U.S. patent application number 11/269313 was filed with the patent office on 2007-05-10 for apparatus for varying pressure roll nip force.
This patent application is currently assigned to Lexmark International, Inc.. Invention is credited to Larry W. Acton, William M. Connors, Daniel R. Gagnon, Herman A. Smith.
Application Number | 20070102873 11/269313 |
Document ID | / |
Family ID | 38002945 |
Filed Date | 2007-05-10 |
United States Patent
Application |
20070102873 |
Kind Code |
A1 |
Acton; Larry W. ; et
al. |
May 10, 2007 |
Apparatus for varying pressure roll nip force
Abstract
An apparatus for varying nip pressure in a media feedpath
including a feed roller and a pressure roller defining a feed nip
there between includes a rotatable cam having a preselected
eccentric path when rotated, a first pivotable linkage pivotally
engaging the rotatable cam, a second pivotable linkage, a biasing
member operably interconnecting the first and second pivotal
linkages for providing a biasing force on the pressure roller. The
pressure roller is rotatably connected to the second linkage
opposite the biasing member, wherein rotation of the cam varies the
biasing force provided by the biasing member on the pressure
roller.
Inventors: |
Acton; Larry W.; (London,
KY) ; Connors; William M.; (Lexington, KY) ;
Gagnon; Daniel R.; (Harrodsburg, KY) ; Smith; Herman
A.; (Winchester, KY) |
Correspondence
Address: |
LEXMARK INTERNATIONAL, INC.;INTELLECTUAL PROPERTY LAW DEPARTMENT
740 WEST NEW CIRCLE ROAD
BLDG. 082-1
LEXINGTON
KY
40550-0999
US
|
Assignee: |
Lexmark International, Inc.
|
Family ID: |
38002945 |
Appl. No.: |
11/269313 |
Filed: |
November 8, 2005 |
Current U.S.
Class: |
271/273 |
Current CPC
Class: |
B65H 2511/224 20130101;
B65H 5/062 20130101 |
Class at
Publication: |
271/273 |
International
Class: |
B65H 5/02 20060101
B65H005/02; B65H 5/04 20060101 B65H005/04 |
Claims
1. An apparatus for varying nip pressure in a media feedpath
including a feed roller and a pressure roller defining a feed nip
therebetween, comprising: a rotatable cam having a preselected
eccentric path when rotated; a first pivotable linkage pivotally
engaging said rotatable cam; a second pivotable linkage; a biasing
member operably interconnecting said first and second pivotal
linkages for providing a biasing force on said pressure roller;
and, said pressure roller rotatably connected to said second
linkage opposite said biasing member; wherein rotation of said cam
varies the biasing force provided by said biasing member on said
pressure roller.
2. The apparatus of claim 1 wherein said cam has an eccentric
shape.
3. The apparatus of claim 2 further comprising a rotatable shaft
operably connected to said cam.
4. The apparatus of claim 1 wherein said first linkage pivots about
a first linkage pivot point as said cam rotates.
5. The apparatus of claim 1 wherein rotation of said cam the loads
and unloads said biasing member connected to said first linkage and
said second linkage as said cam is rotated.
6. The apparatus of claim 5 wherein said pressure roller exerts
greater force on said feed roll as said biasing member is loaded
and exerts lesser force on said feed roll as said biasing member is
unloaded.
7. The apparatus of claim 1, wherein said pressure roller comprises
a plurality of pressure rollers.
8. A variable pressure roll linkage for media feedpath, comprising:
an elastic member; a first linkage; a feed drive roller and a
pressure roller defining a nip therebetween; a second linkage with
said pressure roller operably connected to said second linkage with
said first linkage connected to said second linkage by said elastic
member; and, a cam moveable about a preselected profile engaging
said first linkage wherein movement of said cam loads and unloads
said elastic member and causes translation of said pressure roller
at said nip.
9. The variable pressure roll linkage of claim 8, wherein said
pressure roller is translatable toward and away from said feed
drive roller.
10. The variable pressure roll linkage of claim 8 wherein rotation
of said cam pivots said first linkage.
11. The variable pressure roll linkage of claim 8, said elastic
member further comprising a spring.
12. The variable pressure roll linkage of claim 8 wherein
application of tension to said elastic member increases force of
said pressure roll toward said drive roll.
13. The variable pressure roll linkage of claim 12, said
application of tension is caused by movement of said cam.
14. The variable pressure roll linkage of claim 8, said pressure
roll further comprising a plurality of pressure rolls mounted on a
pressure roll shaft and said drive roller comprising at least one
drive roller mounted on a drive roll shaft.
15. A pressure roll linkage for applying variable pressure to a
pressure roll, comprising: a pivotable follower plate; said
follower plate engaged by a mover to cause pivotal movement of said
follower plate; a pressure roller housing adjacent said follower
plate, said pressure roller housing having at least one pressure
roller; and, a biasing member having a first portion and a second
portion, said first portion connected to said follower plate and
said second portion connected to said pressure roller housing;
wherein actuation of said mover varies pressure applied by said
pressure roller.
