JP2009274822A - After-treatment device and image forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an after-treatment device with an after-treatment part for executing good after-treatment while neatly aligning a plurality of sheets at their ends even when carrying two sheets overlapping each other. <P>SOLUTION: To execute after-treatment such as binding treatment while neatly aligning the sheets at their ends, two sheets S1, S2 overlapping each other are carried in such a manner that the upper-side sheet S1 precedes the lower-side sheet S2. The rotating speed of a first roller RT1 for contacting the upper-side sheet S1 is set to be higher than the rotating speed of a second roller RT2 for contacting the lower-side sheet S2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a post-processing device that performs post-processing such as binding processing on a sheet, and an image forming system including the post-processing device.

  2. Description of the Related Art A post-processing device that performs post-processing such as binding processing or punching processing on an image-formed sheet output from an image forming apparatus such as a copying machine or a printer is known. The post-processing apparatus is connected to the image forming apparatus to constitute an image forming system, and is linked to the operation of the image forming apparatus. Therefore, for an image forming apparatus that forms an image on a sheet at a high speed, a high-speed post-processing apparatus that can follow the processing speed of the image forming apparatus is required.

  By the way, since the post-processing apparatus executes post-processing such as binding processing and punching processing on a sheet, the next sheet is executed at the position where the post-processing is performed (post-processing unit) while the post-processing is being executed. Can not accept. On the other hand, in order not to reduce the productivity of the sheet output from the image forming apparatus, it is necessary to accept the sheet output from the image forming apparatus by the post-processing apparatus even during the post-processing.

  Therefore, a post-treatment in which the sheet output from the image forming apparatus is temporarily stopped on the upstream side of the post-processing unit, and the sheet is overlapped with the next sheet of the stopped sheet and then conveyed to the post-processing unit. There is a device. With such a form of the post-processing apparatus, it is possible to secure a time for executing the post-processing by widening the sheet conveyance interval, and the sheet output from the image forming apparatus can be processed even during the post-processing. Can accept.

  Here, in the post-treatment apparatus that transports two sheets in a stacked manner, the alignment of the sheet end portion in the post-processing unit is examined. FIG. 8 is an explanatory diagram showing an outline of a general post-processing unit that executes the binding process.

  As shown in FIG. 8, the sheet S that is transported in an overlapping manner is transported in the X direction by the transport roller R and discharged to a position as indicated by a broken line. Then, the sheet S moves in the Y direction due to its own weight, and the end SE of the sheet S (the end on the upstream side in the conveyance direction in the sheet S) comes into contact with the alignment plate SP and stops. The sheets S that are aligned and stacked by the alignment plate SP are subjected to binding processing by the binding processing unit ST that is a post-processing unit. A part of the booklet subjected to the binding process is produced by such an operation.

  FIG. 9 is an enlarged view around the alignment plate SP. As shown in FIG. 8, the end portions of the two sheets S discharged by the transport roller R are aligned on the alignment plate SP, but the end portions of the two sheets S transported in a stacked manner are aligned. If the sheet is discharged from the conveying roller R in the absence, the end of the upper sheet S1 and the end of the lower sheet S2 may deviate and move in the Y direction as shown by the broken line in FIG. is there. In the state shown by the broken line in FIG. 9, since the upper sheet S1 comes into contact with the alignment plate SP before the lower sheet S2, the lower sheet S2 is sandwiched between the sheets to the alignment plate SP. Movement is restricted, and the end of the lower sheet S2 does not come into contact with the alignment plate SP. If it becomes such a state, the edge part of the sheet | seat S will not align, but even if it performs a binding process, the booklet of the beautiful external appearance with which the edge part was aligned cannot be produced.

