a number of sets of media claims, each set
pertaining to a different media size.
4. The system of claim 1, wherein: a raised position comprises an
intermediate position and a high position; the number of media
clamps are in the high position after the leading edge of the
incoming media sheet has passed over the trailing edge of the stack
region; and the number of media clamps are in the intermediate
position during an x-direction alignment of the incoming media
sheet.
5. The system of claim 4, wherein the number of media clamps are in
the intermediate position for a portion of a y-direction alignment
of the incoming media sheet.
6. The system of claim 1, wherein the number of media clamps are in
a clamped position until a leading edge of the incoming media sheet
has passed over the trailing edge of the stack region.
7. A method for preventing misalignment of an incoming media sheet,
the method comprising: placing media clamps having multiple
positions in a clamped position until a leading edge of the
incoming media sheet has passed over a trailing edge of a stack
region; raising the media clamps after the leading edge of the
incoming media sheet has passed over the trailing edge of the stack
region; and lowering the media clamps to align the incoming media
sheet with the stack region after the leading edge of the incoming
media sheet has passed the media clamp.
8. The method of claim 7, further comprising: lowering the media
clamps to an intermediate position during an x-direction alignment
of the incoming media sheet; and lowering the media clamps to a
clamped position for at least a portion of a y-direction alignment
of the incoming media sheet.
9. The method of claim 7, wherein raising the media clamps
comprises raising the media clamps to a high position after the
leading edge of the incoming media sheet has passed over the
trailing edge of the stack region.
10. The method of claim 7, further comprising receiving at least a
partially-dry incoming media sheet.
11. The method of claim 7, further comprising calibrating an
intermediate height of a set of media clamps relative to a media
support device by: lowering the media clamps to an elevation lower
than the media support device; translating the media support device
towards the media clamps; detecting contact between the media
support device and the media clamps; incrementally raising the
media clamp and translating the media support device towards the
media clamps until no contact is detected between the media support
device and the media clamps; and once no contact is detected
between the media support device and the media clamps, raising the
media clamps a predetermined distance.
12. A system for preventing misalignment of an incoming media
sheet, the system comprising: a number of sets of media clamps
having multiple positions, each set of media clamps corresponding
to a different media size, each set to: manage alignment of an
incoming media sheet when the incoming media sheet is of a
corresponding media size, wherein when managing alignment of an
incoming media sheet, a set of media clamps: are in a clamped
position until a leading edge of the incoming media sheet has
passed over a stack region of a media support device; are in a
raised position after the leading edge of the incoming media sheet
has passed over a trailing edge of the stack region; and return to
the clamped position to maintain an alignment of the incoming media
sheet relative to the stack region; and be in a raised position
when an incoming media sheet is not of a corresponding media
size.
13. The system of claim 12, wherein a set of media clamps are
aligned with the stack region of a corresponding media size.
14. The system of claim 12, wherein motion of media clamps within a
set is independently controlled to allow equal contact of the media
clamps within the set on at least one of a media stack and media
support assembly.
15. The system of claim 12, wherein at least one set of media
clamps is actuated by motion of a media transport assembly.
Description
BACKGROUND
[0001] Printing systems are used to deposit printing fluid such as
ink, onto a print medium such as paper. After the print medium has
been printed on, additional operations such as stapling, collating,
offsetting a stack, and other post-printing operations may be
performed on a stack of printed media.
BRIEF DESCRIPTION OF THE DRAWINGS
[0002] The accompanying drawings illustrate various examples of the
principles described herein and are a part of the specification.
The illustrated examples are given merely for illustration, and do
not limit the scope of the claims.
[0003] FIGS. 1A-1C are examples of a system for preventing media
misalignment during accumulation, according to one example of the
principles described herein.
[0004] FIG. 2 is a flowchart of a method for preventing media
misalignment during accumulation, according to one example of the
principles described herein.
[0005] FIG. 3 is a top view of a system for preventing media
misalignment during accumulation, according to another example of
the principles described herein.
[0006] FIG. 4 is a side view of the system of FIG. 3, according to
one example of the principles described herein.
[0007] FIG. 5 is a flowchart of a method for preventing media
misalignment during accumulation, according to another example of
the principles described herein.
[0008] FIG. 6 is a side view of a media clamp for preventing media
misalignment during accumulation, according to one example of the
principles described herein.
[0009] FIGS. 7A-7E are diagrams of the method for calibrating a
media clamp, according to one example of the principles described
herein.
[0010] FIG. 8 is a diagram of a media clamp, according to another
example of the principles described herein.
[0011] Throughout the drawings, identical reference numbers
designate similar, but not necessarily identical, elements.
DETAILED DESCRIPTION
[0012] As described above, printing systems are used to deposit a
printing fluid such as ink, onto a print medium such as paper.
Other examples of print fluids include three-dimensional print
agents, bio-fluids, pharmaceutical agents, etc. Other examples of
print medium include three-dimensional printing medium such as
powder. After a printing system has deposited the ink onto the
print medium, a finishing system that may be separate from, or
integral with, the printing system executes finishing operations
such as, but not limited to, aligning the stack, offsetting the
media sheets, and stapling the media sheets together. While these
finishing systems are useful at performing such operations, they
are less efficient in some scenarios.
