U.S. patent application number 15/814018 was filed with the patent office on 2018-05-24 for sheet stacking device and image forming apparatus including the same.
This patent application is currently assigned to KYOCERA Document Solutions Inc.. The applicant listed for this patent is KYOCERA Document Solutions Inc.. Invention is credited to Terumitsu NOSO, Rina OKADA, Yasunori UENO.
Application Number | 20180141774 15/814018 |
Document ID | / |
Family ID | 62144777 |
Filed Date | 2018-05-24 |
United States Patent
Application |
20180141774 |
Kind Code |
A1 |
OKADA; Rina ; et
al. |
May 24, 2018 |
SHEET STACKING DEVICE AND IMAGE FORMING APPARATUS INCLUDING THE
SAME
Abstract
A sheet stacking device includes a sheet stacking section, pairs
of ejection rollers, an airflow generator, and an airflow guide.
The airflow guide has a center exhaust port and paired side exhaust
ports. An airflow is blown out from the center exhaust port toward
a central part of the lower surface of the sheet in a sheet width
direction perpendicular to a conveyance direction of the sheet.
Airflows are blown out from the respective paired side exhaust
ports toward respective sides of the lower surface of the sheet. An
amount of the airflow blown out from the center exhaust port is
larger than those of the airflows blown out from the respective
paired side exhaust ports.
Inventors: |
OKADA; Rina; (Osaka-shi,
JP) ; NOSO; Terumitsu; (Osaka-shi, JP) ; UENO;
Yasunori; (Osaka-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KYOCERA Document Solutions Inc. |
Osaka |
|
JP |
|
|
Assignee: |
KYOCERA Document Solutions
Inc.
Osaka
JP
|
Family ID: |
62144777 |
Appl. No.: |
15/814018 |
Filed: |
November 15, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B65H 2801/27 20130101;
B65H 29/246 20130101; B65H 31/10 20130101; B65H 2406/42 20130101;
B65H 29/125 20130101; B65H 2801/06 20130101; B65H 2301/4461
20130101; B65H 29/70 20130101; B65H 29/14 20130101; B65H 2301/51214
20130101 |
International
Class: |
B65H 29/12 20060101
B65H029/12; B65H 29/14 20060101 B65H029/14; B65H 29/24 20060101
B65H029/24 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2016 |
JP |
2016-225060 |
Claims
1. A sheet stacking device comprising: a sheet stacking section on
which a sheet is stacked; pairs of ejection rollers that eject the
sheet toward the sheet stacking section; an airflow generator
configured to generate airflows; and an airflow guide configured to
guide the airflows toward a lower surface of the sheet ejected from
the pairs of ejection rollers toward the sheet stacking section,
wherein the airflow guide has: a center exhaust port that is
located below the pairs of ejection rollers and from which an
airflow generated by the airflow generating section is blown out
toward a central part of the lower surface of the sheet in a sheet
width direction perpendicular to a conveyance direction of the
sheet; and paired side exhaust ports that are located on respective
opposite sides of the center exhaust port in the sheet width
direction and from which airflows generated by the airflow
generator are blown out toward respective sides of the lower
surface, and an amount of the airflow blown out from the center
exhaust port is larger than those of the airflows blown out from
the respective paired side exhaust ports.
2. The sheet stacking device according to claim 1, wherein the
center exhaust port and the paired side exhaust ports are directed
such that a first blowing angle made by the conveyance direction
and a blowing direction of the airflow blown out from the center
exhaust port is larger than a second blowing angle made by the
conveyance direction and a blowing direction of the airflow blown
out from each of the paired side exhaust ports.
3. The sheet stacking device according to claim 2, wherein the
sheet stacking section has an inclined surface ascending downstream
in the conveyance direction, and the paired side exhaust ports are
directed such that the second blowing angle is larger than a third
blowing angle made by the conveyance direction and the inclined
surface of the sheet stacking section.
4. The sheet stacking device according to claim 1, wherein the
airflow generator starts blowing the airflows before a leading edge
of the sheet passes through the pairs of ejection rollers and stops
blowing the airflows before the trailing edge of the sheet passes
through the pairs of ejection rollers.
5. The sheet stacking device according to claim 1, wherein the
airflow generator includes a first airflow generator and a second
airflow generator, the airflow guide includes a first duct and a
second duct, the first duct divides an airflow generated by the
first airflow generator and guides respective divided airflows to
the center exhaust port and one of the paired side exhaust ports,
and the second duct divides an airflow generated by the second
airflow generator and guides respective divided airflows to the
center exhaust port and the other of the paired side exhaust
ports.
6. The sheet stacking device according to claim 1, wherein the
pairs of ejection rollers includes: a plurality of lower ejection
rollers spaced from one another in the sheet width direction; and a
plurality of upper ejection rollers each disposed opposite to a
corresponding one of the lower ejection rollers, the lower ejection
rollers include: paired inside rollers disposed in a central part
of the sheet stacking device in the sheet width direction and
spaced from each other; and paired outside rollers disposed
adjacently outside of the respective inside rollers in the sheet
width direction, the center exhaust port is located blow a region
where the paired inside rollers are located, and the paired side
exhaust ports are located below the respective paired outside
rollers.
7. The sheet stacking device according to claim 6, wherein the
paired side exhaust ports each have an outside edge in the sheet
width direction that is substantially aligned in the sheet width
direction with an outside edge of a corresponding one of the paired
outside rollers in the sheet width direction, and the paired side
exhaust ports each have an inside edge in the sheet width direction
that is located inside in the sheet width direction from an inside
edge of a corresponding one of the paired outside rollers in the
sheet width direction.
