Sheet processing device for processing plurality of sheets

Abstract

This sheet processing device comprises a processing means configured to sequentially receive and load each sheet of a plurality of sheets and perform processing on the loaded plurality of sheets, and a control means configured to control the conveyance of the plurality of sheets. The control means is further configured to stop the conveyance of a first sheet on the upstream side of the processing means in the sheet conveyance direction when, during the processing by the processing means, the first sheet conveyed to the sheet processing device is determined not to be an object of the processing, but must nevertheless be conveyed toward the processing means.

Description

Sheet processing apparatus for processing multiple sheets

[0001] The present disclosure relates to a sheet processing apparatus that processes a plurality of sheets.

[0002] 2. Description of the Related Art Image forming systems are in use, each of which includes an image forming apparatus that forms an image on a sheet, and a sheet processing apparatus that performs processes such as gluing and stapling on a plurality of sheets on which the image has been formed by the image forming apparatus.

[0003] Japanese Patent Application Laid-Open No. 2006-129999 discloses a configuration for preventing the waste of sheets that can be used as deliverables among sheets that have already been conveyed into an image forming apparatus when a jam occurs. Specifically, Japanese Patent Application Laid-Open No. 2006-129999 discloses that, when a jam occurs, sheets that can be used as deliverables among sheets that are upstream of the jammed sheet are discharged to a different destination.

[0004] JP 2015-13430 A

[0005] Misprints can occur in image forming systems. For example, a misprint can occur when a sheet of a different size than the sheet to be used as the final product is mistakenly fed into the image forming device. Alternatively, a misprint can occur when a low-quality image is formed on a sheet due to poor sheet transport or the like.

[0006] When performing a process such as gluing on multiple sheets, the sheets to be processed are conveyed sequentially to a sheet processing apparatus and stacked as a sheet bundle within the sheet processing apparatus. The sheet processing apparatus then performs a predetermined process on the stacked sheet bundle. If a misprint occurs while stacking multiple sheets for processing, the misprinted sheet ends up being stacked on top of the preceding sheet bundle. Because the misprinted sheet is a sheet that should not be processed, the user must remove the misprinted sheet from the stacked sheets. However, in this case, there is a possibility that the user will remove a sheet other than the misprinted sheet. Furthermore, when processing a sheet bundle, a sheet bundle alignment process is usually performed, but there is a possibility that the alignment of the sheet bundle will be disrupted when the user removes the misprinted sheet.

[0007] Therefore, when a misprint occurs, it is desirable to dynamically change the discharge destination of the misprinted sheet so that the misprinted sheet is not stacked on top of the preceding sheet stack. However, depending on the timing at which the misprint is detected, it may already be impossible to change the discharge destination.

[0008] According to one aspect of the present disclosure, a sheet processing device includes a processing means configured to receive and stack each of a plurality of sheets in sequence and process the stacked sheets, and a control means configured to control the transport of the plurality of sheets, and the control means is further configured to stop the transport of the first sheet upstream of the processing means in the sheet transport direction when the control means determines that a first sheet transported to the sheet processing device is not subject to the processing when performing the processing by the processing means, but the first sheet must be transported toward the processing means.

[0009] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals.

[0010] The accompanying drawings, which are incorporated into and constitute a part of the specification, illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.

[0014] Figure 1 illustrates an example of a schematic configuration of an image forming system according to some embodiments.

[0015] Figure 2 illustrates an example of an adhesive image according to some embodiments.

[0016] Figure 3 illustrates another example of an adhesive image according to some embodiments.

[0017] Figure 4 illustrates an alignment process according to some embodiments.

[0018] Figure 5 illustrates an alignment process according to some embodiments.

[0019] Figure 6 illustrates an alignment process according to some embodiments.

[0020] Figure 7 illustrates an example of a hardware configuration of an image forming system according to some embodiments.

[0021] Figure 8 illustrates a functional block diagram of a finisher control unit according to some embodiments.

[0022] Figure 9 illustrates a transport destination determination process according to some embodiments.

[0023] Figure 10 illustrates a transport destination determination process according to some embodiments.