In view of this, a technique has been proposed in which two sheets transported in an overlapping manner are shifted so that the sheet end portions are neatly aligned on the alignment plate SP. In the technique described in Patent Document 1, a plurality of conveyance paths are formed in the middle of the conveyance path of the post-processing apparatus, two sheets are stacked, and the upper sheet is stacked so that the upper sheet precedes the lower sheet. It is a technology of conveying. In this way, the state as shown in FIG. 9 is avoided, and the end of the lower sheet S2 is positioned before the end of the upper sheet S1 around the alignment plate SP as shown in FIG. It can be brought into contact with SP. As a result, it is possible to produce a booklet with a beautiful appearance in which the end portions of the sheets are aligned.
Japanese Patent Laid-Open No. 11-157741

  However, the technique described in Patent Document 1 is configured to stack the upper sheet in a form preceding the lower sheet at a position away from the binding processing unit, which is a post-processing unit, and then transport the sheet to the binding processing unit. The positional relationship between the two sheets may be shifted. As a result, the relationship between the two conveyed sheets may not be as shown in FIG. 10 but may be as shown in FIG. 9, so that the end portions of the sheets can be reliably aligned. Absent.

  Accordingly, an object of the present invention is to provide a post-processing apparatus and an image forming system that can execute good post-processing by aligning the end portions of a plurality of sheets neatly in the post-processing unit even when two sheets are stacked and conveyed. It is to provide.

In order to achieve the above object, a post-processing apparatus according to the present invention includes:
A transport unit for transporting two stacked sheets;
A post-processing unit that performs post-processing on a sheet conveyed by the conveyance unit;
A pair of rollers that receive the two sheets conveyed by the conveyance unit, and precede the upper sheet of the two sheets to pass the two sheets to the post-processing unit;
It is characterized by having.

The image forming system according to the present invention includes:
It has the post-processing device and an image forming device for forming an image on a sheet.

  According to the post-processing apparatus and the image forming system according to the present invention, even when two sheets are stacked and conveyed, the end portions of the plurality of sheets are neatly aligned in the post-processing unit, and good post-processing is executed. I can do it.

  FIG. 1 is an overall configuration diagram of an image forming system including a large-capacity sheet feeding device LT, an image forming apparatus A, and a post-processing apparatus B. The post-processing apparatus B includes an intermediate transport unit B1 and a post-processing unit B2.

  [Large-capacity paper feeding device LT] The large-capacity paper feeding device LT includes a sheet stacking unit 7A, a first paper feeding unit 7B, and the like. In the sheet stacking portion 7A, a large amount of sheets S of A4 size, A3 size, etc. are stored. The sheets S stored in the sheet stacking unit 7A are continuously fed into the image forming apparatus A.

  [Image Forming Apparatus A] The image forming apparatus A includes an image reading unit 1, an image writing unit 3, an image forming unit 4, a paper feeding and conveying unit 5, a fixing unit 6, an automatic document conveying unit A2, an operation display unit A4, and the like. It is configured.

  The image forming unit 4 includes a photosensitive drum 4A, a charging unit 4B, a developing unit 4C, a transfer unit 4D, a separation unit 4E, a cleaning unit 4F, and the like. The paper feeding unit 5B, the second paper feeding unit 5C, the transport unit 5D, the paper discharge unit 5E, and the automatic duplex copying paper feeder (ADU) 5F are configured.

  The operation display unit A4 includes a touch panel in which a touch screen is arranged on a display unit configured by a liquid crystal panel. Various setting screens can be displayed through the operation display unit A4, and the type of post-processing or the type of sheets stored in the paper feed cassette 5A can be input.

  A document placed on the document table of the automatic document feeder A2 is read on one or both sides of the document by the optical system of the image reading unit 1, and the photoelectrically converted analog signal is A / D converted, After undergoing processing such as shading correction and image compression processing, the image is sent to the image writing unit 3.

  The output light from the semiconductor laser in the image writing unit 3 is applied to the photosensitive drum 4A of the image forming unit 4, and an electrostatic latent image is formed on the photosensitive drum 4A. The electrostatic latent image formed on the photosensitive drum 4A is subjected to processing such as charging, exposure, development, transfer, separation, and cleaning in the image forming unit 4.