[0013] For example, during finishing operations, it is desirable
for both the long and short edges of the media to be well-aligned
to accommodate those finishing operations. Accordingly, a finishing
system, which again may be separate from or integral with a
printing system, should have sufficient control over a media sheet
to be able to move the media sheet along multiple axes to align the
edges and to maintain this alignment for subsequent operations.
Such operations are difficult and become even more difficult when
working with certain media, such as undried or partially-dried
media.
[0014] For example, media with undried or partially-dried printing
fluid may distort due to the expansion of fibers in the media. The
expansion of these fibers causes curl and cockle in the print
medium. Also, the presence of a printing fluid reduces the beam
strength, i.e., the stiffness, of the media sheet such that it has
a higher tendency to buckle under an applied force. Still further,
as ink is deposited on the surface of the media sheet, the
expansion of the paper fibers on the surface changes the surface
properties which increases the surface frictional properties of the
media sheet. Each of these conditions complicates the handling of
media sheets that have been printed on with a printing fluid.
[0015] One specific complication is sheet curl that results as a
sheet distorts due to the application of a printing fluid. If a
previously printed sheet in a media stack has enough curl, an
incoming media sheet may interact with the previously printed sheet
and pull the sheet in the stack over on itself. Still further, if
an incoming sheet collides with a previously printed sheet, the
force of collision may pull the incoming media sheet out of a media
transport device to result in either a moderate or significant
misalignment of the incoming sheet. The misalignment in some cases
causes a paper jam. If the trailing edge curl of the previously
printed sheet is not so severe that collision with by an incoming
sheet grossly misaligns the incoming media sheet, there still may
be sufficient force on the incoming media sheet such that an x- and
y-alignment as well as a z-axis rotation of the incoming media
sheet is impacted; which again may result in a paper jam, or may
have some other negative impact on job quality.
[0016] Yet another complication is that curled media sheets do not
lay flat when stacked and thus create air cushions between sheets
in a stack. This trapped air cushion lowers the sheet-to-sheet
friction such that media sheets slide more easily relative to one
another, impacting the ability to maintain stack alignment. The air
cushions also increase the stack height reducing the capacity of
the media support device.
[0017] Yet another complication is the alignment of incoming media
sheets. For example, in some devices, a y-alignment, or an
alignment along a transport direction of the media is performed by
an alignment wall. As a media transport device releases the
incoming media sheet, kinetic energy in the media sheet may cause
the sheet to bounce off the alignment wall, pushing the media sheet
away from the alignment wall. Such a pushing away may result in a
misalignment in that direction or even a curl of the media sheet
near the alignment wall.
[0018] Finishing systems have been devised to address incoming
media sheet alignment. For example, in some finishing systems an
incoming media sheet is ejected onto a previously accumulated
stack. Before and during the ejection, the device may use a tapping
action on two parallel edges of the media sheet to move the media
sheet into the desired position and alignment in a single
direction. Before or after this first alignment, a second operation
is carried out to align the stack/sheet in a second direction.
While this process may work for relatively flat media, it does not
address the complications mentioned above that arise when dealing
with an undried or partially-dried, and therefore non-flat, media.
In other words, the present systems do not account for the effects
of page curl, i.e., undried or partially-dried media, nor do they
accommodate alignment of the undried or partially-dried media,
which undried or partially-dried media have characteristics that do
not lend well to the alignment described above. In fact, some
finishing systems, rather than executing finishing operations on
undried or partially-dried printing media, first dry the media and
then perform the finishing operations. However, such drying
equipment is costly and further lengthens the time to output of a
job.
[0019] The present specification describes a system and method for
preventing media misalignment during accumulation, particularly an
undried or partially-dried media. Specifically, the present
specification describes a device and method for controlling and
maintaining an x-direction alignment and a y-direction alignment of
a sheet printed by a fluid printing system. Doing so simplifies
post-printing value-added operations such as stack alignment,
stapling, offset, and other finishing operations. The systems and
methods described herein also control edge curl so as to not impact
the transport of an incoming media sheet in the finishing
system.
[0020] The system includes a number of media clamps having multiple
positions to prevent misalignment of an incoming media sheet during
accumulation. The media clamps are in a raised position after a
leading edge of an incoming media sheet has passed over the
trailing edge of the stack region. The media clamps are then
returned to an intermediate or a clamped position after the leading
edge of the incoming media sheet has passed the media clamp to
maintain control of the incoming media sheet.
[0021] The present specification also describes a method for
preventing media misalignment of an incoming media sheet during
accumulation. The method includes placing media clamps having
multiple positions in a clamped position until a leading edge of an
incoming media sheet has passed over a trailing edge of a stack
region. The media clamps are then raised after a leading edge of
the incoming media sheet has passed over a trailing edge of a stack
region and then lowered after the leading edge of the incoming
media sheet has passed the media clamp.
