JP2024053315A - SHEET PROCESSING APPARATUS, IMAGE FORMING APPARATUS, AND IMAGE FORMING SYSTEM - Google Patents

Abstract

[Problem] To provide a sheet processing device capable of improving edge alignment when multiple sheets are overlapped using a circulating transport path and then bound into a sheet bundle. [Solution] A sheet processing device equipped with a circulating transport path that transports multiple sheets while overlapping them so that they can be transported as a sheet bundle, the sheet processing device includes a circulating transport path provided midway between an inlet transport path for sheets and an outlet transport path for the sheet bundle, and a control unit that controls the transport operation of the sheets and the sheet bundle, and when the sheet bundle is transported via the outlet transport path, the control unit controls the transport operation of the multiple sheets such that, among the sheets forming the sheet bundle, the leading edge in the transport direction of a preceding sheet that has been transported first from the inlet transport path precedes the leading edge in the transport direction of a succeeding sheet that has been transported after the preceding sheet. [Selected Figure] Figure 12

Description

The present invention relates to a sheet processing device, an image forming device, and an image forming system.

Sheet processing devices are known that perform so-called post-processing, such as aligning a stack of sheet media (hereafter referred to as "sheets") to form a sheet bundle, and folding the sheets. Also known are image forming devices that have a function equivalent to the above-mentioned sheet processing devices and a function for forming images on sheets, and image forming systems in which the sheet processing device and the image forming device are housed in separate housings and operate in conjunction with each other.

In a sheet processing device, a technology has been disclosed in which the sheets are circulated and transported to overlap each other in order to perform folding processing on a sheet bundle made up of multiple overlapping sheets (see Patent Document 1).

Using the technology disclosed in Patent Document 1, it is possible to stack multiple sheets using a circulating conveying path, but it does not solve the problem of the edges of the sheets becoming misaligned when the stacked sheets are bound in the binding unit 300.

The present invention aims to provide a sheet processing device that can improve edge alignment when binding a stack of sheets after stacking multiple sheets using a circulating transport path.

In order to solve the above technical problems, one aspect of the present invention is a sheet processing device having a circulating transport path that transports multiple sheets while overlapping them so that they can be transported as a sheet bundle, the circulating transport path being provided midway between an inlet transport path for the sheets and an outlet transport path for the sheet bundle, and a control unit that controls the transport operation of the sheets and the sheet bundle, and when the sheet bundle is transported via the outlet transport path, the control unit controls the transport operation of the multiple sheets so that, among the sheets that form the sheet bundle, the leading edge in the transport direction of a preceding sheet that was previously transported from the inlet transport path precedes the leading edge in the transport direction of a succeeding sheet that was transported after the leading sheet.

According to the present invention, it is possible to improve the alignment of the edges when stacking multiple sheets using a circulating transport path and then binding the sheet bundle.

1 is a side view showing an embodiment of an image forming apparatus including a sheet processing apparatus according to the present invention. 1 is a diagram showing a schematic configuration of an embodiment of an image forming system according to the present invention. FIG. 4 is a block diagram showing an example of a control configuration according to the embodiment. FIG. 2 is a diagram showing an internal configuration of a folding processing unit as an embodiment of a sheet processing apparatus according to the present invention. 6 is an enlarged view of an internal configuration illustrating one process of a folding and conveying operation in the folding processing unit. FIG. 6 is an enlarged view of an internal configuration illustrating one process of a folding and conveying operation in the folding processing unit. FIG. 6 is an enlarged view of an internal configuration illustrating one process of a folding and conveying operation in the folding processing unit. FIG. 6 is an enlarged view of an internal configuration illustrating one process of a folding and conveying operation in the folding processing unit. FIG. 6 is an enlarged view of an internal configuration illustrating one process of a folding and conveying operation in the folding processing unit. FIG. 6 is an enlarged view of an internal configuration illustrating one process of a folding and conveying operation in the folding processing unit. FIG. 6 is an enlarged view of an internal configuration illustrating one process of a folding and conveying operation in the folding processing unit. FIG. FIG. 2 is a diagram showing an internal configuration of a binding processing unit as an embodiment of a sheet processing apparatus according to the present invention. 5A to 5C are diagrams illustrating a manner in which a sheet bundle Q is transported in the binding processing unit. 11A to 11C are diagrams illustrating a relationship between a binding process and a conveying state of the sheet bundle Q. 10A to 10C are diagrams illustrating change control of a jam detection time in the folding processing unit.

[Embodiment of Image Forming Apparatus]
First, an embodiment of the image forming apparatus according to the present invention will be described. FIG. 1 is an external view of a printer 10 as an embodiment of the image forming apparatus. The printer 10 includes a printer unit 100 as an image forming unit, a folding unit 200 functioning as a sheet processing unit, and a binding unit 300 functioning as a sheet processing unit and performing binding processing on a medium conveyed via the folding unit 200. Both the folding unit 200 and the binding unit 300 are units that cooperate with the printer unit 100. Note that FIG. 1 illustrates an example of an in-body discharge type printer 10, and the printer unit 100 has a function of selecting the folding unit 200 arranged in the body as a discharge destination of a recording medium (sheet P) on which an image is formed. The printer 10 also has a function of switching transport control so as to transport the recording medium to the binding unit 300 via the folding unit 200.

The binding processing unit 300 as an embodiment of the sheet processing device according to the present invention has a function of binding the ends of a stack of multiple sheets P in the folding processing unit 200 to form a sheet bundle Q. The folding processing unit 200 has a function of stacking multiple sheets P to be bound in the binding processing unit 300. As described below, the folding processing unit 200 has a circulating transport mechanism that circulates and transports the sheets P to stack them when forming the sheet bundle Q. The internal configuration of the folding processing unit 200 and the internal configuration of the binding processing unit 300 for performing these functions will be described below.

