Sheet processing apparatus and image forming system

Abstract

To provide an image reading apparatus, a sheet processing apparatus, and an image forming system that can improve the degree of freedom in the combination of apparatuses.SOLUTION: An image reading apparatus reads an image of a sheet and ejects the sheet toward a sheet processing apparatus for performing post-processing on the sheet, and the image reading apparatus comprises: a reading unit that reads the image of the sheet; an acquisition unit that acquires a result of inspection processing of determining the presence or absence of an image defect in the sheet based on the image read by the reading unit; and a transmission unit that transmits an ejection timing signal indicating the timing to eject the sheet to the sheet processing apparatus via a signal line. When ejecting a sheet for which it is determined that there is not an image defect in the inspection processing, the transmission unit outputs the ejection timing signal having a first waveform to the signal line, and when ejecting a sheet for which it is determined that there is an image defect in the inspection processing, outputs the ejection timing signal having a second waveform different from the first waveform to the signal line.SELECTED DRAWING: Figure 11

Description

[Technical field]

[0001] The present invention , S The present invention relates to a sheet processing apparatus that processes sheets and an image forming system that includes the same. [Background technology]

[0002] Conventionally, in an image forming system that combines multiple devices to perform in-line bookbinding, a relay device has been proposed that is placed between the image forming device and the post-processing device (see Patent Document 1). This relay device performs serial communication with the image forming device and parallel communication with the post-processing device. The relay device outputs a set separation signal, separate from the paper discharge signal, to the post-processing device in synchronization with the paper discharge signal for the last sheet of a set of printed material output by the image forming device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-035380 A Summary of the Invention [Problem to be solved by the invention]

[0004] The relay device described in Patent Document 1 outputs a paper ejection signal and a set separation signal to the post-processing device via parallel communication, and required a signal line for outputting the set separation signal in addition to the signal line for outputting the paper ejection signal.

[0005] In an inline configuration with an inspection module that checks the quality of output products, the post-processing device must be notified of the inspection results in order to change the operation of the post-processing device according to the inspection results. When a signal is output to the post-processing device by parallel communication as in Patent Document 1, an additional port must be installed in the post-processing device to receive a signal line for notifying the inspection results. This reduces the degree of freedom in device combinations in an inline configuration.

[0006] Therefore, the present invention can improve the degree of freedom in device combination. Nasi The present invention aims to provide a printer processing device and an image forming system. [Means for solving the problem]

[0007] The present invention relates to The image forming unit forms an image on a sheet, and an inspection unit reads the image on the sheet formed by the image forming unit and inspects for image defects. image formation Device A sheet processing apparatus that performs post-processing on a sheet discharged from the sheet processing apparatus. In a post-processing section for processing a sheet discharged from the image forming apparatus; The timing signal is sent via the signal line. Receiving receiver and, A control unit that controls the post-processing unit based on the discharge timing signal received by the receiving unit; Equipped with the control unit, when the receiving unit receives the discharge timing signal having a first waveform output when a sheet determined to have no image defects by the inspection unit is discharged, executes a first process on the sheet by the post-processing unit, and, when the receiving unit receives the discharge timing signal having a second waveform different from the first waveform output when a sheet determined to have an image defect by the inspection unit is discharged, executes a second process on the sheet by the post-processing unit, different from the first process. It is characterized by:

[0008] The present invention also provides a method for producing a method for manufacturing a semiconductor device comprising the steps of: a control unit that controls the post-processing unit based on the last-sheet signal received by the receiving unit, the control unit controlling ... It is characterized by: Effect of the Invention

[0010] According to the present invention, the degree of freedom in combining devices can be improved. [Brief description of the drawings]

[0011] [Figure 1] 1 is an overall schematic diagram showing an image forming system according to a first embodiment. [Diagram 2] FIG. [Diagram 3] FIG. 4 is an explanatory diagram showing signal lines of a communication cable. [Figure 4] 4 is a timing chart showing changes in each signal. [Diagram 5] FIG. 1A is a diagram showing a reference image according to this embodiment; FIG. 1B is a diagram showing an image of a good product that matches the reference image; FIG. 1C is a diagram showing an image of a defective product with a stain; and FIG. 1D is a diagram showing an image of a defective product with a chip. [Figure 6] 5 is a flowchart showing an operation related to signal transmission and reception of the image forming apparatus. [Figure 7] 6 is a flowchart showing an operation related to signal transmission and reception of the sheet processing apparatus. [Figure 8]FIG. 1A is a timing chart showing the waveform of a discharge timing signal output from an image forming apparatus, FIG. 1B is a timing chart showing a discharge timing signal having a pulse width of T1, and FIG. 1C is a timing chart showing a discharge timing signal having a pulse width of T2. [Figure 9] 6 is a flowchart showing an operation related to signal transmission and reception of the image forming apparatus when performing an inspection process. [Figure 10] 11 is a flowchart showing a process of sorting the deliverables by set based on a discharge timing signal. [Figure 11] 11 is a flowchart showing a process of sorting the deliverables by set based on a discharge timing signal. [Figure 12] FIG. 1A is a timing chart showing the waveform of a discharge timing signal output from an image forming apparatus, FIG. 1B is a timing chart showing a discharge timing signal with one pulse, and FIG. 1C is a timing chart showing a discharge timing signal with two pulses. [Figure 13] FIG. 11 is a block diagram showing a control block according to a third embodiment. [Figure 14] 1A is a timing chart showing the waveform of a discharge timing signal output from an image forming apparatus, FIG. 1B is a timing chart showing a discharge timing signal having a voltage V1, and FIG. 1C is a timing chart showing a discharge timing signal having a voltage V2. [Figure 15] 10A is a timing chart showing waveforms of a discharge timing signal and a final sheet signal according to the fourth embodiment when all sheets in a set pass inspection, and FIG. 10B is a timing chart showing waveforms of a discharge timing signal and a final sheet signal according to the fourth embodiment when a sheet in a set fails inspection. [Figure 16] 13A is a timing chart showing a final paper signal having a pulse width of T1, and FIG. 13B is a timing chart showing a final paper signal having a pulse width of T2. [Figure 17] 6 is a flowchart showing an operation related to signal transmission and reception of the image forming apparatus when performing an inspection process. [Figure 18]6 is a flowchart showing an operation related to signal transmission and reception of the image forming apparatus when performing an inspection process. [Figure 19] 11 is a flowchart showing a process for sorting deliverables by copy based on a last-sheet signal. [Figure 20] 11 is a flowchart showing a process for sorting deliverables by copy based on a last-sheet signal. [Figure 21] 11 is a flowchart showing a process of sorting the deliverables by set based on a discharge timing signal and a last-sheet signal. [Figure 22] 11 is a flowchart showing a process of sorting the deliverables by set based on a discharge timing signal and a last-sheet signal. [Figure 23] 11 is a table showing the correspondence between the process contents performed by the sheet processing apparatus and sheet reception response signals. [Figure 24] 4 is a timing chart showing waveforms of a discharge timing signal output from the image forming apparatus and a sheet reception response signal output from the sheet processing apparatus. [Diagram 25] 11 is a flowchart showing a process for notifying a post-processing result on a sheet-by-sheet basis. [Figure 26] 11 is a flowchart showing a process for notifying a post-processing result on a sheet-by-sheet basis. [Figure 27] 10 is a flowchart for explaining a process for notifying an operation unit that an escape ejection process has been executed. [Figure 28] 5A and 5B are diagrams showing examples of screens displayed on an operation unit. [Figure 29] A table showing the combination of inspection results and expected sorting processes. [Diagram 30] 6 is a flowchart showing an operation related to signal transmission and reception of the image forming apparatus when performing an inspection process. [Diagram 31] 6 is a flowchart showing an operation related to signal transmission and reception of the image forming apparatus when performing an inspection process. [Diagram 32] 11 is a flowchart for explaining a notification process that is performed based on a comparison between an inspection result and an expected sorting process. [Diagram 33]11 is a flowchart for explaining a notification process that is performed based on a comparison between an inspection result and an expected sorting process. [Diagram 34] 11A and 11B are diagrams showing a confirmation message displayed on the operation unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The best mode for carrying out the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the embodiments may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions, and the scope of the present invention is not limited to the following embodiments.

[0013] <First embodiment> [Overall structure] First, a first embodiment of the present invention will be described. As shown in Fig. 1, an image forming system 1 according to the first embodiment includes an image forming apparatus 10, an operation unit 20, a document reading apparatus 30, and a sheet processing apparatus 1000. The sheet processing apparatus 1000 is in-line connected to the downstream side of the image forming apparatus 10 in the sheet conveying direction.

[0014] The document reading device 30 can read an image of a document placed on a document tray 31 or a document glass table 32 by a scanner unit 100. The operation unit 20 has a liquid crystal panel and various physical buttons, etc., and can be used to input various settings related to the image forming system 1 and to instruct the execution of a job.

[0015] The image forming apparatus 10 as an image reading device is an electrophotographic full-color laser printer that forms a toner image on a sheet based on an image signal input from an information processing device such as a personal computer or an original reading device 30. The image forming apparatus 10 is a POD machine that can handle printing other than general office use, and can use various sheets as recording media, such as paper and envelopes, glossy paper, plastic films such as overhead projector sheets (OHT), and cloth.

[0016] Image forming apparatus 10 has a feeding unit 40 that feeds a sheet, an image forming section 50 that forms an image on the sheet fed from the feeding unit 40, and a fixing device 60 that fixes the toner image formed on the sheet by the image forming section 50. Image forming apparatus 10 also has a discharge section 70 that discharges the sheet on which the image has been formed, and a reversing conveying section 80 that reverses and conveys the sheet.

[0017] The image forming section 50 is of a tandem intermediate transfer type equipped with four process units PY, PM, PC, and PK that form yellow, magenta, cyan, and black toner images, and an intermediate transfer belt 104 that serves as an intermediate transfer body. Each of the process units PY to PK is an electrophotographic unit that has a photosensitive drum that serves as a photosensitive body.

[0018] Since the process units PY to PK have the same configuration except for the color of the toner used for development, the configuration of the process units and the toner image forming process (image forming operation) will be described using the yellow process unit PY as an example. In addition to the photosensitive drum 102, the process unit PY has a charging device 91, an exposure device 103, a developing device 92, etc. The photosensitive drum 102 is a drum-shaped photosensitive body having a photosensitive layer on its outer periphery, and rotates in a direction parallel to the rotation direction of the intermediate transfer belt 104. The surface of the photosensitive drum 102 is charged by being supplied with an electric charge from the charging device 91.

[0019] The exposure device 103 emits a laser beam modulated according to image information and scans the photosensitive drum 102 by an optical system, thereby drawing an electrostatic latent image on the surface of the photosensitive drum 102. An exposure control unit temperature sensor (not shown) is provided inside the exposure device 103, and can detect the temperature inside the exposure device 103. The development device 92 contains a developer including toner, and develops the electrostatic latent image into a toner image by supplying the toner to the photosensitive drum 102. The toner image formed on the photosensitive drum 102 is primarily transferred to the intermediate transfer belt 104 at a primary transfer portion, which is a nip portion between a primary transfer roller 105Y, which is a primary transfer device, and the intermediate transfer belt 104.

[0020] The intermediate transfer belt 104 is driven to rotate in a clockwise direction in the figure. The above-mentioned image forming operation is carried out in parallel in each of the process units PY to PK, and the four color toner images are transferred in a multi-layer manner so that they overlap each other, thereby forming a full-color toner image on the intermediate transfer belt 104. This toner image is carried by the intermediate transfer belt 104 and transported to a secondary transfer section. The secondary transfer section is configured as a nip section between a secondary transfer roller 106 and a secondary transfer inner roller 107.

[0021] In parallel with such image forming operation, a sheet is fed from the feeding unit 40. The feeding unit 40 has two cassettes 110a, 110b for accommodating sheets. The sheet fed from the feeding unit 40 is conveyed to a pair of registration rollers 111, where skew correction and timing correction are performed, and then the sheet is conveyed toward the secondary transfer section. At this time, the pair of registration rollers 111 sends the sheet to the secondary transfer section at a timing that matches the progress of the image forming operation by the process units PY to PK, based on a detection signal from a registration sensor (not shown).

[0022] A bias voltage of a polarity opposite to the charge polarity of the toner is applied to a secondary transfer roller 106, so that the toner image is secondarily transferred onto the sheet fed into the secondary transfer section. Residual toner remaining on the intermediate transfer belt 104 after transfer is removed by a belt cleaner 108. In addition, a plurality of color shift amount reading sensors 109 are arranged in parallel in the main scanning direction perpendicular to the moving direction of the intermediate transfer belt 104 near the intermediate transfer belt 104. The color shift amount reading sensors 109 read the toner images on the intermediate transfer belt 104. The image forming apparatus 10 then calculates the amount of shift between a predetermined reference color and each color using the reading results of the color shift amount reading sensors 109, and feeds the calculated shift amount back to the image forming conditions.

