US20080315490A1

US20080315490A1 - Sheet stacking apparatus and sheet processing apparatus equipped therewith

Info

Publication number: US20080315490A1
Application number: US11/945,444
Authority: US
Inventors: Masaaki Uchiyama; Hiroyuki Wakabayashi
Original assignee: Konica Minolta Business Technologies Inc
Current assignee: Konica Minolta Business Technologies Inc
Priority date: 2007-06-21
Filing date: 2007-11-27
Publication date: 2008-12-25

Abstract

A sheet stacking apparatus includes: a stacking tray which stacks a fold-processed and ejected sheet, and descends in response to a mass of stacked sheets; and a first sheet pressing member which holds the stacked sheets downward from an upper side of the stacked sheets at a constant height.

Description

This application is based on Japanese Patent Application Nos. 2007-163536 filed on Jun. 21, 2007, 2007-164803 filed on Jun. 22, 2007, and 2007-164804 filed on Jun. 22, 2007, which are incorporated hereinto by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a sheet processing apparatus for conducting a fold processing of a sheet, particularly, relates to an improvement of a sheet ejection section in a small size sheet processing apparatus for conducting the fold processing of a sheet, onto which an image has been formed, by combining an image forming apparatus.
With respect to the ejection section in the image forming apparatus and a sheet processing apparatus, the improvement of stacking sheets onto a stacking tray in the sheet ejection sections of the image forming apparatus in perfect order has been conducted.
The fold-processed sheet tends to become irregular and tends to be irregularly stacked in the sheet ejection section comparing with a flat shaped sheet, to which the fold process has not been applied.
Particularly, in the case of the sheets, to which a multiple-fold such as three-fold has been applied, for example, the sheets, to which the multiple-fold such as a gatefold or a double-parallel fold has been applied, there is a case that the sheets are deformed into a completely different style from a flat plate shape, stacked irregularly in the stacking section and scattered out from the stacking section.
Hitherto, the fold-processed sheets have only been stacked into a box shaped tray. The sheets have been irregularly stacked into the stacking tray.
Unexamined Japanese Patent Application Publication Nos. 2002-255431 and 2001-26360 disclose technologies for putting the fold-processed sheets in order.
According to the technology disclosed in Unexamined Japanese Patent Application Publication No. 2002-255431, a roller provided at the edge of the arm, which is capable of freely rotating, and a paddle, which is capable of freely rotating, hold two points of the sheets to be stacked in order to stack the fold-processed sheets onto the stacking tray.
According to the technology disclosed in Unexamined Japanese Patent Application Publication No. 2002-26360, a sensor is arranged to detect the uppermost surface of stacked sheets and to lower the stacking tray when the uppermost surface rises.
In the case of the technology disclosed in Unexamined Japanese Patent Application Publication No. 2002-255431, since both of the two holding members move up and down, the sheets cannot be stacked in perfect order in the sheet stacking operation where the sheets tend to bulge and the uppermost surface of the sheet to be stacked is able to move up and down just like a fold-processed sheet.
Further, the stacking apparatus disclosed in Unexamined Japanese Patent Application Publication No. 2002-255431 does not have a moving mechanism of the stacking tray corresponding to a stacking amount. Thus the stacking apparatus in Unexamined Japanese Patent Application Publication No. 2002-255431 is not suitable for stacking a large volume of sheets.
According to the technology disclosed in Unexamined Japanese Patent Application Publication No. 2001-26360, it allows the stacking tray to stack a large volume of sheets by lowering and raising the stacking tray by utilizing a motor drive.
According to the mechanism for lowering and raising the stacking tray by a motor drive, which has been disclosed in Unexamined Japanese Patent Application Publication No. 2001-26360, a sensor detects the uppermost surface of the sheets and the detected signal controls the motor.
According to the control described above, in the case of stacking the fold-processed sheets, there is a problem that erroneous operations tend to occur due to sheet bulge. Also there is a problem that lack of stability and reliability of the operation occurs.
Further, there is a problem that the motor drive makes a control mechanism complicated and raises the cost of the apparatus.
Unexamined Japanese Patent Application Publication Nos. 2002-274727 and 07-300270 disclose a technology for proving a sheet pressing member for pressing sheets downward to a place adjacent to an ejection section.
Unexamined Japanese Patent Application Publication No. 07-300270 discloses a sheet presser operating member for drawing a sheet pressing member and moving the sheet pressing member onto the upper surface of a newly ejected sheet.
According to Unexamined Japanese Patent Application Publication Nos. 2002-274727 and 07-300270, the structure is not arranged to put the fold-processed sheets in order. The structure is not well designed to stack the sheets in order to stack the fold-processed sheets in order.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, a sheet stacking apparatus includes
a stacking tray for stacking a fold-processed and ejected sheet, the stacking tray being arranged to descend corresponding to a mass of stacked sheets, and
a first sheet pressing member for pressing the stacked sheets from an upper side of the stacked sheets at a constant height.
According to another aspect of the present invention, a sheet stacking apparatus includes
a stacking tray for stacking a fold-processed and ejected sheet,
a first sheet pressing member for pressing a trailing edge of a sheet in an ejection direction of the sheet at a constant height, and
a second sheet pressing member for pressing a leading edge of the sheet on the stacking tray in the ejection direction of the sheet,
wherein the second sheet pressing member is supported by a stationary section in an upstream side edge of the sheet in the ejection direction of the sheet and a downstream side edge portion of the second sheet pressing member in the ejection direction of the sheet is a free edge.
According to still another aspect of the present invention, a sheet stacking apparatus for stacking a fold-processed and ejected sheet includes
a sheet stacking tray for stacking a sheet
a third sheet pressing member for holding a sheet, which has been stacked on the stacking tray, and
a control member for controlling the third sheet pressing member,
wherein the control member selectively positions the third sheet pressing member at either a place where the third sheet pressing member presses the sheet or a retreated place where the third sheet pressing member has retreated from the sheet in response to at least one of a sheet size, a sheet kind, and a kind of fold processing.
According to yet still another aspect of the present invention, a sheet stacking apparatus including a fold processing section for conducting a fold processing of a sheet, an ejection section for ejecting a fold-processed sheet and a sheet stacking apparatus for stacking the sheet, which has been ejected from the ejection section, the sheet stacking apparatus includes,
a stacking tray, which is capable of descending in response to a mass of stacked sheets, to which the fold process has been applied and ejected from the ejection section, and
a sheet pressing member for pressing the stacked sheets from an upper side of the stacked sheet at a constant height.
According to yet still another aspect of the present invention, a sheet processing apparatus including a fold processing section for conducting a fold processing of a sheet, ejection rollers structured by a pair of rollers, an ejection section for ejecting a sheet processed by the fold processing section, and
a sheet stacking apparatus for stacking a sheet ejected from the ejection section, the sheet processing apparatus includes,
a stacking tray for stacking a sheet, to which the fold process has been applied by the fold processing section and ejected from the ejection section,
a first sheet pressing member for pressing a trailing edge of the sheet in an ejection direction of the sheet at a constant height, and
a second sheet pressing member for pressing a leading edge of the sheet on the stacking tray in the ejection direction of the sheet,
wherein the second sheet pressing member is supported by a stationary shaft section in an upstream side edge portion of the sheet in an ejection direction of the sheet and a downstream side edge portion of the second sheet pressing member in the ejection direction of the sheet is a free edge.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a total drawing of an image forming system having a sheet processing apparatus related to an embodiment of the present invention.

