U.S. patent application number 13/534305 was filed with the patent office on 2013-01-03 for post-processing apparatus and image forming system.
Invention is credited to Tomohiro KIRIYAMA.
Application Number | 20130001851 13/534305 |
Document ID | / |
Family ID | 47389794 |
Filed Date | 2013-01-03 |
United States Patent
Application |
20130001851 |
Kind Code |
A1 |
KIRIYAMA; Tomohiro |
January 3, 2013 |
POST-PROCESSING APPARATUS AND IMAGE FORMING SYSTEM
Abstract
A post-processing apparatus includes a post-processing unit
performing post-processing for a sheet ejected from a former-stage
apparatus, a post-processing time calculating unit calculating a
time required for the post-processing based on a content of the
post-processing, a time comparing unit comparing the time required
for the post-processing and a sheet interval between sheets ejected
from the former-stage apparatus, an overlapping conveying unit
overlapping a plurality of sheets ejected from the former-stage
apparatus and conveying the overlapping sheets on an upstream side
of the post-processing unit, and a control unit controlling the
overlapping conveying unit, wherein the control unit changes the
number of overlapping sheets in the overlapping conveying unit in
accordance with the sheet interval of sheets ejected from the
former-stage apparatus where the time required for the
post-processing is determined to exceed the sheet interval based on
a comparison result of the time comparing unit.
Inventors: |
KIRIYAMA; Tomohiro; (Kofu,
JP) |
Family ID: |
47389794 |
Appl. No.: |
13/534305 |
Filed: |
June 27, 2012 |
Current U.S.
Class: |
271/3.14 |
Current CPC
Class: |
B65H 2511/31 20130101;
B65H 2801/27 20130101; B42C 1/125 20130101; B65H 2511/30 20130101;
B65H 2513/53 20130101; B65H 2511/31 20130101; B65H 2220/01
20130101; B65H 2301/4213 20130101; B65H 2511/30 20130101; B65H
2513/53 20130101; B65H 29/60 20130101; B65H 2220/03 20130101; B65H
2220/02 20130101 |
Class at
Publication: |
271/3.14 |
International
Class: |
B65H 5/00 20060101
B65H005/00; B65H 29/00 20060101 B65H029/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 1, 2011 |
JP |
2011-147506 |
Claims
1. A post-processing apparatus comprising: a post-processing unit
to perform post-processing for a sheet ejected from a former-stage
apparatus; a post-processing time calculating unit to calculate a
time required for the post-processing based on a content of the
post-processing; a time comparing unit to compare the time required
for the post-processing and a sheet interval between sheets ejected
from the former-stage apparatus with each other; an overlapping
conveying unit to overlap a plurality of sheets ejected from the
former-stage apparatus and convey the overlapping sheets on an
upstream side of the post-processing unit; and a control unit to
control the overlapping conveying unit, wherein the control unit
changes the number of overlapping sheets in the overlapping
conveying unit in accordance with the sheet interval of sheets
ejected from the former-stage apparatus in a case where the time
required for the post-processing is determined to exceed the sheet
interval based on a comparison result of the time comparing
unit.
2. The post-processing apparatus according to claim 1, wherein the
control unit changes the number of overlapping sheets in the
overlapping conveying unit in accordance with the sheet interval of
the sheets ejected from the former-stage apparatus at the time of
maintaining same set in the plurality sets for printing in an image
forming apparatus arranged on a former stage of the post-processing
apparatus.
3. The post-processing apparatus according to claim 1, wherein the
control unit changes the number of overlapping sheets in the
overlapping conveying unit in accordance with the sheet interval of
the sheets ejected from the former-stage apparatus at the time of
occurring different set in the plurality sets for printing in an
image forming apparatus arranged on a former stage of the
post-processing apparatus.
4. The post-processing apparatus according to claim 1, wherein the
control unit performs control of ejecting the sheets overlapped
each other in the overlapping conveying unit toward the
post-processing unit in a case where the post-processing unit
disposed on a downstream side of the overlapping conveying unit is
in a state in which sheets can be received.
5. The post-processing apparatus according to claim 4, wherein the
control unit determines the state in which sheets can be received
based on whether or not the post-processing for sheets sent to the
post-processing unit in advance has been completed.
6. The post-processing apparatus according to claim 4, wherein the
control unit determines the state in which sheets can be received
based on whether or not a predetermined time has elapsed after a
final sheet is sent to the post-processing unit for the
post-processing.
7. The post-processing apparatus according to claim 1, wherein the
former-stage apparatus is an image forming apparatus.
8. The post-processing apparatus according to claim 1, wherein the
former-stage apparatus includes a different type of a
post-processing apparatus that has a post-processing unit other
than the post-processing unit.
9. An image forming system comprising: an image forming apparatus
to form an image and transfer the image to the sheet; a
post-processing apparatus being located on a later stage side of
the image forming apparatus and including a post-processing unit to
perform post-processing for a sheet ejected from a former-stage
apparatus and an overlapping conveying unit to overlap a plurality
of sheets ejected from the former-stage apparatus and convey the
overlapping sheets on an upstream side of the post-processing unit;
a post-processing time calculating unit to calculate a time
required for the post-processing based on a content of the
post-processing; a time comparing unit to compare the time required
for the post-processing and a sheet interval between sheets ejected
from the former-stage apparatus of the post-processing apparatus
with each other; and the control unit according to claim 1.
10. The image forming system according to claim 9, wherein at least
one of a different type of a post-processing apparatus having a
post-processing unit other than the post-processing unit is
connected in sequence to the former stage of the post-processing
apparatus in a later stage side of the image forming apparatus.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a post-processing apparatus
that performs post-processing for a sheet on which an image is
transferred by an image forming apparatus and an image forming
system that includes the image forming apparatus and the
post-processing apparatus.
