U.S. patent application number 11/320431 was filed with the patent office on 2007-07-05 for image forming systems with gimbaled retard feeder device.
This patent application is currently assigned to XEROX CORPORATION. Invention is credited to Henry T. JR. Bober, Alan E. Francis, Linn C. Hoover.
Application Number | 20070152397 11/320431 |
Document ID | / |
Family ID | 38223553 |
Filed Date | 2007-07-05 |
United States Patent
Application |
20070152397 |
Kind Code |
A1 |
Bober; Henry T. JR. ; et
al. |
July 5, 2007 |
Image forming systems with gimbaled retard feeder device
Abstract
An image forming system may include a photoreceptor, a sheet
feeding apparatus and a retard feeder device that includes a feed
roll, retard roll and nudger roll. The retard feeder device
transfers a sheet of paper from the sheet feeding apparatus,
through the sheet imaging media registration system and on to the
photoreceptor. The retard roll is mounted in a loading bracket to
allow the Retard Rollers to be loaded against the Feeder Rollers.
The loading bracket is mounted on a pivot pin so that the retard
rollers can pivot to maintain equal pressure against both feed
roll. A retard feeder device may include a bracket, a feed roll
assembly that includes two tires, a retard roll assembly that
includes two tires and a nudger roll assembly. The retard roll
loading bracket is fastened to a pivot pin so that the retard
rollers can pivot to maintain an equal pressure between the tires
of the retard roll assembly and the tires of the feed roll
assembly.
Inventors: |
Bober; Henry T. JR.;
(Fairport, NY) ; Hoover; Linn C.; (Webster,
NY) ; Francis; Alan E.; (Fairport, NY) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC.
P.O. BOX 19928
ALEXANDRIA
VA
22320
US
|
Assignee: |
XEROX CORPORATION
Stamford
CT
|
Family ID: |
38223553 |
Appl. No.: |
11/320431 |
Filed: |
December 29, 2005 |
Current U.S.
Class: |
271/124 |
Current CPC
Class: |
B65H 3/5261 20130101;
G03G 15/6567 20130101 |
Class at
Publication: |
271/124 |
International
Class: |
B65H 3/52 20060101
B65H003/52 |
Claims
1. An image forming system, comprising: a photoreceptor; a sheet
feeding apparatus; and a retard feeder device that includes a feed
roll assembly, a retard roll assembly and a nudger roll assembly,
the retard roll assembly including a retard roll tire nip, the feed
roll assembly including a feed roll tire nip, the retard feeder
device transferring a sheet of paper from the sheet feeding
apparatus to a registration-deskew station and on to the
photoreceptor; and the retard roll assembly mounted on a gimbal
pivot pin so that the retard roll assembly pivots into alignment
with the feed roll assembly to maintain equal pressure between both
of the feed and retard roll tire nips.
2. The image forming system of claim 1, wherein the retard roll
assembly pivots either in a clockwise or counter-clockwise
direction around the gimbal pivot pin.
3. The image forming system of claim 1, wherein the gimbal pivot
pin is positioned in between a feed head frame and the retard
feeder device.
4. The image forming system of claim 3, the retard roll assembly
comprising a carrier bracket, wherein a gimbal bracket is connected
to the carrier bracket and is fastened to the pivot pin using a
fastener.
5. The image forming system of claim 4, comprising a drag clutch
attached to the carrier bracket of the retard roll assembly.
6. The image forming system of claim 5, wherein the drag clutch
allows the retard roll assembly to overcome a frictional drag
torque of the retard roll assembly and rotate when a sufficient
friction force is place on the retard roll assembly.
7. The image forming system of claim 5, comprising a balance weight
connected to the carrier bracket of the retard roll assembly, the
balance weight offsetting an asymmetric moment from the drag clutch
and forcing a center of gravity back to an axis of the gimbal pivot
pin.
8. The image forming system of claim 7, wherein the feed roll
assembly and retard roll assembly are formed as feed roll and
retard roll tires, respectively, and the retard roll assembly
having the carrier bracket is spring loaded so that the retard roll
assembly develops equal pressure on the feed and retard roll
tires.
