U.S. patent application number 12/266302 was filed with the patent office on 2009-05-14 for post-processing apparatus and image forming system.
Invention is credited to Junichi FUJITA, Hisao Hosoya, Hiroto Ito, Kenji Kawatsu.
Application Number | 20090121421 12/266302 |
Document ID | / |
Family ID | 40622978 |
Filed Date | 2009-05-14 |
United States Patent
Application |
20090121421 |
Kind Code |
A1 |
FUJITA; Junichi ; et
al. |
May 14, 2009 |
POST-PROCESSING APPARATUS AND IMAGE FORMING SYSTEM
Abstract
A post-processing apparatus having therein a stacker that stocks
sheets temporarily and an ejection device that ejects a plurality
of sheets stacked on the stacker from the stacker wherein the
ejection device has an ejection claw that pushes up the plural
sheets and a moving device that moves the ejection claw along the
stacker, the ejection claw has a contact surface with which the
aforesaid plural sheets are brought into contact when the plural
sheets are pushed up, and the contact surface has plural
protrusions protruding toward the plural sheets.
Inventors: |
FUJITA; Junichi;
(Kokubunji-shi, JP) ; Hosoya; Hisao;
(Sagamihara-shi, JP) ; Ito; Hiroto; (Hachioji-shi,
JP) ; Kawatsu; Kenji; (Machida-shi, JP) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER;LLP
901 NEW YORK AVENUE, NW
WASHINGTON
DC
20001-4413
US
|
Family ID: |
40622978 |
Appl. No.: |
12/266302 |
Filed: |
November 6, 2008 |
Current U.S.
Class: |
271/264 |
Current CPC
Class: |
B65H 2301/42266
20130101; B65H 2301/4213 20130101; B42B 4/00 20130101; B65H 2404/73
20130101; B65H 2404/521 20130101; B42C 1/12 20130101; B65H 2801/27
20130101; B65H 31/3081 20130101 |
Class at
Publication: |
271/264 |
International
Class: |
B65H 5/00 20060101
B65H005/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 12, 2007 |
JP |
JP2007-293003 |
Claims
1. A post-processing apparatus comprising: a stacker which stocks a
sheet temporarily; and an ejection device which ejects a plurality
of sheets from the stacker on which the plurality of sheets have
been stacked, the ejection device comprising: an ejection claw
which pushes up the plurality of sheets; and a moving device which
moves the ejection claw along the stacker, wherein the ejection
claw comprises a contact surface with which the plurality of sheets
are brought into contact when the ejection claw moves and pushes up
the plurality of sheets by the moving device, and the contact
surface comprises a plurality of protrusions which protrudes toward
the plurality of sheets stacked on the stacker.
2. The post-processing apparatus of claim 1, wherein the plurality
of protrusions extend parallel to a width direction of the
plurality of sheets stacked on the stacker.
3. The post-processing apparatus of claim 2, wherein the ejection
claw is fixed to the moving device and at least a lateral surface
facing the moving device among both lateral surfaces of each of the
plurality of protrusions makes a prescribed angle with a bottom
surface of a recess between the plurality of protrusions adjacent
to each other, the recess being adjacent to the lateral
surface.
4. The post-processing apparatus of claim 1, wherein the ejection
device comprises a plurality of the moving devices arranged in a
direction perpendicular to an ejection direction of the plurality
of sheets stacked on the stacker.
5. The post-processing apparatus of claim 1, wherein a protrusion
positioned at an uppermost portion of the ejection claw among the
plurality of protrusions is taller than another protrusion of the
plurality of protrusions.
6. An image forming system comprising: an image forming apparatus
which conducts image forming on a sheet; and a post-processing
apparatus of claim 1 connected to the image forming apparatus.
7. The image forming system of claim 6, wherein the image forming
apparatus comprises a selecting device which selects a
post-processing operation to be conducted in the post-processing
apparatus.
8. The image forming system of claim 7, wherein each of the image
forming apparatus and the post-processing apparatus comprises an
information communicating device for communicating information
about the post-processing operation selected by the selecting
device.
Description
[0001] This application is based on Japanese Patent Application No.
