U.S. patent application number 11/740293 was filed with the patent office on 2008-10-30 for sheet discharge roller assembly for an automatic document feeding apparatus.
Invention is credited to Wayne E. Foote, Jeffrey C. Madsen, Kyi Thu Maung, Thaddie Natalaray, Keng Leong NG, Toh Tung Wong.
Application Number | 20080265485 11/740293 |
Document ID | / |
Family ID | 39885987 |
Filed Date | 2008-10-30 |
United States Patent
Application |
20080265485 |
Kind Code |
A1 |
Wong; Toh Tung ; et
al. |
October 30, 2008 |
Sheet Discharge Roller Assembly For An Automatic Document Feeding
Apparatus
Abstract
A sheet discharge roller assembly for a sheet feeding apparatus
includes an upper cylindrical exit roller mounted on a rotatable
drive shaft and a lower cylindrical pinch roller having a wheel
attached to one end. The pinch roller has a length that is longer
than the length of the exit roller and is moveable into contact
with the exit roller so as to form a nip for gripping a print media
to be discharged. The wheel has a diameter that is larger than that
of the pinch roller and an outer circumferential edge composed of a
plurality of protruding contact portions arranged in a radial
pattern. The wheel is positioned so that the wheel can contact the
media sheet being gripped and cause the sheet to deform
temporarily, thereby making the sheet more rigid.
Inventors: |
Wong; Toh Tung; (Singapore,
SG) ; NG; Keng Leong; (Singapore, SG) ; Foote;
Wayne E.; (Eagle, ID) ; Madsen; Jeffrey C.;
(Eagle, ID) ; Natalaray; Thaddie; (Singapore,
SG) ; Maung; Kyi Thu; (Singapore, SG) |
Correspondence
Address: |
HEWLETT PACKARD COMPANY
P O BOX 272400, 3404 E. HARMONY ROAD, INTELLECTUAL PROPERTY ADMINISTRATION
FORT COLLINS
CO
80527-2400
US
|
Family ID: |
39885987 |
Appl. No.: |
11/740293 |
Filed: |
April 26, 2007 |
Current U.S.
Class: |
271/10.11 ;
271/314 |
Current CPC
Class: |
B65H 2801/06 20130101;
B65H 2404/133 20130101; B65H 2404/1431 20130101; B65H 2301/51214
20130101; B65H 29/70 20130101 |
Class at
Publication: |
271/10.11 ;
271/314 |
International
Class: |
B65H 29/20 20060101
B65H029/20; B65H 5/00 20060101 B65H005/00 |
Claims
1. A sheet discharge roller assembly comprising: an upper
cylindrical exit roller mounted on a rotatable drive shaft; and a
lower cylindrical pinch roller having a wheel attached to only one
end so as to rotate synchronously with said pinch roller, said
wheel having a diameter that is larger than that of the pinch
roller and an outer circumferential edge composed of a plurality of
protruding contact portions arranged in a radial pattern, wherein
said pinch roller has a length that is longer than the length of
the exit roller and is moveable into contact with said exit roller
so as to form a nip for gripping a print media to be discharged,
and said wheel is positioned so that said wheel can contact the
media sheet being gripped and cause the sheet to deform
temporarily, thereby making the sheet more rigid.
2. The sheet discharge roller assembly of claim 1, wherein the
outer circumferential edge of the wheel has a scalloped edge
configuration.
3. The sheet discharge roller assembly of claim 1, wherein the
outer circumferential edge of the wheel has a serrated edge
configuration.
4. The sheet discharge roller assembly of claim 1, wherein the
pinch roller is rotatably mounted to a housing, and is maintained
in a spring-biased position by a U-shaped wire spring such that the
pinch roller can be spring biased against the exit roller to define
a nip therebetween.
5. A sheet discharge roller assembly comprising: two upper
cylindrical exit rollers mounted on a rotatable drive shaft; and
two lower cylindrical pinch rollers opposing said exit rollers,
each pinch roller having a wheel attached to only one end so as to
rotate synchronously with said pinch roller, said wheel having a
diameter that is larger than that of the pinch roller and an outer
circumferential edge composed of a plurality of protruding contact
portions arranged in a radial pattern, wherein each pinch roller is
moveable into contact with a corresponding exit roller so as to
form a nip for gripping a print media to be discharged, each pinch
roller has a length that is greater than the length of the
corresponding exit roller, and the pinch rollers are arranged so
that the ends without the wheels are facing each other and the
distance between the wheels is greater than the combined lengths of
the exit rollers plus the distance between the exit rollers,
whereby the wheels can contact the media sheet being gripped near
the side edges of the sheet and cause the sheet to deform
temporarily, thereby making the sheet more rigid.
6. The sheet discharge roller assembly of claim 5, wherein the
outer circumferential edge of the wheel has a scalloped edge
configuration.
7. The sheet discharge roller assembly of claim 5, wherein the
outer circumferential edge of the wheel has a serrated edge
configuration.
