JP2023121495A - Sheet loading device and image formation system provided with sheet loading device - Google Patents

Abstract

To provide a sheet loading device which surely prevents curling that can be generated in Z-folded sheets and the tip of a sheet bundle discharged to a loading tray, and can obtain good sheet alignment property and loading property.SOLUTION: A sheet loading device C lifts a first loading tray 24 to a second or third height position higher than a first height position when a non-Z-folded sheet is discharged before discharge by a discharge roller 48 pair, in the case where the sheet discharged to the first loading tray 24 is a Z-folded sheet or a Z-folded sheet bundle, and lowers the first loading tray 24 from the second or third height position corresponding to the discharge operation by the discharge roller 48 pair.SELECTED DRAWING: Figure 12

Description

The present invention relates to a sheet stacking device for stacking folded sheets on stacking means, and an image forming apparatus including the same, such as a copying machine, a printer, a facsimile machine, and a multi-functional machine.

2. Description of the Related Art Conventionally, a sheet stacking device has been used for stacking sheets on which images have been formed by an image forming apparatus on stacking means such as a stacking tray. When the sheets from the image forming apparatus are directly stacked on the stacking means, the sheet stacking apparatus is configured as a separate apparatus integrated with or externally attached to the image forming apparatus, or a post-processing apparatus is externally attached to the image forming apparatus. When the sheets from the image forming apparatus are subjected to post-processing such as binding processing, shift processing, folding processing, etc., the post-processing device is integrated with the post-processing device or configured as a separate device attached externally.

In many sheet stacking devices, a sheet conveyed from an image forming apparatus is discharged from a discharge opening onto a stacking tray by a pair of discharge rollers rotating at a predetermined speed. At this time, if the discharged sheet is thin paper with low stiffness or a bundle of a plurality of sheets, the leading edge of the sheet may be curled on the stacking tray, causing a stacking failure. Therefore, there is known a stacking device in which the operation mode can be switched between a first mode in which sheets are discharged one by one from a pair of discharge rollers and a second mode in which a bundle of sheets is discharged (see, for example, Japanese Unexamined Patent Application Publication No. 2002-100002). ). In this device, the sheet discharge tray is arranged at the bottom in the first mode, and is kept at the top in the second mode to prevent the sheet from curling during discharge.

Similarly, to prevent paper from being stacked in a curled state on the output tray, move the output tray to an upper position so that the leading edge of the stack of paper ejected by the output roller does not hang down. A sheet stacking device is known (see, for example, Japanese Unexamined Patent Application Publication No. 2002-200023). Further, when the trailing edge of the paper is discharged, the paper discharge tray is moved downward by a predetermined distance, and when a predetermined time elapses after the movement, it is moved to an upper position. up to the end fence of

On the other hand, the folding process performed on the sheet on which the image is formed includes folding the sheet in two at the center position along the sheet conveying direction, folding in three by folding the sheet inward at two points, and folding inward and outward alternately. There is a so-called Z-fold that folds in three (see, for example, Patent Document 3). The sheet folding device disclosed in Japanese Patent Application Laid-Open No. 2002-200000 is arranged upstream in the sheet conveying direction as a device independent from the post-processing device.

JP 2013-245058 A JP-A-10-291723 JP 2020-93855 A

However, in the conventional devices described in Patent Documents 1 and 2, the discharged sheets are sheets or sheet bundles that are not folded and have a uniform shape along the sheet conveying direction. However, among the folded sheets, the Z-folded sheet in particular has a downstream portion that is Z-folded along the sheet conveying direction, as described in Patent Document 3, and has a thickness of three sheets. , and is heavier than the unfolded sheet.

Therefore, when the Z-folded sheet is ejected by the ejection rollers, the edge of the Z-folded sheet hangs down and comes into contact with the stacking surface of the stacking tray or the upper surface of the sheet previously stacked on the stacking tray, and is curled by the frictional resistance generated between them. will be discharged with the In addition, if a plurality of Z-folded sheets are held in a state of being nipped by the discharge roller near the center in the conveying direction in order to perform post-processing such as binding, the sheet is cantilevered by the discharge roller over time. On the other hand, the leading edge of the Z-folded sheet hangs down more, and the leading edge of the Z-folded sheet tends to curl when the sheet is discharged onto the stacking tray. As a result, there is a possibility that the stackability and alignment of the sheets on the stacking tray may be further deteriorated.

However, the conventional apparatuses described in Patent Documents 1 and 2 cannot reliably prevent the leading edge from curling, which tends to occur when the Z-folded sheet and the Z-folded sheet bundle are discharged onto the stacking tray. In particular, as described in Japanese Patent Application Laid-Open No. 2002-100002, if the stacking tray is kept waiting at the upper position when the sheet bundle is discharged, as the number of Z-folded sheets or Z-folded sheet bundles to be discharged increases, the leading end portion of the Z-folded sheet or the Z-folded sheet bundle is shifted backward. Since it is thicker and taller than the end side (upstream side) portion, the leading edge of the subsequent Z-folded sheet or the Z-folded sheet bundle is likely to get caught on the upper surface of the already-stacked sheets, which increases the possibility of curling up and loss of alignment. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described conventional problems. To provide a sheet stacking device capable of reliably preventing curling of the leading edge of a sheet and obtaining good alignability and stackability of sheets and sheet bundles.

In order to solve the above problems, the sheet stacking device of the present invention includes:
a loading means for loading sheets;
a discharging means for discharging the sheet conveyed in a predetermined conveying direction to the stacking means;
and a lifting means for lifting and lowering the loading means,
When the sheet to be discharged to the stacking means by the discharging means is a Z-folded sheet that has been Z-folded, the lifting means is configured to perform Z-folding before the Z-folded sheet is discharged to the stacking means by the discharging means. The stacking means is moved to a second height position higher than the first height position for discharging the unfolded non-Z-folded sheet, and the discharge means moves the Z-folded sheet to the stacking means. It is characterized in that the loading means is lowered from the second height position in correspondence with the operation of discharging.

The image forming system of the present invention is
the above-described sheet stacking device of the present invention;
an image forming apparatus that discharges a sheet on which an image has been formed;
and a folding device that Z-folds the sheet from the image forming apparatus and supplies the sheet to the sheet stacking device.

According to the present invention, before discharging the Z-folded sheet and the Z-folded sheet bundle, the stacking tray is lifted to a high position by the lifting means and then lowered in correspondence with the discharging operation, thereby preventing the leading edge from curling. Good sheet alignment and stackability can be obtained.

1 is an overall configuration diagram showing an embodiment of an image forming system according to the present invention; FIG. FIG. 2 is an overall configuration diagram of the sheet stacking device in FIG. 1; FIG. 3 is a partially enlarged view of FIG. 2 showing the periphery of the end surface binding portion of the sheet stacking device; FIG. 4 is an explanatory view showing driving of a conveying roller, an exit roller, and a branch roller in the sheet stacking device; FIG. 4 is an explanatory diagram of elevation positions of the first stacking tray in the sheet stacking device; FIG. 2 is a schematic configuration diagram showing the essential parts of the folding device; 4(a) to 4(d) are explanatory diagrams showing the Z-folding operation of a sheet by the folding device in the order of steps. 8(e) to 8(h) are explanatory diagrams showing the order of steps of the Z-folding operation following FIG. 7; FIG. 4A to 4C are explanatory diagrams showing a stacking operation for discharging a sheet bundle without Z-folding onto a first stacking tray in the order of steps; FIG. 10(d) and 10(e) are explanatory diagrams showing the stacking operation following FIG. 9 in the order of steps; FIG. 4(a) to 4(d) are explanatory diagrams showing a stacking operation for discharging a Z-folded sheet bundle onto a first stacking tray in order of steps. 12(e) to 12(g) are explanatory diagrams showing the stacking operation following FIG. 11 in order of steps; 4 is a flowchart of an operation for discharging a sheet bundle to the first stacking tray;

Preferred embodiments of a sheet stacking device and an image forming system according to the present invention will be described in detail below with reference to the accompanying drawings.