[0003] 2. Description of the Related Art
[0004] In image forming apparatuses that form images and transfer
the images to a sheet such as a copying machine, a printer, a
facsimile, and a multifunction periphery, post-processing can be
performed for the sheet to which images have been transferred as
desired. Examples of the post-processing include stapling, saddle
stitching, and punching. The post-processing is performed by a
post-processing apparatus that is connected to the later stage side
of an image forming apparatus. In addition, it is not necessary for
the post-processing apparatus to be connected immediately next to
the image forming apparatus.
[0005] In latest image forming apparatuses, implementation of high
speed has progressed so as to improve the productivity, and a time
interval for each sheet (hereinafter, referred to as a sheet
interval) in which the sheet is conveyed is further shortened. On
the other hand, in the post-processing, a processing time according
to the details of the post-processing is necessary, and the
implementation of high speed has not progressed as much as that of
the image processing apparatus. As a result, when the time that is
required for the post-processing is secured, as illustrated in FIG.
7(a) for a case where overlapping conveyance is not performed, it
is necessary to secure a long sheet interval, and there occurs a
problem of degrading the implementation of high speed of the
apparatus.
[0006] Thus, a post-processing apparatus has been proposed which is
configured not to decrease the productivity of an image forming
apparatus by arranging an overlapping conveying unit that allows
sheets to stay (pre-stock) in the post-processing apparatus and can
convey a plurality of the sheets in an overlapping manner (for
example, Patent Literature 1 and 2).
[0007] In Patent Literature 1, a post-processing time is secured by
pre-stocking N sheets that are defined in advance.
[0008] In addition, in Patent Literature 2, in a system that
includes a plurality of stages of post-processing apparatuses, a
time that is necessary for post-processing of a later stage is
acquired, and the timing for ejecting a sheet to the
post-processing apparatus of the later stage is controlled in
accordance with the time by a post-processing apparatus of the
former stage that receives the sheet from an image forming
apparatus.
[0009] When overlapping conveyance is performed, as illustrated in
FIG. 7(b), in a case where a time that is required for the
post-processing is longer than the sheet interval, by performing
overlapping conveyance of sheets corresponding to a number set in
advance therebetween, the post-processing can be performed without
affecting the sheet interval. In the example of this apparatus,
four sheets are conveyed in an overlapping manner. When a case
where overlapping conveyance is not performed, but the sheet
interval is lengthened and a case where the overlapping conveyance
is performed are compared with each other, as illustrated in FIG.
7, at a time point at which a second page of the next bundle is
conveyed in a case where the overlapping conveyance is not
performed, the fifth page of the next bundle can be conveyed in a
case where the overlapping conveyance is performed. It is known
that the productivity can be maintained to be high by performing
overlapping control.
CITATION LIST
Patent Literature
[0010] Patent Literature 1: Japanese Patent Application Laid-Open
No. 2010-159131 [0011] Patent Literature 2: Japanese Patent
Application Laid-Open No. 2010-18399
[0012] However, the number of sheets that are conveyed in an
overlapping manner inside the post-processing apparatus increases
in accordance with the implementation of high speed of the image
forming apparatus. According to the above-described conventional
technique, the number of overlapping sheets is determined based on
sheet information (a sheet size and a post-processing mode) that is
notified in advance, and accordingly, even in a case where the
sheet interval becomes longer due to a factor of a further upstream
side than the post-processing apparatus, the post-processing
apparatus is maintained to wait at an overlapping position until
the set number of overlapping sheets is reached.
[0013] However, as the number of overlapping sheets increases, the
more the number of overlapping sheets is, the higher the
possibility of alignment mismatching is. In addition, in a case
where the number of overlapping sheets is large, there is concern
that the performance of conveyance may deteriorate due to a change
in the sheet status (curling or the like) that is caused by an
environment condition, a sheet condition, and a printing
condition.
[0014] On the other hand, in a case where the number of overlapping
sheets is decreased, the implementation of high speed of the image
forming apparatus is encumbered.
[0015] The invention is devised based on the above-described
situations, and at least one of the object thereof is to provide a
post-processing apparatus and an image forming system that can
resolve problems such as alignment mismatching by decreasing the
number of sheets conveyed by the post-processing apparatus in an
overlapping manner as much as possible without hindering the
implementation of high speed of the image forming apparatus.
SUMMARY OF THE INVENTION
[0016] To achieve at least one of abovementioned objects, a
post-processing apparatus reflecting one aspect of the present
invention comprises:
[0017] a post-processing unit that performs post-processing for a
sheet ejected from a former-stage apparatus;
[0018] a post-processing time calculating unit that calculates a
time required for the post-processing based on a content of the
post-processing;
[0019] a time comparing unit that compares the time required for
the post-processing and a sheet interval between sheets ejected
from the former-stage apparatus with each other;
[0020] an overlapping conveying unit that overlaps a plurality of
sheets ejected from the former-stage apparatus and conveys the
overlapping sheets on an upstream side of the post-processing
unit;
[0021] and a control unit that controls the overlapping conveying
unit, in which the control unit changes the number of overlapping
sheets in the overlapping conveying unit in accordance with the
sheet interval of sheets ejected from the former-stage apparatus in
a case where the time required for the post-processing is
determined to exceed the sheet interval based on a comparison
result of the time comparing unit.
[0022] In the above-described post-processing apparatus, it is
preferred that the control unit changes the number of overlapping
sheets in the overlapping conveying unit in accordance with the
sheet interval of the sheets ejected from the former-stage
apparatus at the time of maintaining same set in the plurality sets
for printing in an image forming apparatus arranged on a former
stage of the post-processing apparatus.
[0023] In addition, in the above-described post-processing
apparatus, it is preferred that the control unit change the number
of overlapping sheets in the overlapping conveying unit in
accordance with the sheet interval of the sheets ejected from the
former-stage apparatus at the time of occurring different set in
the plurality sets for printing in an image forming apparatus
arranged on a former stage of the post-processing apparatus.
[0024] In addition, in the above-described post-processing
apparatus, it is preferred that the control unit perform control of
ejecting the sheets overlapping each other in the overlapping
conveying unit toward the post-processing unit in a case where the
post-processing unit disposed on a downstream side of the
overlapping conveying unit is in a state in which sheets can be
received.