FIG. 2 illustrates a total structure drawing of a sheet processing apparatus B of the present invention.

FIGS. 3( a)-3(f) illustrate examples of fold processes.

FIG. 4 illustrates a cross sectional view of a sheet stacking apparatus related to an embodiment of the present invention.

FIG. 5 illustrates a cross sectional view of a sheet stacking apparatus related to an embodiment of the present invention.

FIG. 6 illustrates a perspective view of a sheet stacking apparatus related to an embodiment of the present invention.

FIG. 7 illustrates a relationship between ejection rollers and a rotary member of the sheet processing apparatus.

FIG. 8 illustrates a cross sectional view of the sheet stacking apparatus related to the other embodiment of the present invention.

FIG. 9 illustrates a cross sectional view of the sheet stacking apparatus related to the other embodiment of the present invention.

FIG. 10 illustrates a perspective view of the sheet stacking apparatus related to the other embodiment of the present invention.

FIG. 11 illustrates a relationship between ejection rollers and a rotary member of the sheet processing apparatus.

FIG. 12 illustrates a cross sectional view of the sheet stacking apparatus related to the other embodiment of the present invention.

FIG. 13 illustrates a cross sectional view of the sheet stacking apparatus related to the other embodiment of the present invention.

FIG. 14 illustrates a perspective view of the sheet stacking apparatus related to the other embodiment of the present invention.

FIG. 15 illustrates a relationship between ejection rollers and a rotary member of the sheet processing apparatus.

FIG. 16 illustrates a cross sectional view of the sheet stacking apparatus related to the other embodiment of the present invention.

FIG. 17 illustrates a plan view of the sheet stacking apparatus related to the other embodiment of the present invention.

FIG. 18 illustrates a block diagram of a control system of an image forming system having a sheet processing apparatus related to an embodiment of the present invention.

FIG. 19 illustrates a flowchart for a control of a sheet pressing member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will be described by using embodiments of the present invention. However, the present invention is not limited to the embodiments.
FIG. 1 illustrates the total drawing of the image forming system having a sheet processing apparatus pertaining to an embodiment of the present invention.

[Image Forming System]

An image forming system includes an image forming apparatus A, an automatic document feeder DF, a sheet processing apparatus B and a large capacity tray LT.
An image forming apparatus A illustrated in FIG. 1 includes an image reading section (an image input apparatus) 1, an image processing section 2, an image writing section 3, an image forming section 4, a sheet feed cassettes 5A, 5B and 5C, a manual feed tray 5D, a first sheet feed sections 6A, 6B, 6C, 6D and 6E, a second sheet feed cassette 6F, a fixing unit 7, an ejection section 8 and an automatic duplex unit (ADU) 8B.
The automatic document feeder DF is provided on the top of the image forming apparatus A. The sheet processing apparatus B is connected to a sheet ejection section 8 provided on the left side surface of the image forming apparatus A illustrated in FIG. 1.
One surface or both surfaces of the document placed on the document table of the automatic document feeder DF is conveyed to be read by the optical system of the image reading section 1 and read into an image sensor 1A.
An image processing section 2 applies an analog process, an A/D conversion, a shading correction and an image compression process to an analog signal, to which photo-electric conversion has been applied by the image sensor 1A. Then the signal is transmitted to an image writing section 3.
In the image writing section 3, emitted laser beam from a semiconductor laser is irradiated onto a photosensitive drum 4A of an image forming section 4 and a latent image is formed on the photosensitive drum 4A. In the image forming section 4, processes such as charging, exposure, development, transfer, separation and cleaning are conducted. A transfer unit 4B transfers an image onto a sheet S, which has been respectively supplied to the first sheet feed sections 6A-6E from sheet feed cassettes 5A-5C, a manual feed tray 5D or a large capacity tray LT. A fixing unit 7 fixes the image onto the sheet S, which carries the image. The sheet S is conveyed to the sheet processing apparatus B from a sheet ejection section 8. Or, the image forming section 4 again applies a dual surface image process to the sheet S, which has been conveyed to an automatic duplex unit 8B by a conveyance path switching plate 8A. Then the sheet S will be ejected from the ejection section 8.