  The image is transferred by the transfer unit 4D to the sheet S conveyed by the first paper supply unit 5B, and the image on the sheet S is fixed on the sheet S by the fixing unit 6. The fixed sheet S is sent to the post-processing apparatus B from the paper discharge unit 5E. When images are formed on both sides of the sheet S, the front and back are reversed by the automatic double-sided copy paper feeder 5F after the sheet S is fixed, and sent again to the image forming unit 4 to form an image. It is sent to the processing device B.

  Note that the image forming apparatus A in FIG. 1 forms a monochrome image on the sheet S, but may form a color image on the sheet S.

  [Post-Processing Apparatus B] As described above, the post-processing apparatus B includes the intermediate conveyance unit B1 that superimposes sheets and the post-processing unit B2 that performs binding processing. In the present embodiment, the intermediate transport unit B1 is a casing independent of the post-processing unit B2, but the intermediate transport unit B1 and the post-processing unit B2 may be the same casing.

  The intermediate conveyance unit B1 includes a sheet carry-in unit 11, a stacking unit (overlapping unit) 12, a sheet carry-out unit 13, and a bypass conveyance unit 14. The intermediate transport unit B1 can stack two sheets output from the image forming apparatus A in the stacking unit 12, and the post-processing unit is turned upside down while the two stacked sheets are stacked. It is conveyed to B2. A sheet that does not require binding processing or a sheet that does not need to be turned upside down is conveyed to the post-processing unit B2 via the bypass conveyance unit 14 without passing through the stacking unit 12.

  The post-processing unit B2 includes an entrance conveyance unit 20, a paper discharge conveyance unit 30, a connection conveyance unit 40, an insertion paper feeding unit 50, a stack unit 60, a binding processing unit ST, and a folding unit 70. In the present embodiment, the sheet S conveyed by the connection conveyance unit 40 functioning as a conveyance unit is stacked in the stack unit 60, and a binding process is performed by the binding processing unit ST. As a result, a partial booklet composed of a plurality of sheets S is produced.

  In the case of one-sided binding in which the staple in the binding process is performed on one side of the sheet bundle, the booklet is discharged to the paper discharge tray 81. Is folded in half and discharged to the discharge tray 82.

  Note that the post-processing unit B2 in the present embodiment performs a binding process on a plurality of sheets S, but forms a booklet by gluing the plurality of sheets S or performs a punching process. It may be a thing.

  [Intermediate transport unit B1] FIG. 2 is a front sectional view of the intermediate transport unit B1. As described above, the intermediate conveyance unit B1 includes the sheet carry-in unit 11, the stacking unit 12, the sheet carry-out unit 13, and the bypass conveyance unit 14.

  The sheet carry-in unit 11 includes a sheet conveyance path r <b> 11 having conveyance rollers R <b> 1 and R <b> 2 and a guide plate 111. In the sheet carry-in portion 11, the sheets S discharged from the paper discharge portion 5E of the image forming apparatus A are sequentially received and conveyed.

  The stacking unit 12 includes two guide plates 121 arranged in parallel, a vertical alignment unit including a stop member 123, a horizontal alignment member 122, a carry-in drive roller R3, a carry-out drive roller R4, and a sheet. A conveyance path r12. When the binding process is executed in the post-processing unit B2, the sheet S received from the sheet carry-in unit 11 is stored in the stacking unit 12 and discharged upward. Further, for a specific job for executing the binding process, two sheets S are stacked in the stacking unit 12 and then discharged upward in a state where the two sheets are stacked.

  The sheet carry-out unit 13 includes an intermediate conveyance roller R5, paper discharge rollers R6a, R6b, R7a, R7b, and a sheet conveyance path r13 having a guide plate 131. In the sheet carry-out unit 13, the front and back of the sheets S stored in the stacking unit 12 (in some cases, two sheets S stacked in the stacking unit 12) are reversed and conveyed to the post-processing unit B2.

  The bypass conveyance unit 14 includes a sheet conveyance path r14. The conveyance of the sheet S to the bypass conveyance unit 14 is performed when it is not necessary to convey the sheet S to the stacking unit 12. For example, there is a case where the binding process of the sheet S is unnecessary, or a case where the sheet S is discharged without being reversed.