[0023] The sheet onto which the toner image has been transferred is delivered to the fixing device 60. The fixing device 60 has a pair of fixing rollers that sandwich and transport the sheet, a heat source such as a halogen heater, and a temperature sensor 131, and applies pressure and heat to the toner image carried on the sheet, thereby melting and fixing the toner particles to obtain a fixed image fixed on the sheet.

[0024] After the image has been fixed by the fixing device 60, the sheet is conveyed to a reversing path 123 or a conveying path 124 by a switching member 122. When the image formation on the sheet is complete, the sheet is guided to the conveying path 124, and the leading edge of the sheet is detected by an inspection entrance sensor 140. Based on the detection result of the inspection entrance sensor 140, a sheet reading sensor 121 as a reading unit starts reading the images on the front and back of the sheet.

[0025] Downstream of the sheet reading sensor 121 in the sheet conveying direction, an inspection exit roller pair 113, an exit sensor 141, and a discharge roller pair 112 are arranged, and the conveying path 124 has a curved portion between the inspection exit roller pair 113 and the discharge roller pair 112. This curved portion is alternately bent in the front-to-back direction of the sheet, and is configured to be longer than the longest sheet that the image forming apparatus 10 can feed. This reduces curling of the sheet passing through the conveying path 124 caused by heat received from the fixing device 60. The exit sensor 141 is used to monitor the sheet conveying status and to generate a discharge timing signal to the sheet processing apparatus 1000 described later.

[0026] When an image is formed on the back side of the sheet, the sheet is guided to a reversing path 123 by a switching member 122. The sheet guided to the reversing path 123 is reversed by a reversing conveying section 80 and conveyed again to the registration roller pair 111. Then, after an image is formed on the back side of the sheet, the sheet is delivered to the sheet processing apparatus 1000. Note that the above configuration is an example of an image forming apparatus, and the image forming apparatus may be provided with an inkjet type image forming means instead of an electrophotographic type image forming means, for example.

[0027] [Sheet processing device] Next, a configuration of the sheet processing apparatus 1000 will be described. The sheet processing apparatus 1000 has functions of performing post-processing such as a sheet storage process for storing sheets in a sheet storage unit 1003, a bundle alignment process for bundling a plurality of sheets stored in the sheet storage unit 1003 into a sheet bundle, a binding process, and a sorting process. The binding process is a process for stapling the sheet bundle, and the sorting process is a process for discharging sheets or sheet bundles to different trays.

[0028] The sheet processing apparatus 1000 has a binding processing section 1100 capable of performing a binding process on sheets, and a discharge section 1200 as a post-processing section that discharges sheets. The binding processing section 1100 has a sheet storage section 1003 that stores sheets, a positioning member 1004 against which the leading edge of the sheet abuts, a stapler 1005, a pushing member 1006, and a pair of folding rollers 1007. The discharge section 1200 has a purge conveying path 1050, a conveying branch guide 1051, a purge tray 1053, a first discharge path 1009, a second discharge path 1010, a switching member 1008, a first discharge tray 1012, and a second discharge tray 1014.

[0029] When a sheet is discharged to the purge tray 1053, the conveying branch guide 1051 is driven, and the sheet is guided to the purge conveying path 1050 by the conveying branch guide 1051. The sheet guided to the purge conveying path 1050 is discharged to the purge tray 1053 by a plurality of conveying roller pairs 1052. A switching member 1008 switches the conveying destination of the sheet to either a first discharge path 1009 or a second discharge path 1010.

[0030] When the sheet is not purged, the sheet conveyed by the pair of inlet rollers 1001 is guided by the conveyance branch guide 1051 toward the pair of conveyance rollers 1002. The sheet is then discharged by the pair of conveyance rollers 1002 to a sheet storage unit 1003. The sheet storage unit 1003 stores the sheet while guiding the sheet to a positioning member 1004. The positioning member 1004 is supported so as to be movable in the vertical direction, and determines the leading edge position of the sheet according to its position.

[0031] For example, when saddle-stitching is performed on sheets, the positioning member 1004 is positioned so that the center of the sheet stack corresponds to the position of the stapler 1005. After the stapler 1005 has stapled the center of the sheet stack, the positioning member 1004 moves so that the center of the sheet stack corresponds to the position of the protruding member 1006.

[0032] Thereafter, the sheet bundle is pushed out by a pushing member 1006 into the nip of a pair of folding rollers 1007, and the sheet bundle is folded by the pair of folding rollers 1007. As a result, the sheet bundle is saddle-stitched and bound.

[0033] The sheet stack that has been saddle-stitched is discharged outside the apparatus by a discharge section 1200. When the sheet stack is guided to a first discharge path 1009 by a switching member 1008, the sheet stack is discharged to a first discharge tray 1012 by a conveyor belt 1011. When the sheet stack is guided to a second discharge path 1010 by the switching member 1008, the sheet stack is discharged to a second discharge tray 1014 by a conveyor belt 1013.

[0034] In this way, the binding processing unit 1100 performs a bundle alignment process in which multiple sheets are aligned and bound into a sheet bundle, and a binding process in which the sheet bundle is stapled, and the discharge unit 1200 performs a sorting process in which sheets or sheet bundles are discharged to different trays.

[0035] In this embodiment, if an inspection process (test process) using the detection results of the sheet reading sensor 121 determines that the image formed on the sheet is normal, i.e., that there is no image defect, the sheet bundle is discharged to the first discharge tray 1012. If the inspection process determines that the image formed on the sheet is abnormal, i.e., that there is an image defect, the sheet bundle is discharged to the second discharge tray 1014. That is, the inspection process determines whether or not there is an image defect on the sheet, and the discharge section 1200 of the sheet processing device 1000 switches the discharge destination of the sheet bundle depending on the result of the inspection process.

[0036] In the present embodiment, the saddle stitching process is performed by the sheet processing apparatus 1000, but the binding processing unit 1100 may only fold the sheet stack without binding the sheet stack with the stapler 1005. The stapler 1005 may bind the sheet stack not only at the center of the sheets, but also at other parts. The sheet processing apparatus 1000 may not have the binding processing unit 1100, and may simply use the discharge unit 1200 to distribute and discharge the sheet stack or sheets to the first discharge tray 1012 or the second discharge tray 1014.

[0037] [Control Block] Next, a control block of the image forming system 1 according to the present embodiment will be described. As shown in Fig. 2, the image forming system 1 has a printer control unit 200 provided in the image forming apparatus 10, and a post-processing control unit 600 provided in the sheet processing apparatus 1000. The printer control unit 200 and the post-processing control unit 600 are connected by a communication cable 250.

[0038] The printer control unit 200 has a CPU 201 that performs basic control of the image forming apparatus 10, a ROM 205 in which a control program and an application program are stored, and a RAM 202 that functions as a work area for executing the processing of the control program. The printer control unit 200 also has an input / output port IC 203, communication I / Fs 204 and 209, an image memory unit 206, an image processing unit 207, an operation unit 208, an inspection processing unit 210, a timer 220, and a battery 240. Note that I / F is an abbreviation for interface.

[0039] The image memory unit 206 accumulates image data. The image processing unit 207 processes the image signal converted into an electrical signal. The inspection processing unit 210 as an acquisition unit performs an inspection process described below and acquires the result of the inspection process. The battery 240 is connected to the RAM 202, and the data in the RAM 202 is retained even when the image forming apparatus 10 is turned off.

[0040] The input / output port IC203 is connected to the CPU 201 via an address bus and a data bus. The CPU 201 inputs signals from sensors (not shown) through the input / output port IC203 and outputs control signals for various loads (not shown) such as motors and clutches in accordance with the contents of a control program stored in the ROM 205. The CPU 201 then outputs the control signals to control sheet transport, image formation on sheets, and the like.

[0041] A sheet reading sensor 121 that reads the front and back of the sheet after image formation is connected to the inspection processing unit 210. The inspection processing unit 210 receives image data of the image converted into an electric signal by the sheet reading sensor 121, and performs an inspection process to compare the image data with a reference image to determine whether the image data is good or bad. For example, document image data stored in the image memory unit 206 is used as the reference image.

[0042] The CPU 201 is connected to the operation unit 20, and controls display control and key input on the operation unit 20. A user can instruct the CPU 201 to switch the operation mode of the image forming apparatus 10 and the display on the operation unit 20 through key input on the operation unit 20. The CPU 201 can also control the display unit, such as a liquid crystal panel of the operation unit 20, to display the operation state of the image forming apparatus 10 and the operation mode set by key input.

[0043] The printer control unit 200 is also connected to the information processing device 800 via a communication I / F 209. The CPU 201 accumulates image data transferred from the information processing device 800 in an image memory unit 206, and performs image processing using an image processing unit 207. Furthermore, the CPU 201 transmits and receives parallel signals to and from the post-processing control unit 600 via a communication I / F 204 and a communication cable 250 as a transmission unit, thereby controlling the sheet processing device 1000, such as sheet delivery, status display, and the like.

[0044] Here, a description will be given of information contained in the parallel signals that the CPU 201 communicates with the post-processing control unit 600. These parallel signals include information for instructing ON / OFF of the operation of the post-processing control unit 600, such as a discharge timing signal 401, a last sheet signal 402, an operation instruction signal 403, a sheet reception response signal 404, and a last sheet processing end signal 405, which will be described later. The CPU 201 thus performs image formation, and also performs processing related to the configuration of the image forming system 1.

[0045] The post-processing control unit 600 includes a CPU 601 that performs basic control of the sheet processing apparatus 1000, a ROM 605 that stores a control program and an application program, and a RAM 602 that functions as a work area for executing the processing of the control program. The post-processing control unit 600 also includes an input / output port IC 603, a communication I / F 604, and a timer 620.

[0046] The input / output port IC 603 is connected to the CPU 601 via an address bus and a data bus. The CPU 601 inputs signals from sensors (not shown) through the input / output port IC 603 and outputs control signals for various loads (not shown) such as motors and clutches in accordance with the contents of a control program stored in the ROM 605. By outputting the control signals, the CPU 601 controls sheet transport, post-processing of sheets, and the like.

[0047] The CPU 601 controls the operation of inline post-processing functions such as delivery and post-processing of sheets conveyed from the image forming apparatus 10 by transmitting and receiving parallel signals to and from the printer control unit 200 via the communication I / F 604 and the communication cable 250. The CPU 601 also counts the number of sheets delivered from the image forming apparatus 10 from the leading sheet of a sheet stack to be post-processed, and stores this in the RAM 602 as the number of delivered sheets.

[0048] [Signal line of communication cable] Next, the signal lines of the communication cable 250 of the parallel communication system that connects the communication I / Fs 204 and 604 will be described with reference to Fig. 3. As shown in Fig. 3, the communication cable 250 has a discharge timing signal line 2501, a last sheet signal line 2502, and an operation instruction signal line 2503 as output signal lines from the image forming apparatus 10 to the sheet processing apparatus 1000. The communication cable 250 also has a sheet receipt response signal line 2504 and a last sheet processing end signal line 2505 as signal lines for sending signals from the sheet processing apparatus 1000 to the image forming apparatus 10. The roles and timing of the signals transmitted by each of the five signal lines will be described later.

[0049] [Details of each signal] Next, the details of signals transmitted through each signal line of the communication cable 250 will be described with reference to Fig. 4. Fig. 4 is a timing chart showing changes in each signal exchanged between the image forming apparatus 10 and the sheet processing apparatus 1000 according to the present embodiment.

[0050] First, the role of each signal line will be described. As shown in FIG. 4, the discharge timing signal 401 is a signal controlled by the image forming apparatus 10, and is transmitted to the sheet processing apparatus 1000 by the discharge timing signal line 2501 as the above-mentioned signal line. The discharge timing signal 401 is a signal used by the sheet processing apparatus 1000 to generate timing for starting sheet reception preparation processing by rotating the pair of entrance rollers 1001 at the sheet reception speed. For this reason, the sheet position and the signal issuing timing are predefined between the image forming apparatus 10 and the sheet processing apparatus 1000. In this embodiment, the discharge timing signal 401 is issued at the timing when the leading edge of the sheet reaches the sheet receiving port of the sheet processing apparatus 1000 based on the detection result of the exit sensor 141. That is, the discharge timing signal 401 indicates the timing for discharging the sheet from the image forming apparatus 10.

[0051] The last-sheet signal 402 is a signal controlled by the image forming apparatus 10, and is transmitted to the sheet processing apparatus 1000 via a last-sheet signal line 2502 as a signal line. The last-sheet signal 402 is a signal indicating that the sheet handed over by the image forming apparatus 10 to the sheet processing apparatus 1000 is the last sheet of a set (sheet stack), i.e., the last sheet. Based on the last-sheet signal 402, the sheet processing apparatus 1000 determines whether or not post-processing can be performed on the sheet stack held in the sheet storage unit 1003.

