U.S. patent application number 11/614164 was filed with the patent office on 2007-06-21 for sheet post-processing apparatus.
This patent application is currently assigned to TOSHIBA TEC KABUSHIKI KAISHA. Invention is credited to Tomomi Iijima, Hiroyuki Taki, Yasunobu Terao, Mikio Yamamoto.
Application Number | 20070138731 11/614164 |
Document ID | / |
Family ID | 38172554 |
Filed Date | 2007-06-21 |
United States Patent
Application |
20070138731 |
Kind Code |
A1 |
Terao; Yasunobu ; et
al. |
June 21, 2007 |
SHEET POST-PROCESSING APPARATUS
Abstract
A sheet post-processing apparatus comprises a pair of alignment
plates for aligning the plurality of sheets conveyed from an image
forming apparatus at the two lateral sides, the pair of alignment
plates being movable by a predetermined distance in a direction
perpendicular to the direction of conveyance of the sheets, and a
stapler also movable along the leading edge of the aligned
plurality of sheets. The stapler moves according to the alignment
position of the sheets and staples the sheets at a plurality of
positions corresponding to the alignment position. As the stapled
bundles of sheets are sequentially discharged, they are stacked on
a delivery tray in a zigzag manner.
Inventors: |
Terao; Yasunobu;
(Shinagawa-ku, Tokyo, JP) ; Yamamoto; Mikio;
(Shinagawa-ku, Tokyo, JP) ; Iijima; Tomomi;
(Shinagawa-ku, Tokyo, JP) ; Taki; Hiroyuki;
(Shinagawa-ku, Tokyo, JP) |
Correspondence
Address: |
AMIN, TUROCY & CALVIN, LLP
1900 EAST 9TH STREET, NATIONAL CITY CENTER
24TH FLOOR,
CLEVELAND
OH
44114
US
|
Assignee: |
TOSHIBA TEC KABUSHIKI
KAISHA
2-17-2, Higashigotanda
Tokyo
JP
141-8664
|
Family ID: |
38172554 |
Appl. No.: |
11/614164 |
Filed: |
December 21, 2006 |
Current U.S.
Class: |
270/58.12 |
Current CPC
Class: |
B65H 37/04 20130101;
G03G 2215/00827 20130101; B42C 1/125 20130101; G03G 15/6544
20130101; B65H 2801/09 20130101 |
Class at
Publication: |
270/058.12 |
International
Class: |
B65H 33/04 20060101
B65H033/04 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2005 |
JP |
2005-368278 |
Claims
1. A sheet post-processing apparatus for aligning a plurality of
sheets conveyed from an image forming apparatus and stapling and
delivering them, said apparatus comprising: a processing tray
capable of carrying a plurality of sheets conveyed from the image
forming apparatus; alignment means including a pair of alignment
plates for aligning the plurality of sheets carried by the
processing tray at the two lateral sides running in the direction
of conveyance of the plurality of sheets, the pair of alignment
plates being movable between a first alignment position and a
second alignment position displaced from the first alignment
position by a predetermined distance in a direction perpendicular
to the direction of conveyance; and staple means including a
stapler movable along the leading edge of the plurality of sheets
aligned by the alignment means in the direction of conveyance and
adapted to move the stapler according to the change of alignment
position in order to staple the conveyed sheets at a plurality of
positions; the sheets stapled at the first alignment position and
those stapled at the second alignment position being sequentially
discharged and led to a delivery tray so as to shift the staple
positions of the bundles of sheets stacked on the delivery tray in
a zigzag manner.
2. The apparatus according to claim 1, wherein the staple positions
and the gap separating the staples are held same among the bundles
of sheets when the bundles of sheets stapled by the staple means
have the same size.
3. The apparatus according to claim 2, wherein, when the gap
separating the staples of each bundle of sheets stapled by the
staple means is L1, the positional shift L2 of an upper bundle of
sheets stacked on the delivery tray from a lower bundle of sheets
stacked on the delivery tray is defined by L2<L1/2.
4. A sheet post-processing apparatus for aligning a plurality of
sheets conveyed from an image forming apparatus and stapling and
delivering them, said apparatus comprising: a processing tray
capable of carrying a plurality of sheets conveyed from the image
forming apparatus; alignment means including a pair of alignment
plates for aligning the plurality of sheets carried by the
processing tray at the two lateral sides running in the direction
of conveyance of the plurality of sheets, the pair of alignment
plates being capable of reciprocating between a first alignment
position and a second alignment position displaced from the first
alignment position by a predetermined distance in a direction
perpendicular to the direction of conveyance; a stapler movable
along the leading edge of the plurality of sheets aligned by the
alignment means in the conveyance direction; a control section for
controlling the staple so as to cyclically move it along the staple
positions according to the change of alignment position of the
alignment means, the control section moving the stapler in the
first direction when the alignment means is at the first alignment
position and causing it to staple the sheets at a plurality of
positions along the moving route, the control section moving the
stapler in the direction opposite to the first direction when the
alignment means is at the second alignment position and causing it
to staple the sheets at a plurality of positions along the moving
route; and a delivery section for leading the sheets stapled at the
first alignment position and those stapled at the second alignment
position to a delivery tray; the staple positions of the bundles of
sheets stacked on the delivery tray being shifted in a zigzag
manner.