  The conveyance path switching unit G2 arranged in the sheet carry-in unit 11 branches the sheet S to the stacking unit 12 or the bypass conveyance unit 14. On the upper part of the stacking unit 12, a conveyance path switching unit G1 is arranged. The conveyance path switching unit G <b> 1 switches between introduction of the sheet S into the stacking unit 12 and discharge of the sheet S from the stacking unit 12. The transport path switching units G1 and G2 are each connected to a solenoid and driven.

  FIG. 3 is a front sectional view showing driving means around the stacking unit 12 of the intermediate transport unit B1. The conveyance path switching unit G1 that supports the carry-in driven roller R10 and the carry-out driven roller R11 is driven and swung by the solenoid SOL1. The carry-in drive roller R3 is driven by the solenoid SOL2 and opens and closes the sheet conveyance path r11 (see FIG. 2). The vertical alignment member 124 is driven to swing by the solenoid SOL3.

  The motor M1 drives and rotates the conveying roller R2, and rotates the carry-in driving roller R3 via the belt. The motor M2 drives and rotates the carry-out driving roller R4.

  The stop member 123 is locked to the belt 125 rotated by the motor M3, and is guided up and down by the guide bar 126. The standby position at the time of preparation for receiving the stop member 123 differs depending on the length of the conveyed sheet S in the conveyance direction.

  When two sheets are stacked in the stacking unit 12, the stop member 123 is kept on standby, and the first sheet S <b> 1 is received and stopped. Then, the second sheet S <b> 2 is conveyed to the stacking unit 12, and the two sheets S <b> 1 and S <b> 2 are stacked on the stop surface portion 123 </ b> A of the stop member 123.

  The two sheets S <b> 1 and S <b> 2 received by the stacking unit 12 are aligned in the vertical and horizontal directions by the horizontal alignment member 122, the vertical alignment member 124, and the stop surface portion 123 </ b> A of the stop member 123. After the alignment, the stop member 123 is raised, and the sheets S1 and S2 stored in the stacking unit 12 are brought into pressure contact with the carry-out driving roller R4 and the carry-out driven roller R11 so that the upper ends of the stacked sheets S1 and S2 are overlapped. Pinch.

  The sheets S1 and S2 sandwiched between the carry-out driving roller R4 and the carry-out driven roller R11 by the driving rotation of the carry-out driving roller R4 are retracted from the sheet conveyance path r13 by the solenoid (not shown) driven by the vertical alignment member 124. Then, the sheet is conveyed to the section 13 and further sandwiched between the intermediate conveyance rollers R5 (see FIG. 2) and conveyed to the subsequent post-processing unit B2.

  Thus, the intermediate transport unit B1 delays the time for transporting the sheet S to the post-processing unit B2 by superimposing the two sheets S1 and S2 in the stacking unit 12 and transporting them to the post-processing unit B2. This enables the post-processing execution time in the post-processing unit B2. As a result, the productivity of sheets output from the image forming apparatus A is not reduced.

  [Post-Processing Unit B2] FIG. 4 is a front sectional view of the post-processing unit B2. The post-processing unit B2 includes an entrance conveyance path r20, a paper discharge conveyance path r30, and a connection conveyance path r40 as sheet conveyance paths.

  The sheet S transported from the intermediate transport unit B1 is transported in the entrance transport path r20 and guided to either the paper discharge transport path r30 or the connected transport path r40 by the transport path switching unit G20 depending on whether or not the binding process is performed. It is burned. The transport path switching unit G20 is operated by a solenoid (not shown).

  The entrance transport unit 20 is disposed in the entrance transport path r20, and includes transport roller pairs 21 and 22 that are driven by a motor (not shown) and rotate at the same peripheral speed. The transport roller pairs 21 and 22 sandwich and transport the sheet S in the entrance transport path r20.

  The paper discharge conveyance unit 30 is disposed in the paper discharge conveyance path r30, and includes conveyance roller pairs 31, 32, and 33 that are driven by a motor (not shown) and rotate at the same peripheral speed. The conveyance roller pairs 31, 32, and 33 nipping and conveying the sheet S conveyed to the paper discharge conveyance path r30.