[0052] The operation instruction signal 403 is a signal controlled by the image forming apparatus 10, and is transmitted to the sheet processing apparatus 1000 via an operation instruction signal line 2503. The operation instruction signal 403 is a signal by which the image forming apparatus 10 notifies the sheet processing apparatus 1000 of the start and end of a job. Upon detecting the rising edge of the operation instruction signal 403, the sheet processing apparatus 1000 performs initialization processing to set the sheet processing apparatus 1000 in a state where post-processing is possible, and performs operation stop processing of the sheet processing apparatus 1000 upon detecting the falling edge.

[0053] The sheet reception response signal 404 is a signal controlled by the sheet processing apparatus 1000, and is transmitted to the image forming apparatus 10 via a sheet reception response signal line 2504. The sheet reception response signal 404 is a signal output to indicate that the sheet processing apparatus 1000 has completed necessary processing of the received sheet. The processing of the sheet refers to, for example, storing the sheet in the sheet storage unit 1003 described above, or discharging the sheet to the second discharge tray 1014.

[0054] The final sheet processing end signal 405 is a signal controlled by the sheet processing apparatus 1000, and is transmitted to the image forming apparatus 10 by a final sheet processing end signal line 2505 as a signal line. The final sheet processing end signal 405 is a signal that the sheet processing apparatus 1000 outputs to the image forming apparatus 10 upon receiving the final sheet signal 402 to indicate that post-processing of the sheet stack has been completed. Post-processing of the sheet stack refers to, for example, the binding process or sorting process described above. Upon receiving the final sheet processing end signal 405 for the last copy of the job, the image forming apparatus 10 determines that all processing of the job has been completed, and turns off the operation instruction signal 403 described above.

[0055] The discharge timing signal 401, the last paper signal 402, the sheet reception response signal 404, and the last paper processing end signal 405 are notifications by pulse signals, and it is predefined that the pulse width is equal to or greater than width T1 between the image forming apparatus 10 and the sheet processing apparatus 1000. The operation instruction signal 403 is a notification by a signal level, and when it is High, it means that a job is being executed, and when it is Low, it means that a job is not being executed.

[0056] Although the pulse widths shown in FIG. 4 are all standardized to width T1, it does not matter if all the pulse widths are not the same as long as the pulse width specifications match between the image forming apparatus 10 and the sheet processing apparatus 1000.

[0057] Next, the timing of changes in the above-mentioned five signals during a job will be described with reference to Fig. 4. The CPU 201 of the image forming apparatus 10 starts print job processing when a print command is received from the operation unit 20, the information processing apparatus 800, or the like. When the CPU 201 starts a job, it turns on the operation command signal 403 via the communication I / F 204. Then, the CPU 601 of the sheet processing apparatus 1000 detects the rising edge of the operation command signal 403 via the communication I / F 604, and starts initialization processing such as detecting the home positions of various mechanisms and starting motor drive.

[0058] Next, the image forming apparatus 10 performs image formation and inspection processing on the sheet, and then discharges the sheet. At this time, the CPU 201 outputs a discharge timing signal 401 from the communication I / F 204. As described above, the discharge timing signal 401 is specified to be issued at the timing when the leading edge of the sheet reaches the sheet receiving opening of the sheet processing apparatus 1000, so the CPU 201 generates the discharge timing signal 401 based on this timing.

[0059] Specifically, after the exit sensor 141 connected to the input / output port IC 203 detects the leading edge of the sheet, the timer 220 is used to wait for the time it takes for the sheet to be transported from the exit sensor 141 to the outlet of the image forming apparatus 10, and then the discharge timing signal 401 is output. The wait time can be calculated, for example, from the length from the exit sensor 141 to the outlet of the image forming apparatus 10 and the transport speed of the sheet. In addition, if the sheet is the last sheet of a set, the CPU 201 outputs a last sheet signal 402 from the communication I / F 204.

[0060] The sheet processing apparatus 1000 starts a sheet receiving process when it receives a discharge timing signal 401. When the sheet received from the image forming apparatus 10 is completely stored in the sheet storage unit 1003, the sheet processing apparatus 1000 outputs a sheet receiving response signal 404 to the image forming apparatus 10.

[0061] Furthermore, when the sheet processing apparatus 1000 receives the last sheet signal 402 simultaneously with the discharge timing signal 401, it determines that the sheet is the last sheet of the set. After the sheet receiving process is completed, post-processing is performed on the sheet stack in the sheet storage unit 1003. Then, when the sheet processing apparatus 1000 has completed discharging the sheet stack to the first discharge tray 1012 or the second discharge tray 1014 via the conveyor belt 1011 or the conveyor belt 1013, it outputs a last sheet processing end signal 405 to the image forming apparatus 10.

[0062] When the CPU 201 of the image forming apparatus 10 receives the final sheet processing end signal 405 via the communication I / F 204, it turns off the operation instruction signal 403 and performs a stop process to stop the image forming apparatus 10. Also, when the CPU 601 of the sheet processing apparatus 1000 detects a falling edge of the operation instruction signal 403 via the communication I / F 604, it determines that the job has ended and performs a stop process to stop the image forming apparatus 10.

[0063] [Inspection process] FIG. 5(a) is a diagram showing a reference image according to this embodiment, and FIGS. 5(b)-(c) are diagrams showing each image formed on a sheet. As shown in FIG. 5(a), for example, a document image stored in the image memory unit 206 is used as the reference image 500. The inspection processing unit 210 performs an inspection process by comparing the reference image 500 read from the image memory unit 206 with the image data on the sheet read by the sheet reading sensor 121. As shown in FIG. 5(b), when an image 501 is obtained from the sheet reading sensor 121, it is compared with the reference image and is found to match, so that the inspection processing unit 210 judges the image 501 to be a non-defective product.

[0064] On the other hand, as shown in FIG. 5(c), when image 502 is compared with reference image 500, it is found that there is a stain in the "D" portion, and therefore the inspection processing unit 210 judges image 502 to be a defective product. Similarly, as shown in FIG. 5(d), when image 503 is compared with reference image 500, it is found that the "D" portion is missing, and therefore the inspection processing unit judges image 503 to be a defective product. That is, the inspection processing unit 210 judges that image 501 does not have an image defect, and judges that images 502 and 503 have an image defect. Note that the inspection processing unit 210 may be configured to acquire the result of inspection processing performed in a device other than the image forming apparatus 10.

[0065] [Image formation operation] FIG. 6 is a flowchart showing the operation of the image forming apparatus 10 according to the present embodiment with respect to the transmission and reception of signals. The flowchart shown in FIG. 6 shows the operation of the image forming apparatus 10 with respect to the transmission and reception of signals when the inspection processing unit 210 does not perform the inspection processing. First, as shown in FIG. 6, the CPU 201 in the printer control unit 200 turns on the operation instruction signal 403 through the communication I / F 204 (step S1). Next, the CPU 201 waits until the leading edge of the conveyed sheet arrives at the discharge outlet of the image forming apparatus 10 (step S2). For example, the CPU 201 can know whether the leading edge of the sheet has reached the discharge outlet by the exit sensor 141 connected to the input / output port IC203. Then, when it is determined that the leading edge of the sheet has reached the discharge outlet of the image forming apparatus 10 (step S2: Yes), the CPU 201 outputs the discharge timing signal 401 from the communication I / F 204 (step S3).

[0066] Next, CPU 201 determines whether the sheet is the last sheet of the set (step S4). This determination is realized using control information stored in RAM 202, such as the number of sheets in the print job and the serial number from the start of the job of the sheet whose top sheet is at the discharge outlet. If it is determined to be the last sheet of the set (step S4: Yes), CPU 201 outputs a last sheet signal 402 from communication I / F 204 (step S5). On the other hand, if it is determined to not be the last sheet of the set (step S4: No), CPU 201 does not instruct communication I / F 204 to output last sheet signal 402.

[0067] Next, the CPU 201 judges whether the sheet is the last sheet of the job (step S6). This judgment is realized by using control information stored in the RAM 202, such as the number of sheets in the print job, the number of jobs, and the serial number of the sheet whose top is at the discharge outlet from the start of the job. If it is judged to be the last sheet of the job (step S6: Yes), the CPU 201 waits for the reception of the last sheet processing end signal 405 by the communication I / F 204 (step S7). If the last sheet processing end signal 405 is received (step S7: Yes), the CPU 201 turns off the operation instruction signal 403 (step S8) and ends the flow. On the other hand, if it is judged in step S6 that the sheet is not the last sheet of the job (step S6: No), the CPU 201 returns to the process of step S2.

[0068] 7 is a flowchart showing the operation of the sheet processing apparatus 1000 according to this embodiment regarding the transmission and reception of signals. The flowchart shown in FIG. 7 shows the operation of the sheet processing apparatus 1000 regarding the transmission and reception of signals when the inspection processing unit 210 does not perform the inspection processing. First, as shown in FIG. 7, the CPU 601 judges whether the operation instruction signal 403 is ON or not by the communication I / F 604 (step S11). If it is judged that the operation instruction signal 403 is ON (step S11: Yes), the CPU 601 performs an initialization process (step S12). Here, the initialization process is a drive control of the inlet roller pair 1001 for receiving the sheet discharged from the image forming apparatus 10, and the like.

[0069] Next, the CPU 601 judges whether or not the discharge timing signal 401 has been received (step S13). If it is judged that the discharge timing signal 401 has been received (step S13: Yes), the CPU 601 performs a sheet storage process (step S14). Next, the CPU 601 judges whether or not the sheet storage process has been completed (step S15). At the entrance of the sheet storage unit 1003, a storage unit entrance sensor 1015 is provided which turns ON when a sheet arrives thereat. The CPU 601 judges that the sheet storage process has been completed based on the elapse of a time period corresponding to the distance from the detection position of the storage unit entrance sensor 1015 to the positioning member 1004 after the storage unit entrance sensor 1015 turns ON.

[0070] If it is determined that the sheet storage process is completed (step S15: Yes), the CPU 601 outputs a sheet reception response signal 404 to the image forming apparatus 10 (step S16). Then, the CPU 601 determines whether or not the last sheet signal 402 is received (step S17). If it is determined that the last sheet signal 402 is not received (step S17: No), the CPU 601 returns to the process of step S13. On the other hand, if it is determined that the last sheet signal 402 is received (step S17: Yes), the CPU 601 performs post-processing for each set (step S18). For example, in the case of saddle stitching, the post-processing for each set corresponds to folding and binding by stapling. Then, the CPU 601 discharges the sheet stack in the sheet storage unit 1003 to the first discharge tray 1012 or the second discharge tray 1014, and outputs a last sheet process completion signal 405 to the image forming apparatus 10 (step S19).

[0071] Next, the CPU 601 judges whether or not the ejection timing signal 401 has been received (step S20). If it is judged that the ejection timing signal 401 has been received (step S20: Yes), the CPU 601 returns to the process of step S14. On the other hand, if it is judged that the ejection timing signal 401 has not been received (step S20: No), the CPU 601 judges whether or not the operation instruction signal 403 is OFF (step S21). If it is judged that the operation instruction signal 403 is ON (step S21: No), the CPU 601 returns to the process of step S20.

[0072] If it is determined that the operation instruction signal 403 is OFF (step S21: Yes), the CPU 601 performs a stop process (step S22) and ends the flow. The stop process here is to stop driving the pair of inlet rollers 1001, etc.

[0073] [Superimposition of inspection results on discharge timing signal] 8(a) to 8(c) are timing charts for explaining a means for superimposing the inspection result for each sheet on the discharge timing signal 401 according to this embodiment, and a method for the sheet processing apparatus 1000 to interpret the inspection result from the discharge timing signal 401. More specifically, FIG. 8(a) is a timing chart showing the waveform of the discharge timing signal 401 output from the image forming apparatus 10. FIGS. 8(b) and 8(c) are timing charts for explaining the interpretation of the discharge timing signal 401 received by the sheet processing apparatus 1000. There are two types of discharge timing signals 401, discharge timing signals 401a and 401b, which will be described later, for the discharge timing signal 401.

[0074] In this embodiment, the CPU 201 inquires of the inspection result of the sheet to the inspection processing unit 210 before outputting the discharge timing signal 401. Then, if the inspection result is OK, that is, if the sheet is of good quality and there is no image defect, the CPU 201 outputs a discharge timing signal 401a having a first pulse width T1 from the communication I / F 204 to the sheet processing apparatus 1000, as shown in Fig. 8(a). That is, the discharge timing signal 401a has a first waveform.