[Sheet Processing Apparatus]

The sheet processing apparatus B is configured by a sheet entrance section 10, a sheet ejection section 20, a sheet adding section (a cover sheet feeding section) 30, a punch processing section (a punching section, a first processing section) 40, a conveyance section 50, a folding section (a second processing section) 60 and a sheet stacking apparatus 100.
FIG. 2 illustrates a total structure drawing of a sheet processing apparatus B of the present invention.

(Sheet Entrance Section)

A sheet S, to which an image forming process has been applied by the image forming apparatus A, is guided to the sheet entrance section 10.
The recording sheet entrance position of the sheet entrance section 10 opposes to a recording sheet ejection position of the ejection section 8 of the image forming apparatus A.
The recording sheet S guided to entrance rollers 11 is branched (a branching section) to either the sheet ejection section 20 or the punch processing section 40 by a conveyance path switching member G1.

(Sheet Ejection Section)

When a punch process and a fold processing are not set, the conveyance path switching member G1 shuts off the conveyance path to the punch processing section 40 and opens the conveyance path to the sheet ejection section 20.
The recording sheet S, which passes through the first conveyance path P1 heading to the sheet ejection section 20, moves straight while being nipped by the conveyance rollers 21 and 22. Then the recording sheet S is ejected from the ejection section 20 by sheet ejection rollers 23 and stacked on a stacking tray 102 in the sheet stacking apparatus 100.
The recording sheet S, which has been branched upward in FIG. 2 in the downstream side of the sheet conveyance direction of the conveyance rollers 22 by a conveyance path switching member G2, passes through the conveyance rollers 25 of the sixth conveyance path P6. The recording sheet S is ejected by the sheet ejection rollers 26 and stacked onto a sub-stacking tray (a top tray) 27 as a single sheet processing ejection section disposed upper section of the sheet processing apparatus B. The sheet S, to which the fold processing has not been applied, is ejected onto the sub-stacking tray 27.

(Punch Processing Section 40)

The sheet S, which has been branched by the conveyance path switching member G1 of the sheet entrance section 10, is nipped by the conveyance roller 41 disposed at the lower section of the conveyance path switching member G1, and conveyed to a punch processing section (the first processing section) 40 (second conveyance path p2).
An aligning section 42 disposed on the conveyance path of the downstream side of the punch processing section 40 aligns the sheet width direction of the sheet S, to which the punch processing has not been applied.
A puncher of the punch processing section 40 is configured by a puncher, which is driven by a drive section (not shown), and a dice, which fits the blade section of the puncher. The sheet S, to which a punch processing has been applied, is conveyed to the downstream of a conveyance section 50 (a punching function).

(Conveyance Section 50)

The sheet S, which has been conveyed to a conveyance section 50, is nipped by the conveyance rollers 51, 52, 53 and 54 and conveyed to the fold processing section 60. The conveyance rollers 51, 52, 53 and 54 are configured by a drive roller, which is connected to a drive source and a driven roller, which is pressed and contacted by the drive roller. Each driven roller is connected with a solenoid SOL and arranged to contact to and separate from the drive roller.
The sheet S, to which no fold processing has been applied, among the small size sheets, to which the punch processing has been applied, passes through a third-A conveyance path 3A branched by a conveyance path switching member G3 and conveyed while being nipped by conveyance rollers 600. The large size sheet S, to which the punch processing has been applied, is conveyed to a third-B conveyance path 3B positioned under the branch position of the conveyance path switching member G3 irrespective to whether the fold processing has been applied or not. Then the large size sheet S is conveyed and guided into the fold processing section 60 by the conveyance rollers 53 and 54. Here, the third-A conveyance path 3A and the third-B conveyance path 3B configure the third conveyance path.
A conveyance path switching member 55 is provided in the conveyance section 50. The fold processing can be conducted on two sheets at the same time by storing and conveying two small size sheets. Further, it is apparent that it becomes possible to configure the apparatus so as to conduct the fold processing on each and every one of the sheet S without providing the conveyance path switching member 55.

(Fold Processing Section 60)