9. The image forming system of claim 7, wherein the feed roll
assembly and retard roll assembly are formed as tires composed of
urethane, silicon or a high coefficient friction material.
10. The image forming system of claim 9, wherein the nudger roll
assembly contacts the sheet of paper and rotates to advance the
sheet of paper to the feed roll assembly and retard roll assembly
from the sheet feeding apparatus.
11. A retard feeder device, comprising: a feed head frame; a feed
roll assembly that includes either two tires or one wide roller; a
retard roll assembly that includes a carrier bracket, a gimbal
bracket, and either two tires or one wide roller; and a nudger roll
assembly, the retard roll assembly fastened to a gimbal pivot pin
so that the retard roll assembly pivots to maintain an equal
pressure between the tires or roller of the retard roll assembly
and the tires or roll of the feed roll assembly.
12. The retard feeder device of claim 11, wherein the retard roll
assembly including the carrier bracket and the gimbal bracket is
fastened to the pivot pin using a fastener.
13. The retard feeder device of claim 12, wherein the retard roll
assembly pivots either in a clockwise or counter-clockwise
direction around the gimbal pivot pin.
14. The retard feeder device of claim 13, wherein the retard roll
assembly having the carrier bracket is connected to gimbal pivot
pin using the gimbal bracket.
15. The retard feeder device of claim 11, comprising a drag clutch
connected to the carrier bracket.
16. The retard feeder device of claim 15, wherein the drag clutch
allows the retard roll assembly to overcome frictional drag torque
and rotate when a sufficient frictional force is place on the
retard roll assembly.
17. The retard feeder device of claim 16, comprising a balance
weight connected to the carrier bracket, the balance weight
offsetting an asymmetric moment from the drag clutch and forcing a
center of gravity back to an axis of the gimbal pivot pin.
18. The retard feeder device of claim 17, the feed roll assembly
comprising tires, wherein the retard roll assembly is spring loaded
so that the retard roll assembly develops equal pressure against
the feed roll assembly tires.
19. The retard feeder device of claim 18, wherein the tires are
composed of urethane, silicon or a high coefficient friction
material.
20. The retard feeder device of claim 19, the retard roll assembly
including a retard roll nip, the feed roll assembly including a
feed roll nip, wherein the nudger roll assembly contact a sheet of
paper and rotates to advance the sheet of paper to the feed roll
and retard roll nips from a stack of paper.
Description
BACKGROUND
[0001] The disclosure relates to image forming systems, and more
particularly to a retard feeder device that may be used in the
image forming systems.
[0002] Retard feeders may be used in image forming systems to
advance or separate an image receiving medium, such as a substrate
or sheet of paper, from a storage device or tray that holds the
image receiving medium. The retard feeder may include individual
rolls. For example, the retard feeder may include a feed roll
assembly, retard roll assembly and a nudger roll assembly. The feed
roll assembly is positioned opposite the retard roll assembly, and
each roll assembly often may include either two rollers or tires or
a single wide roller. The feed and retard roll assemblies contact
each other forcibly to create a nip. The nudger roll assembly is
forcibly positioned on top of a stack of paper and frictionally
nudges the top sheet [or sheets] into the Feeder-Retard Roller Nip.
The feed roll assembly is driven so that they advance the sheet of
paper out of the media supply tray. The retard roll is not driven
in a semi-active retard feeder, but the retard roll may include a
drag clutch. Maintaining an equal load between the two Feeder and
Retard Tires is essential to maintaining reliable feeding operation
and minimizing media skew or rotation.
[0003] The drag clutch establishes a well controlled frictional
drag torque on the retard roll assembly. It permits the retard
roller assembly to rotate when enough frictional drive force is
place on the retard roll by a sheet of paper or other like imaging
media being driven through the Feeder-Retard Roller Nip. This is
the case when a single sheet of imaging media has entered the
Feeder-Retard Nip. The single sheet is fed with the feeder roll
assembly while the retard roll assembly is rotated by the passing
of the single sheet. If not enough friction is placed on the retard
roll, the retard roll does not rotate and it will frictionally hold
back or `retard` the sheet. This is the case when two or more
sheets of imaging material enter the Feeder-Retard Nip. Thus, the
drag clutch may operate as a drag brake. For a single sheet of
paper to through the Feeder-Retard Nip, the Feed Roller Drive Force
on the sheet must be capable of overcoming the Retard Drag Torque.