5. The apparatus according to claim 4, wherein the control means
controls the position of the staple according to the alignment
position in such a way that it moves the stapler in the first
direction at the first alignment position and operates the stapler
to staple the sheets at a first position and at a second position
located along the moving direction but it moves the stapler to a
third position separated from the second position by a
predetermined distance in the first direction when the alignment
means is driven to move to the second alignment position and it
moves the stapler in the direction opposite to the first direction
at the second alignment position and operates the stapler to staple
the sheets at a third position and at fourth position located along
the moving direction, while it moves the stapler to the first
position separated from the fourth position by a predetermined
distance when the alignment means is driven to return to the first
alignment position.
6. The apparatus according to claim 4, wherein when the gap
separating the staples of each bundle of sheets stapled by the
staple means at the first and second alignment positions is L1, the
predetermined distance L2 by which the stapler is moved according
to the move of alignment position of the alignment means is defined
by L2<L1/2.
7. The apparatus according to claim 4, wherein the alignment means
includes a second alignment means for aligning the plurality of
sheets at the leading edge thereof in the direction of conveyance
in addition to the pair of alignment plates for aligning the
plurality of sheets carried by the processing tray from the two
lateral sides running in the direction of conveyance of the
plurality of sheets.
8. The apparatus according to claim 4, wherein the second alignment
means is arranged at the stapler and includes a stopper for
receiving the leading edge of the sheets in the direction of
conveyance.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims the benefit of
priority from the prior Japanese Patent Application No.
2005-368278, filed on December 21, the entire contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to a sheet post-processing apparatus
for performing a post-processing operation on the sheets of paper
delivered from an image forming apparatus such as a copying
machine, a printer or a composite machine.
[0004] 2. Description of the Related Art
[0005] Some image forming apparatuses that have been marketed in
recent years are accompanied by a sheet post-processing apparatus
for sorting the sheets carrying an image produced as a result of an
image forming operation thereon and/or executing one or more than
one post-processing processes such as stapling sheets. Such a
post-processing apparatus is normally arranged downstream relative
to the delivery section of the image forming apparatus main
body.
[0006] A sheet post-processing apparatus for stapling sheets is
typically adapted to align a plurality of sheets (a bundle of
sheets) by means of an aligning means, staple them, and deliver
them onto a delivery tray, where stapled bundles of sheets are laid
one on the other.
[0007] In such a post-processing apparatus, a succeeding sheet is
subjected to a post-processing process only after the completion of
the post-processing process of the immediately preceding sheet.
Additionally, the post-processing apparatus may or may not be
provided with a stand-by tray arranged on the way down to the
stapler for the purpose of holding the sheets of paper delivered
from the image forming apparatus on a stand-by status.
[0008] Japanese Patent No. 2879969 describes a structure to be used
for a stapling process. The structure of the above-cited Patent
Document includes a binding means for binding the sheets of
recording paper delivered from an image forming apparatus, a moving
means for moving the binding means along a plurality of binding
positions for binding sheets of recording paper and a position
control means for controlling the position of the moving means so
as to align the final binding position of the current sheets of
recording paper with the starting binding position of the next
sheets of recording paper.
[0009] While the structure of the above-cited Patent Document can
reduce the moving distance and the moving time of the binding
means, the number of the stapled sheets to be laid at a delivery
tray needs to be limited because the bundles of stapled sheets of
recording paper are delivery at the same binding positions and,
when bundles of stapled sheets of recording paper are delivered and
laid one on the other at the delivery tray, the bundles are heaped
up higher at the part of the binding positions than at the
remaining part of the sheets. Additionally, the above-described
structure is accompanied by a drawback that a succeeding bundle of
sheets that is stapled and delivered to the delivery tray forces
out one or more than one uppermost bundle of sheets already
delivered to the delivery tray.
[0010] Jpn. Pat. Appln. Laid-Open Publication No. 2000-177921
describes a post-processing apparatus. In the apparatus described
in the above-cited Patent Document, a pair of aligning members is
arranged in a direction perpendicular to the conveyance direction
of conveying sheets with a predetermined gap separating them and
adapted to align sheets of a bundle. The alignment position for
aligning sheets for bundles by means of the aligning members is
shifted from bundle to bundle before the bundles of aligned sheets
are delivered to a stack tray.
[0011] Thus, the post-processing apparatus of the above-cited
Patent Document is designed to shift bundles of sheets from bundle
to bundle instead of moving the stack tray in a direction
perpendicular to the conveyance direction of conveying sheets of
paper.