[0024] Figure 11 illustrates a flowchart of processing performed by a finisher control unit according to one embodiment. 1A-1C are diagrams showing example screens displayed for sheet removal according to some embodiments, 1B-1C are diagrams showing example screens displayed for sheet removal according to some embodiments, 1C-1C are diagrams showing example screens displayed for sheet removal according to some embodiments, 1D ...

[0011] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the claims. Although multiple features are described in the embodiments, not all of these multiple features are required, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] First Embodiment FIG. 1 shows a schematic configuration of an image forming system according to this embodiment. The image forming system includes an image forming apparatus 1 and a sheet processing apparatus 300. In the following description, the sheet processing apparatus 300 will be simply referred to as the "processing apparatus 300." The image forming apparatus 1 includes four image forming units 7k, 7y, 7m, and 7c. The image forming units 7k, 7y, 7m, and 7c contain black, yellow, magenta, and cyan toner, respectively, and form black, yellow, magenta, and cyan toner images on the intermediate transfer belt 3. In this embodiment, black toner is also used as a powder adhesive in the adhesion process in the processing apparatus 300. In other words, if the image formed on a sheet for adhering sheets together is referred to as an adhesion image and the other images are referred to as user images, in this embodiment, black toner is used for both the adhesion image and the user image, and the other color toners are used only for the user image. Note that the toner used for the adhesion image may be a toner of a color other than black.

[0013] The image forming units 7k, 7y, 7m, and 7c have the same configuration except for the color of the toner used. Therefore, the following description will focus on the configuration of image forming unit 7k. During image formation, the photoconductor 73 rotates clockwise in the drawing. The charging roller 71 charges the surface of the photoconductor 73 to a uniform potential. The exposure unit 2 exposes the photoconductor 73 to light to form an electrostatic latent image on the photoconductor 73. The development unit 72 develops the electrostatic latent image formed on the photoconductor 73 with toner to form a toner image on the photoconductor 73. The primary transfer roller 74 outputs a primary transfer voltage to transfer the toner image on the photoconductor 73 to the intermediate transfer belt 3. The toner images formed on the photoconductors 73 of the image forming units 7k, 7y, 7m, and 7c are superimposed and transferred to the intermediate transfer belt 3, thereby reproducing colors different from black, yellow, magenta, and cyan.

[0014] The secondary transfer roller 5 outputs a secondary transfer voltage to transfer the toner image on the intermediate transfer belt 3 to the sheet S transported from the cassette 8 or the tray 20. The timing at which the registration roller 9 transports the sheet S to the position opposite the secondary transfer roller 5 is determined based on the timing at which the registration sensor 37 detects the sheet S. The fixing unit 6 fixes the toner image to the sheet S by applying heat and pressure to the sheet S on which the toner image has been transferred. When an image is formed on only one side (first side) of the sheet S, the sheet S on which the toner image has been fixed is guided by a guide 33 to a conveyance path provided with rollers 34. The rollers 34 then convey the sheet S to the processing device 300.

[0015] When forming images on both sides of the sheet S, the sheet S, on which the toner image has been fixed on its first side, is guided by a guide 33 to a conveying path provided with rollers 35. The rollers 35 reverse their rotation direction when the trailing edge of the sheet S reaches the rollers 35. Thus, the sheet S is conveyed again to a position facing the secondary transfer roller 5 via a double-sided conveying path 36, and the toner image is transferred onto its second side. The toner image formed on the second side of the sheet is fixed by a fixing unit 6. The sheet S is then guided by a guide 33 to a conveying path provided with rollers 34, and conveyed to the processing device 300.

[0016] The guide 22 of the processing device 300 is set to either a processing state or a non-processing state. In the processing state (first state), the guide 22 guides the sheet S to a conveying path provided with rollers 21. In the non-processing state (second state), the guide 22 guides the sheet S to a conveying path provided with rollers 23. The rollers 23 discharge and place the sheet S on the lower tray 303. The rollers 21 convey the sheet S downstream, and the rollers 29 convey the sheet S conveyed by the rollers 21 to the processing device 42. The processing device 42 receives and stacks the conveyed sheets in order, and performs alignment and bonding processes (described later) on the stacked multiple sheets S. The processing device 42 discharges a booklet created by performing the alignment and bonding processes onto the upper tray 302 as a product.