In the accompanying drawings, FIG. 1 is an overall configuration diagram showing an image forming system provided with an image forming apparatus A, a folding processing apparatus B, and a sheet stacking apparatus C according to the present invention. As will be described later, the folding device B Z-folds the sheet from the image forming device A. FIG. The sheet stacking device C subjects the sheets from the folding device B to staple processing, alignment processing, etc. as necessary, and then discharges and stacks them on the first stacking tray 24 on the downstream side. The image forming apparatus A includes, for example, copiers, printers, printers, and other apparatuses having various structures. The image forming apparatus A, the folding device B, and the sheet stacking device C will be described in detail below.

[Image forming apparatus]
The image forming apparatus A, as shown in FIG. 1, includes an image forming unit A1, an image reading unit A2, and a document feeding unit A3. The image forming unit A1 includes a paper feeding section 202, an image forming section 203, a paper discharging section 204, and a data processing section 205 in an apparatus housing 201. As shown in FIG.

The paper feeding unit 202 includes a plurality of cassettes 202a, 202b, 202c, and 202d, and each of the cassettes 202a, 202b, 202c, and 202d can store sheets S of different standard sizes that have been selected in advance. . Each of the cassettes 202a, 202b, 202c, and 202d incorporates a separating mechanism that separates the sheets S inside one by one and a sheet feeding mechanism that feeds out the sheets S. As shown in FIG. Sheets S stored in the sheet feeding unit 202 having such a configuration are fed to the sheet feeding path 206 in a size specified by a main body control unit (not shown). In the paper feeding path 206, there are conveying rollers 207 arranged in the middle and conveying the sheets S supplied from the plurality of cassettes 202a, 202b, 202c, and 202d to the downstream side, and conveying rollers 207 arranged at the end of the path for conveying the sheets S to the leading edge. A registration roller 208 for aligning is provided, and the sheet S whose leading edge is aligned by the registration roller 208 is fed to the image forming unit 203 on the downstream side at a predetermined timing.

The image forming unit 203 may be configured to form an image on the sheet S fed from the paper feeding unit 202, and various image forming mechanisms can be employed. In the illustrated embodiment, the imaging station 203 is shown as an electrostatic imaging mechanism. However, the image forming unit 203 is not limited to the illustrated electrostatic image forming mechanism, and may employ an ink jet image forming mechanism, an offset image forming mechanism, or the like.

The image forming unit 203 shown in FIG. 1 includes a photoreceptor 210 (drum, belt) and a light emitter 209 for emitting an optical beam to the photoreceptor 210. A developing device 211 (developer) and a cleaner are provided. (not shown) are arranged around the rotating photoreceptor 210 . The illustrated one is a monochrome printing mechanism, in which a light emitting device 209 optically forms a latent image on a photosensitive member 210, and a developing device 211 adheres toner ink to the latent image. The ink image (ink toner) adhered to the photosensitive member 210 is image-transferred by the transfer charger 212 onto the sheet S fed from the paper feeding unit 202. After the image-transferred sheet S is fixed by the fixing roller 13, It is sent to the discharge path 218 . Further, the image forming unit 203 is provided with a circulation path 216 , and after the sheet S from the discharge path 218 is turned upside down in a switchback path, it is sent to the registration rollers 208 again, and an image is formed on the back side of the sheet S. and sent to the discharge path 218 . A paper discharge roller 215 is arranged in the paper discharge path 218, and a paper discharge port 214 is formed at the end thereof. do.

Above the image forming unit A1 configured as described above, a document reading unit A2 for optically reading a document image formed by the image forming unit 203 is provided. A feeding unit A3 is mounted.

The image reading unit A2 includes a first platen 223 and a second platen 224 made of transparent glass, a reading carriage 221, a light source mounted on the reading carriage 221, a photoelectric conversion element 222, mirrors and lenses. and a reduction optical system 225 configured in combination, scanning the reading carriage 221 along the first platen 223 to apply light from the light source to the image of the document sheet S placed on the first platen 223 . The light reflected from the image on the document sheet S is guided to the photoelectric conversion element 222 by the reduction optical system 225, and the image is read. The photoelectric conversion element 222 converts the image data into an electric signal and transfers the electric signal to the image forming unit 203 .

The document feeding unit A3 includes a paper feeding tray 226, a paper feeding path 227, and a paper discharge tray 228, and conveys documents placed on the paper feeding tray 226 one by one along the feeding path 227. Then, it passes over the second platen 224 and is discharged to the discharge tray 228 . When reading a document fed from the document feeding unit A3 and passing over the second platen 224, the reading carriage 221 is previously stopped below the second platen 224, and the reading carriage 221 is stopped above the second platen 224. to generate image data from the image passing through the .

[Folding device]
The folding device B connected to the image forming apparatus A is a device that receives the image-formed sheet S ejected from the sheet ejection port 214 of the image forming apparatus A and performs Z-folding.

FIG. 6 shows the internal configuration of the folding device B. As shown in FIG. Inside the folding device B, a transport path 301 extending in a substantially horizontal direction is provided. On the conveying path 301, one or more conveying roller pairs 302 and a folding mechanism 303 disposed downstream of the conveying roller pairs 302 are provided. An additional folding unit 304 is provided at the end of the partial conveying path 318 . The folding processing apparatus B folds the sheet S conveyed along the conveying path 301 by the folding mechanism 303 , and then folds the sheet S conveyed along the folding portion conveying path 318 by the additional folding unit 304 . Further folding processing is performed, and the sheet S subjected to the folding processing and the additional folding processing can be handed over to the sheet stacking device C.

As shown in FIG. 1, the transport path 301 is arranged so as to be continuous with the sheet ejection port 214 of the image forming apparatus A, and the sheet S ejected from the sheet ejection port 214 is transported through the transport path 301. It can be carried into the side folding processing device B. As shown in FIG. Further, the discharge port of the additional folding unit 304 at the end of the folding portion conveying path 318 is also arranged so as to be continuous with the carry-in port 30 of the sheet stacking device C, and the sheet S discharged from the additional folding unit 304 passes through the carry-in port 30. can be carried into the sheet stacking device C by pressing.

The conveying roller pair 302 is formed of a rubber roller and a driven roller, and includes an upper conveying roller 302a arranged on the upper side and a lower conveying roller 302b arranged on the lower side facing the upper conveying roller 302a. there is In this embodiment, the upper conveying roller 302a is connected to a conveying roller drive motor (not shown) and rotates as the conveying roller drive motor rotates, while the lower conveying roller 302b It is pressed against the upper conveying roller 302a by the biasing force of a spring (not shown), and is driven to rotate. However, the conveying roller pair 302 is not limited to the above configuration as long as the sheet S can be conveyed, and an appropriate configuration can be adopted.

The folding mechanism 303 is composed of a pair of folding rollers 305 and a veneer 307 . The folding roller pair 305 is formed of rubber rollers, and includes an upper folding roller 305a arranged on the upper side and a lower folding roller 305b arranged on the lower side facing the upper folding roller 305a. The lower folding roller 305b is pressed against the upper folding roller 305a by the biasing force of a spring (not shown), and the upper folding roller 305a and the lower folding roller 305b are driven by a common folding roller drive motor (not shown). They are connected to each other and rotate in opposite directions as the folding roller drive motor rotates. The sliced plate 307 is arranged between the conveying roller pair 302 and the folding roller pair 305 and is connected to a sliced plate driving motor (not shown). It is designed to move parallel to the transport path on the side.

An upper transport guide 308 , a lower transport guide 309 , an upper folding guide 310 , and a lower folding guide 311 are provided in the transport path 301 and the folding portion transport path 318 between the transport roller pair 302 and the folding roller pair 305 . is provided.