[0012] Jpn. Pat. Appln. Laid-Open Publication No. 2001-220055
described a sheet processing apparatus. In the apparatus described
in this patent document, a pair of aligning members (side stoppers)
is arranged in a direction perpendicular to the conveyance
direction of conveying sheets with a predetermined gap separating
them and adapted to align sheets of a bundle.
[0013] For binding a bundle of sheets at two positions by means of
the sheet processing apparatus, the stapler is moved to the second
stapling position after binding the bundle of sheets at the first
stapling position. When the stapler is moved toward the second
position, the side stoppers are moved in the direction opposite to
the moving direction of the stapler so as to reduce the moving
distance of the stapler.
[0014] However, with either of the apparatus described in Jpn. Pat.
Appln. Laid-Open Publication No. 2000-177921 and Jpn. Pat. Appln.
Laid-Open Publication No. 2001-220055, the stapled positions of
some of the bundles of sheets can be aligned to heap up the bundles
higher at the part of the binding positions than at the remaining
part of the sheets. Additionally, a succeeding bundle of sheets
that is stapled and delivered to the stack tray can force out one
or more than one uppermost bundle of sheets already stored on the
stack tray.
[0015] Therefore, the present invention provides a sheet
post-processing apparatus that can reduce the risk of collapsing
the heap of bundles of sheets of paper on a delivery tray by
shifting the bound positions of an upper bundle of sheets from
those of a lower bundle of sheets when delivering those bundles to
the delivery tray and lay them one on the other after a stapling
process.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic perspective view of an embodiment of
sheet post-processing apparatus according to the present
invention;
[0017] FIG. 2 is a schematic plan view of the sheet post-processing
apparatus of FIG. 1;
[0018] FIG. 3 is a schematic illustration of the configuration of a
sheet post-processing apparatus according to the present
invention;
[0019] FIG. 4 is a schematic perspective view of the stapler of a
sheet post-processing apparatus according to the invention;
[0020] FIG. 5 is a schematic perspective view of the longitudinal
alignment roller of a sheet post-processing apparatus according to
the invention;
[0021] FIG. 6 is a schematic illustration of the paddle of a sheet
post-processing apparatus according to the invention;
[0022] FIG. 7 is a schematic perspective view of the stand-by tray
and the processing tray of a sheet post-processing apparatus
according to the invention;
[0023] FIG. 8 is a schematic plan view of the stand-by tray and the
processing tray of a sheet post-processing apparatus according to
the invention;
[0024] FIG. 9 is a schematic perspective view of the transversal
alignment plate and the conveyor belt of a sheet post-processing
apparatus according to the invention;
[0025] FIG. 10 is a schematic illustration of the delivery
operation of delivering sheets from a processing tray of a sheet
post-processing apparatus according to the present invention;
[0026] FIG. 11 is a schematic illustration of the movement of the
stand-by tray of a sheet post-processing apparatus according to the
present invention;
[0027] FIG. 12 is a schematic illustration of the stapling
operation of an ordinary sheet post-processing apparatus;
[0028] FIG. 13 is a schematic illustration of the basic operation
of the stapler of a sheet post-processing apparatus according to
the present invention;
[0029] FIG. 14A and FIG. 14B are schematic illustrations of the
operation of the stapler of a sheet post-processing apparatus
according to the present invention; and
[0030] FIG. 15A, FIG. 15B and FIG. 15C are schematic illustrations
of the operation of delivering the sheets that have been stapled by
a sheet post-processing apparatus according to the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] Throughout this description, the embodiments and examples
shown should be considered as exemplars, rather than limitations on
the apparatus of the present invention.
[0032] Now, a preferred embodiment of the present invention will be
described in detail by referring to the accompanying drawings.
Throughout the drawings, the same parts are denoted by the same
reference symbols and will not be described repeatedly.
[0033] FIG. 1 is a schematic perspective view of an embodiment of
sheet post-processing apparatus according to the present invention.
FIG. 2 is a schematic plan view of the apparatus of FIG. 1. FIG. 3
is a schematic illustration of the configuration of a sheet
post-processing apparatus according to the present invention. FIGS.
4 through 11 schematically illustrate different parts of a sheet
post-processing apparatus according to the present invention.
[0034] The configuration and the operation of each part shown in
FIGS. 1 and 2 will be described below by referring to FIG. 4 and
the subsequent drawings. Firstly, processing for a sheet by a sheet
post-processing apparatus according to the invention will be
described mainly by referring to FIG. 3.
[0035] As shown in FIG. 3, sheet P on which an image is formed by
an image forming apparatus 5 such as a copying machine is
discharged from a pair of delivery rollers 6 and conveyed to the
sheet post-processing apparatus 7. The sheet post-processing
apparatus 7 includes a stand-by tray 10, a processing tray 12, a
stapler 14, a first delivery tray 16, a second delivery tray 18, a
gate G and so on.