[0022] The present specification also describes a system for
preventing media misalignment of an incoming media sheet during
accumulation. The system includes a number of sets of media clamps
having multiple positions. Each set of media clamps corresponds to
a different media size and/or orientation and maintains alignment
of an incoming media sheet when the incoming media sheet is of a
corresponding size. When maintaining the alignment, a set of media
clamps 1) are in a clamped position until a leading edge of the
incoming media sheet has passed over a stack region of a media
support device, 2) are in a raised position after the leading edge
of the incoming media sheet has passed over a trailing edge of the
stack region, 3) move to an intermediate position after the leading
edge of the incoming sheet has passed by the media clamp and 4)
return to the clamped position either before or during the
secondary alignment process (y-alignment). The set of media clamps
are in a raised position when an incoming media sheet is not of a
corresponding media size.
[0023] Certain examples of the present disclosure are directed to
systems and methods for preventing misalignment of an incoming
media sheet that 1) prevents page jams; 2) prevents page defects
such as bent or rolled edges or corners: 3) accommodates finishing
for undried or partially-dried incoming media sheets; 4) maintains
page alignment in a media support device; 5) simplifies
post-printing operations; and 6) addresses page curl and cockle as
well as alignment for a variety of media sizes. However, it is
contemplated that the devices and methods disclosed herein may
prove useful in addressing other deficiencies in a number of
technical areas. Therefore the systems and devices disclosed herein
should not be construed as addressing just the particular elements
or deficiencies discussed herein.
[0024] As used in the present specification and in the appended
claims, the term "stack region" refers to a portion of a media
support device defined by where the media is to be accumulated. For
example, the stack region may be a sheet sized portion of a media
support device. The stack region may correspond to the page size
for a particular print media.
[0025] Further, as used in the present specification and in the
appended claims, a "y-direction" refers to a transport direction of
the incoming media sheet. While specific reference is made to the
y-direction, any direction may be implemented as a y-direction.
[0026] Still further, as used in the present specification and in
the appended claims, an "x-direction," "x axis," or similar
terminology refers to a direction or axis that is perpendicular to
the y-direction or y-axis. The x-direction, y-direction, and a
z-direction as well, are indicated in multiple figures.
[0027] Even further, as used in the present specification and in
the appended claims, the term "raised position" refers to any
number of positions that are not a clamped position. Within a
raised position is any number of sub-positions. For example, an
intermediate position is an example of a raised position as is a
high position.
[0028] Yet further, as used in the present specification and in the
appended claims, the term "a number of" or similar language is
meant to be understood broadly as any positive number including 1
to infinity; zero not being a number, but the absence of a
number.
[0029] In the following description, for purposes of explanation,
numerous specific details are set forth in order to provide a
thorough understanding of the present systems and methods. However,
the present apparatus, systems, and methods may be practiced
without these specific details. Reference in the specification to
"an example" or similar language indicates that a particular
feature, structure, or characteristic described in connection with
that example is included as described, but may not be included in
other examples.
[0030] FIGS. 1A-1C are examples of a system (100) for preventing
misalignment of an incoming media sheet (102), according to one
example of the principles described herein. The system (100)
includes a number of media clamps (104) having multiple positions
to prevent misalignment of an incoming media sheet (102) during
accumulation. As used in the present specification and in the
appended claims, the media sheet (102) may be any type of suitable
sheet or roll material, such as paper, card stock, transparencies,
polyester, plywood, foam board, fabric, canvas, and the like. In
another example, the print medium may be an edible substrate. Still
further, in some examples, the media sheet (102) is an undried or
partially-dry media sheet (102) meaning that the printing fluid on
the print media (102) may still be wet, but may be dry enough so as
to not smear or smudge. As described above, the systems (100) and
methods described herein allow for efficient and effective handling
of such partially-dry media sheets (102) where other finishing
systems are not capable of so doing.
[0031] In the examples depicted in FIGS. 1A-1C an existing stack
(106) of media is present. The size and shape of the stack (106) of
media defines a stack region (114) of the media transport device.
For example, the size of the media sheets in the stack (106) may
define the stack region (114) that is used as a point of reference
to determine when to raise and lower the media clamps (104). In
other words, the stack region (114) is the region of a media
support assembly that does or does not include an existing stack
(106) and is the size of the incoming media sheet (102).
Accordingly, the stack region (106) is dependent upon the incoming
media sheet (102) size and each media sheet size has a
corresponding stack region (114). As used in the present
specification and in the appended claims, the trailing edge (108)
of the stack (106), or more specifically the stack region (114), is
the distal portion of the stack (106) or stack region (114) with
respect to the sheet transport direction (112). The trailing edge
(108) of the stack region (114) is the first part of the stack
region (114) that an incoming sheet (102) interacts with. While the
figures describe the incoming media sheet (102) as being added to
an existing stack (106), in some examples, the incoming media sheet
(102) may be the first sheet of a stack (106). In this example, the
system (100) works similarly to how it would if there is an
existing stack (106).