The upper conveying guide 308 is formed from immediately behind the conveying roller pair 301 to above the thrust plate 307 so as to guide the leading edge of the sheet S from the conveying roller pair 310 to the thrust plate 307 . The upper conveying guide 308 is for regulating the flow of the sheet S conveyed along the conveying path 301, is arranged above the conveying path 301, and has a shape bent downward toward the downstream side. . Further, the upper folding guide 310 is arranged from between the upper conveying guide 308 and the folding roller pair 305 to the downstream side of the folding roller pair 305, and guides the folding roller pair 305 to the leading edge of the sheet S and a folded portion of the sheet S, which will be described later. It has a guide shape that guides. The upper folding guide 310 is for regulating the flow of the sheet S in the folding mechanism 303 , and is provided downstream of the upper transport guide 308 and above the folded portion transport path 318 .

The lower conveying guide 309 is for regulating the flow of the sheet S conveyed along the conveying path 301, and is arranged below the conveying path 301. Similar to the upper conveying guide 308, the lower conveying guide 309 is arranged downstream. It has a downward curved shape. The lower transport guide 309 is discontinued before the veneer 307 , and an open space is formed downstream of the lower transport guide 309 . The lower folding guide 311 is disposed on the downstream side of the veneer 307 and extends across the upstream and downstream sides of the folding roller pair 305 . The portion has a horizontal surface for guiding the leading edge of the conveyed sheet S and a folded portion of the sheet S, which will be described later, to the nip portion of the folding roller pair 305, and an inclined surface for facilitating the guiding to the horizontal surface.

The sliced plate 307 is horizontally moved by a sliced plate driving device and a control unit (not shown). The thrust plate 307 fills the space between the lower conveying guide 309 and the lower folding guide 311 when the conveying roller pair 302 conveys the sheet S along the conveying path 301 to the folding roller pair 305 . It is arranged so as to guide the leading edge of the conveyed sheet to the lower folding guide 311 . When the control unit recognizes that the leading edge of the sheet S has been nipped by the pair of folding rollers 305, the control unit horizontally moves the veneer 307 below the lower conveying guide 309 to form a folded portion. A space for forming a loop is formed between the side conveying guide 309 and the lower folding guide 311 . After the space for forming the loop is formed, when the sheet S is conveyed by a predetermined amount in a state where the leading edge of the sheet S is nipped by the pair of folding rollers 305, the intermediate portion of the sheet bends downward in the space for forming the loop, forming a loop. Create a section. In this state, the sliced plate 307 is moved horizontally toward the folding roller pair 305 to form a folded portion. By conveying the sheet S, a fold is formed.

A plurality of additional folding rollers 314 are arranged in a row in the direction of the fold of the sheet in the pressing member arrangement area and spaced apart from each other at regular intervals, and are supported by the additional folding guides 313 . Further, the plurality of additional folding rollers 314 are moved toward and away from the lower side folding guide 311 by the first moving mechanism that vertically moves the additional folding guide 313 that supports the plurality of additional folding rollers 314. A pressing position where the fold of the sheet S arranged between the additional folding rollers 314 and the lower folding guide 311 is pressed by the additional folding rollers 314 and the lower folding guide 311 . and a retracted position where the plurality of additional folding rollers 314 are moved in a direction away from the sheet S from the pressing position, and a second moving mechanism for moving the additional folding guide 313 back and forth. By moving the additional folding guide 313 in the horizontal direction, it can be moved along the fold of the sheet S. As shown in FIG.

The length of the pressing member arrangement area (that is, the distance between the additional folding rollers 314 arranged at the extreme positions of the pressing member arrangement area) is adjacent to one extreme position when moved from the retracted position to the pressing position. One end of the fold of the sheet (the end on the upstream side in the movement direction of the additional folding rollers 314) is arranged between the two additional folding rollers 314 arranged at the same position, and the additional folding is arranged at the other extreme position. A roller 314 is defined to be positioned on the crease. Preferably, the length of the pressing member arrangement area, that is, the length between the additional folding rollers 314 arranged at the extreme positions of the pressing member arrangement area is longer than the fold length of the sheet S carried into the additional folding unit 304. is shortened by one pitch of the arrangement of the additional folding rollers 314 (one interval between two adjacent additional folding rollers). In this case, the number of additional folding rollers 314 required can be reduced, and the cost of the additional folding rollers 314 can be reduced. In addition, since the number of additional folding rollers 314 supported by the support member 312 is reduced, when the same force is applied to the support member 312, the pressing force per additional folding roller 314 against the sheet S is increased. is enhanced, and efficient additional folding is possible with a smaller force.

In the additional folding unit 304 , a plurality of additional folding rollers 314 are arranged at a receiving position away from the lower folding guide 311 toward the retracted position or the pressing position, and the sheet is inserted into the additional folding unit 304 . After receiving the sheet S, the position of the sheet S is detected by sheet position detection means (not shown) provided upstream of the folding roller pair 305 , and the fold of the sheet S reaches below the additional folding roller 314 . When the sheet S is stopped, the first moving mechanism moves the plurality of additional folding rollers 314 to the pressing position with respect to the lower folding guide 311 . When the plurality of additional folding rollers 314 move to the pressing position, one end of the fold (the upstream end in the direction of movement along the fold) of the sheet S is positioned at one extreme position in the pressing member arrangement area. , while the other end of the fold (end on the downstream side in the direction of movement along the fold) is outside the pressing member arrangement area (i.e., the pressing member arrangement area outside of the additional folding roller 314 at the other extreme position in the direction) is carried into the additional folding unit 304 .

Further, by moving the plurality of additional folding rollers 314 along the folds of the sheet S with respect to the lower folding guide 311 at the pressing position by the second moving mechanism, the plurality of additional folding rollers 314 fold the sheets S. Further folding is performed by pressing over the entire crease to strengthen the crease. Thus, each additional folding roller 314 and the lower folding guide 311 function as pressing members.

Note that the gaps between the plurality of additional folding rollers 314 and the lower folding guide 310 and the gaps between the bottom surfaces of the additional folding guides 313 and the lower folding guide 110 extend over the entire area in the direction along the fold of the sheet S. kept constant.

The plurality of additional folding rollers 314 are rotatably attached to auxiliary members 313 that are movably supported, and are biased toward the lower folding guide 311 by springs (not shown). It is preferable that With this configuration, when the additional folding unit 304 moves downward toward the lower folding guide 311, the additional folding roller 314 stops moving downward when it contacts the lower folding guide 311. On the other hand, due to the contraction of a spring (not shown), the additional folding rollers 314 can apply a constant pressing force to the folds of the sheet S, and the pressing force varies depending on the folds to perform non-uniform additional folding. can be suppressed.

Next, a detailed configuration of the mechanism for Z-folding in the illustrated embodiment will be described.

As shown in FIG. 7A, a conveying path 301 formed by an upper conveying guide 308 and a lower conveying guide 309 is arranged so as to be continuous with the sheet discharge port 214 of the image forming apparatus A. The openings of the upper transport guide 308 and the lower transport guide 309 are widened. The sheet S ejected from the sheet ejection port 214 can be carried into the folding processing apparatus B via the transport path 301, and the sheet S is transported through a transport roller pair 302 formed of a rubber roller and a driven roller. .

In FIG. 7B, the sheet S received from the image forming apparatus A is conveyed by the conveying roller pair 302, and after the leading edge of the sheet S is nipped by the folding roller pair 305, the veneer 307 retreats to form a loop. It shows the starting state. In the conveying path on the downstream side of the conveying roller pair 302 , the upper conveying guide 308 and the upper folding guide guide the sheet S to the folding roller pair 305 . On the lower side, the sheet S is guided by a lower conveying guide 309 , a thrust plate 307 waiting below the lower conveying guide 309 on the downstream side, and a lower folding guide 311 . The leading edge of the sheet S is detected by a sheet leading edge position detection sensor (not shown), and at the timing when it is nipped by the folding roller pair 305, the folding roller pair stops conveying and the thrust plate 307 retreats in the upstream direction. to form a loop space. Further, the upper conveying guide 308 is inclined downward as it proceeds downstream, and has a shape that allows the sheet S to be formed in the loop space without load.