16. The pressure roll linkage of claim 15 wherein said follower
plate pivots in a first direction and said pressure roller housing
pivots in a second opposite direction when loading said biasing
member.
17. The pressure roll linkage of claim 15, said pressure roller
moving toward and away from a drive roll when said mover is
actuated and deactuated.
18. The pressure roll linkage of claim 15, said biasing member
being a spring which is tensioned and untensioned as said mover is
actuated and deactuated.
19. The pressure roll linkage of claim 15, said linkage positioned
in a printer feedpath.
20. The pressure roll linkage of claim 15, said linkage positioned
in a scanner auto-document feeder feedpath.
21. The pressure roll linkage of claim 15 said mover being an
eccentric cam.
22. A variable force pressure roll linkage, comprising: a media
feedpath; a drive roller located along said media feedpath; a
biasable idler roller rotatably disposed opposite and biased toward
said drive roller and forming a nip therebetween for feeding media;
and, a variable force means which decreases biasing force on said
idler roller during media exit from said nip.
23. A variable force pressure roll linkage, comprising: a media
feedpath; a drive roller located along said media feedpath; an
idler roller disposed opposite and biased toward said drive roller;
a first linkage and a second linkage connected by a biasing member;
said idler roller rotatably connected to said second linkage; and,
motion means operably coupled to said first linkage for varying
force on said idler roller during media feed.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] None.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] None.
REFERENCE TO SEQUENTIAL LISTING, ETC.
[0003] None.
BACKGROUND
[0004] 1. Field of the Invention
[0005] The present invention relates generally to media feed
mechanisms, and more particularly to a media feed mechanisms in
printing and/or scanning mechanisms.
[0006] 2. Description of the Related Art
[0007] All-in-one machines typically perform functions such as
printing, scanning, copying, and faxing in either a stand alone
fashion or in conjunction with a personal computer and define a
growing market for peripheral devices. These devices eliminate
clutter in a business or home office by combining the desirable
functionality of various machines into a single unit, while
maintaining an affordable cost. Various all-in-one machines
currently in the marketplace use thermal inkjet technology as a
means for printing received fax documents, original documents, and
copied or scanned images or text. Thermal inkjet printing devices
utilize consumable inkjet cartridges in fluid communication with a
printhead to record text and images on a print media. The printhead
typically moves on a carriage relative to the media path and a
control system activates the printhead to selectively eject ink
droplets onto the print media.
[0008] Scanners are used to scan a target image and create scanned
image data which can be displayed on a computer monitor, used by a
computer program, can be printed, or can be faxed, etc. Scanned
data may be saved to memory or a magnetic or optical drive, or
other fixed or removable memory device. Scanning devices may be
packaged in a stand-alone housing or as part of the all-in-one
device, as described herein, including a printing module to perform
scanning as well as standard copying functions.
[0009] Scanners typically include a housing aperture defined by an
edge wherein a platen is located. A target document is positioned
on the platen for scanning of the text or image by a scanbar.
Depending on the positioning of the scanbar relative to the platen,
the platen may be transparent where the scanbar is beneath the
platen or may be solid where the scanbar is above the platen. For a
typical flatbed scanner, the scanbar will be below the platen,
which will have a transparent section to allow for the scan
operation.
[0010] The scanner may also include an automatic document feeder
(ADF) to automatically and sequentially feed a plurality of
documents to a scan module. The ADF typically comprises a feed tray
and an input device which feeds a single sheet from the stack of
media on the feed tray into the ADF media path. The single sheet of
media passes the reading position where the media is illuminated
and image data is created by the scanbar representing images on the
media. The media then passes from the ADF to a stacking tray where
the media remains until all of the media from the feed tray has
been scanned and is removed from the stacking tray at the output
side of the ADF.
[0011] In either printing or ADF scanning, a printing medium or
original document is transported by a feeding mechanism. The
transport mechanism includes at least a pressure roller and a feed
roll or driving roll. The pressure roll or idler roll forces the
media against the feed roll during ADF scanning or printing. When
in contact with the feed roll, the media is advanced for printing
or scanning before engaging an exit roll. Prior art devices place a
constant and continuous bias on the pressure roller in order to
maintain engagement of the pressure roller and feed roll.
[0012] For ease of description, the following is directed to a
printing mechanism such as an ink-jet printing operation, however,
one of ordinary skill in the art should understand that the
problems associated with prior art transport mechanism may also be
associated with ADF scanners. When the media trailing edge exits
the nip between the feed roll and the pressure roll, the media is
urged forward in a feed direction. This advancement of the media
occurs because a downward force of the pressure roller causes a
tangential force having a component in the direction of media feed.
The media may advance some undesirable distance corresponding to
the backlash of a gear train driving the feed roller. The result is
that media may advance some distance greater than the intended
amount. The problem worsens when thicker media is utilized. Due to
the over-advancement of the media, the printhead is moved from its
intended position relative to the medium resulting in ink droplets
being deposited inconsistently and reduced print quality. For
example, banding may occur which is undesirable. In the case of ADF
scanning, the media jump can result in scanning quality
defects.