[0036] The sheet P discharged from the pair of delivery rollers 6
of the image forming apparatus 5 is received by an entrance roller
pair 22 arranged near the sending-in entrance of the sheet
post-processing apparatus 7. The entrance roller pair 22 includes
an upper roller 22a and a lower roller 22b. The entrance roller
pair 22 is driven by a motor 26 (FIG. 1).
[0037] A gate G is arranged at the downstream side of the entrance
roller pair 22. The gate G sorts the sheets P received by the
entrance rollers 22 into two paths (flows) The gate G shows a
wedge-shaped cross section and the narrow end of the wedge is
directed to the entrance rollers 22. The gate G is rotatably
supported by a lateral wall section in the sheet post-processing
apparatus 7. The gate G is adapted to selectively take a first
position where the narrow end thereof is directed to the upper
entrance roller 22a or a second position where the narrow end
thereof is directed to the lower entrance roller 22b.
[0038] The first position is to be used to select the path for
sheets P that require post-processing, whereas the second position
is to be used to select the path for sheets P that does not require
any post-processing.
[0039] When the gate G is at the first position, each sheet P is
supplied to the first sheet feeding roller pair 24 and then from
the first sheet feeding roller pair 24 to the stand-by tray 10. A
paper path ceiling 36 (FIG. 1) is arranged between the entrance
rollers 22 to the stand-by tray 10 to guide the sheet P to a first
sheet feeding roller pair 24. The first sheet feeding roller pair
24 includes an upper roller 24a and a lower roller 24b.
[0040] The stand-by tray 10 receives a plurality of sheets P and
lays them one on the other there until the ongoing processing at
the processing tray 12 ends. The processing tray 12 aligns and
supports the laid sheets P until the end of the ongoing stapling
process at the stapler 14, which is a processing mechanism for
post-processing.
[0041] As a predetermined number of sheets are stacked in the
stand-by tray 10, the tray members 10a, 10b are opened by a motor
34 (FIG. 1) in respective directions indicated by arrows n and m in
FIG. 7. Then, as a result, the sheets P drop into the processing
tray 12 by their own weights and fed to the stapler 14.
[0042] As shown in FIG. 4, the stapler 14 is driven to slide in the
directions indicated by arrows u by a staple drive section 49 so as
to be positioned for a stapling process. While only a single
stapler 14 is provided, FIG. 4 shows the stapler before it is
driven to slide and after it has been driven.
[0043] The processing tray 12 has a pair of longitudinal alignment
rollers 38a, 38b as shown in FIGS. 5 and 6.
[0044] The upper and lower longitudinal alignment rollers 38a, 38b
are also used to pinch the stapledbundleof sheets T between them
and take it out from the stapler 14 after the stapling process. The
longitudinal alignment roller 38a is driven by motor 40, whereas
the longitudinal alignment roller 38b is driven by motor 42.
[0045] For the sheets P that falls so as to be supplied to the
processing tray 12, a rotatable paddle 44 is arranged at the
position where the rear ends of the sheets P are placed. The paddle
44 is adapted to longitudinally align the uppermost sheet P of the
sheets that are laid on the processing tray 12.
[0046] As shown in FIG. 6, the paddle 44 includes a receiving
section 44a for receiving the sheets P that enter the stand-by tray
10, a slapping section 44b for slapping down the sheets P on the
processing tray 12 and a feed section 44c for aligning the sheets P
on the processing tray 12 and is driven by a paddle motor 46 (FIG.
5). The paddle 44 is made of rubber and hence is elastic.
[0047] A stopper 45 is arranged at the end of the processing tray
12 located at the side of the stapler 14 so as to contact the rear
ends of the sheets P and regulate the positions of the rear ends. A
conveyor belt 50 is arranged substantially at the center of the
processing tray 12. The conveyor belt 50 is adapted to convey the
bundle of sheets T that has been subjected to a stapling process
and taken out from the stapler 14 by the longitudinal alignment
rollers 38a, 38b to either the first delivery tray 16 or the second
delivery tray 18. A feed claw 50a for hooking the rear end of the
bundle of sheets T is fitted to the conveyor belt 50.
[0048] While the stand-by tray 10 can fall and supply sheets P to
the processing tray 12, it can also be used to convey sheets P
either toward the first delivery tray 16 or toward the second
delivery tray 18. More specifically, when sheets P are conveyed
toward the delivery tray 16 or toward the delivery tray 18, the
rotary roller pair 28 for aligning sheets P is brought into contact
with the sheets P laid on the stand-by tray 10. The rotary roller
pair 28 is controlled for its vertical movement by a drive source
30 and driven to rotate by a motor 32 (FIG. 2).
[0049] As shown in FIG. 3, the stand-by tray 10 is so arranged as
to show an angle of inclination .theta.1 so as to support sheets P
in a condition where the front ends of the sheets P are found above
the respective rear ends thereof. The first delivery tray 16 or the
second delivery tray 18 is selected and driven to move up and down
by a drive section 52.