However, if two sheets of paper, e.g., a multi-feed, are advanced
from the paper tray through the Feeder-Retard Nip, the Retard Drag
Torque will hold back or retard the bottom sheet(s) as long as the
Drag Force on the Retard Roll is greater than the sheet to sheet
friction.
SUMMARY
[0004] The feed roll assembly, retard roll assembly and the nudger
roll assembly of the retard feeder device are generally positioned
parallel to each other but the feed and retard roller assemblies
need to be precisely parallel to each other because they are loaded
against one another to create the nip. The parallel alignment of
the feed roll assembly and retard roll assembly is extremely
important because equal pressure must exist between both pairs of
feed and retard roller tires or both sides of a single wide roll
nip so that paper is fed into a image forming system from a storage
device with very limited skew. Minimizing skew is important so as
to not over stress the Registration & Deskew System, located in
the Image Forming System.
[0005] In order to acceptably align the feed roll assembly axis and
retard roll assembly axis to each other, and create the equal
pressure in both feed/retard roll nips, the composition or
Durometer of conventional rollers or tires may be altered or
reduced to allow the tire deformation to adjust for a lack of
parallel alignment and produce an appropriately balanced nip
pressure across both feeder/retard tire nips. However, when the
tires are formed of harder or higher Durometer to provide better
wear resistance and roller life, the alignment of the feed and
retard roll assemblies becomes more sensitive and unequal pressure
may still exist between the feed and retard roll tire nips.
Moreover, some materials used for the tires are expensive and
difficult to manufacture accurately enough to produce the necessary
parallelism. If a uniform pressure, or nip force, does not exist
between both feed roller and the retard roller assemblies, a non
uniform drive force will be produced by the two feeder/retard tire
nips. This imbalanced drive force can cause print media skewing or
rotation. The low drive force can also allow the retard roller
assembly to slip or even stall, causing the leading edge of a sheet
entering the feeder/retard tire nip to stub on the stalled retard
roll and misfeed. A paper jam results from the misfeed because when
the leading edge of the print media or paper stubs on the stalled
retard roller tires, it rolls over or folds under and does not
enter the feeder/retard tire nip.
[0006] Thus, in accordance with various exemplary embodiments, a
retard feeder device may be connected to a gimbal, e.g., a pivot
pin, to allow the retard roll assembly to pivot into parallel
alignment with the feeder roll assembly and create uniform pressure
between the two sets of tires. Using the gimbal allows longer life
higher Durometer materials and/or less expensive manufacturing
processes to be used for the tires because the gimbal ensures
proper alignment and equal pressure between the feed and retard
roll assemblies.
[0007] In various exemplary embodiments of the disclosure, an image
forming system may include a photoreceptor, a Registration-Deskew
station and a sheet feeding apparatus such as a retard feeder
device. Such a retard feeder device will include a feed roll
assembly, a retard roll assembly and a nudger roll assembly. The
retard feeder device transfers a sheet of paper from the sheet
feeding apparatus storage tray to the Registration-Deskew Station
and then to photoreceptor for imaging. The retard roll is mounted
to a retard roller assembly loading bracket and forcibly positioned
against the feed roller assembly.
[0008] A retard feeder device may include a bracket, a feed roll
assembly that includes either two widely spaced tires or a single
wide tire, a retard roll assembly that includes either two widely
spaced tires or a single wide tire and a nudger roll assembly. The
retard roll loading bracket is fastened to a gimbal or pivot pin so
that the retard roll assembly pivots into parallel alignment with
the feeder roll assembly to maintain an equal pressure between the
tires of the retard roll assembly and the tires of the feed roll
assembly.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Various exemplary embodiments of the systems and methods
according to the invention will be described in detail, with
reference to the following figures, wherein:
[0010] FIG. 1 shows an exemplary diagram of an image forming system
that includes a retard feeder device;
[0011] FIG. 2 shows an exemplary diagram of the retard feeder
device positioned on a feed head frame;
[0012] FIG. 3 shows an exemplary detailed diagram of the retard
feeder device; and
[0013] FIG. 4 shows an exemplary system without a gimbaled retard
pivot.