8. The sheet stacking device according to claim 6, wherein the
airflows generated by the airflow generator are blown out from the
respective paired side exhaust ports toward regions of the lower
surface of the sheet that are being located downstream of the
respective pairs of ejection rollers in the conveyance
direction.
9. An image forming apparatus comprising: the sheet stacking device
according to claim 1; and an image forming section configured to
form an image on the sheet.
Description
INCORPORATION BY REFERENCE
[0001] The present application claims priority under 35 U.S.C.
.sctn. 119 to Japanese Patent Application No. 2016-225060, filed on
Nov. 18, 2016. The contents of this application are incorporated
herein by reference in their entirety.
BACKGROUND
[0002] The present disclosure relates to a sheet stacking device
for sheet stacking and an image forming apparatus including the
sheet stacking device.
[0003] A sheet stacking device is known in general that ejects a
sheet after image formation onto an exit tray. An image forming
apparatus is also known that includes a sheet stacking device
including a mechanism that blows wind toward a sheet that is being
ejected.
SUMMARY
[0004] A sheet stacking device according to an aspect of the
present disclosure includes a sheet stacking section, pairs of
ejection rollers, an airflow generator, and an airflow guide. A
sheet is stacked on the sheet stacking section. The pairs of
ejection rollers eject the sheet toward the sheet stacking section.
The airflow generator generates airflows. The airflow guide guides
the airflows toward a lower surface of the sheet ejected from the
pair of ejection rollers toward the sheet stacking section. The
airflow guide has a center exhaust port and paired side exhaust
ports. The center exhaust port is located downstream of the pairs
of ejection rollers. An airflow generated by the airflow generator
is blown out from the center exhaust port toward a central part of
the lower surface of the sheet in a sheet width direction
perpendicular to a conveyance direction of the sheet. The paired
side exhaust ports are located on respective opposite sides of the
central exhaust port in the sheet width direction. Airflows
generated by the airflow generator are blown out from the
respective paired side exhaust ports toward respective sides of the
lower surface of the sheet. An amount of the airflow blown out from
the center exhaust port is larger than those of the airflows blown
out from the respective paired side exhaust ports.
[0005] An image forming apparatus according to another aspect of
the present disclosure includes an image forming section and the
above sheet stacking device. The image forming section forms an
image on the sheet.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] FIG. 1 is a perspective view illustrating an outer
appearance of an image forming apparatus including a sheet stacking
device according to an embodiment of the present disclosure.
[0007] FIG. 2 is a cross-sectional view schematically illustrating
an internal configuration of a main unit of the image forming
apparatus.
[0008] FIG. 3 is an enlarged perspective view schematically
illustrating an internal configuration of the sheet stacking
device.
[0009] FIG. 4 is a side view illustrating a configuration of the
sheet stacking section and a vicinity thereof.
[0010] FIG. 5 is a schematic diagram illustrating a configuration
of an airflow generator and a duct.
[0011] FIG. 6 is an enlarged cross-sectional view of the sheet
stacking device in a state in which an airflow is blown toward a
sheet.
[0012] FIG. 7 is a perspective view of the sheet in a situation in
which airflows are blown toward the sheet.
[0013] FIG. 8 is an enlarged cross-sectional view of the sheet
stacking device in a situation in which failure in sheet ejection
occurs.
DETAILED DESCRIPTION
[0014] The following describes an embodiment of the present
disclosure in detail with reference to the accompanying drawings.
FIG. 1 is a perspective view illustrating an outer appearance of an
image forming apparatus S including a post-printing processing unit
5 according to an embodiment of the present disclosure. FIG. 2 is a
cross-sectional view schematically illustrating an internal
configuration of a main unit 1 of the image forming apparatus S.
The main unit 1 of the image forming apparatus S refers to a
so-called in-body ejection type monochrome copier. The main unit 1
of the image forming apparatus S may be a color copier, a printer,
a facsimile machine, or a multifunction peripheral. The
multifunction peripheral has any of functions of a color copier, a
printer, and a facsimile machine.
[0015] As illustrated in FIG. 1, the image forming apparatus S
includes the main unit 1 and the post-printing processing unit 5.
The main unit 1 performs image formation on a sheet P. The
post-printing processing unit 5 is disposed next to the main unit
1. The post-printing processing unit 5 includes a post-printing
processing section. The post-printing processing section performs
specific post-printing processing on a sheet P or a sheet set
(sheet sheaf) subjected to image formation. The post-printing
processing refers to for example at least one of punching,
stapling, folding, and aligning. Punching refers to processing to
punch a binding hole in the sheet P. Stapling refers to processing
to staple the sheet set. Folding refers to processing to fold the
sheet P. Aligning refers to processing to shift or align the sheet
P in width.
[0016] The main unit 1 includes a main unit casing 100, an image
scanning section 2a, an auto document feeder (ADF) 2b, and an
operation section 10. The image scanning section 2a is disposed
above the main unit casing 100. The auto document feeder 2b is
disposed on the upper surface of the image scanning section 2a. The
operation section 10 is mounted on a front surface of the image
scanning section 2a. The main unit casing 100 accommodates in the
interior thereof a sheet feed section 3a, a conveyance path 3b, an
image forming section 4a, a fixing section 4b, and a sheet ejecting
section 3c (see FIG. 2).