2007-293003 filed on Nov. 12, 2007 in Japanese Patent Office, the
entire content of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] The present invention relates to a post-processing apparatus
having therein a stacker that stocks sheets temporarily and an
ejection device that ejects a plurality of sheets stacked on the
stacker and to an image forming system having therein the
post-processing apparatus.
[0003] There is known a post-processing apparatus wherein plural
image-recorded sheets ejected from an image forming apparatus are
collected in the form of a group of plural sheets to be outputted,
or sheets are collated for each copy and stapled by a stapler to be
outputted.
[0004] It is further known that a period of time required for
post-processing such as stapler processing in a post-processing
apparatus is generally longer than a period of time required for
image forming processing in an image forming apparatus.
[0005] Therefore, there is known a post-processing apparatus
wherein a stacker that stocks sheets temporarily is provided in the
post-processing apparatus to stack a prescribed number of
sheets.
[0006] As the post-processing apparatus of this kind, there is
known an apparatus wherein an ejection device that ejects stacked
plural sheets to an ejection tray and a stapler representing a
post-processing apparatus is provided, and plural sheets are pushed
up and ejected by an ejection claw fixed on the ejection device
(for example, Unexamined Japanese Patent Application Publication
No. 8-137151).
[0007] In the post-processing apparatus described in Unexamined
Japanese Patent Application Publication No. 8-137151, it is
possible to eject plural sheets (sheet bundle) to an ejection tray
or to a stapler, by pushing up plural sheets with an ejection claw
provided on the ejection device
[0008] However, with respect to a shape of the ejection claw, its
contact surface with a sheet is flat, excluding a protrusion on the
uppermost section, as illustrated in FIG. 1 (a). Therefore, in the
case of a poor fragile sheet or a curled sheet, in particular, the
contact portion side of the sheet contacting the ejection claw
tends to be shifted toward a tip portion of the ejection claw when
a sheet bundle is pushed up, and if it is shifted greatly, there is
a possibility that the contact portion side of the sheet contacting
the ejection claw climbs over the protrusion on the uppermost
section, causing conveyance abnormality, which has been a
problem.
[0009] Further, for example, when an ejection claw is arranged only
at a position corresponding to the width direction of a small-sized
sheet, if a large-sized sheet is tried to be ejected out,
resistance of conveyance is increased by curls on the end portion
of the large-sized sheet bundle, and the sheet is easily skewed. If
the sheet is skewed, there is a possibility that the contact
portion side of the sheet contacting the ejection claw climbs over
the protrusion on the uppermost section, causing conveyance
abnormality, which has been a problem.
[0010] The followings are aspects of the invention.
1. A post-processing apparatus comprising: a stacker which stocks a
sheet temporarily; and an ejection device which ejects a plurality
of sheets from the stacker on which the plurality of sheets have
been stacked, the ejection device comprising: an ejection claw
which pushes up the plurality of sheets; and a moving device which
moves the ejection claw along the stacker, wherein the ejection
claw comprises a contact surface with which the plurality of sheets
are brought into contact when the ejection claw moves and pushes up
the plurality of sheets by the moving device, and the contact
surface comprises a plurality of protrusions which protrudes toward
the plurality of sheets stacked on the stacker. 2. An image forming
system having therein an image forming apparatus that conducts
image forming on a sheet and a post-processing apparatus described
in the aforesaid Item 1 connected to the image forming
apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 (a) is a conceptual diagram describing a stacker and
an ejection device in a conventional embodiment and FIG. 1 (b) is
one in a present embodiment.
[0012] FIG. 2 is a diagram showing a post-processing apparatus and
an image forming system equipped with the post-processing
apparatus.
[0013] FIGS. 3 (a) and 3 (b) are schematic diagrams showing sheet
conveyance courses including the first conveyance path and the
second conveyance path.
[0014] FIG. 4 is a schematic diagram showing a sheet conveyance
course using the third conveyance path.
[0015] Each of FIGS. 5 (a) and 5 (b) is a detailed diagram of an
ejection claw fixed on an ejection belt.
[0016] Each of FIGS. 6 (a) and 6 (b) is a diagram of another
embodiment for a protrusion provided on an ejection claw.
[0017] FIG. 7 is a diagram of the fourth embodiment for a
protrusion provided on an ejection claw.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] Prior to the detailed description of the embodiment,
outlines of the present embodiment and of the conventional
embodiment will be described as follows, for easy understanding of
the description.