[0050] Thus, when receiving sheets P, the first delivery tray 16 or
the second delivery tray 18 that is selected is raised or lowered
substantially to the height of the processing tray 12 to align the
sheets P discharged onto it better. The first delivery tray 16 or
the second delivery tray 18 that is selected is so arranged as to
show an angle of inclination .theta.2 so as to support sheets P in
a condition where the front ends of the sheets P are found above
the respective rear ends thereof.
[0051] As shown in FIGS. 7 and 8, the stand-by tray 10 is provided
with a pair of tray members 10a, 10b that are formed to project
from the wall surface thereof and adapted to slide sideways to
receive sheets P and support them at the corresponding opposite
ends thereof. The tray members 10a, 10b are provided respectively
with stoppers 10c, 10d for regulating the rear ends of the received
sheets P.
[0052] The stand-by tray 10 is driven to slide by a motor 34 (FIG.
2). A pair of transversal alignment plates 47a, 47b is arranged
between the stand-by tray 10 and the processing tray 12 as shown in
FIG. 9 in order to prevent the sheets P fallen from the stand-by
tray 10 and supplied to the processing tray 12 from being
disordered in the transversal direction that is orthogonal to the
sheet conveying direction and transversally align them. The
transversal alignment plates 47a, 47b can be driven to slide in the
directions indicated by arrow v so as to make the gap between them
match the width of the sheets P. In other words, their alignment
positions can be shifted.
[0053] When the gate G is at the second position as shown in FIG.
3, a sheet P that does not require post-processing is fed to the
second sheet feeding roller pair 60 and then further to the third
sheet feeding roller pair 61. Each of the second sheet feeding
roller pair 60 and the third sheet feeding roller pair 61 includes
an upper sheet feeding roller and a lower sheet feeding roller. The
sheet P conveyed out from the third sheet feeding roller pair 61 is
sent to the fixed tray 19 arranged on the top surface of the sheet
post-processing apparatus 7.
[0054] The motors 26, 32, 34, 40, 42, 46 and 48 for driving the
above-described various mechanisms and the drive sections 49 and 52
are driven and controlled by a control circuit (not shown).
[0055] Now, the operation of the sheet post-processing apparatus 7
will be described in terms of the flow of sheets. As a sheet P on
which an image is formed by the image forming apparatus 5 is
supplied form the delivery roller pair 6, the sheet post-processing
apparatus 7 operates differently depending on (1) when the sheet P
is not to be subjected to post-processing, (2) when the sheet P is
to be subjected to post-processing and the post-processing of the
preceding sheet P has not been completed and (3) when the sheet P
is to be subjected to post-processing and the post-processing of
the preceding sheet P has been completed.
[0056] Firstly, (1) when the sheet P is not to be subjected to
post-processing, the narrowed part of the wedge-shaped gate G is
positioned to substantially point the lower entrance roller 22b.
The sheet P delivered from the entrance roller pair 22 is supplied
to the second sheet feeding roller pair 60 and then further to the
third sheet feeding roller pair 61. The sheet P that is fed out
from the third sheet feeding roller pair 61 is delivered to the
fixed tray 19 on the top surface of the sheet post-processing
apparatus.
[0057] Now, (2) when the sheet P is to be subjected to
post-processing (a stapling process) and there is no preceding
sheet P on the processing tray 12, the stand-by tray 10 is driven
to slide in the direction of arrow m or arrow n to either of the
positions indicated by dotted lines, where it drops the sheet P.
The transversal alignment plates 47a, 47b are arranged so as to
show a gap between them substantially equal to the width of the
sheet P in order to transversally align the dropping sheet P. Then,
as a result, the sheet P supplied by the sheet feeding roller pair
24 is directly dropped onto the processing tray 12 without being
obstructed by the stand-by tray 10 on the way.
[0058] When the sheet P is dropped, the longitudinal alignment
roller pair 38a is retreated upwardly and the receiving section 44a
of the paddle 44 receives the sheet P at the rear end of the sheet
P. The sheet P falls as its two lateral sides are guided by the
transversal alignment plates 47a, 47b so as to be aligned in the
transversal direction. Thereafter, the paddle 44 is driven to
rotate in the sense as indicated by arrow o in FIG. 6 in order to
drop the sheet P from its receiving section 44a from the rear end
of the sheet P and slaps it down onto the processing tray 12 by
means of its slapping section 44b.
[0059] Additionally, the paddle 44 sends out the sheet P in the
direction of arrow q by means of its feed section 44c until the
rear end of the sheet P contacts the stopper 45 to complete the
operation of longitudinally aligning the sheet P. Note that the
longitudinal alignment roller 38a may be driven to move up and down
each time a sheet P is delivered to it in order to perform the
operation of longitudinally aligning the sheet P on the processing
tray 12.
[0060] Thus, the sheet P on which an image is formed is directly
laid on the processing tray 12 from the sheet feeding roller pair
24 while it is sequentially aligned transversally and
longitudinally. As the number of sheets P on the processing tray 12
gets to a predetermined level, the sheets P on the processing tray
12 is stapled by the stapler 14 at one or more than one desired
positions to form a bundle of sheets T.