[Embodiment of Image Forming System]
2 is a diagram showing a schematic configuration of a printer system 1 as an embodiment of an image forming system according to the present invention. The printer system 1 is configured by connecting a printer 100a, a folding processing device 200a as a sheet processing device, and a binding processing device 300a as a sheet processing device. The printer system 1 operates to transport a sheet P on which an image is formed by the printer 100a to the folding processing device 200a, and to execute a predetermined overlapping and folding process in the folding processing device 200a. The printer system 1 also operates to overlap a plurality of sheets P on the sheet P on which an image is formed by the printer 100a in the folding processing device 200a, transport the sheet P to the binding processing device 300a, and execute the binding processing device by binding the ends of the sheets P.

[Functional configuration of control block]
Next, an embodiment of a control block for controlling the operations of the printer unit 100, the folding unit 200 as a sheet processing apparatus, and the binding unit 300 as a sheet processing apparatus according to this embodiment will be described with reference to FIG.

[Printer Unit 100 Control Block]
3, the printer unit 100 includes a printer control unit 110 as a control block. The printer control unit 110 includes a CPU (Central Processing Unit) 111, a ROM (Read Only Memory) 112, a RAM (Random Access Memory) 113, and a serial I/F 114.

The printer control unit 110 is connected to the image creation unit 120, image reading unit 130, and operation display unit 140. The image creation unit 120, image reading unit 130, and operation display unit 140 each include components for performing their respective functions. Each component of the image creation unit 120, image reading unit 130, and operation display unit 140 operates based on a control signal from the printer control unit 110.

The image creation unit 120 is configured to perform image formation processing based on image data on a sheet P, which is a sheet-shaped recording medium. The image reading unit 130 is configured to read an image formed on the sheet P to obtain image data. The operation display unit 140 has a function of serving both as an input unit for inputting operating conditions for the image creation unit 120 and the image reading unit 130, and as a display unit for displaying operation results, etc.

The operation display unit 140 also functions as a display unit for displaying the processing contents in the sheet processing control unit 210, and as an input unit for accepting input of setting information for controlling the operation (behavior) of the folding processing unit 200.

The control programs for controlling the image creation unit 120, the image reading unit 130, and the operation display unit 140 are stored in the ROM 112. The CPU 111 reads out the control programs stored in the ROM 112 and loads them in the RAM 113. The CPU 111 then stores data required for control in the RAM 113, and executes the control defined by the control programs while using the RAM 113 as a work area.

[Control block of the folding processing unit 200]
The folding unit 200 also includes a sheet processing control unit 210 as a control block. The sheet processing control unit 210 includes a CPU 211, a ROM 212, a RAM 213, and a serial I/F 214.

The sheet processing control unit 210 is connected to various loads 220 and various sensors 240. The various loads 220 are rollers and roller pairs, which will be described later. The rollers and roller pairs corresponding to the various loads 220 constitute conveying roller pairs and folding roller pairs, respectively. The various loads 220 are operated by drive motors that rotate each roller and each roller pair. The drive motors that constitute the various loads 220 are operated by a driver 230 that receives instructions from the sheet processing control unit 210. The various loads 220 are configured to perform operations including conveying control of the sheet P as a recording medium and folding processing of the sheet P.

The various sensors 240 are multiple sheet detection means that detect the position of the sheet P in the transport path, and are arranged in multiple locations in the transport path described below. The transport amount and position of the sheet P and sheet stack Q to be post-processed are determined by a predetermined control program executed by the sheet processing control unit 210 based on detection signals output from the various sensors 240 to the sheet processing control unit 210. The position of the sheet P is calculated by the sheet processing control unit 210 based on the amount of transport (transport distance) of the sheet P after the leading edge of the sheet P is detected by the sheet detection means, based on the amount of operation of the various loads 220.

The control program for the sheet processing control unit 210 to execute a predetermined processing function is stored in ROM 212. The CPU 211 reads out the control program stored in ROM 212 and loads it in RAM 213. The CPU 211 then stores data required for control in RAM 213, and executes control of the folding operation defined by the control program while using the RAM 213 as a work area. As described above, the sheet processing control unit 210 executes the control program stored in ROM 212, thereby enabling detection of sheet P and transport control of sheet P, which will be described later.

[Control block of binding processing unit 300]
3, the binding process unit 300 includes a binding process control unit 310 as a control block. The binding process control unit 310 includes a CPU 231, a ROM 312, a RAM 313, and a serial I/F 314.

The binding process control unit 310 is connected to a driver 330 that operates the transport rollers, the tapping roller R12, and the return roller R13 as various loads 320. The rollers as various loads 320 include the ninth transport means R9, the tenth transport means R10, the eleventh transport means R11, and a unit that performs the binding process, which will be described later.

The various loads 320 are operated by drive motors that rotate and drive each roller and each roller pair. The drive motors that make up the various loads 320 are operated by a driver 330 that receives instructions from the binding process control unit 310. The various loads 320 are configured to perform operations including transport control of the sheet P as a recording medium and binding processing of the sheet P.

The control program for the binding process control unit 310 to execute a predetermined processing function is stored in the ROM 212. The CPU 211 reads out the control program stored in the ROM 212 and loads it in the RAM 213. The CPU 211 then stores data required for control in the RAM 213, and executes control of the binding operation defined by the control program while using the RAM 213 as a work area. As described above, the binding process control unit 310 executes the control program stored in the ROM 212, thereby enabling detection of the sheet P and transport control of the sheet P, which will be described later.

The printer control unit 110 of the printer unit 100, the sheet processing control unit 210 of the folding processing unit 200, and the binding processing control unit 310 of the binding processing unit 300 are connected to each other via the serial I/F 114, serial I/F 214, and serial I/F 314 so that they can communicate with each other. Using this communication path, control commands and information required for recording medium transport control and the like are exchanged. The folding processing unit 200 switches between the presence and absence of folding processing based on the control command sent from the printer unit 100 and information about the sheet P. The folding processing unit 200 also switches between recording medium transport control and the type of folding processing based on the control command from the printer unit 100 and information about the position of the recording medium obtained from various sensors 240.