FIG. 7(c) shows a state in which the sliced plate 307 moves to the retracted position, and the conveying roller pair 302 continues conveying while the folding roller pair 305 stops conveying, thereby forming a loop in the loop space. showing.

FIG. 7D shows a state in which the veneer 307 moves to the retracted position, and the conveying roller pair 302 continues conveying while the folding roller pair 305 stops conveying, thereby forming a loop in the loop space. showing.

In FIG. 8E, the sliced plate 307 touches the loop of the sheet S, moves further downstream, stops just before the folding roller pair 305, and the portion where the sheet S is pushed into the folding roller pair 305 is The state of entering and forming the first fold is shown. At a predetermined timing when the thrust plate 307 moves to the thrust position, the stopped folding roller pair 305 starts to be driven to start conveying the sheet S to the downstream side.

In FIG. 8(f), the veneer 307 is retracted from the thrust position to the retracted position on the upstream side and stopped. The sheet S is conveyed by the pair of folding rollers 305 and the pair of conveying rollers 302 while moving the thrust plate 307 to the retracted position. Further, when a conveying position detecting sensor (not shown) detects that the first folded portion of the sheet S has reached the bottom of the additional folding unit 304, the conveying of the folding roller pair 305 is stopped. After that, an additional folding guide 313 holding a plurality of rotatable additional folding rollers 314 moves downward, and the first folding portion of the sheet S is sandwiched between the lower folding guide 311 and the additional folding rollers 314 to perform additional folding. I do. After that, the additional folding guide 313 moves in the front-rear direction, so that the entire first folding portion of the sheet S is additionally folded.

FIG. 8G shows a state immediately before the sheet S is further conveyed by the folding roller pair 105 and the Z-folding loop is eliminated and the sheet enters the folding roller pair.

FIG. 8(h) shows a state in which the second folding portion is formed by squeezing the loop and passing it through the pair of folding rollers, and additional folding is performed by the additional folding unit 304. FIG. When a conveying position detection sensor (not shown) detects that the second folding portion has come to the lower side of the additional folding unit, the conveying of the folding roller pair 305 is stopped. After that, an additional folding guide 313 holding a plurality of rotatable additional folding rollers 314 moves downward, and the first folding portion of the sheet S is sandwiched between the lower folding guide 311 and the additional folding rollers 314 to perform additional folding. I do. After that, the additional folding guide 313 moves in the front-rear direction to additionally fold the entire second folding portion of the sheet S. As shown in FIG.

After the additional folding process is completed over the entire second folding portion by the additional folding roller 314 and the lower folding guide 311, the additional folding unit 304 is retracted to a predetermined position, and the additional folding roller 314 and the lower folding guide 311 are closed. A folding portion conveying path 118 is formed between. Thereafter, the sheet is conveyed by the pair of folding rollers 305 and delivered to the carry-in port 30 of the sheet stacking device C from the downstream side of the folding portion conveying path 318 .

[Sheet stacking device]
The sheet stacking device C is connected to the downstream side of the folding device B connected to the image forming device A, and stores sheets that have been folded by the folding device B or discharged without being folded. S is received, and post-processing such as stapling and alignment processing is performed as necessary.

As shown in FIGS. 1 and 2, the sheet stacking device C has a sheet inlet 30 provided on one side of the device frame 20 and a single sheet or relatively thick sheet provided on the opposite outer side. An accumulating escape tray 22 is arranged. Below the escape tray 22, a first stacking tray 24 that can be raised and lowered is positioned for stacking end-face-stitched sheets and a relatively large number of sheets. Further, below the first stacking tray 24, a second stacking tray 26 for stacking saddle-stitched or folded sheets is provided. In the present invention, the term "end surface" refers to the surface around the edge of the sheet, that is, the front and back surfaces of the edge of the sheet.

A transport path 42 extending substantially linearly from the carry-in path 32 to the first processing tray exit 50 is arranged from the carry-in opening 30 of the sheet stacking device C. As shown in FIG. A punching unit 31 is provided in the carry-in path 32, and punches the end face of the sheet and, if necessary, the middle of the sheet in the conveying direction. A punch scrap box 31b for accumulating punch scraps generated during the punching process is detachably mounted on the apparatus frame 20 below the punch unit 31 across the carry-in path 32. As shown in FIG.

A carry-in roller 34 for conveying the sheet is arranged downstream of the punch unit 31 to convey the sheet at high speed. In the transport path 42 on the downstream side of the carry-in rollers 34, there are transport rollers 44 (reversible transport rollers 44 ( A first transport means) is provided. A sheet conveying path exit 46 is provided behind the conveying roller 44 .

An outlet roller 48 (second conveying means) that can rotate forward and backward is provided downstream of the conveying path exit 46 . The exit roller 48 switches back the sheet to convey the sheet to the first processing tray 54 , discharges the sheet straight to the first stacking tray 24 , or stacks the sheet on the first processing tray 54 and performs end face binding processing. The stack of sheets is discharged to the first stacking tray 24 .

At a branch position 36, the transport path 42 has an escape path 38 that guides sheets to the escape tray 22, and a stacker 84 that serves as a second tray for saddle-stitching and folding relatively long sheets (also serving as a second processing tray). ) and a branch route 70 that guides to ). At the branch position 36, there is a path switching gate for selecting whether the sheet is conveyed to the conveying path 42 as it is, conveyed to the escape path 38, or is switched back on the conveying path 42 and guided to the branch path 70. 37 is provided. The escape path 38 is provided with an escape roller 39 that conveys the sheet and an escape outlet roller 40 that discharges the sheet to the escape tray 22 .

A first processing tray 54 is provided below the transport path exit 46 of the transport path 42, and an end surface binding unit 60 for binding the end surfaces of the sheets temporarily stacked on the first processing tray 54 is positioned at the lower end side of the first processing tray 54. are doing. The end face binding portion 60 will be described later with reference to FIG.

[Saddle stitch part]
A relatively long sheet is once conveyed along the conveying path 42 in the direction of the first processing tray 54 , conveyed to the downstream side of the switching gate 37 , and then conveyed back to the branch path 70 to be conveyed from the branch outlet 76 . Stacked in the stacker 84 (second tray). As shown in FIG. 2, the branch outlet 76 is modified to urge the sheet to the left side in the drawing each time the sheet is conveyed from the branch outlet roller 74 to the stacker 84 to prevent the trailing edge of the preceding sheet from colliding with the leading edge of the next sheet. A flapper 78 is provided.

The stacker 84 is provided with a stopper 85 that defines the sheet loading position. The stopper 85 moves in the direction of the arrow in the figure by driving a moving belt stretched between an upper pulley 86 and a lower pulley 87 on the side of the stacker 84 by a stopper moving motor 85M. The position of the stopper 85 is the position where the rear end of the sheet can be changed by the change flapper 78 when the sheet is carried into the stacker 84, the position where the saddle stitching unit 82 saddle stitches the substantially center of the sheet in the conveying direction, and the position where the sheet is saddle stitched. The saddle-stitched position is pushed by the folding blade 94 reciprocating between the pair of folding rollers 92 to stop at the position where the bundle of sheets is folded in two. Saddle stitch alignment plates 81 are provided above and below the folding roller 92 to press both side edges of the sheet in the sheet width direction to align the sheet each time the sheet is carried into the stacker 84 .

The saddle-stitching section 80 is provided with an anvil 83 which is provided at a position opposite to which staples, for example, staples are driven by a driver in the saddle-stitching unit 82 to bend the legs of the staples. Since the saddle stitching unit 82 is already widely known, a description thereof will be omitted here. It may also be a mechanism in which the sheets are pasted together to form a bundle.