[0017] An inlet sensor 27 that detects the sheet S is provided upstream of the guide 22 in the conveying direction of the sheet S. The inlet sensor 27 detects whether the sheet S is present at the detection position. In this embodiment, it is assumed that the state of the guide 22 needs to be changed before the inlet sensor 27 detects the leading edge of the sheet S. More specifically, when the guide 22 is set to the processing state, the guide 22 can be changed to the non-processing state and the sheet S can be discharged to the lower tray 303 until the leading edge of the sheet S is detected by the inlet sensor 27. On the other hand, when the guide 22 is set to the processing state, after the leading edge of the sheet S is detected by the inlet sensor 27, the sheet S must be conveyed toward the processing section 42. The same applies when the guide 22 is set to the non-processing state.

[0018] Furthermore, in the processing device 300, a pre-processing sensor 50 is provided between the roller 21 and the roller 29. Also, a door 24 for a user to remove the sheet S from the conveying path is provided on the housing of the processing device 300 facing a predetermined section of the conveying path between the roller 21 and the roller 29. Note that a door sensor 25 detects whether the door 24 is open or closed.

[0019] 2A and 2B show examples of the adhesive image Tk. As shown in Fig. 2A, by forming the adhesive image Tk on the end of the long side of the sheet S, a long-length booklet can be produced by the adhesive process using the processing device 300. Also, as shown in Fig. 2B, by forming the adhesive image Tk on a part of the end of the long side of the sheet S, a corner-stitched booklet can be produced by the adhesive process using the processing device 300.

[0020] 3A to 3D are explanatory diagrams of the alignment process by the processing section 42. As shown in FIG. 3A, the roller 29 transports the sheet S to the processing section 42. As shown in FIG. 3B, the half-moon roller 40 performs vertical alignment by pushing the sheet S transported to the processing section 42 toward the vertical alignment reference plate 39. Note that the conveying pressure of the half-moon roller 40 is adjusted so that the sheet S slips after it contacts the vertical alignment reference plate 39. As shown in FIG. 3C, after the vertical alignment process is completed, the horizontal alignment jogger 41 moves the sheet S until it abuts against the horizontal alignment reference plate 500 (dotted line), thereby performing horizontal alignment. FIG. 3D shows the state after the alignment process is completed.

[0021] A plurality of sheets to be bonded are transported in order and stacked in the processing section 42. The alignment process is performed each time a sheet S is transported to the processing section 42. Furthermore, each time a predetermined number of sheets S are added to the processing section 42, the processing section 42 performs a bonding process, which will be described later, using the thermocompression bonding unit 51. In the following description, the predetermined number is assumed to be five sheets, as an example. Therefore, when 15 sheets S are bonded together to form one booklet, the bonding process is performed three times to create one booklet. Furthermore, when 18 sheets S are bonded together to form one booklet, the bonding process is performed four times to create one booklet.

[0022] 4A and 4B are views of the processing section 42 viewed in the direction in which the sheet S is conveyed by the rollers 29. A ceramic heater 501, which has a built-in heating element, is supported by a resin heater support 503 and heats an aluminum heating plate 502. The temperature of the ceramic heater 501 is controlled based on a temperature detected by a temperature sensor (not shown). The heating plate 502 also has a pressure applying section A. A pressure applying lever 504 presses the heater support 503, the ceramic heater 501, and the heating plate 502 downward in FIG. 4 , i.e., toward the stacked sheet S, via a rigid metal stay 505. As a result, the sheet S stacked in the processing section 42 is heated and pressurized by the heating plate 502. A pressure applying plate 506 is provided on the opposite side of the sheet S from the heating plate 502 to receive the pressure applied by the heating plate 502. The pressure applying plate 506 is made of, for example, silicone rubber.