[0075] On the other hand, when the inspection result is "NG", that is, when the product is defective and there is an image defect, the CPU 201 outputs a discharge timing signal 401b having a second pulse width T2 to the sheet processing apparatus 1000 from the communication I / F 204. Since the width T2 is larger than the width T1, the discharge timing signal 401b has a second waveform different from the first waveform. For example, the signal output from the image forming apparatus 10 has a discharge timing signal 401a corresponding to the first sheet, a discharge timing signal 401b corresponding to the second sheet, and a discharge timing signal 401a corresponding to the third sheet. This signal is a signal when printing three sheets per copy, and indicates that the inspection results of the first and third sheets are "OK" and the inspection result of the second sheet is "NG".

[0076] 8(b) and (c), the interpretation of the inspection result in the sheet processing apparatus 1000 will be described. When the discharge timing signal 401 is output from the image forming apparatus 10, the CPU 601 of the sheet processing apparatus 1000 first detects the rising edge of the discharge timing signal 401 via the communication I / F 604. Then, the CPU 601 samples the logical value of the discharge timing signal 401 when a time of (T1+T2) / 2 has elapsed since the detection timing of the rising edge.

[0077] When the sampling result is Low, it indicates that the inspection result is "OK", and in other cases, it indicates that the inspection result is "NG". For example, as shown in FIG. 8(b), when the discharge timing signal 401a with a pulse width of width T1 is received, the sampling result becomes Low, and the CPU 601 interprets that the inspection result of the sheet is "OK". On the other hand, as shown in FIG. 8(c), when the discharge timing signal 401b with a pulse width of width T2 is received, the sampling result becomes High, and the CPU 601 interprets that the inspection result of the sheet is "NG".

[0078] In this embodiment, the width T1 is set smaller than the width T2 (T1 < T2), but the width T1 may be set larger than the width T2 (T1 > T2). And when T1 > T2, when the sampling result is High, the inspection result is interpreted as "OK". Therefore, "when the sampling result is Low and T1 < T2, or when the sampling result is High and T1 > T2" is the condition for interpreting the inspection result as "OK".

[0079] Also, in this embodiment, the logical value of the discharge timing signal 401 is sampled when the time of (T1 + T2) / 2 has elapsed from the detection timing of the rising edge, but it is not limited to this. For example, the logical value of the discharge timing signal 401 may be sampled when the time α has elapsed from the detection timing of the rising edge. The time α is a time larger than the time corresponding to the width T1 and smaller than the time corresponding to the width T2.

[0080] [Output Processing of Discharge Timing Signal Based on Inspection Result] FIG. 9 is a flowchart showing the operation related to the transmission and reception of signals of the image forming apparatus 10 when performing inspection processing. In particular, the flowchart of FIG. 9 is obtained by adding steps S32 to S36 to the flowchart of FIG. 6, and the processing for outputting a discharge timing signal according to the inspection result is added.

[0081] 9, the CPU 201 in the printer control unit 200 turns on the operation instruction signal 403 via the communication I / F 204 (step S31). Then, the CPU 201 determines whether the trailing end of the sheet has passed through the sheet reading sensor 121 (step S32). If it is determined that the trailing end of the sheet has passed through the sheet reading sensor 121 (step S32: Yes), the CPU 201 obtains the inspection result from the inspection processing unit 210 (step S33).

[0082] 1, the conveying path 124 is longer than the maximum sheet length that can be fed by the image forming apparatus 10. Therefore, the image forming apparatus 10 can complete the reading by the sheet reading sensor 121 and the inspection process before the leading edge of the sheet reaches the discharge outlet of the image forming apparatus 10.

[0083] Next, the CPU 201 judges whether the acquired inspection result is "OK" or not (step S34). If the inspection result is "OK" (step S34: Yes), the CPU 201 sets the pulse width of the discharge timing signal to width T1 (step S35). If the inspection result is "NG" (step S34: No), the CPU 201 sets the pulse width of the discharge timing signal to width T2 (step S36).

[0084] Then, the CPU 201 waits for the sheet corresponding to the inspection result acquired in step S33 to arrive at the discharge outlet (not shown) of the image forming apparatus 10 (step S37). If it is determined that the leading edge of the sheet has arrived at the discharge outlet of the image forming apparatus 10 (step S37: Yes), the CPU 201 outputs a discharge timing signal 401 from the communication I / F 204 (step S38). At this time, the pulse width of the discharge timing signal 401 becomes the width set in step S35 or step S36. That is, in step S38, if the inspection result of the sheet is "OK", a discharge timing signal 401a (see FIG. 8(b)) is output, and if the inspection result of the sheet is "NG", a discharge timing signal 401b (see FIG. 8(c)) is output.

[0085] Next, CPU 201 judges whether the sheet is the last sheet of the set (step S39). If it is judged to be the last sheet of the set (step S39: Yes), CPU 201 outputs a last sheet signal 402 from communication I / F 204 (step S40). On the other hand, if it is judged not to be the last sheet of the set (step S39: No), CPU 201 does not instruct communication I / F 204 to output last sheet signal 402.

[0086] Next, the CPU 201 determines whether the sheet is the last sheet of the job (step S41). If it is determined that the sheet is the last sheet of the job (step S41: Yes), the CPU 201 waits for reception of a last sheet processing end signal 405 by the communication I / F 204 (step S42). If the last sheet processing end signal 405 is received (step S42: Yes), the CPU 201 turns off the operation instruction signal 403 (step S43) and ends the flow. On the other hand, if it is determined in step S41 that the sheet is not the last sheet of the job (step S41: No), the CPU 201 returns to the process of step S32.

[0087] [Process of sorting deliverables by section based on discharge timing signal] 10 and 11 are flowcharts for explaining the process of sorting the deliverables by set in accordance with the discharge timing signal by the sheet processing apparatus 1000 according to the present embodiment. In particular, the flowcharts of Fig. 10 and 11 are obtained by adding steps S53, S55 to S58, and S64 to S67 to the flowchart of Fig. 7, and perform the sorting process according to the inspection result.

[0088] First, as shown in FIG. 10, the CPU 601 of the sheet processing apparatus 1000 judges whether the operation instruction signal 403 is ON or not through the communication I / F 604 (step S51). If it is judged that the operation instruction signal 403 is ON (step S51: Yes), the CPU 601 performs an initialization process (step S52). Then, the CPU 601 sets a "good product flag" (step S53). The "good product flag" is a variable indicating whether the deliverable is a good product as a copy, and is used for sorting by copy. The substance of the "good product flag" is stored, for example, in the RAM 602 in the post-processing control unit 600. By setting the "good product flag" in step S52, the sheet processing apparatus 1000 can treat a copy of sheets to be received as a good product in advance, and at the time of receiving a defective sheet, treat a copy that may contain the defective sheet as a defective product.

[0089] Next, the CPU 601 waits to detect the rising edge of the discharge timing signal 401 (step S54). If it is detected that the discharge timing signal 401 has risen (step S54: Yes), the CPU 601 waits for a period of (T1+T2) / 2 (step S55). Then, the CPU 601 samples the logical value of the discharge timing signal 401 (step S56).

[0090] Next, the CPU 601 judges whether the logical value of the sampled discharge timing signal 401 is Low or not (step S57). If the sampling result is Low (step S57: Yes), the process proceeds to step S59. On the other hand, if the sampling result is not Low (step S57: No), the CPU 601 clears the "non-defective part flag" (step S58) and proceeds to step S59.

[0091] Next, the CPU 601 performs a sheet storage process (step S59). Then, the CPU 601 determines whether the sheet storage process is completed (step S60), similar to step S15 in Fig. 7. The CPU 601 determines that the sheet storage process is completed based on the elapse of a time period corresponding to the distance from the detection position of the storage unit entrance sensor 1015 to the positioning member 1004 after the storage unit entrance sensor 1015 is turned ON.

[0092] If it is determined that the sheet storage process is completed (step S60: Yes), the CPU 601 outputs a sheet reception response signal 404 to the image forming apparatus 10 (step S61). Next, the CPU 601 determines whether or not the last sheet signal 402 has been received (step S62). If it is determined that the last sheet signal 402 has not been received (step S62: No), the CPU 601 returns to the process of step S54. On the other hand, if it is determined that the last sheet signal 402 has been received (step S62: Yes), the CPU 601 performs post-processing for each set, as shown in FIG. 11 (step S63).

[0093] Next, the CPU 601 determines whether or not the "non-defective product flag" is set (step S64). If the "non-defective product flag" is set (step S64: Yes), the CPU 601 instructs a discharge load, such as a motor or roller, at the end of the input / output port IC 603 to discharge the product onto the first discharge tray 1012 (step S65). That is, a first process is performed on the sheet. On the other hand, if the "non-defective product flag" is not set (step S64: No), the CPU 601 instructs a discharge load, such as a motor or roller, to discharge the product onto the second discharge tray 1014 (step S66). That is, a second process different from the first process is performed on the sheet.

[0094] Next, CPU 601 sets the "non-defective product flag" (step S67) and outputs final paper processing end signal 405 to image forming apparatus 10 (step S68). Next, CPU 601 determines whether or not the rising edge of discharge timing signal 401 has been detected (step S69). If it is determined that the rising edge of discharge timing signal 401 has been detected (step S69: Yes), CPU 601 returns to the process of step S55. On the other hand, if it is determined that the rising edge of discharge timing signal 401 has not been detected (step S69: No), CPU 601 determines whether or not operation instruction signal 403 is OFF (step S70).

[0095] If it is determined that the operation instruction signal 403 is ON (step S70: No), the CPU 601 returns to the process of step S69. If it is determined that the operation instruction signal 403 is OFF (step S70: Yes), the CPU 601 performs a stop process (step S71) and ends the flow. The stop process here is to stop driving the pair of inlet rollers 1001, etc.

[0096] As described above, in this embodiment, if the inspection result is OK, the communication I / F 204 of the image forming apparatus 10 outputs a discharge timing signal 401a having a pulse width of T1 to the sheet processing apparatus 1000. If the inspection result is NG, the communication I / F 204 of the image forming apparatus 10 outputs a discharge timing signal 401b having a pulse width of T2 (T2>T1) to the sheet processing apparatus 1000. That is, the communication I / F 204 outputs a discharge timing signal having a different waveform to the sheet processing apparatus 1000 via the discharge timing signal line 2501 depending on the inspection result.

[0097] When the sheet processing apparatus 1000 receives the discharge timing signal 401a, it discharges the sheet, which is the product, to the first discharge tray 1012, and when the sheet processing apparatus 1000 receives the discharge timing signal 401b, it discharges the sheet to the second discharge tray 1014. In this way, by transmitting a discharge timing signal having a waveform according to the inspection result, it is possible to include two pieces of information, "that the sheet has been discharged from the image forming apparatus 10" and "the inspection result is OK / NG", in the discharge timing signal.

[0098] Therefore, there is no need to prepare a dedicated signal line for transmitting "inspection result OK / NG" in addition to the discharge timing signal line 2501, and there is no need to provide ports for connecting the signal line in the image forming apparatus 10 and the sheet processing apparatus 1000. Thus, it is possible to obtain the image forming apparatus 10 and the image forming system 1 that improve the degree of freedom of device combination in an inline configuration while suppressing an increase in the number of signals of the parallel I / F.

[0099] 11, post-processing is always performed regardless of the inspection result, but the present invention is not limited to this. For example, post-processing may be omitted for a part for which the "part-pass flag" is cleared in step S58, i.e., a part that includes a sheet that has failed inspection.

[0100] In addition, in the present embodiment, the sheets that pass the inspection are discharged to the first discharge tray 1012, and the sheets that fail the inspection are discharged to the second discharge tray 1014, but this is not limiting. In other words, as long as the processing for the sheets that pass the inspection and the sheets that fail the inspection are different, the processing to be performed may be set arbitrarily.

[0101] <Second embodiment> Next, a second embodiment of the present invention will be described, which is configured by changing only the waveform of the discharge timing signal of the first embodiment and the method by which the sheet processing apparatus 1000 interprets the inspection result from the discharge timing signal. Therefore, the same configuration as the first embodiment will be omitted from the illustrations or will be described by using the same reference numerals in the drawings.

[0102] [Superimposition of inspection results on discharge timing signal] 12(a) to 12(c) are timing charts for explaining a means for superimposing the inspection result for each sheet on the discharge timing signal 421 according to this embodiment, and a method for the sheet processing apparatus 1000 to interpret the inspection result from the discharge timing signal 421. More specifically, FIG. 12(a) is a timing chart showing the waveform of the discharge timing signal 421 output from the image forming apparatus 10. FIGS. 12(b) and 12(c) are timing charts for explaining the interpretation of the discharge timing signal 421 received by the sheet processing apparatus 1000. There are two types of discharge timing signals 421, discharge timing signals 421a and 421b, which will be described later, for the discharge timing signal 421.

[0103] 12(a) to 12(c), a period T3 indicates a period during which the sheet processing apparatus 1000 counts the number of pulses, and the start point of the period T3 is the rising edge of the first pulse corresponding to each sheet. A cycle T4 indicates a cycle of sheet discharge, and the relationship of T4>T3 is satisfied.