[0061] Thereafter, the bundle of sheets T is pinched by the
longitudinal alignment roller 38a that is driven to rotate in the
sense of arrow r and the longitudinal alignment roller 38b that is
driven to rotate in the sense of arrow s in FIG. 6 and conveyed
toward the first delivery tray 16.
[0062] As the rear end of the bundle of sheets T passes the
longitudinal alignment rollers 38a, 38b, it is hooked by the feed
claw 50a of the conveyor belt 50 that is driven to rotate in the
sense of arrow t in FIG. 5 and put on the first delivery tray 16.
At this time, the first delivery tray 16 is driven to slide from
the position indicated by a dotted line to the position indicated
by a solid line in FIG. 3.
[0063] Since the first delivery tray 16 is arranged with an angle
of inclination .theta.2 and hence the front ends of the sheets P
are found above the respective rear ends thereof, the preceding
sheet P delivered onto the first delivery tray 16 would not be
pushed out if the rear end of the preceding sheet P touches the
front end of the succeeding bundle of sheets T.
[0064] If the sheets of the preceding bundle of sheets T are
misaligned by the succeeding sheet P, the bundle of sheets T falls
by its own weight and hence is laid on the first delivery tray 16
with the rear ends of the sheets aligned with each other because of
the angle of inclination .theta.2. In other words, the delivered
sheets P are sequentially laid on the first delivery tray 16 in the
proper order to complete the process of stapling the sheets P.
[0065] Thus, sheets are sequentially laid on the first delivery
tray 16 in the above-described manner. As pointed out above, the
first delivery tray 16 is made to show an angle of inclination of
.theta.2 and hence the front ends of the sheets P on it are found
above the respective rear ends thereof. Therefore, if a sheet P is
curled to raise a middle part from the other parts thereof when
delivered onto the first delivery tray 16 and its front end touches
the preceding sheet P laid on the first delivery tray 16, the
preceding sheet P would not be pushed out by the succeeding curled
sheet P. In other words, the delivered sheets P are sequentially
laid on the first delivery tray 16 in the proper order.
[0066] Finally, the instance (3) when the sheet P is to be
subjected to post-processing and there are preceding sheets P
remaining on the processing tray 12 because the stapling process
that is being executed on them has been completed will be described
below.
[0067] In this condition, the tray members 10a, 10b are driven to
slide respectively from the positions indicated by dotted lines in
the directions opposite to arrows m and n to get to the positions
indicated by solid lines in FIG. 11 so that they can support sheets
P. Additionally, the rotary roller pair 28 is retreated above the
stand-by tray 10 so as not to obstruct the sheets P. Thus, the
sheet P discharged from the image forming apparatus 5 and delivered
by the sheet feeding roller pair 24 is temporarily laid on the
stand-by tray 10 until the processing tray 12 becomes ready for
receiving it.
[0068] The second and subsequent sheets P laid on the stand-by tray
10 fall onto the stand-by tray 10 and then are sent toward the
stoppers 10c, 10d by the rotary roller pair 28 that is driven to
rotate in the sense opposite to that of arrow f in FIG. 3 until the
rear ends of the sheets P contact the stoppers 10c, 10d so as to be
longitudinally aligned. Additionally, the stand-by tray 10 is
arranged to show an angle of inclination of .theta.1 so that the
front ends of the sheets P on the stand-by tray 10 are found above
the respective rear ends thereof. Thus, the sheets P are made to
contact the stoppers 10c, 10d by their own weights and hence
longitudinally aligned.
[0069] In this way, the supplied sheets P are sequentially laid on
the stand-by tray 10 in the proper order. If a preceding sheet P is
pushed by a succeeding sheet P and slightly misaligned, the
preceding sheet P falls to the position where its rear end contacts
the stoppers 10c, 10d because of the angle of inclination .theta.1.
Thus, the rear ends of the sheets P that are laid on the stand-by
tray 10 are held to an aligned state.
[0070] Meanwhile, as the preceding sheets P on the processing tray
12 are discharged toward the first delivery tray 16 and the
processing tray 12 is ready for receiving the succeeding sheets P,
the tray members 10a, 10b of the stand-by tray 10 are driven to
slide respectively in the direction of arrow m and the direction of
arrow n from their positions indicated by solid lines to the
positions indicated by dotted lines by way of the positions
indicated by dotted chain lines in FIG. 11.
[0071] Then, as the tray members 10a, 10b get to the respective
positions indicated by dotted chain lines in FIG. 11, the sheets P,
e.g., two sheets P, that are on a stand-by status on the stand-by
tray 10 are made to fall onto the processing tray 12 between the
tray members 10a, 10b. At this time, the gap separating the
transversal alignment plates 47a, 47b is made to be substantially
equal to the width of the sheets P. Thus, the sheets P that are
made to fall from the stand-by tray 10 are restricted at the
lateral sides thereof and transversally aligned by the transversal
alignment plates 47a, 47b.