  The coupled transport unit 40 is disposed in the coupled transport path r40, and includes transport roller pairs 41 and 42 that are driven by a motor (not shown) and rotate at the same peripheral speed. The pair of conveyance rollers 41 and 42 sandwich and convey the sheet S conveyed to the connection conveyance path r40.

  When the binding process is not performed on the sheet S, the sheet S received from the intermediate conveyance unit B1 to the entrance conveyance path r20 is guided to the discharge conveyance path r30 by the conveyance path switching unit G20, and The paper is sandwiched and transported between the transport roller pairs 31 and 32 and the discharge roller pair 33 and is discharged onto a discharge tray 91 outside the apparatus.

  On the other hand, when the binding process is performed on the sheet S, the sheet S received via the stacking unit 12 of the intermediate conveyance unit B1 is guided to the coupled conveyance path r40 by the conveyance path switching unit G20, and The paper is sandwiched and transported by a pair of transport rollers and transported to the binding processing unit ST.

  The two sheets S stacked in the stacking unit 12 are transported to the transport roller pair 41 in the connection transport unit 40 and received by the discharge roller pair RT, and function as a discharge roller pair RT (in this embodiment, a “roller pair”). ) Is discharged into the space above the stacker unit 60 that is inclined (that is, the discharge roller pair RT passes the two sheets S to the stacker unit 60). Then, the two sheets S move downward due to their own weight, and come into contact with the alignment plate SP and stop. In the alignment plate SP, the end of the sheet S on the upstream side in the conveyance direction is aligned.

  Reference numeral 62 denotes a pair of alignment members that are movably provided on both side surfaces of the stacker unit 60. The alignment member 62 is movable in a direction perpendicular to the sheet S conveyance direction. When the sheet discharged onto the stacker unit 60 is received, the sheet is opened wider than the width of the sheet, and when the sheet S slides down on the stacker unit 60 and stops at a predetermined position by contacting the alignment plate SP, the sheet width direction The width of the sheet bundle is aligned (aligned) by tapping the side edge. Then, when the sheet of the last page of the sheet bundle is placed on the stacker unit 60, after the alignment is performed, the staple processing unit ST performs the needle driving, and the sheet bundle is bound to produce a booklet.

  A notch is formed in a part of the sheet stacking surface of the stacker unit 60, and a plurality of discharge belts 67 wound around the drive pulley 65 and the driven pulley 66 drive a drive pulley 65 (not shown). It is driven by the driving force. A discharge claw 68 is integrally formed on a part of the discharge belt 67. When one-side binding is performed by the binding processing unit ST, the booklet that has been bound is held at the rear end by the discharge claw 68 of the discharge belt 67 and slides up on the stacking surface of the stacker unit 60 and is pushed upward obliquely. And is conveyed to the nip position of the paper discharge roller pair 33. The paper is sandwiched between the discharge roller pair 33 and discharged and stacked on the paper discharge tray 81.

  In the case of so-called saddle stitching in which the binding process by the stapler 71 is performed at the center of the sheet bundle, the booklet formed by the staple process is folded in the folding unit 80 and then discharged to the sheet discharge tray 82. Is done.

  When the binding process is continuously performed, after the sheet of the last page of the preceding sheet bundle is placed and aligned on the stacker unit 60, until the bound booklet is removed from the stacker unit 60, The sheet S constituting the subsequent sheet bundle cannot be conveyed to the stacker unit 60. When the booklet is removed from the stacker unit 60 by discharging the produced booklet, the sheets S constituting the subsequent sheet bundle can be placed on the stacker unit 60.

  [Block Diagram of Image Forming System] FIG. 5 is a block diagram of a control system in the image forming system, and only representative ones are shown here.

