U.S. patent application number 12/042475 was filed with the patent office on 2008-12-25 for sheet post-processing apparatus and sheet post-processing method.
This patent application is currently assigned to KABUSHIKI KAISHA TOSHIBA. Invention is credited to Yasunobu Terao, Mikio Yamamoto.
Application Number | 20080315494 12/042475 |
Document ID | / |
Family ID | 40135675 |
Filed Date | 2008-12-25 |
United States Patent
Application |
20080315494 |
Kind Code |
A1 |
Terao; Yasunobu ; et
al. |
December 25, 2008 |
SHEET POST-PROCESSING APPARATUS AND SHEET POST-PROCESSING
METHOD
Abstract
In a sheet post-processing apparatus, a sheet guide is arranged
above a processing tray that aligns stacked one or plural sheets.
The sheet guide is moved by racks to be spaced apart from or
brought close to the processing tray. The racks are controlled to
be driven on the basis of the number of sheets stacked on the
processing tray or the thickness of a stack of the sheets to adjust
a space between the processing tray and the sheet guide.
Inventors: |
Terao; Yasunobu;
(Izunokuni-shi, JP) ; Yamamoto; Mikio;
(Izunokuni-shi, JP) |
Correspondence
Address: |
AMIN, TUROCY & CALVIN, LLP
127 Public Square, 57th Floor, Key Tower
CLEVELAND
OH
44114
US
|
Assignee: |
KABUSHIKI KAISHA TOSHIBA
Tokyo
JP
TOSHIBA TEC KABUSHIKI KAISHA
Tokyo
JP
|
Family ID: |
40135675 |
Appl. No.: |
12/042475 |
Filed: |
March 5, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60944820 |
Jun 19, 2007 |
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60944824 |
Jun 19, 2007 |
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60944825 |
Jun 19, 2007 |
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Current U.S.
Class: |
270/58.12 ;
270/58.01; 270/58.27 |
Current CPC
Class: |
B65H 2301/4212 20130101;
B65H 31/02 20130101; B65H 31/3081 20130101; B65H 2511/152 20130101;
B65H 29/52 20130101; B65H 2301/4213 20130101; B65H 2511/415
20130101; B65H 2511/20 20130101; B65H 2220/02 20130101; B65H
2511/415 20130101; B65H 2511/152 20130101; B65H 2220/01 20130101;
B65H 2220/01 20130101; B65H 2407/10 20130101; B65H 2801/27
20130101; B65H 2405/11151 20130101; B65H 2511/20 20130101 |
Class at
Publication: |
270/58.12 ;
270/58.27; 270/58.01 |
International
Class: |
B65H 39/00 20060101
B65H039/00 |
Claims
1. A sheet post-processing apparatus comprising: a processing tray
that aligns stacked one or plural sheets; a sheet guide arranged
above the processing tray; a sheet guide driving mechanism that
moves the sheet guide to be spaced apart from or brought close to
the processing tray; and a driving control mechanism that controls
to drive the sheet guide driving mechanism on the basis of a number
of sheets stacked on the processing tray or thickness of a stack of
the sheets and adjusts a space between the processing tray and the
sheet guide.
2. A sheet post-processing apparatus according to claim 1, wherein
the driving control mechanism includes means for controlling to
drive the sheet guide driving mechanism to adjust the space every
time the number of sheets stacked on the processing tray increases
by a predetermined number or predetermined thickness.
3. A sheet post-processing apparatus according to claim 1, wherein
the driving control mechanism includes means for controlling the
sheet guide driving mechanism to adjust the space every time the
number of sheets stacked on the processing tray increases by
one.
4. A sheet post-processing apparatus according to claim 1, wherein
the sheet post-processing apparatus is an apparatus that
post-processes a sheet after image processing fed from an image
forming apparatus, and the driving control mechanism includes means
for controlling to drive the sheet guide driving mechanism to
adjust the space on the basis of any one of a number of processed
sheets fed from the image forming apparatus and thickness of the
sheets or both.
5. A sheet post-processing apparatus according to claim 1, wherein
the sheet post-processing apparatus includes detecting means for
detecting a space between a ceiling surface of the sheet guide and
a lower surface of the processing tray or an upper surface of
sheets stacked on the processing tray, and the driving control
mechanism includes means for adjusting the space on the basis of a
value of the space detected by the detecting means.
6. A sheet post-processing apparatus according to claim 1, wherein
the sheet guide driving mechanism includes a rack attached to the
sheet guide, a pinion that meshes with the rack, and a motor that
drives the pinion.