[0019] FIGS. 1 (a) and 1 (b) are conceptual diagrams describing a
stacker and an ejection device in a conventional embodiment and
those in a present embodiment.
[0020] FIG. 1 (a) is a conceptual diagram describing a conventional
stacker and a conventional ejection device, while, FIG. 1 (b) is a
conceptual diagram describing a stacker and an ejection device both
in the present embodiment.
[0021] In FIG. 1 (a), stacker 101 that stacks plural sheets
temporarily has stopper 103 that conducts alignment on the
conveyance direction side for sheets fed from the preceding
process, whereby, plural sheets are stacked while alignment of
sheets on the conveyance direction side is conducted (two-dot chain
lines).
[0022] Ejection device 102 that ejects a bundle of sheets (two-dot
chain lines) stacked on stacker 101 has ejection claw 104 that
pushes up bundle of sheets P1 (solid lines) in the direction of the
arrow to eject them toward the succeeding progress.
[0023] Contact surface 105 of ejection claw 104 with which a bundle
of sheets is brought into contact is flat, and tip portion 106 of
the ejection claw is slightly protrudent in the pushing up
direction.
[0024] The ejection claw 104 has no measures to prevent a bundle of
sheets from being shifted on contact surface 105 undesirably toward
tip portion 106, and only measures to prevent a bundle of sheets
from protruding from ejection claw 104 are represented by tip
portion 106 that is slightly protrudent in the pushing up
direction.
[0025] For this reason, when the bundle of sheets is pushed up in
the direction of the arrow, its portion on the side of contact with
ejection claw 104 tends to be bent, as illustrated, and in the case
of a non-rigid sheet or in the case of existence of a curl, in
particular, there is a possibility that the bundle of sheets is
shifted undesirably on the contact surface 105, and it runs on
protrusion 107 on the tip portion.
[0026] The foregoing means that the force toward protrusion 107 of
a tip portion by own weight of a bundle of sheets overcomes
frictional force between the bundle of sheets and contact surface
105, thus, the bundle of sheets is shifted to the protrusion 107
side.
[0027] As a result, when the bundle of sheets runs on the
protrusion 107 of the tip portion, there is caused conveyance
abnormality which has been a cause for the decline of reliability
and productivity.
[0028] In FIG. 1 (b), stacker 111 that stacks plural sheets
temporarily has stopper 113 that conducts alignment on the
conveyance direction side for sheets fed from the preceding
process, whereby, plural sheets are stacked while alignment of
sheets on the conveyance direction side is conducted (two-dot chain
lines).
[0029] Ejection device 112 that ejects plural sheets (two-dot chain
lines) stacked on stacker 111 from stacker 111 by pushing up them
has ejection claw 114 that pushes up plural sheets, namely, bundle
of sheets P1 (solid lines) in the direction of the arrow to eject
them toward the succeeding progress, and has ejection belt 56 that
is a moving device to move the ejection claw 114 in the direction
for pushing up along stacker 111.
[0030] Contact surface 115 of ejection claw 114 touched by the
bundle of sheets has protrusions 118, and tip portion 116 of
ejection claw 114 forms protrusion 117 that is taller than the
protrusions 118 in the direction (direction of the arrow) for
pushing up.
[0031] Owing to this, although bundle of sheets P1 tends to be bent
when it is pushed up, a contact side of the sheet contacting
ejection claw 114 (hereafter, a contact side of the sheet
contacting ejection claw 114 is described as a trailing edge of the
sheet) is caught by protrusions 118. Therefore, the trailing edge
of a sheet is restrained from sliding on contact surface 115 and
from being moved toward protrusion 117, even in the case of
existence of curls, in particular, thus, the bundle of sheets P1 is
prevented from being bent greatly.
[0032] Therefore, the bundle of sheets P1 can be prevented from
running on protrusion 117 of the aforesaid tip portion.
[0033] In other words, the bundle of sheets P1 is caused to be
caught by the contact surface 115 thereon, and thereby, a trailing
edge of the bundle of sheets P1 is prevented from being shifted
toward the protrusion 117, without relying on frictional force
between the bundle of sheets P1 and the contact surface 115 thereon
as in the past.
[0034] Owing to this, no conveyance abnormality is caused, and
reliability and productivity are improved.