  A PC, which is a terminal such as a personal computer, is connected to the image forming apparatus A via a network. A CPU (Central Processing Unit) 101 controls the operation of the entire image forming apparatus A, and is connected to a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads out various control programs stored in the ROM 102, develops them in the RAM 103, and controls the operation of each unit. In addition, the CPU 101 executes various processes according to the program expanded in the RAM 103 and stores the processing results in the RAM 103. Then, the processing result stored in the RAM 103 is stored in a predetermined storage destination.

  Image data generated by the image reading unit 1 and image data transmitted from a PC connected to the image forming apparatus A are subjected to image processing by the image processing unit 2. The image writing unit 3 and the image forming unit 4 receive the image data processed by the image processing unit 2 and form an image on the sheet S1.

  The CPU 201 in the post-processing apparatus B controls the operation of the entire post-processing apparatus B in cooperation with the ROM 202 and the RAM 203, and executes a series of operations based on signals transmitted from the image forming apparatus A. The CPU 201 reads various control programs stored in the ROM 202 and develops them in the RAM 203 to control the operation of each unit. In the present embodiment, the CPU 201 functions as a “control unit” by operating in cooperation with the ROM 202 and the RAM 203.

  The CPU 201 cooperates with the ROM 202 and the RAM 203 to control the connecting and conveying unit 40, the binding processing unit ST, and the like, and executes the binding process on the sheet S.

  [Alignment of Edges of Sheet S in Binding Processing Unit ST] As described with reference to FIGS. 3 and 4, when two sheets S are stacked in the stacking unit 12, the two stacked sheets S are later. It is transported in a state of being overlapped by the connection transport unit 40 of the processing unit B2, and discharged to the space above the stacker unit 60 by the discharge roller pair RT. Thereafter, the two discharged sheets S are brought into contact with the alignment plate SP and the end portions of the sheets S are aligned.

  However, as shown in FIG. 9, when the upper sheet S1 comes into contact with the alignment plate SP before the lower sheet S2 in the two discharged sheets, the lower sheet S2 is sandwiched between the sheets. Accordingly, the movement to the alignment plate SP is restricted, and the end portion of the lower sheet S2 does not contact the alignment plate SP. If it becomes such a state, the edge part of the sheet | seat S will not align, and even if it performs binding processing by the binding process part ST, the booklet of the beautiful appearance with which the edge part aligned will not be produced.

  In view of this, among the two sheets, the discharge roller pair RT is installed on the upstream side in the sheet conveyance direction with respect to the post-processing unit including the stacker unit 60, the alignment plate SP, and the binding processing unit ST. The upper sheet precedes the lower sheet. Hereinafter, this point will be described in detail with reference to FIGS.

  FIG. 6 is an enlarged view of the discharge roller pair RT. The discharge roller pair RT includes a first roller RT1 and a second roller RT2, and the first roller RT1 and the second roller RT2 are rotated at different rotational speeds by the same or different drive motors (not shown). The first roller RT1 and the second roller RT2 are set so that the rotational speed of the first roller RT1 is higher than the rotational speed of the second roller RT2 in order to cause the upper sheet S to precede when the two sheets S are sandwiched. Yes.

A torque limiter TR is installed inside the second roller RT2, and when the discharge roller pair RT holds one sheet S as shown in FIG. 6, it follows the rotational speed of the first roller RT1. The second roller RT2 rotates and conveys the sandwiched sheet S in the direction of the arrow. Similarly, when the discharge roller pair RT does not sandwich the sheet S, the second roller RT2 rotates similarly following the rotation speed of the first roller RT1. The relationship between the sheet S and the torque limiter TR satisfies the following relational expression.
F1 <F2
F1 <F3
F1: Friction force (resistance force) of torque limiter TR
F2: Friction force between the second roller RT2 and the sheet S F3: Friction force between the first roller RT1 and the second roller RT2 The load adjustment unit CH functioning as an adjustment unit presses the first roller RT1 and the second roller RT2. The load is adjusted, and the load adjuster CH is normally urged in the direction a by the urging spring or the like with the support shaft CH1 as the rotation center. As a result, a part of the load adjusting portion CH is bonded to the shaft of the first roller RT1, and the pressure bonding load between the first roller RT1 and the second roller RT2 is increased. When the discharge roller pair RT sandwiches and conveys one sheet S, the first roller RT1 is urged in the direction of the second roller RT2 by the load adjusting unit CH to increase the pressure-bonding load, thereby strengthening the sheet S. Nipped and transported.