[0025] In addition, in the above-described post-processing
apparatus, it is preferred that the control unit determines the
state in which sheets can be received based on whether or not the
post-processing for sheets sent to the post-processing unit in
advance has been completed.
[0026] In addition, in the above-described post-processing
apparatus, it is preferred that the control unit determines the
state in which sheets can be received based on whether or not a
predetermined time has elapsed after a final sheet is sent to the
post-processing unit for the post-processing.
[0027] In addition, in the above-described post-processing
apparatus, it is preferred that the former-stage apparatus be an
image forming apparatus.
[0028] Furthermore, in the above-described post-processing
apparatus, it is preferred that the former-stage apparatus includes
a different type of a post-processing apparatus that has a
post-processing unit other than the post-processing unit.
[0029] To achieve at least one of abovementioned objects, an image
forming system reflecting one aspect of the present invention
comprises:
[0030] an image forming apparatus to form an image and transfer the
image to the sheet;
[0031] a post-processing apparatus being located on a later stage
side of the image forming apparatus and including a post-processing
unit to perform post-processing for a sheet ejected from a
former-stage apparatus and an overlapping conveying unit to overlap
a plurality of sheets ejected from the former-stage apparatus and
convey the overlapping sheets on an upstream side of the
post-processing unit;
[0032] a post-processing time calculating unit to calculate a time
required for the post-processing based on a content of the
post-processing;
[0033] a time comparing unit to compare the time required for the
post-processing and a sheet interval between sheets ejected from
the former-stage apparatus of the post-processing apparatus with
each other; and
[0034] the control unit according to any one of the above-described
post-processing apparatus.
[0035] In the above-described the image forming system, it is
preferred that at least one of a different type of a
post-processing apparatus having a post-processing unit other than
the post-processing unit is connected in sequence to the former
stage of the post-processing apparatus in a later stage side of the
image forming apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0036] FIG. 1 is a cross-sectional view that illustrates the
mechanical configuration of an image forming system that includes a
post-processing apparatus according to an embodiment of the
invention.
[0037] FIG. 2 is a diagram that illustrates an example of the
operation of an overlapping conveying unit.
[0038] FIG. 3 is a control block diagram.
[0039] FIG. 4 is a diagram that illustrates overlapping and
conveying control operations.
[0040] FIG. 5 is a diagram that illustrates another example of the
overlapping and conveying control operation.
[0041] FIG. 6 is a flowchart that illustrates the sequence of the
overlapping and conveying control operation,
[0042] FIG. is a diagram that illustrates conventional sheets
conveying and overlapping.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] Hereinafter, an embodiment of the invention is
described.
[0044] As illustrated in FIG. 1, an image forming system is
configured by an image forming apparatus 1, a first post-processing
apparatus 2 that is connected to a later stage of the image forming
apparatus 1, and a second post-processing apparatus 3 that is
connected to a later stage of the first post-processing apparatus
2. The second post-processing apparatus 3 corresponds to a
post-processing apparatus according to an embodiment of the
invention, and the above-described image forming system corresponds
to an image forming system according to an embodiment of the
invention.
[0045] A post-processing unit included in the post-processing
apparatus performs predetermined post-processing for sheets ejected
from the former stage, and the type of the post-processing is not
particularly limited. Examples of the post-processing include
stapling, saddle stitching, punching, and a binding process as
illustrated FIG. 1. In addition, in the post-processing
apparatuses, post-processing units that perform one type of
post-processing may be included or post-processing units that
perform a plurality of types of post-processing may be
included.
[0046] Generally, although an image forming apparatus is connected
to the former stage side of the post-processing apparatus, it is
not necessary for an image forming apparatus to be connected to the
former stage of the post-processing apparatus, but a different type
of a post-processing apparatus that has a post-processing unit
other than the post-processing unit or any other apparatus may be
connected thereto.
[0047] FIG. 1 is a cross-sectional view that illustrates the
mechanical structure of an image forming system.
[0048] First, the image forming apparatus 1 will be described.
[0049] In the image forming apparatus 1, reference numeral 7 is a
sheet feeding unit, reference numeral 8 is a document reading unit,
and reference numeral 10 is an image forming unit.
[0050] The document reading unit 8 reads an image of a document
that is conveyed by an automatic document feeding device (not
illustrated in the figure) or a document that is arranged on a
platen and temporarily records the image in an image memory, which
is not illustrated in the figure, or the like.
[0051] The image forming unit 10 includes photosensitive bodies
11C, 11M, 11Y, and 11K that are prepared for colors (cyan, magenta,
yellow, black, and the like), and, across peripheral line portions
of the photosensitive bodies 11C, 11M, 11Y, and 11K, chargers 12C,
12M, 12Y, and 12K, writing units 13C, 13M, 13Y, and 13K, and
developing units 14C, 14M, 14Y, and 14K are arranged. Accordingly,
the surfaces of the photosensitive bodies 11C, 11M, 11Y, and 11K
that are charged by the chargers 12C, 12M, 12Y, and 12K are exposed
for images by the writing units 13C, 13M, 13Y, and 13K based on
image information of the document that is recorded in the image
memory or the like, and latent images are formed on the surfaces of
the photosensitive bodies 11C, 11M, 11Y, and 11K. The latent images
are developed by the developing units 14C, 14M, 14Y, and 14K so as
to be formed as toner images. The toner images are transferred to
an intermediate transfer belt 16 and are transferred from the
intermediate transfer belt 16 to a sheet that is conveyed by a
sheet feeding unit 20. The sheet to which the toner images have
been transferred is heated so as to be fixed by a fixing unit 18,
and image forming output (printing) is performed to a sheet
ejecting unit 19.
[0052] In addition, in the image forming unit 10, cleaning units
15C, 15M, 15Y, and 15K are arranged in correspondence with the
photosensitive bodies, which remove remaining toner by being
brought into contact with the photosensitive bodies 11C, 11M, 11Y,
and 11K on a further rotation direction side than a contact
position with the intermediate transfer belt 16 and on a further
reverse rotation direction side than the chargers 12C, 12M, 12Y,
and 12K. In addition, a cleaning unit 17 that removes remaining
toner remaining on the intermediate transfer belt 16 is arranged on
a further rotation direction side than a sheet transfer position of
the intermediate transfer belt 16 and a further reverse rotation
direction side than transfer positions of the photosensitive
bodies.