[0035] Referring to the drawings, embodiments will be described as
follows, to which, however, the invention is not limited.
[0036] Incidentally, devices and members having the same functions
and forms as those in other drawings are given the same symbols as
those in other drawings.
[0037] FIG. 2 is a diagram showing a post-processing apparatus and
an image forming system equipped with the post-processing
apparatus.
[0038] Image forming system Z has therein image forming apparatus A
that records an image on a sheet and a post-processing apparatus B
that conducts post-processing on the sheet on which the image is
recorded by the image forming apparatus A.
[0039] First, the image forming apparatus A will be described.
[0040] The image forming apparatus A is one (for example, a copying
machine, a printer and a facsimile machine) that forms an image on
a sheet through an electrophotographic method, and it has image
forming section A1, document feeding device A2 and image reading
section A3.
[0041] Start-up of the image forming apparatus A starts document
feeding device A2 to operate.
[0042] The document feeding device A2 conveys documents to a
reading position one after another.
[0043] Then, the image reading section A3 reads a document conveyed
by the document feeding device A2 or an image of a document placed
on document table 9, and generates image signals.
[0044] Around drum-shaped photoreceptor 1 in the image forming
section A1, there are arranged charging unit 2 that charges
photoreceptor 1 uniformly, exposure unit 3 that gives exposure
based on the aforesaid image signals of an image of the document,
developing unit 4 that visualizes a latent image resulted from
exposure by using toner, transfer unit 5A that transfers a toner
image formed on the photoreceptor onto a sheet, separation unit 5B
that separates a sheet from photoreceptor 1, and cleaning unit 6
that removes toner remaining on photoreceptor 1, whereby, images
are formed on sheet S by these units of electrophotographic
process.
[0045] Sheet S is stored in sheet feed tray 7A, and sheet S is fed
from sheet feed tray 7A one by one, and a toner image on
photoreceptor 1 is transferred onto sheet S by transfer unit
5A.
[0046] Then, the toner image transferred onto sheet S passes
through fixing unit 8 to be subjected to fixing processing.
[0047] Then, the sheet S which has been subjected to the fixing
processing is ejected to post-processing apparatus B from sheet
ejection roller 7C.
[0048] In the case of two-sided image forming, the sheet S is
guided downward by switching gate 7D, and it passes through sheet
re-feed path 7E after being reversed inside out by a switchback, to
be fed to transfer unit 5A again where an image on the reverse side
is transferred.
[0049] Operation panel P representing a selection device for
selecting operations of post-processing conducted by
post-processing apparatus B has a touch panel (not shown), and it
displays various selection switches and information relating to
operations of post-processing on the touch panel.
[0050] For example, selection switches for sizes of sheets to be
used such as A4 and B4 and selection switches for operations of
post-processing such as, for example, sheet stacking processing and
staple processing, are displayed.
[0051] Then, various pieces of information from operations of
various types of selection switches are inputted in control device
C1.
[0052] Each of the image forming apparatus A and the
post-processing apparatus B has an information sending and
receiving device that sends and receives post-processing operation
information selected by the aforesaid post-processing operation
selecting switch that is a selection device which selects
operations of post-processing to be conducted in the
post-processing apparatus.
[0053] Communication device C11 of image forming apparatus A
conducting serial communication and communication device C21 of
post-processing apparatus B, both representing an information
sending and receiving device send and receive various types of
information relating to operations of post-processing each
other.
[0054] Control device C1 controls the aforesaid operations relating
to the image forming apparatus A.
[0055] Post-processing apparatus B will be described as
follows.
[0056] The post-processing apparatus B is an apparatus for
conducting various types of post-processing including staple
processing on sheet S fed in from the image forming apparatus
A.
[0057] The post-processing apparatus B is installed after its
position and height are adjusted so that an entrance portion for
sheet S may agree with an ejecting direction of ejection roller 7C
of image forming apparatus A, and the post-processing apparatus B
is driven in accordance with operations of the image forming
apparatus A.
[0058] A conveyance path for sheet S that is connected to the
downstream side of the sheet conveyance direction of paired
entrance rollers 11 in the aforesaid entrance portion is branched
into three ways including first conveyance path 100 on the upper
portion, second conveyance path 200 on the medium portion and third
conveyance path 300 on the lower portion.