[0017] The operation section 10 receives user input for various
settings and operation instructions to the image forming apparatus
S. The operation section 10 includes a numeric keypad 11, a start
key 12, and a touch panel 13. The numeric keypad 11 receives
numeric input. The numeric keypad 11 receives for example setting
of the number of copies. The start key 12 receives input of an
instruction to execute a copy operation. The touch panel 13
displays various operation keys and guidance.
[0018] The auto document feeder 2b automatically feeds a document
sheet that is a copy target toward a predetermined first document
scanning position. The predetermined first document position is
located at a position where first contact glass 24 is mounted. In a
situation in which a user loads a document sheet on a predetermined
second document scanning position using the hand, the auto document
feeder 2b is opened upward. The predetermined second document
position is located at a position where second contact glass 25 is
mounted. The auto document feeder 2b includes a document teed tray
21, a document conveyance section 22, and a document exit tray 23.
The document sheet is loaded on the document feed tray 21. The
document conveyance section 22 conveys the document sheet via an
auto document scanning position. The document sheet after being
scanned is ejected onto the document exit tray 23.
[0019] The image scanning section 2a has a box casing shape. The
first contact glass 24 and the second contact glass 25 are fitted
in the upper surface of the image scanning section 2a. The first
contact glass 24 is glass for scanning the document sheet
automatically fed from the auto document feeder 2b. The second
contact glass 25 is glass for scanning the document sheet loaded
using the hand. The image scanning section 2a optically scans an
image of the document sheet.
[0020] As illustrated in FIGS. 1 and 2, the sheet feed section 3a
in the main unit casing 100 includes a plurality of cassettes 31.
The cassettes 31 include for example a first cassette 31A, a second
cassette 31B, a third cassette 31C, and a fourth cassette 31D
arranged in four stages. The first to fourth cassettes 31A to 31D
are disposed in descending order from above. The cassettes 31 each
accommodate sheets P having a specific size. The specific size
refers to for example A4 size or B4 size. Alternative examples of
the specific size include A-type sheet size such as A4 size and
B-type sheet size such as B4 size. The cassettes 31 each
accommodate a specific type of sheets P. The specific type of
sheets P refers to for example copy paper, recycled paper, thick
paper, or viewgraphs. A plurality of sheet feed rollers 32 that are
driven to rotate are each provided for a corresponding one of the
cassettes 31. The sheet feed rollers 32 include for example a first
sheet feed roller 32A, a second sheet feed roller 32B, a third
sheet feed roller 32C, and a fourth sheet feed roller 32D. The
first sheet feed roller 32A feeds one at a time the sheets P
accommodated in the first cassette 31A to the conveyance path 3b.
The second sheet feed roller 32B feeds one at a time the sheets P
accommodated in the second cassette 31B to the conveyance path 3b.
The third sheet feed roller 32C feeds one at a time the sheets P
accommodated in the third cassette 31C to the conveyance path 3b.
The fourth sheet feed roller 32D feeds one at a time the sheets P
accommodated in the fourth cassette 31D to the conveyance path
3b.
[0021] The conveyance path 3b is a conveyance path through which
the sheet P is conveyed in the main unit casing 100 from the sheet
feed section 3a to an in-body ejection tray 33. The conveyance path
3b is also a conveyance path through which the sheet P is conveyed
in the main unit casing 100 from the sheet feed section 3a to the
post-printing processing unit 5. A guide plate, conveyance roller
pairs 34, and a registration roller pair 35 are provided on the
conveyance path 3b. The guide plate guides the sheet P. The
conveyance roller pairs 34 rotate to convey the sheet P toward the
image forming section 4a. The conveyance roller pairs 34 include a
plurality of conveyance roller pairs such as a first conveyance
roller pair 34A, a second conveyance roller pair 34B, and a third
conveyance roller pair 34C. The registration roller pair 35
temporarily stops the sheet P before the image forming section 4a
and feeds the sheet P to the image forming section 4a in
synchronization with toner image transfer.
[0022] The image forming section 4a generates a toner image and
transfers the toner image onto the sheet P. That is, the image
forming section 4a forms an image on the sheet P. The image forming
section 4a includes a photosensitive drum 41, a charger 42, an
exposure device 43, a developing device 44, a transfer roller 45,
and a cleaner 46. The charger 42, the exposure device 43, the
developing device 44, the transfer roller 45, and the cleaner 46
are disposed around the photosensitive drum 41.
[0023] The photosensitive drum 41 forms an electrostatic latent
image and an toner image on the circumferential surface of the
photosensitive drum 41 by rotating about a shaft of the
photosensitive drum 41. The charger 42 uniformly charges the
surface of the photosensitive drum 41. The exposure device 43
includes a laser light source and an optical device such as a
mirror or a lens. The exposure device 43 irradiates the
circumferential surface of the photosensitive drum 41 with a laser
beam L based on image data of the image of the document sheet to
form an electrostatic latent image. The developing device 44
supplies toner to the circumferential surface of the photosensitive
drum 41 to develop the electrostatic latent image formed on the
photosensitive drum 41. The transfer roller 45 forms a transfer nip
part in cooperation with the photosensitive drum 41 into a toner
image. Transfer bias is applied to the transfer roller 45. The
toner image on the photosensitive drum 41 is transferred to the
sheet P passing through the transfer nip part. The cleaner 46
includes a cleaning roller and cleans the circumferential surface
of the photosensitive drum 41 after toner image transfer.