[0053] Furthermore, in the image forming apparatus 1, the sheet
feeding unit 7 that includes a plurality of sheet feeding trays in
which sheets are housed is arranged on the lower side of the image
forming unit 10. In addition, a sheet conveying unit 9 is included,
which extends from the sheet feeding trays to the image forming
unit 10 and from the image forming unit 10 to the sheet ejecting
unit 19, and sheets are conveyed through the sheet conveying unit 9
at a predetermined sheet interval.
[0054] The photosensitive bodies 11C, 11M, 11Y, and 11K are driven
to rotate by a driving motor, which is not illustrated in the
figure, and the intermediate transfer belt 16 are driven to rotate
with by a driving motor not illustrated in the figure.
[0055] The first post-processing apparatus 2 includes a fixing unit
20 as a second fixing unit, as a fixing unit 18 provided in the
image forming apparatus 1 is a first fixing unit. The fixing unit
20 performs second fixing by heating and compressing the sheet
after receiving the sheet ejected from the sheet ejecting unit 19
of the image forming apparatus 1 in the fixing unit 20. On the
sheet ejecting side of the second fixing unit 20, a first conveying
path 22 and a second conveying path 23 that are provided a
switching unit 21 are included. The first conveying path 22 conveys
a sheet ejected from the fixing unit 20 to the sheet ejecting unit
25 so as to be ejected to the second post-processing apparatus 3.
The second conveying path 23 conveys a sheet ejected from the
fixing unit 20 to the image forming apparatus 1 and passes the
sheet to a conveying path 9, thereby enabling to form an image
again in the image forming apparatus 1.
[0056] The second post-processing apparatus 3 includes a main
conveying path 30 that is used for receiving a sheet ejected from
the first post-processing apparatus 2 and can convey a sheet to an
overlapping conveying unit 32 through a switching unit 31. The main
conveying path 30 extends downward through the switching unit 31,
and a switching unit 33 is interposed on the lower side thereof.
The main conveying path 30 that is disposed immediately behind the
switching unit 33 on the lower side also serves as a sheet standby
unit. In one switching direction of the switching unit 33, an
overlapping path 34 is disposed.
[0057] The overlapping conveying unit 32 is configured by a part of
the main conveying path, the switching unit 31, the switching unit
33, the overlapping path 34, and the like.
[0058] In addition, a stack conveying path 35, which is formed
through the switching unit 33, is disposed, and a stack unit 36 is
disposed in the conveying direction of the stack conveying path
35.
[0059] At the conveyance destination of the main conveying path 30,
a post-processing unit 37 is disposed. In this embodiment, as
post-processing, flat stitching is performed in the post-processing
unit 37. In this figure, the configuration of the post-processing
unit 37 is simplified. A sheet ejecting unit 38 is disposed on the
downstream side of the post-processing unit 37.
[0060] As described above, the post-processing apparatus according
to the present embodiment includes the overlapping conveying unit
that can overlap sheets and convey the overlapped sheets on the
upstream side of the post-processing unit. This overlapping
conveying unit can overlap and convey sheets corresponding to
different number of overlapping sheets. Here, the structure of the
overlapping conveying unit is not particularly limited and may be a
structure in which sheets of a predetermined number ejected from an
apparatus of the former stage can be overlapped and conveyed in an
overlapping manner on the upstream side of the post-processing
unit.
[0061] The overlapping conveying unit ejects sheets in a state in
which the sheets can be received by the post-processing unit and,
for example, conveys the sheets to the stack unit.
[0062] The overlapping conveying unit is controlled by a control
unit. In a case where the time required for the post-processing is
equal to or shorter than the sheet interval based on a comparison
result of a time comparing unit, the control unit sets an operation
of conveying sheets in an overlapping manner by the overlapping
conveying unit to be unnecessary. In the present embodiment, it is
not excluded to overlap and convey sheets corresponding to a
minimum number of overlapping sheets in an overlapping manner even
in a case where the time required for the post-processing is equal
to or shorter than the sheet interval.
[0063] On the other hand, in a case where the time required for the
post-processing exceeds the sheet interval, the control unit
controls the overlapping conveying unit to overlap and convey
sheets in an overlapping manner. In addition, at this time, the
number of overlapping sheets may be changed in accordance with the
degree of an excess of the time required for the post-processing
over the sheet interval. In the control, it is preferable that the
number of overlapping sheets is set to a requisite minimum number
that does not affect the sheet interval. In the case of the number
of overlapping sheets that has not arrived at the requisite
minimum, it is difficult to overlap and convey sheets without
increasing the sheet interval, whereby the productivity decreases.
On the other hand, in a case where overlapping and conveying is
performed with the number of sheets that exceeds the requisite
minimum number of overlapping sheets, although it does not affect
the productivity, the number of overlapping sheets is excessive,
whereby a decrease in the conveyance precision, alignment
mismatching, or the like may easily occur.
[0064] The control unit may be arranged inside the casing of the
post-processing apparatus or may be arranged outside the
post-processing apparatus, for example, inside the casing of the
image forming apparatus or inside the casing of an external device
that is connected to a LAN connected to the casing of the
post-processing apparatus.
[0065] The operation of the overlapping conveying unit 32 will be
described with reference to FIG. 2.
[0066] A sheet P1 that is received in the main conveying path 30 of
the second post-processing apparatus 3 is conveyed along the main
conveying path 30 by the switching operation of the switching unit
31 and is conveyed to the overlapping path 34 as the overlapping
unit by the switching operation of the switching unit 33 (FIG.
