JP6831444B2 - Post-processing device and image formation system equipped with it - Google Patents

Description

The present invention relates to a post-processing apparatus that collects and post-processes sheets sent from an image forming apparatus, and relates to an improvement of a transport system that does not stop the image forming process on the upstream side during the operation of the post-processing.

Generally, this type of post-processing system is widely known as a system in which an image is formed on a sheet by an image forming apparatus on the upstream side, and the sheet is integrated for each part by an post-processing device on the downstream side to perform bookbinding or other post-processing. Has been done. In such a system, it is required from the operating efficiency of the system that an image forming apparatus on the upstream side continuously forms an image and post-processing is performed on the downstream side according to the processing speed.

Therefore, the sheets (bundles) that have been aligned and accumulated in the post-processing device are temporarily retained in the middle of the route during the post-processing such as bookbinding, and the subsequent sheets sent from the upstream side are temporarily retained in the middle of the route, and when the post-processing operation is completed, A transport system that feeds the stagnant sheet to the post-processing unit is adopted.

For example, Patent Document 1 includes post-processing including a straight path for guiding a sheet sent from an image forming apparatus to a first processing unit and a switchback path for branching from this path and guiding the sheet to a second processing unit. The device is disclosed.

According to Patent Document 1, the succeeding sheet sent from the upstream side during the processing operation of the first processing unit is retained in the switchback path guided to the second processing unit, and the processing operation of the second processing unit is performed. It has been proposed that the subsequent sheet sent from the upstream side stay in the straight path.

Then, the image forming apparatus on the upstream side forms an image on the sheet at a predetermined timing regardless of the post-processing operation on the downstream side and carries it out from the paper ejection port. When the post-processing apparatus receives this sheet and the post-processing mode is the first processing unit, the post-processing unit causes the sheet to stay in the switchback path that guides the sheet to the second processing unit, and the post-processing mode is the second processing unit. Occasionally, the sheet is retained in a straight path that guides the sheet to the first processing unit. Then, after the job in each processing unit is completed, the retention sheet is sent to the processing unit to perform the subsequent processing.

Japanese Patent No. 5248785

The productivity of sheet post-treatment is improved by stacking and retaining the plurality of supplied sheets and discharging the plurality of sheets that have been stacked and retained one by one to the accumulating portion at arbitrary intervals.

In order to solve the above problems, the present invention press-holds and retains a sheet received from a sheet carry-in port on at least one of a first paper discharge roller pair and a second transfer roller pair in a part of the transfer path. The stagnant sheet and the succeeding sheet received from the carry-in port are overlapped in a bundle to form a stagnant sheet bundle, and the stagnant sheet and the succeeding sheet from the stagnant sheet bundle are separately discharged as a second sheet. It is characterized by discharging from the mouth to the second accumulation part.

Here, the control means for controlling the transfer of the sheets sent from the carry-in port to each accumulation unit is the first to stack the retained sheets in advance of the succeeding sheets by a predetermined amount in the reverse transfer direction when generating the accumulated sheet bundle. 1 Controls the paper ejection roller pair and the second transport roller pair.

Then, the first paper ejection roller pair is configured to be pressure-welded and separated, and the control means causes the first paper ejection roller pair to be ejected when the sheet received from the carry-in port is discharged to the first integrated portion. When the stagnant sheet bundle is pressure-welded and discharged to the second integrated portion, the first paper discharge roller pair, the second transport roller pair, and the third discharge roller pair are separated from each other in order to separate the first paper discharge roller pair. Control a pair of paper rollers.

In the post-treatment apparatus according to the present invention, a plurality of supplied sheets are temporarily stacked and retained, and the retained sheets are supplied one by one to the accumulating portion at arbitrary intervals. Enables efficient post-processing.

Explanatory drawing of the whole structure of the image formation system which concerns on this invention. The configuration explanatory view of the after-processing apparatus in the system of FIG. FIG. 2 is a configuration explanatory view of a first post-processing unit in the post-processing device of FIG. FIG. 2 is a configuration explanatory view of a second post-processing unit in the post-processing device of FIG. The explanatory view which shows the transport state of the sheet in the post-processing apparatus of FIG. (A) is an explanatory diagram of a state in which the sheet retained in the path buffer unit is transported to the post-processing unit, and (b) is an explanatory diagram of a mechanism for transferring the buffer sheet to the second post-processing unit. It is explanatory drawing of the operation state which transfers a buffer sheet to a 1st post-processing section, (a) is a state which holds a sheet in a buffer section, (b) is a state which holds the retained sheet from a buffer section, and is a 1st post-processing section. Indicates the state of transportation toward. It is explanatory drawing of the operation state which transfers a buffer sheet to a 1st post-processing part, (a) is a state which positions a buffer sheet at a processing position on a processing tray, and (b) abuts a buffer sheet against a regulation stopper. Indicates the state. It is explanatory drawing of the operation state which transfers a buffer sheet to a 2nd post-processing section, (a) is a state which holds a sheet in a buffer section, (b) is a state which holds a stayed sheet from a buffer section, a 2nd post-processing section. Indicates the initial state of transfer to. It is explanatory drawing of the operation state which transfers a buffer sheet to a 2nd post-processing section, and is explanatory drawing which shows the state which carries the first sheet from a buffer section into a 2nd post-processing section. It is explanatory drawing of the operation state which transfers a buffer sheet to a 2nd post-processing section, and is explanatory drawing which shows the state which carries the last sheet from a buffer section into a 2nd post-processing section. The explanatory view of the control structure in the image formation system of FIG. The flowchart which shows the procedure of the post-processing operation (the first post-processing mode) in the image formation system of FIG. The flowchart which shows the procedure of the post-processing operation (second post-processing mode) in the image formation system of FIG.

The present invention will be described in detail below based on the preferred embodiments shown. The image forming system shown in FIG. 1 is composed of an image forming apparatus A for forming an image on a sheet and a post-processing device B for post-processing (finishing) the image-formed sheet. In this image forming system, a host device (computer or the like) that is networked on the upstream side of the image forming device A and creates image data is arranged. Hereinafter, the image forming apparatus A and the post-processing apparatus B will be described in this order.

[Image forming device]
The image forming apparatus A is arranged on the upstream side of the post-processing apparatus B, forms an image on the sheet, and sends the image from the paper ejection port 21 to the post-processing apparatus B on the downstream side. The illustrated image forming apparatus A includes a paper feeding unit 11, an image forming unit 13, a paper ejection unit 19, and a data processing unit 18 in the apparatus housing 10.