[0013] Given the foregoing, it will be appreciated that an
apparatus is needed which varies the force applied to media
trailing edge moving through a feed nip of a printing or scanning
feedpath to eliminate media jump.
SUMMARY OF THE INVENTION
[0014] The present invention inhibits media jump when media exits
the nip between the pressure roll and the feed roll.
[0015] According to a first embodiment, an apparatus for varying
nip pressure in a media feedpath including a feed roller and a
pressure roller defining a feed nip therebetween, comprises a
rotatable cam having a preselected eccentric path when rotated, a
first pivotable linkage pivotally engaging the rotatable cam, a
second pivotable linkage, a biasing member operably interconnecting
the first and second pivotal linkages for providing a biasing force
on the pressure roller. The pressure roller is rotatably connected
to the second linkage opposite the biasing member, wherein rotation
of the cam varies the biasing force provided by the biasing member
on the pressure roller. The cam has an eccentric shape. A rotatable
shaft is operably connected to the cam. The first linkage pivots
about a first linkage pivot point as the cam rotates. The cam loads
and unloads the biasing member connected to the first linkage and
the second linkage as the cam is rotated. The pressure roller
exerts greater force on the feed roll as the biasing member is
loaded and exerts lesser force on the feed roll as the biasing
member is unloaded. The pressure roller comprises a plurality of
pressure rollers.
[0016] According to a second embodiment, a variable pressure roll
linkage for media feedpath comprises an elastic member, a first
linkage, a feed drive roller and a pressure roller defining a nip
therebetween, a second linkage with the pressure roller operably
connected to the second linkage with the first linkage connected to
the second linkage by the elastic member, a cam moveable about a
preselected profile engages the first linkage wherein movement of
the cam loads and unloads the elastic member and causes translation
of the pressure roller at the nip. The pressure roller is
translatable toward and away from the feed drive roller. Rotation
of the cam pivots the first linkage. The elastic member further
comprises a spring. The application of tension to the elastic
member increases force of the pressure roll toward the drive roll.
The application of tension is caused by movement of said cam. The
pressure roll further comprises a plurality of pressure rolls
mounted on a pressure roll shaft and the drive roller comprises at
least one drive roller mounted on a drive roll shaft.
[0017] According to a third embodiment, a pressure roll linkage for
applying variable pressure to a pressure roll comprises a pivotable
follower plate, the follower plate is engaged by a mover to cause
pivotal movement of said follower plate, a pressure roller housing
is adjacent the follower plate, the pressure roller housing has at
least one pressure roller; a biasing member has a first portion and
a second portion, the first portion is connected to the follower
plate and the second portion is connected to the pressure roller
housing; wherein actuation of the mover varies pressure applied by
the pressure roller. The follower plate pivots in a first direction
and the pressure roller housing pivots in a second opposite
direction when loading the biasing member. The pressure roller
moves toward and away from a drive roll when the mover is actuated
and deactuated. The biasing member is a spring which is tensioned
and untensioned as the mover is actuated and deactuated. The
linkage is positioned in a printer feedpath. Alternatively, the
linkage may be positioned in a scanner auto-document feeder
feedpath. The mover may be an eccentric cam.
[0018] According to a fourth embodiment, a variable force pressure
roll linkage comprises a media feedpath, a drive roller located
along the media feedpath, a biasable idler roller rotatably
disposed opposite and biased toward the drive roller and forming a
nip therebetween for feeding media, and, a variable force means
which decreases biasing force on the idler roller during media exit
from the nip.
[0019] According to a fifth embodiment, a variable force pressure
roll linkage comprises a media feedpath, a drive roller located
along the media feedpath, an idler roller disposed opposite and
biased toward the drive roller, a first linkage and a second
linkage connected by a biasing member, the idler roller rotatably
connected to the second linkage; and, motion means operably coupled
to the first linkage for varying force on the idler roller during
media feed.
[0020] The present invention allows for varying of force on a
pressure roller when a media trailing edge passes a feed nip
thereby inhibiting media jump and printing and scanning
degradation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The above-mentioned and other features and advantages of
this invention, and the manner of attaining them, will become more
apparent and the invention will be better understood by reference
to the following description of embodiments of the invention taken
in conjunction with the accompanying drawings, wherein:
[0022] FIG. 1 is a perspective view of an all-in-one device with
printing component and a scanning component;
[0023] FIG. 2 is a perspective view of the all-in-one device of
FIG. 1 with a cut-away section depicting the printing
components;
[0024] FIG. 3 is a side view of a printing feedpath including an
apparatus for varying pressure roll nip force;
[0025] FIG. 4 is a perspective view of the apparatus for varying
pressure roll nip force;
[0026] FIG. 5 is a side view of the printing feed path and
apparatus of FIG. 3 in a second position;
[0027] FIG. 6 is a perspective view of the apparatus in the second
position shown in FIG. 5;
[0028] FIG. 7 is a perspective view of an alternative all-in-one
device with a C-shaped printing feedpath;
[0029] FIG. 8 is a side view of the print feedpath of FIG. 7;
and,
[0030] FIG. 9 is a side schematic view of a scanner auto-document
feeder having an apparatus for varying pressure roll nip force.