[0023] FIG. 4A shows a state in which five sheets S1-1 to S1-5 are stacked in the processing section 42. As shown in FIG. 4A, an adhesive image Tk is formed in an area that is heated and pressed by the heating plate 502. In the state shown in FIG. 4A, the adhesive image Tk is melted and an adhesive process is performed by heating and pressing the five sheets S with the heating plate 502. FIG. 4B shows a state in which five new sheets S2-1 to S2-5 are stacked on top of the sheets S1-1 to S1-5 that have already been subjected to the adhesive process. In the state shown in FIG. 4B, ten sheets S are adhered together by heating and pressing the stacked sheets S with the heating plate 502.

[0024] 5 shows an example of a schematic hardware configuration of the image forming system. The image forming apparatus 1 has a printer control unit 100, and the processing device 300 has a finisher control unit 400. The printer control unit 100 and the finisher control unit 400 are connected to each other and cooperate to control the operation of the image forming system.

[0025] The printer control unit 100 includes a central processing unit (CPU) 101 and a memory 102. The CPU 101 reads and executes programs stored in the memory 102 to provide overall control of the image forming apparatus 1. For example, the CPU 101 causes the printer unit 1e to perform an image formation operation. The printer unit 1e is a collective term for the components of the image forming apparatus 1 shown in FIG. 1. The memory 102 includes a non-volatile storage medium such as a read-only memory (ROM) and a volatile storage medium such as a random access memory (RAM), and serves as a storage location for programs and data, as well as a workspace for the CPU 101 to execute the programs. The memory 102 is an example of a non-transitory computer-readable storage medium that stores programs for controlling the image forming apparatus.

[0026] The printer control unit 100 is connected to external devices such as personal computers and portable information devices via an external interface (I / F) 104, and receives commands to execute print jobs for the image forming system. The printer control unit 100 is also connected to an operation display unit 103, which is a user interface for the image forming system. The operation display unit 103 includes a display device such as a liquid crystal panel that presents information to the user, and an input device such as physical buttons and a touch panel function unit of the liquid crystal panel that accepts input operations by the user. The printer control unit 100 communicates with the operation display unit 103 to control the display content of the display device and receive information input via the input device.

[0027] The finisher control unit 400 has a central processing unit (CPU) 401, a memory 402, and an I / O port 403. The CPU 401 reads and executes programs stored in the memory 402 to provide overall control of the processing device 300. The memory 402 includes a non-volatile storage medium such as a read-only memory (ROM) and a volatile storage medium such as a random access memory (RAM), and serves as a storage location for programs and data as well as a workspace for the CPU 401 when executing the programs. The memory 402 is an example of a non-transitory computer-readable storage medium that stores programs for controlling the processing device 300. The CPU 401 and memory 402 are connected to the I / O port 403 via a bus 404, and the I / O port 403 inputs and outputs control signals to and from various components of the processing device 300.

[0028] The functions of the printer control unit 100 and the finisher control unit 400 may be implemented in hardware using an application-specific integrated circuit (ASIC) or the like. Alternatively, the functions of the printer control unit 100 and the finisher control unit 400 may be implemented in software, such as by a program executed by one or more processors. Alternatively, the functions of the printer control unit 100 and the finisher control unit 400 may be implemented by a combination of hardware and software. Furthermore, the printer control unit 100 may be configured to perform some or all of the functions of the finisher control unit 400 described below.

[0029] The I / O port 403 is connected to motors M1 to M6, the entrance sensor 27, the pre-processing sensor 50, the door sensor 25, the ceramic heater 501, and the solenoid 221. The motors M1 to M6 are the drive sources for the rollers 21, 23, 29, the half-moon roller 40, the lateral alignment jogger 41, and the pressure lever 504, and the solenoid 221 is the drive source for the guide 22.

[0030] FIG. 6 shows functional blocks realized by the CPU 401 of the finisher control unit 400 executing a program stored in the memory 402. Note that FIG. 6 shows only functional blocks necessary for explaining the embodiment, and omits functional blocks not necessary for explaining the embodiment. The transport control unit 421 controls the transport of the sheet S, i.e., performs the transport process of the sheet S. The transport process of the sheet S includes a process of switching the destination of the sheet S by driving the guide 22 via the solenoid 221. The removal sheet determination unit 422 determines the sheet to be removed, which will be described later. The destination determination unit 423 determines the destination of the sheet to be removed, etc. The notification unit 424 performs a process of presenting an instruction to the user to remove the sheet S whose transport has been stopped inside the processing device 300. The sheet length detection unit 425 detects the sheet length, which is the length of the sheet S in the transport direction. The information receiving unit 426 receives misprint information, which will be described later, from the image forming apparatus 1.