  FIG. 7 is an explanatory diagram illustrating a state in which two sheets are nipped and conveyed by the discharge roller pair RT.

  When the two sheets S1 and S2 are conveyed by the connecting and conveying unit 40 to the discharge roller pair RT, the upper sheet S1 contacts the first roller RT1, and the lower sheet S2 contacts the second roller RT2. To do. Since the rotation speed of the first roller RT1 is higher than the rotation speed of the second roller RT2, the upper sheet S1 and the lower sheet S2 are conveyed to the discharge roller pair RT in any positional relationship as shown in FIG. Thus, the upper sheet S1 precedes the lower sheet S2 (the preceding amount t of the upper sheet S1 with respect to the lower sheet S2 is preferably about 5 mm). As a result, when the upper sheet S1 and the lower sheet S2 are discharged by the discharge roller pair RT, as shown in FIG. 10, the lower sheet S2 contacts the alignment plate SP before the upper sheet S1. Get in touch. Even if the lower sheet S2 comes into contact with the aligning plate SP first by the upper sheet S1, the upper sheet S1 is not sandwiched between the sheets, and therefore moves toward the aligning plate SP by its own weight. Abut. Therefore, even if two sheets are discharged by the discharge roller pair RT, the end portions of the two sheets are reliably aligned by the alignment plate SP.

  As shown in FIG. 7, in order for the upper sheet S1 to precede the lower sheet S2 in the discharge roller pair RT, the pressure-bonding load in the discharge roller pair RT is reduced to reduce the upper sheet S1 and the lower sheet S2. The sheet S2 needs to be shifted. Therefore, the load adjusting unit CH is rotated in the b direction, and the load adjusting unit CH is separated from the shaft of the first roller RT1, thereby reducing the pressure bonding load. The rotation of the load adjusting unit CH in the b direction is performed by bringing a cam into contact with a part of the load adjusting unit CH, for example.

  The operation of the load adjusting unit CH is controlled by the CPU 201 or the like in the post-processing apparatus B. When the discharge roller pair RT discharges (passes) two sheets toward the binding processing unit ST, the load adjusting unit CH uses the load adjusting unit CH. When the pressure-bonding load is decreased and the discharge roller pair RT discharges one sheet toward the binding processing unit ST, the pressure adjustment load is increased by setting the load adjusting unit CH to the normal position. This operation is controlled by grasping the number of conveyed sheets with reference to job attribute information.

Further, in order to carry the upper sheet S1 ahead of the lower sheet S2, it is necessary to satisfy the following relational expression. In order to satisfy the following relational expression, the material of the surfaces of the first roller RT1 and the second roller RT2 and the structure of the torque limiter TR are adjusted.
F4 <F5
F4 <F6
F4 <F7
F4: Friction force between upper sheet S1 and lower sheet S2 F5: Friction force between first roller RT1 and upper sheet S1 F6: Friction force between second roller RT2 and lower sheet S2 F7: Torque Friction force (resistance force) of limiter TR
As described above with reference to FIGS. 6 and 7, the upper sheet S1 is preceded by the lower sheet S2 by the discharge roller pair RT, and the two sheets are processed by the post-processing unit (stacker unit 60, alignment plate). SP and the binding processing unit ST) can perform post-processing such as good binding processing because the end of the sheet is neatly aligned with the alignment plate SP even if two sheets are stacked and conveyed. I can do it.

  Further, a place where two sheets are overlapped (in this embodiment, the stacking unit 12 in the intermediate transport unit B1) and the discharge roller pair RT are provided separately, and a post-processing unit (stacker unit 60, alignment plate SP, and binding processing unit ST). ), The discharge roller pair RT is installed immediately before the upstream side in the sheet conveyance direction, so that the end of the sheet S is finally aligned regardless of the position where the two sheets are stacked in the image forming system. It can be neatly arranged with the board SP. Accordingly, it is possible to freely set the configuration of the image forming system, such as connecting another unit between the intermediate transport unit B1 and the post-processing unit B2.