8. The sheet discharge roller assembly of claim 5, wherein each
pinch roller is rotatably mounted to a housing, and is maintained
in a spring-biased position by a U-shaped wire spring such that the
pinch roller can be spring biased against the corresponding exit
roller to define a nip there between.
9. An automatic document feeder comprising: an input tray for
supporting a stack of media sheets; an output tray; a main media
path for guiding a media sheet from the input tray to a scanning
region and from the scanning region to the output tray; a pickup
unit for picking a sheet, one by one, from the stack of media
sheets in the input tray and feeding the sheet into the main media
path; and a sheet discharge roller assembly configured to discharge
the sheet onto the output tray, said sheet discharge roller
assembly comprising: (a) at least one upper cylindrical exit roller
mounted on a rotatable drive shaft; and (b) at least one lower
cylindrical pinch roller having a wheel attached to only one end so
as to rotate synchronously with said pinch roller, said wheel
having a diameter that is larger than that of the pinch roller and
an outer circumferential edge composed of a plurality of protruding
contact portions arranged in a radial pattern, wherein said pinch
roller has a length that is longer than the length of the exit
roller and is moveable into contact with said exit roller so as to
form a nip for gripping a print media to be discharged, and said
wheel is positioned so that said wheel can contact the media sheet
being gripped and cause the sheet to temporarily deform, thereby
making the sheet more rigid.
10. The automatic document feeder of claim 9, wherein there are two
spaced-apart upper cylindrical exit rollers mounted on the drive
shaft and there are two lower cylindrical pinch rollers in opposing
relationship to the exit rollers, each pinch roller being moveable
into contact with a corresponding exit roller so as to form a nip,
and wherein the pinch rollers are arranged so that the ends without
the wheels are facing each other, and the distance between the
wheels is greater than the combined lengths of the exit rollers
plus the distance between the exit rollers, whereby the wheels can
contact the media sheet being gripped near the side edges of the
sheet and cause the sheet to deform temporarily, thereby making the
sheet more rigid.
11. The automatic document feeder of claim 10, wherein each pinch
roller is rotatably mounted to a housing, and is maintained in a
spring-biased position by a U-shaped wire spring such that the
pinch roller can be spring biased against the corresponding exit
roller to define a nip there between.
Description
FIELD OF THE INVENTION
[0001] The present invention generally relates to sheet discharge
systems, particularly sheet discharge systems for automatic
document feeding apparatuses.
BACKGROUND
[0002] Many multifunction printers, copying machines and
stand-alone scanners are provided with an automatic document feeder
(ADF) for automatically transporting individual sheets from a stack
of media sheets to an image reading region, and then ejecting and
restacking the sheets automatically onto an output tray. It is
desirable to neatly restack the media sheets as the sheets exit the
ADF. However, this may be difficult to achieve. The incoming
ejected sheet tends to slide across the previously ejected sheet.
The friction between the sheets may lead to incomplete ejection or
skewing of the sheets relative to each other. Known solutions for
this problem include modifying the geometry of the output tray to
achieve proper stacking, such as inclining the output tray at a
steep angle or placing several edge guides on the output tray.
These known solutions either produce an unattractive output design
or add cost to the ADF. There remains a need for improving the
stacking of ejected sheets in ADF devices without adding special
features to the output tray or modifying the geometry of the output
tray.
SUMMARY
[0003] The present invention provides a sheet discharge roller
assembly that can improve stacking of media sheets at the output
area of an automatic document feeder without adding special
features to the output area. In one embodiment, the sheet discharge
roller assembly includes an upper cylindrical exit roller mounted
on a rotatable drive shaft and a lower cylindrical pinch roller
having a wheel attached to one end. The pinch roller has a length
that is longer than the length of the exit roller and is moveable
into contact with the exit roller so as to form a nip for gripping
a print media to be discharged. The wheel has a diameter that is
larger than that of the pinch roller and an outer circumferential
edge composed of a plurality of protruding contact portions
arranged in a radial pattern. The wheel is positioned so that the
wheel can contact the media sheet being gripped and cause the sheet
to deform temporarily, thereby making the sheet more rigid.
[0004] The objects and advantages of the present invention will
become apparent from the detailed description when read in
conjunction with the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a schematic cross-sectional view showing an
exemplary automatic document feeder which incorporates a sheet
discharge roller assembly according to an embodiment of the present
invention.
[0006] FIG. 2 is an isometric view showing the main components of
the sheet discharge roller assembly according to an embodiment of
the present invention
[0007] FIG. 3 is an isometric view showing a lower pinch roller,
which is part of the sheet discharge roller assembly shown in FIG.
2.