[0031] Next, misprints will be described. A misprint refers to an image formation defect that occurs when the size of the sheet S fed to the image forming apparatus 1 is different from the size of the sheet S on which an image is to be formed, or when the timing of conveying the sheet S is off. The printer control unit 100 of the image forming apparatus 1 can detect the sheet length using the registration sensor 37. The printer control unit 100 detects the occurrence of a misprint when the size of the fed sheet S is not within the allowable range for the size specified in the print job. When the printer control unit 100 detects the occurrence of a misprint, it notifies the information receiving unit 426 of misprint information indicating the occurrence of the misprint and the sheet S on which the misprint occurred. In this embodiment, the misprinted sheet S is referred to as a removal target sheet M. Therefore, in this embodiment, the removal sheet determination unit 422 determines the removal target sheet M based on the misprint information.

[0032] The destination determination unit 423 determines the destination of the removal target sheet M. The process performed by the destination determination unit 423 will be described below with reference to FIGS. 7A to 9B. FIG. 7A illustrates an example of the state at the time when the information receiving unit 426 receives misprint information. According to FIG. 7A, multiple sheets S on which images were formed before the removal target sheet M are stacked as a sheet bundle S' in the processing unit 42. The leading edge of the removal target sheet M has not yet reached the detection position of the entrance sensor 27. In the case of FIG. 7A, the state of the guide 22 can be changed from the processing state to the non-processing state, and the removal target sheet M can be conveyed to the lower tray 303. Therefore, if the entrance sensor 27 has not detected the leading edge of the removal target sheet M at the time when the misprint is notified, the destination determination unit 423 determines that the removal target sheet M should be discharged to the lower tray 303. This prevents the removal target sheet M, which is not subject to processing by the processing unit 42, from being stacked on top of the sheet bundle S', as shown in FIG. 7B. Therefore, after printing is resumed, the sheets S to be processed in the processing section 42 are stacked in order on the sheet stack S' to create a booklet.

[0033] The states shown in Figures 7A and 7B can occur, for example, when an A4-size (sheet length: 297 mm) sheet is to be processed and an A5-size (sheet length: 210 mm) sheet, which is shorter than the sheet to be processed, is mistakenly fed to the image forming device 1.

[0034] FIG. 8A shows another example of the state at the timing when the information receiving unit 426 receives misprint information. In FIG. 8A , multiple sheets S on which images were formed before the removal target sheet M are stacked as a sheet bundle S' in the processing unit 42. The leading edge of the removal target sheet M has already reached the detection position of the entrance sensor 27. In the case of FIG. 8A , the removal target sheet M cannot be conveyed to the lower tray 303. In this case, the conveyance destination determination unit 423 conveys the removal target sheet M toward the processing unit 42, but determines that the conveyance of the removal target sheet M should be stopped at a predetermined removal position. FIG. 8B shows a state in which the conveyance of the removal target sheet M is stopped at the removal position. The removal position is a position within a predetermined range where the user can remove the removal target sheet M from the inside of the processing device 300 by opening the door 24 (open state). This prevents the removal target sheet M from being stacked on top of the sheet bundle S', as shown in FIG. 8B . Therefore, after printing is resumed, the sheets S to be processed in the processing section 42 are stacked in order on the sheet stack S' to create a booklet.

[0035] The states shown in Figures 8A and 8B can occur, for example, when an A4-size (sheet length: 297 mm) sheet is to be processed and a legal-size (sheet length: 355.6 mm) sheet, which is longer than the sheet to be processed, is mistakenly fed to the image forming device 1.