  Further, since the torque limiter TR is installed on the second roller RT2, the second roller RT2 is attached to the first roller RT1 when one sheet is sandwiched between the discharge roller pair RT or when the sheet is not sandwiched. When the two sheets are sandwiched between the discharge roller pair RT, the second roller RT2 does not follow the first roller RT1. Therefore, when two sheets are sandwiched by a simple configuration, the upper sheet can be preceded by the lower sheet.

  In addition, this invention is not limited to the said embodiment, Even if there exists a change and addition in the range which does not deviate from the summary of this invention, it is contained in this invention.

  In the image forming system shown in FIG. 1, the image forming apparatus A and the post-processing apparatus B are independent casings, but the image forming apparatus A and the post-processing apparatus B may be the same casing.

  In the present embodiment, the torque limiter TR is installed on the second roller RT2, but the torque limiter TR may be installed on the first roller RT1.

1 is an overall configuration diagram of an image forming system including a large-capacity paper feeding device, an image forming device, and a post-processing device. It is front sectional drawing of an intermediate conveyance unit. It is front sectional drawing which shows the drive means in the stacking part periphery of an intermediate conveyance unit. It is front sectional drawing of a post-processing unit. 2 is a block diagram of a control system in the image forming system. FIG. It is an enlarged view of a discharge roller pair. It is explanatory drawing which shows the state which clamps and conveys two sheets by a discharge roller pair. It is explanatory drawing which shows the outline of the general post-processing part which performs a binding process. It is an enlarged view around a matching plate. It is an enlarged view around a matching plate.

Explanation of symbols

A image forming apparatus B post-processing apparatus B1 intermediate transport unit B2 post-processing unit CH load adjusting unit LT large-capacity sheet feeding device RT discharge roller pair RT1 first roller RT2 second roller ST binding processing unit TR torque limiter 60 stacker unit 70 folding Portion 81 Discharge tray 82 Discharge tray 101, 201 CPU
102, 202 ROM
103, 203 RAM

Claims (9)

A transport unit for transporting two stacked sheets;
A post-processing unit that performs post-processing on a sheet conveyed by the conveyance unit;
A pair of rollers that receive the two sheets conveyed by the conveyance unit, and precede the upper sheet of the two sheets to pass the two sheets to the post-processing unit;
A post-processing apparatus comprising: The post-processing apparatus according to claim 1, wherein the roller pair is installed immediately upstream of the post-processing unit on the upstream side in the sheet conveyance direction. The post-processing apparatus according to claim 1, wherein the post-processing unit performs post-processing by aligning an end of the sheet on the upstream side in the conveyance direction. A first roller that constitutes the roller pair and contacts an upper sheet of the two sheets;
A second roller that constitutes the roller pair and contacts a lower sheet of the two sheets;
The post-processing apparatus according to any one of claims 1 to 3, wherein a rotation speed of the first roller is higher than a rotation speed of the second roller. The post-processing apparatus according to claim 4, wherein a torque limiter is installed on one of the first roller and the second roller. An adjusting unit for adjusting a pressure-bonding load between the first roller and the second roller;
When the roller pair passes the two sheets to the post-processing unit, the adjustment load is reduced by the adjusting unit, and when the roller pair passes one sheet to the post-processing unit, the adjustment is performed. A control unit for controlling the adjusting unit so as to increase the pressure-bonding load by the unit;
The post-processing apparatus according to claim 4 or 5, comprising: The post-processing apparatus according to any one of claims 1 to 6, further comprising an overlapping portion that overlaps two sheets. The post-processing apparatus according to claim 1, wherein the post-processing unit performs a binding process on a sheet conveyed by the conveyance unit. An image forming system comprising: the post-processing apparatus according to claim 1; and an image forming apparatus that forms an image on a sheet.

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