DETAILED DESCRIPTION
[0031] It is to be understood that the invention is not limited in
its application to the details of construction and the arrangement
of components set forth in the following description or illustrated
in the drawings. The invention is capable of other embodiments and
of being practiced or of being carried out in various ways. Also,
it is to be understood that the phraseology and terminology used
herein is for the purpose of description and should not be regarded
as limiting. The use of "including," "comprising," or "having" and
variations thereof herein is meant to encompass the items listed
thereafter and equivalents thereof as well as additional items.
Unless limited otherwise, the terms "connected," "coupled," and
"mounted," and variations thereof herein are used broadly and
encompass direct and indirect connections, couplings, and
mountings. In addition, the terms "connected" and "coupled" and
variations thereof are not restricted to physical or mechanical
connections or couplings.
[0032] In addition, it should be understood that embodiments of the
invention include both hardware and electronic components or
modules that, for purposes of discussion, may be illustrated and
described as if the majority of the components were implemented
solely in hardware. However, one of ordinary skill in the art, and
based on a reading of this detailed description, would recognize
that, in at least one embodiment, the electronic based aspects of
the invention may be implemented in software. As such, it should be
noted that a plurality of hardware and software-based devices, as
well as a plurality of different structural components may be
utilized to implement the invention. Furthermore, and as described
in subsequent paragraphs, the specific mechanical configurations
illustrated in the drawings are intended to exemplify embodiments
of the invention and that other alternative mechanical
configurations are possible.
[0033] The term image as used herein encompasses any printed or
digital form of text, graphic, or combination thereof. The term
output as used herein encompasses output from any printing device
such as color and black-and-white copiers, color and
black-and-white printers, and all-in-one devices that incorporate
multiple functions such as scanning, copying, and printing
capabilities in one device. Such printing devices may utilize ink
jet, dot matrix, dye sublimation, laser, and any other suitable
print formats. The term button as used herein means any component,
whether a physical component or graphic user interface icon, that
is engaged to initiate output.
[0034] Referring now in detail to the drawings, wherein like
numerals indicate like elements throughout the several views, there
are shown in FIGS. 1-9 various aspects of an apparatus for varying
nip pressure in a media feedpath. The apparatus provides various
functions including varying pressure roll force to decrease nip
pressure and therefore substantially eliminate media jump. The
apparatus may be utilized with printing components as well as ADF
scanners.
[0035] Referring initially to FIG. 1, an all-in-one device 10 is
shown having an ADF scanner portion 12 and a printer portion 20,
depicted generally by the housing. The all-in-one device 10 is
shown and described herein, however one of ordinary skill in the
art will understand upon reading of the instant specification that
the present invention may be utilized with a stand alone printer,
copier, ADF scanner, or other device utilizing a media feed system.
The peripheral device 10 further comprises a control panel 11
having a plurality of buttons for making selections. The control
panel 11 may include a graphics display to provide a user with
menus, choices or errors occurring with the system.
[0036] Still referring to FIG. 1, extending from the printer
portion 20 are an input tray 22 at the rear of the device 10 and an
exit tray 24 extending from the front of the device 10. A media
feedpath 21 (FIG. 3) extends between the input tray 22 and output
tray 24. The printer portion 20 may include various types of
printing mechanisms including a laser printing mechanism or an
ink-jet printing mechanism. For ease of description, the exemplary
printer portion 20 is an inkjet printing device.
[0037] Referring now to FIG. 2, an interior cut-away perspective
view of the all-in-one device 10 is depicted. With the interior
shown, the printing portion 20 includes a carriage 26 having a
position for placement of at least one print cartridge 28. FIG. 2
depicts two print cartridges 28 which may be, for instance, a color
cartridge for photos and a black cartridge for text printing. As
one skilled in the art will recognize, the color cartridge may
include three inks, i.e., cyan, magenta and yellow inks.
Alternatively, in lower cost machines, a single cartridge may be
utilized wherein the three inks, i.e., cyan, magenta and yellow
inks are simultaneously utilized to provide the black for text
printing or for photo printing. During advancement media moves from
the input tray 22 to the output tray 24 in a substantially L-shaped
path along the media feedpath 21 beneath the carriage 26 and
cartridges 28. As the media moves into a printing zone, the media
moves in a Y-direction as depicted and the carriage 26 and the
cartridges move in an X-direction which, is transverse to the
movement of the media M.
[0038] Referring again to FIG. 1, the scanner portion 12 generally
includes an ADF scanner 30, a scanner bed 17 and a lid 14 which is
hingedly connected to the scanner bed 17. Beneath the lid 14 and
within the scanner bed 17 may be a transparent platen for placement
and support of target or original documents for manually scanning.
