U.S. patent application number 13/013014 was filed with the patent office on 2011-05-19 for sheet post-processing apparatus.
This patent application is currently assigned to TOSHIBA TEC KABUSHIKI KAISHA. Invention is credited to Yoshiaki Sugizaki.
Application Number | 20110115152 13/013014 |
Document ID | / |
Family ID | 39732515 |
Filed Date | 2011-05-19 |
United States Patent
Application |
20110115152 |
Kind Code |
A1 |
Sugizaki; Yoshiaki |
May 19, 2011 |
SHEET POST-PROCESSING APPARATUS
Abstract
A sheet post-processing apparatus includes a sheet aligning
device that increases, when the number of sheets conveyed thereto
exceeds a predetermined number, the number of times of an aligning
operation of the sheet aligning device, which aligns the sheets
conveyed thereto, to be larger than the number of times of the
aligning operation at the number of sheets equal to or smaller than
this predetermined number.
Inventors: |
Sugizaki; Yoshiaki;
(Sunto-gun, JP) |
Assignee: |
TOSHIBA TEC KABUSHIKI
KAISHA
Tokyo
JP
|
Family ID: |
39732515 |
Appl. No.: |
13/013014 |
Filed: |
January 25, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12885771 |
Sep 20, 2010 |
7896334 |
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13013014 |
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11681523 |
Mar 2, 2007 |
7862025 |
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12885771 |
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Current U.S.
Class: |
271/207 |
Current CPC
Class: |
B42C 1/125 20130101;
B65H 2801/27 20130101; B65H 31/34 20130101; B65H 2513/51 20130101;
B65H 2511/13 20130101; B65H 2511/30 20130101; B65H 2511/30
20130101; B65H 2220/01 20130101; B65H 2513/51 20130101; B65H
2220/02 20130101; B65H 2511/13 20130101; B65H 2220/01 20130101 |
Class at
Publication: |
271/207 |
International
Class: |
B65H 31/00 20060101
B65H031/00 |
Claims
1. A sheet post-processing apparatus comprising: a processing tray
that receives sheets subjected to image formation from an image
forming apparatus; a sheet discharge tray that stacks the sheets
discharged after processing in a post process; and a sheet aligning
device having: a vertical aligning device that aligns the sheets
conveyed thereto in a conveying direction, a horizontal aligning
device that includes a first aligning plate and a second aligning
plate, which nip the sheets conveyed to the processing tray in a
direction perpendicular to the conveying direction, and moves the
first aligning plate and the second aligning plate in a direction
of the sheets and presses the sheets, thereby aligning the sheets
in the direction perpendicular to the conveying direction, and a
control unit that controls aligning operations of the vertical
aligning device and the horizontal aligning device and increases,
when a number of the sheets conveyed thereto exceeds a
predetermined number, an amount of movement of the first aligning
plate or the second aligning plate in the sheet direction to be
larger than an amount of movement at a number of sheets equal to or
smaller than the predetermined number of sheets.
2. A sheet post-processing apparatus according to claim 1, wherein,
when the number of sheets conveyed to the processing tray exceeds
the predetermined number, the control unit increases, in aligning
the sheet conveyed thereto last, the amount of movement of the
first aligning plate or the second aligning plate to be larger than
the amount of movement at the number of sheets equal to or smaller
than the predetermined number.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a Division of application Ser. No.
12/885,771 filed on Sep. 20, 2010, which is a Continuation of
application Ser. No. 11/681,523 filed on Mar. 2, 2007, the entire
contents of both of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a sheet post-processing
apparatus including a sheet aligning device that aligns sheets
conveyed thereto in the case of staple processing and the like.
[0004] 2. Description of the Related Art
[0005] When sheets subjected to image formation in an image forming
apparatus is received and post-process processing such as staple
processing and punching processing is performed in a sheet
post-processing apparatus that applies post-processing, it is
necessary to align the sheets prior to this post-process
processing.
[0006] Conventionally, a first aligning plate and a second aligning
plate that nip a bundle of sheets are provided, the first aligning
plate and the second aligning plate are moved in a direction of the
bundle of sheets, one of the aligning plates is provisionally
fixed, and the other aligning plate is further moved in the
direction of the bundle of sheets to perform alignment in a
horizontal direction. A rotor having a paddle is rotated to bring
the paddle into contact with the sheets conveyed thereto and the
sheets are drawn in by the paddle and struck against a stopper to
perform alignment in a vertical direction. (For example,
JP-A-2006-124156).
[0007] However, when the number of sheets increases, the sheets
less easily move to a side and alignment cannot be performed
satisfactorily. If a force for moving the aligning plates is
increased, when there are few sheets, the sheets bend and alignment
of the sheets is disordered. In this way, in the conventional sheet
aligning device, since only one kind of setting for an aligning
operation can be performed, there is a problem in that it is
difficult to set the aligning operation to appropriately perform
alignment of sheets even when there are few sheets or many
sheets.