The information on the sheet P sent from the printer unit 100 (printer control unit 110) to the folding unit 200 (sheet processing control unit 210) includes multiple pieces of information. For example, multiple pieces of sheet type information indicating the type of sheet P transferred from the printer unit 100 to the folding unit 200, the thickness of the sheet P, the size of the sheet P, etc. are included. The information on the sheet P also includes information indicating the type of post-processing (such as folding processing or overlapping folding processing), information indicating the number of sheets P that make up a bundle in overlapping folding, and information indicating the folding position when folding processing. The control command notified from the printer control unit 110 to the sheet processing control unit 210 also includes a command corresponding to "overlap folding start notification" indicating whether the transferred sheet P corresponds to the last page (last sheet) of a unit that is processed as a whole.

[Internal configuration of the folding processing unit 200]
Next, the internal configuration of the folding processing unit 200 constituting a part of the sheet processing apparatus according to the present invention will be described. Fig. 4 is a schematic diagram showing the internal configuration of the folding processing unit 200. The folding processing unit 200 has a function of forming, while conveying, a sheet stack Q in which a plurality of sheets P, which are sheet-like media and serve as image formation targets discharged by the printer unit 100 arranged upstream, are stacked.

That is, the folding processing unit 200 is equipped with a plurality of conveying means that perform circular conveying to form the sheet bundle Q, and a plurality of conveying paths that form a conveying space for the sheet P and the sheet bundle Q by the conveying means. In addition, a plurality of sheet detection sensors are installed in each conveying path to detect the conveying position of the sheet P. Each sheet detection sensor is installed at a predetermined position for controlling the conveying of the sheet P and the sheet bundle Q described below. Note that each conveying means is composed of a conveying roller pair. That is, the sheet P and the sheet bundle Q are conveyed in a predetermined direction by the nip of each conveying roller pair. Furthermore, folding processing is performed on the sheet P and the sheet bundle Q depending on how they are fed into the nip of each conveying roller pair. Therefore, the plurality of conveying means also constitute a folding means.

The folding processing unit 200 has seven conveying paths. As shown in FIG. 4, it has a first conveying path W1 as an input conveying path, a second conveying path W2, a third conveying path W3, a fourth conveying path W4, a fifth conveying path W5, a sixth conveying path W6, and a seventh conveying path W7.

A plurality of roller pairs are arranged along each of the first conveying path W1, the second conveying path W2, the third conveying path W3, the fourth conveying path W4, the fifth conveying path W5, the sixth conveying path W6, and the seventh conveying path W7. That is, in the conveying path for conveying the sheet P, the roller pairs constituting the zeroth conveying means R0, the first conveying means R1, the second conveying means R2, the third conveying means R3, the fourth conveying means R4, the fifth conveying means R5, and the sixth conveying means R6 are arranged at their respective predetermined positions. The start and stop of rotation of each of these conveying roller pairs as conveying means is controlled by a control program executed by the sheet processing control unit 210. Through this control, the start and stop of conveying the sheet P are executed.

The folding processing unit 200 also includes a transport branching means for switching the transport direction of the sheet P. The transport branching means allows the folding processing unit 200 according to this embodiment to execute multiple transport processes on the sheet P that is brought in from upstream and held within the unit. The transport processes (transport modes) described below are processes that are switched in conjunction with the transport process of the sheet P.

The folding processing unit 200 has control functions to execute "discharge conveyance", "circulation conveyance" and "fold conveyance". "Discharge conveyance", "circulation conveyance" and "fold conveyance" are each conveyance processes of the sheet P etc. executed in the folding processing unit 200, and all of them are executed by the operation of each conveyance roller pair and the operation of the conveyance branching means. In other words, the control operation related to "discharge conveyance", the control operation related to "circulation conveyance" and the control operation related to "fold conveyance" are all executed by the control of the sheet processing control unit 210. In addition, each of these controls may be switched on or off based on a control command from the printer control unit 110.

The discharge transport is a transport process in which a sheet P transported from the upstream (printer unit 100) or a sheet P that has already been transported is circulated and transported to transport a sheet bundle Q that is overlapped with the succeeding sheet P, downstream (binding processing unit 300). At this time, no folding process is performed on the sheet P or the sheet bundle Q. In other words, "discharge transport" refers to transporting the sheet P or the sheet bundle Q in the same direction as the transport direction by the first transport means R1, and discharging it from the exit 22 to the binding processing unit 300 via the fourth transport means R4, the sixth transport means R6, and the eighth transport means R8.

Circulation transport is a transport process in which the sheet P or the sheet bundle Q is circulated to the upstream side (first transport path W1) of the first transport means R1 without changing the leading edge of the sheet P in the transport direction when transported along the first transport path W1, that is, without changing the leading edge of the sheet P in the transport direction by the first transport means R1. In other words, it means transporting the sheet P or the sheet bundle Q from the first transport path W1 to the second transport path W2 downstream in the transport direction. In addition, in "circulation transport", in order to return the sheet P sent to the second transport path W2 to the upstream of the first transport path W1, the sheet P is transported from the second transport path W2 to the third transport path W3 and circulated from the third transport path W3 to the first transport path W1. The transport path that circulates the sheet P is called the "circulation transport path". Circulation transport is performed when the number of sheets P that make up the sheet bundle Q has not reached a predetermined number. Furthermore, the circular transport is performed until the number of sheets P that make up the sheet bundle Q reaches the upper limit for the overlapping folding process and the control command notifying the start of overlapping folding is recognized by the sheet processing control unit 210.