The paper feed unit 11 includes paper feed stackers 12a, 12b, and 12c (paper feed cassettes) for forming images, and feeds the sheets of the size selected by the operator one by one to the image forming unit 13 on the downstream side.

The image forming unit 13 forms an image with the image data specified in the sheet of the size selected and fed from the paper feeding unit 11. As the image forming mechanism, various image forming mechanisms such as the illustrated electrostatic printing mechanism, inkjet printing mechanism, transfer ribbon printing mechanism, thermal printing mechanism, and offset printing mechanism can be adopted.

Explaining the illustrated electrostatic printing mechanism, a latent image is formed on the photoconductor drum 14 by an optical beam (light emitter) 15, and toner ink is adhered by a developer 16 to form an image on the drum surface. Then, the image is transferred by the charger 17 to the sheet sent from the paper feed unit 11. The paper ejection unit 19 heats the sheet sent from the charger 17 to fix the image, and transfers the image from the paper ejection path 20 to the paper ejection port 21. A duplex path 22 is connected to the paper ejection port 21, and the transport direction of the sheet carried out from the paper ejection port 21 is reversed (switchback transport), the sheet is flipped upside down, and the sheet is fed to the image forming unit 13 again. Then, after forming an image on the back surface side of the sheet, the image is carried out from the paper ejection port 21.

FIG. 23 is a scanner unit, which is a platen 24 for setting a document, a reading carriage 25 for scanning a document on the platen and reading an image, and an image for transferring the read image data to a data processing unit 18 of an image forming apparatus A. The processing unit 26 is provided.

FIG. 27 is a feeder unit, and the original sheets set on the paper feed stacker 28 are separated one by one and fed to the platen 24, and the scanned original sheet is stored in the paper discharge stacker 29.

[Configuration of aftertreatment device]
The post-processing device B connected to the image-forming device A described above is a "first post-processing mode" in which image-formed sheets are collected in a bundle for each part (group) and bound, or in a bundle. In the "second post-processing mode" in which the folding process is performed, either post-processing is performed and the image is stored in the storage portion on the downstream side. The system shown in the figure further includes a "third post-processing mode (printout mode)" in which the image-formed sheet is stored in the storage portion on the downstream side.

Therefore, as shown in FIG. 2, the post-processing apparatus B provides the casing 30 with a first post-processing unit (first integrated unit; the same applies hereinafter) 35 for executing the first post-processing mode and a second post-processing mode. It is provided with a second post-processing unit (second integration unit; the same applies hereinafter) 49 for execution. Then, the sheets are distributed and conveyed from the transfer path 32 having the carry-in port 31 connected to the main body paper ejection port 21 to the first post-processing unit 35 and the second post-processing unit 49.

[Transport route configuration]
The transport route 32 is composed of a straight route 33 and a branch route 34. The branch route 34 is branched from the straight route 33 at the route branch portion 32a (hereinafter referred to as “branch portion”), and is configured to distribute the sheet carried in from the carry-in inlet 31 into the straight route direction and the branch route direction. Therefore, the route switching means 44 is arranged in the branch portion 32a, and guides the sheet to each route paper ejection port by a signal from the control means 76 described later.

The illustrated straight path 33 is composed of a substantially straight path in which the carry-in inlet 31 is located on one side surface (right side wall) of the casing 30 and the path output port 33a is located on the opposite side surface (left side wall). That is, as shown in FIG. 2, the straight path 33 is configured by a substantially straight path (which may be curved) that crosses the housing 30 in the horizontal direction, and is referred to as a path output port 33a (hereinafter referred to as “first output port”). The first post-processing unit 35 is arranged on the downstream side of (referred to as).

The branch path 34 is arranged in a direction intersecting the straight path 33, and the branch path 34 is arranged in the housing 30 in a substantially vertical direction with respect to the substantially horizontal straight path 33. As shown in FIG. 2, the branch path 34 branches from the horizontal straight path 33 and guides the sheet in the vertical direction, and the second rear from the path discharge port 34a (hereinafter referred to as “second paper discharge port”). Guide the sheet to the processing unit 49.

A route switching means 44 is arranged in the branch portion 32a, and guides the sheet sent from the carry-in inlet 31 to the paper discharge port (first paper discharge port) 33a of the straight path 33, or discharges the paper of the branch path 34. Guide to the mouth (second paper ejection port) 34a. Therefore, the path switching means 44 is composed of a movable guide member (flapper member) and a shift means (actuating solenoid, motor, etc .; not shown) that deflects the angular posture of the member.

A transport means for transporting a sheet is arranged in the straight path 33 and the branch path 34. In the embodiment shown in FIG. 3, a carry-in roller 45 and a paper discharge roller 46 (first paper discharge roller) are arranged in the straight-ahead path 33 in the paper discharge direction, the roller 45 is at the carry-in inlet 31, and the roller 46 is at the paper discharge port. It is arranged at 33a, and a transport roller (intermediate roller) 43 is arranged between the two rollers. Further, the branch path 34 has a paper ejection roller 47 (second paper ejection roller) arranged at the branch path port (branch portion) 32a and a third paper ejection roller (third paper ejection roller) on the downstream side thereof. Have been placed.

The rollers 45, 46, 47, and 48 (carry-in roller and first, second, and third paper discharge rollers) are configured so that the transfer force for transferring the sheet in the transfer direction is transmitted from a drive motor (not shown). There is. A conveying force for transferring the sheet in the paper ejection direction is transmitted to the carry-in roller 45 and the intermediate roller 43 from the drive motor, and a conveying force for carrying out the sheet in the first paper ejection port direction to the first paper ejection roller 46 ( Forward rotation) and transfer force (reverse rotation) that conveys the sheet in the branch path direction are transmitted from the drive motor.

A conveying force for conveying the sheet is transmitted from the drive motor to the second paper ejection roller 47 in both forward and reverse directions. Further, a conveying force for carrying out the sheet from the second paper ejection port 34a is transmitted to the third paper ejection roller 48. The illustrated device is connected from a single drive motor to the carry-in roller 45 and the first, second, and second paper discharge rollers 46, 47, 48 via a clutch mechanism so that the conveying force is transmitted.

Then, between the first paper ejection port 33a and the first post-processing unit 35, a switchback is performed in which the sheet carried out by the first paper ejection roller 46 is moved backward to a predetermined post-processing position by reversing the transport direction. A path 60 (hereinafter referred to as a “first switchback path”) is formed. Similarly, in the branch path 34, when the rear end of the sheet passes through the branch portion 32a, the transport direction is reversed and the switchback path 61 is guided to the second paper ejection port 34a (hereinafter referred to as “second switchback path”). ) Is formed. These switchback paths 60 and 61 are configured by forward / reverse control of a path for guiding the sheet (straight path 33 and a branch path 34) and a transfer roller (the first and second paper ejection rollers 46 and 47 described above).