Along a front edge of the lid 14 is a handle 15 for opening of the
lid 14 and placement of the target document on the transparent
platen (not shown). Adjacent the lid 14 is an exemplary duplexing
ADF scanner 30 which automatically feeds and scans stacks of
documents which are normally sized, e.g. letter, legal, or A4, and
suited for automatic feeding. Above the lid 14 and adjacent an
opening in the ADF scanner 30 is an ADF input tray 18 which
supports a stack of target media or documents for feeding through
the auto-document feeder 30. Beneath the input tray 18, the upper
surface of the lid 14 also functions as an output tray 19 for
receiving documents fed through the ADF scanner 30.
[0039] Beneath the ADF scanner 30 is an optical scanning unit
having a plurality of parts which are not shown but generally
described herein. The scanning unit may comprise a scanning motor
and drive (not shown) which connects the scanning motor and a
scanbar 280, shown generally in FIG. 9. The scanbar 280 is driven
bi-directionally along a scanning axis extending in the direction
of the longer dimension of a scanner bed. At least one guide bar
may be disposed within the scanner bed 17 and may extend in the
direction of the scanning axis to guide the scanning bar 280 along
the scanning axis. The scanbar 280 moves along the at least one
guide bar within the scanner bed 17 beneath the platen. The scanbar
280 has a length which extends in the shorter dimension of the
scanning bed. Thus, the scanbar 280 extends across one dimension
and moves in a perpendicular dimension to scan an entire surface
area of the platen during flatbed scanning. Further, the scanbar
280 may be positioned beneath an ADF window for scanning documents
fed through the ADF.
[0040] The scanbar 280 may include a lamp, an image sensor, and a
mirror therein for obtaining a scanned image from a document. The
image sensor may be an optical reduction type image sensor or a
contact image sensor (CIS) as is known in the art. In either event,
the image sensor then determines the image and sends data
representing the image to onboard memory, a network drive, or a PC
or server housing, a hard disk drive or an optical disk drive such
as a CD-R, CD-RW, or DVD-R/RW. Alternatively, the original document
may be scanned by the optical scanning component and a copy printed
from the printer portion 20 in the case of a multi-function
peripheral device 10. The scanbar 280 is generally either an
optical reduction type using a combination of lens, mirror and a
CCD (Charge Coupled Device) array or CIS array. The CCD array is a
collection of tiny, light-sensitive diodes, which convert photons
into electrons. These diodes are called photosites--the brighter
the light that hits a single photosite, the greater the electrical
charge that will accumulate at that site. The image of the document
that is scanned using a light source such as a fluorescent bulb
reaches the CCD array through a series of mirrors, filters and
lenses. The exact configuration of these components will depend on
the model of scanner. Some optical reduction scanners use a three
pass scanning method. Each pass uses a different color filter (red,
green or blue) between the lens and CCD array. After the three
passes are completed, the scanner software assembles the three
filtered images into a single full-color image. Most optical
reduction scanners use the single pass method. The lens splits the
image into three smaller versions of the original. Each smaller
version passes through a color filter (either red, green or blue)
onto a discrete section of the CCD array. The scanner software
combines the data from the three parts of the CCD array into a
single full-color image.
[0041] In general, for inexpensive flatbed scanners CIS arrays are
used in the scanbar. CIS arrays replace the CCD array, mirrors,
filters, lamp and lens with an array of red, green and blue light
emitting diodes (LEDs) and a corresponding array of
phototransistors. The image sensor array consisting of 600, 1200,
2400 or 4800 LEDs and phototransistors per inch (depending on
resolution) spans the width of the scan area and is placed very
close to the glass plate upon which rest the image to be scanned.
Another version of the CIS uses a single set of red, green and blue
LEDS in combination with light pipes to provide illumination of the
material to be scanned. When the image is scanned, the LEDs combine
to provide a white light source. The illuminated image is then
captured by the row of sensors. CIS scanners are cheaper, lighter
and thinner, but may not provide the same level of quality and
resolution found in most optical reduction scanners. Color scanning
is done by illuminating each color type of LED separately and then
combining the three scans.
[0042] Referring now to FIGS. 3-4, exemplary internal components of
a print feedpath 21 of the all-in-one device 10 are depicted in a
side schematic view and perspective view, respectively. Media M is
disposed in the input tray 22, which is the beginning of the
feedpath 21 extending to the exit tray 24 where media M is
collected after printing. A frame 52 is located within the housing
of the all-in-one device 10 is depicted generally and extends
vertically adjacent the variable pressure roll linkage 50. The
frame 52 may include the printer frame or some other fixed
structure within the all-in-one device 10 which is generally fixed
relative to other moving parts. Extending through the frame 52 is a
cam shaft 54. Operably connected to the cam shaft 54 is a cam 58
which either rotates with and/or rotates about the cam shaft 54.