"Folding conveyance" is a conveying process in which a predetermined folding position of the sheet P or the sheet bundle Q is sent to the nip of the first folding means F1. In other words, "folding conveyance" corresponds to conveyance in which the leading edge of the conveying direction by the first conveying means R1 is changed and the sheet P or the sheet bundle Q is sent from the first conveying path W1 to the second conveying path W2 downstream in the conveying direction. Therefore, in the folding conveyance, the part of the sheet P or the sheet bundle Q that is not the leading edge in the conveying direction when passing through the nip of the first conveying means R1 is sent to the second conveying path W2 as the leading edge in the conveying direction, and the leading edge in the changed conveying direction passes through the nip of the first folding means F1 to form a crease. In other words, the leading edge in the changed conveying direction (the leading edge in the conveying direction when sent into the second conveying path W2) becomes the crease. When forming a second crease, a part different from the leading edge in the conveying direction until then is sent to another conveying path as the new leading edge in the conveying direction. In this embodiment, the second crease is formed by sending it to the fifth conveying path W5. As described above, "folding and transporting" refers to transporting a sheet P or a sheet stack Q to form a fold.

The conveying branching means may also switch to convey the sheet from the first conveying path W1 to the fifth conveying path W5 via the second conveying path W2 and the third conveying path W3. The conveying control in this case is also included in the "folding conveying". As described above, the folding processing unit 200 is provided with multiple conveying paths so as to be able to switch between conveying that changes the leading edge of the sheet P or sheet stack Q in the conveying direction and conveying that does not change the leading edge in the conveying direction. The folding processing unit 200 is also provided with multiple conveying branching means so as to switch between these conveying paths.

[Description of Conveyor Branch Means]
The plurality of conveying/branching means are configured by a combination of a first conveying means R1, a fourth conveying means R4, a first folding means F1, a fifth conveying means R5, etc. For example, the plurality of conveying/branching means are configured as a first conveying/branching means J1, a second conveying/branching means J2, and a third conveying/branching means J3, as shown in FIG. 5. These plurality of conveying/branching means are included in various loads 220 whose operation is controlled by the sheet processing control unit 210. Therefore, the sheet processing control unit 210 controls the operation of the conveying means that conveys the sheet P and the sheet stack Q by controlling the operation of the plurality of conveying/branching means, and controls selective switching of the plurality of conveying paths. In addition, a first folding means F1 and a second folding means F2 for folding the sheet P and the sheet stack Q are also arranged in the middle of the circulating conveying path.

In the following description, the sheet P (leading sheet P) that is first transported from the printer unit 100 to the folding processing unit 200 is referred to as the "leading sheet P1". The sheet P that is transported following the leading sheet P1 is referred to as the "following sheet P2". The sheet P that is transported following the following sheet P2 is referred to as the "next sheet P3". Therefore, in the sheet stack Q formed by circulating transport, when multiple sheets P are stacked, the lowest sheet is the leading sheet P1. The top surface is the following sheet P2 or the next sheet P3, or the following sheet Pn.

[Description of each conveying means]
In the folding processing unit 200, a zeroth conveying means R0 serving as an inlet conveying roller pair is disposed near the inlet 21 that receives the sheet P from the printer unit 100. In the zeroth conveying means R0, a drive motor that rotates and drives the zeroth conveying means R0 starts to rotate under the control of the sheet processing control section 210 that receives information notifying that the preceding sheet P1 has been discharged from the printer unit 100. Thereafter, when the leading edge of the preceding sheet P1 reaches the nip of the roller pair of the zeroth conveying means R0, the zeroth conveying means R0 conveys the preceding sheet P1 downstream.

The first conveying means R1 is arranged along the first conveying path W1 provided downstream of the zeroth conveying means R0, and is made up of a pair of rollers having a nip that holds the conveyed preceding sheet P1, and conveys the preceding sheet P1 downstream.

The first conveying means R1 also functions as a skew correction means that abuts the leading edge of the preceding sheet P1 conveyed from upstream against the nip to correct the inclination of the posture of the preceding sheet P1 in the conveying direction. The first conveying means R1 performs skew correction to correct the disturbance of the conveying posture of the sheet P (preceding sheet P1) conveyed from the zeroth conveying means R0 to the first conveying means R1. When performing this skew correction, the rotation of the conveying roller pair performed as the conveying operation is temporarily stopped, or the conveying roller pair is controlled to rotate in the reverse direction, which is the reverse operation of the normal conveying operation. If the conveying roller pair constituting the first conveying means R1 is rotated in the reverse direction when the skew correction is performed, the reverse rotation of the conveying roller pair is stopped when the preceding sheet P1 abuts against the nip. After that, the conveying roller pair starts rotating (forward rotation) at a predetermined timing to convey the preceding sheet P1 downstream.

Skew correction is performed only when folding the sheet bundle Q of overlapping sheets P. When performing post-processing other than folding, i.e., binding downstream of conveying the sheet bundle Q out of the folding unit 200, skew correction as described above is not performed in the transport control for forming the sheet bundle Q by circularly conveying the sheets P.

The first folding means F1 is disposed between the first conveying path W1 and the second conveying path W2, facing each other, and forms a nip between them. The preceding sheet P1 is guided from the first conveying path W1 to the second conveying path W2 through the conveying path guided by this nip. Note that conveying control in which the preceding sheet P1 passes through the first folding means F1 without changing the leading edge in the conveying direction in the first conveying means R1 corresponds to "circular conveying". Also, conveying control in which the leading edge in the conveying direction of the preceding sheet P1 when guided by the nip of the first folding means F1 and passing through the conveying path is a part different from the leading edge in the conveying direction in the first conveying means R1 corresponds to "folding conveying". The folding processing unit 200 switches whether the leading edge in the conveying direction of the preceding sheet P1 when passing through the first folding means F1 is the same as when passing through the nip of the first conveying means R1 or a different part by the operation of multiple conveying roller pairs.

Furthermore, the third transport means R3 guides the preceding sheet P1 led to the second transport path W2 to the third transport path W3 for circular transport, and temporarily stops the transport of the preceding sheet P1 on the third transport path W3. Transport of the preceding sheet P1 temporarily stopped on the third transport path W3 is resumed when the succeeding sheet P2 is received from the printer unit 100. This allows the preceding sheet P1 to return to the upstream side of the first transport means R1 on the first transport path W1, and to merge with and overlap the succeeding sheet P2 at a predetermined position on the first transport path. The circular transport path is configured as described above.