BRIEF SUMMARY OF THE INVENTION
[0008] It is an object of the present invention to provide a sheet
post-processing apparatus including a sheet aligning device that
increases, when the number of sheets conveyed thereto exceeds a
predetermined number, the number of times of an aligning operation
of the sheet aligning device to be larger than the number of times
of an aligning operation at the number of sheets equal to or
smaller than the predetermined number of sheets.
[0009] In an aspect of the present invention, a sheet
post-processing apparatus includes a processing tray that receives
sheets subjected to image formation from an image forming
apparatus, a sheet discharge tray that stacks the sheets discharged
after processing in a post process, and a sheet aligning device
having a vertical aligning device that aligns the sheets conveyed
to the processing tray in a conveying direction, a horizontal
aligning device that aligns the sheets conveyed to the processing
tray in a direction perpendicular to the conveying direction, and a
control unit that controls aligning operations of the vertical
aligning device and the horizontal aligning device and increases,
in subjecting the sheets to staple processing, when the number of
the sheets conveyed thereto exceeds a predetermined number, the
number of times of the aligning operation of the vertical aligning
device or the horizontal aligning device to be larger than the
number of times of the aligning operation at the number of sheets
equal to or smaller than the predetermined number of sheets.
DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 is a schematic diagram of a structure concerning
control of a sheet aligning device;
[0011] FIG. 2 is a perspective view of a vertical aligning
device;
[0012] FIG. 3 is a diagram of the vertical aligning device viewed
from the side;
[0013] FIG. 4 is a perspective view of a horizontal aligning
device;
[0014] FIG. 5 is a perspective view in the case in which the
vertical aligning device and the horizontal aligning device are
built in a sheet post-processing apparatus;
[0015] FIG. 6 is a perspective view in the case in which the
vertical aligning device and the horizontal aligning device are
built in the sheet post-processing apparatus;
[0016] FIG. 7 is a schematic diagram showing the sheet
post-processing apparatus in which the sheet aligning device is
set;
[0017] FIG. 8A is a timing chart of a horizontal alignment L motor,
which moves a first aligning plate, and a horizontal alignment L
home position sensor;
[0018] FIG. 8B is a timing chart of a horizontal alignment R motor,
which moves a second aligning plate, and a horizontal alignment R
home position sensor;
[0019] FIG. 9A is a timing chart of the vertical aligning device in
the case in which the number of sheets conveyed thereto is equal to
or smaller than a predetermined number; and
[0020] FIG. 9B is a timing chart of the vertical aligning device in
the case in which the number of sheets conveyed thereto exceeds the
predetermined number.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Throughout this description, the embodiments and examples
shown should be considered as exemplars, rather than limitations on
the apparatus and methods of the present invention.
[0022] An embodiment of the invention will be hereinafter explained
using the drawings. In the respective figures, identical components
are denoted by identical reference numerals and signs and redundant
explanations are omitted.
[0023] A sheet post-processing apparatus performs, for example,
staple processing, punching processing, and folding processing as
processing of a post process of an image forming apparatus. In that
case, since it is necessary to align sheets subjected to image
formation, i.e., align vertical and horizontal sides of the sheets,
a sheet aligning device is provided in the sheet post-processing
apparatus.
[0024] FIG. 1 is a schematic diagram of a structure concerning
control of the sheet aligning device built in the sheet
post-processing apparatus according to this embodiment. A sheet
aligning device 80 includes a vertical aligning device 81 that
aligns sheets conveyed to the sheet aligning device 80 in a
conveying direction, a horizontal aligning device 82 that aligns
the sheets conveyed thereto in a direction perpendicular to the
conveying direction, and a control unit 83 that controls aligning
operations of the vertical aligning device 81 and the horizontal
aligning device 82.
[0025] This control unit 83 may be independently provided for
exclusive use of the sheet aligning device 80, may be provided as a
part of a control unit of the sheet post-processing apparatus
integrated with the sheet aligning device 80, or may be provided as
apart of a control unit of an image forming apparatus with which
the sheet post-processing apparatus is provided in parallel. When
the control unit 83 is independently provided, the control unit 83
includes a CPU or a processor, a memory, a storage device, and a
communicating device.
[0026] The control unit 83 is connected to a number-of-sheet
counter 90 that counts the number of sheets conveyed to the sheet
aligning device 80. The number-of-sheet counter 90 may be provided
in the sheet post-processing apparatus integrated with the sheet
aligning device 80 or maybe provided in an image forming apparatus
in which the sheet post-processing apparatus is set. The
number-of-sheet counter 90 may be provided for exclusive use of the
sheet aligning device 80. In this case, the number-of-sheet counter
90 may have an interface for transmitting and receiving data to and
from a sheet sensor and the control unit 83.