A bundle of sheets bound by the saddle stitching unit 82 is folded in two by a folding roller 92 and a folding blade 94 that pushes the sheet bundle into the folding roller 92, and a second folding roller 92 and a bundle discharging roller 96 positioned downstream of the folding roller 92 fold the sheet bundle into two. It is discharged to the stacking tray 26 . On the second stacking tray 26, a swingable pressure roller provided with a rotatable roller at the leading end for dropping the folded sheet bundle discharged with the back side thereof as the leading end side onto the second stacking tray 26. 102, and a pressing lever 104 for pressing from above so that the accumulated bundle of folded sheets does not spread. The presser roller 102 and the presser lever 104 reduce the deterioration of stacking performance due to the opening of the folded sheet bundle.

A further description of the branch position 36 and the end face binding portion 60 will be added with reference to FIG. As already explained, the carry-in path 32 in which the carry-in rollers 34 are arranged from the carry-in opening 30, the transport path 42 extending linearly from this in the direction of the first processing tray 54, and the escape path extending upward in the drawing from the transport path 42. 38 and a branch path 70 that bends downward to guide the sheets to the stacker 84 are shown. At the branch position 36, the sheet on the carry-in path 32 is guided to the escape path 38 or the conveying path 42, or the sheet conveyed switchback on the conveying path 42 is selectively positioned on the branch path 70 and guided. A flapper 37 is arranged.

In this embodiment, for example, as shown in FIG. 3, the escape path 38 is blocked at the solid line position to guide the sheet from the carry-in path 32 to the transport path 42, and at the dashed line position the carry-in path 32 A sheet conveyed from the outlet is guided to the escape route 38, and a sheet conveyed back through the conveying route 42 is guided to the branch route 70. FIG.

In the conveying path 42 , conveying rollers 44 are arranged immediately before a conveying path exit 46 which is the final end, and rotate in forward and reverse directions and are in contact with each other. That is, the sheet can be conveyed to the first processing tray 54 side by rotating in one direction while the conveying roller 44 is in pressure contact, and can be switchback conveyed in the opposite direction by rotating in the other direction.

This switchback conveying is performed by rotating the conveying roller 44 in the other direction after a sensor arranged immediately after the changing flapper 37 of the conveying path 42 detects the passage of the trailing edge of the sheet. At the time of rotation in the other direction, the change flapper 37 is moved to the position (broken line position in FIG. 3) blocking the carry-in path 32 . As a result, the sheet is conveyed to the branch path 70 and is taken over and conveyed by the branch roller 72. When the trailing edge of the sheet reaches a predetermined position, the branch roller 72 is stopped and the sheet is placed in the standby state in the branch path 70.

Outlet rollers 48 that reciprocate forwards and backwards and are separated from each other are arranged at the first processing tray exit 50 (the exit of the first processing tray 54 ) downstream of the conveying rollers 44 . The exit roller 48 is composed of an exit upper roller 48a and an exit lower roller 48b, which rotate in one direction while being pressed against each other, and cooperate with the conveying roller 44 to convey the sheet to the first stacking tray 24. Then, the sheet is conveyed to the branch path 70 by the other rotation. In addition, the exit roller 48 is also used when the sheets stacked and bundled on the first processing tray 54 are discharged to the first stacking tray 24 in cooperation with movement of a reference surface 57, which will be described later.

Next, stacking of sheets on the first processing tray 54 will be described. In the stacking on the first processing tray 54, the sheet discharged from the conveying roller 44 is conveyed to the right side in FIG. The transported sheet is transported by rotating the scraping roller 56 around which the belt 146 with projections is wound counterclockwise in the drawing. As a result of this transfer, the leading end of the sheet in the conveying direction comes into contact with the reference surface 57 serving as the binding reference on the other surface and stops. At this time, the scraping roller 56 slides on the sheet to prevent the leading edge of the sheet from buckling after coming into contact with the reference surface.

When the sheet is discharged from the conveying roller 44 , the sheet is sent to the reference surface 57 by the rotation of the exit roller 48 and the scraping roller, and stacked on the first processing tray 54 . Along with this stacking operation, the aligning plates 58 are brought into contact with each other in the sheet width direction to align the sheets in the center of the width direction of the first processing tray 54 . Such stacking and alignment are repeated until the specified number of sheets of a bundle is obtained. When the specified number of sheets is reached, the end surface binding unit 62 that moves the end surface of the sheet on the moving table 63 in the sheet width direction is moved to a desired binding position. This movement is guided by the moving pin 62b of the end face binding unit 62 being engaged with a grooved rail provided on the moving table 63 in the sheet width direction.

Since the binding process of the end face binding unit 62 is already known, a description thereof will be omitted. When the end face binding unit 62 stops at a designated binding position, the end face binding motor 62M is rotationally driven to move a driver (not shown). Staples are driven into a bundle of sheets, and the driven staples are bent by an anvil for binding. This binding process is performed at a plurality of positions on the edge faces of the corners of the sheets and on the edge faces in the width direction.

The sheet bundle bound by the end-face binding unit 62 is moved counterclockwise in the figure by a reference plane moving belt 64 stretched over a right pulley 65 and a left pulley 66 under the first processing tray 54, and is moved to the reference plane. As the reference surface 57 connected to the moving belt 64 moves leftward in the drawing, the binding edge side of the sheet bundle is pushed out toward the first stacking tray 24 . Along with this pushing, the bound sheet bundle is pressed from the front and back by the exit roller 48 arranged at the exit of the first processing tray 54, and the bound sheet bundle on the first stacking tray 24 is discharged by rotating clockwise. do.

The first stacking tray 24 for stacking sheet bundles will be described. As shown in FIG. 3 , the first stacking tray 24 is arranged with substantially the same inclination angle as the first processing tray 54 . 44, the individual sheets ejected by exit rollers 48 are also accumulated. On the bottom side of the first stacking tray 24, a second moving means for moving up and down the first stacking tray 24, an elevating motor 24M, is provided. The elevating pinion 109 is engaged with an elevating rack 107 provided vertically fixed inside the standing surface 28 of the device frame 20 . Also, although not shown, the first stacking tray 24 is vertically guided by an elevating rail provided on the standing surface 28 of the first stacking tray 24 . Further, a second control means for controlling a second moving means for moving up and down the first stacking tray 24 is provided.

The position of the first stacking tray 24 or the position of the sheets stacked on the first stacking tray 24 is detected by a sheet surface sensor 24S provided on the upright side. When the first stacking tray 24 is detected by the sheet surface sensor 24S, the lift motor 24M is driven to rotate the lift pinion 109 and descend. In the state shown in FIG. 3, the upper surface of the first stacking tray 24 is detected by the paper surface sensor 24S, and the sheet bundle is received by slightly lowering from here. Therefore, the upper surface of the exit position from the first processing tray 54 and the upper surface of the first stacking tray 24 are positioned with a step.

[Rotational drive of upper conveying roller 44a]
Next, with reference to FIG. 4, the rotational drive and contact/separation configuration of the conveying roller 44 and the exit roller 48 will be described. First, the transport roller 44 consisting of the upper transport roller 44a and the lower transport roller 44b is driven by a transport roller motor 44M. The conveying roller motor 44M is composed of a hybrid stepping motor, and is provided with a speed detection sensor 44S for detecting the rotational speed of the motor shaft. The drive of the conveying roller motor 44M is transmitted to the arm gear 126 via the transmission gears 120 and 122 and the transmission belt 124. As shown in FIG. Drive from the arm gear 126 is transmitted by a transmission belt 128 to the upper roller shaft 44uj of the upper conveying roller 44a supported by the conveying roller support arm 136 .

The upper conveying roller 44a is attached so as to rotate around the shaft of the arm gear 126 so as to come into contact with and separate from the fixed lower conveying roller 44b. This contact and separation is performed by a conveying roller moving arm 130 having a rear sector gear attached to the shaft of the arm gear 126 and having a spring 134 attached to the end of the moving arm on the tip side to bias the upper conveying roller 44a. . That is, by driving the conveying roller moving arm motor 130M engaged with the rear fan-shaped gear in the forward and reverse directions, it rotates in one direction in the release direction of arrow O, and rotates in the other direction to press the lower conveying roller 44b in the direction of arrow C. Moves in the pressing direction. The transport roller moving arm motor 130M is also a stepping motor, and the position of the transport roller moving arm 130 is detected by a transport roller moving arm sensor 130S.