[0024] The fixing section 4b fixes to the sheet P the toner image
having been transferred to the sheet P. The fixing section 4b
includes a heating roller 47 and a pressure roller 48. The heating
roller 47 includes a heating element therein. The pressure roller
48 is in press contact with the heating roller 47 to form a fixing
nip. When the sheet P to which the toner image has been transferred
passes through the fixing nip, toner of the toner image is heated
and melt. As a result, the toner image is fixed to the sheet P. The
sheet P having being subjected to fixing is fed to the sheet
ejecting section 3c.
[0025] The sheet ejecting section 3c includes an out-body ejection
roller pair 36A and an in-body ejection roller pair 36B. The
out-body ejection roller pair 36A feeds the sheet P subjected to
image formation toward the post-printing processing unit 5. The
in-body ejection roller pair 36B feeds the sheet P subjected to
image formation toward the in-body ejection tray 33. The out-body
ejection roller pair 36A and the in-body ejection roller pair 36B
each are driven to rotate in an ejection operation to eject the
sheet out of the main unit casing 100. The sheet ejecting section
3c further includes a switch lever 37 that switches a feed
direction of the sheet P. The switch lever 37 turns to guide the
sheet P toward an ejection destination specified through the
operation section 10.
[0026] The post-printing processing unit 5 (sheet stacking device)
stacks the sheet P after performing specific post-printing
processing. The post-printing processing unit 5 includes a
post-printing processing unit casing 500 (casing) and a
post-printing processing section. The post-printing processing unit
casing 500 is disposed next to the main unit casing 100. The
post-printing processing section is disposed in the interior of the
post-printing processing unit casing 500 and performs the
post-printing processing on the sheet P. FIG. 3 is an enlarged
perspective view schematically illustrating an internal
configuration of the post-printing processing unit 5.
[0027] The post-printing processing unit 5 includes a shaft 51,
ejection rollers 52 (ejection roller pairs), driven rollers 53
(upper ejection rollers), a main exit tray 54 (sheet stacking
section), and a sub-exit tray 55.
[0028] The post-printing processing unit casing 500 has a side
surface facing the main unit casing 100 and having an unillustrated
conveyance inlet. The post-printing processing unit casing 500
receives the sheet P subjected to image formation through the
conveyance inlet. The post-printing processing unit casing 500 has
a left surface having a main conveyance outlet and a sub-conveyance
outlet from each of which the sheet P is ejected out of the
post-printing processing unit casing 500. The left side surface of
the post-printing processing unit casing 500 is located opposite to
the side surface facing the main unit casing 100. The main exit
tray 54 and the sub-exit tray 55 are mounted in correspondence with
the main conveyance outlet and the sub-conveyance outlet,
respectively, on the left side surface of the post-printing
processing unit casing 500 (see FIG. 1).
[0029] The main exit tray 54 is mounted on the post-printing
processing unit casing 500. The main exit tray 54 is a tray on
which a sheet P or a sheet set is stacked. The sheet P or the sheet
set is for example subjected to stapling, shifting, and width
aligning and then ejected onto the main exit tray 54 by the
ejection rollers 52. The main exit tray 54 has an inclined surface
54a ascending downstream in a conveyance direction DP of the sheet
P. The inclined surface 54a increases in height downstream in the
conveyance direction DP of the sheet P.
[0030] The sub-exit tray 55 is a tray on which a sheet P ejected
from the sub-conveyance outlet is stacked. The sub-exit tray 55 is
spaced above the main exit tray 54. A sheet P having been conveyed
into the post-printing processing unit casing 500 is selectively
ejected onto either the sub-exit tray 55 or the main exit tray 54.
For example, either or both a sheet P not subjected to any
post-printing processing in the post-printing processing unit 5 and
a sheet P subjected to only punching are stacked on the sub-exit
tray 55.
[0031] The ejection rollers 52 are supported to the post-printing
processing unit casing 500 in a rotatable manner. The ejection
rollers 52 are supported through the shaft 51 in the present
embodiment. The shaft 51 is supported to the post-printing
processing unit casing 500 through a unillustrated bearing. The
ejection rollers 52 convey in a predetermined conveyance direction
(leftward) the sheet P having been conveyed into the post-printing
processing unit casing 500 from the sheet ejecting section 3c of
the main unit 1. The ejection rollers 52 eject the sheet P toward
the main exit tray 54. Specifically, the ejection rollers 52 eject
the sheet P, which has been conveyed into the post-printing
processing unit casing 500 from the sheet ejecting section 3c of
the main unit 1, toward the main exit tray 54. Note that the
ejection rollers 52 include four ejection rollers 52 spaced from
one another in a sheet width direction (front-back direction) W in
the present embodiment, as illustrated in FIG. 3. It is only
required in the present disclosure that at least two ejection
rollers 52 are provided. Four or more ejection rollers may be
disposed in an alternative embodiment. The ejection rollers 52 in
plural number are spaced from one another in the sheet width
direction W. The ejection rollers 52 includes two ejection rollers
(paired inside ejection rollers) 52a and paired ejection rollers
(paired outside ejection rollers) 52b. The two ejection rollers 52a
are disposed between the paired ejection rollers 52b. The paired
ejection rollers 52b include a first ejection roller (first lower
ejection roller) 521 and a second ejection roller (second lower
ejection roller) 522. The sheet width direction W refers to a
direction perpendicular to the conveyance direction DP (see FIG. 6)
of the sheet P ejected from the ejection rollers 52 (nip parts 56)
toward the main exit tray 54. The sheet width direction W is
parallel to the sheet surface P1.