[0027] The control unit 83 is connected to a paddle motor 46 of the
vertical aligning device 81, which is a motor that rotates a paddle
that aligns sheets in a conveying direction, a home position sensor
85 that detects a home position of the paddle, a horizontal
alignment L roller 86 that moves a first aligning plate of the
horizontal aligning device 82, a horizontal alignment L home
position sensor 87 that detects a home position of the first
aligning plate, a horizontal alignment R motor 48 that moves a
second aligning plate of the horizontal aligning device 82, and a
horizontal alignment R home position sensor 89 that detects a home
position of the second aligning plate.
[0028] In this embodiment, two motors, namely, the horizontal
alignment L motor 86 and the horizontal alignment R motor 48 are
used in the horizontal aligning device 82. However, the respective
aligning plates may be moved by one motor.
[0029] FIG. 2 is a perspective view of the vertical aligning device
81 according to this embodiment. The vertical aligning device 81
includes a paddle 44 provided radially with respect to a rotation
axis in a rotor, a paddle motor 46 that rotates this rotor, a
stopper 45 against which a leading end of sheets is struck to align
the sheets, and a not-shown home position sensor 85. When the sheet
aligning devices are set in the sheet post-processing apparatus, a
conveyor belt 50 that conveys aligned sheets to a processing tray
in order to perform processing such as stapling may be
provided.
[0030] FIG. 3 is a diagram of the vertical aligning device 81
viewed from the side. Sheets are conveyed in an arrow q direction.
The paddle 44 is provided in the rotor to be radial in three
directions. The paddle 44 has a receiving unit 44a, a tapping unit
446 that taps down the sheets, and a sending unit 44c that aligns
the sheets. The paddle 44 is driven by the paddle motor 46. The
paddle 44 is formed of resin having elasticity. When sheets are
conveyed thereto, the paddles 44a, 44b, and 44c rotate in a
direction of an arrow o, come into contact with the sheets, tap
down the sheets, draw the sheets into the stopper 45, and strike
the sheets against the stopper 45 to align the sheets in the sheet
conveying direction.
[0031] FIG. 4 is a perspective view of the horizontal aligning
device 82. The horizontal aligning device 82 includes a first
aligning plate 47b, a second aligning plate 47a, a horizontal
alignment L motor 86 and a horizontal alignment L home position
sensor 87, which are not shown in the figure, a horizontal
alignment R motor 48, and a not-shown horizontal alignment R home
position sensor 89.
[0032] The first aligning plate 47b and the second aligning plate
47a reciprocatingly move in a direction of an arrow v perpendicular
to the conveying direction of the sheets. The sheets conveyed to
the horizontal aligning device 82 are guided to a space between the
first aligning plate 47b and the second aligning plate 47a. The
respective aligning plates nip the sheets to align the sheets in
the conveying direction and the vertical direction. A damper is
provided in the first aligning plate 47b. The damper may be a
damper of a spring type or may be a damper formed of resin or the
like having flexibility.
[0033] In this embodiment, a device including a rotor with paddle
and a stopper is adopted as the vertical aligning device 81. A
device including two aligning plates is adopted as the horizontal
aligning device 82. However, sheet aligning devices including
mechanisms different from these may be adopted for the vertical
aligning device 81 and the horizontal aligning device 82.
[0034] FIGS. 5 and 6 are perspective views in the case in which the
vertical aligning device 81 and the horizontal aligning device 82
according to this embodiment are built in the sheet post-processing
apparatus. FIG. 7 is a schematic diagram showing a sheet
post-processing apparatus 7, in which the sheet aligning device 80
according to this embodiment is set, arranged adjacent to an image
forming apparatus 5 such as a copying machine. This sheet
post-processing apparatus 7 basically includes a standby tray 10, a
processing tray 12, a stapler 14, a first sheet discharge tray 16,
and a second sheet discharge tray 18. In FIGS. 5 to 7, the vertical
aligning device 81 and the horizontal aligning device 82 according
to this embodiment are set in the processing tray 12.
[0035] Sheets P subjected to image formation in the image forming
apparatus 5 such as a copying machine and discharged from a pair of
sheet discharge rollers 6 are received by a pair of entrance
rollers 22, supplied to a pair of sheet feeding rollers 24, and
sent from the sheet feeding rollers 24 to the standby tray 10. The
entrance rollers 22 are driven by an entrance roller motor 26. A
paper path ceiling 36 that guides the sheets P to the sheet feeding
rollers 24 is provided between the entrance rollers 22 and the
standby tray 10. The entrance rollers 22 include an upper entrance
roller 22a and a lower entrance roller 22b. The sheet feeding
rollers 24 also include an upper sheet feeding roller and a lower
sheet feeding roller.