Therefore, the sheet carried in from the carry-in entrance 31 enters the first post-processing unit 35 (processing tray 36 described later) from the straight path 33 from the rear end of the sheet opposite to the carry-in direction, and also enters the second rear from the branch path 34. The processing unit (accumulation guide 49a described later) is entered from the rear end of the sheet opposite to the loading direction. The first switchback path 60 is arranged on the downstream side and the second switchback path 61 is arranged on the upstream side at a distance in the paper ejection direction of the straight path 33 (see FIG. 2).

Sheet sensors Se1 and Se2 for detecting a sheet passing through the carry-in inlet 31 and the first paper ejection port 33a are arranged in the straight path 33. The detection signals of these sensors Se1 and Se2 are used as reference signals for sheet transfer control, for example, control of the guide direction of the route switching means 44, control of starting and stopping of the transfer roller, and sheet jam discrimination control.

In the illustrated device, the first paper ejection roller 46 and the second paper ejection roller 47 facing each other across the branch portion 32a are in a pressurized state in which the sheet is pressurized at a predetermined pressure and a pressurized state in which the pressure is reduced or separated from each other. It is composed of a pair of rollers separated from each other. Although the configuration is not shown, a pair of rollers that are in pressure contact with each other support one of them so as to be movable in the pressure contact direction. Then, the urging spring pressurizes in the direction of pressure contact with each other, and the pressing force is released or reduced by the release lever connected to the actuator such as the operating solenoid. By shifting the pressing force of the roller pair to the pressurized state and the pressurizing reduction state in this way, the pressing force is applied when the sheet is moved by the roller pair, and the pressing force is reduced when the sheet is transferred by the adjacent roller pair. Do not interfere with its transportation.

Then, the roller is shifted between the pressurized state and the pressurized release state by an actuator such as the release lever 67 and the electromagnetic solenoid 48. In this configuration, when a plurality of sheets are transferred in a predetermined direction in an overlapping state, the roller pairs are rotated in a pressure-welded state, and when the sheets are transferred by adjacent rollers, they are separated from the sheets (or pressure contact force is reduced). This is because it does not interfere with the transportation.

[1st post-processing unit]
The first post-processing unit 35 arranged on the downstream side of the first paper ejection port 33a will be described with reference to FIG. A processing tray 36 having a paper mounting surface 36a on which a sheet is placed is arranged on the downstream side of the first paper ejection port 33a so as to form a step. In the processing tray 36, a transport rotating body 62 (paddle rotating body, belt rotating body, etc.) for transferring the sheet toward a predetermined post-processing position is arranged above the tray.

Further, on the paper mounting surface 36a, a sheet edge regulating means 38 for locking the sheet at a predetermined position (post-processing position) and a matching means 39 for positioning the widthwise posture of the sheet loaded on the paper mounting surface at a reference position. , A post-processing means (staple unit) 37 for binding the sheets is arranged.

As shown in FIG. 3, the processing tray 36 includes a sheet carrying means 42 for guiding the sheet from the first paper ejection port 33a to the paper mounting surface 36a, and a post-processed sheet (bundle) on the downstream side of the paper loading surface. 1 A sheet carrying-out means 40 for carrying out to the storage stacker 41 is arranged.

The sheet carrying-in means 42 is arranged between the first paper ejection port 33a and the processing tray 36, and the sheet carried out from the paper ejection port is inverted (switchback pass) in the conveying direction and placed on the paper loading surface 36a. Send to. The seat loading means 42 includes an elevating roller, a paddle rotating body, a belt rotating body, and the like. The one shown in the figure is composed of an elevating roller that can be raised and lowered between the operating position that engages with the sheet carried out from the first paper ejection port 33a and the standby position retracted from the operating position, and the rear end of the sheet is the first paper ejection port. It rotates in the forward direction until it is carried out from 33a, and then is connected to an elevating motor and a forward / reverse motor (not shown) so as to reverse in the opposite direction.

The sheet unloading means 40 is composed of a conveyor mechanism that reciprocates between the processing position and the storage stacker 41 on the downstream side along the paper loading surface 36a. The conveyor mechanism is composed of an engaging member 40a that engages with the edge of the sheet bundle on the paper mounting surface, and a belt (not shown) that reciprocates the engaging member along the paper mounting surface. Further, on the paper loading surface 36a, a roller (fixed roller) 63 facing the above-mentioned sheet carrying means 42 (elevating roller; the same applies hereinafter) is arranged, and a sheet bundle is nipated between the sheet loading means 42 (elevating roller; the same applies hereinafter) to the elevating roller 42 to discharge the paper. Transfer to.

[Second post-processing unit]
The second post-processing unit 49 arranged on the downstream side of the second paper ejection port 34a will be described with reference to FIG. The second post-processing unit 49 is loaded with sheets sent from the branch path 34 and integrated, and the integrated guide 49a, the binding processing means 52 for binding the accumulated sheet bundles, and the sheet bundles are bound from the central portion. Folding processing means 53 and 54 for folding are arranged.

The accumulation guide 49a is composed of a guide member having a loading surface 49b for supporting and loading the sheet sent from the second paper ejection port 34a in a vertically standing state (standing posture). The tip regulating means 50 that locks the end (tip) of the sheet and regulates the position is movably arranged on the stacking guide 49a along the loading surface. Further, the integration guide 49a is provided with a matching means 51 for positioning the width direction of the loaded sheet at a reference position.

The binding processing means 52 is composed of a saddle stitch staple unit that binds the central portion of the sheet bundle accumulated on the loading surface 49b. Since the configuration of this staple unit is widely known, the description thereof will be omitted. The folding processing means is composed of a folding roll 53 and a folding blade 54. The folding roll 53 is a pair of pressure-welded rolls, which are connected to a drive motor (not shown) that rotates in the clockwise direction (direction in which the folded sheet is ejected) in FIG.

The folding blade 54 is composed of a plate-shaped member for inserting the fold position of the sheet bundle between the rolls, and is a shift motor (non-reciprocating) so as to reciprocate between a standby position separated from the roll pair and an operating position between the rolls. It is connected to (shown). The matching means 51 is composed of a pair of left and right matching plates that can move a sheet supported on the loading surface in the width direction, and includes a matching motor (not shown).