[0104] The CPU 201 (see FIG. 2) inquires of the inspection processing unit 210 about the sheet inspection result before outputting the discharge timing signal 421. Then, if the inspection result is OK, that is, if the sheet is of good quality and there is no image defect, the CPU 201 outputs one discharge timing signal 421a having a first number of pulses to the sheet processing apparatus 1000 from the communication I / F 204 as shown in FIG. 12(a). That is, the discharge timing signal 421a has a first waveform.

[0105] On the other hand, when the inspection result is "NG", that is, when the product is defective and there is an image defect, the CPU 201 outputs two discharge timing signals 421b having a second number of pulses to the sheet processing apparatus 1000 from the communication I / F 204. The discharge timing signal 421b has a second waveform different from the first waveform because the number of pulses of the discharge timing signal 421a is different from that of the discharge timing signal 421a. For example, the signal output from the image forming apparatus 10 has a discharge timing signal 421a corresponding to the first sheet, a discharge timing signal 421b corresponding to the second sheet, and a discharge timing signal 421a corresponding to the third sheet. This signal is a signal when printing three sheets per copy, and indicates that the inspection results of the first and third sheets are "OK" and the inspection result of the second sheet is "NG".

[0106] 12(b) and (c), the interpretation of the inspection result in the sheet processing apparatus 1000 will be described. When the discharge timing signal 421 is output from the image forming apparatus 10, the CPU 601 of the sheet processing apparatus 1000 first detects the rising edge of the discharge timing signal 421 via the communication I / F 604. Then, the CPU 601 counts the number of rising pulses from the detection timing of the rising edge until the elapse of the period T3 (including the start point of the period T3).

[0107] A single rising edge indicates that the inspection result is "OK", and a double rising edge indicates that the inspection result is "NG". For example, as shown in FIG. 12(b), when a discharge timing signal 421a with one pulse is received, the CPU 601 interprets the inspection result of the sheet as "OK". On the other hand, as shown in FIG. 12(c), when a discharge timing signal 421b with two pulses is received, the CPU 601 interprets the inspection result of the sheet as "NG". With this configuration, it is possible to achieve the same effect as the first embodiment.

[0108] In this embodiment, the number of pulses when the inspection result is "OK" is set to one, and the number of pulses when the inspection result is "NG" is set to two, but the number of pulses in period T3 may be set arbitrarily as long as the inspection results can be distinguished. Also, in this embodiment, the number of rising edges of the pulses is counted, but the number of pulses may be recognized by counting the number of falling edges of the pulses.

[0109] <Third embodiment> Next, a third embodiment of the present invention will be described, which is configured by changing only the waveform of the discharge timing signal of the first embodiment and the method by which the sheet processing apparatus 1000 interprets the inspection result from the discharge timing signal. Therefore, the same configuration as the first embodiment will be omitted from the illustrations or will be described by using the same reference numerals in the drawings.

[0110] [Control Block] Fig. 13 is a block diagram for explaining the image forming system according to the present embodiment. Fig. 13 is a diagram in which a DAC 204a is added to the printer control unit 200 and a comparator 604a is added to the post-processing control unit 600 in the block diagram of Fig. 2, so only the differences are described here.

[0111] The DAC 204a of the printer control unit 200 is a device that can output a discharge timing signal 431 of any voltage to a discharge timing signal line 2501. The CPU 201 can output the discharge timing signal 431 of any voltage via the DAC 204a.

[0112] Furthermore, the comparator 604b of the post-processing control unit 600 can determine whether the voltage of the discharge timing signal line 2501 is greater than or equal to a reference voltage Vref (not shown). The CPU 201 can determine via the comparator 604b whether the voltage of the discharge timing signal 431 is greater than or equal to a reference voltage Vref (not shown).

[0113] [Superimposition of inspection results on discharge timing signal] Figs. 14(a) to (c) are timing charts for explaining means for superimposing inspection results per sheet on the discharge timing signal 431 according to the present embodiment and a method by which the sheet processing apparatus 1000 interprets inspection results from the discharge timing signal 431. More specifically, Fig. 14(a) is a timing chart showing the waveform of the discharge timing signal 431 output from the image forming apparatus 10. Figs. 14(b) and (c) are timing charts for explaining the interpretation of the discharge timing signal 431 received by the sheet processing apparatus 1000. There are two types of discharge timing signals 431, namely the discharge timing signals 431a and 431b, which will be described later.

[0114] The maximum voltage Vmax in Figs. 14(b) and (c) indicates the maximum voltage that can be received by the sheet processing apparatus 1000, and the reference voltage Vref is a threshold value for the CPU 601 to determine whether the inspection result is "OK" or "NG" via the comparator 604b.

[0115] When outputting the discharge timing signal 431, the CPU 201 (see Fig. 13) inquires of the inspection processing unit 210 about the inspection result of the sheet. When the inspection result is OK, that is, the product is a good product and there is no image defect, the CPU 201 outputs, as shown in Fig. 14(a), the discharge timing signal 431a of the voltage V1 as the first voltage from the communication I / F 204 to the sheet processing apparatus 1000. That is, the discharge timing signal 431a has the first waveform.

[0116] On the other hand, when the inspection result is "NG", that is, the product is a defective product and there is an image defect, the CPU 201 outputs, from the communication I / F 204 to the sheet processing apparatus 1000, the discharge timing signal 431b of the voltage V2 as the second voltage. Here, the magnitude relationship of the respective voltages is as follows. The voltage V1 is smaller than the reference voltage Vref, the voltage V2 is equal to or higher than the reference voltage Vref and smaller than the maximum voltage Vmax (V1 < Vref ≤ V2 < Vmax). Since the discharge timing signal 431b has a different voltage from the discharge timing signal 431a, it has a second waveform different from the first waveform.

[0117] For example, the signal output from the image forming apparatus 10 includes a discharge timing signal 431a corresponding to the first sheet, a discharge timing signal 431b corresponding to the second sheet, and a discharge timing signal 431a corresponding to the third sheet. This signal is a signal when performing printing of three sheets per unit, and indicates that the inspection results of the first and third sheets are "OK" and the inspection result of the second sheet is "NG".

[0118] Subsequently, with reference to FIGS. 14(b) and 14(c), the interpretation of the inspection results in the sheet processing apparatus 1000 will be described. When the discharge timing signal 431 is output from the image forming apparatus 10, first, the CPU 601 of the sheet processing apparatus 1000 detects the rising edge of the discharge timing signal 431 by the communication I / F 604. Then, the CPU 601 checks whether the voltage of the discharge timing signal 431 is less than the reference voltage Vref or greater than or equal to the reference voltage Vref by the comparator 604b.

[0119] When the voltage of the discharge timing signal 431 is less than the reference voltage Vref, it indicates that the inspection result is "OK", and when the voltage of the discharge timing signal 431 is greater than or equal to the reference voltage Vref, it indicates that the inspection result is "NG". For example, as shown in FIG. 14(b), when the discharge timing signal 431a with the voltage V1 (<Vref) is received, the CPU 601 interprets that the inspection result of the sheet is "OK". On the other hand, as shown in FIG. 14(c), when the discharge timing signal 431b with the voltage V2 (≧Vref) is received, the CPU 601 interprets that the inspection result of the sheet is "NG". With such a configuration, the same effects as those of the first embodiment can be achieved.

[0120] In this embodiment, it is determined whether the inspection result is "OK" or "NG" with the reference voltage Vref as a threshold value, but the voltages V1, V2, and the reference voltage Vref may be set in any manner as long as the inspection results can be distinguished. For example, the magnitude relationship of the voltages may be set as V2 < Vref ≦ V1.

[0121] <Fourth Embodiment> Next, a fourth embodiment of the present invention will be described, which is configured by superimposing the inspection result on the final paper signal. Therefore, the same configuration as the first embodiment will be described by omitting illustrations or by assigning the same reference numerals in the drawings.

[0122] [Superimposing inspection results onto final paper signal] 15(a) to 16(b) are timing charts for explaining a means for superimposing the inspection result for each set on the last sheet signal 402 in this embodiment. As shown in Figs. 15(a) and 15(b), signals sent from the image forming apparatus 10 to the sheet processing apparatus 1000 include a discharge timing signal 401 and a last sheet signal 402. The discharge timing signal 401 is output corresponding to each sheet discharged from the image forming apparatus 10 to the sheet processing apparatus 1000, and the last sheet signal 402 is output only corresponding to the last sheet that constitutes a set. There are two types of last sheet signals 402a and 402b, which will be described later.

[0123] In this embodiment, when outputting the last sheet signal 402, the CPU 201 inquires of the inspection processing unit 210 about the inspection result of the entire set (sheet stack). Then, if the inspection result of the entire set is OK, that is, if the sheets are good and there are no image defects, the CPU 201 outputs a last sheet signal 402a having a pulse width of width T1 to the sheet processing apparatus 1000 from the communication I / F 204 as shown in FIG. 15(a). That is, the last sheet signal 402a has a first waveform. Note that the inspection result of the entire set being OK means that it is determined that none of the sheets constituting the sheet stack have image defects in the inspection process.

[0124] When the inspection result of the entire part is "NG", that is, when it is a defective product with an image defect, as shown in FIG. 15(b), the CPU 201 outputs a final sheet signal 402b with a pulse width of width T2 from the communication I / F 204 to the sheet processing apparatus 1000. Since the width T2 is larger than the width T1, the final sheet signal 402b has a second waveform different from the first waveform. Note that the inspection result of the entire part being NG means that an image defect has been determined in any of the sheets constituting the sheet bundle during the inspection process.

[0125] Subsequently, with reference to FIGS. 16(a) and 16(b), the interpretation of the inspection result in the sheet processing apparatus 1000 will be described. When the final sheet signal 402 is output from the image forming apparatus 10, first, the CPU 601 of the sheet processing apparatus 1000 detects the rising edge of the final sheet signal 402 by the communication I / F 604. Then, the CPU 601 samples the logical value of the final sheet signal 402 when a time of (T1 + T2) / 2 has elapsed from the detection timing of the rising edge.

[0126] When the sampling result is Low, it indicates that the inspection result is "OK", and in other cases, it indicates that the inspection result is "NG". For example, as shown in FIG. 16(a), when the final sheet signal 402a with a pulse width of width T1 is received, the sampling result becomes Low, and the CPU 601 interprets that the inspection result of the corresponding part (sheet bundle) is "OK". On the other hand, as shown in FIG. 16(b), when the final sheet signal 402b with a pulse width of width T2 is received, the sampling result becomes High, and the CPU 601 interprets that the inspection result of the corresponding part (sheet bundle) is "NG".

[0127] In the present embodiment, the width T1 is set smaller than the width T2 (T1 < T2), but the width T1 may be set larger than the width T2 (T1 > T2). And when T1 > T2, when the sampling result is High, the inspection result is interpreted as "OK". Therefore, "when the sampling result is Low and T1 < T2, or when the sampling result is High and T1 > T2" is the condition for interpreting the inspection result as "OK".

[0128] [Final paper signal output processing based on inspection results] 17 and 18 are flowcharts showing operations related to signal transmission and reception of the image forming apparatus 10 when performing inspection processing. First, as shown in FIG. 17, the CPU 201 in the printer control unit 200 turns on the operation instruction signal 403 via the communication I / F 204 (step S81). Then, the CPU 201 determines whether the trailing end of the sheet has passed through the sheet reading sensor 121 (step S82). If it is determined that the trailing end of the sheet has passed through the sheet reading sensor 121 (step S82: Yes), the CPU 201 obtains the inspection result from the inspection processing unit 210 (step S83).

[0129] Next, the CPU 201 determines whether the acquired inspection result is "NG" (step S84). If the inspection result is "NG" (step S84: Yes), the CPU 201 sets the part inspection NG flag ON and proceeds to step S86. If the inspection result is "OK" (step S84: No), the CPU 201 proceeds to step S86 without setting the part inspection NG flag ON.

[0130] Then, CPU 201 waits for the sheet corresponding to the inspection result acquired in step S83 to reach the discharge outlet (not shown) of image forming apparatus 10 (step S87). If it is determined that the leading edge of the sheet has reached the discharge outlet of image forming apparatus 10 (step S87: Yes), CPU 201 outputs discharge timing signal 401 from communication I / F 204 (step S88).

[0131] Next, the CPU 201 determines whether the sheet is the last sheet of the set (sheet stack) (step S88). If it is determined that the sheet is the last sheet of the set (step S88: Yes), the CPU 201 determines whether the part inspection NG flag is ON (step S89). If the part inspection NG flag is ON (step S89: Yes), the CPU 201 sets the pulse width of the last sheet signal to T2 (step S90). On the other hand, if the part inspection NG flag is OFF (step S89: No), the CPU 201 sets the pulse width of the last sheet signal to T1 (step S91).