2(a)). When the rear end of the sheet P1 passes through the
switching unit 33, the sheet P1 that has been sent to the
overlapping path 34 in accordance with the reverse rotation of
conveying rollers is switched back and stands by at the main
conveying path 30 that is located on the downstream side of the
switching unit 33 (FIG. 2(b)). Thereafter, when the next sheet P2
is received from the former stage, while the previous sheet P1
stands by at the main conveying path 30 on the downstream side of
the switching unit 33, the sheet P2 is conveyed to the main
conveying path 30 on the upstream side and passes through the
switching unit 31, and the front end of the sheet P2 is stopped
immediately before the switching unit 33. The sheets P2 and P1 are
sent to the overlapping path 34 in a same period so as to overlap
each other (FIG. 2(d)), and, when the rear end passes through the
switching unit 33, both sheets P1 and P2 are switched back together
and stand by in an overlapping state at the main conveying path 30
on the downstream side of the switching unit 33 (FIG. 2(e)).
[0067] When the post-processing unit 37 can receive sheets, the
sheets P1 and P2 are conveyed in the overlapping state to the stack
unit 36 that is included in the post-processing unit 37 through the
stack conveying path 35 (FIG. 2(f)).
[0068] When the number of sheets conveyed to the stack unit 36
arrives at a predetermined number of sheets of a bundle, the sheets
are conveyed to the post-processing unit 37, and predetermined
post-processing is performed for the sheets.
[0069] In the description presented above, although an example has
been described in which two sheets are overlapped and conveyed in
an overlapping manner, by repeating the above-described sequence,
overlapping and conveying of three or more sheets can be
performed.
[0070] In addition, generally, there is a limit of the number of
sheets in the overlapping conveying unit 32, which can be
overlapped and conveyed in an overlapping manner, due to a
structural reason, and conveyance can be performed by changing the
number of overlapping sheets within this limit. Furthermore, an
embodiment of the invention is not limited to a specific number of
overlapping sheets.
[0071] The sheets overlapping each other stand by in the
overlapping conveying unit until the sheets can be received by the
post-processing unit as described above, and, after the sheets can
be received by the post-processing unit, the sheets are ejected
from the overlapping conveying unit. It can be determined whether
or not sheets can be received based on whether or not the
post-processing of the previous bundle of sheets or the like has
been completed. In addition, it can be determined whether or not
sheets can be received also based on whether or not a predetermined
time elapses after the final sheet is sent to the post-processing
unit for the post-processing. The time until the post-processing is
completed after the final sheet is sent can be determined, and,
after a predetermined time required for not interfering with the
previous bundle elapses, the sheets may be ejected without any
problem even when the post-processing is not completed.
[0072] Next, control blocks of the image forming system will be
described.
[0073] The image forming apparatus 1 includes an image forming
apparatus control unit 100 that controls the overall operation of
the image forming apparatus 1, and a sheet feeding unit 7, a sheet
conveying unit 9, an image forming unit 10, and an image processing
unit 113 are connected to the image forming apparatus control unit
100 in a controllable manner. The image forming apparatus control
unit 100 acquires the sheet interval that is a conveyance interval
of sheets based on the operating conditions of the image forming
apparatus 1. The image processing unit 113 performs image
processing such as analog processing, A/D conversion, shading
correction, and image compressing process for image data that is
acquired by a scanner, which is not illustrated in the figure, or
the like based on an instruction transmitted from the image forming
apparatus control unit 100.
[0074] In the sheet feeding unit 7, a sheet is fed from a
predetermined sheet feeding tray under the control of the image
forming apparatus control unit 100, and conveyance of the sheet
from the image forming unit 10 to the sheet ejecting unit 19 is
performed by the sheet conveying unit 9 that is controlled by the
image forming apparatus control unit 100. In the image forming unit
10, image processing and the like are performed by the image
processing unit 113, and an image is written in each color based on
the image data that is temporarily stored in a storage unit or the
like, thereby performing formation of the image, transfer of the
image to the sheet, and the like.
[0075] In addition, a sheet feed switching unit 101 is connected to
the image forming apparatus control unit 100 in a controllable
manner. The sheet feed switching unit 101 performs switching
between sheet feeding trays from which a sheet is fed, and, for
example, serves its function at a time when automatic switching
between sheet feeding trays is performed due to being out of paper
in a sheet feeding tray that currently feeds a sheet, a time when
switching between sheet feeding trays is performed at a switching
period set in advance, or the like. There is a case where the sheet
interval changes when switching between sheet feeding trays is
performed, and the image forming apparatus control unit 100
acquires a change in the sheet interval that is accompanied with
sheet feed switching as information.
[0076] Furthermore, a heating unit 110, a temperature detecting
unit 111 and a warm-up completion time calculating unit 112 are
connected to the image forming apparatus control unit 100 in a
controllable manner. The heating unit 110 and the temperature
detecting unit 111 are provided in the fixing unit 18, and the
fixing unit 18 is heated up to a predetermined temperature by the
heating unit 110. The temperature at that time is detected by the
temperature detecting unit 111, and the image forming apparatus
control unit 100 that receives a detection result of the
temperature detecting unit 111 performs heat control through the
heating unit 110. In addition, a warm-up completion time that is a
time until fixing unit 18 can be operated through heating performed
by the heating unit 110 is calculated by the warm-up completion
time calculating unit 112. The warm-up completion time calculating
unit 112 can calculate the warm-up completion time based on the
detection temperature detected by the temperature detecting unit
111, a trend of the change in detection temperature, or the
like.
[0077] In addition, a serial communication unit 115 is connected to
the image forming apparatus control unit 100 in a controllable
manner. The serial communication unit 115 is configured to be
communicable with the first post-processing apparatus of the later
stage.
[0078] Furthermore, a time comparing unit 102 is connected to the
image forming apparatus control unit 100. The time comparing unit
102 compares the sheet interval and a time required for
post-processing performed by the second post-processing apparatus
3. The image forming apparatus control unit 100 is notified of the
comparison result. The information of the sheet interval is
acquired by the image forming apparatus control unit 100 based on
the operation of the image forming apparatus 1 and is also acquired
based on a detection result acquired by the second post-processing
apparatus 3 to be described later. As an embodiment of the
invention, the number of overlapping sheets may be determined by
using the information of the sheet interval of only one side.