The sheet S, which has been conveyed to the fold processing section (the second processing section) 60 from the conveyance section 50, is nipped by registration rollers 601. Then the sheet S is conveyed to a first fold section 61, a second fold section 62 and a third fold section 63, where fold processing (folding functions) such as center-folding, Z-folding, outer-three-folding, inner-three-folding and inner-four-folding (also named gate-folding) will be conducted. Then the sheet S will be returned to the first conveyance path P1 through the fourth conveyance path P4.
FIGS. 3( a)-3(f) illustrate fold-processed sheets S, to which various fold processes such as the center-folding, the Z-folding, the outer-three-folding, the inner-three-folding and the inner-four-folding, have been applied. FIG. 3( a) illustrates the center-folding; FIG. 3( b) illustrates the Z-folding; FIG. 3( c) illustrates the outer-three-folding; FIG. 3( d) illustrates the inner-three-folding; FIG. 3( e) illustrates the double-parallel-folding; and FIG. 3( f) illustrates gate-folding. Unexamined Japanese Patent Application Publication No. 2005-15225 discloses detailed folding mechanisms.
FIG. 4 illustrates a cross sectional view of a sheet stacking apparatus 100 related to an embodiment of the present invention. FIG. 4 illustrates a situation where the sheet S is not on the stacking tray 102. FIG. 5 illustrates a cross sectional view of the stacking apparatus 100 and a situation where the sheet S is on the stacking tray 102. FIG. 6 illustrates a perspective view of a sheet stacking apparatus 100. FIG. 7 illustrates a relationship between sheet ejection rollers 23 and a rotary member 103 of the sheet processing apparatus B.
The sheet stacking apparatus 100 is attached to the sheet ejection section 20 of the sheet processing apparatus B.
The sheet stacking apparatus 100 includes a frame 101, to which various functional parts are attached, which will be described hereinafter.
The stacking tray 102 is supported by a frame 101 centering on a shaft 102 a in the downstream side of the conveyance direction of the sheet S in the left edge section of FIGS. 4 and 5, namely on the stacking tray 102, so as to be capable of rotating.
In FIGS. 4 and 5, the right edge section of the stacking tray 102, namely, in the upstream side of the conveyance direction of the sheet S on the stacking tray 102, is hung down by a wire 105. The other edge of the wire 105 is connected to a pull type spring 104. The stacking tray 102 is hung down at the both ends in the conveyance width direction by the wire 105.
One end of the spring 104 is attached to the frame 101 and the wire 105 is stretched around a pulley 106.
As described above, the upstream side in the sheet conveyance direction of the stacking tray 102 is held by the wire 105 so as to be capable of moving up and down. As described later, when the sheet S is stacked on the stacking tray 102 and as the mass of the stacked sheets S increases, the effect of the downward force against the stacking tray 102 descends the stacking tray 102.
Numeral 103 is a rotary member as a first sheet pressing member, which is attached to a shaft fixed onto a predetermined position of a frame 101, which is a stationary section, so as to freely rotate. The rotary member 103 guides the sheet S, which is ejected from the sheet ejection section 20 of the sheet processing apparatus B, to beneath the rotary member 103. At the same time, the rotary member 103 is a sheet pressing member for pressing the sheet S. The rotary member 103 touches the sheet S to be ejected and conveyed, and rotates according to the movement of the sheet S.
As illustrated in FIG. 7, the center of the rotation shaft 103 a of the rotary member 103 is positioned in the upper side of the extended line L from the nip NP formed by a pair of rollers forming the sheet ejection rollers 23. The lower edge 103 b of the rotary member 103, which forms a sheet pressing member for pressing the sheet S, is positioned in the lower side of the extended line L.
Based on the disposition and the configuration of the rotary member 103, the leading edge of the sheet S, which is ejected and conveyed from the sheet ejection section 20, hits the rotary member 103. However, since the center of the rotation shaft 103 a of the rotary member 103 is located in the upper side of the extended line L and the surface of the rotary member 103, which the leading edge of the sheet S hits, declines downward, the sheet S is securely guided under the lower side of the rotary member 103.
When the sheet S has left from the sheet ejection section 20, the rotary member 103 presses the sheet S at a constant height. Based on the pressing action of the rotary member 103, the trailing edge Sa of the sheet S is pressed down below the sheet ejection mouth of the sheet ejection section 20.
As described above, the sheet S, which has been folded and ejected, is securely stacked in a well aligned state onto the stacking tray 102 in an ejected order from the sheet ejection rollers 23 and stacked.
In order to set apart the trailing edge Sa, in the ejection direction of the sheet S, from the sheet ejection roller 23, it is preferable that the rotary member 103 be placed close to the sheet ejection rollers 23 as close as possible.
When the rotary member 103 is away from the sheet ejection rollers 23, the sheet S is bent between the sheet ejection rollers 23 and the rotary member 103 and even when the sheet S is pressed downward by the rotary member 103, there is a case that the trailing edge Sa of the sheet will not come apart from the sheet ejection rollers 23 and this may cause a sheet ejection jam.
The distance between the sheet ejection rollers 23 and the rotary member 103 is to be “D”, which is the distance between the center point “P” of the nip of a pair of rollers structuring sheet ejection rollers 23 (the center point in the sheet conveyance direction) and the shaft 103 a of the rotary member 103, the distance “D” is determined based on the relationship with the radius of the rotary member 103. When the radius of the rotary member is to be “R”, according to an example, distance “D” is set about three times of radius “R”. The relationship between “R” and “D” is as is illustrated in FIG. 7.
The sheet S is continuously ejected and conveyed from the sheet ejection section 20.
The rotary member 103 guides the ejected sheet S downward. Then the ejected sheet S runs on the stacking tray 102 in the left direction.
When the trailing edge Sa of the sheet S has left the sheet ejection rollers 23, the trailing edge Sa of the sheet S descends due to the effect of the rotary member 103. Then the sheet S immediately stops due to the pressing action of the rotary member 103.
Succeeding sheet S is stacked onto the preceded sheet S, which the rotary member 103 has held and pressed to move downward.
When the sheet S has been stacked on the stacking tray 102, the mass of the sheets S increases. Since the thickness of the stacked sheets increases, the sprig 104 extends corresponding to the increase of the mass of the sheets S. As a result, the right edge section of the stacking tray 102 descends.
Even when the folding condition of the sheet S is irregular, the right edge section of the stacking tray 102 descends corresponding to the mass of the sheets S. Thus, the stacking tray securely descends in response to the stacked amount of the sheets S.
Since the uppermost surface of the stacked sheets S is pressed by the pressing surface of the rotary member 103 at a constant height, the phenomenon that the stacked sheets largely bulge can be prevented.
When the right edge section of the stacking tray 102 has reached to the lowest limit position, an actuator 108 rotates and a sensor SE provided in the sheet processing apparatus B detects the rotation. Then, the full filling of the sheets is notified.
Based on the full filling detection signal, the display section of the image forming system (not shown) displays an instruction for taking out sheets from the stacking tray and the operation stops at the same time.