[0036] The processing tray 12 that stacks the sheets P dropped and
supplied from the standby tray 10 is arranged below the standby
tray 10.
[0037] The processing tray 12 aligns and supports the sheets P
stacked while the sheets P are subjected to staple processing by
the stapler 14 serving as a processing mechanism for performing the
post-processing. In a position where a trailing end of the sheets P
fall when the sheets P are dropped and supplied to the processing
tray 12, the vertical aligning device 81 having the rotatable
paddle 44 for aligning the top sheet P placed on the processing
tray 12 is arranged.
[0038] As shown in FIG. 7, the standby tray 10 is capable of
dropping and supplying the sheets P to the processing tray 12 and,
on the other hand, is capable of conveying the sheets P in a
direction of the first or the second sheet discharge tray 16 or 18.
The conveyance of the sheets P in the direction of the sheet
discharge tray 16 or 18 is performed by bringing the standby tray
roller 28, which performs alignment of the sheets P, into contact
with the sheets P on the standby tray 10. Up and down movements of
the standby tray roller 28 are controlled by a standby tray roller
driving source 30.
[0039] The standby tray 10 is arranged at an inclination angle
.theta.1 in order to support the sheets P in a state in which a
leading end of the sheets P is higher than a trailing end thereof.
The first or the second sheet discharge tray 16 or 18 is lifted and
lowered by a sheet-discharge-tray driving unit 52 and selected. The
first or the second sheet discharge tray 16 or 18 is lifted to
height substantially the same as the height of the standby tray 10
or the processing tray 12 during stacking of the sheets P to
realize improvement of alignability of the sheets P discharged. The
first or the second sheet discharge tray 16 or 18 is arranged at an
inclination angle .theta.2 in order to support the sheets P in a
state in which the leading end of the sheets P is higher than the
trailing end of thereof.
[0040] FIGS. 8A and 8B are timing charts of the horizontal aligning
device 81 according to this embodiment. FIG. 8A is a timing chart
of the horizontal alignment L motor 86, which moves the first
aligning plate 47b, and the horizontal alignment L home position
sensor 87. FIG. 8B is a timing chart of the horizontal alignment R
motor 48, which moves the second aligning plate 47a, and the
horizontal alignment R home position sensor 89.
[0041] When sheets conveyed to the horizontal aligning device 81 is
equal to or smaller than a predetermined number, alignment is
performed as follows. Before the sheets are conveyed, the
respective aligning plates are located in a home position. The
control unit 83 moves the first aligning plate 47b and the second
aligning plate 47a located in a home position 61 to a standby
position 62, which corresponds to the width of the sheets conveyed
thereto, by rotating the horizontal alignment L motor 86 and the
horizontal alignment R motor 48 in a regular rotation direction.
The sheets conveyed thereto are guided to a space between the first
aligning plate 47b and the second aligning plate 47a.
[0042] When the conveyance of the sheets is finished, the control
unit 83 rotates the horizontal alignment L motor 86 and the
horizontal alignment R motor 48 in the regular rotation direction
to perform a driving operation for moving the first aligning plate
47b and the second aligning plate 47a to an alignment position 63
and aligns the sheets in a direction perpendicular to the conveying
direction. The driving means aligning the sheets with an interval
between the first aligning plate 47b and the second aligning plate
47a set narrower than a width in a horizontal alignment direction
of the sheets to be aligned.
[0043] It is desirable that an amount of movement of the first
aligning plate 47b and the second aligning plate 47a in the driving
operation of this first alignment operation, i.e., a driving amount
is, for example, equal to or larger than 0.9 mm and equal to or
smaller than 2 mm. When the driving amount is smaller than this,
alignment is insufficient and, when the driving amount is larger
than this, since sheets bend, alignment is disarranged.
[0044] The driving operation may be performed every time one sheet
is conveyed or may be performed only once when all the sheets are
finished to be conveyed. If the driving operation is performed only
once when all the sheets are finished to be conveyed, it is
possible to minimize an increase in a processing time.
[0045] When stepping motors are used as the horizontal alignment L
motor 86 and the horizontal alignment R motor 87, the control of
the driving amount is performed by controlling the number of steps.
When DC motors are used as the horizontal alignment L motor 86 and
the horizontal alignment R motor 87, the control of the driving
amount is performed by controlling driving times of the respective
motors. In this embodiment, it is assumed that the stepping motors
are used.
[0046] When the number of sheets conveyed thereto exceeds the
predetermined number, alignment is performed as follows. The
control unit 83 receives information on the number of sheets from
the number-of-sheet counter 90 and determines whether this number
of sheets has exceeded the predetermined number. When the number of
sheets has exceeded the predetermined number, the control unit 83
increases the driving amount to be larger than a driving amount at
the time when the number of sheets is equal to or smaller than the
predetermined number.