[0059] Then, sheet S is fed to any one of the conveyance paths
through the selection of an angle of each of switching gates G1, G2
and G3.
[0060] The first conveyance path 100 causes sheet S to be ejected
and stacked on sheet ejection tray 19 located at an upper portion
outside the apparatus.
[0061] Through the second conveyance path 200, sheet S is ejected
and stacked on sheet ejection tray 40 by paired ejection rollers
20.
[0062] On the third conveyance path 300, there are provided stacker
51 that stocks temporarily sheet S and ejection device 60 that
pushes up plural sheets stacked on the stacker 51 to eject them
from the stacker 51.
[0063] The ejection device 60 has therein ejection claw 57 that
pushes up plural sheets and ejection belt 56 representing a moving
device that moves the ejection claw 57 in the direction to push up
the ejection claw 57 along the stacker 51.
[0064] A bundle of sheets subjected to stapling processing by
stapler 50 after prescribed number of sheets S are stacked on
stacker 51, or a bundle of plural sheets collected on the stacker
51 is pushed up by ejection device 60 to be ejected and stacked on
sheet ejection tray 40 by paired ejection rollers 20.
[0065] Incidentally, the ejection device 60 has a plurality of
ejection belts 56, depending on a size of a sheet to be used.
[0066] For example, when carrying out post-processing for sheets
ranging from B5 to A3 in terms of a size, one ejection belt 56 is
provided near each of both ends of a B5 sheet size, for
post-processing of B5 and A4 sheet, by which B5 and A4 sheets are
pushed up. One ejection belt 56 is provided near each of both ends
of a B4 sheet size, for post-processing of B4 and A3 sheet, by
which B4 and A3 sheets are pushed up.
[0067] Controller C2 controls the aforesaid operations relating to
post-processing apparatus B, in accordance with information of
operations of post-processing received through communication device
C21.
[0068] Each of FIGS. 3 (a) and 3 (b) is a schematic diagram showing
a sheet conveyance course through the first conveyance path and a
sheet conveyance course through the second conveyance path.
[0069] FIG. 3 (a) shows a conveyance course (one-dot chain lines)
for sheet S through the first conveyance path 100, and FIG. 3 (b)
shows a conveyance course (one-dot chain lines) for sheet S through
the second conveyance path 200.
(1) First Conveyance Path 100 (Printer Mode, Sheet Ejection with an
Image Surface Facing Downward)
[0070] In FIG. 3 (a), sheet S ejected from image forming apparatus
A with an image surface facing upward (face-up) is conveyed by
paired entrance rollers 11, then, passes through passage 121
located at a lower part of upper first switching gate G1, to be
interposed between paired conveyance rollers 12, and passes through
passage 123 located at an upper part of second switching gate G2
that is positioned downward obliquely.
[0071] Then, the sheet S passes through paired conveyance rollers
14, passage 15 and paired conveyance rollers 16 to stop once.
[0072] Then, after stopping once, the sheet S is given an operation
of a switchback by paired conveyance rollers 12, 14 and 16 which
rotate reversely, and passes through passage 122 positioned at an
upper part of the first switching gate G1 and passage 17 located
higher (first conveyance path 100), and is ejected out by paired
ejection rollers 18 onto sheet ejection tray 19 positioned at an
upper part outside the apparatus with its image surface facing
downward (face-down), to be placed in the order of pages.
(2) Second Conveyance Path 200 (Copy Mode, Sheet Ejection with an
Image Surface Facing Upward, Non-Staple Mode Including Offset
Ejection)
[0073] In FIG. 3 (b), sheet S ejected from image forming apparatus
A with an image surface facing upward is conveyed by paired
entrance rollers 11, then, passes through passage 121 located at a
lower part of upper first switching gate G1.
[0074] Then, the sheet S is interposed between paired conveyance
rollers 12, and passes through passage 123 located at an upper part
of second switching gate G2 that is positioned downward obliquely,
and is ejected out with its image surface facing upward to be
placed in the order of pages by paired ejection rollers 20 onto
sheet ejection tray 40 that is located outside the apparatus.
[0075] FIG. 4 is a schematic diagram showing a sheet conveyance
course through the third conveyance path.