In the circulating conveying path described above, the preceding sheet P1 and the succeeding sheet P2 are overlapped to form the sheet bundle Q. Next, the flow of performing the folding process (overlap folding process) on the sheet bundle Q will be described with reference to Figures 4 and 5.

The folding process for the sheet stack Q is mainly performed by the first folding means F1, which operates under control after the sheet processing control unit 210 acquires an "overlap folding process start instruction" notified by the printer control unit 110. Then, the sheet stack Q that has been folded (overlap folding process) by the first folding means F1 is transferred from the second conveying path W2 to the fifth conveying path W5 and discharged. The fourth conveying means R4, the fifth conveying means R5 and the first folding means F1 are driven by the same drive motor. The drive motor can rotate in the forward and reverse directions. By switching the rotation direction of the drive motor, it is possible to switch between circulating and folding the sheet stack Q, which is made up of the preceding sheet P1 and the succeeding sheet P2 overlapping each other.

In addition, a branching claw 23 is disposed downstream in the conveying direction of the sixth conveying means R6. The branching claw 23 appropriately switches between guiding the sheets P (sheet stack Q) to the sixth conveying path W6 side and guiding the sheets P (sheet stack Q) to the seventh conveying path W7 side. The conveying direction is switched by changing the position of the branching claw 23. The position of the branching claw 23 can be changed by, for example, a solenoid. Note that a drive mechanism including a motor, gears, cams, etc. can be used instead of a solenoid.

The sheet P that has passed through the fourth conveying path W4 or the fifth conveying path W5 is discharged and stacked on the discharge tray 24 of the folding processing unit 200. The seventh conveying path W7 is a path for delivering the sheet P to the post-processing device when the post-processing device is provided downstream of the folding processing unit 200 in the image forming system. The post-processing device performs post-processing such as alignment and binding on the sheet P that has been folded or the sheet P that has not been folded.

A first sheet detection sensor SN1 is disposed downstream of the zeroth conveying means R0 in the first conveying path W1. A second sheet detection sensor SN2 is disposed upstream of the first conveying means R1 in the first conveying path W1. The second sheet detection sensor SN2 is disposed downstream of the first sheet detection sensor SN1 in the first conveying path W1.

In the third transport path W3 that constitutes the circulatory transport path, a third sheet detection sensor SN3 is arranged downstream of the second transport means R2 (downstream in the transport direction during circulatory transport). In addition, in the third transport path W3, a fourth sheet detection sensor SN4 is arranged downstream of the third transport means R3 (downstream in the transport direction during circulatory transport).

In the fourth transport path W4, which constitutes the transport path for sheet P during discharge transport, a fifth sheet detection sensor SN5 is arranged downstream of the fourth transport means R4 (downstream in the transport direction during discharge transport). In the fifth transport path W5, a sixth sheet detection sensor SN6 is arranged downstream of the fifth transport means R5 (downstream in the transport direction during discharge transport). In the sixth transport path W6, a seventh sheet detection sensor SN7 is arranged downstream of the sixth transport means R6 (downstream in the transport direction during discharge transport).

[Example of overlapping operation]
Next, a process of forming the sheet bundle Q using the circulating transport by the folding unit 200 will be described with reference to FIGS.

First, FIG. 5 shows the initial state before the sheet P is transported from the printer unit 100 side. In the state shown in FIG. 5, when the leading edge of the preceding sheet P1 transported from the printer unit 100 side reaches the paper discharge outlet of the printer unit 100, the zeroth transport means R0 starts to rotate under the control of the sheet processing control unit 210.

Next, as shown in FIG. 6, the preceding sheet P1 is transported to the first transport path W1 by the rotation of the zeroth transport means R0. Furthermore, in order to perform "circulation transport" in which the preceding sheet P1 is transported to the second transport path W2 and then guided to the circulation transport path, rather than "discharge transport" in which the preceding sheet P1 is guided to the fourth transport path W4, the sheet processing control unit 210 moves the first transport branch means J1 to the position shown in FIG. 6.

When the leading edge of the preceding sheet P1 transported by the zeroth transport means R0 is detected by the first sheet detection sensor SN1 arranged upstream of the first transport means R1, the detection signal is notified to the sheet processing control unit 210. The sheet processing control unit 210 then calculates the timing at which the position of the leading edge of the sheet P protrudes from the nip position of the first transport means R1 by a predetermined amount (protrusion amount) after receiving the detection signal for the sheet P. The first transport means R1 starts to rotate at the timing at which the leading edge of the sheet P reaches the abutment amount (first abutment amount Δ1) from the nip position of the first transport means R1.

When the leading edge of the preceding sheet P1 enters the nip of the first conveying means R1, the sheet processing control unit 210 rotates the first folding means F1, the second conveying means R2, and the third conveying means R3.

Then, as shown in FIG. 7, the preceding sheet P1 is transported to the second transport path W2 by the operation of the first transport means R1 and the first folding means F1, and is transported to the second transport means R2 along the downward slope of the second transport path W2. Then, the preceding sheet P1 is transported to the third transport path W3 by the operation of the second transport means R2. The preceding sheet P1 transported to the third transport path W3 is further transported by the third transport means R3. When the fourth sheet detection sensor SN4 detects the leading edge of the preceding sheet P1 transported by the third transport means R3, a detection signal is notified from the fourth sheet detection sensor SN4 to the sheet processing control unit 210. After receiving the detection signal from the fourth sheet detection sensor SN4, the sheet processing control unit 210 calculates the timing at which the leading edge of the preceding sheet P1 reaches a position corresponding to the second protrusion amount Δ2 by the third transport means R3 from the position of the fourth sheet detection sensor SN4.

In other words, by setting the position of the first conveying branching means J1 to the position illustrated in FIG. 6, the leading edge of the preceding sheet P1 can be conveyed downstream without changing the conveying direction when passing through the first conveying means R1. This conveying control executes circular conveying of the preceding sheet P1.