7. A sheet post-processing apparatus according to claim 1, wherein
a stapler is arranged on a rear side of the processing tray and a
stacking tray is arranged on a front side of the processing tray,
and the processing tray includes a rear end stopper that positions
a rear end of a sheet, a discharge roller that discharges the sheet
stacked on the processing tray to a stacking tray, and a horizontal
aligning mechanism and a vertical aligning mechanism for the
sheet.
8. A sheet post-processing apparatus according to claim 7, wherein
the processing tray includes an ejector that pushes out the sheet
stacked on the processing tray in a direction of the stacking tray
and a pushing member that pushes a lower surface of a trailing end
of the sheet fed from the processing tray.
9. A sheet post-processing apparatus comprising: means for aligning
stacked one or plural sheets; means for guiding a sheet arranged
above the aligning means; sheet guide driving means for moving the
sheet guiding means to be spaced apart from or brought close to the
aligning means; and driving control means for controlling to drive
the sheet guide driving means on the basis of a number of sheets
stacked on the aligning means or thickness of a stack of the sheets
and adjusting a space between the aligning means and the sheet
guiding means.
10. A sheet post-processing method comprising: stacking one or
plural sheets on a processing tray and aligning the sheets; moving
a sheet guide arranged above the processing tray to be spaced apart
from or brought close to the processing tray using a sheet guide
driving mechanism; and controlling to drive the sheet guide driving
mechanism on the basis of a number of sheets stacked on the
processing tray or thickness of a stack of the sheets and adjusting
a space between the processing tray and the sheet guide driving
mechanism.
11. A sheet post-processing method according to claim 10, wherein,
when the sheets M in the processing tray are subjected to
post-processing, a standby tray 10 puts sheets M, which are
conveyed thereto and form a sheet stack for subsequent
post-processing, on a standby tray and keeps the sheets M in a
standby state, so as to secure a post-processing time.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Applications No. 60/944,820, filed Jun. 19, 2007; No. 60/944,824,
filed Jun. 19, 2007; and No. 60/944,825, filed Jun. 19, 2007.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a sheet post-processing
apparatus with an improved sheet guide and a sheet post-processing
method.
[0004] 2. Description of the Related Art
[0005] A sheet post-processing apparatus is an apparatus that
stacks plural sheets on a processing tray and, after aligning these
sheets, performs post processing such as staple processing and sort
processing of the sheets, and discharges a processed sheet bundle
to a stacking tray after the post processing.
[0006] The sheet post-processing apparatus includes a sheet guide
above the processing tray. However, the sheet guide is fixed in a
predetermined position. A space between an upper surface of the
processing tray and a ceiling surface of the sheet guide is fixed
regardless of the number of sheets stacked on the processing tray.
Therefore, for example, if this space is increased to make it
possible to stack a bundle of about one-hundred sheets, the sheets
may not be able to be stably guided because the space is increased
to be too large and some of the sheets may curl when the sheets are
about to be stacked on the processing guide. As a result, sheet
aligning properties are poor and it is likely that a deficiency
occurs in the staple processing and the like. Moreover, when the
space is set wide in this way, human fingertips reach the inside of
a stapler through the space between the processing tray and the
sheet guide, it is likely that an accident occurs.
[0007] On the other hand, when the space is reduced to prevent the
human fingertips from reaching the inside of the stapler, only a
small number of sheets can be stacked on the processing tray. As a
result, the number of sheets that can be stapled is limited.
[0008] Japanese Patent Disclosure (Kokai) No. 2003-212419; Y.
Nakayama et al.; Jul. 30, 2003 discloses a technique for forming a
gap between a pressing member 58a and the surface of an aligning
tray 41. Since the gap is formed between the pressing member 58a
and the surface of the aligning tray 41, when a sheet is conveyed,
the pressing member 58a does not prevent the conveyance of the
sheet and the sheet can be smoothly conveyed.
BRIEF SUMMARY OF THE INVENTION
[0009] The present invention provides a sheet post-processing
apparatus and a sheet post-processing method for not limiting the
number of sheets stacked on a processing tray and preventing human
fingers from entering a stapler from a space between the processing
tray and a sheet guide.
[0010] In order to solve the problem, a sheet post-processing
apparatus according to an aspect of the present invention is a
sheet post-processing apparatus including:
[0011] a processing tray that aligns stacked one or plural
sheets;
[0012] a sheet guide arranged above the processing tray;
[0013] a sheet guide driving mechanism that moves the sheet guide
to be spaced apart from or brought close to the processing tray;
and
[0014] a driving control mechanism that controls to drive the sheet
guide driving mechanism on the basis of the number of sheets
stacked on the processing tray or the thickness of a stack of the
sheets and adjusts a space between the processing tray and the
sheet guide.