[0047] For example, the control unit 83 increases the driving
amount to be about twice as large as that in the case in which the
number of sheets is equal to or smaller than the predetermined
number, for example, increases the driving amount from 0.8 mm or
more to 4 mm or less. If the driving amount is smaller than this,
since a bundle of sheets stacked is thick, alignment is
insufficient. When the driving amount is larger than this, since
the sheets bend, alignment is disarranged. It is suitable that this
driving amount is set according to the number of sheets to be
aligned.
[0048] In the driving operation, when the thickness of a sheet
bundle to be aligned is small, sturdiness of the sheet bundle is
low. When the thickness of the sheet bundle is large, sturdiness of
the sheet bundle is high. In this way, since the sturdiness changes
according to the thickness of the bundle of sheets to be aligned,
it is suitable that the driving amount is set according to the
sturdiness of the bundle of sheets to be aligned.
[0049] The control unit 83 increases the number of times of the
aligning operation of the horizontal aligning device 81.
Specifically, the control unit 83 fixes the second aligning plate
47a, rotates the horizontal alignment L motor 86 in the regular
rotation direction in a predetermined number of steps to press and
align the sheets with the first aligning plate 47b, and
subsequently rotates the horizontal alignment L motor 86 in a
reverse rotation direction in the predetermined number of steps to
separate the first aligning plate 47b from the sheets.
[0050] A combination of the pressing and the separating operations
is performed, for example, twice. It is suitable that the number of
times the combination is performed is increased or decreased
according to the number of sheets to be aligned. This second
aligning operation is performed after the first aligning operation.
Before the second aligning operation is performed, the first
aligning plate 47b may be returned to the standby position 62.
[0051] This second aligning operation may be performed every time a
sheet is conveyed or may be performed when all the sheets are
finished to be conveyed. Also, it may be performed every time the
number of sheets exceeds the predetermined number. When the second
aligning operation is performed when all the sheets are finished to
be conveyed, it is possible to minimize an increase in a processing
time.
[0052] Moreover, the control unit 83 increases the number of times
of the aligning operation of the vertical aligning device 81. FIGS.
9A and 9B are timing charts of the vertical aligning device 81.
[0053] FIG. 9A is a timing chart of the vertical aligning device 81
in the case in which the number of sheets conveyed to the vertical
aligning device 81 is equal to or smaller than the predetermined
number. The paddle 44 of the vertical aligning device 81 is located
in a home position until the sheets are conveyed thereto. When the
sheets are conveyed thereto, the control unit 83 rotates the paddle
motor 46 in a regular rotation direction to rotate the paddle 44
twice and, after that, reversely rotates the paddle motor 46 to
return the paddle 44 to the home position.
[0054] FIG. 9B is a timing chart of the vertical aligning device 81
in the case in which the number of sheets conveyed to the vertical
aligning device 81 exceeds the predetermined number. When the
number of sheets conveyed thereto exceeds the predetermined number,
the control unit 83 increases the number of times of alignment of
the vertical aligning device 81. Specifically, the control unit 83
performs an aligning operation as follows. The paddle 44 of the
vertical aligning device 81 is located in the home position before
the sheets are conveyed thereto. When the sheets are conveyed
thereto, the control unit 83 rotates the paddle motor 46 in the
regular rotation direction to rotate the paddle 44 three times,
which is one time more than that in the case in which the number of
sheets conveyed thereto is equal to or smaller than the
predetermined number, and, after that, reversely rotates the paddle
motor 46 to return the paddle 44 to the home position.
[0055] In this way, in this embodiment, the paddle 44 is rotated
three times when the number of sheets conveyed to the vertical
aligning device 81 exceeds the predetermined number. However, the
paddle 44 may be rotated four or more times. This aligning
operation with the increased number of rotations may be performed
every time a sheet is conveyed thereto or may be applied to only a
last sheet conveyed thereto. When the aligning operation with the
number of rotations increased is applied, to only the last sheet
conveyed thereto, it is possible to minimize an increase in a
processing time.
[0056] The predetermined number of the number of sheets conveyed
thereto forming a reference for increasing the number of times of
the aligning operation or the driving amount may be set for each
sheet size or each thickness of sheets. A default value of the
predetermined number may be set and the user may be able to change
the default value as appropriate. As an example of this
predetermined number, it is possible to set the predetermined
number to twenty. However, it is possible to set this number
arbitrarily.
[0057] Moreover, it is also possible to increase the number of
times of the aligning operation or the driving amount when the
thickness of a sheet bundle exceeds a predetermined thickness. In
this case, the thickness of a sheet bundle, the thickness of
sheets, and the number of conveyed sheets forming references for
increasing the number of times of the aligning operation or the
driving amount are inputted to the control unit 83. It is possible
to input the thickness of a sheet bundle and the thickness of
sheets from, for example, an input device such as a touch panel
provided in the sheet post-processing apparatus 7 or the image
forming apparatus 5.