[0032] As depicted in FIGS. 1A-1C, the incoming media sheet (102)
may be transported to be deposited on an existing stack (106) in a
sheet transport direction (112). In the present specification, the
sheet transport direction (112) may be a y-direction as indicated
in the coordinate graphic. While the present specification
describes the sheet transport direction (112) as a y-direction, the
sheet transport direction (112) may be any direction. For the
present specification, the directions noted are based on the
coordinate system; however, other coordinate systems may be
used.
[0033] The system (100) includes a number of media clamps (104),
one of which is indicated in FIG. 1A. The media clamps (104) are
devices that work to provide a clear path for an incoming sheet of
media (102) and that control page curl within the stack (106) of
media. The media clamps (104) function to compress the trailing
edge (108) of a stack (106) of media sheets against a media support
device. For example, as described above, sheets of the stack (106)
may exhibit page curl due to the effects of deposition of a
printing fluid as described above. Unchecked page curl (110-1) may
impact the reception of an incoming media sheet (102). While the
figures of the present specification illustrate curl (110) in a
particular direction, i.e., an upward curl (110), the curl (110)
can be in any direction, such as a downward curl.
[0034] As can be seen in FIG. 1A, an incoming media sheet (102) fed
in sheet transport direction (112) may collide with a previously
printed sheet having unchecked page curl (110-1). This collision of
the incoming media sheet (102) with the sheet exhibiting page curl
(110-1) may cause the page curl to roll over onto itself causing a
defect identified as roll over. An example of page roll over is
depicted in FIG. 1B. Page roll over may impact the subsequent
receipt of incoming media sheets (102) and may affect the quality
of the print job on the sheet with the unchecked page curl (110-1).
Still further, the unchecked page curl (110-1) may cause
misalignment of the incoming media sheet (102) by either partially
or fully removing the incoming media sheet (102) from a media
transport assembly that is positioning the incoming media sheet
over the stack (106). Such removal from the media transport
assembly may result in a misalignment of the incoming media sheet
(102) which could cause a paper jam in the corresponding
device.
[0035] To prevent this misalignment due to page curl, the media
clamp (104) may be in a clamped position until a leading edge of
the incoming media sheet (102) has passed over the trailing edge
(108) of the stack region (114). Doing so may reduce the page curl.
In other words, media clamps (104) generate a reduced page curl
(110-2) in a sheet of the stack (106). A reduced page curl (110-2)
has less, if any, impact on the incoming media sheet (102) as the
media sheet with the reduced page curl (110-2) has been moved out
of the transport path of the incoming media sheet (102). The media
clamps (104) also serve to compress the stack (106), removing
extraneous air cushions between sheets of the stack (106) reducing
the propensity for misalignment of the stack (106).
[0036] While FIG. 1A depicts the media clamps (104) as being
proximate to the trailing edge (108) of the stack region (114), the
media clamps may be at other positions. For example, as depicted in
FIG. 8, the media clamps (104) may be positioned at the trailing
edge (108) so as to exert pressure on the corners of the stack
(106). Still further, the media clamps (104) or additional media
clamps (104) may be positioned at various points along the sheet
transport direction (112) or other direction to accommodate curl or
cockle in other portions of an incoming media sheet (102) and to
further ensure proper alignment of the stack (106).
[0037] After, the incoming media sheet (102) has passed over the
trailing edge (108) of the stack region (114), the media clamps
(104) are moved to a raised position as depicted in FIG. 1B. As can
be seen in FIG. 1B, and unchecked page curl (110-1) can roll over
on itself due to frictional forces between the sheet with the
unchecked page curl (110-1) and the incoming media sheet (102).
However, due to the media clamp (104) previously being in a clamped
position as indicated in FIG. 1A, the incoming media sheet (102)
can pass over the reduced page curl (110-2) uninterrupted such that
an incoming media sheet (102) can pass across the stack (106)
without any complication. In the raised position, the media clamps
(104) do not interfere with the transport of the incoming media
sheet (102) over the stack (106). While FIG. 1B indicates the
movement of the media clamps (104) between the clamped and raised
positions as a pivot motion, the media clamps (104) may be raised
and lowered via any form of movement such as vertical translation
in a z-direction, or rotation in an x-direction. As the media
clamps (104) move, the system (100) also includes a component for
moving the media clamps (104). In some examples, this may be a
motor that is coupled to a media clamp (104). In other examples,
the movement of a media transport assembly may cause the media
clamps (104) to raise and lower.
[0038] At some point after the alignment of the incoming media
sheet (102), the media clamps (104) are returned to the clamped
position as indicated in FIG. 1A to maintain an alignment, and
control, of the incoming media sheet (102). For example at some
point after the leading edge of the incoming media sheet (102) has
passed the media clamp (104) in the sheet transport direction (FIG.
1A, 112) and after an x-direction alignment, the media clamps (104)
are returned to the clamped position in preparation for another
sheet reception cycle. In other words, the media clamps (104) cycle
between a clamped position and a raised position as each incoming
media sheet (102) of a job is received. Accordingly, for a printing
device that prints at a rate of 40 pages per minute, the media
clamps (104) may follow this cycle of raising and clamping 40 times
in a minute.