[0015] According to an aspect of the present invention, the sheet
guide can move from a position close to the processing tray to a
position away from the processing tray. Therefore, it is possible
to always keep a space between the processing tray and the sheet
guide small and prevent human fingers from entering the stapler by
mistake to improve safety of the sheet post-processing apparatus.
It is also possible to prevent a sheet from curling.
[0016] Further, the sheet guide is gradually moved in a direction
away from the processing tray to secure a predetermined space
between the processing tray and the sheet guide. Therefore, even
when a large number of sheets are processed, it is possible to
appropriately stack the sheets.
[0017] When a small number of sheets are processed, it is
unnecessary to move the sheet guide while maintaining a
predetermined small space between the processing tray and the sheet
guide. Therefore, operability of the sheet post-processing
apparatus is improved.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0018] FIG. 1 is a schematic diagram of a digital copying machine
(an image forming apparatus) and a post-processing apparatus
according to an embodiment of the present invention connected to
the image forming apparatus;
[0019] FIG. 2 is a diagram of a processing tray according to the
embodiment viewed from obliquely above;
[0020] FIG. 3 is a diagram for explaining an ejector and a bar-like
pushing member in the processing tray and members related to these
members;
[0021] FIG. 4 is a diagram for explaining a bundle claw belt in the
post-processing apparatus and members related to the bundle claw
belt;
[0022] FIG. 5 is a diagram showing a form of a bundle claw for
conveying a sheet bundle stacked on the processing tray to a
stacking tray;
[0023] FIG. 6 is an enlarged schematic diagram of a sheet guide of
the post-processing apparatus and a driving mechanism therefor;
[0024] FIG. 7 is a diagram for explaining a driving control
mechanism;
[0025] FIG. 8 is a diagram of a processing tray according to
another embodiment of the present invention viewed from obliquely
above;
[0026] FIG. 9 is a diagram showing another form of the bundle claw
for conveying a sheet bundle stacked on the processing tray to the
stacking tray;
[0027] FIG. 10 is a diagram showing still another form of bundle
claw for conveying a sheet bundle stacked on the processing tray to
the stacking tray;
[0028] FIG. 11 is a diagram for explaining actions of the sheet
guide and the driving mechanism therefor and shows a state in which
no sheet is stacked on the processing tray;
[0029] FIG. 12 is a diagram for explaining actions of the sheet
guide and the driving mechanism therefor and shows a state in which
sheets are stacked on the processing tray (about fifty sheets with
the thickness of about 7 mm);
[0030] FIG. 13 is a diagram for explaining actions of the sheet
guide and the driving mechanism therefor and shows a state in which
sheets are stacked on the processing tray and the sheet guide is
moved upward (about fifty sheets; about 7 mm thick);
[0031] FIG. 14 is a diagram for explaining actions of the sheet
guide and the driving mechanism therefor and shows a state in which
sheets are further stacked on the processing tray (about 100
sheets) after the sheet guide is moved upward;
[0032] FIG. 15 shows a process of conveying a sheet stacked on the
processing tray to the stacking tray using a conveying mechanism
according to the embodiment and shows a state before a lower
surface of a leading end of the sheet is pushed by pushing
members;
[0033] FIG. 16 shows a process of conveying a sheet stacked on the
processing tray to the stacking tray using the conveying mechanism
according to the embodiment and shows a state in which the lower
surface of the leading end of the sheet is pushed by the pushing
members; and
[0034] FIG. 17 shows a process of conveying a sheet stacked on the
processing tray to the stacking tray using the conveying mechanism
according to the embodiment and shows a state after the lower
surface of the leading end of the sheet is pushed by the pushing
members.
DETAILED DESCRIPTION OF THE INVENTION
[0035] Embodiments of the present invention will be hereinafter
explained in detail with reference to the accompanying
drawings.
(Overview of an Image forming Apparatus)
[0036] An overview of an image forming apparatus (a digital copying
machine) and a post-processing apparatus according to an embodiment
of the present invention arranged to be connected to a post-stage
of the image forming apparatus are explained with reference to FIG.
1. In the image forming apparatus, an original placing stand 112 is
provided on an upper surface thereof. An automatic document feeder
107 (hereinafter referred to as ADF) that automatically feeds an
original D onto the original placing stand 112 is arranged on the
original placing stand 112. After placing the original D on the ADF
and performing predetermined setting (e.g., presence or absence of
staple processing, a way of the staple processing, the number of
copies, and a size of a sheet to be copied), a user presses a copy
start switch. The original D on the ADF is conveyed to a
predetermined position of the original placing stand 112.