[0032] The driven rollers 53 are supported to the post-printing
processing unit casing 500 on the ejection rollers 52 in a
rotatable manner. The driven rollers 53 are supported to the
post-printing processing unit casing 500 on the ejection rollers 52
in a rotatable manner. Respective nip parts 56 through which the
sheet P passes are formed between the driven rollers 53 and the
ejection rollers 52. Some of the ejection rollers 52 are each
opposite to a corresponding one of the driven rollers 53. The nip
parts 56 are formed between the ejection rollers 52 and the driven
rollers 53 opposite thereto. Two nip parts 56 are formed in the
present embodiment. The driven rollers 53 are spaced from one
another in the sheet width direction W. In the present embodiment,
the driven rollers 53 are spaced from one another in the front-back
direction. The respective nip parts 56 are formed between the
ejection rollers 52 and the driven rollers 53 opposite thereto. The
sheet P passes through the nip parts 56. Specifically, the sheet P
passes through the nip parts 56 and is ejected toward the main exit
tray 54.
[0033] An unillustrated conveyance roller and an unillustrated
driven roller each for ejecting the sheet P onto the sub-exit tray
55 are further provided in the interior of the post-printing
processing unit casing 500.
[0034] The post-printing processing unit 5 further includes a first
fan 71 (airflow generator, first airflow generator), a second fan
72 (airflow generator, second airflow generator), and a duct 73
(airflow guide). FIG. 4 is a side view illustrating a configuration
of the main exit tray 54 of the post-printing processing unit 5 and
the vicinity thereof. FIG. 5 is a schematic diagram illustrating a
configuration of the first and second fans 71 and 72 and the duct
73. FIG. 6 is an enlarged cross-sectional view of the post-printing
processing unit 5 in a state in which airflows DF are blown toward
the sheet P.
[0035] The first and second fans 71 and 72 each generate an airflow
DF blowing toward the sheet P. The first and second fans 71 and 72
each are a known sirocco fan in the present embodiment. As
illustrated in FIGS. 5 and 6, the first and second fans 71 and 72
are disposed below the ejection rollers 52 in the post-printing
processing unit casing 500 and spaced from each other in the
front-back direction in the present embodiment. Note that the first
fan 71 disposed in front is illustrated in FIG. 6. The second fan
72 is spaced from the first fan 71 in the rear of the first fan 71
in FIG. 6. The first and second fans 71 and 72 each have an air
outlet open upward.
[0036] The duct 73 is disposed in the interior of the post-printing
processing unit casing 500. The duct 73 communicates the first and
second fans 71 and 72 with a space above the main exit tray 54. The
duct 73 guides the airflows DF toward the downwardly facing sheet
surface P1 of the sheet P ejected from the ejection rollers 52 (nip
parts 56) toward the main exit tray 54. The sheet surface P1 is a
surface of the sheet P that faces downward.
[0037] The duct 73 has a center exhaust port 61 and parried side
exhaust ports 62 and includes a first duct 73J and a second duct
73K. The center exhaust port 61 and the side exhaust ports 62 are
located below the ejection rollers 52, as illustrated in FIGS. 3
and 4. The center exhaust port 61 and the side exhaust ports 62 are
located above the base end of the main exit tray 54. The center
exhaust port 61 and the side exhaust ports 62 are located in the
left side surface of the post-printing processing unit casing 500.
The center exhaust port 61 and the side exhaust ports 62 are
aligned with one another in the sheet width direction W. The center
exhaust port 61 is located between the side exhaust ports 62. The
center exhaust port 61 and the side exhaust ports 62 are located
below the ejection rollers 52.
[0038] An airflow D61 is blown out from the center exhaust port 61
toward a central portion P11 of the sheet surface P1 of the sheet
P, which is ejected by the ejection rollers 52, in the sheet width
direction (front-back direction) W. The side exhaust ports 62 are
located on respective opposite sides of the center exhaust port 61
in the sheet width direction W. The side exhaust ports 62 are
spaced from each other in the sheet width direction W. Airflows D62
are blown out from the respective side exhaust ports 62 toward
respective sides of the sheet surface P1 of the sheet P in the
sheet width direction W. One of the airflows D62 is blown out from
a corresponding one of the side exhaust ports 62 toward a part of
the sheet surface P1 of the sheet P ejected by the ejection rollers
52 that is located on one side thereof in the sheet width direction
W. The other of the airflows D62 is also blown out from the other
of the side exhaust ports 62 toward another part of the sheet
surface P1 of the sheet P ejected by the ejection rollers 52 that
is located on the opposite side thereof in the sheet width
direction W. The respective airflows D62 are blown out in
substantially the same direction from one (first side exhaust port
621) and the other (second side exhaust port 622) of the side
exhaust ports 62. When the center exhaust port 61 and the side
exhaust ports 62 are viewed from above, a direction in which the
airflow D61 is blown out from the center exhaust port 61 and
directions in which the airflows D62 are blown out from the
respective side exhaust ports 62 are parallel to the conveyance
direction DP of the sheet P. However, as will be described later,
the direction in which the airflow D61 is blown out from the center
exhaust port 61 and the directions in which the airflows D62 are
blown out from the respective side exhaust ports 62 each cross the
conveyance direction DP of the sheet P at a predetermined angle as
viewed in a horizontal direction (front-back direction).
[0039] Positions of the center exhaust port 61 and the side exhaust
ports 62 will be described further in detail below with reference
to FIG. 4. As described above, the four ejection rollers 52 are
provided in the present embodiment. The center exhaust port 61 is
located below a region E between the two ejection rollers 52a. The
side exhaust ports 62 include the first side exhaust port 621 and
the second side exhaust port 622. The side exhaust ports 62 are
each located below a corresponding one of the ejection rollers 52b
of the pair of ejection rollers 52b. Specifically, the first side
exhaust port 621 is located blow the first ejection roller 521 and
the second side exhaust port 622 is located blow the second
ejection roller 522.