A paper ejection path 65 and a paper ejection roller 66 (fourth paper ejection roller) for carrying out the folded sheet bundle are arranged on the downstream side of the folding roller 53, and a second storage stacker 55 is arranged on the downstream side thereof. There is. The paper ejection path 65 is arranged in a direction substantially orthogonal to the loading surface 49b of the second post-processing unit 49, and carries out the sheet in the same direction as the straight path 33. The second storage stacker 55 is arranged below the first storage stacker 41.

"Buffer part"
The sheet sent to the carry-in port 31 in the above configuration is guided from the first paper ejection port 33a to the first post-processing unit 35 via the straight path 33, or is guided from the branch path 34 to the second post-processing unit 49. Will be done. Then, the sheet bundles accumulated for each copy (for each printing group) in the first post-processing section 35 are bound and then stored in the first storage stacker 41 (first post-processing mode). In addition, the sheet bundles accumulated in the second post-processing unit 49 for each unit are stored in the second storage stacker 55 after being subjected to the binding process and the folding process (second post-processing mode).

Therefore, during the post-processing operation of the first post-processing unit 35 or the second post-processing unit 49, the sheet sent to the carry-in inlet 31 is retained in the middle of the route until the post-processing operation of the downstream post-processing unit is completed. It is necessary to control the transfer of the sheets to be made to stand by. This is because the printing process of forming an image on the sheet by the image forming apparatus A on the upstream side proceeds without interruption (during the post-processing operation).

Therefore, a route buffer unit Pb (hereinafter referred to as a buffer unit) is provided in the transport path (straight path 33 and branch path 34) to temporarily stock sheets sent from the upstream during the post-processing operation. The number of sheets to be retained in this path may be one or a plurality depending on the length of the post-processing time. When the process speed in the image forming apparatus A on the upstream side becomes high, the number of sheets retained in the buffer portion Pb of the post-processing apparatus B becomes large.

As shown in FIG. 3, the illustrated device arranges the buffer portion Pb in the straight path 33 and the branch path 34 located on the downstream side of the branch portion 32a. In the figure, a buffer portion Pb is shown between the first paper discharge roller 46 (first transport roller; the same applies hereinafter) of the straight path 33 and the second paper discharge roller 47 (second transport roller; the same applies hereinafter) of the branch path 34. Is arranged, and the seat is supported in a state of straddling both rollers (bridge support structure). That is, the distance between the first paper ejection roller 46 and the second paper ejection roller 47 is arranged at a distance shorter than the length in the transport direction of the minimum size sheet to be post-processed.

Further, the first and second paper ejection rollers 46 and 47 are connected to a drive motor (not shown) so as to be capable of forward and reverse rotation. Then, the control means 76, which will be described later, reverses the first paper ejection roller 46 from the forward rotation to the reverse rotation, guides the sheet sent to the straight path 33 to the branch path 47, and sends it to the buffer unit Pb. The sheets retained in the buffer section Pb by rotating the first and second paper ejection rollers 46 and 47 clockwise (forward rotation) at the subsequent paper feeding timing are guided to the first post-processing section 35, and the first , The sheets are transferred to the second post-processing unit 49 by rotating the second paper ejection rollers 46 and 47 counterclockwise (counterclockwise).

In the present invention, the first and second transport rollers for temporarily retaining the sheet are "roller pairs 46 arranged at the paper ejection port (first paper ejection port) of the straight path 33" and "branch". The case where the roller pair 47 ”is arranged at the path entrance of the path 34 is shown. If this is a pair of front and rear rollers that engage with the sheet with a span (interval) shorter than the length in the transport direction of the sheet, the position is not limited to the paper ejection port and the route entrance, and may be any location in the middle of the route. .. Further, the first and second conveying rollers are preferably a pair of rollers capable of forward and reverse rotation, but the sheet may be composed of a plurality of pairs of rollers capable of transferring the sheet in the direction opposite to the paper ejection direction.

The control of each of the transport rollers (paper ejection rollers) when the sheet is retained in the buffer portion Pb will be described. The sheet sent to the carry-in inlet 31 is rotated by the carry-in roller 45 and the first paper discharge roller 46 (first transport roller) in the paper discharge direction (forward rotation direction; clockwise in FIG. 3; the same applies hereinafter), and the rear end of the sheet is At the stage of passing through the branch portion 32a, the first paper ejection roller 46 is rotated in the opposite direction of paper ejection (counterclockwise rotation in FIG. 3; the same applies hereinafter). At the same time, the path switching means 44 is deflected to the posture of guiding the sheet toward the second paper ejection port side (broken line state in FIG. 3), and the second paper ejection roller 47 (second transport roller) is rotated counterclockwise in FIG. The seat is guided to the branch path 34 from the rear end side.

The control of the path switching means 44 and the transport rollers (paper ejection rollers) 46 and 47 controls the drive mechanism based on the detection signals from the sheet sensors Se1 and Se2. The control means 75, which will be described later, rotates the first paper ejection roller 46 and the second paper ejection roller 47 by a preset amount of rotation according to the sheet size, and stops both rollers. Then, the sheet sent from the carry-in inlet 31 is sent to the buffer portion Pd of the branch path 34, and temporarily stops at this position.

[Control configuration]
The control configuration in the image forming system of FIG. 1 will be described. FIG. 12 is a block diagram of the control configuration, which is composed of an image formation control unit 70 and a post-processing control unit 75. The image formation control unit 70 includes a paper feed control unit 72 and a mode setting means 71. Further, the mode setting means 71 includes an input unit 73 such as a control panel. The image formation control unit 70 forms an image on the sheet under the image formation conditions set by the mode setting means 71. The paper feed control unit 72 controls the paper feed operation of feeding the sheet of the size set by the mode setting means 71 from the paper feed unit 11 to the image forming unit 13. The mode setting means 71 sets image formation conditions such as color / monochrome setting, reduction magnification setting, and cover print setting. At the same time, the mode setting means 71 sets a post-processing mode for post-processing the image-formed sheet.

The illustrated post-processing device B is configured to be configurable to a first post-processing mode (end binding processing mode), a second post-processing mode (bookbinding binding processing mode), and a third post-processing mode (printout mode). ing. In the first post-processing mode, the image-formed sheets are aligned and accumulated in the processing tray 36 (first accumulating portion), bound, and stored in the first accommodating stacker 41. In the second post-processing mode, the image-formed sheets are aligned and accumulated on the integration guide 49a (second integration unit), saddle-stitched, folded, and stored in the second storage stacker 55. In the third post-processing mode, the sheet sent to the carry-in entrance 31 is stored in the first storage stacker 41 without post-processing. Here, the "saddle stitching process" is a finishing process for binding one or more locations along the end face of the sheet bundle that has been aligned and accumulated, and the "saddle stitching process" is a finishing process for binding the sheet bundle that has been aligned and accumulated. It means a finishing process in which a plurality of places in the central portion (seat center) are stitched together.