[0037] A scanner unit 104, a printer unit 106, and cassettes 152,
153, 154, and 156 and a feeder 155 for copy sheets P are disposed
inside the image forming apparatus. The scanner unit 104 scans the
original D on the original placing stand 112, makes reflected light
of the original D incident thereon, photoelectrically converts the
incident reflected light to the read image information of the
original D, and outputs a photoelectric signal corresponding to the
read image information. The printer unit 106 forms an electrostatic
latent image on a circumferential surface of a photoconductive drum
144 using a semiconductor laser 141 according to the image
information and the like of the original D read by the scanner unit
104. A developing device 146 supplies a toner to the
photoconductive drum 144 and visualizes the electrostatic latent
image formed on the photoconductive drum 144 to form a toner
image.
[0038] The copy sheets P are fed to the photoconductive drum 144
from the cassettes 152, 153, 154, and 156 and the feeder 155 for
the copy sheets P. The toner image on the photoconductive drum 144
is copied onto each of the copy sheets P by a transfer charger 148.
Thereafter, the toner image on the copy sheet P is fixed by a
fixing device 160 and the copy sheet P is discharged from a
discharge opening 161. The copy sheet P is equivalent to a sheet M
according to the embodiment.
(Overview of the Post-Processing Apparatus)
[0039] The post-processing apparatus 1 arranged to be connected to
the post stage of the digital copying machine includes a standby
tray 10 that accumulates several sheets M fed through an entrance
roller 2 and an exit roller 4 and puts the sheets M on standby, a
processing tray 12 that receives the sheets M dropped from the
standby tray 10 and aligns trailing ends of the sheets M for staple
processing, a stapler (stapling means) 14 that subjects the
trailing ends of the sheets M accumulated in the processing tray 12
and aligned to staple processing (binding processing), a conveying
mechanism 50 that conveys the sheets M after being subjected to the
staple processing, sort processing, and the like, and a stacking
tray 16 (18) on which the conveyed sheets M are stacked.
[0040] When the sheets M in the processing tray 12 are subjected to
the staple processing, the standby tray 10 puts sheets M, which are
conveyed thereto and form the next sheet stack for subsequent
post-processing, in a place separate from the processing tray 12
and temporarily keeps the sheets M in a standby state. In this
manner, the processing tray 12 secures a time the stapler 14
requires for the staple processing.
[0041] The standby tray 10, the processing tray 12, and the
stacking tray 16 (18) are provided to incline downward to trailing
ends in a feeding direction of the sheets M. A sheet guide 19 is
arranged above the processing tray 12 to be spaced apart from the
processing tray 12 and guides the sheets M fed to the processing
tray 12. The stapler 14 is arranged at the trailing end in the
feeding direction of the sheets M of the processing tray 12, stops
the sheets M, which are placed on the processing tray 12, on the
trailing end side, and performs the staple processing for the
sheets M.
(Processing Tray)
[0042] FIG. 2 is a diagram of the processing tray 12 viewed from
obliquely above. The processing tray 12 has a flat sheet support
surface 12a on which the sheets M dropped from the standby tray 10
are placed and accumulated. In the processing tray 12, horizontal
alignment plates 20 for horizontally aligning the sheets M are
provided on both sides in a width direction of the sheet support
surface 12a. Further, in the processing tray 12, trailing end
stoppers 22 are provided on a trailing end side in a conveying
direction of the sheet support surface 12a to project from a
trailing end surface of the sheet support surface 12a. Moreover, in
the processing tray 12, vertical alignment rollers 24 are provided
on the trailing end side in the conveying direction. A paddle 26
(shown in FIGS. 1, 15, 16, and 17) is provided on the trailing end
side in the conveying direction above the processing tray 12. The
sheets M received in the processing tray 12 are brought into
contact with the trailing end stoppers 22 and vertically aligned by
the paddle 26, the vertical alignment rollers 24, and discharge
rollers 28a, 28b, 28c, and 28d.
[0043] Four discharge rollers 28a, 28b, 28c, and 28d in total are
provided on a leading end side in the conveying direction of the
sheet support surface 12a of the processing tray 12. Two of the
discharge rollers are provided in the center and the other two are
provided on both sides of the sheet support surface 12a,
respectively. These discharge rollers are driven to rotate to
convey the sheets M to the stacking tray 16 (18).