[0039] While FIGS. 1A and 1B exhibit two positions, a clamped
position and one raised position, a media clamp (104) may move
between multiple raised positions. For example, as depicted in FIG.
1B, after the leading edge of the incoming media sheet (102) has
passed over the trailing edge (108) of the stack region, the media
clamps may be in a first raised position, i.e., a high position.
Once the leading edge of the incoming media sheet (102) has passed
beyond the media clamp (104) in a sheet transport direction (FIG.
1A, 112), the media clamp (104) may be placed in a second raised
position, i.e., lowered to an intermediate position as indicated in
FIG. 1C. The intermediate position may be raised above the media
stack (106) by a distance that is less than the high raised
position. For example in the intermediate position, the media
clamps (104) may be between 5 and 7 millimeters above the stack
(106). In this intermediate position, the media clamps (104) exert
a reduced amount of pressure on the stack (106) as compared to when
in the clamped position depicted in FIG. 1A.
[0040] This reduced amount of pressure and reduced height reduce
the likelihood of stubbing and rolling over of the stack (106), but
allow for movement of the incoming media sheet (102). Such a
reduced height and pressure may be maintained during certain
operations. For example, the media clamps (104) may remain in this
intermediate position during an x-direction alignment of the
incoming media sheet (102). In the present specification, an
x-direction is perpendicular to the sheet transport direction (FIG.
1A, 112) or y-direction and may be into the page. After this
x-direction alignment, the media clamps (104) may be lowered to the
clamped position as depicted in FIG. 1A. When in the clamped
position, or prior to returning to the clamped position, the
incoming media sheet (102) may be aligned in a y-direction. If the
media clamps (104) are not yet in the clamped position as the
y-direction alignment begins, the media clamps (104) may be in the
clamped position by the end of the y-direction alignment. While in
the clamped position, the system (100) maintains alignment, and
control, of the incoming media sheet (102) relative to the stack
(106) and prepares for the reception of a new incoming media sheet
(102).
[0041] The system (100) described herein includes media clamps
(104) movable between multiple positions or heights allowing for
enhanced finishing by addressing the difficulties in finishing
undried or partially-dried incoming media sheets (102). More
specifically, the media clamps (104) allow for accommodating
undried or partially-dried incoming media sheets (102) that may
have a greater propensity for misalignment and that exhibit page
curl, which page curl may interrupt the media transport. While
specific reference is made to the system (100) operating on
partially-dried media, the system (100) may also be implemented to
receive fully-dried media.
[0042] FIG. 2 is a flowchart of a method (200) for preventing media
misalignment during accumulation, according to one example of the
principles described herein. According to the method (200), media
clamps (FIG. 1, 104) having multiple positions are placed (block
201) into a clamped position until a leading edge of the incoming
media sheet (FIG. 1, 102) has passed over a trailing edge (FIG. 1,
108) of the stack region (FIG. 1, 114). In other words, before the
incoming media sheet (FIG. 1, 102) is to be deposited on the stack
(FIG. 1, 106), the media clamps (FIG. 1, 104) are in a down, or
clamped, position. This position is indicated in FIG. 1A. In the
clamped position the media clamps (FIG. 1, 104) maintain an
x-direction alignment, a y-direction alignment, and z-axis
rotational alignment of the stack (FIG. 1, 106) of media. In other
words, while in the clamped position, the sheets in the stack (106)
are prevented from moving relative to one another and therefore are
in proper alignment for subsequent operations or for movement to
another section of the printing system. While in the clamped
position, the media clamps (FIG. 1, 104) are also compressing air
cushions that may be present between individual sheets in the stack
(FIG. 1, 106). As described above, these air cushions reduce
surface friction between adjacent sheets. As the friction serves to
maintain an alignment of the stack (FIG. 1, 106), a reduction in
the friction increases the likelihood of a misalignment.
[0043] Once the leading edge of the incoming media sheet (FIG. 1,
102) has passed over the trailing edge (FIG. 1, 108) of the stack
region (FIG. 1, 114), the media clamps (FIG. 1, 104) are raised
(block 202). In other words, after the leading edge of the incoming
media sheet (FIG. 1, 102) has passed over the trailing edge (FIG.
1, 108), but before coming into contact with the media clamp (FIG.
1, 104), the media clamp (FIG. 1, 104) is moved out of the
transport path of the incoming media sheet (FIG. 1, 102). In this
raised position the media clamps (FIG. 1, 104) do not interfere
with the continual transport of the incoming media sheet (FIG. 1,
102). As the media clamps (FIG. 1, 104) are raised after the
leading edge has passed over the trailing edge (FIG. 1, 108), the
leading edge of the incoming media sheet (FIG. 1, 102) has already
passed over the curled portion of the existing sheet and therefore
the curled portion of the page is less likely to impact the
transport of the incoming media sheet (FIG. 1, 102).