[0036] FIG. 9A shows another example of the state at the timing when the information receiving unit 426 receives the misprint information. The difference from the example of FIG. 8A is that there is no sheet S on which an image has been formed before the removal target sheet M, and therefore no sheet stack S' is stacked in the processing unit 42. In the case of FIG. 9A , since there is no preceding sheet stack S', the removal target sheet M can be conveyed directly to the processing unit 42. Therefore, if there is no preceding sheet stack S', the conveyance destination determination unit 423 determines to convey the removal target sheet M to the processing unit 42 or to discharge the removal target sheet M to the upper tray 302 via the processing unit 42. FIG. 9B shows the state after the removal target sheet M has been conveyed to the processing unit 42. Note that if there is no preceding sheet stack S', the removal target sheet M can also be conveyed to the processing unit 42 instead of the lower tray 303, even if the inlet sensor 27 has not detected the leading edge of the sheet S at the timing when the information receiving unit 426 receives the misprint information.

[0037] FIG. 10 is a flowchart of the process performed by the finisher control unit 400. In S10, the finisher control unit 400 waits until the information receiving unit 426 receives print information from the printer control unit 100. When the information receiving unit 426 receives the print information from the printer control unit 100, the removal sheet determination unit 422 determines the removal target sheet M based on the print information. In S11, the transport destination determination unit 423 determines whether a preceding sheet stack S' is present in the processing unit 42. If no sheet stack S' is present, the transport destination determination unit 423 determines that the removal target sheet M should be transported to the upper tray 302 via the processing unit 42. In this case, in S16, the transport control unit 421 transports the removal target sheet M to the upper tray 302 via the processing unit 42. Note that if the user can remove sheets stacked in the processing unit 42, the removal target sheet M may be transported to the processing unit 42 instead of the upper tray 302.

[0038] If a sheet stack S' is present, the transport destination determination unit 423 determines in S12 whether the removal target sheets M can be discharged to the lower tray 303. As described above, in this embodiment, if the entrance sensor 27 does not detect the leading edge of the removal target sheets M, the transport destination determination unit 423 determines that the removal target sheets M can be discharged to the lower tray 303. In this case, the transport control unit 421 changes the state of the guide 22 in S13 to discharge the removal target sheets M to the lower tray 303.

[0039] On the other hand, if the removal target sheet M cannot be discharged to the lower tray 303, the transport destination determination unit 423 transports the removal target sheet M toward the transport unit 42, but determines that the transport should stop at the removal position. In this case, in S14, the transport control unit 421 controls the transport of the removal target sheet M so that the removal target sheet M stops at the removal position. In addition, in S15, the notification unit 424 causes the printer control unit 100 to remove the removal target sheet M and to perform processing to notify the user of the procedure.

[0040] 11A to 11C show an example of a procedure for removing the sheet M to be removed, which is displayed on the operation display unit 103. FIG. 11A shows that the door 24 is opened. FIG. 11B shows that the sheet M to be removed is removed, which is displayed after the door sensor 25 detects that the door 24 has been opened. The black circle in FIGS. 11A and 11B indicates the approximate position of the sheet M to be removed. FIG. 11C shows that the door 24 is closed after the sheet M to be removed. When the door sensor 25 detects that the door 24 has been closed, the notification unit 424 ends the notification process of S15.

[0041] As described above, according to this embodiment, when a removal target sheet M is conveyed to the processing device 300 while the guide 22 is set to a processing state for processing in the processing section 42, the processing device 300 controls the processing device 300 so that the removal target sheet M is not stacked on top of any sheets already stacked in the processing section 42. Specifically, the processing device 300 is configured to allow removal of the sheet S upstream of the processing section 42. If the removal target sheet M must be conveyed toward the processing section 42, the conveyance of the removal target sheet M is stopped at a position upstream of the processing section 42 where the sheet S can be removed. If the removal target sheet M can be guided to a destination other than the processing section 42 when it is determined to be a removal target sheet M, the removal target sheet M can be discharged to that destination. This configuration eliminates the need for the user to remove sheets not to be processed from the multiple sheets stacked in the processing section 42. This prevents the user from removing the wrong sheet or from disturbing the alignment of the multiple sheets stacked in the processing section 42. The processing device 300 of this embodiment is configured to allow the sheet S to be discharged by the guide 22 without passing through the processing section 42. However, the present invention can also be applied to a processing apparatus 300 in which all of the conveyed sheets S must be conveyed toward the processing section 42 .