[0058] It is possible to input the thickness of a sheet bundle as a
numerical value, for example, 10 mm. It is possible to input the
thickness of sheets as a numerical value, for example, 30 g/m.sup.2
or by selecting a type of sheets such as "thick", "standard", or
"thin". The control unit 83 calculates the number of sheets forming
a reference for increasing the number of times of the aligning
operation or the driving amount according to calculation from these
numerical values inputted or by reading a conversion table provided
in advance for converting the thickness of a sheet bundle and the
thickness of sheets into the number of sheets. When the number of
sheets conveyed to the vertical aligning device 81 exceeds the
number of sheets forming the reference, the control unit 83
determines that the sheet bundle has exceeded the predetermined
thickness and increase the number of times of the aligning
operation or the driving amount.
[0059] Operations of the sheet post-processing apparatus according
to this embodiment integrated with the sheet aligning device 80
will be explained using FIG. 7. When the sheets P are subjected to
image formation in the image forming apparatus 5 and supplied from
sheet discharging rollers 6, the sheet post-processing apparatus 7
performs different kinds of operation depending on whether the
post-processing for the sheets P is performed or not performed or
whether the post-processing for the preceding sheets P is being
executed or the post-processing has been finished.
[0060] When the post-processing is not performed, for example, the
first sheet discharge tray 16 has slid to a position indicated by a
dotted line in FIG. 7 and is capable of stacking, with high
alignability, the sheets P discharged from the standby tray 10.
When the post-processing is not performed, the sheets P conveyed
from the entrance rollers 22 to the sheet feeding rollers 24 via
the paper path ceiling 36 are fed to the standby tray 10 by the
sheet feeding roller 24. Subsequently, the sheets P are lowered
onto the standby tray 10, conveyed by the standby tray roller 28
rotated in an arrow f direction, and discharged to the first sheet
discharge tray 16.
[0061] In this way, sheets are sequentially stacked on the first
sheet discharge tray 16. The first sheet discharge tray 16 is
arranged to have an inclination angle .theta.2 and a leading end of
the sheets is higher than a trailing end of the sheets. Thus, for
example, even if the sheets P are discharged onto the first sheet
discharge tray 16 in a state in which the sheets P are curled as
indicated by a dotted line in FIG. 9, the sheets P placed on the
first sheet discharge tray 16 earlier are not pushed out by contact
with the leading end of the following sheet P. In other words, the
discharged sheets P are sequentially placed on the sheet discharge
tray 16 in order without being disordered. Even if the preceding
sheets P are pushed by the following sheet P and some positional
shift is caused, since the first sheet discharge tray 16 has the
inclination angle .theta.2, the sheets P fall because of their own
weight and are aligned and stacked in a state in which the trailing
end thereof is even on the first sheet discharge tray 16.
[0062] When sheets subjected to image formation in the image
forming apparatus 5 are received and the post-processing such as
stapling and sorting is not performed, the sheet discharge tray 16
or 18 does not perform any up and down operation at all until
sheets discharged from the sheet post-processing apparatus 7 reach
a predetermined number. It is possible to count the number of
discharged sheets with, for example, a sheet upper surface
detecting sensor (not shown) that detects an upper surface of
sheets.
[0063] When sheets stacked on the sheet discharge tray 16 or 18
reach the predetermined number, the sheet discharge tray 16 or 18
perform the up and down operation and a sheet trailing end is
prevented from remaining in the sheet discharge port (not shown) of
the sheet post-processing apparatus 7 to perform accurate upper
surface detection.
[0064] It is suitable that, after the sheets reach the
predetermined number, a standstill state of the sheet discharge
tray 16 or 18 is maintained until the sheet upper surface detecting
sensor is in the ON state for a predetermined time or more, for
example, 5 msec or more. This is because, in general, presence of a
dead zone is inevitable in actuators of various sensors and the
like.
[0065] Here, the upper surface of the sheets is detected in order
to manage the number of sheets on the sheet discharge tray 16 or 18
not to exceed a stackable number of sheets thereof and grasp a
present movable position of the sheet discharge tray 16 or 18.
[0066] The set number of sheets described above may be set as, for
example, forty as a default at the time of shipment of the sheet
post-processing apparatus 7 or a user may be able to set the number
of sheets.
[0067] A stroke amount of the up and down operation of the sheet
discharge tray 16 or 18 is set to at least about 50 mm. This is
because, when the stroke amount is too small, hooking at the sheet
trailing end cannot be released. On the other hand, when the stroke
amount is too large, the up and down operation of the sheet
discharge tray 16 or 18 takes time and productivity is
deteriorated.
[0068] The stroke amount of the up and down operation of the sheet
discharge tray 16 or 18 may be set as a default at the time of
shipment of the sheet post-processing apparatus 7 or the user may
be able to set the stroke amount.