FIG. 8 illustrates a cross sectional view of the sheet stacking apparatus 100 of an embodiment of the present invention, where the sheet S is not on the stacking tray 102. FIG. 9 illustrates a cross sectional view of the sheet stacking apparatus 100 of an embodiment of the present invention, where the sheet S is on the stacking tray 102.
FIG. 10 illustrates a perspective view of the sheet stacking apparatus 100. FIG. 11 illustrates a relationship between sheet ejection rollers 23 and a rotary member 103 of the sheet processing apparatus B.
The sheet stacking apparatus 100 is attached onto the sheet ejection section 20 of the sheet processing apparatus B.
The sheet stacking apparatus 100 includes a frame 101, onto which various kinds of functional parts have been attached, which will be described below.
The frame 101 supports the stacking tray 102 at the shaft 102 a of the left edge section in FIGS. 8 and 9 so as to be capable of rotating centering on the shaft 102 a.
One end of the wire 105 is attached onto the right edge section of the stacking tray 102 and the other edge of the wire 105 is connected to the pull type spring 104 as shown in FIG. 8.
One end of the spring 104 is attached to the frame 101 and the wire 105 is stretched around a pulley 106.
As described above, the right edge section of the stacking tray 102 is held by the wire 105 so as to be capable of moving up and down. As described later, by the sheet S stacked onto the stacking tray 102, the effect of the downward force against the stacking tray 102 descends the stacking tray 102.
Numeral 103 is a rotary member as a sheet pressing member, which is attached to a shaft fixed on a predetermined position of a frame 101, which is a stationary section, so as to freely rotate. The rotary member 103 structures the first sheet pressing member for pressing the sheet S ejected from the sheet ejection section 20 of the sheet processing apparatus B. The rotary member 103 touches the sheet S to be ejected and conveyed, and rotates according to movement of the sheet S.
As illustrated in FIG. 11, the center of the rotation shaft 103 a of the rotary member 103 is positioned in the upper side of the tangential line L drawn at the nip NP between a pair of rollers forming the sheet ejection rollers 23. The lower edge 103 b of circumference of the rotary member 103, which presses and guides the sheet S, is positioned in the lower side of the tangential line L.
Based on the disposition and the configuration of the rotary member 103, the leading edge of the sheet S, which is ejected from the sheet ejection section 20, hits the rotary member 103. The sheet S is securely guided beneath the rotary member 103 after the leading edge of the sheet S hits the rotary member 103.
As described above, the rotary member 103 presses and holds the sheet S by the pressing surface including the lower edge 103 b having a constant height.
Numeral 107 denotes a pressing sheet as a second sheet pressing member.
The pressing sheet 107 includes a layered structure formed by polyethylene sheet whose lower surface, which contacts the sheet S, has been roughed and a PET (polyethylene terephthalate) sheet as a lining layer. The pressing sheet 107 is a sheet shaped member having an elastic characteristic. The right edge section of the pressing sheet 107, which is in the upstream side of the ejection direction of the sheet S, is fixed onto the frame 101. On the other hand, the left edge of Figure, which is positioned downstream side of the ejection direction of the pressing sheet 107, is movable. The surface, which contacts the sheet S of polyethylene, is formed into a rough surface having a friction resistor so as to prevent the sheet S to protrude from the stacking tray 101. The PET sheet enhances the rigidity of the pressing sheet 107 and strengthens the pressing action against the sheet S.
A rigid body sheet, which is supported so as to be capable of freely rotating as a pressing sheet 107 and biased by a spring, may also be used.
The left edge of the pressing sheet 107 is a free edge and the center portion of the stacking tray 102 is cut out as illustrated in FIG. 10. Therefore, when there is no sheet S on the stacking tray 102, the left edge of the pressing sheet 107 crosses the stacking tray 102 and extends downward beyond the stacking tray 102 (referring to FIG. 8).
When the sheet S has set apart from the sheet ejection section 20, the trailing edge Sa of the sheet S is pressed down below the ejection sheet mouth by the pressing action of the rotary member 103.
The conveyance of the sheet S is regulated to the left direction by the pressing 107. At the same time, the floating of the leading edge Sb of the sheet S is also regulated by the pressing sheet 107.
According to a kind of fold processing, there is a case that the sheet S, on which a multiple layered section is formed at the leading edge of the sheet in the conveyance direction by the fold processing, or there is a case that the sheet S, on which a multiple layered section is formed at the trailing edge of the sheet in the conveyance direction by the fold processing, is stacked. However, the floating of the multiply piled section in the leading edge section can be regulated by the pressing sheet 107, and the floating of the multiply piled section in the trailing edge can be regulated by the rotary member 103.
As described above, the folded sheet S is piled on the stacking tray 102 in the ejected order from the stacking tray sheet ejection section 20 and stacked in an aligned state.
The pressing sheet 107 as illustrated in FIG. 8, when no pressing sheet S is on the stacking tray 102, the pressing sheet 107 is arranged to cross the stacking tray 102 and extends to lower side of the stacking tray 102. Thus, the sheet S can be securely stacked on the stacking tray 102 in an aligned state from the level where the number of sheets S is small.
In order to set apart the trailing edge in the ejection direction of the sheet S from the sheet ejection rollers 23, it is preferred to place the rotary member 103 and the sheet ejection rollers 23 close by as much as possible.
The sheet S is continuously ejected and conveyed from the sheet ejection section 20.
The ejected sheet S is guided by the rotary member 103 in the downward direction and runs on the stacking tray 102 in the left direction along the lower surface of the pressing sheet 107.
When the trailing edge Sa in the ejection direction of the sheet S has left the sheet ejection rollers 23, the trailing edge Sa of the sheet S descends due to the effect of the rotary member 103. Then the sheet S immediately stops due to the pressing action of the pressing sheet 107.
Succeeding sheet S is stacked on the preceded sheet S, which the rotary member 103 has held and pressed to move downward.
As described above, since the sheet S securely leaves the sheet ejection rollers 23 just after the sheet S has been ejected, in the case of continuous ejection, a succeeding sheet is ejected and surely placed on the preceding sheet. The sheet is securely piled in ejected order on the stacking tray 102. Thus, sheets S are securely stacked in the ejection order from the sheet ejection section 20 and a page order will not be out of order when being stacked.
When the sheets S have been stacked on the stacking tray 102, the mass of the sheets S increases and the thickness of the stacked sheets also increase. Thus, the right edge section of the stacking tray 102 descends.
When the right edge section of the stacking tray 102 has reached to the lowest limit position, an actuator 108 rotates and a sensor SE provided in the sheet processing apparatus B rotates and detects the rotation. Then, the full fill of the sheets is notified.
Based on the full filling detection signal, the display section of the image forming system (not shown) displays an instruction for taking out sheets from the stacking tray and the operation stops at the same time.