[0042] 10 , if there is no sheet bundle S' in S11, the removal target sheet M is discharged to the upper tray 302 even if it can be discharged to the lower tray 303. However, if the removal target sheet M can be discharged to the lower tray 303, the removal target sheet M can be discharged to the lower tray 303 even if there is no preceding sheet bundle S' in the processing section 42. Furthermore, in the flowchart of FIG. 10 , the transport of the removal target sheet M is stopped at the removal position only if the removal target sheet M cannot be discharged to the lower tray 303 and there is a preceding sheet bundle S' in the processing section 42. However, if the removal target sheet M cannot be discharged to the lower tray 303, the transport of the removal target sheet M can be stopped at the removal position even if there is no preceding sheet bundle S' in the processing section 42.

[0043] Furthermore, in this embodiment, the removal target sheet M is a sheet whose sheet length is different from the sheet length of the sheet on which an image is to be formed. However, since a defect in the sheet transport control can reduce the quality of the image formed on the sheet, such a sheet can also be designated as the removal target sheet M. Note that a defect in the sheet transport control can be determined based on the timing at which a sensor (not shown) installed along the transport path of the image forming system detects the sheet. In other words, the removal target sheet M in this embodiment can be a sheet that is determined not to be used for processing in the processing unit 42 based on a predetermined criterion.

[0044] In addition, in this embodiment, the processing section 42 performs alignment processing and adhesive processing, but instead of adhesive processing, it may perform stapling or punching processing. More generally, this embodiment is applicable to a processing apparatus that stacks multiple sheets in order and includes a processing section 42 that performs some kind of processing on the stacked sheets.

[0045] Second Embodiment Next, the second embodiment will be described, focusing on the differences from the first embodiment. In the first embodiment, the image forming apparatus 1 detects the occurrence of a misprint, and the processing device 300 detects the occurrence of a misprint by receiving misprint information. In this embodiment, the sheet length detection unit 425 detects the misprint. The sheet length detection unit 425 detects the sheet length of the sheet S based on the time the inlet sensor 27 has detected the sheet S and the conveyance speed of the sheet S.

[0046] For example, the image forming apparatus 1 may be configured to determine a misprint when the difference between the measured sheet length and the sheet length of the sheet on which the image is to be formed exceeds 10 mm. In other words, the image forming apparatus 1 may be configured to tolerate a difference of up to 10 mm. On the other hand, the processing apparatus 300 may be configured to tolerate a difference of up to 5 mm to maintain the accuracy of the booklet to be produced. When the image forming system is configured in this manner, it is possible that only the processing apparatus 300 may detect a misprint. As an example, if the sheet on which the image is to be formed is A4 size (sheet length: 297 mm) and a sheet with a sheet length of 305 mm is fed, the image forming apparatus 1 will not detect a misprint, but the processing apparatus 300 will.

[0047] FIG. 12 is a flowchart of the process performed by the finisher control unit 400 in this embodiment. Note that the same step numbers are assigned to process steps similar to those in the flowchart of the first embodiment shown in FIG. 10 , and their description will be omitted. In S20, the finisher control unit 400 waits until the sheet length detection unit 425 detects a misprint. The sheet length detection unit 425 detects a misprint when it detects that the detected print length of the sheet S exceeds the allowable range, even if detection of the print length of the sheet S has not been completed. For example, if the sheet length of the target sheet to be processed in the processing unit 42 is 297 mm and the allowable range is ±5 mm, the sheet length detection unit 425 detects a misprint when the detected sheet length of the sheet S exceeds 302 mm, even if detection of the print length of the sheet S has not been completed.