DETAILED DESCRIPTION
[0008] FIG. 1 shows an exemplary automatic document feeder (ADF) 10
which incorporates a sheet discharge roller assembly 16 according
to an embodiment of the present invention. The ADF 10 includes a
sheet supply tray 11 for holding a stack of media sheets
(hereinafter, simply referred to as "media stack"), a pickup unit
12, a set of de-skew rollers 13, a plurality of transport rollers
14 and 15, a sheet discharge roller assembly 16, and an output tray
17. The ADF 10 includes a substantially U-shaped, main media path
P1 for guiding the media sheet from the pickup unit 12 to the
output tray 17. An optical window W and an image reader R, e.g. an
optical scanner, are arranged along the media path P1 so that the
image data on one side of the media sheet can be read through the
optical window W by the image reader R. As such, the region above
the optical window W defines a scanning region of the ADF 10. The
pickup unit 12 includes a pick roller 12a operable to pull (i.e.,
"pick") the uppermost sheet from the media stack and a feed roller
12b operable to advance the uppermost sheet toward the de-skew
rollers 13. The de-skew rollers 13 are operable to perform skew
correaction of the media sheet and to advance the same sheet along
the main media path P1 toward the transport rollers 14. The
transport rollers 14 are designed to advance the media sheet
further downstream toward the scanning region where the optical
window W is located. The transport rollers 15 are configured to
advance the media sheet from the image reading position toward the
sheet discharge roller assembly 16. The sheet discharge roller
assembly 16 is configured to discharge the scanned media sheet to
the output tray 17. The ADF 10 also includes a switch-back path P2
that extends from the sheet discharge roller assembly 16 to the
de-skew rollers 13 so that the media sheet may be re-introduced
into the main media path P1 for scanning on the opposite side. The
ADF 10 is operable in a simplex mode, in which one side of a
document is scanned, or a duplex mode, in which both sides of a
document are scanned.
[0009] Referring to FIG. 2, the sheet discharge roller assembly 16
includes two pairs of rollers (21, 22) arranged along the width of
the media path, each pair including an upper cylindrical exit
roller 21 cooperating with a lower cylindrical pinch roller 22. The
exit rollers 21 are fixedly mounted to a drive shaft 23, which is
operatively connected to a media motor (not shown) such that the
exit rollers 21 can be driven to rotate by a drive force from the
media motor. The pinch rollers 22 are rotatably mounted to a
housing 24 and are moveable relative to the exit rollers 21. One
end of the pinch roller 22 is attached to a wheel 22a with
scalloped circumferential edge. The pinch rollers 22 are arranged
so that the ends without the wheels are facing one another, and the
distance between the wheels 22a is greater than the combined
lengths of the two exit rollers 21 plus the distance between the
two exit rollers 21. As shown in FIG. 2, the scalloped
circumferential edge of wheel 22a has a plurality of protruding
contacting portions alternating with a series of small curves,
which define the non-contacting portions. Although a scalloped edge
design is shown, it should be understood that other circumferential
edge designs are possible as long as there are a plurality of
protruding contacting portions arranged in a radial pattern at a
predetermined pitch. For example, the circumferential edge of wheel
22a may take the form of a serrated edge, i.e. an edge with a
plurality of tips like the edge of a saw. The wheel 22a has a
diameter that is larger than the diameter of the pinch roller 22.
The length of the pinch roller 22 is longer than that of the exit
roller 21. The pinch rollers 22 are spaced so that the wheels 22a
can contact the media sheet near the side edges thereof.
[0010] FIG. 3 shows an unobstructed view of one of the lower pinch
rollers 22 rotatably mounted to housing 24. The housing 24 is
movable relative to the exit rollers 21 to cause the pinch rollers
22 to be in nipping contact with or out of contact with the exit
rollers 21. As shown in FIG. 3, the housing 24 has slots 24s for
receiving the axles 22b of each pinch roller 22. A substantially
U-shaped, wire spring 25 is mounted to the housing 24 so as to be
pivotable about axis X with the free ends of the spring in contact
with and under the axles 22b of the pinch roller 22 as shown in
FIG. 3. By this arrangement, the pinch roller 22 may be spring
biased upward against the exit roller 21 via wire spring 25 to form
a nip for nipping the media sheet. The wire spring provides the
required nipping force while allowing the axles 22b of the pinch
roller 22 to be moveable within the slots 24s in a direction
substantially orthogonal to the axis of the axles 22 so as to
accommodate various media thicknesses.
[0011] During the process of discharging a media sheet to the
output tray, the pinch rollers 22 are biased against the
corresponding exit rollers 21 so as to define a nip that grips the
media sheet being discharged, and the pinch rollers 22 rotate in
synchronism with the rotation of the exit rollers 21 to move the
media sheet toward the output tray. The wheels 22a attached to
pinch rollers 22 cause the nipped media sheet to be deformed
temporarily, thereby making the sheet more rigid. This deformation
results in less droop and drag of the media sheet as the sheet
exits the ADF, thereby resulting in a more orderly media stacking.
Furthermore, the scalloped edge design gently pushes the trailing
edge of the exiting media sheet past the exit rollers 21, thereby
preventing incomplete ejection and clinging of the media sheet at
the output area of the ADF.
[0012] While particular embodiments of the present invention have
been described, it will be understood by those skilled in the art
that modifications and substitutions can be made without departing
from the scope of the invention as set forth in the following
claims.
* * * * *