[0044] In the center on the trailing end side of the sheet support
surface 12a of the processing tray 12, ejectors 30 are provided to
project from the trailing end surface of the processing tray 12. In
the center on the leading end side of the sheet support surface 12a
of the processing tray 12, bar-like pushing members 32 are
arranged. Distal end portions of the pushing members are located
between the discharge rollers 28c and 28d in the center. The
pushing members 32 are made of, for example, an elastic plate
material or a composite member formed by laminating an elastic
plate material and a plastic plate material and are integrally
attached to the ejectors 30, respectively.
[0045] The pushing members 32 are formed of flexible plastic that
can be elastically deformed even by a touch of a hand. Frictional
members (e.g., rubber) are provided on distal end upper surfaces
thereof. The pushing members 32 do not usually project from the
processing tray 12 and are in positions further retracted than the
discharge rollers 28a, 28b, 28c, and 28d. Therefore, the pushing
members 32 do not come into contact with the sheet M. When the
pushing members 32 project from the leading end side in the
conveying direction of the sheet support surface 12a of the
processing tray 12, the frictional members on the leading end upper
surfaces come into contact with the lower surface of the sheet M
and push up the lower surface of the sheet M.
[0046] The ejectors 30 and the pushing members 32 integrally
attached to the ejectors 30 are driven by an identical motor to
perform a reciprocating action of moving in the direction of the
stacking tray 16 and returning from the movement. The ejectors 30
and the pushing members 32 move at the same timing and in the same
distance. FIG. 3 shows the elector 30, the pushing member 32, a
belt 34 that supports the ejector 30 and the pushing member 32,
pulleys 36 around which the belt 34 is wound, and a motor 38 that
drives the pulleys 36. Driving control of the motor 38 is performed
by a driving control mechanism 60 described later. Driving of the
pushing member 32 can be performed not only by the motor 38 but
also by a solenoid (a rotary solenoid).
[0047] A bundle claw belt 40 is arranged between a pair of ejectors
30 and between a pair of pushing members 32. As shown in FIG. 4,
the bundle claw belt 40 is attached with a bundle claw 41 and wound
between the pulleys 42. An upper surface of the bundle claw belt 40
moves in a sheet conveying direction. The pulleys 42 are driven by
a motor 44. Driving control of the motor 44 is performed by the
driving control mechanism 60 described later.
[0048] In the bundle claw 41 attached to the bundle claw belt 40,
as shown in FIG. 5, a concave portion 46 for regulating a position
of a sheet trailing end is formed. The concave portion 46 has a
bottom surface with which the sheet trailing end comes into
contact. In the bottom surface, a surface 48a on a lower side that
is in contact with the bundle claw belt 40 is formed to be
depressed deeper than a surface 48b on an upper side. A step
portion 48c is formed between the surface 48a on the lower side and
the surface 48b on the upper side.
[0049] FIG. 6 is a schematic diagram for explaining, in particular,
the sheet guide 19 and members related to thereto in the processing
tray 12. The sheet guide 19 formed of a metal plate material, a
resin molding, or the like is provided above the processing tray
12. A rack 52 is attached to the sheet guide 19. The rack 52 meshes
with a pinion 54, which is driven by a motor 56. Therefore, when
the motor 56 is driven, the sheet guide 19 moves in a direction
away from the processing tray 12 or a direction toward the
processing tray 12. The motor 56 is controlled by the driving
control mechanism 60.
(Driving Control)
[0050] In the image forming apparatus, as described above, the
predetermined setting (e.g., setting of presence or absence of
staple processing, a way of the staple processing, the number of
copies, and a size of a sheet to be copied) is performed.
Therefore, as shown in FIG. 7, the driving control mechanism 60 is
inputted with information concerning any one of the number of
sheets and the thickness of the sheets or both from the image
forming apparatus and controls the driving of the motor 56 on the
basis of a signal of this input and the number of sheets stacked on
the processing tray 12. Alternatively, the driving control
mechanism 60 detects, using space detecting means 62 (shown in FIG.
6) mounted on the processing tray 12, a space between a ceiling
surface of the sheet guide 19 and an upper surface of sheets
stacked on the processing tray 12 (when sheets are not stacked, an
upper surface of the processing tray 12) (equivalent to the
thickness of stacked sheets) and controls the driving of the motor
56 on the basis of a value of this detection. The driving of the
motor 56 may be continuously performed every time sheets are
increased or may be intermittently performed to reduce the space
between the sheet guide 19 and the upper surface of sheets to be
equal to or smaller than about 7 mm when a space between the sheet
M and the sheet guide 19 is reduced by some degree. When aligned
sheets are fed to the stacking tray 16 and it is detected that the
sheets M are not stacked on the processing tray 12, the driving
control mechanism 60 drives the motor 56 and resets the sheet guide
19 to an initially set position. In this position, a space small
enough for preventing human fingers from entering is provided
between the processing tray 12 and the sheet guide 19. It is
possible to guide a small number of sheets.