[0040] The side exhaust ports 62 each have an outside edge in the
sheet width direction W that is substantially aligned in the sheet
width direction W with an outside edge of a corresponding one of
the ejection rollers 52b of the pair of ejection rollers 52b in the
sheet width direction W. The side exhaust ports 62 each have an
inside edge in the sheet width direction W that is located more
inside in the sheet width direction W than an inside edge of a
corresponding one of the ejection rollers 52b of the pair of
ejection rollers 52b in the sheet width direction W. In other
words, as illustrated in FIG. 4, the side exhaust ports 62 each
extend inside of a corresponding one of the ejection rollers 52b of
the pair of ejection rollers 52b in the sheet width direction W.
Specifically, the first side exhaust port 621 has a first outside
edge L1 located at an outside end thereof in the sheet width
direction W and a first inside edge M1 located at an inside end
thereof in the sheet width direction W. The second side exhaust
port 622 has a second outside edge L2 located at an outside end
thereof in the sheet width direction W and a second inside edge M2
located at an inside end thereof in the sheet width direction W.
The first ejection roller 521 has a third outside edge Q1 located
at an outside end thereof in the sheet width direction W and a
third inside edge R1 located at an inside end thereof in the sheet
width direction W. The second ejection roller 522 has a fourth
outside edge Q2 located at an outside end thereof in the sheet
width direction W and a fourth inside edge R2 located at an inside
end thereof in the sheet width direction W. The first outside edge
L1 is aligned in the sheet width direction W with the third outside
edge Q1. The second outside edge L2 is aligned in the sheet width
direction W with the fourth outside edge Q2. The first inside edge
M1 is located inside of the third inside edge R1 in the sheet width
direction W. The second inside edge M2 is located inside of the
fourth inside edge R4 in the sheet width direction W. The phrase
outside in the sheet width direction W refers to a location close
to a specific point in the sheet width direction W. The phrase
inside side in the sheet width direction W refers to a location
away from the specific point in the sheet width direction W. The
specific location refers to a central part of a region between the
two nip parts 56 in the sheet width direction W.
[0041] The first duct 73J divides an airflow generated by the first
fan 71 into two airflows and guides the respective airflows to the
center exhaust port 61 and one (second side exhaust port 622) of
the side exhaust ports 62.
[0042] The second duct 73K divides an airflow generated by the
second fan 72 into two airflows and guides the respective airflows
to the center exhaust port 61 and the other (first side exhaust
port 621) of the side exhaust ports 62.
[0043] Respective parts of the airflows generated by the first and
second fans 71 and 72 are merged together. Accordingly, the amount
of the airflow D61 blown out from the center exhaust port 61 is
larger than those of the airflows D62 blown out from the respective
side exhaust ports 62. As such, the amount of the airflow D61 blown
out from the center exhaust port 61 is set larger than those of the
airflows D62 blown out from the respective side exhaust ports 62.
Specifically, the amount of the airflow D61 blown out from the
center exhaust port 61 is set larger than that of the airflow D62
blown out from the first side exhaust port 621 and that of the
airflow D62 blown out from the second side exhaust port 622.
[0044] The airflow generated by the first fan 71 and the airflow
generated by the second fan 72 are each blown out from the center
exhaust port 61 and a corresponding one of the side exhaust ports
62 in the present embodiment. Specifically, the airflow generated
by the first fan 71 and the airflow generated by the second fan 72
are each blown out leftward from the center exhaust port 61 and a
corresponding one of the side exhaust ports 62. The airflow
generated by the first fan 71 and the airflow generated by the
second fan 72 are blown at specific angles relative the conveyance
direction DP of the sheet P. The opening length of the center
exhaust port 61 in the sheet width direction (front-back direction)
W is double the opening length of each of the side exhaust ports 62
in the sheet width direction W. The opening length in a height
direction (up-and-down direction) of the center exhaust port 61 is
a half of the opening length of each of the side exhaust ports 62
in the height direction. The center exhaust port 61 has an upper
edge aligned in the height direction with the upper edges of the
respective side exhaust ports 62. The center exhaust port 61 has a
lower edge located above the lower edges of the respective side
exhaust ports 62. In the above configuration, the amount of the
airflow D61 blown out from the center exhaust port 61 is larger
than the amounts of the airflows D62 blown out from the respective
side exhaust ports 62.
[0045] Specifically, the center exhaust port 61 and the side
exhaust ports 62 are directed (see FIG. 3) such that a blowing
direction of the airflow D61 blown out from the center exhaust port
61 and blowing directions of the airflows D62 blown out from the
respective side exhaust ports 62 ascend downstream in the
conveyance direction DP and cross the conveyance direction DP of
the sheet P when viewed from the front. The blowing direction of
the airflow D61 is a direction indicated by an arrow D61 in FIG. 3.