[0048] In this embodiment, at the timing when the misprint is detected, the leading edge of the removal target sheet M has reached the detection position of the inlet sensor 27. Therefore, in this embodiment, the removal target sheet M cannot be discharged to the lower tray 303, and therefore S12 and S13 of Fig. 10 are omitted from the flowchart. In other words, if there is no sheet stack S' in S11, the removal target sheet M is transported to the upper tray 302 via the processing unit 42. On the other hand, if there is a sheet stack S' in S11, the removal target sheet M is transported to the removal position in S14, and a notification process is performed in S15 to remove the removal target sheet M.

[0049] As described above, according to this embodiment, even if a sheet that is not a processing target occurs when processing is performed in the processing unit 42, it is possible to prevent the sheet from being stacked on top of another processing target sheet that has already been transported to the processing unit 42. Note that this embodiment can be combined with the first embodiment.

[0050] The present disclosure can also be realized by a process in which a program that realizes one or more functions of the above-described embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present disclosure can also be realized by a circuit (e.g., an ASIC) that realizes one or more functions.

[0051] The technical ideas derived from this disclosure are not limited to the disclosed exemplary embodiments, but are intended to encompass various modifications to the exemplary embodiments, or the replacement of equivalent structures or functions, etc. The scope of the following claims should be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

[0052] This application claims priority based on Japanese Patent Application No. 2024-089241, filed May 31, 2024, the entire contents of which are incorporated herein by reference.

Claims

1. A sheet processing apparatus comprising: processing means configured to receive and stack each of a plurality of sheets in order and process the stacked sheets; and control means configured to control the transport of the plurality of sheets, wherein the control means is further configured to stop the transport of the first sheet upstream of the processing means in the sheet transport direction when the control means determines that a first sheet transported to the sheet processing apparatus is not subject to the processing during the processing by the processing means but the first sheet must be transported toward the processing means.

2. The sheet processing device according to claim 1, wherein the control means is further configured to transport the first sheet to the processing means when the first sheet must be transported toward the processing means but a sheet preceding the first sheet is not loaded on the processing means.

3. A sheet processing device as described in claim 1 or 2, further comprising: a tray configured to place a sheet; and a guide configured to transport a sheet transported to the sheet processing device toward the processing means in a first state, and to transport a sheet transported to the sheet processing device toward the tray in a second state, wherein the control means is further configured to determine that the first sheet must be transported toward the processing means if it is not possible to change the state of the guide to the second state and transport the first sheet to the tray from the time it is determined that the first sheet is not a target for processing.

4. The sheet processing apparatus according to claim 3, wherein the control means is further configured to change the state of the guide to transport the first sheet to the tray if the state of the guide can be changed based on the timing to transport the first sheet to the tray.

5. The sheet processing device according to claim 4, wherein the control means is further configured to, when a sheet preceding the first sheet is not loaded on the processing means, convey the first sheet to the processing means regardless of whether the state of the guide can be changed based on the timing to convey the first sheet to the tray.

6. A sheet processing device according to any one of claims 3 to 5, further comprising a sensor that detects the sheet upstream of the guide in the transport direction, and wherein the control means is further configured to, if the sensor has already detected the first sheet at the timing, change the state of the guide and determine that the first sheet cannot be transported to the tray.

7. A sheet processing apparatus according to any one of claims 1 to 6, wherein the sheet processing apparatus is configured to allow a user to remove a sheet that is in a predetermined range upstream of the processing means, and the control means is further configured to stop the transport of the first sheet in the predetermined range when the transport of the first sheet is stopped upstream of the processing means.

8. The sheet processing apparatus according to claim 7, wherein the housing of the sheet processing apparatus is provided with a door for a user to remove sheets in the predetermined range.

9. The sheet processing device according to any one of claims 1 to 8, wherein the control means is further configured to present a procedure for removing the first sheet to a user when transport of the first sheet is stopped upstream of the processing means.

10. A sheet processing apparatus according to any one of claims 1 to 9, wherein the sheet is transported to the sheet processing apparatus from an image forming apparatus that forms an image on the sheet, and the control means is further configured to determine whether the sheet transported from the image forming apparatus is the target of the processing based on information about the sheet received from the image forming apparatus.

11. The sheet processing apparatus according to any one of claims 1 to 10, wherein the control means is further configured to determine whether or not the sheet is a target for the processing by measuring the size of the sheet.

Images