[0051] In conveying a sheet stacked on the processing tray 12 to
the stacking tray 16, the driving control mechanism 60 performs
control of the driving motor 38 that drives the ejector 30 and the
pushing member 32, the motor 44 that drives the bundle claw belt
40, and the like. For example, when staple processing in the
stapler 14 is finished, the driving control mechanism 60 sends a
driving signal to the motor 38, moves the ejector 30 and the
pushing member 32 in the direction of the stacking tray 16, and,
after moving the ejector 30 and the pushing member 32 by a
predetermined stroke, returns the same to original positions
thereof. The driving control mechanism 60 sends a driving signal to
the motor 44 at appropriate timing and moves the bundle claw 41 of
the bundle claw belt 40 in the direction of the stacking tray 16.
The appropriate timing is timing when a trailing end of the sheet
fed by the ejector 30 can be received by the bundle claw 41.
Other Embodiments
[0052] In the example shown in FIG. 2, the pair of pushing members
32 are provided on outer sides of the bundle claw belt 40 provided
between the discharge rollers 28c and 28d in the center. However,
the present invention is not limited to this. For example, as shown
in FIG. 8, another pair of pushing members may be provided on outer
sides of the discharge rollers 28c and 28d in the center together
with the pushing members 32 in FIG. 2 to arrange two pairs of
pushing materials in total. In the structure shown in FIG. 8, the
added pushing members are not attached to the ejectors 30. The
added pushing members may reciprocatingly move in synchronization
with the ejectors 30 shown in FIG. 2 or may reciprocatingly move at
timing shifted from that of the ejectors 30 shown in FIG. 2. A
range in which the added pushing members move may be the same as or
different from a range in which the pushing members 32 shown in
FIG. 2 move. A driving source of the added pushing members may be
the same as or different from a driving source of the ejectors 30
shown in FIG. 2.
[0053] In FIG. 5, the concave portion 46 of the bundle claw 41 is
integrally formed. However, the present invention is not limited to
this. For example, as shown in FIG. 9, a member 48d having
predetermined thickness may be stuck to a surface on an upper side
of the concave portion 46 to form the step portion 48c between the
surface 48a on the lower side and the surface 48b on the upper
side. In this case, the bundle claw 41 can be manufactured by
directly using a bundle claw having a flat bottom surface
publicly-known in the past.
[0054] In the bundle claw 41 shown in FIGS. 5 and 9, both the
surface 48a on the lower side and the surface 48b on the upper side
are planes. However, as shown in FIG. 10, these surfaces can be
surfaces bent convexly. With this bundle claw, even when a sheet
tilts in a plan view with respect to a conveying direction thereof
(i.e., when a trailing end surface of the sheet is not set at an
angle of 90.degree. with respect to the conveying direction), it is
possible to surely regulate a position of the sheet trailing
end.
(Explanation of Operations)
(Staple Mode)
[0055] Operations of the post-processing apparatus at the time of a
staple mode are explained.
[0056] The sheet M is fed from the image forming apparatus to the
post-processing apparatus (see an arrow direction in FIG. 1). The
post-processing apparatus receives the sheet M in the entrance
roller 2 and conveys the sheet M to the exit roller 4. When the
sheets M exist in the processing tray 12, the post-processing
apparatus temporarily stores the sheet M conveyed from the exit
roller 4 in the standby tray 10. Subsequently, the post-processing
apparatus opens the standby tray 10 and drops and supplies the
stored sheet M to the processing tray 12. When the sheets M do not
exist in the processing tray 12, the post-processing apparatus
drops and supplies the sheet M to the processing tray without
temporarily storing the sheet M in the standby tray 10.
[0057] The processing tray 12 horizontally aligns the sheet M using
the horizontal alignment plates 20 and bumps a trailing end of the
sheet M against the trailing end stoppers 22 and vertically aligns
the sheet M using the paddle 26 and the vertical alignment rollers
24. In this way, the sheet M is vertically and horizontally aligned
by the processing tray 12 and guided by the sheet guide 19 and the
processing tray 12. The sheet trailing end is guided into the
stapler 14. The operation is sequentially applied to the sheets M
fed one after another to guide the respective sheets M into the
stapler 14.
[0058] The sheet guide 19 is initially set at a space with which
sheets up to a specified number of sheets, for example, about fifty
sheets (about 7 mm thick) can be guided.