The post-processing control unit 75 includes a control CPU 76 that operates the post-processing device B according to a designated post-processing mode (finishing process), a ROM 77 that stores an operation program, and a RAM 78 that stores control data. The control CPU 76 includes a transport control unit 76a that controls the transport of the sheets sent to the carry-in inlet 31, an integration operation control unit 76b that controls the stacking operation of the sheets, and a binding operation control that controls the binding process of the sheet bundle. A folding operation control unit 76d for controlling a bundle folding operation of sheets is provided.

Each of the control units 76a to 76d has an operation mode in which the first post-processing unit 35 post-processes the sheet (first post-processing mode) and an operation mode in which the second post-processing unit 49 post-processes the sheet (second post-processing). Mode) is selected to operate either mode.

The transfer control unit 76a is connected to a control circuit (driver) of a carry-in roller 45, (intermediate roller 43), and a drive motor (not shown) of the first paper discharge roller 46 of the transfer path 32, and the transfer path 32. The detection signal is received from the seat sensors Se1 and Se2 arranged in. Further, the transport control unit 76a is connected to a control circuit (driver) of the drive motors (not shown) of the second and third paper ejection rollers 47 and 48 described above, and receives a detection signal from the sheet sensor Se3 of the branch path 34. ..

Further, the transfer control unit 76a retains the sheet sent to the carry-in port 31 in the buffer unit Pb during the processing operations (for example, post-processing operation, folding processing operation, etc.) of the first and second post-processing units 35 and 49. Take control. Therefore, the transfer control unit 76a includes a buffer sheet number calculation means 79 for calculating the number of sheets to be retained during the post-processing operation, and a buffer sheet transfer amount setting means 80 for transferring the buffer sheet at the carry-in inlet 31 to the buffer unit Pb. It is inherent. Details of the buffer sheet number calculation means 79 and the buffer sheet transfer amount setting means 80 will be described later.

The drive motor of the straight path 33 and the drive motor of the branch path 34 may be composed of a single motor or individual motors. When composed of a single motor, the drive is transmitted to each transfer roller via the clutch means. The integrated operation control unit 76b sends a control signal to the drive circuits of the forward / reverse motor of the sheet loading means 42 (elevating roller) and the paper ejection motor of the sheet unloading means 40 in order to integrate the sheets in the first integrated unit 35. Send. Further, the binding operation control unit 76c transmits a control signal to the drive circuit of the drive motor (not shown) built in the saddle stitch staple device 37 of the first integrated unit 35 and the saddle stitch staple device 52 of the second integrated unit 49. To do.

The folding operation control unit 76d is connected to a drive circuit of a roll drive motor that drives and rotates the folding roll pair 53, and this control unit is connected to the second and third paper ejection rollers 47 and 48 of the branch path 34 and the integration guide. A control signal is transmitted to the control circuit of the shift means that moves and controls the tip regulating means 50 of 49a to a predetermined position, and a detection signal is received from a seat sensor (not shown) arranged in these paths.

[Buffer sheet number calculation means]
Next, the buffer sheet number calculation means 79 will be described. The calculation means 79 is inherent in the transport control unit 76a. The calculation means 79 includes the length (size information) of the sheet sent from the image forming apparatus A in the transport direction and the post-processing time (for example, sheet matching time + binding processing time + folding processing time) set in advance and stored in the RAM 78. The number of sheets to be retained in the route is calculated from (+ processing sheet unloading time). This is calculated by [Bs = Td / Tp] ... (Equation 1) when the post-processing time is Td, the image formation process time is Tp, and the number of buffer sheets is Bs. As a result, the number of sheets to be retained in the buffer unit Pb during the post-processing operation of the first and second post-processing units 35 and 49 is set.

[Buffer sheet transport amount setting means]
When the buffer sheet calculated by the buffer sheet number calculation means 79 is transferred to the buffer unit Pb and temporarily stopped (retained), the transfer control unit 76a offsets the buffer sheet back and forth in the path direction and superimposes it. Stop it. This is because the buffer sheet is quickly (speedily) and reliably (without jamming) transferred to the first and second post-processing units 35 and 49 after the post-processing operation is completed.

The device shown in the figure conveys the first buffer sheet n to the buffer unit Pb, offsets the second buffer sheet upstream by a preset offset amount δ, and stops (shifts the position). .. Therefore, for example, the transport control unit 76a sets the transport amount of the first and second paper discharge rollers 46 and 47 according to the number of buffer sheets (to different transport amounts) based on the signal obtained by detecting the sheet tip with the paper discharge sensor Se2. Set.

For example, when the transport amount of the first buffer sheet is set to (Ln), the transport amount of the second buffer sheet is set to (Ln-δ), and the transport amount of the third buffer sheet is set to (Ln-2). Set to × δ), and then gradually shorten the transport amount in the same manner. The reason why the plurality of sheets are displaced (offset) in the transport direction and retained in this way will be described later.

[Explanation of post-processing operation]
The post-processing control unit 75 configured as described above causes the post-processing device B to execute the next processing operation. As described above, the post-processing control unit 75 has a first post-processing mode (edge binding process in the first post-processing unit 35), a second post-processing mode (bookbinding process in the second post-processing unit 49), and a third post-processing mode. (Print sheet storage processing in the first post-processing unit 35) is provided. Then, the sheets sent from the image forming apparatus A according to the mode set by the mode setting means 71 are accumulated in the first post-processing unit 35 or the second post-processing unit 49 for post-processing, and then on the downstream side. It is stored in the stackers 41 and 55. Hereinafter, [Explanation of sheet transfer order to the post-processing unit] [Explanation of buffer sheet transfer operation] [First post-processing mode operation] [Second post-processing mode operation] will be described in this order.

[Explanation of sheet transfer order to the post-processing unit]
As shown in FIG. 5, the sheet at the carry-in inlet 31 is transferred to the first post-processing unit 35 by the first switchback path 60 and to the second post-processing unit 49 by the second switchback path 61. The sheets are sent to the carry-in port 31 in the order of image formation (n) (n + 1) (n + 2). The control means (control CPU) 76 transfers this sheet from the straight path 33 to the first post-processing unit 35 and from the branch path 34 to the second post-processing unit 49. Then, the first and second post-processing units 35 and 49 temporarily retain the sheet in the buffer unit Pb during the post-processing operation time.