[0076] FIG. 4 shows a conveyance course (one-dot chain lines) for
sheet S through the third conveyance path 300.
(3) Third Conveyance Path 300 (Copy Mode, Sheet Ejection with an
Image Surface Facing Upward, Staple Mode)
[0077] In FIG. 4, sheets S which have been subjected to image
forming processing in image forming apparatus A are ejected out in
succession with an image surface facing upward, beginning with a
copy of the last page.
[0078] Sheet S fed into sheet post-processing apparatus B is
conveyed by paired entrance rollers 11, and passes through passage
121 located at a lower part of upper first switching gate G1.
[0079] Then, the sheet S is interposed between paired conveyance
rollers 12, and passes through passage 124 located at an upper part
of third switching gate G3 that is positioned downward obliquely,
or through lower passage 125, and is fed in stacker 51 through
paired conveyance rollers 41, passage 42 (third conveyance path
300) and paired conveyance rollers 43 positioned at the downstream
side of the passage 42.
[0080] Sheet S interposed between and conveyed by the paired
conveyance rollers 43 positioned at the downstream side of the
passage 42 is discharged to an upper space of stacker 51 arranged
obliquely, and slides and rises further while touching stacker 51
or an upper face of a sheet stacked on the stacker 51.
[0081] After sliding and rising, the sheet S starts descending with
its own weight, and slides down along an inclined plane of stacker
51 to stop after hitting sheet hitting surface (stopper member) 52
near stapler 50.
[0082] Rotary blade wheel 44 that assists the sheet S for sliding
down has blades (having no symbol), whereby, when the sheet S is
subject to a switchback, rotating blades are brought into sliding
contact with the sheet S, so that the sheet S is caused to touch
the stopper member 52 surely.
[0083] The numeral 53 represents a pair of alignment members
provided movably on both sides of the aforesaid stacker 51.
[0084] The paired alignment members 53 are movable in the direction
perpendicular to the sheet-conveyance direction.
[0085] When sheet S is discharged onto stacker 51, the paired
alignment members 53 are opened to be broader than a sheet width
and when the sheet S slides down along stacker 51 and hits stopper
member 52 to stop, the paired alignment members 53 move in the
direction of the sheet width on a reciprocation basis, and conduct
width aligning (alignment) of a bundle of sheets by tapping a side
edge of sheets S.
[0086] After sheets S in prescribed quantity are stacked and
aligned on stacker 51 at this stopping position, binding processing
(staple processing) is conducted by stapler 50 and bundle of
stapled sheets S1 is completed.
[0087] Even when the staple processing is not conducted, it is also
possible to employ constitution wherein plural sheets S are
conveyed to stacker 51 for improving accuracy of alignment and,
width aligning (alignment) of bundle of sheets S2 stacked simply is
conducted by alignment member 53.
[0088] On a part in the width direction of a sheet-stacking surface
of stacker 51, there is formed a notched portion extending in the
direction perpendicular to the width direction, and in this notched
portion, there are arranged plural ejection belts 56 each being
wound around driving pulley 54 and driven pulley 55, so that the
plural ejection belts may be driven to rotate.
[0089] On a part of the ejection belt 56, there is fixed ejection
claw 57, and a tip portion of the ejection claw 57 moves to draw an
oblong locus as shown with illustrated one-dot chain lines.
[0090] Bundle of stapled sheets S1 or bundle of plural sheets S2
simply stacked which is placed on the ejection belt 56 slides, with
its trailing edge held by ejection claw 57 of ejection belt 56,
along a placement surface of stacker 51, to be pushed upward
obliquely, and advances to the position of a nip of paired ejection
rollers 20.
[0091] Bundle of stapled sheets S1 or bundle of plural sheets S2
simply stacked is interposed between rotating paired ejection
rollers 20, to be ejected and stacked onto sheet ejection tray
40.
[0092] Each of FIGS. 5 (a) and 5 (b) is a detailed diagram of the
ejection claw fixed on the ejection belt.
[0093] Each of FIGS. 5 (a) and 5 (b) is a sectional view of
ejection claw 57 that is viewed in the same direction as in FIG.
4.
[0094] FIG. 5 (a) is a detailed diagram of ejection claw 57 and
FIG. 5 (b) is a detailed diagram of a protrusion of the ejection
claw 57.