The cam 58 is generally round in shape but may take various
geometric shapes which provides the function described further
herein. The cam 58 is rotatably connected to the cam shaft 54 so
that it rotates along a preselected eccentric profile or off center
manner so that the rotation of the cam 58 about the pivot point 56
provides motion for linkage 50 and the pressure roll 44.
Alternatively, some device may be substituted for the cam 58, such
as a solenoid or other such mover which functions with the variable
pressure roll linkage 50.
[0043] Adjacent the cam 58 is a first upper linkage 60 which
functions as a follower and remains engaged to the cam 58. The
first linkage 60 may comprise various shapes but is exemplarily
depicted as rectangular with a first end 66 and a second end 68.
The first linkage 60 is pivotally connected at a pivot point 62
either indirectly or directly to a fixed structure, such as the
frame 52. The cam 58 engages the linkage 60 at contact point 64 and
remains in contact during operation. As the cam 58 rotates, the
first linkage or follower 60 moves from a normal position (shown in
FIG. 3) wherein the pressure roll 44 is loaded to a second position
where the pressure roll 44 is generally unloaded. The cam 58 may be
rotated by various components including a motor and transmission
such as belt drive or gear drive. Alternatively, the cam 58 may be
driven by a gear drive and motor utilized for media advancing. It
should be understood by one skilled in the art that various motion
means may be used to cause movement and vary pressure on the
pressure roller 44.
[0044] At the second end of the first linkage 60 is a biasing or
elastic member 70 having a first end 72 and a second end 74. The
biasing member 70 is depicted as a coil spring but one of ordinary
skill in the art will recognize that various alternative biasing
devices may be utilized to connect the first linkage 60 and a
second linkage 80. The biasing member 70 is shown in its normal
extended or tensioned position between the first linkage 60 and the
second linkage 80. In the normal extended position, the pressure
roll 44 is biased toward the feed roll 42 and contacts the feed
roll 44 unless media M is moving there between. The cam 58 may
circular as shown and positioned on cam shaft 54 so that the
centerline of cam 58 is not coincident with the rotational
centerline of cam shaft 54 as shown in FIG. 3. Alternatively, cam
58 may be oval or elliptical in shape and be mounted so that its
centerline is coincident with the centerline of cam shaft 54.
Either form of cam provides a preselected eccentric profile or path
along which first linkage 60 travels as the cam 58 is rotated such
that the pressure provided by biasing member 70 transitions from a
predetermined maximum amount to a predetermined minimum amount.
This can be accomplished by rotating the cam in a single direction
or by reversing the direction of rotation of the cam. It should be
realized that if the cam rotation is reversible that the
configuration of the cam need not be circular or elliptical but may
be semi-circular or semi-elliptical. The particular form and method
of rotating the cam is left to the artisan.
[0045] The second linkage or pressure roll housing 80 is also
pivotally connected to the frame 52 at pivot point 82. The second
linkage 80 has a first end 84 and a second end 86 disposed on
either side of the pivot point 82. The first end 84 is connected to
the first linkage 60 by the biasing member 70. The second end of
the second linkage 86 has at least one pressure roll 44 and
according to one embodiment may have a plurality of pressure rolls
44 in contact with a feed roll 42. The contact between the feed
roll 42 and the pressure roll 44 defines a nip 46 wherein media M
is grasped for feeding to the printing zone beneath cartridge 28.
The pressure rolls 44 are rotatably connected to the pressure roll
housing 80 so as to rotate freely with the rotation of the feed
roll 42 or media M passing between the pressure and feed rollers
44, 42. With the pressure rolls 42 forcing the media M into contact
with the feed roll 42 as the feed roll turns, the media sheet M
moves with the rotation of the feed roll 42 toward the exit system
36. The cam 58 is shown in contact with contact point 64 of the
first linkage or follower 60. A mark "A" on the cam 58 is depicted
at the contact point 64 for purpose of reference.
[0046] The exit system 36 comprises a driven exit roller 38 and an
idler roller such as a star wheel 37. The star wheel design is used
to minimize ink degradation during media feeding and is known to
one skilled in the art. The drive or exit roller 37 directs media
to the exit tray 24 through a feed nip defined between the rollers
37,38.
[0047] Referring now to FIGS. 5-6, the cam 58 has been rotated 180
degrees and the mark "A" is moved from its position in FIGS. 3-4.
Accordingly, the follower 60 pivots about pivot 62 and follows the
eccentric cam 58. Because of the shape of the cam 58, the follower
60 is positioned closer to the pivot point 56 defined by the cam
shaft 54. The follower 60 pivots about pivot point 62 at a steeper
angle so that the lower end 68 of the follower 60 moves downwardly
and unloads the biasing member 70. By unloading the biasing member
70, the force directed through the biasing member and acting on the
second linkage 80 is decreased or substantially removed such that
the linkage 80 pivots about pivot point 82 and so that the second
end 86 of the linkage 80 moves upward. As a result, the pressure
roll 44 is no longer pressed as heavily against feed roll 42 and
can move away from the feed roll 42.