DETAILED DESCRIPTION OF EMBODIMENTS
[0014] FIG. 1 shows an exemplary diagram of an image forming system
100 that includes a retard feeder device. The system includes a
belt 10 having a photoconductive surface 12 deposited on a
conductive ground layer 14. The photoconductive surface 12 may be
made from a photo responsive material, for example, one including a
charge generation layer and a transport layer. The conductive layer
14 may be made from a thin metal layer or metallized polymer film
that is electrically grounded. The belt 10 moves in the direction
of arrow 16 to advance successive portions of photoconductive
surface 12 sequentially through the various processing stations
disposed about the path of movement thereof. The belt 10 may be
entrained about a stripping roller 18, tensioning roller 20 and
drive roller 22. The drive roller 22 may be mounted rotatably in
engagement with belt 10. A motor 24 rotates roller 22 to advance
belt 10 in the direction of arrow 16. The roller 22 may be coupled
to a motor 24 by suitable means, such as gears and/or a drive belt.
The belt 10 may be maintained in tension by a pair of springs (not
shown) resiliently urging the tensioning roller 20 against the belt
10 with the desired spring force. The stripping roller 18 and
tensioning roller 20 may be mounted to rotate freely.
[0015] A portion of the belt 10 may pass through a charging station
A. At the charging station A, a corona generating device 26 may
charge the photoconductive surface 12 to a relatively high,
substantially uniform potential. After the photoconductive surface
12 of the belt 10 is charged, the charged portion may be advanced
through an exposure station B.
[0016] At the exposure station B, a controller or electronic
subsystem (ESS) 28 may receive the image signals representing the
desired output image and process the signals to convert them to a
continuous tone or gray scale rendition of the image that is
transmitted to a modulated output generator, for example, the
raster output scanner (ROS) 30. The controller 28 may be a
self-contained, dedicated minicomputer. The image signals
transmitted to the controller 28 may originate from a computer,
thereby enabling the image forming system 100 to serve as a
remotely located printer for one or more computers. The image
forming system 100 may serve as a dedicated printer for a
high-speed computer. The signals from the controller 28,
corresponding to the continuous tone image desired to be reproduced
by the printing machine, may be transmitted to the ROS 30.
[0017] After the electrostatic latent image has been recorded on
the photoconductive surface 12, the belt 10 advances the latent
image to a development station C where the toner, in the form of
liquid or dry particles, is electrostatically attracted to the
latent image using commonly known techniques. At the development
station C, a magnetic brush development system 38 may advance
charged developer material into contact with the latent image. A
magnetic brush development system 38 may include two magnetic brush
developer rollers such as 40 and 42. The rollers 40 and 42 may
advance charged developer material into contact with the latent
image. The developer rollers may form a brush of carrier granules
and toner particles extending radially outward. The latent image on
Belt 10 attracts toner particles from the carrier granules forming
a toner powder image thereon. As successive electrostatic latent
images are developed, toner particles are depleted from the
developer material. A toner particle dispenser 44 dispenses toner
particles into a developer housing 46 of the development system
38.
[0018] As shown in FIG. 1, after the electrostatic latent image is
developed, the toner powder image present on the belt 10 advances
to the transfer station D. A print sheet 48 is advanced to the
transfer station D by a sheet feeding apparatus 50. The sheet
feeding apparatus 50 may include a retard feeder device 80 that
includes a feed roller assembly 81, retard roll assembly 82 and
nudger roller assembly 83. The nudger roll 83 may contact the
uppermost sheet of paper in the stack 54 and the roller assembly
rotates to advance the uppermost sheet of paper from the stack 54
to the feed roll assembly 81 and retard roll assembly 82. The feed
roller assembly 81 and retard roller assembly 82 may separate any
double fed sheets before forwarding the sheet into the
Registration-Deskew Station 205. The Registration-Deskew Station
may incorporate a set of clutched stalled Nip Rollers 210 and a
Buckle Chamber 215. After being deskewed, the fed sheet is driven
into a chute 56. The chute 56 may direct the advancing sheet of
support material into contact with photoconductive surface 12 of
belt 10 in a timed sequence so that the toner powder image formed
thereon contacts the advancing sheet at the transfer station D. The
transfer station D may include a corona generating device 58 that
sprays ions onto the back side of sheet 48 in order to attract the
toner powder image from photoconductive surface 12 to sheet 48.