FIG. 12 illustrates a cross sectional view of the sheet stacking apparatus 100 of an embodiment of the present invention, in which there is no sheet S on the stacking tray 102. FIG. 13 illustrates a cross sectional view of the sheet stacking apparatus 100, in which there is the sheet S on the stacking tray 102. FIG. 14 illustrates a perspective view of the sheet stacking apparatus. FIG. 15 illustrates a relationship between sheet ejection rollers 23 and a rotary member 103 of the sheet processing apparatus B.
The sheet stacking apparatus 100 is attached to the sheet ejection section 20 having a pair of sheet ejection rollers 23 of the sheet processing apparatus B.
The sheet stacking apparatus 100 includes a frame 101, to which various functional parts are attached, which will be described hereinafter.
The stacking tray 102 is supported by the frame 101 on a shaft 102 a, at the left edge portion of FIGS. 12 and 13 so as to be capable of rotating.
One end of the wire 105 is attached to the right edge portion of the stacking tray 102 in FIGS. 12 and 13, and the other edge of the wire 105 is connected to the pull type spring 104.
One edge of the spring 104 is attached to the frame 101 and at the same time the wire 105 is stretched around a pulley 106.
As described above, the right edge section of the stacking tray 102 is held by the wire 105 so as to be capable of moving up and down. As described later, since the sheet S is stacked onto the stacking tray 102, the effect of the downward force against the stacking tray 102 descends the stacking tray 102.
Numeral 103 denotes a rotary member attached to the shaft fixed on the frame 101 so as to be capable of freely rotating. The rotary member 103 guides the sheet S, which has been ejected from the sheet ejection section 20 of the sheet processing apparatus B, and structures a first sheet pressing member for pressing the sheet S. The rotary member 103 contacts the sheet S and rotates according to the movement of the sheet S.
As illustrated in FIG. 15, the center of the rotation shaft 103 a of the rotary member 103 is positioned in the upper direction of the tangential line L drawn at the nip NP in between a pair of rollers forming the sheet ejection rollers 23. The lower edge 103 b of the circumference of the rotary member 103, which presses and guides sheet S, is positioned in the lower direction of the tangential line L.
Based on the disposition and the configuration of the rotary member 103, the leading edge of the sheet S, which is ejected and conveyed from the sheet ejection section 20, hits the circumference of the rotary member 103. After the sheet S hits the circumference surface of the rotary member 103, the sheet S is securely guided beneath the rotary member 103.
Numeral 207 is a third sheet pressing member for pressing the sheet S. The third sheet pressing member 207 is structured by a leading edge stopper 207 a, which regulates the protuberance of the leading edge of the sheet S, and a sheet pressing section 207 b for pressing sheet S from the above of the sheet S.
The leading edge stopper 207 a is parallel with a trailing edge support wall 101 a for supporting the trailing edge in the conveyance direction of the sheet S on the stacking tray 102 formed on the frame 101.
As described above, due to the structure that the leading edge stopper 207 a is parallel with the trailing edge support wall 101 a, the sheet S is stacked on the stacking tray 102 in perfect order without bending.
Here, “parallel” does not mean that the angle formed by two lines is precisely 180° but also includes a case where the angle formed by two lines is slightly off from 180°.
The third sheet pressing member 207 is capable of moving to a retreated position, which is illustrated in a dotted line, and a pressing position, which is illustrated in a solid line.
The leading edge of the sheet S, which is ejected from the sheet ejection rollers 23, contacts the rotary member 103. Then the leading edge of the sheet S is guided beneath the rotary member 103. As the leading edge of the sheet S comes in contact with the third pressing member 207, the sheet S is stopped.
The rise of the leading edge in the conveyance ejection direction of the sheet S is regulated by the sheet pressing member 207 b and, at the same time, extend to the downstream in the conveyance ejection direction will be prevented by the leading edge stopper 207 a.
The trailing edge of the sheet S is pressed downward by the rotary member 103 just after the sheet has left the sheet ejection rollers 23.
As described above, the sheet S is stacked on the stacking tray 102 in aligned state as illustrated in FIG. 13.
When executing a continuous ejection operation, as the successive sheet S is guided by the rotary member against the preceded sheet S stacked on the sheet stacking tray 102, the leading edge stops at the step where the leading edge contacts the third sheet pressing member 207 and piled on the preceded sheet S.
As described above, the sheets S are stacked in the ejected order from the sheet ejection rollers 23 and a page order will not be out of order when stacked.
In response to the increase of stacking amount, the right edge section of the stacking tray 102 descends. However, when the stacking amount has reached the maximum stacking amount, the stacking tray 102 presses and rotates the actuator 109. Then, the sensor SE detects the rotation and outputs the full fill signal.
FIGS. 16 and 17 illustrate the other embodiments of the present invention. FIG. 16 illustrates a front cross sectional view and FIG. 17 illustrates a plan view of the sheet stacking tray 102.
In the embodiments, a leading edge sheet pressing member for pressing the leading edge in the conveyance direction of the sheet is provided. The members other than the leading edge sheet pressing member are the same as the embodiments illustrated in FIGS. 12-15.
As illustrated in FIG. 16, the pressing sheet 107 as a leading edge sheet pressing member presses the leading edge of the sheet S ejected from the sheet ejection rollers 23 and regulates the bulge of the stacked sheets S.
There are various kinds of forms of the fold-processed sheet S. For example, in the case of the Z-folding as illustrated in FIG. 3( b), the sheet S is ejected with the top edge portion, which has an overlapped portion formed by the folding of the sheets, the front section of the sheet S tends to bulge.
In the case of this kind of sheet, the pressing sheet 107 regulates the rise of the leading edge of the sheet S. At the same time, the sheet pressing member 207 also regulates the leading edge. Thus, the sheets S are stacked on the sheet ejection tray 102 in an aligned state.
The pressing sheet 107 includes a layered structure formed by polyethylene sheet whose lower surface contacts with the sheet S and has been roughed, and a PET (polyethylene terephthalate) sheet as a lining member. The right edge section of the FIG. 16 in the upstream side of the ejection direction of the sheet S, is fixed onto the frame 101. The left edge of pressing sheet 107, which is positioned downstream side of the ejection direction of the sheet, is movable. The surface, which contacts the sheet S of polyethylene, is formed into a rough surface having a friction resistor so as to prevent the sheet S to protrude from the stacking tray 101. The PET sheet enhances the rigidity of the pressing sheet 107 and strengthens the pressing action against the sheet S.
A rigid body sheet, which is supported so as to be capable of freely rotating and biased by a spring, may also be used as a pressing sheet 107.
FIG. 18 illustrates a block diagram of a control system of an image forming system and FIG. 19 illustrates a flowchart of a control for a sheet processing apparatus.
The sheet pressing member 207 positions at the retreated position as shown by a dotted line in FIG. 12 before starting the operation of the sheet processing apparatus B.
Based on an operation command transmitted from the image forming apparatus A (STEP 1), determination of whether it corresponds to M or N is conducted in STEP 2.