[0069] It is suitable that the up and down operation of the sheet
discharge tray 16 or 18 is faster at the time of lowering than at
the time of lifting. This is because sheets fall to the sheet
discharge tray 16 or 18 faster.
[0070] A case in which the staple processing as the post-processing
is performed and there is no sheets P, for which the staple
processing is being executed earlier, on the processing tray 20
will be described.
[0071] In this case, the standby tray 10 drops and supplies the
sheet P onto the processing tray 12. As shown in FIG. 7, in order
to align the horizontal direction of the sheet P, the horizontal
aligning plates 47a and 47b are arranged such that an interval
between the horizontal aligning plates 47a and 47b are
substantially the same as the width of the sheet P. Consequently,
the sheet P fed by the sheet feeding rollers 24 is dropped and
supplied onto the processing tray 12 through the standby tray
10.
[0072] During the drop and supply, the upper vertical aligning
roller 38a is retracted upward and the receiving unit 44a of the
paddle 44 receives the trailing end of the sheet P. Both the sides
of the sheet P fall while being in contact with the first aligning
plate 47b and the second aligning plate 47a of the horizontal
aligning device 82, the sheet P is aligned in the horizontal
direction, and the aligning operation in the horizontal direction
is performed.
[0073] The paddle 44 of the vertical aligning device 81 rotates in
an arrow o direction, drops the trailing end of the sheet P from
the receiving unit 44a, and taps down the sheet P onto the
processing tray 12 with the tapping unit 44b. Moreover, the paddle
44 sends the sheet P in an arrow q direction with the sending unit
44c, brings the trailing end of the sheet P into contact with the
stopper 45, and completes the alignment in the vertical direction
of the sheet P. Details of the aligning operation in the vertical
direction are as described above.
[0074] In this way, the sheets P subjected to image formation are
stacked on the processing tray 12 from the sheet feeding rollers 24
through the standby tray 10 while being sequentially aligned in the
horizontal direction and the vertical direction. When the sheets P
reach the predetermined number, the stapler 14 staples the sheets P
on the processing tray 12 in a desired position in a bundle to form
the sheet bundle T. Thereafter, the upper vertical aligning roller
38a is lowered onto the sheet bundle. The sheet bundle T is held by
the upper vertical aligning roller 38a rotating in an arrow r
direction and the lower vertical aligning roller 38b rotating in an
arrow s direction to be conveyed ma direction of the first sheet
discharge tray 16.
[0075] When the trailing end of the sheet bundle T passes the upper
and the lower vertical aligning rollers 38a and 38b, the trailing
end is hooked by the sending pawl 50a of the conveyor belt 50
rotated in an arrow t direction and discharged onto the first sheet
discharge tray 16.
[0076] At this point, the first sheet discharge tray 16 is slid
from the position indicated by the dotted line to a position
indicated by a solid line in FIG. 7. Since the first sheet
discharge tray 16 is arranged to have the inclination angle
.theta.2 and the sheet leading end is higher than the trailing end,
the sheets P discharged onto the first sheet discharge tray 16
earlier are not pushed out because of contact with the leading end
of the following sheet bundle T. Even if the preceding sheet bundle
T is pushed by the following sheet P and some positional shift is
caused, since the first sheet discharge tray 16 has the inclination
angle .theta.2, the sheet bundle T falls because of its own weight
and is aligned and stacked in a state in which the trailing end
thereof is even on the first sheet discharge tray 16. The staple
processing for the sheets P is completed.
[0077] A case in which the staple processing as the post-processing
is performed and the sheets P, for which the staple processing is
being executed earlier, remain in the processing tray 20 will be
described.
[0078] In this case, the standby tray 10 is capable of supporting
the sheets P. The standby tray roller 28 is retracted to above the
standby tray 10 not to hinder the sheets P. The sheets P discharged
from the image forming apparatus 5 and supplied by the sheet
feeding rollers 24 are temporarily placed on the standby tray 10 in
order to wait for the processing tray 12 to be empty.
[0079] The sheets P placed on the standby tray 10 is vertically
aligned by the standby tray roller 28 rotated in a direction
opposite to the arrow f direction. Moreover, since the standby tray
10 is arranged to have the inclination angle .theta.1 and the sheet
leading end is higher than the trailing end, the sheets P are
vertically aligned by their own weights as well.
[0080] Since the standby tray 10 is arranged to have the
inclination angle .theta.1, for example, even if the sheets P are
supplied from the sheet feeding rollers 24 and fed onto the standby
tray 10 in a state in which the sheets P are curled, the sheets P
placed on the standby tray 10 earlier are not pushed out by contact
with the leading end of the following sheet P. In other words, the
supplied sheets P are placed on the standby tray 10 in order
without being disordered. Even if the preceding sheets P are pushed
by the following sheet P and some positional shift is caused, since
the standby tray 10 has the inclination angle .theta.1, the sheets
P fall because of their own weight and are aligned and stacked in a
state in which the trailing end thereof is even on the standby tray
10.