[0079] The image forming apparatus control unit 100 receives the
comparison result, compares the time required for post-processing
and the sheet interval with each other, and determines the
overlapping conveyance performed in the second post-processing
apparatus 3. In a case where the time required for post-processing
is equal to or shorter than the sheet interval, the overlapping
conveyance to be performed in the second post-processing apparatus
3 is determined to be unnecessary. On the other hand, in a case
where the time required for post-processing exceeds the sheet
interval, the overlapping conveyance is determined to be necessary,
and a requisite minimum number of overlapping sheets that is
required for the overlapping conveyance is determined in accordance
with the degree of an excess of the time required for the
post-processing over the sheet interval under a condition that the
post-processing can be performed without affecting the sheet
interval.
[0080] The second post-processing apparatus 3 is notified of the
determination result of the overlapping conveyance, which is
acquired by the image forming apparatus control unit 100, through
the serial communication unit 115 and further through the first
post-processing apparatus 2.
[0081] The determination of the number of overlapping sheets may be
performed at a time when the sheet interval changes, for every time
when a sheet is conveyed, for every time when sheets of a
predetermined number are conveyed, or the like.
[0082] For example, in a case where there is an unexpected factor
in the image forming apparatus 1 or there is a factor causing the
sheet interval to change in the later stage side of the image
forming apparatus 1, for example, in the first post-processing
apparatus 2 after the number of overlapping sheets is determined
based on the sheet interval that is derived based on the operating
conditions of the image forming apparatus 1, by changing the number
of overlapping sheets based on the sheet interval that is detected
by the second post-processing apparatus 3 or the like, the number
of overlapping sheets that is appropriate to the situation can be
determined.
[0083] The first post-processing apparatus 2 includes a first
post-processing apparatus control unit 200 that controls the
overall operation of the first post-processing apparatus 2, and an
upper-stage serial communication unit 201 is connected to the first
post-processing apparatus control unit 200 in a controllable
manner. The upper-stage serial communication unit 201 is connected
to the serial communication unit 115 of the image forming apparatus
1 so as to be communicable.
[0084] In addition, a lower-stage serial communication unit 202 is
connected to the first post-processing apparatus control unit 200
in a controllable manner, and the first post-processing apparatus
control unit 200 is configured to be communicable with the second
post-processing apparatus 3 disposed on the later stage through the
lower-stage serial communication unit 202.
[0085] Furthermore, a sheet conveying unit 205 is connected to the
first post-processing apparatus control unit 200 in a controllable
manner. The sheet conveying unit 205 conveys a sheet ejected from
the image forming apparatus 1 disposed on the previous stage,
conveys the sheet to the image forming apparatus 1 or the second
post-processing apparatus 3 disposed on the later stage, and is
configured by the switching unit 21, the first conveying path 22,
and the second conveying path 23 described above.
[0086] In addition, a heating unit 210, a temperature detecting
unit 211, and a warm-up completion time calculating unit 212 are
connected to the first post-processing apparatus control unit 200
in a controllable manner. The heating unit 210 and the temperature
detecting unit 211 are provided in the fixing unit 20, and the
fixing unit 20 is heated up to a predetermined temperature by the
heating unit 210. The temperature at that time is detected by the
temperature detecting unit 211, and the first post-processing
apparatus control unit 200 that receives a detection result of the
temperature detecting unit 211 performs heat control through the
heating unit 210. In addition, a warm-up completion time that is a
time until fixing unit 20 can be operated through heating performed
by the heating unit 210 is calculated by the warm-up completion
time calculating unit 212. The warm-up completion time calculating
unit 212 can calculate the warm-up completion time based on the
detection temperature detected by the temperature detecting unit
211, a trend of the change in detection temperature, or the
like.
[0087] The second post-processing apparatus 3 includes a second
post-processing apparatus control unit 300 that controls the
overall operation of the second post-processing apparatus 3, and an
upper-stage serial communication unit 301 is connected to the
second post-processing apparatus control unit 300 in a controllable
manner. The upper-stage serial communication unit 301 is connected
to the lower-stage serial communication unit 202 of the first
post-processing apparatus 2 so as to be communicable therewith. As
a result, the second post-processing apparatus 3 can communicate
with the first post-processing apparatus 2 and can communicate with
the image forming apparatus 1 through the first post-processing
apparatus 2.
[0088] A sheet conveying unit 302, an overlapping conveying unit
32, and a sheet detecting unit 303 are connected to the second
post-processing apparatus control unit 300 in a controllable
manner. The sheet conveying unit 302 conveys a sheet ejected from
the first post-processing apparatus 2 of the former stage within
the second post-processing apparatus 3 and includes a main
conveying path 30, a switching unit 31, a switching unit 33, an
overlapping path 34, a stack conveying path 35, and the like.
[0089] In addition, the overlapping conveying unit 32 is configured
by a part of the main conveying path 30, the switching unit 33, the
overlapping path 34, the stack conveying path 35, and the like. In
the second post-processing apparatus control unit 300, overlapping
and conveying of sheets is performed in accordance with the number
of overlapping sheets that is determined by comparing the time
required for post-processing performed by the post-processing unit
37 with the sheet interval. In a case where the overlapping
conveyance is unnecessary, the overlapping conveyance is not
performed.
[0090] Accordingly, the second post-processing apparatus control
unit 300 corresponds to a control unit according to an embodiment
of the invention.
[0091] The sheet detecting unit 303 is arranged in the main
conveying path 30, detects a sheet that is conveyed, and the
detection result is used for controlling the switching units 31 and
33, the conveyance of the sheet, and the like. In addition, the
second post-processing apparatus control unit 300 can acquire a
sheet interval between sheets that are conveyed within the second
post-processing apparatus 3 based on the sheet detecting result
acquired by the sheet detecting unit 303. The information of the
sheet interval that is acquired by the second post-processing
apparatus control unit 300 is transmitted to the image forming
apparatus 1.