As shown in FIG. 8, when it is determined that the leading edge of the preceding sheet P1 has reached a position corresponding to the second protrusion amount Δ2, the rotation of the first folding means F1, the second conveying means R2, and the third conveying means R3 is stopped, and the circular conveying of the preceding sheet P1 is temporarily stopped.

Even when the transport of the preceding sheet P1 is stopped, the first transport means R1 continues to rotate in order to receive the succeeding sheet P2 that is next transported from the printer unit 100.

Next, as shown in FIG. 9, after the sheet processing control unit 210 is notified of a detection signal indicating that the leading edge of the succeeding sheet P2 has been detected by the first sheet detection sensor SN1, the sheet processing control unit 210 resumes conveying the preceding sheet P1 at a predetermined timing calculated based on the detection timing of the first sheet detection sensor SN1 while conveying the succeeding sheet P2. This causes the succeeding sheet P2 and the preceding sheet P1 to overlap at a predetermined position (overlap position) in the first conveying path W1. The overlapping state at this time is such that the leading edge of the succeeding sheet P2 in the conveying direction is slightly ahead of the leading edge of the preceding sheet P1 in the conveying direction.

The sheet stack Q, which is made up of the succeeding sheet P2 and the preceding sheet P1 superimposed on each other, is transported to the nip of the first transport means R1. This timing corresponds to the timing at which the leading edge of the succeeding sheet P2 reaches a position equivalent to the third protrusion amount Δ3 when it joins with the preceding sheet P1. That is, when the leading edge of the succeeding sheet P2 reaches a position equivalent to the third protrusion amount Δ3, the sheet processing control unit 210 resumes the rotation of the second transport means R2 and the third transport means R3. This resumes the transport of the preceding sheet P1, which had been stopped, as shown in FIG. 9.

In this case, the sheet processing control unit 210 does not stop the transport of the subsequent sheet P2, but calculates the timing to resume transport of the preceding sheet P1 from the detection of the first sheet detection sensor SN1. Then, when the transport resumption timing arrives, it resumes transport of the preceding sheet P1. With this control, the subsequent sheet P2 and the preceding sheet P1 are transported in an overlapping state. In this overlapping transport state, the leading edge of the subsequent sheet P2 is slightly ahead of the leading edge of the preceding sheet P1 in the transport direction toward the first transport means R1.

The third protrusion amount Δ3 is calculated based on the speed (motor speed) of the motor driving the zeroth conveying means R0, the motor speed of the motor driving the third conveying means R3, and the positional relationship (mutual distance) between the first sheet detection sensor SN1, the second sheet detection sensor SN2, and the fourth sheet detection sensor SN4. The third protrusion amount Δ3 corresponds to the amount (leading amount) by which the leading edge of the following sheet P2 in the conveying direction leads the leading edge of the preceding sheet P1 in the conveying direction when the leading edges of the preceding sheet P1 and the following sheet P2 join in front of the first conveying means R1.

Then, the leading edge of the preceding sheet P1 and the leading edge of the following sheet P2 join together to generate a sheet stack Q, which passes through the nip of the first conveying means R1 and is conveyed downstream as shown in FIG. 10. As described above, the following sheet P2 is controlled to strike the nip of the first conveying means R1 first, and then the preceding sheet P1 strikes the nip of the first conveying means R1. This makes it possible to adjust the timing of merging even if the third protrusion amount Δ3 is large and the sheets have not yet joined before the second sheet detection sensor SN2.

Then, the sheet processing control unit 210 judges whether the overlapping folding number setting notified by the printer unit 100 matches the number of sheets received, and if they match, performs the folding process described below. If they do not match, the process from FIG. 7 to FIG. 9 is performed again, and the next sheet P3 (the sheet P next to the succeeding sheet P2) conveyed from the printer unit 100 side is merged with the sheet stack Q and overlapped. Note that whether the sheet P has been conveyed to just before the nip of the second conveying means R2 can be determined, for example, from the number of driving steps of the motor driving the first conveying means R1. Therefore, the driving motor that rotates and drives each conveying means may be a stepping motor or the like. Note that a DC motor can also be applied if it is controlled based on the timing calculated by the detection of each sensor.

[First embodiment of binding process]
Next, a first embodiment of the binding process performed in the folding process unit 200 and the binding process unit 300 as the sheet processing device according to the present invention will be described. In this embodiment, a plurality of sheets P are overlapped using a circulating conveyance path provided in the folding process unit 200 to form a sheet bundle Q, and the binding process is performed on this sheet bundle Q in the binding process unit 300. In the binding process according to this embodiment, the alignment of the end of the sheet bundle Q formed by the circulating conveyance can be improved. Hereinafter, the description will be given with reference to FIG. 12 and subsequent figures. In the following description, the sheet bundle Q is an example that is composed of a preceding sheet P1 and a succeeding sheet P2. In each figure, the preceding sheet P1 is indicated by a dashed line, and the succeeding sheet P2 is indicated by a dotted line. It is assumed that the sheet bundle Q has the succeeding sheet P2 overlapped on the preceding sheet P1.

Figure 12 shows the internal configuration of the folding processing unit 200 already described and the binding processing unit 300 provided downstream of it. Details of the folding processing unit 200 are omitted.

The binding processing unit 300 is configured to transport the sheet stack Q discharged through the outlet 22 (see FIG. 4) of the folding processing unit 200 to the staple tray 31 via the ninth transport means R9, the tenth transport means R10, and the eleventh transport means R11.

The sheet stack Q transported to the staple tray 31 by the eleventh transport means R11 moves from the rear end side in the transport direction toward the reference fence 32, where the end is aligned. At this time, a striking roller 33 rotates while in contact with the top surface of the sheet stack Q transported to the staple tray 31, urging the sheet stack Q to move toward the reference fence 32. Then, a return roller 34 arranged near the reference fence 32 pushes the sheet stack Q toward the reference fence 32, aligning the end.