	TABLE 1

		Other than
	Multiple	multiple
	folding	folding

Thin sheet of	small size	M	N
paper
	other than	N	N
	small size
Other than thin	small size	N	N
sheet of paper
	other than	N	N
	small size

In Table 1, the thin sheet of paper denotes a sheet of paper having not more than comparative weight of 71 g/mm², the small size denotes a sheet having a length of not more than 297 mm in a conveyance direction of a sheet, to which the fold processing has not been applied yet, such as A4 size, and a multiple fold denotes a folding method having not less than triple fold, such as gate-folding and double parallel folding.
Examples in Table 1, in the case of a thin sheet of paper of not more than A4 size, the sheet S has been stacked in perfect order by positioning the third sheet pressing member 207 at the pressing position.
In the case of the sheets other than the thin sheet of paper of not more than A4 size, based on the aligning effect of the rotary member 103, even though the sheet pressing member has been retreated, sheets have been stacked in perfect order.
The determination illustrated in Table 1 is an example. The determination illustrated in Table 1 will be modified into various ways. The third sheet pressing member 207 can be selectively positioned at the pressing position or the retreated position corresponding to at least one of the modifications in the sheet size, a sheet kind and a fold kind.
Further, the examples illustrated in Table 1, an image forming apparatus controller 200 controls the sheet pressing member 107 in response to the comparative weight of the sheet according to the kinds of sheets S. However, it is also possible to be sorted out by the rank based on the kinds of sheets S, such as a normal sheet of paper and a coated sheet of paper, which includes quality of a sheet of paper.
A sheet processing apparatus controller 110 communicates with the image forming apparatus controller 200 to conducts the determination illustrated in Table 1 in STEP 2 according to the setting in the sheet type setting section 210 a and a setting section of fold processing 210 b of an operation section 210 in the image forming apparatus A.
When conducting a print operation and a fold processing based on the command from the external apparatus (not shown), the information pertaining to the sheet size, the sheet kinds and kinds of fold processing will be given by receiving the information at a communication section 211 for communicating with external apparatuses.
When the sheet corresponds to M (M in STEP 2), motor 111 will be activated (started) to set the sheet pressing member 207 at a solid line position as illustrated in FIG. 12 (STEP 3). When the sheet corresponds to N, the process is finished without conducting work.
When having set the third sheet pressing member 207, having conducted sheet stacking and having completed the jobs (STEP 4: YES), the motor 111 is activated to return the third sheet pressing member 207 to the retreated position illustrated by a dotted line (STEP 5).

Claims

1. A sheet stacking apparatus comprising:

(a) a stacking tray which stacks a fold-processed and ejected sheet, and descends in response to a mass of stacked sheets; and

(b) a first sheet pressing member which holds the stacked sheets downward from an upper side of the stacked sheets at a constant height.

2. The sheet stacking apparatus of claim 1, further comprising a spring which urges upward and holds the stacking tray.

3. The sheet stacking apparatus of claim 1, wherein the first sheet pressing member guides downward the sheet being conveyed to the stacking tray.