The blowing directions of the respective airflows D62 are
directions indicated by respective arrows D62 in FIG. 3. The phrase
the blowing direction of the airflow D61 and the blowing directions
of the airflows D62 cross the conveyance direction DP of the sheet
P refers to a route of the sheet P moving in the conveyance
direction DP crossing a first imaginary line extending from the
center exhaust port 61 in the blowing direction of the airflow D61
and second imaginary lines extending from the respective side
exhaust ports 62 in the blowing directions of the respective
airflows D62. The phrase the directions ascend downstream in the
conveyance direction DP refers to the airflows D61 and D62 each
flowing in a specific direction. The specific direction refers to a
direction inclined upward at an acute angle relative to a
downstream direction of the conveyance direction DP. Furthermore,
the center exhaust port 61 and the side exhaust ports 62 are
directed such that an angle G made by the conveyance direction DP
of the sheet P and the blowing direction of the airflow D61 blown
out from the center exhaust port 61 is larger than an angle made by
the conveyance direction DP of the sheet P and the blowing
directions of the airflows D62 blown out from the respective side
exhaust ports 62. Specifically, the center exhaust port 61 and the
side exhaust ports 62 are directed such that the angle G is greater
than a first blowing angle G1 and a second blowing angle G2. The
first blowing angle G1 refers to an angle made by the conveyance
direction DP of the sheet P and the blowing direction of the
airflow D62 blown out from one of the side exhaust ports 62. The
blowing second angle G2 refers to an angle made by the conveyance
direction DP of the sheet P and the blowing direction of the
airflow D62 blown out from the other of the side exhaust ports 62.
In other words, the blowing direction of the airflow D61 blown out
from the center exhaust port 61 ascends downstream in the
conveyance direction DP at an angle larger than the blowing
directions of the airflows D62 blown out from the respective side
exhaust ports 62. In the above configuration, the airflow D61 blown
out from the center exhaust port 61 strikes on a part of the sheet
surface P1 of the sheet P located closer in height to the ejection
rollers 52 than a part of the sheet surface P1 thereof on which the
airflows D62 blown out from the respective side exhaust ports 62
strike.
[0046] The main exit tray 54 has the inclined surface 54a ascending
downstream in the conveyance direction of the sheet P, as described
above. The respective side exhaust ports 62 are directed such that
the first and second blowing angles G1 and G2 between the
conveyance direction DP of the sheet P and the blowing directions
of the airflows D62 blown out from the respective side exhaust
ports 62 are larger than a blowing angle G3 made by the inclined
surface 54a of the main exit tray 54 and the conveyance direction
DP of the sheet P. Specifically, the respective side exhaust ports
62 are directed such that the first and second blowing angles G1
and G2 each are larger than the blowing angle G3. In other words,
the blowing directions of the airflows D62 blown out from the
respective side exhaust ports 62 ascend downstream in the
conveyance direction DP at a larger angle than inclination of the
inclined surface 54a of the main exit tray 54. That is, angles of
elevation of the blowing directions of the airflows D62 blown out
from the respective side exhaust ports 62 are larger than that of
the inclined surface 54a of the main exit tray 54.
[0047] FIG. 7 is a perspective view of the sheet P in a situation
in which the airflows DF including the airflow D61 and the airflows
D62 is blown toward the sheet P. Note that the conveyance direction
of the sheet P ejected by the ejection rollers 52 and the driven
rollers 53 is indicated by an arrow DP in FIG. 7. FIG. 8 is an
enlarged cross-sectional view of the post-printing processing unit
5 in a situation in which failure in sheet ejection occurs.
[0048] The sheet P is liable to be charged when being conveyed into
the main unit 1 and the post-printing processing unit 5 of the
image forming apparatus S. Accordingly, when the sheet P having the
sheet surface P1 that has been electrostatically charged is ejected
by the ejection rollers 52, a leading edge P2 of the sheet P is
attracted to the main exit tray 54, as illustrated in FIG. 8. As a
result, the sheet P cannot be stacked on the main exit tray 54 in a
favorable fashion, which may cause failure such as a jam.
[0049] The duct 73 has the three exhaust ports 61 and 62 through
which the airflows are blown out in the present embodiment in order
to obviate failure as above. The airflows blown out from the duct
73 strike on the sheet surface P1 of the sheet P facing downward
and enters a space between the sheet P and the main exit tray 54,
as indicated by an arrow DF in FIG. 6.
[0050] The amount of the airflow (arrow D61 in FIG. 7) blown out
from the center exhaust port 61 is larger than those of the
airflows (arrows D62 in FIG. 7) blown out from the respective side
exhaust ports 62. A central part of the sheet P having passed
through the nip parts 56 warps upward and in the conveyance
direction, as illustrated in FIG. 7. As a result, remarkable
resilience can be imparted to the sheet P ejected onto the main
exit tray 54 in a secure manner, thereby achieving sheet alignment
in a secure manner. Furthermore, an air layer is formed between
sheets P in continuous printing, with a result that adhesion (or
sticking) between the sheets P can be reduced.
[0051] In particular, the airflow D61 blown out from the center
exhaust port 61 ascends downstream in the conveyance direction DP
at a larger angle than the airflows D62 blown out from the
respective side exhaust ports 62 in the present embodiment, as
illustrated in FIGS. 3 and 7. In the above configuration, the
airflow D61 blown out from the center exhaust port 61 strikes on
the sheet surface P1 at a steeper angle than the airflows D62.
Therefore, the sheet P having passed through the nip parts 56 can
readily warp. The central part of the sheet P warps upward and in
the conveyance direction of the sheet P.
[0052] Furthermore, the blowing directions of the airflows D62
blown out from the respective side exhaust ports 62 ascend
downstream in the conveyance direction DP at a larger angle than
the inclination of the inclined surface 54a of the main exit tray
54. In the above configuration, a situation in which the airflows
D62 blown out from the respective side exhaust ports 62 strike hard
on the inclined surface 54a of the main exit tray 54 before
striking on the sheet surface P1 of the sheet P can be prevented.