The topmost sheet of the sheet stack Q transported toward the staple tray 31 is the rear sheet Pn. In the following, to simplify the explanation, a sheet stack Q consisting of a leading sheet P1 and a trailing sheet P2 is used as an example. It is assumed that the leading edge of the sheet stack Q in the transport direction when it passes through the eleventh transport means R11 is the end of the leading sheet P1 as shown in FIG. 13(a) or the end of the trailing sheet P2 as shown in FIG. 13(b).

When the sheet stack Q conveyed in the state shown in FIG. 13(a) is conveyed to the staple tray 31, the topmost succeeding sheet P2 comes into contact with the tapping roller 33 and the return roller 34 and abuts against the reference fence 32, as shown in FIG. 14(a). When the leading sheet P1 is conveyed to the staple tray 31, if the end of the leading sheet P1 in the conveying direction is ahead of the end of the following sheet P2 in the conveying direction, the action of the tapping roller 33 and the return roller 34 causes the following sheet P2 to abut against the reference fence 32 first. In this case, even if the tapping roller 33 and the return roller 34 continue to apply a force to the following sheet P2 to move it toward the reference fence 32, the following sheet P2 does not move. As a result, the leading sheet P1 cannot obtain a force to move toward the reference fence 32, and the conveying direction ends of the leading sheet P1 and the following sheet P2 are not aligned.

On the other hand, when the sheet stack Q transported in the state shown in FIG. 13(b) is transported to the staple tray 31, the above-mentioned alignment disturbance can be suppressed. In other words, if the sheet stack Q is transported to the staple tray 31 with the end of the succeeding sheet P2 in the transport direction preceding the end of the preceding sheet P1 in the transport direction, as shown in FIG. 14(b), the action of the striking roller 33 and the return roller 34 causes the preceding sheet P1 to abut against the reference fence 32 before the succeeding sheet P2 abuts against the reference fence 32. As a result, each sheet P (the preceding sheet P1 and the succeeding sheet P2) constituting the sheet stack Q can abut against the reference fence 32, so that the ends in the transport direction are aligned.

In light of the above, the problems with the conventional technology will be explained. In the conventional technology, the edges of the sheets P are controlled to be aligned, and the sheets are transported to a position for performing post-processing, such as the staple tray 31. However, when the sheets P are overlapped using a circular transport path, misalignment during overlapping can cause the preceding sheet P1 to be transported first. This raises concerns that the alignment at the staple tray 31 may be incomplete, as shown in the examples of Figures 13(a) and 14(a).

The amount of misalignment of the edges of the sheets P varies depending on factors such as the timing of conveyance being shifted due to the degree of bending of the edges of each sheet P when overlapping, and on the variations in detection by the various sensors 240. When three or more sheets P are overlapped by circulating conveyance, the amount of misalignment also varies depending on the inner wheel difference of the conveyance path in the circulating conveyance path (the inner sheet P is ahead). Misalignment may also occur between the sheets P while the sheet stack Q is being conveyed from the folding unit 200 to the staple tray 31 of the binding unit 300.

Therefore, in the folding processing unit 200 and binding processing unit 300 according to this embodiment, friction between multiple sheets P (inter-sheet friction), slippage due to differences in the conveying force between the drive roller and driven roller of each conveying means, etc. are taken into consideration. Taking these into consideration, when overlapping the sheets P in the circulating conveying path, conveying control is performed so that the succeeding sheet P2 is overlapped ahead of the preceding sheet P1 in the conveying direction.

Specifically, as described in FIG. 8, after the leading edge of the preceding sheet P1 in the conveying direction is detected by the fourth sheet detection sensor SN4, conveying is stopped when the leading edge of the preceding sheet P1 reaches a position equivalent to the second protrusion amount Δ2 for overlapping purposes.

Next, as described in FIG. 9, after a detection signal indicating that the leading edge of the succeeding sheet P2 has been detected by the first sheet detection sensor SN1 is notified to the sheet processing control unit 210, the succeeding sheet P2 is conveyed while the conveyance of the preceding sheet P1 is resumed at a predetermined timing calculated based on the detection timing of the first sheet detection sensor SN1.

Then, the sheet stack Q in which the succeeding sheet P2 and the preceding sheet P1 are overlapped is transported to the nip of the first transport means R1, and this transport timing corresponds to the timing when the leading edge of the succeeding sheet P2 reaches a position equivalent to the third protrusion amount Δ3 when it joins with the preceding sheet P1. That is, when the leading edge of the succeeding sheet P2 reaches a position equivalent to the third protrusion amount Δ3, the sheet processing control unit 210 resumes the rotation of the second transport means R2 and the third transport means R3. This resumes the transport of the preceding sheet P1, whose transport had been stopped, as described in FIG. 9.

The second protrusion amount Δ2 and the third protrusion amount Δ3 that triggers the restart of conveying are such that the second protrusion amount Δ2 is greater than the third protrusion amount Δ3 (third protrusion amount Δ3 < second protrusion amount Δ2).

By delaying the timing of re-transporting the preceding sheet P1, the subsequent sheet P2 is controlled to be reliably in a state leading the preceding sheet P1 when overlapped with the subsequent sheet P2. This allows the subsequent sheet P2 to be transported to the staple tray 31 in a leading state when binding the sheet stack Q formed by overlapping processing using circular transport. As a result, as described above, the alignment operation by the striking rollers 33 and return rollers 34 allows each end of the sheets P that make up the sheet stack Q to abut against the reference fence 32, allowing for highly consistent binding processing.

[Second embodiment of binding process]
Next, a second embodiment of the binding process performed in the folding process unit 200 and the binding process unit 300 as the sheet processing apparatus according to the present invention will be described. In this embodiment, a plurality of sheets P are overlapped using a circulating conveyance path provided in the folding process unit 200 to form a sheet bundle Q, and the sheet bundle Q is bound in the binding process unit 300.