The rotation of the lower conveying roller 44b is performed by transmitting the drive of the conveying roller motor 44M via the transmission gear 120 and the transmission belt 138 to the receiving gear 142 fixed to the lower conveying roller shaft 44sj. The drive from the receiving gear 142 rotates the scraping roller 56 via a gear 144 with a one-way clutch and a belt 146 with protrusions that also serves as a transmission belt. Since the pick-up roller 56 is transmitted through the gear 144 with a one-way clutch, as already explained, even if the receiving gear 142 rotates forward and backward, it rotates only in the direction of the solid arrow in FIG. Transfer only in the direction of the reference surface 57 of the tray 54 . The drive of the conveying roller motor 44M is also transmitted via the transmission gear 120 and the transmission belt 148 to the lower branch roller shaft 72sj of the lower branch roller 72b of the branch roller 72 that conveys the sheet in the branch path 70. FIG.

According to the forward and reverse rotation of the conveying roller motor 44M, the conveying roller 44 and the branching roller 72 move in one direction of the solid line arrow and the other direction of the broken line arrow (switchback direction). It rotates in the direction of the reference plane 57 in the direction of the solid arrow. Further, the conveying roller motor 44M has a speed of about 1100 mm/s when conveying the sheet to the first processing tray 54 side, and about 1100 mm/s or It can be arbitrarily set so that the sheet can be conveyed at a lower speed of about 600 mm/s. Since this transport speed is the rotation set speed from the start, the average speed will be lower than this set speed value. It is variable depending on the transport mode, etc. This speed setting will be described later.

An exit roller motor 48M drives the exit rollers 48 consisting of an exit upper roller 48a and an exit lower roller 48b. The exit roller motor 48M is also composed of a hybrid type stepping motor, and a speed detection sensor 48S for detecting the rotation speed of the motor shaft is also arranged. The drive of the exit roller motor 48M is transmitted to the exit arm gear 156 via the transmission gears 150, 152 and the transmission belt 154. Drive from the exit arm gear 156 is transmitted by a transmission belt 158 to the exit upper roller shaft of the exit upper roller 48 a supported by the exit roller support arm 166 .

The upper exit roller 48a is mounted to rotate around the axis of the exit arm gear 156 so as to come into contact with and separate from the fixed lower exit roller 48b. This contact/separation is effected by an exit roller moving arm 160 having a rear fan-shaped gear attached to the shaft of the exit arm gear 156 and having a spring 164 attached to the end of the movement arm on the tip side to bias the upper exit roller 48a. done. By driving the exit roller moving arm motor 160M engaged with the rear fan-shaped gear in the forward and reverse directions, one-way rotation in the release direction of arrow O and the other direction rotation in the direction of arrow C press contact with the lower exit roller 48b of arrow C. Moves in the pressing direction. The exit roller moving arm motor 160M is also composed of a stepping motor, and the position of the exit roller moving arm 160 is detected by an exit roller moving arm sensor 160S. The rotation of the exit lower roller 48b is performed by transmitting the drive of the exit roller motor 48M through the transmission gear 150 and the transmission belt 168 to the receiving gear 169 provided on the exit lower roller shaft 48sj.

With the above configuration, according to the forward and reverse rotation of the exit roller motor 48M, the exit roller 48 moves in one direction indicated by the solid-line arrow and in the other direction indicated by the broken-line arrow (after the sheet is discharged from the conveying roller 44, the first processing tray 54 is rotated). up) in the switchback direction to the reference plane 57). The exit roller motor 48M performs the first processing at a speed of about 1100 mm/s in the case of taking over the conveying from the conveying roller 44, and at a speed of about 600 mm/s in the case of taking over the switchback conveying in the direction of the reference surface. When the sheet bundle on the tray 54 is discharged to the first stacking tray 24 in cooperation with the movement of the reference plane 57, it can be set so that the sheets can be conveyed at a speed of about 300 mm/s. That is, the exit roller motor 48M can set the speed in the range of approximately 1100 mm/s to approximately 300 mm/s. In this embodiment, when the sheet is conveyed by the conveying rollers 44, such as when the sheet is conveyed by the conveying roller 44 during switchback conveying in standby conveying, the driving motors are separate and interlocking is difficult. It is located at a spaced position released from the roller 48b.

The mechanism for raising and lowering the first stacking tray 24 has already been described with reference to FIG. The elevation position is set by detecting the paper surface of the paper surface sensor 24S or the upper surface of the first stacking tray 24. FIG. Detection by the paper surface sensor 24S is performed by detecting a sensor flag 24f whose one end is rotatably supported. An empty sensor 25 for detecting whether or not a sheet is placed is provided on the placement surface of the first stacking tray 24 . Therefore, when the empty sensor 25 is ON, the paper surface sensor 24S detects the upper surface of the sheet, and when it is OFF, the height of the mounting surface on which no sheet is placed is detected. It means that

The elevation position of the first stacking tray 24 is set so that when the sheet bundle is discharged from the first processing tray 54, the loading surface or the paper surface is positioned at the sheet receiving position at the distance L1+L2 shown in FIG. There is. When the sheets are discharged one by one, the mounting surface or the paper surface is set to be positioned at the guide position 24Sh at the distance L1 that shortens the sheet drop range. When the sheet to be switchback-conveyed by the conveying rollers 44 is short, or when the switchback conveyance is to wait in the branch path 70 for end face binding, the leading edge of the sheet to be switched back is placed on the first stacking tray 24 . In order not to touch the sheet and the mounting table which are being held, it is lowered to a separation position 24SL of a distance of L1+L2+L3. Furthermore, when the sheet to be switchback-conveyed by the conveying rollers 44 is long, or when the switchback conveyance is for conveying to a branch path for saddle stitching, it is possible to suppress bending and fluttering of the leading edge of the switchback-conveyed sheet. In order to guide the sheet to , the lift setting is also performed so that the placement surface or the paper surface is positioned at the guide position 24Sh of the L1 distance that shortens the step range.

Standby conveyance in which the sheet is switched back and waited on the branch path 70 for the above-described end face binding will be described. When the first processing tray 54 is bound by the end-face binding unit 62 , the sheets formed by the image forming apparatus A and Z-folded by the sheet folding apparatus B are ejected at a high speed or the sheet interval is short. It is necessary to prevent the next sheet from being carried in before the end face binding process of the sheet bundle to be processed is completed. For this reason, the first or second sheet conveyed to the conveying path 42 via the carry-in path 32 is once switched back on the conveying path 42, and the switch-back-conveyed sheet is held in the branch path 70. It is practiced to leave and wait. Then, the sheet waiting in the branch path 70 is let out so as to be overlapped with the next second or third sheet to secure the interval time between the sheet bundles.

Here, one or more sheets that have been switchback-conveyed from the conveying path 42 to the branch path 70 are held in the branch path 70 to wait, and then fed out and conveyed together with the sheet next to the waiting sheet is referred to as "standby conveying". defined as Most of the sheets for edge-face binding to be conveyed in standby are relatively short sheets in the conveying direction, for example, A4, B5, and letter size sheets. Therefore, the switchback conveyance for the standby conveyance of these sheets is performed without protruding significantly to the downstream side of the first processing tray 54, and the sheet hardly bends during the standby conveyance. Even if it is bent to some extent, the distance to the first processing tray 54 is relatively short, so the bending is easily corrected by the aligning operation of the aligning plate 58 . The completion of the end face binding process is not only the completion of the operation of discharging the sheet bundle from the first processing tray 54 to the first stacking tray 24, but also the initial setting operation of the alignment plate 58 on the first processing tray 54, , returning the reference surface moving belt 64 to its initial position, or setting each mechanism to its initial position to accept the next sheet.