[0044] Once the incoming media sheet (FIG. 1, 102) has passed by
the media clamp (FIG. 1, 104) in a sheet transport direction (FIG.
1, 112), the media clamps (FIG. 1, 104) are lowered (block 203) to
a clamped position to align the incoming media sheet (FIG. 1, 102)
with the stack (FIG. 1, 106). This lowering (block 203) of the
media clamps (FIG. 1, 104) to the clamped position may come after a
number of other operations. For example, after raising (block 202)
the media clamps (FIG. 1, 104) to a high raised position, the media
clamps (FIG. 1, 104) may be lowered to an intermediate position
during x-alignment, and then lowered (block 203) to the clamped
position during a y-direction alignment.
[0045] In returning to the clamped position, the system (FIG. 1,
100) is prepared to begin another sheet reception cycle including
raising the media clamps (FIG. 1, 104) upon arrival of a new
incoming media sheet (FIG. 1, 102). Returning to the clamped
position also maintains alignment of the stack (FIG. 1, 106) which
now includes the just received media sheet (FIG. 1, 102).
[0046] The method as described herein may allow for incoming media
sheet (FIG. 1, 102) alignment within a stack (FIG. 1, 106) while
addressing the complications that arise from processing certain
media types such as undried or partially-dried media. For example,
the media clamps (FIG. 1, 104) by clamping previous to the arrival
of an incoming media sheet (FIG. 1, 102) suppress the page curl of
the stack (FIG. 1, 106) so as to not interfere with the transport
of the incoming media sheet (FIG. 1, 102). Thus, the system (FIG.
1, 100) reduces the effects of page curl that are likely to occur
when using a printing fluid and improves the execution of finishing
operations on such undried or partially-dried media.
[0047] FIG. 3 is a top view of a printing system (100) for
preventing media misalignment during accumulation, according to
another example of the principles described herein. In some
examples, the system (100) includes a number of sets of media
clamps (104). The different sets of media clamps (104) correspond
to different media sizes. For example, a first set of media clamps
(104-1) may pertain to a first media size (316-1). Similarly, a
second set, third set, and fourth set of media clamps (104-2,
104-3, 104-4) pertain to a second, third, and fourth media (316-2,
316-3, 316-4) size, respectively. As indicated in FIG. 3, a set of
media clamps (104-1) may include multiple media clamps (104).
Examples of different media sizes include letter/A4 in different
orientations, legal, and ledger/A3. The different media clamps
(104) in addition to supporting different media sizes also support
different media orientations. For example, as depicted in FIG. 3,
the first set of media clamps (104-1) may be used to manage the
alignment of letter/A4 size media in a landscape orientation. The
second set of media clamps (104-2) may be used to manage the
alignment of letter/A4 size media in a portrait orientation. The
third set of media clamps (104-3) may be used to manage the
alignment of legal size media in a portrait orientation. The fourth
set of media clamps (104-4) may be used to manage the alignment of
ledger/A3 size media in a portrait direction.
[0048] Accordingly, each set of media clamps (104) can manage the
alignment of an incoming media sheet (FIG. 1, 102) that corresponds
to the size (316) and location of the media clamps (104). As
described above managing the alignment includes placing the
corresponding media clamps (104) in a clamped position until a
leading edge of the media sheet (FIG. 1, 102) has passed over the
stack region (FIG. 1, 114) of the media support device, being in a
raised position after the leading edge of the incoming media sheet
(FIG. 1, 102) has passed over a trailing edge (FIG. 1, 108) of the
stack region (FIG. 1, 114), and returning to the clamped position
after the leading edge of the incoming media sheet (FIG. 1, 102)
has passed the corresponding media clamps (104) to align the
incoming media sheet (FIG. 1, 102) relative to the stack region
(FIG. 1, 114). Using multiple sets of media clamps (104) allows for
the alignment of media sheets of varying size.
[0049] As described above, the media clamps (104) maintain the
alignment of the media stack (FIG. 1, 106) and also prevent page
curl in the media stack (FIG. 1, 106). In receiving different media
sizes (316), different amounts of pressure may be exerted upon the
media stack (FIG. 1, 106) in order to reduce page curl.
Accordingly, depending upon the application, media clamps (104) may
be weighted to exert a sufficient force on the media stack (FIGS.
1, 106) to 1) prevent page curl and 2) to maintain an x-direction
and a y-direction alignment of the media stack (FIG. 1, 106).
[0050] Within a set of media clamps (104) each individual media
clamp (104) may be individually controlled while moving down to the
clamped position to allow equal contact of the media clamps (104)
within a set on at least one of a media stack (FIG. 1, 106) and a
media support assembly. Doing so allows both media clamps (104)
within a set to rest on the stack (FIG. 1, 106). Having both media
clamps (104) in a set resting on the media sheet (102) ensures one
contact point for each media clamp (104) to prevent sheet movement,
for example during a y-direction alignment.