Accordingly, airflow turbulence can hardly occur between the
ejected sheet P and the main exit tray 54, thereby achieving
improved sheet alignment.
[0053] Note that the first and second fans 71 and 72 each start
blowing the airflows DF before the leading edge P2 of the sheet P
passes through the respective nip parts 56 between the ejection
rollers 52 and the driven rollers 53 in the present embodiment.
Furthermore, the first and second fans 71 and 72 each stop
generating the airflows DF before a trailing edge P3 of the sheet P
passes through the nip parts 56. In the above configuration, the
leading edge P2 of the sheet P can warp in a secure manner. The
airflows strike not so hard on the trailing edge P3 of the sheet P
having passed through the nip parts 56. As a result, stacking
failure caused due to a lift of the trailing edge P3 of the sheet P
can be avoided. The leading edge P2 of the sheet P refers to an
edge of the sheet P located downstream in the conveyance direction
DP. The trailing edge P3 of the sheet P refers to an edge of the
sheet P located upstream in the conveyance direction DP.
[0054] As illustrated in FIG. 5, the two fans 71 and 72 are
provided in the present embodiment. When the airflows of the two
fans 71 and 72 are merged together in the duct 73, the airflow D61
having a large amount can be blown out from the center exhaust port
61. Even when one of the fans 71 and 72 stops driving, the airflow
D61 blown out from the center exhaust port 61 can be ensured.
[0055] As illustrated in FIG. 4, the center exhaust port 61 is
located below the region E between the two ejection rollers 52a
that are spaced from each other in middle in the sheet width
direction W among the four ejection rollers 52. In the above
configuration, the sheet P can readily warp upward by blowing the
strong airflow D61 from the center exhaust port 61 between the two
ejection rollers 52a, as illustrated in FIG. 7.
[0056] The side exhaust ports 62 are located blow the respective
ejection rollers 52b disposed outside in the sheet width direction
W among the four ejection rollers 52 (see FIG. 4). In the above
configuration, the airflows D62 from the respective side exhaust
ports 62 strike on respective specific regions of the sheet surface
P1. The specific regions each refer to a region of the sheet
surface P1 that is being located downstream in the conveyance
direction DP of a region of the sheet surface P1 that is being
nipped by a corresponding one of the ejection rollers 52b located
outside in the sheet width direction W. In other words, airflows
D62 are blown from the respective side exhaust ports 62 toward
regions of the sheet surface P1 that are being located downstream
of the respective ejection rollers 52 in the conveyance direction
DP. The regions that are being nipped by the respective ejection
rollers 52b refer in other words to regions of the sheet surface P1
that are in contact with the respective ejection rollers 52b. In
the above configuration, a situation in which the ejected sheet P
is wobbled and skewed by the airflows D62 blown out from the
respective side exhaust ports 62 can be prevented.
[0057] The outside edges (first and second outside edges L1 and L2)
of the respective side exhaust ports 62 in the sheet width
direction W are substantially aligned in the sheet width direction
W with the outside edges (third and fourth outside edges Q1 and Q2)
of the respective ejection rollers 52b in the sheet width direction
W that are disposed outside in the sheet width direction W. The
inside edges (first and second inside edges M1 and M2) of the
respective side exhaust ports 62 in the sheet width direction W are
each located inside in the sheet width direction W from the inside
edge (third and fourth inside edges R1 or R2) of a corresponding
one of the corresponding ejection rollers 52b in the sheet width
direction W. In the above configuration, respective parts of the
airflows D62 blown out from the side exhaust ports 62 flow inside
in the sheet width direction W to be merged with the airflow D61
blown out from the center exhaust port 61. Accordingly, the sheet P
having passed through the nip parts 56 can warp upward and in the
conveyance direction in a secure manner.
[0058] One embodiment of the present disclosure has been described
so far in detail. In the above configuration, remarkable resilience
can be imparted to the sheet P being ejected onto the main exit
tray 54, thereby achieving sheet alignment in a secure manner.
Furthermore, an air layer is formed between sheets P, with a result
that adhesion (or sticking) between the sheets P can be reduced.
Note that the present disclosure is not limited to the above
embodiment. The present disclosure can be changed for example to
any of the following alterations.
[0059] (1) The above embodiment describes the post-printing
processing unit 5 as an example of the sheet stacking device, which
however should not be taken to limit the present disclosure. The
present disclosure is adaptable to any device that can eject and
stack a sheet P on which an image has been formed.
[0060] (2) The above embodiment describes the post-printing
processing unit 5 having the single center exhaust port 61 and the
two side exhaust ports 62, which however should not be taken to
limit the present disclosure. The post-printing processing unit 5
may have a single center exhaust port 61 and four or any other
plural number of side exhaust ports 62 located outside of the
center exhaust port 61 in the sheet width direction W.
[0061] (3) The four ejection rollers 52 are provided in the above
embodiment. However, two pairs of ejection rollers 52 and driven
rollers 53 may be spaced in the front-back direction so as to nip
the central part of the sheet P in the sheet width direction W. In
the above configuration, it is possible that the center exhaust
port 61 is located below a region between the two pairs of the
rollers and the respective side exhaust ports 62 are located below
the respective two pairs of the rollers.
[0062] (4) The ejection rollers 52 and the driven rollers 53 in the
above embodiment correspond to the lower ejection rollers and the
upper ejection rollers, respectively, in the present disclosure.
However, it is possible that the ejection rollers 52 and the driven
rollers 53 may be the upper ejection rollers and the lower ejection
rollers, respectively, in the present disclosure.
* * * * *