When the sheet bundle Q is formed by circular transport and transported to the binding processing unit 300, as already explained, the transport is controlled so that the sheet bundle Q is formed in a state in which the leading edge of the preceding sheet P1 precedes the leading edge of the succeeding sheet P2 in the transport direction. In this case, the length in the transport direction of the sheet bundle Q while being transported to the binding processing unit 300 (transport length) appears longer than the transport length of the sheet P.

For example, the apparent transport length "Lm" of the stack of sheets Q compared to the transport length of sheet P is the sum of "Lg", which is the gap between the leading edge positions of the preceding sheet P1 and the succeeding sheet P2, and the transport length of each sheet P. If jam detection by the fifth sheet detection sensor SN5 is performed for the normal time (the time it takes to detect one sheet P) for this apparent transport length Lm, there will be less margin for slippage.

While sheet P or sheet stack Q passes the installation position of the fifth sheet detection sensor SN5, it continues to detect them, and the sheet processing control unit 210 judges the passing time of sheet P or sheet stack Q based on the detection signal. If this passing time does not exceed a predetermined threshold time, it is determined that transport is proceeding normally. On the other hand, if the passing time exceeds the threshold time, it is determined that a transport abnormality such as a jam has occurred. The sheet processing control unit 210 changes this threshold time for jam detection according to the sheet stack Q.

As shown in FIG. 15, when the sheet stack Q is being transported in the fourth transport path W4 and the seventh transport path W7 as the discharge transport paths, the judgment conditions for detecting a transport failure are changed based on the time until the fifth sheet detection sensor SN5 and the eighth sheet detection sensor SN8 no longer detect the sheet stack Q.

For example, the judgment condition (jam detection time) for detecting a transport abnormality of one sheet P is set to a value obtained by multiplying the detection time based on the transport length of sheet P by a coefficient (e.g., 1.2). In other words, "jam detection time when transporting one sheet P = transport time based on the transport length of sheet P x 1.2." Here, "transport time based on the transport length of sheet P" refers to, for example, the time from when the fifth sheet detection sensor SN5 detects the leading edge of sheet P to when it no longer detects sheet P. In other words, a transport abnormality is detected based on the transport length in the transport direction.

The transport is controlled so that the jam detection time when transporting a stack Q of multiple overlapping sheets P is the transport length of each sheet P plus the transport time of the misalignment amount Lg multiplied by a coefficient (1.2). In other words, "jam detection time when transporting a stack of sheets Q = (transport length of sheet P + transport time based on misalignment margin B) x 1.2." Here, "misalignment margin B" is twice the misalignment amount Lg. Note that the misalignment amount Lg is a value that is preset according to the type of sheet P.

Therefore, the margin B can be increased according to the number of sheets P that form the sheet stack Q, i.e., the number of overlaps. For example, the margin B when setting the jam detection time for a sheet stack Q formed of two sheets P is twice the misalignment amount Lg, but the margin B when setting the jam detection time for a sheet stack Q formed of three sheets P is three times the misalignment amount Lg.

This allows the optimal jam detection time to be set depending on the configuration of the sheet stack Q, eliminating the need to deal with unnecessary jams.

As described above, in the sheet processing device configured with the folding processing unit 200 and the binding processing unit 300 according to this embodiment, when performing binding processing on a sheet bundle Q in which multiple sheets P are stacked using a circulating transport path, the subsequent sheet P2 is moved ahead. As a result, when aligning the ends in the staple tray 31, the topmost sheet P (subsequent sheet P2) is the last to abut against the reference fence 32. In other words, by increasing the amount of abutment movement of the subsequent sheet P2 to the reference fence 32, the other sheets P that make up the sheet bundle Q reach the reference fence 32 first, improving the degree of alignment of the sheet bundle Q.

The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the technical gist of the invention. All technical matters included in the technical ideas described in the claims are covered by the present invention. The above-described embodiments are preferred examples, but a person skilled in the art can realize various modifications from the disclosed contents. Such modifications are also included in the technical scope described in the claims.

1: Printer system 10: Printer 31: Staple tray 32: Reference fence 33: Striking roller 34: Return roller 100: Printer unit 100a: Printer 110: Printer control unit 200: Folding unit 200a: Folding device 210: Sheet processing control unit 300: Binding unit 300a: Binding device 310: Binding control unit

JP 2014-125312 A

Claims (5)

A sheet processing apparatus having a circulating conveying path that conveys and stacks a plurality of sheets to be conveyed as a sheet bundle,
the circulating conveying path being provided midway between the sheet carry-in conveying path and the sheet stack carry-out conveying path;
A control unit that controls a conveying operation of the sheet and the sheet stack;
Equipped with
the control unit controls a conveying operation of the plurality of sheets such that, when conveying the sheet bundle through the discharge conveying path, a leading edge of a preceding sheet, which is conveyed first from the conveying conveying path, among the sheets forming the sheet bundle, is positioned ahead of a leading edge of a succeeding sheet, which is conveyed after the preceding sheet, in the conveying direction.
A sheet processing apparatus comprising: a sensor for detecting a conveyance failure in the discharge conveyance path,
the control unit detects a passing time of the sheet or the sheet bundle on the discharge conveyance path based on a time during which the sensor detects the sheet or the sheet bundle, and determines that a conveyance abnormality has occurred when the passing time exceeds a predetermined threshold time;
a threshold time for conveying the sheet stack is set to be longer than a threshold time for conveying the sheets via the discharge conveying path;
The sheet processing apparatus according to claim 1 . the control unit changes the threshold time in accordance with the number of the sheets forming the sheet bundle.
The sheet processing apparatus according to claim 2 . An image forming apparatus including an image forming unit that forms an image on a sheet, and a sheet processing unit that performs post-processing on the sheet,
4. An image forming apparatus, comprising: a sheet processing unit configured to process a sheet of a first material; 4. An image forming system comprising: an image forming apparatus including an image forming section for forming an image on a sheet; and the sheet processing apparatus according to claim 1, which is connected to the image forming apparatus.