After transfer, the sheet 48 continues to move in the direction of
arrow 60 onto a paper transport or conveyor (not shown) which
advances the sheet 48 to a fusing station E.
[0019] The fusing station E may include a fuser assembly 62 that
permanently affixes the transferred powder image to the sheet 48.
The fuser assembly 60 may include a heated fuser roller 64 and a
back-up or pressure roller 66. The sheet 48 passes between the
fuser roller 64 and back-up roller 66 with the toner powder image
contacting the fuser roller 64. In this manner, the toner powder
image is permanently affixed to the sheet 48. After fusing, the
sheet 48 advances through the chute 68 to output tray 72 for
subsequent removal from the printing machine by the operator.
[0020] After the print sheet is separated from photoconductive
surface 12 of belt 10, the residual toner/developer and paper fiber
particles adhering to photoconductive surface 12 are removed there
from at the cleaning station F. The cleaning station F may include
a rotatably mounted fibrous brush in contact with the
photoconductive surface 12 to disturb and remove paper fibers and a
cleaning blade to remove the nontransferred toner particles.
Subsequent to cleaning, a discharge lamp (not shown) floods the
photoconductive surface 12 with light to dissipate any residual
electrostatic charge from the image remaining thereon prior to the
charging thereof for the next successive imaging cycle.
[0021] FIG. 2 shows an exemplary diagram of the retard feeder
device 80 positioned on a feed head frame 90. As shown in FIG. 2, a
gimbal pivot pin 91 is positioned on the feed head frame wall 92 in
between the feed head frame wall 92 and the retard feeder device
80. A traditional feed head frame 90 could include retard assembly
carrier pivot ears on the feed head frame wall 92. They may be
altered or removed so that the gimbaled bracket 94, the retard
carrier bracket 95 and the retard roller assembly, 82 from FIG. 1,
is allowed to pivot on the pivot pin 91. By using the gimbal pivot
pin 91, the Gimbal Bracket 94 and the retard roll assembly 82 is
allowed to pivot. The pivoting motion of the retard roll assembly
82 allows the retard roller assembly to be parallel to the feeder
roller assembly. This ensures equal pressure between the tires of
the feed roller assembly 81 and the tires of the retard roller
assembly 82, which reduces sheet skew and misfeeds as the
individual sheets of paper are fed into an image forming system 100
from the stack 54.
[0022] In accordance with various exemplary embodiments, the gimbal
pivot pin 91 may be positioned on the feed head frame wall 92 as
shown in FIG. 2. The pivot pin 91 may be fastened to the feed hard
frame wall by any known fastening means, and the retard carrier
bracket 95 of the retard roll assembly 82 located within the retard
feeder device 80 may be axially retained on the pivot pin 91 using
a pin thrust fastener 93. The gimbal bracket 94 may be formed of,
for example, aluminum or plastic. The retard roll assembly 82 is
mounted in the retard carrier bracket 95 which is pivotally secured
to the gimbal bracket 94. The carrier pivot axis 96 is
perpendicular to the gimbal pin axis 91. The retard carrier bracket
95 and the retard roller assembly 82 are spring loaded to develop
the required nip force between the feeder and retard roller
assemblies, so that it develops equal pressure on both of the
retard roller assembly tires. Because the pivot pin 91 is fastened
to the feed head frame wall 92 perpendicular to the rotational axis
of the feed and retard roller assemblies 81 & 82, the pivot pin
91 allows the retard roll assembly 82 to rotate in a direction
shown by arrows A in FIG. 3 to correct or eliminate any gap between
feed roller assembly tires 81 a and retard roller assembly tires
82a. The gimbal pivot pin 91 must be positioned on the feed head
frame wall 92 symmetrically to and vertically above the combined
Center of Gravity 97 of the gimbaled parts [the gimbal bracket 94,
retard carrier bracket 95 and the retard roll assembly 82] to
ensure stability and to provide the necessary uniform pressure
between the individual feed and retard tires [81a/82a,
81b/82b].