The non-Z-folded sheets discharged from the image forming apparatus A, passed through the folding processing device B without folding processing, and carried into the sheet stacking device C are stacked on the first processing tray 54 to form a sheet bundle, and are subjected to binding processing. The operation of discharging to the first stacking tray 24 after loading will be described with reference to FIGS. 9 and 10. FIG.

FIG. 9A shows a state in which the unZ-folded sheet S conveyed from the folding device B is received at the inlet 30 and conveyed by the carry-in rollers 34 . The non-Z-folded sheet S advances along the transport path 42 from the leading edge side, passes over the transport path sensor 42S, and is further transported. The exit roller 48 receives the sheet S in a state in which the upper roller 48a is retracted upward away from the lower roller 48b.

FIG. 9B shows a state in which the upper roller 48a of the outlet roller 48 descends, the sheet S is nipped between the upper roller 48a and the lower roller 48b, and the sheet S is further conveyed downstream. The leading edge of the sheet S is further conveyed over the exit roller 48 and conveyed further downstream above the first stacking tray 24 . At this time, the height position of the first stacking tray 24 is set to the first height position, which is the normal receiving height for receiving the sheets from the exit rollers 48 .

9C, the exit roller 48 continues to rotate forward to convey the sheet S further downstream, and reverses when the trailing edge of the sheet S passes through the exit 46 of the conveying path 42. In FIG. As a result, the trailing edge of the sheet S passes through the scraping roller 56, and as shown in FIG. 9C, the exit roller 48 is stopped in a state where it abuts against the reference surface 57 of the first processing tray 54. As shown in FIG. At this time, the transport of the next sheet S has already started, and the leading edge of the sheet S passes through the carry-in path 32 from the carry-in entrance 30 by the carry-in roller 34, passes the carry-path sensor 42S, and is carried downstream along the carry-path 42. It is

FIG. 10D shows a state in which a plurality of sheets S are stacked in the first processing tray 54 with their trailing edges abutted against the reference surface 57 and positioned. A predetermined number of sheets S stacked on the first processing tray 54 are bundled and bound by the end face binding unit 62 . The binding process is performed by moving the end face binding unit 62 to a predetermined binding position and driving the end face binding motor 62M (not shown).

FIG. 10E shows a state in which the sheet bundle that has been bound in FIG. As shown in FIG. 10E, the leading edge of the sheet bundle is placed on the stacking surface of the first stacking tray 24 or the upper surface of the already stacked sheets (sheet bundle) already stacked on the first stacking tray 24, and sent downstream. Thereafter, the trailing edge of the sheet bundle is ejected onto the first stacking tray 24 by kicking out the trailing edge of the sheet bundle at a predetermined paper ejection speed, and the trailing edge of the sheet bundle is aligned with the standing surface 28 of the apparatus frame 20. loaded.

The Z-folded sheets discharged from the image forming apparatus A, folded by the folding device B, and conveyed to the sheet stacking device C are stacked on the first processing tray 54 to form a sheet bundle, which is then bound. 11 and 12, the operation of discharging to the stacking tray 24 will be described.

In FIG. 11A, the sheet S Z-folded by the folding processing device B is recognized as a Z-folded sheet by the Z-fold recognition means, and then received at the carry-in port 30 and carried in. A state in which the sheet is conveyed by the rollers 34 is shown. In this embodiment, the Z-fold recognizing means is composed of a receiving section that receives information on the sheet S sent from the image forming apparatus A, and includes information indicating that the sheet S will be Z-folded by the folding processing apparatus B. If so, it is recognized as a Z-folded sheet. The Z-folded sheet S advances along the conveying path 42 from the leading end side of the Z-folded sheet, passes over the conveying path sensor 42S, and is further conveyed. The exit roller 48 receives the Z-folded sheet S without nipping in a state in which the upper roller 48a is retracted upward away from the lower roller 48b.

FIG. 11(b) shows a state in which the upper roller 48a of the exit roller 48 has come down, the upper roller 48a and the lower roller 48b are in a nip state, and the Z-folded sheet S is conveyed further downstream. . The leading edge of the Z-folded sheet S is further conveyed over the exit roller 48 and conveyed further downstream above the first stacking tray 24 . At this time, since the Z-folded sheet S does not have a member or structure for supporting the leading edge portion extending upward from the exit roller 48 above the first stacking tray 24, the Z-folded sheet S is in a cantilevered state supported by the exit roller 48. . Therefore, in the leading end portion of the Z-folded sheet S, the lower sheet portion that overlaps with the Z-folded sheet may hang slightly open depending on the properties and type of the sheet, the image forming state, and the environment such as temperature and humidity. .

Therefore, as shown in FIG. 11C, while the exit roller 48 is conveying the Z-folded sheet S further downstream, the first stacking tray 24 is moved to the second height position higher than the first height position. height position. As a result, the portion of the sheet that hangs below the leading end of the Z-folded sheet S is lifted by contact with the upper surface of the first stacking tray 24, so that the hanging state of the sheet can be eliminated. can.

The exit roller 48 continues to rotate forward to convey the Z-folded sheet S further downstream, and reverses when the trailing edge of the Z-folded sheet S passes through the exit 46 of the conveying path 42 . As a result, the trailing edge of the Z-folded sheet S passes through the raking roller 56 and hits the reference surface 57 of the first processing tray 54 as shown in FIG. At this time, the transport of the next Z-folded sheet S has already started, and the leading edge of the Z-folded sheet S has passed through the carry-in path 32 from the carry-in port 30, passed the transport path sensor 42S, and is transported downstream along the transport path 42. .

As illustrated, the Z-folded sheet S is nipped and held by the exit roller 48 at the leading end portion of the Z-folded sheet S, which is folded in three. Since the first stacking tray 24 is stopped at the second height position, the lower sheet portion of the leading end side portion of the Z-folded sheet S, which was hanging down in FIG. maintained in good condition.

FIG. 12E shows a state in which a plurality of Z-folded sheets S are stacked in the first processing tray 54 with their trailing edges abutting against the reference surface 57 and positioned. The predetermined number of Z-folded sheets S stacked on the first processing tray 54 in this way are bundled and bound by the end surface binding unit 62 . The binding process is performed by moving the end face binding unit 62 to a predetermined binding position and driving the end face binding motor 62M.

In FIG. 12E, all the sheets of the sheet bundle bound by the edge binding unit 62 are Z-fold sheets. In another embodiment, the sheet bundle stacked in the first processing tray 54 can be composed of Z-folded sheets and non-Z-folded sheets. In this case as well, the tip side portion of the Z-folded sheet contained therein may hang downward as in FIG. 11(b). By raising it to the position, it is possible to eliminate the sagging of the leading end side portion of the Z-folded sheet.

FIG. 12(f) shows a state in which the Z-folded sheet bundle that has been bound in FIG. The Z-folded sheet at the bottom of the bundle lands on the stacking surface of the first stacking tray 24 or the upper surface of the already-stacked sheets from the leading edge side portion folded in three, and is further downstream while being in contact with the stacking surface or the upper surface. transported to Since the first stacking tray 24 is at the second height position, it is possible to prevent the leading edge of the lowest sheet of the Z-folded sheet bundle from hanging down and being transported while hitting the stacking surface or upper surface, resulting in so-called curling. can be done.

The first stacking tray 24 is lowered from the second height position to the first height position in accordance with the operation of discharging the Z-folded sheet bundle by the exit rollers 48 . This reduces the frictional resistance generated between the lower surface of the discharged Z-folded sheet bundle and the stacking surface of the first stacking tray 24 or the upper surface of the already-stacked sheets (sheet bundle), ensuring smooth discharge, When there are already stacked sheets (sheet bundle) on the first stacking tray 24, the risk of pushing out the uppermost sheet (sheet bundle) on the first stacking tray 24 to the downstream side is eliminated. By raising and lowering the first stacking tray 24 in this way, when the Z-folded sheet bundle is discharged to the first stacking tray 24, curling of the leading edge and pushing out of already stacked sheets are prevented, thereby improving the stackability and alignment of the sheets. can be improved.