[0051] In addition to the individual media clamps (104) being
independently controlled each of the sets of media clamps (104) are
also independently controlled. For example, FIG. 4 is a side view
of the printing system (100) of FIG. 3, according to one example of
the principles described herein. In the example of FIG. 4, the
stack (106) can include media sheets of any size (316). When the
media size (316-1) corresponds to a particular set of media clamps
(104-1), that set of media clamps (104-1) is activated to manage
the alignment of any incoming media sheets (FIG. 1, 102) of the
corresponding size (316-1). By comparison, when an incoming media
sheet (FIG. 1, 102) is not of a corresponding media size (316-2,
316-3, 316-4); the corresponding media clamps (104-2, 104-3, 104-4)
are in a raised position. As the media clamps (104) move between
positions, the system (100) also includes a component that
actuates, or engages the media clamps (104). In some examples, the
media clamps (104) are actuated by motors that are coupled to the
media clamps (104). In other examples, the media clamps (104) are
actuated by motion of a media transport assembly.
[0052] FIG. 5 is a flowchart of a method (500) for preventing media
misalignment during accumulation, according to another example of
the principles described herein. According to the method (500) an
intermediate position of the media clamps (FIG. 1, 104) is
calibrated (block 501). Calibrating (block 501) the intermediate
position of the media clamps (FIG. 1, 104) allows for a desired
intermediate height to be set that does not interfere with the
motion of the incoming media sheet (FIG. 1, 102) but that exerts
some pressure during x-direction alignment and prevents some page
curl. During manufacturing process, the manufacturing tolerances
may not be tight enough to ensure a proper intermediate height that
does not interfere with the transport path of incoming media sheets
(FIG. 1, 102). Accordingly, calibrating the intermediate position
ensures the desired intermediate height is set for the media clamps
(FIG. 1, 104). More detail regarding the intermediate position
calibration is given below in connection with FIGS. 7A-7E.
[0053] The method (500) also includes receiving (block 502) at
least a partially-dry incoming media sheet (FIG. 1, 102). For
example, the system (FIG. 1, 100) may receive an undried media
sheet or a partially-dried media sheet. The undried or
partially-dry incoming media sheet (FIG. 1, 102) may have curl in
any direction such as an upward curl or a downward curl. As
described above previous systems may dry the incoming media sheet
(FIG. 1, 102) completely before performing any finishing operation.
However so doing may elongate the length of time to receive a
finished output as well as increasing the cost, size and complexity
of the system (FIG. 1, 100). Accordingly, the method (500) includes
receiving (block 502) an undried or partially-dry incoming media
sheet (FIG. 1, 102) and performing certain operations to manage the
alignment of such undried or partially-dried media sheets. As used
in the present specification a partially-dried media sheet may be a
media sheet that is sufficiently dry so as to not smear or smudge,
but still contains printing fluid in a liquid form on the surface
of or within the media sheet.
[0054] The media clamps (FIG. 1, 104) are placed (block 503) in a
clamped position until a leading edge of the incoming media sheet
(FIG. 1, 102) passes over a trailing edge (FIG. 1, 108) of the
stack region (FIG. 1, 114). This may be performed as described
above in connection with FIG. 2. The media clamps (FIG. 1, 104) are
then raised (block 504) after a leading edge of the incoming media
sheet (FIG. 1, 102) has passed over a trailing edge (FIG. 1, 108)
of the stack region (FIG. 1, 114). This may be performed as
described in connection with FIG. 2.
[0055] The media clamps (FIG. 1, 104) are then lowered (block 505)
to an intermediate position during a remaining transport and an
x-direction alignment of the incoming media sheet (FIG. 1, 102).
For example, as depicted in at least FIGS. 1A-1C, the x-direction
may be perpendicular to the media transport direction (FIG. 1,
112). Accordingly, the system (FIG. 1, 100) may include a component
that aligns the media sheets in a direction perpendicular to the
media transport direction (FIG. 1, 112) such that the media sheets
are properly aligned. The media clamps (FIG. 1, 104) may be in an
intermediate position to reduce the likelihood of stubbing and
rolling over of the stack and offer an amount of resistance, but
not so much as to impede the x-direction alignment of the incoming
media sheet (FIG. 1, 102). For example, as described above, higher
friction may be beneficial to maintain the alignment of the stack
(FIG. 1, 106), but too high a friction may impede certain alignment
processes. Accordingly, while in an intermediate position, the
media clamps (FIG. 1, 104) maintain the alignment of the incoming
media sheet (FIG. 1, 102) without providing such a high friction as
to impede the x-direction alignment.