[0048] Referring to FIGS. 1-6, in operation the linkage or variable
force means 50 varies the force on the pressure or idler roller 44.
First, media M is positioned in the input tray 22 for feeding
through the feed path 21. The media M is advanced into the feed
path 21 through the use of various components (not shown), for
instance, an auto-compensating mechanism as known in the art. As
the media M advances from the input tray 22 through the feed path
21 and to the nip 46, the at least one pressure roll 44 is in
contact with the feed roll 42 forcing the media M to move toward
the print zone defined under the cartridge 28. After moving through
the print zone, the leading edge of media M is engaged by the exit
system 36 which continues pulling the media through the print zone.
As the media M continues to move through the feed nip 46 and
through the print zone, the trailing edge of the media approaches
the nip 46. Simultaneously, the cam 58 begins rotation from its
position shown in FIG. 3 to its position shown in FIG. 5. During
such rotation, the first linkage 60 pivots about its pivot point 62
toward the cam shaft 54 which in turn relieves tension on the
biasing member 70. The contact point 64 of the first linkage 60 has
moved toward the first end 66 of the first linkage 60 with the
rotation of the cam 58 as the tension in the biasing member 70 is
relieved, and the pressure roll 44 is moved upwardly from the feed
roll 42 and media M such that a space is defined therebetween. As a
result, when the trailing edge of media M passes through the nip
46, the media M is not urged toward the exit system 36 as with
prior art devices. This design comprising a first linkage 60 and a
spring connected second linkage 80 is advantageous because rotation
of the cam 58 provides a gradual movement of the second linkage 80
and roller 44. Such gradual movement inhibits printing defects as
opposed to a sudden linkage movement which can occur with the
direct engagement of a cam and the second linkage or pressure
roller housing 80. Thus, the present invention utilizes a variable
force on the pressure roll 44 rather than a continuous force so
that the media trailing edge is not urged forwardly along the feed
path toward the print cartridge 28 and exit system 36. Further, the
linkage system 50 allows for greater movement of the mover, such as
the cam 58, resulting in only slight movement of the pressure
roller 44.
[0049] Referring now to FIG. 7, an alternative embodiment of an
all-in-one device 110 is depicted comprising a scanner 12 and a
printer portion 120. The scanner portion 12 comprises an
auto-document feed (ADF) scanner 30 and a flat bed scanner,
generally depicted at 117. The ADF scanner 30 comprises an input
tray 118 and an output tray 119, the device further comprises a
scanner bed 117 and a lid 114 attached to the scanner bed 117. Upon
opening of the lid 114, a platen (not shown) is revealed where
documents, photos or drawings may be placed for flatbed scanning.
The ADF scanner 30 is preferable for use in scanning stacks of
documents and other such media sizes which are appropriately sized
for such automatic scanning. The printing portion 120 comprises an
input tray 122 and an exit or output tray 124 disposed above the
input tray and thereby defining a C-shaped printing path, as
opposed to the L-shaped path of the device shown in FIG. 1.
[0050] Referring now to FIG. 8, a side schematic view of an
exemplary C-path printing portion 120 is depicted which may be
utilized in the all-in-one device 110 shown in FIG. 7. The side
view of the printing portion 120 has some detail removed for
purpose of clarity. A plurality of media M is disposed on the input
tray 122 at a lower portion of the printing portion feed mechanism.
Generally, the media M is picked by a paper picking mechanism, such
as an auto-compensating mechanism 130 and directed upwardly into
the feed path 121. The feed path is substantially C-shaped and
directs the leading edge of the media to the variable pressure roll
linkage 150. The variable pressure roll linkage 150 extends from a
fixed structure 152, such as a frame, and comprises a cam 158 which
rotates about a cam shaft 154 to move a first linkage 160 that
pivots about pivot point 162 and causes variable loading of a
biasing member 170. By loading and unloading the biasing member 170
a second linkage 180 pivots at pivot point 182 causing application
of force at the pressure roll 144 against the feed roll 142. As
previously described, as the trailing edge of a media sheet
approaches the nip 146 defined between the pressure roll 144 and
the feed roll 142, the cam 158 is rotated about its pivot point 156
so as to untension the biasing member 170 and cause the pressure
roll 144 to move away from the feed roll 142. With the pressure
roll 144 not applying pressure to the media, the media jump which
causes printing degradations is removed. As previously noted, the
leading edge of the media is engaged by the exit system 136 before
the pressure roll 144 completely disengages the media M so that the
media is pulled through the print zone by the exit system 136.
Thus, when the pressure roll 144 disengages from the feed roll 142,
the media maintains its advancement through the printer feed path
121. This media disengagement point with the feed roll 142 can be
sensed, using a flag or other means as is known in the art for
position sensing, and the force on the pressure rolled can be
increased either to the maximum amount of pressure available or
some intermediate amount of pressure by rotating cam 158 prior to
the arrival of the next sheet of media at the feed roller 142.