4. The sheet stacking apparatus of claim 2, wherein the stacking tray is pivotally supported at an edge portion of a downstream side in an ejection direction of the sheet, and is held and urged upward by the spring so as to be capable of moving up and down at an edge portion of an upstream side in the ejection direction.

5. The sheet stacking apparatus of claim 1, wherein the first sheet pressing member comprises a rotary member which comes in contact with the sheet being conveyed and rotates according to movement of the sheet, and presses downward a trailing edge of the sheets in the ejection direction, which have been stacked on the stacking tray.

6. A sheet stacking apparatus comprising:

(a) a stacking tray which stacks a fold-processed and ejected sheet;

(b) a first sheet pressing member which presses a trailing edge of a sheet in an ejection direction of the sheet at a constant height; and

(c) a second sheet pressing member which presses a leading edge of the sheet on the stacking tray in the ejection direction of the sheet,

wherein the second sheet pressing member is supported by a stationary section at an edge on upstream side in the ejection direction of the sheet and an edge on downstream side of the second sheet pressing member in the ejection direction of the sheet is a free edge.

7. The sheet stacking apparatus of claim 6, wherein the first sheet pressing member comprises a rotary member which comes in contact with the sheet being conveyed and rotates according to movement of the sheet.

8. The sheet stacking apparatus of claim 6, wherein the first sheet pressing member guides downward the sheet being conveyed.

9. The sheet stacking apparatus of claim 6, wherein the second pressing member is a sheet shaped member having an elastic characteristic.

10. The sheet stacking apparatus of claim 6, wherein the stacking tray is pivotally supported at an edge portion of a downstream side in a conveyance direction of the sheet, and is urged upward by a spring at an edge portion of an upstream side in the conveyance direction.

11. The sheet stacking apparatus of claim 6, wherein when the sheet is not stacked on the sheet stacking tray, the free edge of the second pressing member protrudes downward from the stacking tray.

12. The sheet stacking apparatus of claim 6, wherein the second pressing member comprises a layer having a surface in contact with the sheet in which friction of the surface is adjusted, and a lining layer which enhances rigidity of the second pressing member.

13. A sheet stacking apparatus for stacking a fold-processed and ejected sheet comprising:

(a) a stacking tray which stacks a sheet;

(b) a third sheet pressing member which holds a sheet, which has been stacked on the stacking tray; and

(c) a control member which controls the third sheet pressing member,

wherein the control member selectively places the third sheet pressing member at either a pressing position where the third sheet pressing member presses the sheet or an retreated position where the third sheet pressing member has retreated from the sheet in response to at least one of a sheet size, a sheet type, and a type of fold processing.

14. The sheet stacking apparatus of claim 13, wherein the third sheet pressing member comprises a leading edge stopper at which a leading edge of the sheet in an ejection direction hits.

15. The sheet stacking apparatus of claim 13, wherein the third sheet pressing member comprises a sheet pressing section which presses downward the sheet stacked on the sheet stacking tray.

16. The sheet stacking apparatus of claim 14, further comprising a trailing edge support wall which receives a trailing edge of the sheet stacked on the sheet stacking tray in the ejection direction, and the leading edge stopper is parallel with the trailing edge support wall.

17. The sheet stacking apparatus of claim 13, wherein the control member places the third sheet pressing member at the pressing position when the sheet is ejected, and at the retreated position when the sheet is not ejected.

18. The sheet stacking apparatus of claim 13, further comprising a first sheet pressing member which guides the sheet when ejecting the sheet to the sheet stacking tray, and presses downward a trailing edge of the sheets in the ejection direction, which have been stacked on the stacking tray.

19. A sheet processing apparatus including a fold processing section which conducts a fold processing of a sheet, an ejection section which ejects a fold-processed sheet and a sheet stacking apparatus which stacks the sheet, which has been ejected from the ejection section, the sheet stacking apparatus comprising:

(a) a stacking tray, which is capable of descending in response to a mass of stacked sheets, to which the fold process has been applied and ejected from the ejection section; and

(b) a sheet pressing member which presses the stacked sheets downward from an upper side of the stacked sheet at a constant height.

20. The sheet processing apparatus of claim 19, wherein the ejection section comprises sheet ejection rollers formed by a pair of rollers, the first sheet pressing member comprises a rotary member which comes in contact with the sheet being conveyed and rotates according to movement of the sheet, and the rotary member is arranged so that a center of a rotation shaft of the rotary member is positioned in an upper side of an extended line from a nip formed by the sheet ejection rollers and a sheet pressing surface of the rotary member is positioned in a lower side of the extended line.

21. A sheet processing apparatus including a fold processing section for conducting a fold processing of a sheet, ejection rollers constituted of a pair of rollers, an ejection section for ejecting a sheet processed by the fold processing section, and a sheet stacking apparatus for stacking a sheet ejected from the ejection section, the sheet finisher comprising:

(a) a stacking tray which stacks a sheet, to which the fold process has been applied by the fold processing section and ejected from the ejection section;

(b) a first sheet pressing member which presses a trailing edge of the sheet in an ejection direction of the sheet at a constant height; and

wherein the second sheet pressing member is supported by a stationary section in an edge on upstream side in the ejection direction of the sheet and an edge on downstream side of the second sheet pressing member in the ejection direction of the sheet is a free edge.

22. The sheet processing apparatus of claim 21, wherein the first sheet pressing member comprises a rotary member which comes in contact with the sheet being conveyed and rotates according to movement of the sheet, and the rotary member is arranged so that a center of a rotation shaft of the rotary member is positioned in an upper side of an extended line from a nip formed by the sheet ejection rollers and a sheet pressing surface of the rotary member is positioned in a lower side of the extended line.