[0132] Then, the CPU 201 clears the part inspection NG flag (step S92) and outputs a last sheet signal with the pulse width set in steps S90 and S91. That is, the CPU 201 outputs a last sheet signal 402b with a pulse width of T2 or a last sheet signal 402a with a pulse width of T1 from the communication I / F 204 (step S93). Note that, if it is determined in step S88 that the sheet is not the last sheet of the part (step S88: No), the process proceeds to step S94.

[0133] Next, CPU 201 determines whether the sheet is the last sheet of the job (step S94). If it is determined that the sheet is the last sheet of the job (step S94: Yes), CPU 201 waits for reception of a last sheet processing end signal 405 by communication I / F 204 (step S95). If the last sheet processing end signal 405 is received (step S95: Yes), CPU 201 turns off operation instruction signal 403 (step S96) and ends the flow. On the other hand, if it is determined in step S94 that the sheet is not the last sheet of the job (step S94: No), CPU 201 returns to the process of step S82.

[0134] [Process of sorting the deliverables by copy based on the final paper signal] 19 and 20 are flowcharts for explaining the process in which the sheet processing apparatus 1000 according to the present embodiment sorts the deliverables by set in accordance with the last-sheet signal.

[0135] 19, the CPU 601 of the sheet processing apparatus 1000 determines whether the operation instruction signal 403 is ON or not through the communication I / F 604 (step S101). If it is determined that the operation instruction signal 403 is ON (step S101: Yes), the CPU 601 performs an initialization process (step S102).

[0136] Next, the CPU 601 waits for receipt of the discharge timing signal 401 (step S103). If the discharge timing signal 401 is received (step S103: Yes), the CPU 601 judges whether or not the last paper signal 402 is received (step S104). If it is judged that the last paper signal 402 is not received (step S104: No), the process proceeds to step S110. If it is judged that the last paper signal is received (step S104: Yes), the CPU 601 judges whether or not a period of (T1+T2) / 2 has elapsed (step S105). If a period of (T1+T2) / 2 has elapsed (step S105: Yes), the CPU 601 samples the logical value of the last paper signal 402 (step S106).

[0137] Next, the CPU 601 judges whether the sampling result is High or not (step S107). If the sampling result is High (step S107: Yes), the CPU 601 sets the discharge destination of the copy (sheet stack) to the second discharge tray 1014 (step S108). On the other hand, if the sampling result is Low (step S107: No), the CPU 601 sets the discharge destination of the copy (sheet stack) to the first discharge tray 1012 (step S109).

[0138] Next, the CPU 601 performs a sheet storage process (step S110). Then, the CPU 601 judges whether the sheet storage process is completed or not (step S111). The CPU 601 judges that the sheet storage process is completed based on the fact that the time equivalent to the distance from the detection position of the storage unit entrance sensor 1015 to the positioning member 1004 has elapsed since the storage unit entrance sensor 1015 was turned ON.

[0139] If it is determined that the sheet storage process is completed (step S111: Yes), the CPU 601 outputs a sheet reception response signal 404 to the image forming apparatus 10 (step S112). Next, the CPU 601 determines whether the sheet is the last sheet of the set (sheet stack) (step S113). If it is determined that the sheet is not the last sheet of the set (sheet stack) (step S113: No), the process returns to step S103.

[0140] If it is determined that the sheet is the last sheet of a set (sheet stack) (step S113: Yes), the CPU 601 performs post-processing for each set (step S114) as shown in Fig. 20. Next, the CPU 601 determines whether the discharge destination of the set is the first discharge tray 1012 (step S115).

[0141] If it is determined that the discharge destination of the relevant part is the first discharge tray 1012 (step S115: Yes), the CPU 601 instructs a discharge load such as a motor or roller to discharge the relevant part to the first discharge tray 1012 (step S116). That is, a first process is performed on the sheet bundle. If it is determined that the discharge destination of the relevant part is not the first discharge tray 1012 (step S115: No), the CPU 601 instructs a discharge load such as a motor or roller to discharge the relevant part to the second discharge tray 1014 (step S117). That is, a second process different from the first process is performed on the sheet bundle.

[0142] Next, the CPU 601 outputs a final paper processing end signal 405 to the image forming apparatus 10 (step S118). The CPU 601 then judges whether or not the discharge timing signal 401 has been received (step S119). If it is judged that the discharge timing signal 401 has been received (step S119: Yes), the CPU 601 returns to the process of step S104. On the other hand, if it is judged that the discharge timing signal 401 has not been received (step S119: No), the CPU 601 judges whether or not the operation instruction signal 403 is OFF (step S120).

[0143] If it is determined that the operation instruction signal 403 is ON (step S120: No), the CPU 601 returns to the process of step S119. On the other hand, if it is determined that the operation instruction signal 403 is OFF (step S120: Yes), the CPU 601 performs a stop process (step S121) and ends the flow. Here, the stop process is to stop driving the pair of inlet rollers 1001, etc.

[0144] 20, the flow is such that post-processing is always performed regardless of the inspection result, but the present invention is not limited to this. For example, the flow may be configured such that post-processing is not performed on the part whose discharge destination is set to the second discharge tray 1014 in step S108, that is, the part containing the sheet that has failed inspection. With this configuration, it is possible to achieve the same effect as the first embodiment.

[0145] In the present embodiment, a sheet bundle that passes inspection is discharged to the first discharge tray 1012, and a sheet bundle that fails inspection is discharged to the second discharge tray 1014, but this is not limiting. In other words, as long as the processing for sheets that pass inspection and sheet bundles that fail inspection are different, the processing to be performed may be set arbitrarily.

[0146] In the present embodiment, the inspection result is superimposed on the last sheet signal 402 by changing the pulse width of the last sheet signal 402 to widths T1 and T2, but the present invention is not limited to this. For example, the inspection result may be superimposed on the last sheet signal 402 by changing the number of pulses of the last sheet signal 402 as in the second embodiment. Also, the inspection result may be superimposed on the last sheet signal 402 by changing the voltage of the last sheet signal 402 as in the third embodiment.

[0147] <Fifth embodiment> Next, a fifth embodiment of the present invention will be described. The fifth embodiment is configured by superimposing the inspection result on the discharge timing signal and the last paper signal. Therefore, the same configuration as the fourth embodiment will be omitted from the illustration or will be described by assigning the same reference numerals in the drawings. Note that in this embodiment, an example will be described in which the inspection result is superimposed on the discharge timing signal 401 and the last paper signal 402 by setting the pulse width of the pulse signal to widths T1 and T2.

[0148] [Process to sort the deliverables by set based on the discharge timing signal and the last paper signal] 21 and 22 are flowcharts for explaining the process in which the sheet processing apparatus 1000 according to this embodiment sorts the deliverables by set in accordance with a discharge timing signal and a last-sheet signal.

[0149] 21, the CPU 601 of the sheet processing apparatus 1000 determines whether the operation instruction signal 403 is ON or not through the communication I / F 604 (step S131). If it is determined that the operation instruction signal 403 is ON (step S131: Yes), the CPU 601 performs an initialization process (step S132).

[0150] Next, the CPU 601 turns off the sheet inspection NG flag (step S133) and waits for receipt of the discharge timing signal 401 (step S134). If the discharge timing signal 401 is received (step S134: Yes), the CPU 601 determines whether the period of (T1+T2) / 2 has elapsed (step S135). If the period of (T1+T2) / 2 has elapsed (step S135: Yes), the CPU 601 samples the logical value of the discharge timing signal 401 (step S136).

[0151] Next, the CPU 601 determines whether the sampling result is High or not (step S137). If the sampling result is High (step S137: Yes), the sheet inspection NG flag is turned ON (step S138) and the process proceeds to step S139. If the sampling result is Low (step S137: No), the sheet inspection NG flag is not turned ON and the process proceeds to step S139.

[0152] Next, the CPU 601 determines whether or not the last paper signal 402 has been received (step S139). If it is determined that the last paper signal 402 has not been received (step S139: No), the process proceeds to step S146. If it is determined that the last paper signal has been received (step S139: Yes), the CPU 601 determines whether or not a period of (T1+T2) / 2 has elapsed (step S140). If a period of (T1+T2) / 2 has elapsed (step S140: Yes), the CPU 601 samples the logical value of the last paper signal 402 (step S141).

[0153] Next, the CPU 601 judges whether the sampling result is High or not (step S142). If the sampling result is High (step S142: Yes), the CPU 601 sets the discharge destination of the copy (sheet stack) to the second discharge tray 1014 (step S143) and proceeds to step S146. On the other hand, if the sampling result is Low (step S142: No), the CPU 601 judges whether the sheet inspection NG flag is OFF or not (step S144). If the sheet inspection NG flag is OFF (step S144: Yes), the CPU 601 sets the discharge destination of the copy (sheet stack) to the first discharge tray 1012 (step S145) and proceeds to step S146. If the sheet inspection NG flag is ON (step S144: No), proceeds to step S143.

[0154] Next, the CPU 601 performs a sheet storage process (step S146). Then, the CPU 601 judges whether or not the sheet storage process is completed (step S147). If it is judged that the sheet storage process is completed (step S147: Yes), the CPU 601 outputs a sheet reception response signal 404 to the image forming apparatus 10 (step S148). Next, the CPU 601 judges whether or not the sheet is the last sheet of the set (sheet stack) (step S149). If it is judged that the sheet is not the last sheet of the set (sheet stack) (step S149: No), the process returns to step S134.

[0155] If it is determined that the sheet is the last sheet of a set (sheet stack) (step S149: Yes), the CPU 601 performs post-processing for each set (step S150) as shown in Fig. 22. Next, the CPU 601 determines whether the discharge destination of the set is the first discharge tray 1012 (step S151).

[0156] If it is determined that the discharge destination of the part is the first discharge tray 1012 (step S151: Yes), the CPU 601 instructs a discharge load such as a motor or roller to discharge the part to the first discharge tray 1012 (step S152). If it is determined that the discharge destination of the part is not the first discharge tray 1012 (step S151: No), the CPU 601 instructs a discharge load such as a motor or roller to discharge the part to the second discharge tray 1014 (step S153).

[0157] Next, the CPU 601 outputs a final paper processing end signal 405 to the image forming apparatus 10 (step S154). The CPU 601 then judges whether or not the discharge timing signal 401 has been received (step S155). If it is judged that the discharge timing signal 401 has been received (step S155: Yes), the CPU 601 returns to the process of step S135. On the other hand, if it is judged that the discharge timing signal 401 has not been received (step S155: No), the CPU 601 judges whether or not the operation instruction signal 403 is OFF (step S156).

[0158] If it is determined that the operation instruction signal 403 is ON (step S156: No), the CPU 601 returns to the process of step S155. If it is determined that the operation instruction signal 403 is OFF (step S156: Yes), the CPU 601 performs a stop process (step S157) and ends the flow. The stop process here is to stop driving the pair of inlet rollers 1001, etc.

[0159] 22, post-processing is always performed regardless of the inspection result, but the present invention is not limited to this. For example, the configuration may be such that post-processing is not performed on the part whose discharge destination is set to the second discharge tray 1014 in step S143, that is, the part that includes the sheet that failed inspection.

[0160] The above-described configuration can achieve the same effects as those of the first embodiment. In addition, by superimposing the inspection result on both the discharge timing signal 401 and the last sheet signal 402, post-processing in the sheet processing apparatus 1000 can be performed with high accuracy according to the inspection result.

[0161] Sixth embodiment Next, a sixth embodiment of the present invention will be described. In addition to the configuration of the first embodiment, the sixth embodiment is configured to superimpose the post-processing result on the sheet reception response signal 404 output by the sheet processing apparatus 1000. Therefore, the same configuration as the first embodiment will not be illustrated or will be described by assigning the same reference numerals in the drawings. Note that, like the first embodiment, the image forming apparatus 10 of this embodiment is configured to superimpose the inspection result on the discharge timing signal 401 by setting the pulse width of the pulse signal to widths T1 and T2.

[0162] FIG. 23 is a table showing the correspondence between the processing content performed by the sheet processing apparatus 1000 and the sheet reception response signal 404. As the post-processing end signal, the sheet reception response signal 404 has two types, namely, the sheet reception response signals 404a and 404b described later. The sheet processing apparatus 1000 performs one of the following two types of processing on each sheet sent from the image forming apparatus 10.

[0163] The first type of processing is a sheet storage process of storing the sheet in the sheet storage unit 1003. In that case, when the sheet storage process is completed, the sheet processing apparatus 1000 outputs, as shown in FIG. 23, a sheet reception response signal 404a having a pulse width of width T11 as the first pulse width. That is, the sheet reception response signal 404a has a first waveform and is output when the processing of the sheet determined to have no image defect in the inspection process is completed.

[0164] The second type of processing is an escape discharge process of discharging the sheet to the purge tray 1053. In that case, when the process of discharging the sheet to the purge tray 1053 is completed, the sheet processing apparatus 1000 outputs a sheet reception response signal 404b having a pulse width of width T12 as the second pulse width. That is, the sheet reception response signal 404b has a second waveform different from the first waveform and is output when the processing of the sheet determined to have an image defect in the inspection process is completed.