[0095] The ejection claw 57 and its protrusions will be described
as follows, referring to FIG. 5 (a) and FIG. 5 (b).
[0096] The ejection claw 57 is moved by ejection belt 56 in the
direction of arrow E, when bundle of stapled sheets S1 or bundle of
plural sheets S2 simply stacked (hereafter, bundle of stapled
sheets S1 or bundle of plural sheets S2 simply stacked is described
simply as a bundle of sheets) is ejected.
[0097] The ejection claw 57 has therein main body section 58 fixed
on ejection belt 56 which is the aforesaid moving device, and sheet
contact section 59 that is fixed on the main body section 58 with
an adhesive or the like and is in contact with by sheets when
bundle of sheets S1 or bundle of sheets S2 is pushed up.
[0098] The main body section 58 is formed with a resin which is
used usually in a post-processing apparatus, and it is fixed on the
ejection belt 56 with screws or an adhesive.
[0099] Sheet contact section 59 has, on its sheet contact surface
591, plural protrusions 592 which protrude toward bundle of sheets
S1 or bundle of sheets S2.
[0100] The protrusions 592 extend in the direction that is parallel
to the width direction (the width direction means a direction
perpendicular to the sheet-conveyance direction, that is, the
illustration sheet front-back direction) of a sheet of a bundle of
sheets and protrude toward the bundle of sheets, and for example,
they are projections in a rectangular form.
[0101] It is preferable that width w1 of the aforesaid projection
in a rectangular form (namely, protrusion 592) is about 1 mm, and
height h1 is about 0.3 mm.
[0102] When the width of the projection is broad, the number of
projections is fewer, resulting in fewer portions where sheets are
caught. When the width of the projection is narrow, strength of
protrusion 592 is lowered.
[0103] When the height of the projection is low, a sheet is hardly
caught, while, when the projection is tall, accuracy of alignment
in the conveyance direction is deteriorated, and a sheet is more
easily hurt at the corner of the protrusion.
[0104] Further, it is preferable that width w2 of recess 595
between adjoining protrusions is about 2 mm, and when the width is
broad, the number of projections is fewer, resulting in fewer
portions where sheets are caught. When the width of the projection
is narrow, a sheet is hardly caught.
[0105] At least surface 593 facing ejection belt 56 among both side
faces of the aforesaid rectangular-shaped projection (namely,
protrusion 592) is at prescribed angle .theta. on the bottom plane
of recess 595 between adjoining protrusions 592.
[0106] It is desirable that the prescribed angle .theta. is an
angle so that the sheet S constituting a bundle of sheets is caught
in each protrusion 592, and so that a sheet does not get over each
of protrusions 592, which is for example, 80.degree.-95.degree.,
preferably 90.degree..
[0107] When the prescribed angle .theta. is greater than
95.degree., a sheet is hardly caught by the protrusion 592, and a
sheet easily gets over the aforesaid plural protrusions to be
shifted toward tip portion 571 of ejection claw 57.
[0108] Further, when the prescribed angle .theta. is smaller than
80.degree., a sheet tends to cut into the root 592a of protrusion
592, and scratches or the like tend to be caused on a contacting
portion on the sheet when a bundle of sheets is ejected.
[0109] A length of the protrusion 592 is extended across the total
length in the width direction of ejection claw 57.
[0110] The protrusion 592 may be divided in the form of broken
lines.
[0111] A protrusion located at the uppermost position of the
ejection claw 57 among plural protrusions arranged on sheet contact
section 59 is taller than other protrusions.
[0112] In other words, protrusion 594 that is taller than
protrusion 592 is provided on the tip portion 571 side.
[0113] The protrusion 594 prevents a bundle of sheets or sheets
constituting a bundle of sheets from being protruded from ejection
claw 57.
[0114] Therefore, it is preferable that height h2 of the protrusion
594 is about 0.4 mm, for example, which is higher than height h1 of
protrusion 592.
[0115] Protrusion 594 has an angle of about 120.degree. to the
bottom plane of recess 595 to prevent protrusion 594 from kicking a
trailing edge of a bundle of sheets and from causing damage even
when a bundle of sheets is drawn out by paired ejection rollers
20.