[0081] When the preceding sheets P on the processing tray 12 are
discharged to the first sheet discharge tray 16 side and the
processing tray 12 is emptied, the standby tray 10 drops and
supplies the sheets P onto the processing tray 12. At this point,
the first aligning plate 47b and the second aligning plate 47a of
the horizontal aligning device 82 are arranged such that an
interval between the aligning plates is substantially the same as
the width of the sheets P. Therefore, both the sides of the sheets
P dropped from the standby tray 10 are regulated by the respective
horizontal aligning plates 47a and 47b, the horizontal direction of
the sheets P is aligned, and the aligning operation in the
horizontal direction is performed.
[0082] The sheet P on the lower side of the two sheets P dropped to
the processing tray 12 is sent in the arrow q direction by the
lower vertical aligning roller 38b rotated in the direction
opposite to the arrows direction, the trailing end of the sheet P
is brought into contact with the stopper 45, and the alignment in
the vertical direction of the sheet P is completed. The sheet P on
the upper side of the two sheets P dropped to the processing tray
12 is sent in the arrow q direction by the upper vertical aligning
roller 38a rotated in the direction opposite to the arrow r
direction, the trailing end of the sheet P is brought into contact
with the stopper 45, and the alignment in the vertical direction of
the sheet P is completed. Thereafter, the upper vertical aligning
roller 38a is retracted upward. Details of the aligning operation
in the vertical direction are as described above.
[0083] The third and subsequent sheets P discharged from the image
forming apparatus 5 are directly dropped and supplied to the
processing tray 12 without being put on standby on the standby tray
10. Thereafter, the third and subsequent sheets Pare sequentially
aligned on the sheets P.sub.r which are stacked on the processing
tray 12 earlier, by the paddle 44 of the vertical aligning device
81.
[0084] When the sheets P stacked on the processing tray 12 reach
the predetermined number, the sheets P are subjected to the staple
processing by the stapler 14 to form the sheet bundle T.
Thereafter, the sheet bundle T is conveyed in the direction of the
first sheet discharge tray 16 by the upper and the lower vertical
aligning rollers 38a and 38b, the trailing end of the sheet bundle
T is hooked by the sending pawl 50a of the conveyor belt 50, the
sheet bundle T is discharged onto the first sheet discharge tray
16, and the staple processing for the sheets P is completed.
[0085] The image forming apparatus including the sheet
post-processing apparatus integrated with the sheet aligning device
BO according to this embodiment will be explained. As shown in FIG.
7, this sheet post-processing apparatus 7 is installed adjacent to
the image forming apparatus 5. Sheets subjected to image formation
by the image forming apparatus 5 are discharged from the sheet
discharging rollers 6 and supplied to the sheet post-processing
apparatus 7 from the entrance rollers 22 of the sheet
post-processing apparatus 7.
[0086] As described above, in the sheet post-processing apparatus 7
according to this embodiment, in the case of staple processing,
when the number of sheets conveyed to the sheet aligning device 80
exceeds the predetermined number, the sheet aligning device 80
increases the number of times of the aligning operation of the
vertical aligning device 81 and the number of times of the aligning
operation of the horizontal aligning device 82 to be larger than
the number of times of the aligning operation at the number of
sheets equal to or smaller than the predetermined number. The sheet
aligning device 80 increases the driving amount of the horizontal
aligning device 82 to be larger than the driving amount at the
number of sheets equal to or smaller than the predetermined number.
Therefore, even when the number of sheets conveyed to the sheet
aligning device 80 is small or large, the sheet aligning device 80
can perform appropriate alignment processing and the sheet
post-processing apparatus 7 can appropriately perform staple
processing.
[0087] It is possible to minimize an increase in a processing time
by performing the aligning operation with the number of times or
the driving amount increased when all the sheets are conveyed.
[0088] Since it is possible to appropriately set the number of
times of the aligning operation of the vertical aligning device 81
and the number of times of aligning operation and the driving
amount of the horizontal aligning device 82 according to the number
of sheets to be aligned, a size of the sheets, or the thickness of
the sheets, it is possible to perform an aligning operation
suitable for sturdiness of a sheet bundle to be aligned and perform
appropriate alignment processing.
[0089] When the control unit 83 receives, from an external counter,
information on the number of sheets conveyed to the sheet aligning
device 80, since it is unnecessary to provide an apparatus such as
a sensor that counts the number of sheets, it is possible to hold
down manufacturing cost.
[0090] 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 alterations to the invention as described herein may be made,
none of which depart from the spirit of the present invention. All
such changes, modifications, and alterations should therefore be
seen as within the scope of the present invention.
* * * * *