[0072] The lower sheet P of the two sheets that are made to fall on
the processing tray 12 is sent in the direction of arrow q by the
longitudinal alignment roller 38b that is driven to rotate in the
sense opposite to that of arrow s in FIG. 6 so as to contact the
stopper 45 at the rear end of thereof to complete the operation of
aligning the sheet P in the longitudinal direction.
[0073] On the other hand, the upper sheet P of the two sheets that
are made to fall on the processing tray 12 is sent in the direction
of arrow q by the longitudinal alignment roller 38a that is driven
to rotate in the sense opposite to that of arrow r in FIG. 6 so as
to contact the stopper 45 at the rear end thereof to complete the
operation of aligning the sheet P in the longitudinal direction.
Thereafter, the longitudinal alignment roller 38a is retreated
upwardly.
[0074] Then, the third and subsequent sheets P discharged from the
image forming apparatus 5 are made to fall directly from between
the tray members 10a, 10b to the processing tray 12 without held to
a stand-by status on the stand-by tray 10. The third and subsequent
sheets P are sequentially aligned on the sheets P that have been
laid on the processing tray 12 by the paddle 44.
[0075] When the number of sheets P laid on the processing tray 12
gets to a predetermined level, a bundle of sheets T is formed by
the stapler 14 by way of a stapling process. Thereafter, the bundle
of sheets T is conveyed toward the first delivery tray 16 by the
longitudinal alignment rollers 38a, 38b and hooked by the feed claw
50a of the conveyor belt 50 at the rear end thereof so as to be put
on the first delivery tray 16 as shown in FIG. 10 to complete the
stapling process of the sheets P.
[0076] The overall operation of the sheet post-processing apparatus
7 is described above. Now, the configuration of the stapling
process section that characterized the present invention will be
described below.
[0077] Generally, sheets are stapled at a corner or at a plurality
of (e.g., two) positions along an edge of the sheets. When sheets
are stapled at a plurality of positions, bundles of sheets T are
stacked on the delivery tray 16 and the staples are laid one on the
other at staple positions ST to heap up as shown in FIG. 12. Then,
a succeeding bundle of sheets T that is stapled and delivered to
the delivery tray can force out one or more than one uppermost
bundle of sheets T already delivered to the tray 16 to collapse the
stack.
[0078] A sheet post-processing apparatus according to the invention
is characterized in that it can prevent staples from being laid one
on the other to form a heap. Then, it is possible to prevent the
stack of bundles of sheets on the stack tray from collapsing.
[0079] FIG. 13 is a schematic illustration of the basic operation
of the stapler 14 of a sheet post-processing apparatus according to
the present invention. As shown in FIG. 4, the stapler 14 can be
moved in the direction of u by the staple drive section 49.
Therefore, when sheets P are bound at a corner, the stapler is
moved to the position indicated by solid lines or dotted chain
lines in FIG. 13 for a stapling process. On the other hand, when
sheets P are bound at a plurality of (e.g., two) positions along an
edge of sheets P, the stapler is moved to the positions indicated
by dotted lines in FIG. 13 for a stapling process ST.
[0080] FIG. 14A and FIG. 14B are schematic illustrations of the
operation of the stapler of a sheet post-processing apparatus
according to the present invention when stapling sheets at two
positions along an edge of sheets P. They show how the stapler 14
and the transversal alignment plates 47a, 47b are moved.
[0081] FIG. 14A illustrates that sheets P are aligned at the first
alignment position by the transversal alignment plates 47a, 47b. In
this condition, the sheets P are aligned transversally at the two
lateral sides thereof in the direction along which the sheets P are
conveyed. The transversal alignment plates 47a, 47b are located at
respective positions indicated by b1 and b2.
[0082] Meanwhile, the stapler 14 is driven to slide along an edge
of the sheets P by the staple drive section 49 in the direction of
u and stops at the first staple position a1 for a stapling
operation of the stapling process. Then, the stapler 14 is further
driven to slide along the edge of the sheets P in the direction of
arrow A1 and stops at the second staple position a2 for another
stapling operation of the stapling process.
[0083] In this way, the stapler 14 is driven to move and stops at a
plurality of positions for the stapling process. As the stapling
process at the first and second staple positions ends, the sheets P
are conveyed toward the delivery tray 16 (or 18) by the conveyor
50. Note that the gap L1 separating the first staple position a1
and the second staple position a2 is about 120 mm.
[0084] As the stapled bundle of sheets is discharged, the
transversal alignment plates 47a, 47b are driven to move to a
slight extent in a direction perpendicular to the moving direction
of the sheets relative to the first alignment position as shown in
FIG. 14B. Then, the next bundle of sheets P that are brought in are
aligned in the transversal direction by the transversal alignment
plates 47a, 47b that have been moved at the second alignment
position. In this condition, the transversal alignment plates 47a,
47b are located at respective positions indicated by c1 and c2.