In the first post-processing unit 35, the sheets sent to the carry-in port 31 are stacked and accumulated on the paper mounting surface 36a of the processing tray 36 in that order (n, n + 1, n + 2). The buffer unit Pb is also stacked in the same order (n, n + 1, n + 2) and retained in the path. Further, the second post-processing unit 49 is also stacked and accumulated in the same order (n, n + 1, n + 2). At this time, the first post-processing unit 35 and the buffer unit Pb have the same vertical posture of the sheets, but the second post-processing unit 49 are integrated so that the vertical postures of the sheets are different.

[Explanation of transfer of buffer sheet to post-processing section]
When the plurality of sheets retained in the buffer unit Pb are transferred to the first post-processing unit 35, they are simultaneously transferred in a bundled state, and when they are transferred to the second post-processing unit 49, the sheets are carried in. Transfer one by one in the order sent to 31. The state will be described with reference to FIG. The sheets are sent to the carry-in port 31 in the order of image formation (n) (n + 1) (n + 2). This sheet is stacked on the buffer unit Pb in the same order, (n) (n + 1) (n + 2).

Then, the control means 76 rotates the first and second paper ejection (conveying) rollers 46 and 47 located in the buffer unit Pb at the stage when the post-processing operation of the post-processing unit 35 (49) is completed in the direction of conveying the sheet. Control. At this time, the control means 76 simultaneously transfers the buffer sheets stacked in a bundle to the first processing unit 35 in a bundled state, and transfers the buffer sheets stacked in a bundle to the second post-processing unit 49. Transfer one by one.

[First post-processing mode]
The operation procedure of the first post-processing mode (end binding processing mode) will be described with reference to FIG. When the power of the device is turned on, the control means 76 executes the initialization operation (St01). Although the description of the initialization operation is omitted, the route switching means 44 guides the sheet along the straight path 33 in the paper ejection direction. The front edge and the rear edge of the sheet are detected by the sensor Se1 and the sensor Se2, and the timer is started based on the detection signal (St02). Which of the detection signals of both sensors Se1 and Se2 is used as a reference to determine (monitor) the sheet transport state is appropriately set.

At the timing when the tip of the sheet is carried out from the first paper ejection port 33a, the elevating roller 42 (sheet carrying means) is lowered from the standby position to the operating position where the sheet is engaged. At the same time, the elevating roller 42 is rotated in the paper ejection direction to transfer the sheet in the paper ejection direction (St03). The elevating roller 42 is reversed in the opposite direction of paper ejection at the timing when the rear end of the sheet is ejected from the first paper ejection port 33a (St04). Then, the sheet is carried into the processing tray 36 arranged on the downstream side of the first paper ejection port 33a by reversing the transport direction (switchback) from the rear end side, and is abutted against the sheet edge regulating means 38 on the tray. It is stopped (St05). Then, the control means 76 positions the sheet carried into the first post-processing unit 35 at the reference position in the width direction.

The control means 76 repeats the above-mentioned operations of steps St02 to St05 until the job end signal is received from the image forming apparatus A. As a result, the sheets image-formed by the image forming apparatus A are aligned and accumulated in the first post-processing unit 35. Then, upon receiving the job end signal from the image forming apparatus A, the control means 76 causes the post-processing means 37 (stapler unit) of the first post-processing unit 35 to execute the post-processing operation (St06). Next, when the control means 76 receives the operation end signal from the post-processing means 37, the control means 76 carries out the processed sheet bundle toward the first storage stacker 41 on the downstream side (St07).

At the same time as the execution of the post-processing operation, the control means 76 receives post-processing mode setting information (in this case, the first post-processing mode), image formation processing speed (process speed), and sheet size information from the image forming apparatus A. Is obtained, and the post-processing operation time data in the first post-processing unit 35 stored in the RAM 78 of the post-processing device B is called. Then, based on this information, the buffer sheet number calculation means 79 calculates the number of sheets to be retained in the route, and the buffer sheet transfer amount is calculated by the transfer amount setting means 80 (St08).

When the succeeding sheet reaches the carry-in inlet 31, the control means 76 detects this with the carry-in sensor Se1 and obtains the estimated time for the rear end of the sheet to reach the branch portion 32a from the timer time of the RAM 78. Then, the timer is activated by the detection signal of the carry-in sensor Se1.

Next, when the estimated time when the rear end of the sheet passes through the branch portion 32a elapses (timer up), the control means 76 changes the route switching means 44 in the direction of the broken line in FIG. 3, and at the same time, the first paper ejection roller 46 and the second paper ejection roller 46. The paper ejection roller 47 is rotated in the direction opposite to the paper ejection (St09). Then, the sheet enters the branch path 34 from the rear end side, and the control means 76 rotates the first and second paper ejection rollers 46 and 47 by the amount set by the transport amount setting means 80 and stops (St10).

When the next subsequent sheet (n + 1) reaches the carry-in port 31, the control means 76 similarly carries this sheet into the buffer unit Pb. The transport amount of this sheet is set to be smaller by the offset amount δ than the transport amount of the previous sheet (n). Further, the next sheet (n + 2) is also carried into the buffer unit Pb in the same manner, and the transfer amount is reduced by the offset amount δ from the previous sheet (n + 1) (St11).

In this way, the sheet sent from the image forming apparatus A during the execution of the post-processing operation by the first post-processing unit 35 is in a state of straddling the straight path 33 and the branch path 34 with the branch portion 32a in between (bridge state). ) Temporarily held (execution of St11 above). Therefore, the control means 76 receives a sheet import permission signal from the first post-processing unit 35 (St12). With this signal as a reference, the first and second paper ejection rollers 46 and 47 are rotated in the paper ejection direction (clockwise in FIG. 3). Then, the buffer sheets are transferred from the buffer unit Pb toward the first paper ejection port 33a in a state where a plurality of the buffer sheets are overlapped (St13). The control means 76 rotates the elevating roller 42 and the transport rotating body 62 to abut the sheet bundle against the sheet edge regulating means 38 of the first post-processing unit 35 of the post-processing device B to stop the sheet bundle.

[Second post-processing mode]
Next, the second post-processing mode (bookbinding binding processing mode) will be described with reference to FIG. When the power of the device is turned on, the initialization operation of the device is executed (St01), and when the sheet is sent to the carry-in inlet 31, the tip thereof is detected and the timer is started (St02). At the estimated time (timer up) when the rear end of the sheet passes through the branch portion 32a, the path switching means 44 is deflected, and the first and second paper ejection rollers 46 and 47 are rotated in the opposite directions of the paper ejection to advance the sheet in a straight path. Guide from 33 to the branch route 34. This sheet is sent from the second paper ejection port 34a to the second post-processing unit 49 and is accumulated in the accumulation guide 49a (St20). When the control means 76 receives the job end signal from the image forming apparatus A, the control means 76 moves the sheets accumulated in the integration guide 49a to the binding processing position and performs the binding processing by the binding means (St21).