[0116] In this case, protrusion 594 prevents sheets constituting a
bundle of sheets from being protruded from ejection claw 57,
because a bundle of sheets is caught mechanically by the protrusion
594.
[0117] With respect to sheet contact section 59, it is made of a
material having a great friction coefficient, such as, for example,
rubber, so that a friction may prevent a bundle of sheets from
slipping on sheet contact surface 591 of the sheet contact section
59, in addition to mechanical catching of a bundle of sheets by the
aforesaid protrusion 592.
[0118] It is also possible to replace only sheet contact section 59
in accordance with a structure of the apparatus, by separating
ejection claw 57 into main body section 58 and sheet contact
section 59.
[0119] Each of FIGS. 6 (a) and 6 (b) is a diagram of another
embodiment for the protrusion provided on an ejection claw.
[0120] FIG. 6 (a) shows a second embodiment of the protrusion, and
FIG. 6 (b) shows a third embodiment of the protrusion.
[0121] In FIG. 6 (a), opposite side 598 of surface 593 facing
ejection belt 56 of protrusion 596 is cut off obliquely.
[0122] Other shapes and dimensions are the same as those of
protrusion 592.
[0123] By doing this, an angle of the opposite side 598 of surface
593 facing ejection belt 56 can be an obtuse angle that is greater
than 90.degree., which can lighten damage on a portion of the sheet
touching sheet contact surface 591.
[0124] In FIG. 6 (b), opposite side 599 of surface 593 facing
ejection belt 56 of protrusion 597 is cut off to be in the form of
a circular arc.
[0125] Other shapes and dimensions are the same as those of
protrusion 592.
[0126] By doing this, an angle of the opposite side 599 of surface
593 facing ejection belt 56 can be a circular arc, which can
lighten damage on a portion of the sheet touching sheet contact
surface 591.
[0127] FIG. 7 is a diagram of the fourth embodiment for a
protrusion provided on the ejection claw.
[0128] Sheet contact surface 591 of sheet contact section 59 is
rough surface 600, except protrusion 594 of tip portion 571.
[0129] The rough surface 600 is a finely irregular surface like the
form of sandpaper.
[0130] Since a sheet is caught by protrusions that form rough
surface 600, the sheet is restrained from being shifted on rough
surface 600 of ejection claw 57A toward tip portion 571, thus,
conveyance abnormality for the sheet can be prevented.
[0131] It is preferable that the surface roughness of rough surface
600 is about #80-#180 (Japan Industrial Standards). If the surface
is finer than that, a sheet is hardly caught, resulting in
difficult control of conveyance abnormality.
[0132] If the surface is rougher than that, a contact portion of a
sheet that comes in contact with sheet contact surface 591 is
damaged.
[0133] Though there has been described an occasion where main body
section 58 and sheet contact section 59, representing different
members from each other, are separated from each other with respect
to ejection claw 57, the main body section 58 and the sheet contact
section 59 may also be formed unitedly.
[0134] In the case of an ejection claw (not shown) wherein main
body section 58 and sheet contact section 59 are formed unitedly,
plural protrusions being the same as protrusions 592 are provided
on a sheet contact surface where a bundle of sheets comes in
contact.
[0135] Meanwhile, plural protrusions being the same as protrusions
592 restrain a sheet from being shifted on the surface of the
ejection claw toward tip portion 571. Therefore, the ejection claw
does not always need to be constituted with a material having a
high friction coefficient such as a rubber, and it may be
constituted with ordinary resin used in a post-processing
apparatus.
[0136] Owing to this, the number of parts can be reduced, and the
number of types of materials to be used can be reduced, resulting
in simplification of a manufacturing process and a reduction of
manufacturing costs.
[0137] By arranging plural ejection claws which push up and eject
plural sheets stacked on a stacker that stocks sheets temporarily
at positions corresponding to sizes of sheets to be used, and by
providing plural protrusions which protrude toward a sheet, on a
sheet contact surface of an ejection claw where a sheet comes in
contact, it is possible to provide a highly productive
post-processing apparatus wherein no conveyance abnormality is
caused when ejecting plural sheets in a stacker from the stacker,
independently of sheet sizes, and the reliability is improved,
then, a production shut-down caused by an interruption with
abnormality is lightened, and to provide an image forming system
having therein the aforesaid post-processing apparatus.
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