[0085] The stapler 14 is driven to move from the above-described
second staple position a2 by a predetermined distance L2 in the
direction in which the transversal alignment plates 47a, 47b have
been moved (the direction indicated by arrow A2) and stops at the
third staple position A3 for a stapling operation of the stapling
process. Then, the stapler 14 is driven to move distance L1 in the
opposite direction (the direction indicated by arrow A3) along an
edge of the sheets P and stops at the fourth staple position a4 for
another stapling operation of the stapling process.
[0086] In this way, the stapler 14 is driven to move in the
opposite direction and stops at a plurality of positions for the
stapling process. Since the sheets P are aligned at a position that
corresponds to the distance by which the transversal alignment
plates 47a, 47b are moved, they are stapled always at the right
positions.
[0087] As the stapling operations at the third and fourth staple
positions a3, a4 are completed, the sheets P are conveyed to the
delivery tray 16 (or 18) by the conveyor belt 50 and the
transversal alignment plates 47a, 47b return to the respective
first alignment positions b1, b2 to align the next bundle of sheet
P that are brought in while the staple 14 is driven to slide by the
staple drive section 49 and returns to the first staple position
a1. The above cycle is repeated for the stapling process to
progress.
[0088] Thus, the bundles of sheets T discharged to the delivery
tray 16 (or 18) are placed zigzag vertically but stapled at the
same positions so long as the sheets have the same size. In other
words, the staples gap of a preceding bungle of sheets T and those
of the immediately succeeding bundle of sheets T that are
discharged onto the delivery tray 16 are separated by a constant
gap.
[0089] In the above-described operation of the stapler 14, the
distance L1 from the first staple position a1 to the second staple
position a2, which is equal to the distance from the third staple
position a3 to the fourth staple position a4, is defined by the gap
between the sheet-binding positions, which is about 120 mm.
[0090] The distance L2 from the second staple position a2 to the
third staple position a3 may be appropriately selected so as to
differentiate the staple positions ST at the first alignment
position and the staple positions ST at the second alignment
position. For instance, about 15 mm may be sufficient for the
distance L2. Similarly, about 15 mm may be sufficient for the
distance L2 from the fourth staple position a4 to the first staple
position a1.
[0091] In this way, the stapler 14 is driven to move cyclically
along the staple positions a1.fwdarw.a2.fwdarw.a3 and along the
staple positions a3.fwdarw.a4.fwdarw.a1 according to the alignment
positions of the alignment plates 47a, 47b. The moving distance of
the stapler 14 can be reduced for each cycle if the moving distance
L2 is defined to be not greater than L1/2 for instance. Then, the
moving time can be reduced to realize a high speed stapling
process.
[0092] FIGS. 15A through 15C schematically illustrate how the
bundles of sheets T that have been stapled sequentially discharged
to the delivery tray 16. FIG. 15A shows that bundles of sheets are
brought in and laid zigzag and hence their stapling positions ST
are arranged zigzag. FIG. 15B illustrates how staple positions ST
are arranged in a zigzag manner for bundles T of sheets.
[0093] As shown in FIG. 15B, when sheets of a same size are
stapled, the stapling positions are arranged zigzag without
failling to reduce the height H1 of the stapled bundles of sheets.
Therefore, if a large number of bundles of sheets T are laid on the
delivery tray 16, the height of the heap of staples canbe reduced.
Then, it is possible to minimize the problem that a succeeding
bundle of sheets that is discharged to the delivery tray can force
out one or more than one uppermost bundle of sheets T already
delivered to the delivery tray.
[0094] FIG. 15C illustrates how bundles of sheets T are laid one on
the other by a known sheet post-processing apparatus for the
purpose of comparison. As shown, staples are placed at the same
positions and laid one on the other to raise the height H2 of the
stapled bundles of sheets (H2>H1). Then, the bundles of sheets
on the delivery tray can easily collapse.
[0095] As described above, according to the present invention, it
is possible to minimize the problem that a succeeding bundle of
sheets that is stapled and discharged to the delivery tray 16 (or
18) can force out one or more than one uppermost bundle of sheets
already discharged to the delivery tray to collapse the stack.
Thus, a sheet post-processing apparatus according to the present
invention does not reduce the efficiency of the corresponding image
forming apparatus and hence is convenient to the users.
[0096] The present invention is by no means limited to the
above-described embodiment, which may be modified and altered in
various different ways without departing from the scope of the
invention as defined in claims. For example, while the stapler 14
staples each bundle of sheets at two positions but it may
alternatively staple at three positions.
[0097] Although exemplary embodiments of the present invention have
been shown and described, it will be apparent to those having
ordinary skill in the art that a number of changes, modifications
or alternations to the invention as described herein may be made,
non of which depart fro the spirit of the present invention. All
such changes, modifications and alterations should therefore be
seen as within the scope of the present invention.
* * * * *