Next, the control means 76 moves the sheet bundle to the folding processing position, rotates the folding roll pair 53 in the folding processing direction, and at the same time moves the folding blade 54 from the standby position to the operating position. Then, the sheet bundle is folded from the central portion and the folding process is performed (St22). After the folding operation is executed, the sheet bundle is sent to the second storage stacker 55 and stored (St23).

At the same time as the execution of the post-processing operation, the control means 76 calculates the number of sheets to be retained by the buffer sheet number calculation means 79 and the transport amount of each buffer sheet by the transport amount setting means 80, as in the first post-processing mode. St24).

Then, when the succeeding sheet reaches the carry-in inlet 31, the control means 76 conveys the succeeding sheet to the buffer unit Pb and retains it in the same manner as in the first post-processing mode (St25). Similar to the first post-processing mode, this buffer sheet retention is also retained in a state (superimposed) in which a plurality of sheets are overlapped by reducing the transport amount by the offset amount δ.

In this way, the sheet sent from the image forming apparatus A during the execution of the post-processing operation (binding processing operation and folding processing operation) in the second post-processing unit 49 includes the straight path 33 and the branch path 34 with the branch portion 32a interposed therebetween. It is temporarily held in a state of straddling (bridge state) between. Therefore, the control means 76 receives a sheet carry-in permission signal from the second post-processing unit 49 (St26). The third paper ejection roller 48 is rotated in the paper ejection direction (counterclockwise in FIG. 3) with reference to this signal. Then, the buffer sheet n initially retained is carried into the accumulation guide 49a from the second paper ejection port 34a.

At this time, the stopper 56 is locked at that position so that the overlapping subsequent buffer sheets (n + 1, n + 2) are not pulled in. Then, the control means 76 transfers the plurality of sheets retained in the buffer unit Pb to the accumulation guide 49a in the order of being sequentially retained. The sheet transport speed at this time (peripheral speed of the third paper ejection roller 48) is set to be higher than the process speed of the image forming apparatus A. The operation of transferring the buffer sheet to the second post-processing unit 49 will be described later.

In this way, the sheet sent from the image forming apparatus A during the execution of the post-processing operation by the second post-processing unit 49 is a buffer unit arranged between the straight path 33 and the branch path 34 with the branch portion 32a in between. It is sent to Pb and temporarily held in a state of being bridged by the first paper ejection roller 46 and the second paper ejection roller 47 at predetermined intervals. (Execution of St25 above). Then, when the second post-processing unit 49 becomes able to carry in the sheets, the control means 76 sends the buffer sheets (n to n + 2) one by one from the second paper ejection port 34a in the feed order (the order in which the buffer sheets are sent to the carry-in inlet 31). Transfer to the integration guide 49a. Then, after all the buffer sheets are carried on the accumulation guide, the subsequent sheets are accumulated on the accumulation guide.

The sheet sent from the image forming apparatus A to the carry-in inlet 31 during the operation of transferring the buffer sheet to the integration guide 49a is retained in the buffer unit Pb. Then, the transfer is repeated until all the sheets are transferred from the buffer unit Pb to the second post-processing unit 49. For this purpose, the speed Vb (peripheral speed of the third paper ejection roller 48 in the illustrated embodiment) for transferring the buffer sheet to the second post-processing unit 49 is set to the speed Va (process speed) for forming an image by the image forming apparatus A. ) Needs to be set to a higher speed (Vb> Va). Then, when this speed difference reaches the conveyed amount of the retained sheets, all the retained sheets are transferred to the accumulator 49 on the downstream side.

[Explanation of operating status of buffer sheet transfer]
"First post-processing mode"
The state of transporting the buffer sheet in the first post-processing mode will be described with reference to FIG. 7. FIG. 3A shows a state in which a plurality of sheets are conveyed to the buffer unit Pb and temporarily retained. The sheets sent from the carry-in port 31 to the buffer unit Pb are stacked on the first sheet (n) in the order of the second sheet (n + 1) and then on the third sheet (n + 3) to form the first paper ejection roller 46. It is held by the second paper ejection roller 47. The plurality of sheets are stacked in a scale shape with an offset amount of δ in the feed order (the order in which they are sent to the carry-in inlet 31).

When the control means 76 carries the buffer sheet into the first post-processing unit 35, the first paper ejection roller 46 and the second paper ejection roller 47, which are stopped, are discharged from the sheet as shown in FIG. 7A. It rotates in the direction of guiding through the mouth 33a (clockwise in the figure). Then, the plurality of stacked sheets are sent from the first paper ejection port 33a to the first accumulating portion (processing tray) 35, and by the forward / reverse rotation of the elevating roller 42, the sheet edge regulating means 38 is brought into the state of FIG. 7B. Be struck.

At this time, a conveying force is applied to the plurality of sheets from the conveying rotating body 62. As shown in FIG. 8 (b), the transport force (f1, f2, f3) has the largest transport force f3 acting on the uppermost overlapping sheet (n + 2) that engages with the transport rotating body 62, and sequentially the same. The transport force of the lower sheet (n + 1) decreases in the order of f2 and f1. At this time, each sheet is displaced by an offset amount of δ so as to approach the sheet edge regulating means 38.

Therefore, in the sheets that are stacked by shifting the positions by a predetermined amount in the feed order, the sheet located at the bottom layer of the stack is closest to the stopper (sheet edge regulating means 38), and the sheet located at the top layer of the stack is the farthest from the stopper. The position is shifted so that it becomes. On the contrary, the maximum transport force f is applied to the sheet located at the uppermost layer.

"Second post-processing mode"
The state of transporting the buffer sheet in the second post-processing mode will be described with reference to FIGS. 9 to 11. FIG. 3A shows a state in which a plurality of sheets are conveyed to the buffer unit Pb and temporarily retained. The sheets sent from the carry-in port 31 to the buffer unit Pb are stacked on the first sheet (n) in the order of the second sheet (n + 1) and then on the third sheet (n + 3) to form the first paper ejection roller 46. It is held by the second paper ejection roller 47. The plurality of sheets are stacked in a scale shape with an offset amount of δ in the feed order (the order in which they are sent to the carry-in port). The offset amount δ is set at the same or different intervals as the offset amount in the first post-processing mode.