Conversely, the pressure at nip 146 can be increased after arrival
of the next sheet of media at feed roller 142 is sensed.
[0051] Referring now to FIG. 9, a side schematic view of the ADF
scanner 30 is depicted which may be utilized in either all-in-one
device 10, 110 (FIGS. 1 and 7) or in a standalone capacity. The ADF
scanner 30 is depicted including various portions of the feedpath
221 as well. A pick system 233 is shown disposed above the input
tray 18 for moving an uppermost media sheet from a media stack into
the feedpath 221. The pick system 233 may comprise an
auto-compensating mechanism, as known in the art, or may comprise
alternate media picking components. Near the entrance portion of
the feedpath 221 is a delivery system 230 which receives media
moved by the pick or input system 233. The delivery system 230
comprises at least one delivery drive roller 232 and at least one
delivery idler roller 234. A motor and gear train or other
transmission (not shown) cause rotation of the delivery drive
roller 232 for feeding the media M along feedpath 221. The delivery
idler roller 234 includes at least one roller that rotates freely
on an idler shaft 237. The at least one delivery idler roller 234
is biased toward the at least one delivery drive roller 232 by a
biasing member (not shown), such as a leaf spring to form a nip 235
between the delivery drive roller 232 and the delivery idler roller
234. The delivery system 230 receives media M picked by the pick
system 233 and feeds the media M through the feedpath 221 to a feed
system 240.
[0052] The feed system 240 comprises a feed drive roller 242 and an
opposed feed pressure roller 244. A motor and gear train or other
transmission (not shown) cause rotation of the feed drive roller
242 for feeding the media M along feedpath 221. The feed pressure
roller 244 is biased toward the feed drive roller 242 defining a
nip 246 therebetween which receives media M from the delivery
system 230 and directs the media M across a scanning station 280.
The pressure roller 244 is biased toward the feed drive 242 by a
variable force pressure roll linkage 250, as previously described.
Accordingly, a rotatable cam 258 or motion device operably mounted
on cam shaft 254 causes movement of a pivotable follower or first
linkage 260 that pivots about pivot point 262 on frame 252 and
which is connected to the pressure roller 264 via a biasing member
270 and second pivotable linkage 280 that pivots about pivot point
282 on frame 252. As the biasing member 270 is tensioned the
pressure roller 244 engages the drive roller 242. When the biasing
member 70 is unbiased, the pressure roller 244 moves away from the
feed drive roller 242. Rotation of the cam 258 causes the increase
or decrease in the amount of pressure exerted by the pressure
roller 244 on the feed drive roller 242 at the nip 246.
[0053] Between the feed system 240 and the exit system 336 is a
scanbar 300 including a representative scanning image sensor 302
schematically depicted as a series of mirror and a sensing element.
As previously discussed, media M passing through the feedpath 221
is exposed to light in order to acquire image data of the image or
text on the media. The variable force pressure roll linkage 250 is
useful in the present embodiment because with a feed system having
a biased pressure roller at a constant pressure media M can jump as
the trailing edge of media M exits through the nip of such a feed
system.
[0054] In operation, the pick system 233 directs media M from the
media tray 18 into the feedpath 221. The media M reaches the
delivery system 230 and is further directed to the feed system 240
through the feedpath 221. The pressure roller linkage 250 is
disposed in the first position to cause engagement between pressure
roller 244 and the feed drive roller 242. As the feed drive roller
242 causes advancement of the media M toward the image sensor 300
and associated scan area, the trailing edge of the media M
approaches the feed system 240. Prior to the trailing edge of the
media M reaching nip 246 defined between the rollers 242, 244, the
linkage 250 is operated so as to vary pressure on the feed drive
roller 262 by the pressure roller 264. At this point the linkage
250 is operated so that the pressure in the nip 246 is
substantially reduced or is negligible. In other words, the moving
device causes actuation of the first and second linkages 260, 280
as well as the biasing member 270.
[0055] With the various embodiments described herein after the
trailing edge of the media M exits the nip, the variable pressure
linkages 50, 150, and 250 can be operated such that the pressure
exerted by the pressure rollers 44, 144 and 244 at nip is increased
until the desire feeding pressure is reached. This can occur prior
to the leading edge of the next sheet of media M reaching nip 46,
146, 246 or it may occur after the next sheet in already within the
nip. For example, it may be advantageous with thicker media to have
reduced pressure at nip possibly preventing damage to the edge of
the media or allowing a reduction in the amount of force need to
drive such media along the media feedpath.
[0056] The present invention allows for varying of force on a
pressure roller when a media trailing edge passes a feed nip
thereby inhibiting media jump and printing and scanning
degradation.
[0057] The foregoing description of several methods and an
embodiment of the invention has been presented for purposes of
illustration. It is not intended to be exhaustive or to limit the
invention to the precise steps and/or forms disclosed, and
obviously many modifications and variations are possible in light
of the above teaching. It is intended that the scope of the
invention be defined by the claims appended hereto.
* * * * *