[0092] The post-processing unit 37 is connected to the second
post-processing apparatus control unit 300 in a controllable
manner. In the post-processing unit 37, flat stitching is
performed.
[0093] In addition, a post-processing time calculating unit 310 is
connected to the second post-processing apparatus control unit 300.
The post-processing time calculating unit 310 calculates a
processing time that is required for the post-processing unit 37.
In the calculation process, a calculation is performed in
consideration of the number of sheets, the type of the sheets to be
stitched in a flat manner, and the like. The calculation result
acquired by the post-processing time calculating unit 310 is
transmitted to the second post-processing apparatus control unit
300. The image forming apparatus 1 is notified of the calculation
result through the upper-stage serial communication unit 301 and
the first post-processing apparatus 2 by the second post-processing
apparatus control unit 300. The calculation result is received by
the serial communication unit 115 and is transmitted to the image
forming apparatus control unit 100. The image forming apparatus
control unit 100 transmits the calculation result to the time
comparing unit 102 so as to be provided for the comparison of the
time required for the post-processing and the sheet interval.
[0094] Since the time that is required for post-processing differs
depending on factors such as the number of sheets forming a bundle
in the post-processing, the content of the post-processing, the
type of sheets, and the processing capability of the
post-processing apparatus, generally, such factors are prepared as
parameters in advance, so that the time required for the
post-processing can be calculated by the post-processing time
calculating unit. The post-processing time calculating unit can be
configured by a CPU, a program that operates the CPU, a storage
unit in which the parameters and the like are stored, and the like.
Among the above-described factors, the number of sheets, the
content of the post-processing, the type of sheets, and the like
are acquired as information by the image forming apparatus, and the
information can be used for the above-described calculation
process. In addition, information according to the configuration of
the post-processing apparatus such as the processing capability of
the post-processing apparatus may be maintained by the
post-processing apparatus or may be acquired in advance by the
image forming apparatus to which the post-processing apparatus is
connected.
[0095] The post-processing time calculating unit may be arranged
inside the casing of the post-processing apparatus or may be
arranged outside the post-processing apparatus, for example, inside
the casing of the image forming apparatus or inside the casing of
an external device that is connected to a LAN connected to the
casing of the post-processing apparatus.
[0096] The sheet interval of sheets ejected from the former stage
is acquired as information on the former stage side, and the
information can be used. Alternatively, the information relating to
the sheet interval may be acquired by arranging a sensor that
detects a sheet interval in the former stage side or in the
post-processing apparatus, or the like. In addition, both the sheet
interval acquired as the information by the former stage side and
the detection result acquired by the sensor may be used together.
In such a case, even in a case where the sheet interval become
particularly larger than that of a general case, the number of
overlapping sheets can be appropriately changed based on the
detection result regardless of the information of the sheet
interval that is acquired on the former stage side.
[0097] The sheet interval also is changed by performing image
adjustment in the image forming unit that is arranged in the image
forming apparatus, changing a sheet feeding tray (sheet feeding
stage) of sheets to which images are transformed, or changing the
type of sheets.
[0098] Accordingly, the information of the sheet interval that is
acquired on the image forming apparatus side is also changed in
accordance with the changes in the situation.
[0099] The time required for post-processing that is calculated by
the post-processing time calculating unit and the sheet interval
are compared with each other by the time comparing unit. Here, it
is determined whether the time required for the post-processing is
longer than the sheet interval or the time required for the
post-processing is equal to or shorter than the sheet interval. The
time comparing unit may be arranged inside the casing of the
post-processing apparatus or may be arranged outside the
post-processing apparatus, for example, inside the casing of the
image forming apparatus or inside the casing of an external device
that is connected to a LAN connected to the casing of the
post-processing apparatus.
[0100] In addition, a post-processing unit entrance availability
determining unit 311 is connected to the second post-processing
apparatus control unit 300. The post-processing unit entrance
availability determining unit 311 determines whether or not
post-processing has been completed and a sheet can be entered. In
addition, even in a case where the post-processing has not been
completed, it is determined whether a final page of a bundle for
which the post-processing is performed has passed based on the
detection result acquired by the sheet detecting unit 303. In this
determination process, an elapsed time after the passage of the
sheet is measured, and it is determined whether or not the elapsed
time has passed a predetermined time. The predetermined time is a
time in which the final page is stacked in the stack unit 36 and is
conveyed to the post-processing unit 37 side, and a next sheet can
be received by the stack unit 36, and, as it reaches the time, the
next sheet can be conveyed to the stack unit 36 without being
interfered with the sheets of the previous bundle. Even in such a
case, it is determined that the entrance to the post-processing
unit can be performed.
[0101] Next, a state in which overlapping and conveying is
controlled to be performed by the second post-processing apparatus
3 will be described with referring to FIG. 4.
[0102] FIG. 4(a) illustrates a state in which a time required for
post-processing is as expected, and the post-processing can be
performed without affecting the sheet interval by performing
overlapping and conveying with a predetermined number of
overlapping sheets (for example, four sheets).
[0103] However, in a case where the sheet interval becomes larger
due to a factor of the main body of the image forming apparatus 1,
it is necessary to perform overlapping and conveying, and the
overlapping and conveying is performed with a predetermined number
of overlapping sheets (FIG. 4(b)). However, even when a state is
formed in which the sheet interval becomes sufficiently larger, and
the overlapping conveyance is unnecessary, the overlapping and the
conveying with the predetermined number of sheets are performed.
This example corresponds to a conventional overlapping conveyance
operation.
[0104] On the other hand, according to an embodiment of the
invention, when overlapping and conveying is determined to be
unnecessary based on the state of the sheet interval, the
overlapping and conveying is not performed any more, and the number
of overlapping sheets can be set to a requisite minimum number. In
FIG. 4(c), since the sheet interval becomes sufficient during the
overlapping and conveying operation, the overlapping and conveying
operation is stopped at a time point when the sheet interval is
secured, and the number of overlapping sheets is limited to two,
whereby the number of overlapping sheets can be minimized.