[0165] Note that the relationship between the pulse widths of the sheet reception response signals 404a and 404b is T11 < T12, and the method of distinguishing between the sheet reception response signals 404a and 404b is the same as the method by which the CPU 601 distinguishes the discharge timing signals 401a and 401b. That is, these can be distinguished by checking the logic of the sheet reception response signals 404a and 404b at the timing when a period of (T11 + T12) / 2 has elapsed from the rising edge of the sheet reception response signals 404a and 404b.

[0166] 24 is a timing chart showing waveforms of a discharge timing signal 401 output from the image forming apparatus 10 and a sheet reception response signal 404 output from the sheet processing apparatus 1000. For example, as shown in Fig. 24, the signals output from the image forming apparatus 10 include a discharge timing signal 401a corresponding to the first sheet, a discharge timing signal 401b corresponding to the second sheet, and a discharge timing signal 401a corresponding to the third sheet. This signal indicates that the inspection results of the first and third sheets are "OK" and the inspection result of the second sheet is "NG".

[0167] Signals output from the sheet processing apparatus 1000 include a sheet receipt response signal 404a corresponding to the first sheet, a sheet receipt response signal 404b corresponding to the second sheet, and a sheet receipt response signal 404b corresponding to the third sheet. These signals indicate that the sheet storage process has been performed on the first and third sheets, and that the second sheet has been escape-discharged to the purge tray 1053. That is, a sheet whose inspection result is "OK" is discharged as a deliverable to the first discharge tray 1012 or the second discharge tray 1014, but a sheet whose inspection result is "NG" is discharged to the purge tray 1053 since it cannot be used as a deliverable.

[0168] [Processing to notify post-processing results] 25 and 26 are flowcharts for explaining a process of the sheet processing apparatus 1000 notifying the image forming apparatus 10 of post-processing results for each sheet according to the present embodiment.

[0169] First, as shown in FIG. 25, the CPU 601 of the sheet processing apparatus 1000 judges whether the operation instruction signal 403 is ON or not through the communication I / F 604 as a transmission unit (step S161). If it is judged that the operation instruction signal 403 is ON (step S161: Yes), the CPU 601 performs an initialization process (step S162). Then, the CPU 601 sets a "good product flag" (step S163). The "good product flag" is a variable indicating whether the deliverable is a good product as a copy, and is used for sorting by copy. The substance of the "good product flag" is stored, for example, in the RAM 602 in the post-processing control unit 600. By setting the "good product flag" in step S162, the sheet processing apparatus 1000 can treat a copy of sheets to be received as a good product in advance, and at the time of receiving a defective sheet, treat a copy that may contain the defective sheet as a defective product.

[0170] Next, the CPU 601 waits to detect the rising edge of the discharge timing signal 401 (step S164). If it is detected that the discharge timing signal 401 has risen (step S164: Yes), the CPU 601 waits for a period of (T1+T2) / 2 (step S165). Then, the CPU 601 samples the logical value of the discharge timing signal 401 (step S166).

[0171] Next, the CPU 601 judges whether the logical value of the sampled discharge timing signal 401 is Low or not (step S167). If the sampled result is Low (step S167: Yes), the CPU 601 sets the pulse width of the sheet reception response signal 404 to width T11 (step S168). Then, the CPU 601 executes a sheet storage process for storing the sheet in the sheet storage unit 1003 (step S169), and judges whether the sheet storage process is completed (step S170). If the sheet storage process is completed (step S170: Yes), the process proceeds to step S175.

[0172] On the other hand, if the sampling result is High (step S167: No), the CPU 601 sets the pulse width of the sheet reception response signal 404 to width T12 (step S171). Then, the CPU 601 executes an escape discharge process for discharging the sheet to the purge tray 1053 (step S172), and determines whether the escape discharge process is completed (step S173). If the escape discharge process is completed (step S173: Yes), the CPU 601 clears the "non-defective part flag" (step S174), and proceeds to step S175.

[0173] Next, the CPU 601 outputs the sheet reception response signal 404 to the image forming apparatus 10 (step S175). The pulse width of the sheet reception response signal 404 at this time is the pulse width set in steps S168 and S171. Next, the CPU 601 judges whether or not the last sheet signal 402 has been received (step S176). If it is judged that the last sheet signal 402 has not been received (step S176: No), the CPU 601 returns to the process of step S164. On the other hand, if it is judged that the last sheet signal 402 has been received (step S176: Yes), the CPU 601 performs post-processing for each set, as shown in FIG. 26 (step S177).

[0174] Next, CPU 601 determines whether or not the "good part flag" is set (step S178). If the "good part flag" is set (step S178: Yes), CPU 601 instructs a discharge load such as a motor or roller to discharge the product onto first discharge tray 1012 (step S179). If the "good part flag" is not set (step S178: No), CPU 601 instructs a discharge load such as a motor or roller to discharge the product onto second discharge tray 1014 (step S180). The set (sheet stack) discharged onto second discharge tray 1014 does not include the sheets discharged onto purge tray 1053 in step S172.

[0175] Next, CPU 601 sets the "non-defective product flag" (step S181) and outputs final paper processing end signal 405 to image forming apparatus 10 (step S182). Next, CPU 601 determines whether or not the rising edge of discharge timing signal 401 has been detected (step S183). If it is determined that the rising edge of discharge timing signal 401 has been detected (step S183: Yes), CPU 601 returns to the process of step S165. On the other hand, if it is determined that the rising edge of discharge timing signal 401 has not been detected (step S183: No), CPU 601 determines whether or not operation instruction signal 403 is OFF (step S184).

[0176] If it is determined that the operation instruction signal 403 is ON (step S184: No), the CPU 601 returns to the process of step S183. If it is determined that the operation instruction signal 403 is OFF (step S184: Yes), the CPU 601 performs a stop process (step S185) and ends the flow. The stop process here is to stop driving the pair of inlet rollers 1001, etc.

[0177] [Escape discharge processing notification] Next, a process for notifying the operation unit 20 that the sheet processing apparatus 1000 has executed the escape discharge process will be described with reference to Fig. 27. As shown in Fig. 27, the CPU 201 of the image forming apparatus 10 waits for detection of a rising edge of the sheet reception response signal 404 (step S191).

[0178] If it is detected that the sheet reception response signal 404 has risen (step S191: Yes), the CPU 201 waits for a period of (T11+T12) / 2 (step S192). Then, the CPU 201 samples the logical value of the sheet reception response signal 404 (step S193).

[0179] Next, the CPU 201 judges whether the logical value of the sampled sheet reception response signal 404 is Low or not (step S194). If the sampling result is Low (step S194: Yes), the CPU 201 judges that the post-processing type performed by the sheet processing apparatus 1000 was the sheet storage process (step S195) and proceeds to step S198. On the other hand, if the sampling result is High (step S194: No), the CPU 201 judges that the post-processing type performed by the sheet processing apparatus 1000 was the escape discharge process (step S196). Then, the CPU 201 determines that there are escape-discharged sheets on the purge tray 1053 and sheets discharged on the second discharge tray 1014, and causes the operation unit 20 as a notification unit to display the fact that the sheets have been sorted and discharged to these (step S197).

[0180] Next, CPU 201 determines whether the job is completed (step S198). The job is determined to be completed when communication I / F 204 receives final paper processing completion signal 405, for example. If it is determined that the job is not completed (step S198: No), the process returns to step S191, and if it is determined that the job is completed (step S198: Yes), the flow ends.

[0181] Fig. 28 is a diagram showing an example of a screen displayed on the operation unit 20 in step S197 in Fig. 27. As shown in Fig. 28, when the escape discharge process is executed, sheets are discharged to the purge tray 1053 and the second discharge tray 1014, and the presence of sheets in these trays is notified to the user by a display on the operation unit 20. Then, in response to this display, the user determines whether the discharged sheets can be reused or whether reprinting is required.

[0182] As described above, by notifying the image forming apparatus 10 of the processing performed by the sheet processing apparatus 1000 based on the inspection result, it is possible to provide an appropriate notification to the user without adding a new signal line. Therefore, it is possible to obtain the sheet processing apparatus 1000 and the image forming system 1 that improve the degree of freedom of device combination and usability in an inline configuration while suppressing an increase in the number of signals of the parallel I / F.

[0183] In the present embodiment, the user is notified by displaying on the operation unit 20 that there are sheets that have escaped to the purge tray 1053 and sheets that have been discharged to the second discharge tray 1014, but this is not limiting. That is, the user may be notified not only by a screen display on the operation unit 20 but also by an alarm sound, a lamp light, or the like.

[0184] In the present embodiment, the pulse width of the sheet reception response signal 404 is changed to widths T11 and T12 to superimpose the post-processing result on the sheet reception response signal 404, but this is not limiting. For example, the number of pulses of the sheet reception response signal 404 may be changed as in the second embodiment to superimpose the post-processing result on the sheet reception response signal 404. Also, the voltage of the sheet reception response signal 404 may be changed as in the third embodiment to superimpose the inspection result on the sheet reception response signal 404.

[0185] <Seventh embodiment> Next, a seventh embodiment of the present invention will be described. The seventh embodiment differs from the sixth embodiment in the interpretation of the sheet reception response signal 404 by the image forming apparatus 10 and the action taken in response to the sheet reception response signal 404. For this reason, the same configuration as the sixth embodiment will be omitted from the illustration or will be described with the same reference numerals in the drawings. Note that, like the sixth embodiment, the image forming apparatus 10 of this embodiment is configured to superimpose the inspection result on the discharge timing signal 401 by setting the pulse width of the pulse signal to widths T1 and T2. Also, the sheet processing apparatus 1000 is configured to superimpose the inspection result on the sheet reception response signal 404 by setting the pulse width of the pulse signal to widths T11 and T12.

[0186] The following configuration is expected in an image forming system in which the image forming apparatus 10 cannot instruct the sheet processing apparatus 1000 on the type of post-processing. That is, when the post-processing of the sheet processing apparatus 1000 changes depending on the image inspection result transmitted by the image forming apparatus 10, it is expected that the inspection result and the post-processing result are linked.

[0187] Therefore, in this embodiment, the image forming apparatus 10 holds in advance in the ROM 205 the type of post-processing expected from the sheet processing apparatus 1000 according to the inspection result. Then, by comparing the post-processing type information superimposed on the sheet reception response signal 404 from the sheet processing apparatus 1000 with the expected result in the ROM 205, it is possible to confirm whether the expected post-processing has been performed. The details of this will be described below.

[0188] 29 is a table showing combinations of inspection results and expected sorting processes (post-processing types) stored in the ROM 205. Pattern 1 specifies that when the inspection result is OK, the operation expected of the sheet processing apparatus 1000 is sheet storage processing. On the other hand, pattern 2 specifies that when the inspection result is NG, the operation expected of the sheet processing apparatus 1000 is escape discharge processing.

[0189] [Output processing of discharge timing signal based on inspection results] 30 and 31 are flowcharts showing operations related to signal transmission and reception of the image forming apparatus 10 when performing the inspection process. First, as shown in FIG. 30, the CPU 201 in the printer control unit 200 turns on the operation instruction signal 403 by the communication I / F 204 (step S201). Then, the CPU 201 judges whether the sheet trailing end has passed the sheet reading sensor 121 (step S202). If it is judged that the sheet trailing end has passed the sheet reading sensor 121 (step S202: Yes), the CPU 201 acquires the inspection result from the inspection processing unit 210 (step S203). After that, the CPU 201 saves the acquired inspection result at the end of the inspection result queue that is stored in the RAM 202 and holds the inspection results in order (step S204).

[0190] Next, the CPU 201 judges whether the acquired inspection result is "OK" or not (step S205). If the inspection result is "OK" (step S205: Yes), the CPU 201 sets the pulse width of the discharge timing signal to width T1 (step S206). If the inspection result is "NG" (step S205: No), the CPU 201 sets the pulse width of the discharge timing signal to width T2 (step S207).

[0191] Then, as shown in Fig. 31, the CPU 201 waits for the sheet corresponding to the inspection result acquired in step S203 to arrive at the discharge outlet (not shown) of the image forming apparatus 10 (step S208). If it is determined that the leading edge of the sheet has arrived at the discharge outlet of the image forming apparatus 10 (step S208: Yes), the CPU 201 outputs a discharge timing signal 401 from the communication I / F 204 (step S209). At this time, the pulse width of the discharge timing signal 401 becomes the width set in step S206 or step S207. That is, in step S209, if the inspection result of the sheet is "OK", a discharge timing signal 401a (see Fig. 8(b)) is output, and if the inspection result of the sheet is "NG", a discharge timing signal 401b (see Fig. 8(c)) is output.