[0023] For example, the gimbal pivot pin 91 must be positioned
central between the two feed rolls 81 a-b so that its longitudinal
axis points toward the paper stack 54 and be parallel to the plane
of the paper sheets. If the gimbal pivot pin axis is not
equidistant between the individual tire nips, the nip loads will
not be equal. The gimbal pivot pin 91 allows the gimbal bracket 94,
the retard carrier bracket 95 and the retard roll assembly 82 to
align with the feed roll assembly 81 and apply equal nip force to
both sets of tires. If the retard roll assembly 82 is not nominally
balanced, the off center weight may load one roller more than
another. Thus, a balance weight 87, e.g., a counterweight, may be
included as shown in FIG. 3 to offset an asymmetric moment from the
drag clutch 84. The balance weight 87 also forces the center of
gravity back to the pivot pin 91 axis. The drag clutch 84 is
attached to the retard carrier bracket 95. The drag clutch is
rotationally coupled to the retard roll assembly 82 using gears
86a-b. The balance weight 87 may be attached to the retard carrier
bracket 95.
[0024] FIG. 3 shows an exemplary detailed diagram of the retard
feeder device. The retard feeder device 80 self-aligns or pivots to
contact both feed roller tires with both retard roller tires with a
uniform pressure. As shown in FIG. 3, the retard feeder device 80
may include the feed roll assembly 81, retard roll assembly 82 and
nudger roll assembly 83. The feed roll assembly 81 may include feed
roller tires 81a-b, and it may be positioned above the retard roll
assembly 82. The retard roll assembly 82 may include retard roller
tires 82a-b. The feed roller tires 81a-b and retard roller tires
82a-b may be formed to resemble tires and they may be composed of
urethane, silicon or other suitable high coefficient of friction
materials. The drag clutch 84 limits the retard roll assembly 82
the media retarding frictional drag torque and rotate when enough
friction force is placed on the retard roll assembly 82. If not
enough friction force is placed on the surface of the retard roll
assembly 82, the retard roll assembly 82 does not rotate. Thus, the
drag clutch 84 may operate as a drag brake. The feed roll assembly
81 may be driven by a motor (not shown) and suitable gears or belts
(not shown). As power is applied to the motor, the motor drives or
rotates the feed roll assembly.
[0025] As shown in FIG. 4, without the gimbaled retard pivot
feature, the retard roller assembly 82 is uniformly contacting the
feed roll assembly 81, possibly indicating a high spot on one of
the tires, preventing uniform contact on both nips. However, a gap
88 exists between the feed roller tire 81b and retard roller tire
82b because the eccentric tire 81a pushes down on the retard roller
assembly 82 and the retard carrier bracket 95. The gap 88 indicates
a loss of nip pressure between the feed roller tire 81b and retard
roller tire 82b caused by the feed roll assembly 81 and retard roll
assembly 82 centerlines being rigidly fixed and unable to
accommodate high tire spots, tire eccentricities or tire diameter
differences. In other words, the feed roll 81centerline to the
retard roll 82 centerline side to side spacing remains fixed. The
eccentric tire contact on one side temporarily increases the nip
center distance on both sides, decreasing or totally eliminating
contact on the other tire nip. This creates an unbalanced nip force
between the two feed-retard nips.
[0026] With the gimbaled retard pivot, the retard roll assembly 82
self-aligns or pivots to contact both feed roller tires with both
retard roller tires with uniform pressure,. The uniformity of the
nip pressure is improved and the gap shown in FIG. 4 is eliminated.
Thus, sheet skewing and paper jams that occur in conventional
devices are significantly reduced or eliminated by providing a
uniform pressure across both feed-retard tire nips.
[0027] It will be appreciated that various of the above-disclosed
and other features and functions, or alternatives thereof, may be
desirably combined into many other different systems or
applications. Also, various presently unforeseen or unanticipated
alternatives, modifications, variations or improvements therein may
be subsequently made by those skilled in the art which are also
intended to be encompassed by the following claims.
* * * * *