[0056] During a y-direction alignment of the incoming media sheet
(FIG. 1, 102), the media clamps (FIG. 1, 104) are lowered (block
506) to a clamped position. In some examples, the media clamps
(FIG. 1, 104) may be kept in the intermediate position until after
the y-direction alignment has started, but are lowered before the
y-direction alignment is completed. Doing so may prevent
misalignment of the incoming media sheet (FIG. 1, 102) due to the
y-direction alignment process. For example, FIG. 6 is a side view
of a media clamp (104) for preventing media misalignment during
accumulation, according to one example of the principles described
herein. In this example, the y-direction alignment occurs as a
media transport assembly causes the incoming media sheet (102) to
contact a y-direction alignment wall (614) which aligns the stack
(106) in the y-direction. However, due to the kinetic energy of the
incoming media sheet (102) as imparted by the media transport
assembly, the incoming media sheet (102) may rebound off the
y-alignment wall (614) which may cause misalignment of the incoming
media sheet (102) in the y-direction, or may cause an additional
curl (110-3) at a portion of the incoming media sheet (102) that
contacts the y-alignment wall (614) as indicated by the dashed
line. Accordingly, by lowering the media clamp (104) into the
clamped position during y-alignment as depicted in FIG. 6, the
pressure of the media clamp (104) prevents the rebound back of the
incoming media sheet (102) and hinders the creation of curl (110-3)
at the alignment wall (614).
[0057] Returning to FIG. 5, Table (1) below provides the
positioning of the media clamps (FIG. 1, 104) at different stages
of a finishing operation as described, in part, in connection with
FIG. 5. In this example, the incoming media size (FIG. 3, 316) is a
Letter/A4 sized media sheet in a landscape orientation. In other
words, just the media clamps (FIG. 3, 104-1) pertaining to the
landscape/A4 landscape orientation size (FIG. 3, 316-1) media sheet
are activated and all others are in a raised position.
TABLE-US-00001 TABLE 1 Incoming Media Sheet Position Media Clamp
Position Incoming sheet (FIG. 1, 102) not over Down the stack
region (FIG. 1, 106) until just over the trailing edge (FIG. 1,
108). Leading edge of the incoming sheet Up (FIG. 1, 102) passed
over the trailing edge (FIG. 1, 108) of the stack region (FIG. 1,
106). Incoming sheet (FIG. 1, 102) past the Intermediate media
clamp (FIG. 1, 104). x-direction alignment of the incoming
Intermediate sheet (FIG. 1, 102). y-direction alignment of the
incoming May be a combination of both sheet (FIG. 1, 102).
Intermediate and Down Subsequent finishing operations Up Moving to
other section of printing device Up
[0058] FIGS. 7A-7E are diagrams of the method for calibrating a
media clamp (104), according to one example of the principles
described herein. First, as depicted in FIG. 7A, the media clamp
(104) is lowered to an elevation that is lower than a media support
device (718). In this example, the media clamp (104) is positioned
to the side of the media support device (718) as depicted in FIG.
7B.
[0059] Next, as depicted in FIG. 7B, the media support device (718)
is moved, or translated towards the media clamp (104) as indicated
by the arrow (720). A component of the system (FIG. 1, 100) then
determines if there is contact between the media support device
(718) and the media clamp (104). For example, when the media clamp
(104) is lower than the media support device (718) as depicted in
FIG. 1A, a translation of the media support device (718) would
cause the media support device (718) to impact the media clamp
(104). Such a contact results in a spike in the motor torque that
moves the media support device providing detection of the
contact.
[0060] If contact is detected, the media clamp (104) is then
incrementally raised as indicated in FIG. 7C and the media support
device (718) is again translated towards the media clamp (104) as
indicated in FIG. 7B. In the setting depicted in FIG. 7C, contact
would be detected and the media clamp (104) would again be raised
in an incremental fashion to a position as indicated in FIG. 7D
which would indicate no contact between the media clamp (104) and
the media support device (718). Once no contact is detected between
the media support device (718) and the media clamp (104), the
intermediate position is set as an additional predetermined
distance from the point of no contact as depicted in FIG. 7E. The
operation depicted in FIGS. 7A-7E may be performed for all the
media clamps (104).
[0061] FIG. 8 is a diagram of a media clamp (104), according to
another example of the principles described herein. In this
example, the media clamp (104) may be designed so as to align and
exert pressure on the trailing edge (108) of the stack (106), not
just proximate to the trailing edge (108). Doing so may further
reduce the page curl and reduce the impact of any page curl on the
transport of the incoming media sheet (102). Still further, the
media clamp (104), or other media clamps (104) may be sized or
placed to exert pressure over desired locations and area sizes of
the stack (106).
[0062] Certain examples of the present disclosure are directed to
systems and methods for preventing misalignment of an incoming
media sheet that 1) prevents page jams; 2) prevents page defects
such as bent or rolled edges or corners: 3) accommodates finishing
for undried or partially-dried incoming media sheets; 4) maintains
page alignment in a media support device; 5) simplifies
post-printing operations; and 6) addresses page curl and cockle as
well as alignment for a variety of media sizes. However, it is
contemplated that the devices and methods disclosed herein may
prove useful in addressing other deficiencies in a number of
technical areas. Therefore the systems and devices disclosed herein
should not be construed as addressing just the particular elements
or deficiencies discussed herein.
[0063] The preceding description has been presented to illustrate
and describe examples of the principles described. This description
is not intended to be exhaustive or to limit these principles to
any precise form disclosed. Many modifications and variations are
possible in light of the above teaching.
* * * * *