[0059] FIG. 11 shows a state in which no sheet is stacked on the
processing tray 12. FIG. 12 shows a state in which the specified
number of sheets M, e.g., about fifty sheets (about 7 mm thick) are
stacked on the processing tray 12.
[0060] When sheets M are increased and exceed the specified number,
the sheet guide 19 is moved upward to increase the space between
the sheet guide 19 and the processing tray 12. FIG. 13 shows a
state in which the sheet guide 19 is moved upward to increase the
space and can guide up to about one-hundred sheets.
[0061] FIG. 14 shows a state in which a sheet M of a last page
(e.g., one-hundredth sheet) is stacked on the processing tray 12.
After aligning the last page (e.g., one-hundredth sheet), the
sheets M are stapled by the stapler 14.
[0062] A stapled sheet bundle is pushed out by the ejector 10 and
passed to the bundle claw 41 of the bundle claw belt 40. The bundle
claw 41 discharges the sheets M to the stacking tray 16 in
cooperation with the discharge rollers 28a, 28b, 28c, and 28d.
(Sort Mode)
[0063] Operations of the post-processing apparatus at the time of a
sort mode are explained.
[0064] The sheet M is fed from the image forming apparatus to the
post-processing apparatus (see the arrow direction in FIG. 1). The
post-processing apparatus receives the sheet M in the entrance
roller 2 and conveys the sheet M to the exit roller 4. The
post-processing apparatus temporarily stores the sheet M conveyed
from the exit roller 4 in the standby tray 10. Subsequently, the
post-processing apparatus opens the standby tray 10 and drops and
supplies the stored sheet M to the processing tray 12. The sheet
guide 19 and the processing tray 12 guide the sheet M and guide the
trailing end of the sheet M into the stapler 14. The processing
tray 12 bumps the trailing end of the sheet M against the trailing
end stoppers 22 using the paddle 26, the horizontal alignment
plates 20, and the vertical alignment rollers 24 and sorts the
sheet M using the horizontal alignment plates 20 simultaneously
with the alignment (e.g., shifts the sheet M by 15 mm). The sheet M
is pushed out by the ejectors 30 and passed to the bundle claw 41
of the bundle claw belt 40. The bundle claw 41 discharges the
sheets M to the stacking tray 16 in cooperation with the discharge
rollers 28a, 28b, 28c, and 28d.
[0065] In the case of sort, the number of sheets to be discharged
(the number of sheets stacked on the processing tray 12) is divided
into small numbers of sheets (about one to four sheets).
[0066] With the post-processing apparatus, it is possible to set a
guide space according to sheet thickness and it is unlikely that
human fingers enter the stapler by mistake. If there is information
concerning the thickness of sheets, it is possible to control the
space by detecting the number of sheets to be conveyed. Moreover,
when a smaller number of sheets are processed, it is unnecessary to
move the sheet guide 19 up and down while keeping the space set
small. Therefore, it is possible to perform processing safely, at
high speed, and with controlled noise occurrence.
(Sheet Conveyance)
[0067] In order to realize the compact structure of the
post-processing apparatus, the processing tray 12 and the stacking
tray 16 are arranged close to each other. Therefore, the leading
end of the sheet M stacked on the processing tray 12 is in contact
with the stacking tray 16 (see FIG. 15).
[0068] When the sheet M is conveyed from the processing tray 12 to
the stacking tray 16, first, the ejectors 30 are driven and moved
in the direction of the stacking tray 16. Although a position of
the trailing end of the sheet M is regulated by the trailing end
stoppers 22, the trailing end of the sheet M is caught by the
ejectors 30 to move the sheet M in the direction of the stacking
tray 16. At this point, the leading end of the sheet M is in
contact with the upper surface of the stacking tray 16 or an upper
surface of sheets already stacked on the stacking tray 16 and
static friction occurs between the sheet and the stacking tray 16.
Since a coefficient of static friction is larger than a coefficient
of dynamic friction, the leading end of the sheet M in contact with
the stacking tray 16 hardly moves. On the other hand, other
portions of the sheet M move. As a result, the center of the sheet
M starts to bend upward (see FIGS. 15 and 16).
[0069] In the post-processing apparatus, the pushing members 32
move in the direction of the stacking tray 16 in synchronization
with the ejectors 30. Therefore, simultaneously with the movement
of the sheet M by the ejectors 30, a lower surface of the leading
end of the sheet M is pushed to relax and reduce a contact force
between the lower surface of the leading end of the sheet M and the
stacking tray 16 (or the upper surface of the sheets already
stacked on the stacking tray 16). As a result, static friction at
the leading end of the sheet M is changed to dynamic friction and
the entire sheet is conveyed to the stacking tray 16 without
curling (see FIGS. 16 and 17). The sheet M is aligned and stacked
on the stacking tray 16.