FIG. 12G shows a state in which the Z-folded sheet bundle is discharged onto the first stacking tray 24. FIG. At this time, the first stacking tray 24 is lowered to the first height position and stopped as described above, and as shown in FIG. 48 becomes acceptable.

A series of operations of the first stacking tray 24 when discharging the Z-folded sheet bundle from the exit roller 48 as described above with reference to FIGS. 9 to 12 will be described with reference to the flowchart of FIG.

First, when the image forming apparatus A starts discharging a sheet on which an image has been formed (St1), sheet information regarding the sheet is output as a signal from the image forming apparatus A and received by the post-processing apparatus C (St2). The sheet information includes whether or not the sheet discharged in step St1 is to be Z-folded by the folding device B, sheet size, basis weight, and the like. As will be described below, the height position of the first stacking tray 24 is set depending on whether or not the sheet from the image forming apparatus A is Z-folded based on the sheet information.

If the signal does not include Z-folding of the sheet (No in St3), the first stacking tray 24 is set to the first height position which is the standard sheet receiving height (St4 ). If the signal includes Z-folding of the sheet (Yes in St3), further based on the signal from the image forming apparatus A, it is determined whether or not the basis weight of the sheet exceeds a certain threshold. Determine (St5).

As a result, when the basis weight of the sheet is equal to or greater than the certain threshold value (No in St5), the first stacking tray 24 is moved to a second height position higher than the first height position ( St9). On the other hand, if the basis weight of the sheet is less than the certain threshold value (Yes in St5), the first stacking tray 24 is moved to a third height position higher than the second height position ( St10). If the basis weight of the sheet is small, the leading edge of the sheet tends to be curled. Therefore, in step St5, the constant threshold value of the basis weight of the sheet is set to, for example, 80 g/m ² , which corresponds to the basis weight of recycled paper. can do.

If the sheet is not Z-folded in step St3 (No), the predetermined number of sheets are discharged to the processing tray 54 while the first stacking tray 24 is at the first height position. (Yes in St6 and St7), and after being bound into a sheet bundle by the end-face binding unit 62, the sheet bundle is discharged to the first stacking tray 24 by the exit roller 48 (St8). In this case, the first stacking tray 24 is maintained at the first height position during the series of operations described above.

If the sheet includes the Z-folding process in step St3 (Yes), the first stacking tray 24 is positioned at the second height position or the third height position depending on the basis weight of the sheet. , a predetermined number of Z-folded sheets are discharged to the processing tray 54 (Yes in St11 and St12), and the edge binding unit 62 binds them into a Z-folded sheet bundle. After that, the Z-folded sheet bundle is discharged to the first stacking tray 24 by the exit roller 48 while the first stacking tray 24 is being moved to the first height position (St13) (St14).

The degree of sagging at the leading end of the Z-folded sheet bundle when discharged from the exit roller 48 may vary depending on the number and/or ratio of Z-folded sheets included in the sheet bundle formed on the first processing tray 54. , the height position of the first stacking tray 24 can be adjusted more finely stepwise or continuously in addition to or instead of the first, second and third height positions. As a result, it is possible to more effectively prevent the leading edge of the Z-folded sheet bundle from curling when discharged onto the first stacking tray 24, thereby improving the stackability and alignment of the sheets. The number and/or ratio of Z-folded sheets included in the sheet bundle can be determined based on the sheet information from the image forming apparatus A or by counting the number of sheets carried into the first processing tray 54. can be done.

In another embodiment, it is possible to set a position higher than the second height position using whether or not the number of Z-folded sheets stacked on the first processing tray 54 exceeds a predetermined number as a threshold.

Also, the degree of sagging of the leading end portion of the Z-folded sheet may change depending on how long the Z-folded sheet S is stored in the first processing tray 54 . Therefore, by counting the time that the Z-folded sheet S is stored in the first processing tray 54 and adjusting the height position of the first stacking tray 24 according to that time, It is possible to more effectively prevent the leading edge of the Z-folded sheet from curling during discharge, thereby improving the stackability and alignment of the sheet.

The present invention is not limited to the above-described embodiments, and various modifications can be made to the above-described embodiments without departing from the technical scope thereof. All technical matters contained in are covered by the present invention. In addition, although the above-described embodiments show preferred examples of the present invention, those skilled in the art can make various alternatives, modifications, variations, or improvements based on the disclosure of this specification. can be implemented and are within the scope of the claims of the present application.

A Image forming apparatus B Folding device C Sheet stacking device 20 Device frame 24 First stacking tray 28 Standing surface 30 Carry-in entrance 31 Punch unit 32 Carry-in path 42 Conveyance path 48 Outlet roller 54 First processing tray 60 End surface binding section

Claims (8)

a loading means for loading sheets;
a discharging means for discharging the sheet conveyed in a predetermined conveying direction to the stacking means;
and a lifting means for lifting and lowering the loading means,
When the sheet to be discharged to the stacking means by the discharging means is a Z-folded sheet that has been Z-folded, the lifting means is configured to perform Z-folding before the Z-folded sheet is discharged to the stacking means by the discharging means. The stacking means is moved to a second height position higher than the first height position for discharging the unfolded non-Z-folded sheet, and the discharge means moves the Z-folded sheet to the stacking means. A sheet stacking device that lowers the stacking means from the second height position in response to the sheet stacking operation. a conveying path for conveying the sheet in the predetermined conveying direction;
a processing tray for forming a sheet bundle with a plurality of sheets carried in from the conveying path;
The discharging means discharges the sheet bundle from the processing tray to the stacking means,
When the sheet bundle discharged from the processing tray by the discharging means includes Z-folded sheets, the lifting means is higher than the first height position before the sheet bundle is discharged by the discharging means. moving the stacking means to a third height position, and lowering the stacking means from the third height position in response to the operation of discharging the sheet bundle to the stacking means by the discharging means; The sheet stacking device according to claim 1. further comprising Z-folded sheet recognition means for determining whether the sheet conveyed in the predetermined conveying direction is a Z-folded sheet;
3. The sheet stacking apparatus according to claim 1, wherein said lifting means lifts and lowers said stacking means based on the determination by said Z-folded sheet recognition means. further comprising basis weight recognition means for determining the basis weight of the Z-folded sheet conveyed in the predetermined conveyance direction;
If the basis weight of the Z-folded sheet is smaller than a predetermined basis weight value based on the determination by the basis weight recognition means, the lifting means moves the height of the stacking means to be moved before the discharging operation of the discharging means. The position is higher than the second height position when the Z-folded sheet is discharged as a single sheet, and is higher than the third height position when the Z-folded sheet is discharged as a sheet bundle. 4. The sheet stacking device according to any one of claims 1 to 3, which is adjusted. further comprising Z-folded sheet number recognition means for determining the number of Z-folded sheets included in one sheet bundle formed on the processing tray;
Based on the determination by the Z-folded sheet number recognizing means, the lifting means adjusts the number of Z-folded sheets included in the sheet bundle discharged from the processing tray by the discharging means before the discharging operation of the discharging means. 3. The sheet stacking apparatus according to claim 2, wherein the height position of said stacking means to be moved is adjusted from said third height position. further comprising processing time detection means for measuring the time from when the first Z-folded sheet is carried into the processing tray to when it is discharged as a sheet bundle;
The lifting means adjusts the height position of the loading means to be moved before the discharging operation of the discharging means to the third height according to the measured time based on the measurement result of the processing time detecting means. 6. The sheet stacking device according to claim 2, wherein adjustment is made from a raised position. A sheet stacking device according to any one of claims 1 to 6;
an image forming apparatus that discharges a sheet on which an image has been formed;
an image forming system, comprising: a folding device that Z-folds a sheet from the image forming device and supplies the sheet to the sheet stacking device. The elevating means of the sheet stacking device determines whether or not the sheet discharged to the stacking means by the discharge means is a Z-fold sheet based on sheet information input from the image forming apparatus to the sheet stacking device. 8. The imaging system of claim 7.

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