[0192] Next, CPU 201 determines whether the sheet is the last sheet of the set (step S210). If it is determined that the sheet is the last sheet of the set (step S210: Yes), CPU 201 outputs a last sheet signal 402 from communication I / F 204 (step S211). On the other hand, if it is determined that the sheet is not the last sheet of the set (step S210: No), CPU 201 does not instruct communication I / F 204 to output last sheet signal 402.

[0193] Next, CPU 201 determines whether the sheet is the last sheet of the job (step S212). If it is determined that the sheet is the last sheet of the job (step S212: Yes), CPU 201 waits for reception of a last sheet processing end signal 405 by communication I / F 204 (step S213). If the last sheet processing end signal 405 is received (step S213: Yes), CPU 201 turns off operation instruction signal 403 (step S214) and ends the flow. On the other hand, if it is determined in step S212 that the sheet is not the last sheet of the job (step S212: No), CPU 201 returns to the process of step S202. [Comparison of inspection results and expected sorting process] Next, a process of comparing the inspection result with the expected sorting process by the image forming apparatus 10 will be described with reference to Fig. 32 and Fig. 33. As shown in Fig. 32, the CPU 201 of the image forming apparatus 10 waits for detection of a rising edge of the sheet reception response signal 404 (step S221).

[0194] If it is detected that the sheet reception response signal 404 has risen (step S221: Yes), the CPU 201 waits for a period of (T11+T12) / 2 (step S222). Then, the CPU 201 samples the logical value of the sheet reception response signal 404 (step S223).

[0195] Next, the CPU 201 judges whether the logical value of the sampled sheet reception response signal 404 is Low or not (step S224). If the sampling result is Low (step S224: Yes), the CPU 201 judges that the type of post-processing performed by the sheet processing apparatus 1000 was sheet storage processing (step S225) and proceeds to step S227. On the other hand, if the sampling result is High (step S224: No), the CPU 201 judges that the type of post-processing performed by the sheet processing apparatus 1000 was escape discharge processing (step S226).

[0196] Next, the CPU 201 acquires the top inspection result from the contents of the inspection result queue present in the RAM 202 (step S227). Then, the CPU 201 checks the inspection result acquired in step S227 and the post-processing type determined in step S225 or step S226 against the table described in FIG.

[0197] Specifically, as shown in Fig. 33, the CPU 201 judges whether the inspection result acquired in step S227 is OK (step S228). If the inspection result is OK (step S228: Yes), the CPU 201 judges whether the post-processing type judged in step S225 or step S226 was sheet storage processing (step S229). If the post-processing type is sheet storage processing (step S229: Yes), it matches pattern 1 in Fig. 29, so it is found that post-processing was performed without any problem in the sheet processing apparatus 1000, and the process proceeds to step S233.

[0198] If the post-processing type is not the sheet storage process (step S229: No), it does not match either pattern 1 or pattern 2 shown in Fig. 29, and therefore it is found that the expected post-processing has not been performed in the sheet processing apparatus 1000. Then, the CPU 201 displays a confirmation message, which will be described later, on the operation unit 20 (step S230), and proceeds to step S233.

[0199] If the inspection result is NG in step S228 (step S228: No), the CPU 201 judges whether the post-processing type judged in step S225 or step S226 was sheet storage processing (step S231). If the post-processing type is sheet storage processing (step S231: Yes), it does not match either pattern 1 or pattern 2 shown in Fig. 29, and therefore it is found that the expected post-processing was not performed in the sheet processing apparatus 1000. Then, the CPU 201 displays a confirmation message described later on the operation unit 20 (step S232), and proceeds to step S233.

[0200] If the post-processing type is not the sheet storage process (step S231: No), it matches pattern 2 shown in FIG. 29, so it is found that the post-processing has been performed without any problem in the sheet processing apparatus 1000, and the process proceeds to step S233.

[0201] Next, CPU 201 deletes the top inspection result from the inspection result queue stored in RAM 202 (step S233). Furthermore, CPU 201 determines whether the job is completed or not (step S234). The job is determined to be completed, for example, when communication I / F 204 receives final paper processing completion signal 405. If it is determined that the job is not completed (step S234: No), the flow returns to step S221, and if it is determined that the job is completed (step S234: Yes), the flow ends.

[0202] Fig. 34 is a diagram showing a confirmation message displayed on the operation unit 20 in steps S230 and S232 in Fig. 33. The confirmation message is displayed on the operation unit 20 when post-processing expected for the detection result of the detection process has not been performed by the sheet processing apparatus 1000. The confirmation message prompts the user to review the settings of the sheet processing apparatus 1000.

[0203] In this embodiment, the combination of the inspection result and the expected sorting process (post-processing type) is stored in advance in the ROM 205, but is not limited to this. For example, if it is necessary to change this combination depending on the user or the type of the sheet processing apparatus 1000 used, the combination may be configured to be changeable from the operation unit 20, for example.

[0204] As described above, by comparing the post-processing result superimposed on the sheet reception response signal 404 with the inspection result, the image forming apparatus 10 can grasp whether or not appropriate post-processing has been performed in the sheet processing apparatus 1000. Specifically, when the sheet reception response signal 404b is output in response to a sheet determined to have no image defects, or when the sheet reception response signal 404a is output in response to a sheet determined to have an image defect, a confirmation message is displayed. This allows the user to be appropriately notified without adding a new signal line. Therefore, it is possible to obtain the sheet processing apparatus 1000 and the image forming system 1 that improve the degree of freedom of device combination and usability in an inline configuration while suppressing an increase in the number of signals of the parallel I / F.

[0205] In the present embodiment, the user is notified by displaying the confirmation message shown in Fig. 34 on the operation unit 20, but the present invention is not limited to this. That is, the user may be notified not only by a screen display on the operation unit 20 but also by an alarm sound, a lamp light, or the like.

[0206] <Other embodiments> In any of the above-described embodiments, the sheets and copies whose inspection results are OK are configured to be discharged to the first discharge tray 1012. Also, the sheets and copies whose inspection results are NG are configured to be discharged to the second discharge tray 1014 or the purge tray 1053, but this is not limiting. For example, the sheets and copies whose inspection results are OK may be configured to be discharged to the second discharge tray 1014 or the purge tray 1053.

[0207] In addition, in any of the above-described embodiments, three trays, namely, the first discharge tray 1012, the second discharge tray 1014, and the purge tray 1053, are provided, but the number of trays is not limited to this. For example, the number of trays may be two, or four or more.

[0208] In the present embodiment, the inspection mechanism including the sheet reading sensor 121 is provided in the image forming apparatus 10, but is not limited thereto. For example, another device having an inspection mechanism may be interposed between the image forming apparatus 10 and the sheet processing apparatus 1000. The inspection mechanism may also be provided in the sheet processing apparatus 1000. The judgment of whether a product is good or defective in the inspection process may be performed outside the image forming system 1.

[0209] In addition, in any of the above-described embodiments, the image forming apparatus 10 is an electrophotographic image forming apparatus, but the present invention is not limited to this. For example, an inkjet image forming apparatus that forms an image on a sheet by ejecting ink liquid from a nozzle may be used.

[0210] Moreover, the first to seventh embodiments described above may be combined in any manner.

[0211] The present invention can also be realized by a process in which a program for implementing one or more of the 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 invention can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions. [Explanation of symbols]

[0212] 1: Image forming system / 10: Image reading device (image forming device) / 20: Notification unit (operation unit) / 121: Reading unit (sheet reading sensor) / 200: Printer control unit / 204: Transmission unit (communication I / F) / 210: Acquisition unit (inspection processing unit) / 401: Discharge timing signal / 402: Last paper signal / 404: Post-processing end signal (sheet reception response signal) / 604: Transmission unit (communication I / F) / 1000: Sheet processing device / 1 012: first discharge tray / 1014: second discharge tray / 1200: post-processing section (discharge section) / 2501: signal line (discharge timing signal line) / 2502: signal line (last paper signal line) / 2505: signal line (last paper processing end signal line) / T1: first pulse width (width) / T2: second pulse width (width) / T11: first pulse width (width) / T12: second pulse width (width) / V1: first voltage (voltage) / V2: second voltage (voltage)

Claims

1. A sheet processing apparatus that performs post-processing on a sheet discharged from an image forming apparatus, the sheet processing apparatus including an image forming unit that forms an image on a sheet, and an inspection unit that reads the image on the sheet formed by the image forming unit and inspects for the presence or absence of an image defect, a post-processing section for processing a sheet discharged from the image forming apparatus; a receiving unit that receives, via a signal line, a discharge timing signal indicating a timing at which a sheet is to be discharged from the image forming apparatus; a control unit that controls the post-processing unit based on the discharge timing signal received by the receiving unit, The control unit is When the receiving unit receives the discharge timing signal having a first waveform that is output when a sheet determined to have no image defects by the inspection unit is discharged, a first process is performed on the sheet by the post-processing unit; When the receiving unit receives the discharge timing signal having a second waveform different from the first waveform output when the sheet determined to have an image defect by the inspection unit is discharged, the post-processing unit executes a second process different from the first process on the sheet. A sheet processing apparatus comprising:

2. the ejection timing signal having the first waveform has a first pulse width; the ejection timing signal having the second waveform has a second pulse width different from the first pulse width; 2. The sheet processing apparatus according to claim 1, wherein the sheet processing apparatus is a sheet processing apparatus.

3. the ejection timing signal having the first waveform has a first number of pulses; the ejection timing signal having the second waveform has a second number of pulses different from the first number.

2. The sheet processing apparatus according to claim 1, wherein the sheet processing apparatus is a sheet processing apparatus.

4. the ejection timing signal having the first waveform has a first voltage; the ejection timing signal having the second waveform has a second voltage different from the first voltage; 2. The sheet processing apparatus according to claim 1, wherein the sheet processing apparatus is a sheet processing apparatus.

5. Having a first discharge tray and a second discharge tray, the first process is a process of discharging a sheet onto the first discharge tray, the second process is a process of discharging the sheet onto the second discharge tray; 5. The sheet processing apparatus according to claim 1, wherein the sheet processing apparatus is a sheet processing apparatus.

6. A sheet processing apparatus that is connected to an image forming apparatus including an image forming unit that forms an image on a sheet and an inspection unit that reads the image on the sheet formed by the image forming unit and inspects for image defects, and that performs post-processing on a sheet discharged from the image forming apparatus, a post-processing section for processing a sheet discharged from the image forming apparatus; a receiving unit that receives, via a signal line, a last sheet signal indicating that the sheet discharged from the image forming apparatus is the last sheet constituting a sheet stack; a control unit that controls the post-processing unit based on the last sheet signal received by the receiving unit, The control unit is when the receiving unit receives the last sheet signal having a first waveform that is output when the inspection unit determines that there is no image defect in any of the sheets that make up the sheet stack, a first process is performed on the sheets by the post-processing unit; when the receiving unit receives the last sheet signal having a second waveform different from the first waveform outputted when the inspection unit determines that any of the sheets constituting the sheet stack has an image defect, the post-processing unit executes a second process different from the first process on the sheet. A sheet processing apparatus comprising:

7. the final paper signal having the first waveform has a first pulse width; the final paper signal having the second waveform has a second pulse width different from the first pulse width.

7. The sheet processing apparatus according to claim 6,

8. the final paper signal having the first waveform has a first number of pulses; the final paper signal having the second waveform has a second number of pulses different from the first number.

7. The sheet processing apparatus according to claim 6,

9. the final paper signal having the first waveform has a first voltage; the final paper signal having the second waveform has a second voltage different from the first voltage.

7. The sheet processing apparatus according to claim 6,

10. A device having a first discharge tray and a second discharge tray, the first process is a process of discharging a sheet stack onto the first discharge tray, the second process is a process of discharging the sheet stack onto the second discharge tray; 7. The sheet processing apparatus according to claim 6,

11. A transmission unit that transmits a post-processing end signal indicating that the post-processing unit has completed processing of the sheet to the image forming apparatus via a signal line, the transmission unit outputs the post-processing end signal having a third waveform to the signal line when the first processing is completed, and outputs the post-processing end signal having a fourth waveform different from the third waveform to the signal line when the second processing is completed.

7. The sheet processing apparatus according to claim 1, wherein the sheet processing apparatus is a sheet processing apparatus.

12. the post-processing end signal having the third waveform has a first pulse width; the post-processing end signal having the fourth waveform has a second pulse width different from the first pulse width; The sheet processing apparatus according to claim 11 .

13. the post-processing done signal having the third waveform has a first number of pulses; the post-processing completion signal having the fourth waveform has a second number of pulses different from the first number. The sheet processing apparatus according to claim 11 .

14. the post-processing end signal having the third waveform has a first voltage; the post-processing end signal having the fourth waveform has a second voltage different from the first voltage; The sheet processing apparatus according to claim 11 .

15. A sheet processing apparatus according to any one of claims 1 to 14, The image forming apparatus includes:

1. An image forming system comprising:

Images