When the control means 76 can carry the sheets into the second post-processing unit 49 (when the post-processing operation in the second post-processing unit is completed), the sheets retained in the buffer unit Pb are sent one by one in the order of feeding. It is carried into the accumulation guide 49a from the second paper ejection port 33a. Therefore, the control means 76 rotates the second paper ejection roller 47 and the third paper ejection roller 48 in the sheet transport direction. At this time, the first paper ejection roller 46 rotates in the same direction or is separated from the sheet.

Next, the control means 76 shifts the first paper ejection roller 46 and the second paper ejection roller 47 to a state (standby posture) separated from the sheet. Then, as shown in FIG. 10, the sheet is nipped into the third paper ejection roller 48, and is fed to the integration guide 49a by its rotation. At this time, the locking stopper 56 is operated so that the overlapping upper layer sheets (n + 1, n + 2) are not carried away.

The plurality of sheets retained in the buffer portion Pb in this way are sent to the integration guide 49a in the order of the lowermost layer sheet (n; the sheet retained first) to the upper layer sheet (n + 1, n + 2).

The transport mechanism of the branch path 34 shown in FIG. 6B will be described. As described above, the second paper ejection roller 47 and the third paper ejection roller 48 are arranged at intervals in the branch path 34, and the sheet is transferred from the second paper ejection port 34a to the second post-processing unit (accumulation guide 49a). It is configured to send. A separating means for preventing double feeding of sheets is arranged between the third paper ejection roller 48 and the second paper ejection roller 47, and one sheet (the lowest layer sheet) of the overlapping sheets is carried out. Prevents you from being taken away.

FIG. 11 shows a state in which the succeeding sheet is sent from the image forming apparatus A to the carry-in inlet 31 during the operation of transporting the sheets (n, n + 1, n + 2 ...) Retained in the buffer unit Pb to the second post-processing unit 49. Is shown. In this state, in the first paper ejection roller 46, the rear end portion of the buffer sheet is sent in the direction of arrow A in the figure, the succeeding sheet sent from the carry-in inlet 31 is sent in the direction of arrow B, and both sheets overlap in opposite directions. Move in the direction of passing each other.

Therefore, the control means 76 rotates the third paper ejection roller 48 in the direction of the arrow in the figure. (The second paper ejection roller 47 either rotates in the same direction or is stopped and separated.) Then, the sheet retained in the buffer portion Pb is moved from the second paper ejection port 34a to the second post-processing unit 49. Will be sent to. At this time, the control means 76 separates the first paper ejection roller 46 (roller pair). As a result, the progress of the succeeding sheet fed to the first paper ejection roller 46 in the opposite direction is not hindered.

Although the structure is not shown, one of the roller pairs is axially supported so as to be movable in the pressure contact direction and the separation direction, and is urged by an urging spring in the pressure contact direction. Then, a release lever is provided to move (shift) the position of the movable roller in a direction away from the spring, and the release lever is moved by a driving means such as an operating solenoid or an operating cam.

The separating means shown in FIG. 6B is composed of a braking lever 56 having a locking portion and an operating solenoid 57 that swings the braking lever between the standby position and the operating position. Then, when the lower layer sheet (for example, the first buffer sheet) is transferred from the second output port 34a to the accumulation guide 49a, the upper layer sheet (second buffer sheet) is locked to prevent the lower layer sheet (for example, the first buffer sheet) from being carried away. There is.

A Image forming device B Post-processing device 31 Carry-in port 32 Transport path 32a Branch part 33 Straight path 33a First paper ejection port 34 Branch path 34a Second paper ejection port 35 First post-processing section (first integrated section)
36 Processing tray 37 Post-processing means (stapler unit)
41 First storage stacker 42 Lifting roller (seat loading means)
43 Transport roller (intermediate roller)
44 Route switching means 45 Conveying rollers (pair of carry-in rollers)
46 First paper ejection roller (pair of first paper ejection roller)
47 Second paper ejection roller (pair of second paper ejection roller)
48 Third paper ejection roller (pair of third paper ejection roller)
49 Second post-processing section (second integration section)
49a Stacking guide 52 Saddle stitching means 56 Braking lever 66 Paper ejection roller (4th paper ejection roller)
70 Image formation control unit 75 Post-processing control unit 76 Control means 79 Buffer sheet number calculation means 80 Transport amount setting means Pb buffer unit

Claims (4)

The carry-in entrance that accepts the seat and
The sheet received from the carry-in port is branched from the path through a path and a branch portion for guiding the sheet to the first paper ejection port, and heads for a second paper ejection port different from the first paper ejection port. A transport route provided with a branch route for guiding the sheet received from the carry-in entrance, and a transport route.
A first paper ejection roller pair provided in the path between the branch portion and the first paper ejection port and ejecting a sheet from the first paper ejection port,
A second transport roller pair provided in the branch path and transports the sheet in the reverse transport direction toward the second paper ejection port, and
A third paper ejection roller pair that ejects a sheet conveyed in the reverse conveying direction by the second conveying roller pair from the second paper ejection port, and a third paper ejection roller pair.
A first accumulating portion for accumulating sheets ejected by the first paper ejection roller pair,
A second stack for accumulating sheets ejected by the third paper ejection roller pair, and
In a part of the transport path, a retention sheet in which a sheet received from the carry-in port is held by pressure contact and retained at at least one of the first paper discharge roller pair and the second transport roller pair, and then from the carry-in port. The received succeeding sheets are stacked in a bundle to form a stagnant sheet bundle, and the stagnant sheet and the succeeding sheet are discharged one by one from the stagnant sheet bundle to the second stack from the second paper ejection port. A control means for controlling the first paper ejection roller pair, the second transport roller pair, and the third paper ejection roller pair.
An aftertreatment device equipped with. The control means has the first paper ejection roller pair and the second transport roller pair so as to stack the stagnant sheets in advance of the succeeding sheets by a predetermined amount in the reversing transport direction when the stagnant sheet bundle is generated. The post-processing apparatus according to claim 1, which controls and. The first paper ejection roller pair is configured so that it can be pressure-welded and separated.
When the sheet received from the carry-in port is discharged to the first stacking section, the control means press-contacts the first paper discharge roller pair and discharges the stagnant sheet bundle to the second stacking section. The post-processing apparatus according to claim 2, wherein the first paper ejection roller pair, the second transport roller pair, and the third paper ejection roller pair are controlled so as to separate the first paper ejection roller pair. An image forming device that forms an image on a sheet,
A post-processing device that post-processes the sheet sent from the image forming device,
Consists of
The image forming system, wherein the post-processing device is the post-processing device according to any one of claims 1 to 3.

Images