[0105] According to the present embodiment, the number of
overlapping sheets in the overlapping conveying unit can be changed
in accordance with the relation between the time required for the
post-processing and the sheet interval, and, in a case where the
time required for the post-processing is longer than the sheet
interval, a minimum requisite number of overlapping sheets is set,
and the number of sheets can be decreased. Accordingly, the
overlapping and conveying can be performed without determining the
number of overlapping sheets in advance. On the other hand, in a
case where the time required for the post-processing is equal to or
shorter than the sheet interval, the post-processing can be
performed without overlapping sheets in the overlapping conveying
unit.
[0106] Another example will be described with reference to FIG.
5.
[0107] In this example, a case is considered in which the sheet
interval becomes larger due to a factor of the first
post-processing apparatus.
[0108] FIG. 5(a) illustrates a state in which a time required for
post-processing is as expected, and the post-processing can be
performed without affecting a sheet interval. The overlapping and
conveying state is not illustrated.
[0109] FIG. 5(b) illustrates a state in which a sheet interval
becomes larger due to a factor of the first post-processing
apparatus.
[0110] In FIG. 5(c), the number of sheets that are overlapped and
conveyed in an overlapping manner is changed in accordance with a
sheet interval, a requisite minimum sheet interval is secured, and
the overlapping and conveying is stopped so as to minimize the
number of overlapping sheets.
[0111] Next, the sequence of a control process in which the number
of overlapping sheets in the overlapping conveying unit is changed
in accordance with the sheet interval between sheets will be
described with reference to flowcharts illustrated in FIG. 6. The
sequence of the control process is performed by the second
post-processing apparatus control unit 300.
[0112] In the sequence illustrated in FIG. 6(a), a sheet ejected
from the first post-processing apparatus 2 is introduced into the
second post-processing apparatus 3 so as to start conveyance in
Step s1, and the conveyance is detected by the sheet detecting unit
303 in the main conveying path 30 in Step s2. The process waits
until detection of the conveyance is made (No in Step s2), and when
the detection of conveyance is made (Yes in Step s2), it is
determined whether or not a previous bundle is in the middle of the
post-processing in Step s3. In a case where the previous bundle is
not in the middle of the post-processing (No in Step s3), the
conveyed sheet is ejected to the post-processing unit in Step s4.
On the other hand, in a case where the previous bundle is in the
middle of the post-processing (Yes in Step s3), the sheet is
conveyed to the overlapping conveying unit 32 in Step s5. When the
conveyance of the sheet to the overlapping conveying unit 32 is
performed, sheets are conveyed to the overlapping conveying unit
with the number of overlapping sheets that is determined based on a
comparison of the time required for the post-processing and the
sheet interval. In addition, in this embodiment, although the
comparison of the time required for the post-processing and the
sheet interval and the determination of the number of overlapping
sheets are performed by the image forming apparatus, the comparison
and the determination may be performed by the second
post-processing apparatus 3. Furthermore, in a case where a sheet
may not be ejected to the post-processing unit, and the number of
overlapping sheets in the overlapping unit arrives at an upper
limit so as to cause a problem, it is necessary to increase the
sheet interval.
[0113] The time that is required for the post-processing can be
acquired through the sequence illustrated in FIG. 6(c).
[0114] The sheet information is acquired from the image forming
apparatus 1 in Step s20, and the post-processing information is
further acquired in Step s21. In the second post-processing
apparatus 3, information that is necessary for the post-processing
can be calculated based on the above-described information by the
post-processing time calculating unit 310.
[0115] The sequence of a control process in which sheets are
ejected to the post-processing unit in a state that sheets are
overlapped with each other in the overlapping conveying unit will
be described with reference to the flowchart illustrated in FIG.
6(b).
[0116] It is checked whether or not a sheet can be received by the
post-processing unit 37 in Step s10.
[0117] The process waits with the check of the result until a next
sheet can be received by the post-processing unit 37 (No in Step
s11, then return to Step s10). When the next sheets can be received
by the post-processing unit 37 (Yes in Step s11), the next sheets
are ejected to the post-processing unit 37 in Step s12.
[0118] Next, a detailed sequence of Step s10 in which it is checked
whether or not a sheet can be received by the post-processing unit
37 will be described with reference to the flowchart illustrated in
FIG. 6(d).
[0119] First, it is determined whether or not a state is formed in
which sheets can enter into the post-processing unit 37 in Step
s30. When the post-processing is completed by the post-processing
unit 37, sheets can be entered into the post-processing unit 37
(Yes in Step s30). When sheets can be entered into the
post-processing unit 37, it is checked that the sheet can be
ejected to the post-processing unit, and the process ends.
[0120] On the other hand, in a case where sheets can not be entered
into the post-processing unit 37 (No in Step s30), it is determined
whether or not a required time elapses after the passage of the
final sheet of the previous bundle in Step s31. This required time
is a time in which the next sheets can be entered into the
post-processing unit without being interfered with the previous
bundle in the post-processing unit even when the next sheets are
started to convey to the post-processing unit at that timing. This
time is acquired the information in advance by acquiring it when
the time required for the post-processing is acquired or the
like.
[0121] When the required time elapses after the passage of the
final page of the previous bundle (Yes in Step s31), it is
determined that sheets can be ejected in Step s32. On the other
hand, when the required time has not elapsed after the passage of
the final page of the previous bundle (No in Step s31), the process
ends without determining that sheets can be ejected.
[0122] According to the embodiment of the invention, since
overlapping sheets of a minimum number can be overlapped and
conveyed in an overlapping manner by an overlapping conveying unit,
improved alignment of sheets can be secured. In addition, a time in
which the overlapping state is maintained by the overlapping
conveying unit can be shortened.
[0123] Furthermore, in a case where it is desired to convey the
minimum overlapping number of sheets, it is not necessary to be
aware of a post-processing apparatus that is connected to the
upstream side.
[0124] As above, while the above-described embodiment of the
invention has been presented, the invention is not limited to the
content of the above-described embodiment, and an appropriate
change can be made therein in the range not departing from the
scope of the invention.
* * * * *