[0070] If the lower surface of the leading end of the sheet M is
not pushed by the pushing members 32, since the sheet M is fed to
the stacking tray 16 while bending upward, the sheet M is stacked
on the stacking tray 16 in a nonaligned state. When stacked plural
sheets are conveyed, a leading end of sheets on a lower side hang
down (curl to the lower side) unless the leading end is supported
by the processing tray 12. When the sheets are conveyed in this
state, the sheets on the lower side among the plural sheets are
stacked on the stacking tray 16 in a state in which the leading end
side thereof is bent inward. With the post-processing apparatus, it
is possible to prevent such an unfavorable stacking state.
[0071] When the sheets are aligned, the pushing members 32 are
located lower than the discharge rollers and do not come into
contact with the sheets. After the lower surface of the leading end
of the sheets is pushed, since the pushing members 32 return to
original positions thereof (positions lower than the discharge
rollers), when the sheets are conveyed by the bundle claw 41, the
pushing members 32 do not come into contact with the sheets.
Therefore, the sheets can be discharged to the stacking tray 16
without a trailing end of the sheet bundle being caught by the
pushing members 32.
[0072] As described above, with the post-processing apparatus, even
if the leading end of the sheet M comes into contact with the
stacking tray 16, since the leading end of the sheet M is pushed by
the pushing members 32 to relax and reduce a contact force between
the stacking tray 16 and the leading end of the sheet, it is
possible to prevent the sheet M from bending during conveyance.
Therefore, it is possible to appropriately convey even a shin sheet
and stacked plural sheets to the stacking tray 16. When the sheet M
is pushed by the pushing members 32, conveyance of the sheet M is
supported. Therefore, directional properties in conveying the sheet
M to the stacking tray 16 are stabilized and stacking alignment
properties in the stacking tray 16 are improved.
[0073] Further, by integrating the pushing members 32 with the
ejectors 30, it is possible to reduce component cost, provide a
common driving source for reciprocating movements of the pushing
members 32 and the ejectors 30, and reduce sources of occurrence of
noise.
[0074] Actions of the bundle claw belt 40 in feeding the sheet M to
the stacking tray 16 are explained.
[0075] The ejectors 30 push the trailing end of the sheet M in the
direction of the stacking tray 16 in a predetermined range. The
sheet M pushed out a predetermined distance by the ejectors 30 is
passed to the bundle claw 41 attached to the bundle claw belt 40.
When the number of sheets is small, the trailing end of the sheets
comes into contact with the surface 48a on the lower side of the
bundle claw 41 (see FIGS. 5 and 9) and movement of the sheets to
the surface on the upper side is regulated by the step portion 48c.
As a result, it is possible to fix conveying speed of the sheets
and control fluctuation in a conveying distance to thereby align
and stack the sheets on the stacking tray 16.
[0076] Usually, the height of the bundle claw 41 is set large to
make it possible to discharge a stapled bundle of one-hundred or
more sheets. However, if the bottom surface of the concave portion
46 that regulates the trailing end of the sheet M is flat, in the
case of a small number of sheets, the trailing end of the sheets
cannot be fixed to a position on the lower surface side of the
concave surface of the bundle claw 41 and slides to the upper
surface side. The bundle claw belt 40 moves in the direction of the
stacking tray 16 on the processing tray 12. However, at a point
when the trailing end of the sheets is discharged from the bundle
claw belt 40, the bundle claw belt 40 rotates. At this point, if
the trailing end of the sheets is located on the lower surface side
of the concave surface of the bundle claw 41, where the trailing
end of the sheets should be originally located, since the position
is a position close to a rotation center of the bundle claw belt
40, speed of discharging the sheets does not change. However, when
the trailing end of the sheets moves to the upper surface side of
the concave surface of the bundle claw 41, since the trailing end
of the sheets is located apart from the rotation center, speed of
discharging the sheets increases. As a result, discharge speed
fluctuates and the sheets are stacked on the stacking tray 16 in a
nonaligned state.
[0077] In the post-processing apparatus, when a small number of
sheets are discharged from the processing tray 12 to the stacking
tray 16, the trailing end of the sheets is located on the lower
surface side of the concave surface of the bundle claw 41, where
the trailing end of the sheets should be originally located, and
does not move to the upper surface side of the concave surface of
the bundle claw 41. As a result, fluctuation in discharge speed of
the sheets is reduced and it is possible to stably discharge the
sheets.
* * * * *